1/8 scale electric- Part II [Archive] - Page 2

Combatcm

04-28-2005, 09:45 AM

Sunday I hit the track and raced it against a total of 21 other buggy drivers. After the morning practice I noticed that the front of the can was comming off, so I took some heavy blunt objects and pounded it back and CA'd it, before then only the endbell came off. To take the shock away from the jumps, I took some heavy dense foam and put it under the motor and then screwed the diff down. I never had any trouble the rest of the day.

To last the race I used 6 cell packs in paralell. They give good acceleration, but make it go less than 30, which makes the car noticibly slower than the rest. The low RPM made it nose dive after the 2 set of doubles, however after a few laps I had the throttle memorized to land on the opposite side of the second jump almost all the time.

I qualified I think 5th or 6th for the A main, I like taking it easy, so I came out last after the first set of turns. The main lasted without incident and I finished 3rd. In 2 races my buggy was marshalled once. 3rd out of 21 people.

It was funny during practice I stopped for a second and some guy took it off the track, and I drove off while he watched it.

AFTER the races was when I gave it a total beatdown. After losing a steering turnbuckle and breaking a camber turnbuckle I continued to drive it off jumps and smash it into things. It's all good now, though I am using traxxas standard size turbuckle which I hope will last, but they are cheaper and easier to get. They are really small compared to everything else.

Some things you'll notice is the reciever was mounted on the custom front brace, but it glitched horribly, so I had to velcro it directly to the chassis. The receiver pack is zip tied to the battery cup strap. I made new 8 cell packs just so I can have more power on the track. Although 16 cells is going to be a handful off track.

I also included a picture of the multi connector there are 2 connector coming out of the ESC for racing, so I don't have more of a chance of a solder malfunction. With the connector you can run;

1 pack
2 packs series
2 pack paralell
3 packs series

-all by just swapping the connectors and the jumper connector.

http://i3.photobucket.com/albums/y93/combatcm/DSCI0010.jpg
http://i3.photobucket.com/albums/y93/combatcm/DSCI0006.jpg
http://i3.photobucket.com/albums/y93/combatcm/DSCI0008.jpg
http://i3.photobucket.com/albums/y93/combatcm/DSCI0011.jpg
The only picture I got while I was there
http://i3.photobucket.com/albums/y93/combatcm/DSCI0001.jpg

Batfish

04-28-2005, 11:57 AM

Great post and pictures, Combatcm.

Once I finalize a way to hold my batteries in, I'll be running mine at my local track with the nitros as well.
I'll have two 6-cells or two 8-cells wired in parallel for the runtime, but will also have the capability to run 12, 14, or 16 cells in series with the packs I have.
Good idea on the connectors. Have you tried PowerPoles? They're incredibly easy to configure for series, but do require a y-harness for parallel.

I have a few pics and a short video of mine at:
http://www.******.net/member/Batfish

It's the Hyper 7 TQ Sport kit with the following:
BK Warrior 9918
Feigao 8L - 15t pinion (I went with the 8L to get more speed out of less voltage. It's less efficient, but still works.)
Blue Bird high torque MG servo
Hitec HFS-03MM receiver
IB3600 cells in MEC Solderless PowerTubes (the video on ******.net was filmed with one 6-cell unmatched GP3300 stick pack)
Receiver pack (4-cell alkaline right now)

BL_Force

04-28-2005, 01:41 PM

Hi guys. I just got my Hyper 7 last week. I'm in the process of hocking all the nitro stuff on ebay. I have a 9L and a u-force 75 i'm going to put in it. I'll post pics as I progress. Right now i'm tied up with my savage brushless conversion.

Mr. Constructor

04-29-2005, 04:58 AM

Be careful with the Force 75, it is very hard on its limits in a 8th scaler !!
Anyway, someone new who comes to the growing crowd of beeing an 8th scale electric enthusiast !!!

I do really was busy the past few months, but i promise it wasn´t for daydreams !!

anyway the Hyper 7 seems to be a great car and much used in the states as i think, so this one will be up for me too.

(but i do have a LST first !!! ;-) )

BL_Force

04-29-2005, 10:27 AM

Mr. Constructor

04-29-2005, 03:05 PM

def. YES, the amp draw in those Buggys will be higher than the Force 75 might handle, we do have heard of several people having trouble with them in their cars generating too much heat !!!

The esc is best used in the 10th scale sektor, for 8th the very last vew amps of cont power are missing.

If you wanna be on the safe side do get yourself a new Esc specially for the 8th buggy, in this "class" it´ll be always better to have some more power than normally used as there are too many unsuspected tasks that might ruin your esc AND your wallet ;-))

Good Luck !!

TimisTim

04-29-2005, 03:32 PM

Is Jamie going to have any of the newer software MGM 120amp controllers soon? I'm getting my UF 75 back next week from germany and may just sell it.

Mr. Constructor

04-30-2005, 03:46 AM

I will have them in stock soon, but what´s up with Jamie ???
(I do know that he did stock some too, maybe he received the new ones ??)

By the way, i was sending several of the olders in, to get them updated, i think they´ll be back soon and then we could figure the real performance out form these esc´s !

starluckrc

04-30-2005, 10:36 AM

I'm waiting on the new batch......plus I have some other things up my sleeve as well ;-).

sugs

04-30-2005, 05:19 PM

Great!....There he goes again....dangling the carrot!....better warm up the plastic!

TimisTim

04-30-2005, 06:15 PM

Well if I can find a buyer for my U-Force then I'll take one of what you have up your sleeve :p

What are the prices you are expecting for the MGM 120amp?

starluckrc

05-01-2005, 01:05 PM

I expect retail to remain at $199, so I'll be below that.

Combatcm

05-03-2005, 02:08 AM

This 2nd race could, but probably won't, be my last. They passed an official rule in our club to outlaw brushless systems in all electric classes, unless its a BL only class. And I've had a few people go up to me, say a friendly statement how its illegal for brushless to run, kind of asking me to not race it, but not flat out saying I can't run it. However its a nitro class, not electric that I am running a brushless system in, this is the reason why it's so sketchy. Mind you, this is club racing, no money, just mini plaques (I have a bunch of 3rd place ones from last year and a first place when my buggy was nitro, as well as a third place one from this year) and as one member announced at the race "we don't race for anything but personal satisfaction." I see nothing more satisfying than making an electric buggy and having success both on and off track with it.

Anyway, I qualified 3rd this race and took 4th at the end. The turnbuckles held up (right off a rustler), motor bell didn't pop out, nothing overheated, nothing stripped, mesh stayed the same, all good. Here are some shots from the main.

http://i3.photobucket.com/albums/y93/combatcm/buggypic3.jpg

http://i3.photobucket.com/albums/y93/combatcm/buggypic2.jpg

http://i3.photobucket.com/albums/y93/combatcm/Buggypic1.jpg

Batfish

05-03-2005, 11:41 AM

It's been my experience that noone cares what you're running until you beat them. In a racing environment, the only time anyone asks about your setup is when your vehicle ends the race ahead of them.

Racing my 1/8th brushless at my local track will only be at "unofficial" because I expect the same reaction. As you put it, I am finding the most personal satisfaction in creating the vehicle and learning to drive/control it. If I happen to win, so much the better.

Combatcm

05-03-2005, 03:06 PM

I agree. If it becomes a bigger problem I'll buy a novak XR HV and use a graupner boat motor.

TimisTim

05-03-2005, 03:16 PM

I love how this is coming from the nitro crowd at the races. All the nitro guys I talk to are very biased and blow off my brushless as slow just becase it is electric. I can't wait for the day when I build a buggy to race against them.

Hobson

05-12-2005, 09:37 AM

My 'Work-In-Progress' E-Rex. (http://gazdesigns.fpic.co.uk/c537010.html)

rstnboy

05-12-2005, 10:35 AM

I love how this is coming from the nitro crowd at the races. All the nitro guys I talk to are very biased and blow off my brushless as slow just becase it is electric.

I got the same reaction when I wanted to race mine at the local track. It was a club race and no one there has a chance to use the results to get sponsorship or even some form of recognized endorsement. My response was, "If it's not a threat then you shouldn't mind me running it then, right?" That kind of shut them up and I got to run it.

Combatcm

05-12-2005, 05:35 PM

That's it right there, I believe that electric 1/8th scale buggies are the ultimate track car. Set up right they can pull faster lap times than any other car on the track, electric, nitro, a 1/8th scale electric buggy will rock everything off the track.

tcolesen

05-14-2005, 12:19 PM

I got my 1/8 electric running! I got it last Saturday. The buggy is a XTM X-Terminator, or in europe, a E-Rex (like Hobson's 3 posts up). The center diff's break holes are off to the side, so I had to accomodate those. The motor plate is mounted in 3 spots: the break mount holes, a piece of aluminum angle on the center diff support, and another piece of aluminum angle connecting the motor plate to the chassis. Battery holders are those from an E-Maxx, and each one is connected to the rock guards by 3 screws, and then to the chassis with 3 screws. The motor is a Feigao 8L. The buggy runs well, except that I am using an 18t pinion, so I get heat and cogging. I will be ordering a 15t soon, so hopefully things will get better. Pics:

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0675.jpg
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0682.jpg
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0690.jpg
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0698.jpg

Mr. Constructor

05-15-2005, 06:46 AM

Looks pretty good, but only one thing might be a better solution, try to make a Motor holder that Protects the Motor from Swinging down, maybe a small L shaped alu piece that was filed to the 36 mm diameter of the motor and then screwed under the back 1/3 of the motor, this will help to prevent a Motor damage due to breaking the front end.(after a hard landing or similar)

anyway it is a good car, we have it here in europe called the REX car, it is a car from GV Racing from Taiwan, pretty good construction, very sturdy, only a few bad parts (not really when you using electric !! ;-)) )

Have fun with it !!

Sherminator

05-15-2005, 07:17 AM

tcolesen: looks like its pretty fast, just look at those tires!!! hehe

glassdoctor

05-18-2005, 12:42 AM

After getting my buggy alive again and juiced up on 12 cells, I think I will be going to a lower kv motor next. The 8L I think will be more than neccessary on my track. :)

I have a 13T pinion and can't go much lower so I think I'll bump up to a 10-11L to get a better blend of power/effeciency/runtime. It should run longer and cooler and still have plenty of speed.

I'll see about getting a video with the current setup. It's a very basic affordable setup for 1/8 buggies.

MGM120 + Feigao 8L = $270
12 cells 3300 $70

tcolesen

05-18-2005, 12:58 AM

13t pinion? I guess that mine must have been going really slow because of it being so overgeared. I did order a 13t pinion from Starluck RC that should be here in around a week. I would like to be able to run a 9/10L, but this stuff isn't easy for 16 year olds to afford :)

Mr. Constructor - It would definately be a good idea for me to make a motor brace type of thing since the motor plate did get bent a little bit from some impacts. Where on the motor would I attach it though?

Mr. Constructor

05-18-2005, 03:53 AM

best thing to avoid motor damages:

bore 2 other holes in the motor holder, exactly beneath the motors outer diameter, one left one right (or more generally: 2 on opposite directions)
and then use a long screw (should be longer than motor can and 2x plates and little for nuts.
then make a second smaller plate wich has the same bore design than in the motorholder and screw these plate behind the motor with the long screws going to the motorholder, so the endbell will be secured too, it will crash in a very hard hit, but this will be very hard to reach !!
someone posted a pic of such a thing here in the forum, maybe he reads this and could show us this pic again !!

good luck !!

Reinhard

05-19-2005, 05:46 PM

hier gemacht an einem Revo-E

Reinhard

05-19-2005, 05:49 PM

habs nochmal vergrössert...

da sieht man schön - so wie von Mr. Constructor beschrieben - wies gemacht wurde...

Mr. Constructor

05-20-2005, 03:51 AM

thank reinhard, it was exactly the one i was looking after !!!

hopefully this will now clear up any ??? ;-))

this "conversion" will protect the motor by maximum, the chance of breaking a bell is reduced to min.

good luck

glassdoctor

05-23-2005, 09:01 PM

I finally am getting to play with my buggy... got a question about the overheating issues I am having.

I don't know why things are running so hot with my setup. Any of you guys think I should be having trouble?

Kyosho 1/8 buggy
MGM120
C50 12L
11-12 cell GP3300
13/44 pinion/center gear

It runs like heII but it's hot as heII too

I didn't expect problems because it's not much different than what I used to run in my emaxx... and the controller is better than the Hacker Sport 66A, and the 12L motor SHOULD run cooler and easier than the C50 12s Maxx motor right????

tcolesen

05-23-2005, 09:10 PM

I posted a reply in the other thread. But, to your E-Maxx - the gear ratio of the buggy is different than that of the E-Maxx. The E-Maxx has the internal transmission ratio, the spur/pinion ratio, and the diff ratio. The buggy only has the pinion/spur and diff ratios, and so I think your gearing might be too much. But, the 12L should pull more current than the C50Maxx, just because it is a larger rotor.

glassdoctor

05-23-2005, 11:54 PM

Yes... the gearing etc is different. But they are setup for pretty similar performance, and the emaxx of course has big tires and more weight to move.

The motors I haven't given much thought to lately and haven't actually checked the specs to try to compare how many amps they might pull. An "L" motor does of course have higher watt capacity... but it's much lower kv than the 12s and has more torque. Maybe I'm not thinking straight, but I figured the 12L wouldn't have to break a sweat compared to a higher kv and lower torque 12s, so the amps would not be much worse.

That's just a gut feeling and not based on any logical science. :)

I guess the motor was cooler than the C5012s was in my emaxx. @ 150 vs. 180 but the controller must not like the longer rotor.

I would try the 12s but I don't have any 1/8 mod1 pinions.

All I can say is "BRING ON THE MAMBA!!" ha ha ha

Rotary Rocket

05-24-2005, 01:45 AM

Glassdoctor,

I have the same problem with my buggy conversion. I have the Pletty Max, and Hacker Comp controller running on 4S4P LiPo. I also tried Hacker C50, and Feigao 8L with the same results. I was waiting for the latest version of the MGM controller to handle the heat issue. My Hacker gets so hot that it shuts down.

It sounds like it is more of a gearing problem than just my Hacker ESC. If this is true then the Mamba will have the same issue. :(

Mr. Constructor

05-24-2005, 04:27 AM

It mostly IS the gearing, if there are 1-2 teeths lower pinions used (wich does not affect performance that well) it might be solved and running well, on the other hand a hacker sport or comp. is not the best choice for these high amp draw cars, a 100A or higher esc is always better and will stay lot cooler.

but as i posted in the other thread: check also all connectors (even the ones you use to connect the batterys to each other) and do use a smaller pinion or if this might cause trouble (in most cases it will) then use a bigger main spur (an 48 / 13 setup runs perfect on 120A MGM and a 8L with 12 cells.

Good Luck.

glassdoctor

05-24-2005, 08:26 AM

So you have run the MGM120/8L on 12 cells at 48/13 and it didn't overheat? Hmmm...

Seems that I should not have any problem with a 12L at 46/13. I will go back to a 46 center gear... then try the 10T pinion. After that I give up...

vad

05-24-2005, 11:33 AM

Is there any relationship between the number of turns a motor has and temperature? By reading the last few post, I assume that when comparing a 8L to the 12L, the 12L should run cooler. Is this a correct?

Mr. Constructor

05-24-2005, 11:59 AM

Normally yes, but to some unknown reasons it makes a difference in wich car it is put, some cars seem to be more "forgiving" than others.
the last reason why the C50 12 L will get hotter is that: the rotor is smaller and not segmented, but normally these differences should not be that much that it overheats in one way, and runs cool the other way !!

there could be small defect inside the motor: one of the wires is broken or causes little voltage to run through others (not yet a short cut, but a smaller version of it, we call it "Kriechstrom" in germany.

Maybe you shall look up your screws is there one screwed in too long ???

(look at the wires inside (the winding itself) maybe there is a small punkture on it, then you might overheat due to that, i´ve had that in the past on one motor, it made me go crazy, but finally i found the failure (and threwed the motor away . . . :-(( )

Hobson

05-26-2005, 09:21 AM

Would 48dp be strong enough for an 8th electric? I'm having trouble finding a UK source for MOD-1 pinions, and my thought is to get a 48dp spur and modify it to fit the centre diff on my E-Rex.

tcolesen

05-26-2005, 09:27 AM

I don't think that 48p would be near strong enough. I strip those spurs in my 1/10 Traxxas Rustler with a Feigao "s" motor! I know that this isn't in the UK, but these companies do sell to the UK (or at least StarluckRC does):
http://www.starluckrc.com/catalog/index.php?cPath=23_26
http://www.rc-monster.com/products.php?cat=20&pg=2 (scroll down)

Hobson

05-26-2005, 11:21 AM

Thanks for those links.

The thing is, I'd need a pair of Mod-1 pinions in 1/8" to fit a Feigao 6s (I've got 2 on the way for the car), the RC-Monster say they aren't for metal spur gears. Would it still be OK to use them?

Mr. Constructor

05-26-2005, 12:54 PM

It depends greatly on the metal to metal thing, normally these pinions will not hold that long as the main geras are acting like a saw blade (because they´re too small in width) so another solution should be better: using Nylon, Delrin or any Plastic Gear and then go with wide Steel pinions (mine are 9mm wide on both sides i´ve never had a issue with this combination)

Good Luck !!

Hobson

05-27-2005, 08:07 AM

Thanks for the info (and the PM too).

I've had a thought, would 32dp pinions and spurs (as supplied in the EMaxx) be up to the job of an 8th buggy? My calucations would mean the car will be around 4kg ready to go, with one motor (or two), and a battery pack (or two).

My problem is, if I use Mod-1 pinions, I'd need a plastic spur gear, and I don't know who makes one with the mounting holes (for the centre diff) 2.5mm apart. The the only manufacturer I know that definitley does, is RW, but they are lightweight race spurs.

tcolesen

05-27-2005, 08:54 AM

In case you didn't know, the spur gears for the Monster GT are Mod1. I have a special adapter for my buggy that eliminates the center diff with just a rod that has the spur gear adapter on it. I drill out 2 mounting holes on the Monster GT spurs, and they work fine for me. Maybe you could modify one to work?

EDIT:
BTW, I think that the cars we are working with are the same ones, just with different names (X-Terminator and E-Rex).

Mr. Constructor

05-27-2005, 04:44 PM

the 32 dp modul will not hold that long in those high weighted cars, try the modifying solution tcolesen suggested, it might be the best solution anyway, but i might be able to give you a special mod 1 main gear, maybe even in the fully modified version you might need, it depends on what has to be modified.

email me, i´ll try my best to get it done !!

vad

05-27-2005, 08:24 PM

Any info on this brushless controller, will it work for 1/8 scale buggy applications.

tcolesen

05-27-2005, 08:45 PM

It should definately work for 1/8 buggies. The small size will definately be a plus.

tecman_pants

05-31-2005, 12:34 AM

it looks like you made a pic of that on your computer. 3D

tcolesen

06-01-2005, 06:35 PM

Well, I got my new motor plate/transmission support made. Pics:

I made it using a scroll saw, drill press, and file.
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0726.jpg
The spur gear is a Monster GT 46t mod1, and it will get a 52t soon. I know it is only rear wheel drive right now, but that will be fixed once I get a new center shaft.
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0724.jpg
The motor is now only about 5-6mm off the floor of the chassis. I will be making a brace out of lexan.
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0729.jpg
Here you can see how everything is set up. The speed control fits nicely, and so does the receiver. The entire left side is reserved for the Lipo batts that I will be making very soon.
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0731.jpg
Here is an overall pic of the car:
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0721.jpg

vad

06-02-2005, 01:00 AM

2wd that should be a hand full at speed.

tcolesen

06-02-2005, 08:15 AM

All it does is drift with the slicks on! No traction. But, it will be 4wd soon.

vad

06-02-2005, 01:14 PM

Is the Plettenberg Maxximum motor good for a first brushless motor or is it better to buy a cheaper Feigao 540 10L motor. Also the Plettenberg Maxximum motor has a fan in it does is pass cool air into the motor or pull the heat away from the motor.

Mr. Constructor

06-04-2005, 03:36 AM

vad

06-04-2005, 06:03 PM

the motor choice does not depend on skills, if a certain motor is needed for a car, then it is the best choice.
as for the pletti: the suction or pulling of air depends on the rev. direction, the fan is stucked onto the motors shaft and the rev. direction directly influences this.

for wich car do you plan this motor??

I decided that it would be better to go with a 10L rather than a really high end motor. Now I will just wait till the mamba maxx is released then decide btwn the 12012 mgm or the mamba. Car will be the hyper 7 kit.

Combatcm

06-22-2005, 05:40 PM

Anyone get any 14T or lower hardened mod 1 pinions? The 15T overheats my electronics and thermals my ESC after about 10 minutes.

Mr. Constructor

06-22-2005, 05:57 PM

Try Jamie from Starluck, he has 14 T pinions, but normal hard steel, maybe this will hold up too, i do not know your setup, so it might be a try ???

Give him a call and greetings from me !!

good luck !!

And as for the hyper 7: a conversion kit in my stayle is planned, but might not come till the end of the season, sorry but i do not have had the time for 4 or 5 Prototypes at a time !!

vad

07-03-2005, 02:27 PM

Need help finding a company or web link for making a 6 cell stick pack out of 3300mah loose cells. Someone on here doing a brushless conversion posted a link, but I cant seem to find it. I think Studysession, but not 100% sure.

studysession

07-03-2005, 03:15 PM

This is where I get mine from:
http://www.modelelectronicscorp.com/

tcolesen

07-03-2005, 03:37 PM

Here is a link to one:
http://www.logoheli.com/end2end.htm

vad

07-03-2005, 10:42 PM

Thanks guys, I just ordered the solderless 6 cell tubes.

glassdoctor

07-12-2005, 11:09 PM

Hey... I thought I should post an update on my car cause I ran it today with the GPS unit and modded the controller a bit.

Refresher:
Kyosho 1/8 buggy 777
Hacker C50 12L Frankenstein
MGM 120
11 cell GP3300
And it's still geared 13/44... I never ordered the 10T or swapped out the spur to a 46 yet.

Anyway, I was a little shocked when I hit almost 50MPH in a parking lot today.

I made a few quick passes and was getting around 45, then ran it where it had a couple more seconds to spool up and hit a max of 49.7mph. So if I put the 12th cell back in it would easily break 50 and I think it coulod pull a taller gear and get well over 50... maybe push the 60mph barrier. I don't plan to do that... that's how I smoked my Hacker I think. (:

What all this means?... I think it's safe to say I could probably gear down to the 10 tooth pinion and still has plenty of speed for racing. 49mph is way more than I need and the lower gear will surely cool the motor and esc a lot.

Also.... the MGM120... I added heatsinks to it and it seemed to help quite a bit. I will post more on one of the "MGM" threads....

GPS data from the run...
max speed 49.7
distance 1.81 miles
average speed 15
moving time 7 minutes+
total time about 8.5 minutes

And it did not thermal on this run. But it did thermal after 5+ minutes on the track.

vad

07-12-2005, 11:16 PM

TColsen
The MGT gear you have on your buggy, is that a solid spool or a slipper type diff. How is it working out for you? I have a solid spool from Fioroni that can fit the Hyper 7 and by using Mugen MTX-3 and MRX-3 mod 1 pitch spur gears. Is it difficult to drive with a solid spool with one of these electric conversion as it is with a nitro eng?

tcolesen

07-13-2005, 09:28 AM

The MGT spur I have mounts onto the custom slipper that I use. Since I haven't shown what it looks like, here is a pic:
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0749.jpg
Driving with this certainely isn't like a diff. I have to make sure that I really slow down before I turn, unlike a diff where I can just hold the brake while turning. I am thinking of making some sort of one-way type thing for the front, so it will sort of act like I have a center diff.
Here are some other pics for those that are interested:
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0738.jpg
This one shows my custom aluminum motor mount:
http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_0726.jpg

Gojira

07-14-2005, 09:38 AM

why not run a center slipper like the one in the hpi nitro mt2 then u could run 32 pitch gears ?

Gojira

07-14-2005, 11:18 AM

the mt2 uses the same parts as the savage25

Gojira

07-14-2005, 11:31 AM

im wrong the savage is mod 1

tcolesen

07-14-2005, 12:09 PM

Ya, they are mod1 gears. I have thought of making something like what the HPI MT2 uses, but that uses a 5mm shaft. I have to use a 6mm shaft due to the outputs needing to be 6mm. Since I couldn't find anything to use with a slipper clutch for 6mm, I had to custom make the slipper clutch.

TimisTim

07-14-2005, 01:15 PM

I just finished my conversion on my MT2, but dont have a camera yet! Im dying to get some pics out! I love it so far. I dont want to get off topic, but I hear a grinding/loud clicking noise when I brake very hard. tc your setup looks alot like mine have you any guesses as to what it might be. I thought it might be the center diff because the slipper was to tight so I backed it out another 1/4 turn and it still does it.

Combatcm

07-14-2005, 02:44 PM

That's the ring and pinion gears separating. Add 6 or 7 diff shims for proper engagement, not 2 or 3 per HPI. Maybe aloy gear cases are in order.

I figured I could show what my buggy looks like, Taken a few minutes ago. With a new 5 cell reciever pack and a DX3 radio, ready for glitch free runs. This buggy was a glitch nightmare. It took a way most of the low speed glitching, now all I have to deal with is the slight cogging, not the major cogging that I once thought. My set screws will be happy. It's also got the RC-monster motor plate/heatsink.

http://i3.photobucket.com/albums/y93/combatcm/newbuggy2.jpg

http://i3.photobucket.com/albums/y93/combatcm/newbuggy1.jpg

What you can't see is a severly bent shock shaft, you might noting the wing screwed directly to the wing mounts, the broken front arm, and the broken bumper...and I still run it. I still have the traxxas 4-40 steering links that haven't broken yet.

I ran it a few days ago, by the end of the run (14 minutes parallel 8 cell packs) the esc was 240, the motor was 170 and the batts were 150. I would'nt suggest running anything over 10 cells series in the same setup. performance decreases because of battery resistance. With dual paralell 8 cells it has to pull about 35mph anyway.

tcolesen

07-14-2005, 04:03 PM

What motor are you running?

Combatcm

07-14-2005, 04:06 PM

Feigao 9L

Gojira

07-14-2005, 07:04 PM

anyone know if the ofna 9.5 body will fit a hyper7

Gojira

07-15-2005, 10:10 AM

to everyone what motor or motors do you recomend for a hyper7 on 12-14 nimh cells.I'd like to be just as fast as a nitro or a lil faster,nothing to crazy.I'm planning on running18t pinion to a 52t spur any suggestions

Gojira

07-15-2005, 10:13 AM

tcolesen

07-15-2005, 10:25 AM

I could have used the HPI parts, but there would have been more drilling involved than with the way that I used. I only had to drill out one part for my slipper clutch. Another thing, the MT2 uses a nut to tighten the slipper clutch, which would have been impossible for me to do.

Gojira

07-15-2005, 10:37 AM

tc,did u see my other post,any recomendations

myndseye

08-03-2005, 02:45 PM

maybe these guys can do something for you guys

http://www.rinomechanical.com/spur-gears.htm

tcolesen

08-03-2005, 02:52 PM

tc,did u see my other post,any recomendations
Guess I didn't see it! Here is my response to:

to everyone what motor or motors do you recomend for a hyper7 on 12-14 nimh cells.I'd like to be just as fast as a nitro or a lil faster,nothing to crazy.I'm planning on running18t pinion to a 52t spur any suggestions
Try a Feigao 9L/10L. 18t pinion is going to be too large. Something smaller, around a 14-16t should work. Starluck RC sells mod1 5mm pinions in 12-14t.

Muck

08-07-2005, 08:16 PM

Mr. Constructor

08-08-2005, 03:50 AM

not really, the hyper 7 uses a different middle diff system, but with some work you might be able to adapt a diff from the ultra mbx series, this has a plastik spur wich is very thick and durable.

the reason why many people try to use plastic steel combination are:
1. the lubrication could be left as this is no steel/steel combo (these ones will ever need some lubrication)
2. the thicker the spur or pinion, the better could the forces be transferred
3. plastic is lighter and cheaper than steel
4. plastic main gears are available in more different tooth sizes than steel, this gives more chances to find the right gearing

the hyper 7 isn´t planned yet to be converted by me, but mybe i will do that till next summer, i do have several other conversion kits ready and i am working on several others (Savage, XTM 8th Cars, XB8) sothere is a chance of having it converted too, feel free to email me whenever you like !!

Muck

08-09-2005, 01:31 AM

Thanks for the information Mr. Constructor.

Does anyone know if the MBX center diff will fit using hyper 7 shafts or even the MBX shafts or is it going to require custom drive shafts?

If I could just drill some holes in the chassis and drop a mbx center diff that would not be to hard at all, but getting custom shafts could present some problems though.

Mr. Constructor

08-09-2005, 04:00 AM

you might only need a new chassis plate, if ya then use the original mounting holes and do only vary the lenght in total the shaft lenght isn´t a problem either.
But for coustom made shafts look at my "how to lenghten cvd´s" in this forum, i do give there a very easy solution for getting self made shafts with low costs.

So you could go in 2 ways, choose the one you prefer ;-)

good luck

vad

08-09-2005, 10:34 PM

I've also been thinking about doing a conversion on my hyper 7. One thing I can't figure out though, the spur is steel. From what I've read most people are using a plastic spur and a slipper. That seems ideal to me. I'd love to have the ease of brushless in this buggy.

Is it a good idea to go with the steel spur and no slipper?

Is there a way to get plastic spur and slipper in my buggy?

Muck,

In a hyper 7, the kyosho mp-7.7,777 diff is a direct drop in. If you can get the landmax plastic spurs then replace the steel center gear on the mp-7.5, 777 center diff and you are ready to roll. You might be able to get the plastic 44T gear from RC Mart . com. remove spaces.

You can also try mounting a fioroni solid center spool and mount any plastic gear from the mugen MRX or MTX series cars. Just remove the center section and drill holes to mount the gear to the center spool.

Re-Mix

08-09-2005, 11:37 PM

Ofna makes nylon spur gears for the mbx series. rc-monster.com has them listed for a real steal. Bolt on. A slipper is useless though, most people say it's not worth it in a 1/8th buggy.

Muck

08-10-2005, 02:17 AM

Lots of good possibilities, but it does make me wonder how bad the steel/steel combo would be. Is there a pinion gear that would hold up well?

I think I will go with a minimum of a 4s lipo, but I'm really considering a 5s, 10L Fiago and I still haven't decided on a controller yet.

Mr. Constructor

08-10-2005, 03:56 AM

the problem on steel/steel pairing: lubrication is needed and due to the small thin main gear the gear acts more like a saw for the pinion, so the teeths will be grinded down very fast.
this cries for a very heavy tough steel pinion, wich is not available at the whole industrie (for a fair price off course) so a steel / delrin or plastic combo makes sense and is very cheap too.
(and due to the flexibility of the plastic the main gear could easily hold the power and is lightweight too)

these are the major reasons for plastic main gears another one for the self building people might be that it is easier to machine or work on as hardened steel !!

tcolesen

08-10-2005, 07:26 PM

Ofna makes nylon spur gears for the mbx series. rc-monster.com has them listed for a real steal. Bolt on. A slipper is useless though, most people say it's not worth it in a 1/8th buggy.

Having a slipper in a 1/8 buggy does have its advantages, as long as it is well made. For my XTM X-Terminator, I opted not to use a diff because the one I had was leaking because of the stripped screw holes. My diff is based on a 6mm shaft (for a HPI car) and is cut down to the proper length. I modified the Revo slipper clutch to fit on this shaft. My reason for using a Revo slipper was primarily because I had it from a previous project, and it was unused. So, I got that to fit on. Then I ordered some heavy 25lb. (or something like that) springs, and cut it down to the required length. To hold the spring on, I have a heavy duty steel collar with a 4mm set screw. To tighten the spring, I stick the shaft (with everything on it) into a vice and use one of those pump clamps to put pressure on the spring. Then I tighten the set screw on the collar, and it is done!

This setup caused the rear worn-down diff to last a lot longer. Also, I use a Feigao 8L which is very capable of pulling large amounts of amps (and so generally isn't suggested for use with 1/8 buggies). But this slipper will slip a little on takeoff, making the peak amp draw lower (thus being easier on the motor, controller, and batteries). The only downside is that I don't get the "diff action" which I did like, but I feel that since I won't race it isn't at all a big deal.

vad

08-15-2005, 06:24 AM

Muck,
Are you still looking for a center gear for your Hyper 7...? If so you can look into the Hot bodies lighting stadium truck, it has a 50T center gear, just get the whole diff assembly and it is a direct drop in.
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJBL1&P=7

It is a steel gear just to let you know. There is a place that can make Delrin gears but the gear must be drawn up in CAD software.

vad

08-15-2005, 06:28 AM

If any of you guys are good with CAD software, check out Emachines.com, they offer software where items can be designed and made out of most any material, They even have Delrin. Im trying to make a 52T gear, but it is difficult for me.

http://www.emachineshop.com/

tcolesen

08-15-2005, 05:31 PM

A while back I had made some parts using Emachine shop's software, and for low quantity stuff, the price was very high (even for something like a flat piece of metal with no design). I would suggest using their services only for higher quantities.
But good luck with that designing!

Gojira

08-16-2005, 11:43 AM

whats the easiest way to get a plastic spur set-up that works,any ideas

Gojira

08-16-2005, 12:15 PM

also anyone try the castle creations hv110 yet

tcolesen

08-16-2005, 03:56 PM

Gojira

08-16-2005, 04:04 PM

cool thanks ,thats what i thought about the mbx diff just was not sure

vad

08-16-2005, 10:46 PM

You mean a plastic spur on a differential? The easiest way is just to use the Ultra MBX's differential, and then just use the optional plastic spur.

The Castle Creations HV110 is an airplane controller. It is not at all suited for cars.

Is the MBX center diff a direct drop in..? Which cars can take the ultra mbx diff without modifications to the center diff mounts.

tcolesen

08-17-2005, 05:14 AM

As far as I know, it doesn't direct drop-in to any cars. I am pretty sure it doesn't fit onto the Hyper 7 without mods, but have no idea about any other cars.

buggie_boy

08-17-2005, 06:44 AM

will the Novak HV MAXX Brushless System work for a buggy conversion?

and can you run lipos with it?
thanks guys

tcolesen

08-17-2005, 01:15 PM

The HV-Maxx system is probably not powerful enough for a 1/8 buggy. The HV-Maxx has no low voltage cut-off for Lipos.

InitialVelocity

08-17-2005, 01:54 PM

If anyone is interested, I converted a Hot Bodies Lightning 2 Pro buggy to electric. I am running a 99.18, 7xl, and a 3200mah 11.1 volt Kokam lithium polymer. It runs like a dream, very smooth, no problems whatsoever. I'll post pictures later today and video later this week.

tcolesen

08-17-2005, 05:36 PM

That would be good to see. In my mind, 11.1v is really low for the 7XL. You could bump it up to a 4s pack, and then it would run even better!

Muck

08-17-2005, 11:08 PM

I just bought an Ofna MBX complete center diff off ebay for $19.99. Ebay prices seem reasonable. Hope I don't have too hard of time getting it into my chassis. I may just get a MBX chassis and dog bones like Mr Constructor suggested. If I have to go that route I hope all my other Hyper 7 parts fit the MBX chassis. I'll try to report back as to how well it fits.

Now I will need to find the Ofna spur gear. R/C Monster is out of stock on that gear right now. Does any one know the what the part number is? Is this it, Ofna 51 tooth spur (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBM16&P=7) ? Has the same description and good price too!

tcolesen

08-17-2005, 11:19 PM

That gear will fit.
There is also this one, don't know why it is so expensive:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBZD5&P=7

InitialVelocity

08-20-2005, 12:21 AM

Heres Two Videos of it:

http://www.rpm-photography.com/Videos/LakeClosed.wmv

The Next one is the original test run, its not running as it should.

http://www.rpm-photography.com/Videos/Pro2Video.wmv

glassdoctor

08-20-2005, 01:32 AM

Very nice video... looks good. The 18T is hilarious.

How does the setup run (temps of batt/esc/motor, run times) ?

sugs

08-20-2005, 01:54 AM

How about a picture of that cold fusion motor mount?

buggie_boy

08-20-2005, 03:44 AM

will the MGM Compro 120 amp, 12 cell brushless car controller do for a 1/8th buggy conversion the moter iam useing is Feigao 540 10L Brushless motor
or what would u recomend
thanks for your time

tcolesen

08-20-2005, 12:07 PM

buggie_boy - the MGM Compro will work with a 10L. It is a great choice for 12 cells.

InitialVelocity

08-20-2005, 05:21 PM

http://www.rpm-photography.com/Lightning2Pro/Lightning2ProMotorMount.jpg

sugs

08-24-2005, 12:43 PM

Thanks InitialVelocity! Now that photo brings up another question. Did you rotate the diff or is the motor mounted where the battery/receiver box used to be?

ducati777

08-24-2005, 01:05 PM

good eye, it does look like the motor is on the right.....

Rtsbasic

08-24-2005, 02:41 PM

Where'd you get the motor plate from? Did you make it?

InitialVelocity

08-24-2005, 04:03 PM

The Motor is on the battery/rx box was.

The Motor Mount was from Cold Fusion racing, and will be availble in the future in a much nicer form.

Rtsbasic

08-24-2005, 04:19 PM

Where could I buy it in its current form? Can't find it listed on their website. It looks fine for what I need it for, a lot better than my own mount plate.

mscjakes

08-24-2005, 04:54 PM

What ESC is everyone using with a 11.1 Lipo pack???Thanks Jake...Also What motor

tcolesen

08-24-2005, 05:25 PM

The MGM controllers have a built-in Lipo cutoff that can be set to hard cutoff or soft. Hard cutoff is where it cuts power to the motor completely until the voltage goes above 3v/cell. Soft cutoff is where the controller decreases the motor speed when it goes below 3v/cell. The Schulze U-Force also has a user-settable LVC using the computer interface.

External units can also be made. I am working on one right now that could potentially be user settable (for the low voltage cutoff that they prefer) that would cause the motor to stutter when battery voltage gets low. It goes between the controller and the receiver. I am even working on a version that has this LVC device AND an external BEC, with both on the same circuit board. I probably won't sell this, as my time may become limited, but if they work, and some people are interested, I will see what I can do.

Gojira

09-08-2005, 05:10 PM

need help my 9920 will not set up right,after following the directions it goes full throttle with the tx at neutral ive been trying to set it up for 2 days and it keeps doing the same thing im using a futaba 3pk someone please help im going....cccrrrraaaaazzzzyyy

tcolesen

09-08-2005, 05:30 PM

Are you using the high-speed setting on your 3PK? If you are, then disable (or do whatever you can do to get the regular transmit speed). Not sure if this would work (assuming you are using it), but it is worth a try. Also, is your throttle trim in the middle? Have you trie reversing the throttle channel?

Gojira

09-08-2005, 06:47 PM

i lied its a futaba 3 pm and ive tried just about every thing,BK's site says to use 4 cells for programming but the esc has 2 battery inputs should i use 2, 4 cell packs i dont know i should have gotten a shulze

Mr. Constructor

09-09-2005, 04:13 AM

have your receiver and your cryszals checked too, the bk esc´s are normally fully programmable when bec is switched on with a 6 cell pack !!
(look at the bec "switch" the small connector had to be pushed in, normally it is set to bec on)
The only thing to try is to check the crystals and test (if possible) with another receiver, maybe even withz another radio, as it might be sending wrong impulses to the esc.

the jumper had to be set into on pos. after having it re- programmed, only after this it should be turned on , or it will "forget" the written data.

if you wanna use the pc programming, only use a separate battery pack, as the esc will only go into programming modus with a 4 cell battery pack hooked to the cable.

good luck, hopefully something might help.

Gojira

09-10-2005, 04:21 PM

thanx TC and MR.C but still no luck i may just send it back

fasteddie9111

09-22-2005, 10:12 AM

hi,
i have been out of the r/c seen for a little bit. I was wondering if anyone is/knows someone that is running a non-brushless 1/8 buggy conversion? what is the setup and what is your opinions on it? thanks.

Gojira

09-22-2005, 10:18 AM

i dont know anybody running brushed motors in there conversion but it is possible,ive even thought about it.Two trinity 17t should be pretty fast in an 1/8 buggy.The emaxx motor plate should make it real easy to mount two motors

Mr. Constructor

09-22-2005, 05:25 PM

with my conversion kits you´ll be able to run any 540 sized or even a 550 sized motor OR the 540 sized BL motors, it´s left upon you, your choice !!
(i tested one of my protos with a rubbish 540 mabuchi on 12 cells, it ran OK, but not that much fun if compared to let´s say a mild bl setup !! the reached speed was around the 30 km/h at a slightly good driving time of around 10 min!!
(but bl delivers the same driving time with 2x the speed.)

it is off course possible with any car, but as these 8ths weight a lot mostly the 1/8 " shafts of the 540 sized motors break to often, the bigger neodymyum ones from graupner or plettenberg are a good choice for cheap entry they deliver much more power in those cars, but need maintenance too, the power is around 85 % of that of a similar BL car, the mabuchi is around 35 % !!!

Muck

09-22-2005, 05:58 PM

tcolesen

09-22-2005, 07:21 PM

Go for the MGM 160amp. It can handle more amps, which means that it would run cooler. Also, I would suggest that you run 4s Lipo instead of 5s, as it is best to have a motor in a 1/8 buggy spinning at about 30,000-35,000RPMs loaded. The 5s Lipo would probably cause the motor to get hotter than you would like. I have a similar situation with my 1/8 buggy and a Feigao 8L - on 4s Lipo, the motor gets really hot, and I have to give it a break. If I run 3s Lipo, the motor runs at a very comfortable temperature. Even if 3s Lipo doesn't supply the same power, it is still good enough for me. Sometime soon I plan on getting a Feigao 7XL to run on 4s Lipo. With a powerful motor like that, I should be able to gear up high enough to give me lots of speed (as long as the controller doesn't overheat!).

vad

09-23-2005, 12:12 AM

Ok,
I've got my hyper 7.
Got the mbx center diff and plastic spur (which I still have to fit in).
Got a 10L Feigao motor.
I'm thinking of using a 5s lipo pack.

What controller?
I want a good controller. I figure my choices are:

Schulze 18.97 kw (I would have to get a seperate lvc).
MGM 160 amp controller.
BK?
Any others?

Muck,
You could have ordered the hyper 7 diff adaptor from JT racing. This will allow you to mount any plastic diff gear to the Hyper 7 diff will require a little modification, but then installing a mbx center diff in the Hypr 7 will require modification as well.

Mr. Constructor

09-23-2005, 05:08 AM

My quote: go for the MGM too, their new software is free of problems (so far i tested it, but i tested it on several motors, 2, 4, 6 and 10 pole )

the only "bad" thing on it: the 160A 16 cell (check that with your lipo´s, 5s isn´t possible then !!) esc has only an optocoupler, wich means you need a separate bec unit for these cell counts !!
Take this in account as those bec units might cost a bit more than first expected !! (anyway, the other esc´s like schulze or bk will need this bec unit too)

Muck

09-23-2005, 01:30 PM

I think I will start off with 4s, then later if I could always go up to 5s. I'm glad Mr. Constructor that you mentioned that I would need a bec with 5s. I have an extra ubec just in case. I wouldn't have known otherwise.

Muck,
You could have ordered the hyper 7 diff adaptor from JT racing. This will allow you to mount any plastic diff gear to the Hyper 7 diff will require a little modification, but then installing a mbx center diff in the Hypr 7 will require modification as well.

Good to know about JT racing. I have not heard about the diff adapter for the hyper 7. As far as installing the mbx center diff, It looks like I can move the back diff holder post (or whatever it's called). I can move it towards the rear of the vehicle to accommidate the larger mbx center diff. Then use the shorter mbx dog bone. It looks like that will work, but I have not tore into it yet. It's still burning nitro at this point.

The MGM controller is looking like the one. What about the fact that it is kind of a open design and might need to be sealed up?

Mr. Constructor

09-24-2005, 07:16 AM

it´s the typical flight esc design, so a very light sealing in the front and back with silicon could be done, but PLEASE not the full esc floating with silicon, only a few mm at both ends is OK and will seal it against debris.

tcolesen

09-24-2005, 10:05 AM

Mr. Constructor, have you seen the newer MGM controllers? They are a new "cube" design that have an actual heatsink on top and bottom of the controller. Instead of wires coming out, it has 3.5mm gold plugs to plug your battery and motor into.

Mr. Constructor

09-25-2005, 04:41 AM

yes, you mean this design :
(the bottom is not sealed as there is a second bigger alu cooling head as this design gives a great cooling, and is way easier to mount, but costs more (i do not have any comparable prices up to now, but i was told that the difference wouldn´t be that high, but you´ll "feel" it a bit ;-) )

here´s a pic:

fasteddie9111

09-28-2005, 11:36 AM

hi,
i was wondering what is the average speeds you guys are getting with your brushless setups? it seems that a strong running (not over-geared) setup gets around 35-40mph. what kind of speeds do you think would be possible with something like a dual mag. mayhem running with maybe 8 cells? i have read about e-maxx guys getting above 30mph with these setups, but they are heavier and have more rotating mass. what do you guys think?

vad

09-28-2005, 01:28 PM

Guys I need help in making a delrin gear....

please look at the following snap shot of the screen and can I get suggestions of what pitch and backlash should be. I so far I am using 25.4 pitch and backlash I have it set at 5%. I made a gear to fit the JT diff adaptor, but would like to get the pitch and backlash right before I send off to have it made.

Mr. Constructor

09-28-2005, 02:56 PM

vad

09-28-2005, 06:32 PM

were did you get this from ???
(as most of us are searching for a source where we could get our "own made" gears)
As for the pitch, it´ll be ok with 25,4 mm wich means the pitch will be 1 inch, that´s so far good, but the backlash surprieses me, g me little more details an i might be of help for you ;-)

see ya

Robert,
I got the program from Emachineshop.com, they will also be the ones making the gear. I am thinking of having the gears made with the injection molding process. I now have the JT racing center diff adaptor and finally figured out how to make the gear on the CAD program. I just want to make sure I have the numbers right before I get the gears made. I will start out with a prototype and see how it comes out, then I plan on getting more gears made out of Delrin 50T, 53T 56T and 60T and being 6mm think. With the JT adaptor makes gear changing a breeze in the Hyper 7 pro. Additional note, the hyper 7 diff fits in the kyosho mp-7.5 / 777 line up, and the hot bodies lighting series of buggies and truggies.

vad

09-28-2005, 06:33 PM

Mr. Constructor

09-29-2005, 06:32 AM

OK i see the point as i had first to translate it to german, now i fully understand what backlash means.
The needed backlash should be around 2-3 % as it describes the play (or tolerancy) the gears will have, a finer backlash means more costs i think (as the mold has to be finer cutted), so go for a good middle section, i would select 3 % wich is way enough for our rc car purposes !!
(if the play is too less you might get failures too, as most rc parts are of a middle quality compared to the possible solutions that are manufacturable.)

Gojira

09-29-2005, 07:13 PM

anybody know if its possible to run 2 motors off of one esc,im talking about brushless,like if i had two motors rated at 30a could i use an 80a esc and run two of them.just wondering thanks

tcolesen

09-29-2005, 10:09 PM

It might be possible if they are connected to the same spur gear. But, during bursts, the motors may pull too many amps (it's possible). It isn't reccommended to do this because the motors most likely won't have their rotors in the same position, and since the controller can't detect the rotor position of each motor separately, you could run into problems. But if you want to try it, you very possibly could get good results (just don't surpass the current limits of the controller you choose).

Mr. Constructor

09-30-2005, 06:18 AM

IF you are extremely fine in adjustments it IS possible !!
(there´s a small trick on that, feel free to send me a mail !!)
(i´ve posted it in my other threads, i did a full race truck this way with 2x 19L motors on one esc and one spur gear !!it functions flawless till today !!)

but normally this method leads to too high weighted cars and the esc has to have power too, 2x 30A means a 80 A at minimum, the bursts might even go further than 100A !!!

Gojira

09-30-2005, 06:51 AM

the reason i asked is because im thinking of building a ducted fan powered car , be for you ask its just for the hell of it. lol

Mr. Constructor

09-30-2005, 06:58 AM

the ducted fan idea isn´t what makes me wonder . . . (i´ve seen bicycles with a jet engine, some crazy people of a german flight club did this a few years ago, they hit 80 km/ and even more, but the driver was afraid of !!)

so this isn´t the thing, the ducted fan idea is really good, but as you might have found out hard to do, but why 2 motors, go for one bigger one and maybe split the ducted air if needed, it´ll be a lot easier to do i think !!
(will then be like a 3d vector jet control system with several tabs leeding the exhaust to the direction you wanna fly (in planes used in high tech testing areas, prototype status)

GriffinRU

10-15-2005, 12:16 PM

tcolesen

10-15-2005, 02:59 PM

That's an interesting motorplate! I am curious though why you have a mechanical brake on there.

GriffinRU

10-15-2005, 05:16 PM

That's an interesting motorplate! I am curious though why you have a mechanical brake on there.

Motor plate works as heatsink for motor by transfering heat to main plate.
As well to work with pinions from 12 to 18 tooth.

As you know this one has center differential, so to apply brakes on both front and rear you need to use both mechanical and electric brakes. Which works great and you can tweak them independently and even set brake servo on separate channel if you wish.

Artur

GriffinRU

10-16-2005, 12:52 AM

I am new on your forum... but here is my Mugen mbX5 prospec buggy
More pictures and projects here http://www.rcuniverse.com/gallery/galleryCat.cfm?memberId=193195

If any need a conversion kit, they will be available soon.

Artur

Budget version with Novak HV4400

tcolesen

10-16-2005, 01:24 AM

Does it run at all well with the HV? I would think that the buggy would be murder on that system.

sugs

10-16-2005, 11:11 AM

Yeah, I'm curious too how well the HV moves that buggy. Enough power to club race or just for bashing.

GriffinRU

10-16-2005, 11:17 AM

Does it run at all well with the HV? I would think that the buggy would be murder on that system.

Explain your point.
Sensored motor would be the best to have on any car-type application.
I can find industrial motor with sensors, but then need to adapt/design controller around it. (Not a task everyone can reproduce). So I was putting parts which are easy to get and put together.

So far the weak spot is pinion gear, which is hard to find to match straight cut spur. Probably will make an adapter to mount on differential to except true 32P or Mod1 Spurs.

Artur

tcolesen

10-16-2005, 11:19 AM

The HV-Maxx is rather weak compared to other sensorless setups, and struggles a little in the E-Maxx. I would think that it might have a tough time in a 1/8 buggy (it might get hot).

GriffinRU

10-16-2005, 11:46 AM

Yeah, I'm curious too how well the HV moves that buggy. Enough power to club race or just for bashing.

With 375W motor no chance to compete with 800W+ sensoreless setups or 1+HP nitro's, but It will give them enough challange in tight sections (towards Nitro).

But to give you more appropriate answer, in November I will have a chance to compare both systems side by side. I will share results.

Artur

GriffinRU

10-16-2005, 12:00 PM

The HV-Maxx is rather weak compared to other sensorless setups, and struggles a little in the E-Maxx. I would think that it might have a tough time in a 1/8 buggy (it might get hot).

E-Maxx twice the weight. (But not quite as fast :) )
In my setup motor has much better heatsink then in E-Maxx setup. But as all you know HV4400 motor has terrible heat transfer from windings to case, so that need to be solved by Novak or by hand (tough one).
I haven't overheated Novak's ESC yet in my other setups. But we will see what happen with this one.

Artur

P.S. By the way, in the past I was able to modify Novak's EVX to handle more than it is rated for (http://forum.rcdesign.ru/index.php?showtopic=15049&st=0&p=129175&#entry129175 I can translate later, but it is clear from pictures I guess)... HV4400 looks the same inside, so I do not think it would be hard to do the same with it as well. And HV4400 motor simular in size with XL-series motors (hacker, nemesis, feigao line), but with smaller rotor. So 375W sounds more on safe side rather then performance...

GriffinRU

10-16-2005, 12:21 PM

anybody know if its possible to run 2 motors off of one esc,im talking about brushless,like if i had two motors rated at 30a could i use an 80a esc and run two of them.just wondering thanks

Depends on spur gear size (more teeth better) it would work fine. Connect two motors together and spin one, second one will get in the right position.
The idea is to match rotor and winding locations.

Problems:- Less teeth on spur less precision (Efficiency and reliability - goes down)
- 2 Motors are not exactly matching each other, master and slave (Efficiency - goes down, one works harder)
- ESC will have higher minimum stable RPM's (Good-Bad ?)
Benefits:
- In some cases lighter and better fit
Recomendations:
1 sensored Master motor and sensorless Slave.

Artur

P.S. 4 and more pole motors tighter requirements on spur or whatever you use to tie them together.

glassdoctor

10-16-2005, 03:08 PM

GriffinRU

10-16-2005, 06:22 PM

[QUOTE=GriffinRU]E-Maxx twice the weight. (But not quite as fast :) )
QUOTE]

Stock emaxx is only about 10% heavier than an electric 1/8 buggy. :)

I think the concern with the HV is the wind of the motor.... kv is pretty high for a vehicle without much gear reduction. Emaxx has plenty of gear reduction (like 30:1) for a high rpm motor but a typical converted 1/8 is stuck with 10-15:1 range.

Pardon me, but E-Maxx has monster size tires (heavy and bigger diameter) and my buggy doesn't weight 9+lbs.

Do the math and you will find out that to be in 44-60MPH with 14.8V Kv should be around 3000+/-1000 with available optional pinions(10,12,13,14,15,16,18) and spurs(44,46) plus optional main diff gears. If you treat HV4400 as hottest motor then you should be Ok.
Again define your goals and pick the right combo.
So far I had no trouble running 6.5lbs+batteries buggy with stock (11.79) ratio. But testing is still in process. Any side effects will be shared.

Artur

glassdoctor

10-18-2005, 09:49 AM

Easy... not trying to ruffle feathers here. Just keeping things in perspective.

I talked to the guys at Novak before they released the HV and they were testing it in a 1/8 buggy. I never said it won't work. I just don't think it's ideal... I think a lower kv motor is better suited, that's all.

I have a BL emaxx and I have done more than one 1/8 buggy conversions. A buggy runs about 8lbs and an emaxx is about 9lbs unless it's an all aluminum 18+ cell sled. Some emaxxs are 12-14lbs... but most will be under 10. Yes... tires are a bit bigger and heavier. And gearing is lower.

Most of my concerns with the HV actually come from experience with a 3000kv hacker motor in the emaxx. In general that's been shown that 3000kv is a pretty hot setup esp on more than 12 cells. Many emaxxs are running @2500kv motors. 4400kv is really high but should be fine if geared lower than other motors... but that can be a problem in a buggy.

BTW, I have crunched the numbers for a lot of setup combinations and I'm well aware of what rpm and volts etc should be required to run at x speed.

I have an 1/8 that runs 54mph on 4s geared 13/44 with a @2000kv motor... and +40mph at 10/46. I will admit though that I should test the car with another motor out of curiosity because the motor that's in it is a Hacker can with a Feigao rotor and the gps tested speeds seem too close the theoretical (100% efficient zero drag) #s.

We look forward to more test results with the HV... we have talked about them but nobody here has used one in a buggy yet. I almost bought one myself when my Hacker took a dump.

I have been wondering how the HV would perform on like 10 cells, or a lightweight 3s lipo setup. I think that could be very good... 12volts is plenty for that motor and a lightweight car will let that motor spool up easier. Two thunderpower 3s 2100prolite packs only weigh as much as 4 GP3300 cells.

GordonFreeman

10-18-2005, 05:38 PM

Fun thread! I've never done 1/8 scale before and I mentioned to a guy that does regular nitro 1/8 scale that I thought LiPo Brushless would be competetive and he didn't think so. So it's on now! The best way to get me to do something is to tell me it can't be done! OK, enough intro.

I want to make sure the 1/8 scale can make a 15 minute main and be a competitive machine (if not dominant).

I wanted to start by just figuring out how much energy is onboard a normal 1/8 scale and how much energy I should shoot for with a LiPo battery. Well I must be doing something weird with my calcs. Anybody see what I'm doing wrong?

My calcs say a 125 cc tank of nitro has 473 Wh of energy in it. (12MJ/kg for fuel). Now for a 14 volt 8000 mAh pack I only get 112 Wh of energy (do I just multiply the volts by the Amp-hour to get W-hr?)

I realize that a nitro engine is probably only 20-30% efficient so the actual energy to the wheels is only going to be around 100Wh. But it looks like I would need an insanely huge battery to make 15 minutes at race pace. Have you guys ever actually tried to compete in a real 1/8 scale race? If so, how long of run time are you getting with what batteries?

Rtsbasic

10-18-2005, 05:50 PM

Will a 1/8 buggy run 15 mins with only one tank of fuel? And can you use all the energy of a 8,000mah lipo in 15 mins?

GordonFreeman

10-18-2005, 06:03 PM

No they pit about every 5 minutes, takes about 3-4 seconds to fill up and go again. So they are actually using about 3 tanks of fuel or 1500 Whs of energy!

Again if we assume 20% overall efficiency (maybe it is less) for Nitro, they might be putting down to the ground 300 Whs of energy. By my calcs I would need a 14volt 22 Amp-hr battery to have enough energy on board to go 15 minutes.

Just wondering how practical these numbers are and if anybody has actually tried to race (as opposed to bashing) a brushless converted 1/8 scale.

For instance "racing/bashing" around in a parking lot I can drive my 1/12 scale for 25 minutes, but on high traction carpet in actual racing conditions I only get 8 minutes of run time.

I just don't want to get into this project only to find I need a $1000 battery pack to make 15 minutes of race time.

GriffinRU

10-18-2005, 06:19 PM

Easy... not trying to ruffle feathers here. Just keeping things in perspective.
...

No "feathers here", just sharing... :)

As I mentioned earlier HV4400 "budget" version and wasn't the goal of this conversion. But I will try to play with it for now and give you some details.

As for 10 cells or 3LiPo, it is not going to work with HV4400 because RPM will never reach motors power band, efficiency with performance will be low.

Any input and comments are welcome here.

Meanwhile HV4400 with 46t spur and 12t pinion performs not as good as 8L brushless and pinions do not last at all. So adapter plate is coming soon.
Also I am looking for Aveox (Feigao?) sensored motor to use instead as a backup plan.

So far here are the problems with conversion:
1/8 shaft (not strong enough for heavy-duty abuse) HV4400 only
Spur an pinion mismatch Both systems
Not enough room with HV4400 ESC to accomondate all pinions HV4400 only

Artur

GriffinRU

10-18-2005, 06:28 PM

GordonFreeman

10-18-2005, 06:34 PM

8000*4*14.8=473.6W.

Artur

The 4 in your equation is 60 minutes/15 minutes? Don't the 1/8 scale Nitros have more like 2 horsepower? (of course the power band sucks probably)

But you think a 14.8 (4cell) 8000 mAh would be in the ball park? That's only a couple hundred $ I think.

GriffinRU

10-18-2005, 06:49 PM

The 4 in your equation is 60 minutes/15 minutes? Don't the 1/8 scale Nitros have more like 2 horsepower? (of course the power band sucks probably)

But you think a 14.8 (4cell) 8000 mAh would be in the ball park? That's only a couple hundred $ I think.

Yes, 4 is 1/4 of hour.
And some of them even 3+HP :)
With 15-20C discharge rate, I think that would be the good pack to start with.

Artur

GordonFreeman

10-18-2005, 06:56 PM

What would be a good ESC? I have an Mtronik Genesis Pro, it's rated for 4 cell at 100 amp peak. Anybody abuse this ESC sucessfully?

tcolesen

10-18-2005, 07:00 PM

The runtime you get with any battery will depend on the chosen motor (kv), the weight of the vehicle, gearing, and driving style. A 4s 8000mah Lipo would give you closer to 25mins of runtime than 15mins. Here is my reasoning:
-Average amp draw of 20amps (this is approximate, and pretty close)
-Battery capacity of 8amp hours

60mins * 8amp hours (60mins per hour) divided by 20amps will give 24mins. as the solution. So, my original idea of 25mins is not far off. You might be wondering how I came up with 20amps average draw. From my testing, I have found that my Feigao 8L (hot motor for a 1/8 buggy) will drain a 4000mah Lipo pack in about 10mins. This leads to an average draw of about 24amps. But since this motor isn't efficient for this application and will pull more amps than slower motors, its average amp draw is higher.

Yes, 4 is 1/4 of hour.
And some of them even 3+HP
With 15-20C discharge rate, I think that would be the good pack to start with.

Artur

But, brushless motors have a lot more torque than nitro engines do. So, it isn't all about horsepower :). But, these brushless motors can generate high HP during peaks. For example, a motor pulling 120amps with battery voltage at 12.5v (this could be a burst). That's 1500watts, over 2 HP, and not mentioning the added torque.

GriffinRU

10-18-2005, 07:59 PM

The runtime you get with any battery will depend on the chosen motor (kv), the weight of the vehicle, gearing, and driving style. A 4s 8000mah Lipo would give you closer to 25mins of runtime than 15mins. Here is my reasoning:
-Average amp draw of 20amps (this is approximate, and pretty close)
-Battery capacity of 8amp hours

60mins * 8amp hours (60mins per hour) divided by 20amps will give 24mins. as the solution. So, my original idea of 25mins is not far off. You might be wondering how I came up with 20amps average draw. From my testing, I have found that my Feigao 8L (hot motor for a 1/8 buggy) will drain a 4000mah Lipo pack in about 10mins. This leads to an average draw of about 24amps. But since this motor isn't efficient for this application and will pull more amps than slower motors, its average amp draw is higher.

But, brushless motors have a lot more torque than nitro engines do. So, it isn't all about horsepower :). But, these brushless motors can generate high HP during peaks. For example, a motor pulling 120amps with battery voltage at 12.5v (this could be a burst). That's 1500watts, over 2 HP, and not mentioning the added torque.

You do not need to convince me about electric power :)
But it is always about horsepower :) Torque=HP/RPM right?

Let's do some math...
wheels D=4.45"=.113 m (prefer metric)
gear ratio 11.79 (just for this case)
Kv=3079
Voltage=14.4

Max RPM=3079*14.4=44337
Speed at Max RPM=((44337/11.79) * (3.14*0.113) * 60) * 0.6=48.035MPH
RPM ratio PI whl.D hs kmh-mph
Now taking into consideration that voltage under load will drop, how that can be hot motor? But wheels expand as well...

Artur

P.S. Can be very possible that you have different numbers. But are we using the same math. And do not get me wrong, I am taking seriously your input and trying to get more field info.

GordonFreeman

10-18-2005, 08:20 PM

My experience is that Power is the first thing you look at. What power do you need at the wheels? (engine torque does not matter, power band does, but they are not the same thing). Once you've got the power required, you look at the the rollout (tire diameter, gearing ect) to find the engine torque required.

Within some reasonable limit a 5000kv motor that puts out 500 watts is going to perform similar to a 2500kv motor that puts out 500 watts if they are geared properly.

You can play with the battery voltage/amp capability Motor Kv/power and gearing and find all sorts of solutions for the same power requirements.

You're right, I would question the 20 amp average amp draw. 1/12 scale carpet cars (28 onches) average 30 amps (4cell NiMh mod (200ish watts?), 8 minutes)! And yes, the power band of electric is going to be a huge advantage! Electric motors put out almost constant power across the RPM range.

And I guess that's what I'm getting at, what is the average power requirement for a 1/8 scale under racing conditions? I know how much fuel they use and it's easy to calculate how much energy is in that fuel, what I don't know is what is the overall efficiency of the system? I'm guessing it's pretty bad, like 10%-15%. I know they are high compression engines, but I think over the whole RPM range they are pretty ineffiecent.

Just looking to get as much theory as I can to minimize my R&D costs.

tcolesen

10-18-2005, 09:29 PM

You do not need to convince me about electric power :)
But it is always about horsepower :) Torque=HP/RPM right?

Let's do some math...
wheels D=4.45"=.113 m (prefer metric)
gear ratio 11.79 (just for this case)
Kv=3079
Voltage=14.4

Max RPM=3079*14.4=44337
Speed at Max RPM=((44337/11.79) * (3.14*0.113) * 60) * 0.6=48.035MPH
RPM ratio PI whl.D hs kmh-mph
Now taking into consideration that voltage under load will drop, how that can be hot motor? But wheels expand as well...

Artur

P.S. Can be very possible that you have different numbers. But are we using the same math. And do not get me wrong, I am taking seriously your input and trying to get more field info.

The gear ratio I have been using is 13.23 (13/43 diffs, 13/52 pinion/spur). I am not sure what causes the motor to get hot, but it does. When I use 3s Lipo, the heat definitely becomes less of an issue. Many that have made 1/8 BL buggies would agree that 30,000-35,000 maximum RPM would be the best setup for motor speed. I have always taken this into account, and what I blame the motor heat on for when I use 4s Lipo.

Within some reasonable limit a 5000kv motor that puts out 500 watts is going to perform similar to a 2500kv motor that puts out 500 watts if they are geared properly.

You can play with the battery voltage/amp capability Motor Kv/power and gearing and find all sorts of solutions for the same power requirements.

You're right, I would question the 20 amp average amp draw. 1/12 scale carpet cars (28 onches) average 30 amps (4cell NiMh mod (200ish watts?), 8 minutes)! And yes, the power band of electric is going to be a huge advantage! Electric motors put out almost constant power across the RPM range.

Very true about output watts, but if you run the slower motor at a higher voltage, and gear both of the motors the same, the slower motor will be more efficient. This would allow the slower motor to be geared up slightly more to yield a faster speed if both motors were to have the same efficiency.

Those 4cell carpet cars have a high amp draw because of the high traction surface and the fact that they are lower voltage. A 1/8 buggy on 12 cells is getting 3 times the voltage, so its average amp draw is going to be lower. But if you say that these 1/12 carpet cars draw an average of 30amps but still getting 8mins, then you are contradicting yourself (with all due respect). If you were to deplete a 3300mah cell in 8mins, then the average amp draw would have to be about 25amps. So if a 1/8 buggy were to get even 10mins of runtime with 3300mah cells, then the average amp draw would be 19.8amps.

GordonFreeman

10-18-2005, 09:38 PM

All agreed, just change 3300 to 3800 (and realize they are actually higher than that, 500+ seconds @ 30 amps) and the math works out.

Higher Voltage, that's why I assume Castle is coming out with thier HV controllers, because using a low kv motor with HV is slightly better somehow. Can somebody explain the physics behind why that is so?

Can anybody else confirm the 20-25 amp draw (@14 ish volts) that an 1/8 scale would need in racing conditions? I was told by Mtronics that there is no way my Genesis Pro would work in an 1/8 scale, even though it is rated for 4 cell LiPo, 75 amp continuous.

tcolesen

10-18-2005, 11:36 PM

A low kv motor paired with higher voltage is better because slower motors run on higher voltage are naturally more efficient. Their kt (torque constant) values are higher than the faster motors, and instead of pulling amps to make power, they can use more voltage. If you were to look at Lehner's website, specifically at the data they have for their motors on different voltages and with different amp rates, you would see that the listed efficiency for the slower motors on higher voltage would be higher. I can't really explain the physics about that (maybe later this year, from AP Physics, LOL), but just looking at the data can tell you something.

75amps continuous won't be enough for a 1/8 buggy because the number of amps that the motor will pull can be much greater during bursts and peaks. It is during these bursts and peaks (when lots of amps are drawn) that the controller's resistance has a large effect on its efficiency. Let's say that a motor pulled 120amps for 3sec. A controller rated at 75amps continuous may struggle with this because it is building up extra heat from all of those amps. In case you don't know this, the heat buildup is measured in watts, and an equation would be watts=volts x amps x resistance. This measures the amount of heat released, so the lower the resistance of a motor or controller, the less heat that will build up from any given number of amps. This is the reason why you would see that a controller that can handle more amps than another will have a lower resistance.

Hope this helps :).

GordonFreeman

10-19-2005, 12:18 AM

Yup, no doubt on the running higher volt at lower amp can equal the same power as lower volt higher amp, just wanted to see some reason why it more efficient. Like you said, don't know the physics behind the fact. When I understand the physics behind something I remember it better. Maybe is it simply the RPM drag. I know that in air when you double your speed it requires 8 times the power. Or cube of the increase (2^3).

On the amp draw of an 1/8 scale, you're saying that the average amp draw might be 20 amp, but peak could be 120? I suppose we could estimate peak amps if I knew the traction levels. eg. an 8lb car that accelerates a 1G would require 8lbs of force at the tires, go through the gear calcs, ect. find the amps you need at what RPM. Can they accelerate at 1 G on dirt?

glassdoctor

10-19-2005, 12:48 AM

A good ballpark figure I follow is expect about 5 minutes runtime for every 2000mah battery. This has been my experience and it matches tcoleson's comments exactly also. 4000mah=10min.

For lipos I would figure an extra 20% more run time than you will actually need. This will extend their cycle life and performance and will help prevent overdischarge and self-destruction. 8000mah lipo would be a good setup for a 15 min. race and would probably run 20+ min max if you drive smooth and have an efficient setup.

1/12 scale 8min racing... how much mah is actually used in 8 min? (Nobody wants a setup that dumps the whole pack in the alloted race time or you would be dumping the last couple laps... ;) ) anyway.... let's say a 3800 pack dumps in 9 minutes. ( I think most guys would get 10-12 min on a 3800 pack wouldn't they? )

That's 25.3A average... and about 100W (25A x 1.0V per cell under load)

1/10 offroad modified class (6 cells) also typically runs about 25A average... and 150W

My emaxx with 12 cell C50 Hacker also averaged about 25A, but at higher voltage= 300W

I don't have a lot of track time with my 1/8 buggy but I did get 8+ minutes on a 3300 pack, trying to drive smooth and not just hammer down all over the track. Again, that calculates right at 25A average. I'm sure I can drive it hard and pull quite a bit higher average #s but I haven't checked that out, not to mention that the ESC tends to thermal before I can get a full run anyway if I run it hard.

I think my 1/8 would max out at 35-40A average in extreme racing conditions just based on runtimes I think I would get. I think I might be able to dump 3300 packs in a 5 min. heat... that would be nearly 40A ave. Can't see it getting any worse than that...

GriffinRU

10-19-2005, 09:14 PM

Well, let me see what I can do...

A little bit theory...

Electric motor performance can be presented by 3 graphs:
- RPM v.s Voltage
- Efficiency v.s RPM
- Current v.s RPM
Because of close to linear relation between RPM and Power (Voltage, Current) most electric motors can be characterize with Kv and Kt coefficients.

The best combo for any application will be motor with operational range at maximum or around maximum efficiency.

Now, not going too deep into theory, motors from the same size line (S-size, L-size, XL-size, 55mm, 65mm, 75mm ...) have the same rating POWER (Based on motor physical size). But having different number of turns can develop that power at different voltages/currents. (Hope this will help you understand why some combos working better and some do not...)
Motor with low turns has lower winding resistance, inductance and capacitance. Lower resistance means less heat loss, lower inductance and capacitance.
Less turns in field coils means lower magnetic field generated by those windings, which means less torque but higher RPM.
Now high turn motors has higher resistance in windings, higher inductance and higher capacitance (can be lowered with custom wiring as well as inductance).
But because they operate at lower currents resistance doesn't inflict high loss. And today's ESC can deal with high inductive/capacitive load at reasonable level. But if not then usually overheats due to the FET's failure to operate in true digital mode.
There is much more about motors and how they work and why some have wide/narrow power bands, higher or lower RPM's then others. But hopefully this would be enough to start.

So we can play, with any motor and gear and trucks, but until we get the right combo nothing will be good enough.

What we need for ultimate combo?

To select ultimate motor/ESC combo we should define next parameters:
1. Speed
2. Weight
3. Time
Now we need to calculate required power to achieve these numbers.
Power (kW/H) = (M (kg)*L (m) ^2)/T^3(H)
That is true power not including friction and transmission loss and lots of others. So to be true to real world multiply this equation by 4 and we will be close.
For an example let's do approximate calculations for 1000 meter run at constant speed of 40MPH for 1 hour.
6.5 lbs = 2.955 kg
40MPH = 64000 m/h = 17.77 m/s
Power = 4*(2.955*17.77^2)/1^3 = 3732.44 kW/h
(We can define dynamics later using acceleration formula L/T^2)
Average instant power for one second will be Power = 3732.44/3600 =1.037 kW/s. So to maintain 40MPH with 6.5lbs we need about 1037W of power (do not forget about coefficient 4... better vehicle efficiency, think about other parameters which can reduce-increase this number and you need less).

Now we need to select motor which will produce that power around maximum efficiency. Then this will be the ultimate motor.

Now having power and planning to run for 15 minutes you can define battery capacity.

So, how to find the best ESC for the job?
Less Operational Voltage - lower resistance, higher efficiency
Higher Voltage - higher resistance, lower efficiency (adding more FET's, smart FET's controls... helps but cost)
And we know that with higher voltage we always get more efficient system.
When choosing ESC you need to worry about continuous and peak current. I will recommend checking on braking current as well, because all of us are Ok with slow acceleration but we all want to stop fast :) Same energy would be dumped into batteries and ESC. So if your vehicle is heavy and goes fast do the math in opposite direction from above :)

One small comment:
Regular BL motor without heatsink cannot dissapate more then 30-50W without reaching extreme temperatures. What does that mean?
Max. efficiency of BL motor around 85-88%, then without heatsink maximum power maximum power available is (88%/12%)*50W=366.66W. Adding heatsink can improve this numbers, simple snap-on heatsinks with good airflow can allow to dissipate up to 100W - (88%/12%)*100=733.33
Now do the math with efficiency less then 88%...
And you do not need this power continuous (let motor to cool down)
Same thing applies to ESC, only their performance based on switching frequency and motor inductance/capacitance.

Artur

P.S. 30000-35000 RPM makes perfect sense for max. efficiency run and being able to get to 40000+ for a short period, during accelerations/passing...

glassdoctor

10-20-2005, 01:21 AM

I think we could spend years and fill volumes trying to define the single perfect setup for a specific application.

It's good to look at the laws of physics behind how and why things work if you can do so and have a background in it.

I've never really considered using such scientific methods to choose the mechanics of my r/c stuff beyond basics (like watts=currentxvoltage and xrpm=xmph etc.)... but then I don't have a background of using these formulas of physics and electrical theory. It's all good though and I like to see how the #'s are calculated... when they back up actual real world results.

Don't forget however to include some real world experiments to verify the accuracy of theory and calcs. It's easy to over-think things when working in physics and mathematics with pencil and paper... and not conducting experiments along the way.

For example... GordonF above mentioned calculating the gforce and traction etc to verify the amp levels during acceleration.... which is cool. But, we don't need to figure that out in theory or on paper because the actual reality of recorded telemetry data showed those #s.

x motor + x battery + x vehicle etc = x current levels, x speed, x runtime etc

These test reports are invaluable... I guess I need to get a data recording device too so I can get some #s to add to what others have posted.

I wish I had been keeping records of all the test results of those in these forums and my own limited test data.

GordonFreeman

10-20-2005, 01:57 AM

Well, let me see what I can do...
Power (kW/H) = (M (kg)*L (m) ^2)/T^3(H)

OK, lots of stuff for me to think about. Most of it makes sense, but I'm not following your power formula. Power is Watts (or horsepower) not Watts/time. And the right hand side I'm not following either. Nor the multiply by 4?

Power = Force * Velocity.

For a non-accelerating vehicle the weight (mass) has very little to do with the power requirements. It effects the rolling resistive force, but that is negligible at speed. Here is link to a spreadsheet I made for top speed calcs:

http://forums.radiocontrolzone.com/showthread.php?t=206604

The significant power requirement for an accelerating vehicle comes from it's mass. Force = mass * acceleration (aint Newton great?), and Power = Force * Velocity (in an atmosphere and well below the speed of light ;) ). If my buggy is 4kg and I'm moving at 6 m/s and I can accelerate at 1G (don't know what a buggy can accelerate at, just guessing, metric conversion from 1 G is 9.8 m/s^2).

Intuitively the Force required to accelerate a 4kg (8.8lbs) buggy at 1 G is 8.8 lbs of force, or 39 Newtons. (just an intutive double check to make sure the metric units come out right, I'm a unit freak!), so...

The Force required to accelerate a 4kg buggy @ 1 G (9.8 m/s^2) is 4kg*9.8m/s^2 = 39.2 Newtons.

Now for the last part, P=F*V, so P=39.2 N*6 m/s = 235 N-m/s or 235 Watts (1N-m/s=1 Watt). Metric rocks! Can't we just do away with Standard units already (along with brushes and the qwerty keyboard, whoops that's a whole 'nuther rant)?

Now to be more accurate the Force side of the equation also needs to have the tractive force added to it, which is made up of aerodynamic drag and rolling resistance. Rolling resistance can be neglected, but as speeds increase you must consider the aerodynamic drag, but at 6 m/s I would imagine it is minimal. But I've gone this far so let's just double check that we can ignore aerodynamics at 6 m/s.

D = Cd*r*((V^2)/2)*A, where Cd is drag coef., r is air density, V is velocity and A is frontal area.

Lets guess at the Cd and say .5 (a Hummer is about .57)
r = 1.186 kg/m^3
V = 6 m/s
A = (255mm wide by 150mm tall?) = .038 m^2

So D=.5*(1.186kg/m^3)*(((6 m/s)^2)/2)*.038m^2 = .4 N (again metric rocks!)

So at 6 m/s the aerodynamic drag is .4 N (compared to the 39 N of force required to accelerate the 4kg buggy, so it is ok to neglect the aerodynamic drag at that speed.

So it is ok to say that a 4kg buggy @ 6m/s needs about 235 Watts to accelerate at 1G. Now that number pretty close to absolutely correct AT THE WHEELS! We could add in the power required to accelerate the drivetrain-wheel, but let's not and say we did. The rotating masses come into play at low speeds but not so much at high speeds (not that 6 m/s is high, I just picked that as a medium-average speed for racing conditions).

What you need from the output of motor is dependant on driveline losses. What you need to input to the motor is dependant on the effieciancy of the motor, ect.

Let's assume 90% efficiency of the driveline and 80% efficiency of the motor. So the motor needs to be able to put out 235W/90% = 261W. The ESC needs to be able to put out 261/80% = 326W.

So, from my point of view, the only variable I don't know, or can only guess at is what can an 1/8 scale buggy accelerate at? 1G? I have acceleration data that my 275hp TA (3600lbs) can accelerate at around .7 G in 1st gear. My CBR900RR accelerates at about 1G before the front wheel lifts up. I would imagine a 4wd buggy would accelerate in that neighborhood (it's a nice neighborhood ;) )

Once you know what acceleration you need, you can work back to find the power needed. Then depending on what voltage you want to run you can calculate the amps needed, and if you know how long you need to run then you can find the battery size needed, as Griffin stated. I just don't understand your power equation.

I know sometimes I beat theory to death. I think there's a phase, "There comes a time in every project when you have to shoot the engineer and start production", or sometime like that. ;)

And part of my problem is I've never driven or raced and 1/8 scale before, otherwise I would probably have a better judge on the acceleration. You could, at the very least, measure the acceleration over 50 feet or something, to get a good estimate of traction.

It does seem somewhat surpizing to me that the actual power requirement are not as high as I would have though. On the experimental side, I did just run a 1/10 scale 2WD buggy (in race conditions) for over 25 minutes on a 3 cell 3100mAh battery!

Nitro guys - Look out!

glassdoctor

10-20-2005, 03:09 AM

1. I know sometimes I beat theory to death. I think there's a phase, "There comes a time in every project when you have to shoot the engineer and start production", or sometime like that. ;)

2. And part of my problem is I've never driven or raced and 1/8 scale before, otherwise I would probably have a better judge on the acceleration. You could, at the very least, measure the acceleration over 50 feet or something, to get a good estimate of traction.

3. It does seem somewhat surpizing to me that the actual power requirement are not as high as I would have though. On the experimental side, I did just run a 1/10 scale 2WD buggy (in race conditions) for over 25 minutes on a 3 cell 3100mAh battery!

Nitro guys - Look out!

1. yep. :)
2. thought so ;) btw, there have been a lot of acceleration graphs in rc mags... and don't forget BL will accel. faster than nitro.
3. that's impressive... what motor did you run? I assume it was a mild wind (and a gentle trigger finger) to work very efficiently with the high voltage battery. Even with the higher energy capacity of a 11.1V batttery that is incredible runtime for a 3.1AH battery.

Oh... and track conditions always vary, so the theoretical acceleration requirements really can't be quantified. Imagine building a drag car based on the traction in your driveway and then getting to the drag strip and realizing your shoes stick to the surface like glue. That's how they get to 320mph in 5 seconds.

Point is... it might be easier to just find the end of the rainbow...

GordonFreeman

10-20-2005, 03:17 AM

Feigao 3808412S. Geared 16/87. Tracksize, maybe 80x40?, 15.5 second lap times. It's small enough and medium traction so you only get to full throttle on the back straight and for only a split second. Buggy is about 250 grams underweight! (1250 grams), totally illegal! But I'm only experimenting and they know that.

I just measured the voltage in the pack and it's still at 11.3!!!! I would have kept going but I let somebody else drive it and he didn't understand the concept of studder (from a stop) and the damn thing decided to studder and he kept the throttle clamped for a few second and smoked the ESC (a little Mamba 25!) It was a pretty neat fire though. Everybody was impressed the fireworks! I still smell like burnt electronics. Think I can get Castle to replace it? :o

glassdoctor

10-20-2005, 03:22 AM

Ouch!

I see. A buggy that light would run a lot more effeciently for sure. Pretty cool setup.

GordonFreeman

10-20-2005, 04:00 AM

Just to beat a dead horse. Let's do a dragster calc.

Assumtions:

1. 1000kg car
2. 4 G average acceleration
3. Average speed 100 m/s
4. ignore aerodynamic drag (as if you were accelerating in space) and rolling drag.

Time to crunch: 1000kg*9.8m/s^2*4G*100m/s=3.9MW or 5200 HP.

Pretty close rough calc I think. Technically we need to graph it from 0 to 350 MPH and include the aerodynamic drag to find the peak power required, but again at 4Gs of acceleration the major forces come from the mass of the car. Doesn't matter if it a buggy, a minivan, an F16 or a rocket ship all these equations apply and can be used with the proper assumtions.

glassdoctor

10-20-2005, 10:51 AM

I can't say I follow the formula... but I'm curious where do you get the formula? and where you get the assumed numbers to start with in the above example like the 4G?

Does this formula calculate 4Gs at 100m/s? What does it calculate Gs at the starting line with 5200HP?

5200hp would be able to accelerate at 4Gs for how long?

Oh, is there a forumla to figure acceleration curves with a given HP and G force?
5200HP+4Gs= (x) seconds 0-60 or 0-100mph?

Now... what relationship is there between accleration at the 10ft mark and at the 1000ft in less than ideal traction conditions? For racing in the dirt you might not always have great traction to get off the line but you still want the HP as if you were running on concrete.

GriffinRU

10-20-2005, 06:34 PM

OK, lots of stuff for me to think about. Most of it makes sense, but I'm not following your power formula. Power is Watts (or horsepower) not Watts/time. And the right hand side I'm not following either. Nor the multiply by 4?

Well, I was trying to put something together... You did much better job.
As far as my formula, I was trying to make it simple, doing calculation on RC scale. And I was more interested in how much energy/power requires operating at given speed for given time. Not taking into consideration other parameters as acceleration, braking, free rolling, friction, drag... which have been replaced with coefficient 4. (Assuming that at the end sum of all these impacts will be equal to multiplication by 4, very relaxed statement). Also for me this formula was more attractive if you treat traction, dynamics and other impacts as change in mass. Operating with kinetic and potential energy.

As far as theory and practice, I prefer to build and run as well :)

Artur

GordonFreeman

10-21-2005, 02:19 AM

Yea, at this point it is probably time to "shoot the engineer".

Some detail info about power calcs based on mass, acceleration and Velocity:

Classical physics, Newton's 2nd law states that Force (Newtons) = Mass (kilograms)* Acceleration (meter/second squared). This is intuitive. If mass stays constant and you increase the force the acceleration will increase. It's an easy equation to play with the numbers to see what is happening.

Energy is a specific amount, like Joules or N-m. If I push with a Force of 1 Newton for a distance of 1 meter I've expended 1 Joule of energy. Energy can be Force * Distance. (or Amp-hours, Watt-hour, or calorie)

Power is energy expended per time. (that why Americans like power!). If you expend 1 Joule of energy in 1 second your are using 1 Watt of power. Or if you expend 10 Joules of energy in 10 seconds you are still using 1 Watt.

The equation Power = Force * Velocity, is derived from Force = mass * acceleration and Velocity = distance/time. There's a little bit of algebra to get there.

Power = Force * Velocity = (mass*acceleration) * (distance/time)

I don't know the specifics of a drag car acceleration curve. I think it varies a bit, and I think it actually can increase near mid track due to downforce giving more traction.

If you have unlimited traction, the accelleration at from a dead stop is infinity. Look at the equation. Do some more algebra to solve for a:

P = m*a*V so a=P/mV, So if either mass or Velocity is zero, acceleration is infinite. Since mass can't be zero and there is no such thing as unlimited traction, there is no such thing as infinite acceleration.

Yea, don't get confused about 4Gs at 100 m/s, if you're not accelerating, but you're moving at a constant 100m/s, there is no G-force. What I was assuming is that around 100 m/s a drag car might have the ability to accelerate around 4 G, from there we can calculate the power needed to accelerate a 1000kg car at 4 Gs at a (split second) speed of 100 m/s.

Just looked up some top fuel info, jaw dropping:
http://www.automobilemag.com/columns/0403_americandriver/

What's neat about this is that nowhere in any of these equations do I need to know engine torque! Only power. You don't need to know the wheel size, gearing, wheel torque or voltage either, just power. Once you know the power requirements you backtrack through wheel size, gearing, voltage ect, to find what motor you want.

Again, I've blown this completely out of proportion for a little fricken toy car. But I think I understand what is going on better now too. And I can be more confident in the battery/motor selection. I would think I could get a first guess within 10% of what I would need. I just didn't want to get 90% through this and find out I need a $1000 battery that I can't fit into the chassis.

Somebody mentioned about some 1/8 scale accelleration chart in a magazine, which one? Can they be found online?

sugs

10-22-2005, 12:44 AM

I don't know if they can be found online, but Xtreme R/C car magazine usually does an accelleration graph for every car they test, including 8th scales.

Muck

10-23-2005, 10:58 AM

Muck

10-23-2005, 11:00 AM

Piggyback Hyper 7 center diff.

Muck

10-23-2005, 11:03 AM

Anyone else's work bench this messy?

My buggy won't look as clean as it does now after I get the controller and receiver mounted.

tcolesen

10-23-2005, 11:06 AM

Way to be unique! I have never seen a plastic spur fit onto a diff like that... Which motor and battery are on there?

Muck

10-23-2005, 11:12 AM

It's a 10L and a Polyquest 4s 4400. I have to mention that the battery does fit perfecly in the AE cups too!

Muck

10-23-2005, 11:17 AM

If anyone wants the details of drilling the spur gear. Please let me know. I might be able to help. It did require a drill press and dremel.

GriffinRU

10-23-2005, 12:36 PM

I've been working on my Hyper 7 conversion this last week. Thought I would post I few pixs.

The MBX center diff was going to be a lot of mods and presented a problem because it is longer than stock. I decided to piggyback an Ofna 51t plastic spur on the stock steel spur. The 51t fits almost perfectly over the stock center diff housing. The toughest part of going this way is drilling through the stock spur. This turned out to be quite a challange. After hours of grindind, drilling and trips to the hardware store for more drill bits and more drilling. This is what I ended up with.

Loosen the hardened spur by heating up (to glowing red) and then let it slowly cool down. Then you will be able to cut through it like butter.

As far as 10L, 51 spur and 14.8V I am confused what the ratio comes out and speeds/dynamics?
For high Kv motor would be great.

Great place for motor! How is side by side weight distribution?

Artur

P.S. My new pinion, cut from original gear with pressed SS hub...

Muck

10-23-2005, 01:28 PM

Nice pinion. That looks like it would work well. I wish I would have known about heating the steel spur up first. I did it the hard way I guess.

I forgot to mention I'm starting out with a 12t pinion. The speed should be in the 30 to 35 MPH range. Weight balance at this point is slightly heavier on the battery side. I'm hoping to balance it out a little more by putting the controller and receiver on the other side.

GriffinRU

11-07-2005, 06:29 PM

I do have more adapters now.

http://forum.rcdesign.ru/index.php?act=Attach&type=post&id=17027

Artur

sugs

11-08-2005, 11:33 AM

Those only fit the mugen, right?

GriffinRU

11-08-2005, 06:03 PM

Those only fit the mugen, right?

You probably correct, but if bearing size and diff. height with mounting holes matches Mugen MBX5 then it might work.
But I do not know for sure.
What you can do, is to pick up Mugen MBX5 diff. housing (bottom half of the rear end) and compare it with yours. That would be perfect comparison test.

Artur

Gojira

11-08-2005, 06:12 PM

or u could just use an mbx diff in your conversion but youll have to drill some holes

tcolesen

11-11-2005, 10:44 PM

For those that are looking for an awesome setup for a 1/8 buggy, I would strongly recommend a Feigao 540C 9t (~2700kv) and a Mtroniks Truck controller. On 4s Lipo, this setup screems, and everything stays cool for what it does. My gearing for my XTM X-Terminator is 13/52. I run a custom slipper clutch modified from the Revo's slipper clutch, and the spur is a MGT mod1 spur. The diff ratio is 13/43, so my overall gear ratio is 13.23:1.
The motor has its own cooling fins, and can be taken apart via the screwed-on rear enbell that is secured by a set screw. For $80, you really can't go wrong!

GordonFreeman

11-11-2005, 11:32 PM

Where can I get a Feigao 540C XL in the 800-1000 kv range (9S LiPo, yee-haw!). Is there such a thing? XL might be overkill, but I figure it will run cooler.

Mr. Constructor

11-12-2005, 04:21 AM

yes, they might run cooler, but their outer diameter is a lot bigger than now, as the cooling section was added.
In some ways better than getting less copper for magnetic field strenght, but the use of cooling clip on heatsinks is better in my eyes on the older motors, the colling is there, but they´re smaller in diameter, so the cg or room needed will be less, the clip on heatsinks could be "adjusted" to the area where the most heat transfer will be needed.

Anyway, that´s the reason i would go with the normal 540 sized motors and then check the temps and specially place the heatsink where it is needed.

Gojira

11-12-2005, 08:22 AM

Where can I get a Feigao 540C XL in the 800-1000 kv range (9S LiPo, yee-haw!). Is there such a thing? XL might be overkill, but I figure it will run cooler.
check starluck http://www.starluckrc.com/catalog/ but you realy only need an L not an XL my buddy has a hyper 7 with a 10L on 4lipo it flys when it runs, he doesnt want to listen and hook up a u-beck so his esc keeps thermalling its a 99/20 i told him if he keeps driving it its going to catch on fire but he dont listen

Re-Mix

11-13-2005, 12:53 PM

Constructor, do you have a list of all the cars you make a conversion for perhaps? Thanks.

Mr. Constructor

11-14-2005, 05:54 AM

No Probs, here it is:

King of Dirt Buggy 4WD
Lightning 1 Buggy 4WD
Lightning 2 Buggy 4WD
Lightning Stadium Truck
Rockwilder 4WD (a Truck, based on the Lightning 1 available in two different lenghts)
Ofna Ultra LX Buggy 4 WD
Ofna Ultra MBX Buggy 4WD
Storm Buggy 4WD
SUT Truck 4WD
XB 8 Buggy 4WD (incl. the XB 8 R version)
Losi Super Truck 4WD

Will be finished in the next Time:

XTM Buggy 4 WD
Picco 4WD 8th scale On Road Car
Trike on Lightning 1 Chassis Base (will soon be available for all other Chassis too)
Lightning 6WDS Crawler, has 3 axles, all fully damped, isn´t longer than a Truck Version, but offers great climbing action, for Rock Crawling)

Are in the planning:

Mugen MBX 5
Caster Racing ZX 1
Savage Truck (6-24 cells !! but only 30mm longer !!)

Generally there are 3 Versions for each Buggy to choose from:
1. Buggy conversion Kit, wheelbase 330 mm, Motor lenght up to 60 mm, 540 can sized Motors, 6-12 cells
2. Truck Version, this Kit will have a wheelbase of up to 370 mm, it offers Motor lenghts of up to 70 mm, 540 can sized Motors, AND Batterys from 6-14 cells
3. near by 6th scale conversion, designed for the 6th scale bodys from ofna or carson, wheelbase around 400 mm, chassis could take up to 20 cells !!, Motor could have a lenght of up to 80 mm then, ultra light weight 6th scalers are possible with this setup.

some cars are available in special conversion kits too, the lightning will be the first to be converted to a 6wds or a trike too (the other chassis will get the trike conversion too, but not (due to technical reasons) the 6wds)
the lst conversion is only available in 1 style, same with the picco.

all chassis (except the 2 above) could be used with a spool center shaft (standart in the kits) or with a slipper clutch as an option, even a 3rd diff is in the planning)
Some cars could be ordered with a special power increasing drive tranny extra that you will have more power, but less rpm, this is ideal for trucks with very big tires, or heavy constructions anyway.
the special truck drivetrain could be also combined with the slipper clutch too.

this thing is only available to the XTM Trucks or the SUT at the moment (this is due to technical reasons, the others could not handle it, sorry)

but as you see, there are so many option (esp. when taking the esc and/or Motor and/or battery choice into consideration too) that almost every car will be a custom made thing with your choosen options, so there is a waiting time on those kits too (sorry but my day has only 24 hours too ;-) )

we do offer a wide body selection too, the newest body will be smaller to fit the small buggy chassis and could be ordered with a undertray soon.

the newest thing: 14,8 V lipo cells up to 48 A, 4000mAh, same size than 6x sub c, if 2 of these packs are used in my conversion kits, the driving time will explode : 8000 mAh at 14,8 V and at around 3,1 kg in the buggys !!!

hopefully these datas will answer some questions, if not : feel free to email me : constructor@ace-cars.de

greetings from hamburg !!

Re-Mix

12-04-2005, 11:24 AM

GriffinRU

12-04-2005, 11:47 AM

Hey, I just picked up an mbx pro to convert over to brushless with a 10L on 12 gp 3700 cells. What would reccomend as far as oil in the diffs? Also, will the speed compare to my lehner basic 4200 in the xxx-t on 6 cells?

10L and 12 gp3700 would be a little bit heavy and slow. 9L runs very good and cool. But when I put torsen center diff then 9L was replaced with 7XL.

While my friend runs 8L and 3S LiPo and that configuration is just pure fun to drive, fast and light.

Artur

P.S. 3000/torsen/1000 - front/center/rear

Re-Mix

12-12-2005, 04:56 PM

Thanks.

Also, has anyone run the plastic ofna gears with their buggies? Any luck? I've heard of a few who went through them kind of quickly. Not sure what the remedy would be, but the domintor slipper also could be a solution? Thanks

Muck

12-12-2005, 05:23 PM

tcolesen

12-12-2005, 06:39 PM

I run a plastic MGT spur on mine. I can't compare its strength to the Ofna gear, but it is plastic. So far, it has held up fine, but then again, it is mounted on a slipper clutch.

glassdoctor

12-12-2005, 11:18 PM

RRocket and I run Kyosho plastic gears. They hold up fine. If you do wear one out it's only $5.

tcolesen

01-07-2006, 11:47 AM

Is it me, or does it seem like the popularity of 1/8 electric buggies is dying down :confused:?

Anyways, my XTM X-Terminator is still running, and is always being modified. My latest change is a new chassis/motor mount to accomodate my LiFePO4 batteries. But, it won't be running for about 2 weeks. My servo fried because of the voltage regulator (external BEC) that later went up in smoke.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1684.jpg
This is an overall picture of the buggy. You can see the servo mounts (in front of motor), but with no servo.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1698.jpg
Here you can see all of the electronics (or would, if I had a servo). On top of the center slipper clutch support is a MGM Compro 12012 (yes, it did finally come back). I have it on 2 layers of foam and secured by rubber bands for a tight fit that will allow some movement in the event of a bad crash or hard landing. You can also see the motor, a Feigao 540C 9L. The mount for the motor is new, and mounts to the chassis using 3 screws, and is secured to the top plate using 2 screws. The front bearing support is screwed into the chassis with 2 screws, and also to the top plate with 2 screws. The rubber bands around it are for mounting an external BEC, and I will be getting this one: http://www.xushobby.com/servlet/Detail?no=38
Also visible is the receiver, which is mounted using velcro. To the left of the receiver is the antenna mount, and you can just barely see the white of the antenna tube.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1689.jpg
These "front" shocks replaced the older ones that didn't look as good and were broken. I say "front" because they are actually the shocks for the rear of the buggy (from when I bought it), but they give just as much travel as the stock front shocks. The reason why the preload is like that is because I am also using the stock front springs, which are (obviously) shorter than the rear springs. I need to get some stiffer springs for the front, though.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1693.jpg
A close-up of the battery mounting. Those velcro straps are custom made. The black piece that connects one of the straps was found on the ground, and since I didn't have another one, I made one from polycarbonate. You can also see the use of a foam pad, which is there to provide a small amount of shock absorbtion.
You can also see how I attached the front and rear chassis braces (the turnbuckle things) to the aluminum angle piece that is used for battery mounting.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1702.jpg
This is the (famous) LiFePO4 that I have been talking about for so long. It is comprised of 15 cells total (3.2v 1200mah), and there are 5 blocks of 3 cells in parallel (5 groups of 3.2v 3600mah) that are put into series (so 16v 3600mah total). This pack weighs about 150grams less than 12 NiMh cells, yet will perform like 14 NiMh cells or better. The construction of the pack has the nickel strips soldered together, and between each 3cell group there is a wire to give greater amp-handling capabilites (these wires are put on like they would be for a side by side NiMh pack). There are 2 sets of power leads coming from the pack because my charger (Duratrax ICE) can only charge up to 4s Li-Ion (this pack is being charged as Li-Ion), so I split it up into a 3s and a 2s. The whole pack is put into series by a series adpater.

http://img.photobucket.com/albums/v132/4x4pede/XTM%20X-Terminator/IMG_1706.jpg
And here is the battery mounted, snug as a bug in a rug :). The battery isn't going anywhere unless the battery straps decide to rip.

They say a picture is worth 1,000 words, and in this case that is true! Sorry for the lower-than-expected quality of the pictures, I couldn't get the lighting right.

The next things that I will do include:
-Put some sort of mud guard on the left (motor) side of the chassis to prevent crap from getting into the motor and receiver.
-Cut and drill holes in the chassis to remove weight.
-Get a new servo and UBEC.
-Get stiffer front springs.

Mr. Constructor

01-07-2006, 04:28 PM

I do have this buggy (the full XTM buggy line) converted soon too, the truggy will be ready within the next weeks, with a special drivetrain for monster truck gearing. ;-) these parts could then be ordered too.

And i´m working on a conversion kit for the Savage (6-24 cells, 1-3 gears)
and for you speedo freaks out there: a 8th scale picco/shepherd racing 4wd on road car is in the making too!!!
(with 12 cells AND 2 speed gear off course ;-) )

But anyway, aren´t there more buggys out there ???

tcolesen

01-07-2006, 05:23 PM

I read a few posts up that you were converting a XTM X-Terminator. The problem is, I can't gather together much money, so making parts is the easiest thing for me. My dad pays for the aluminum (I pay a little), and I have the necessary tools to make the parts. Mr. Constructor, I can guarantee you that if I had the money to buy your truggy conversion, I would! I even already have monster truck tires that I could use!

Muck

01-08-2006, 01:12 AM

I ran my Hyper 7 buggy today. It ran pretty good. The MGM 160 could be more smooth. I don't like how sometimes it slows down on you like it has a drag brake and other times it free wheels. I have the Mtronics truck ESC. I'm going to put in when I have time.

One problem I'm having with my Poly Quest 4s 4400, near the end of my pack it really heats up. It will go above 140 F. I have been stopping early to avoid this, but sometimes it's hit or miss. I'm guessing that I'm pulling too many amps for a single 4s pack. I'm using a 7XL and the MGM 160. I may have to rearrange my setup and use 2 4s packs?

I'm starting to like 1/8 buggy more than my 1/10 scale stuff. It seems to be much more durable. I always having to replace stuff on my rustler. I don't think the 1/8 scale conversions are dying down, It used to be uncharted territory and now it seems relatively easy to convert a buggy. I think it's that there are many more places to get the info than there used to be.

Tcolesen, glad to here you got your ESC back. Nothing like waiting for 1/2 a year for repairs.

Here are a few of pixs of my buggy with the dirt still on it.

Muck

01-08-2006, 01:18 AM

As you can see I mounted the MGM on its side.

Muck

01-08-2006, 01:24 AM

It's hard to get the pictures big enough!

Mr. Constructor

01-08-2006, 06:57 AM

As for the heat in your pack: the end voltage comes close, so the amp draw will arise a little too (as the watts that you "want" to have on the motor are the same than before when the pack was fresh)
this causes the pack to get a little into a higher inner resistance (due to heatup in general) and this also causes heat built up too, so it´s a circle, best way out:
use a LVC to be shure and on the safe side with the battery, there are a few out that slow down the esc if the battery is empty (these will function with ALL esc´s not only BL ones !!)

tcolesen

01-08-2006, 09:19 AM

Going along with what Mr. Constructor is saying, you may want to set your MGM to motor cutoff for the way the LVC will work. This will prevent overusage of the battery (even if it is over 3v/cell, it doesn't hurt to have it higher).

I remember Optimaman's graph of the Polyquest 2s 4400mah pack in his truck with the GTB and Feigao 380C 6t. It dropped its voltage pretty well! I am curious if your heat problem is of the same source as his low voltage.

Muck

01-08-2006, 09:51 PM

I think you guys are right about where my heat is coming from. The temps are fine till the very, very end of the pack. I'm not sure if I can change any thing on the MGM because I think the choices are 3s, 4s, 5s for cut off. Maybe I'm misunderstanding something though.
LVC maybe the way to go even after I switch to Mtronics, after reading about your tests tcolesen.

tcolesen

01-08-2006, 10:31 PM

One of the parameters for the MGM controller should be called "Behavior when accu
voltage going down", which means how the controller will cut off. The "Slow Reduce RPM" is a soft cutoff, "Motor cut off" cuts the motor when LVC is hit (what I use), and "RACE MODE" removes the cut-off (I believe).

Muck

01-08-2006, 10:43 PM

I think I'm set at "motor cut off" as well. I should check it though. It's obviously cutting out too low for these packs though.

tcolesen

01-09-2006, 08:40 AM

You would know if you have the motor cut off. The motor stops completely when LVC is hit, and only returning to neutral will allow you to apply throttle again.

Gojira

01-26-2006, 01:22 PM

what buggys have center diffs with plastic spur gears,please help

tcolesen

01-26-2006, 02:10 PM

The Ofna Ultra and MBX (not 9.5 MBX) series use a diff that works with the plastic spur. The Kyosho buggies should also be capable of using a plastic spur gear, from the Landmax or something like that.

Muck

01-26-2006, 02:46 PM

You could make an adapter or have an adapter made to fit the Ofna 51t spur onto certain diffs if not most. That is what I ended up doing.

Muck

01-26-2006, 03:01 PM

Here is a picture of my diff, adapter and spur.

xhumeka

02-11-2006, 02:10 PM

Hey guys!
Just got finished skimming through part I and II of these threads... GREAT material here!

Add my name to the growing list of those converting nitro to brushless, and I just need some advice.

I received an ofna mbx r2 (80 percent prebuilt) for my birthday, so I'm using that as my roller.

From everyone's experience, what is the MOST RELIABLE motor mount to use for the ofna chassis? Should I buy an emaxx motor mount and dremel it down, or are there better custom made motor mounts that are being sold by users of these forums?

I plan on using a feigao 9L, but I'm not sure about speed controller. I want to use between 12 and 14 cells, so any advice for speed controller is also appreciated.

Can't wait to get this thing going, but the first hurdle is the motor mount and I want to make sure to use the best option currently available.

Re-Mix

02-11-2006, 07:05 PM

Well, I ordered a coldfusion 6mm bent aluminum motor mount for my mbx pro, I'll let you know how that goes. The emaxx motor mount is a little too thin in my opinion, and will flex under the weight and ruin the gear mesh hurting the spur and motor. I'm also using a BK Warrior 9920, but an MGM 120 Compro, Quark Monster (expensive) could work well also. Have you thought about battery mounting yet?

xhumeka

02-11-2006, 07:11 PM

I've thought about battery mounting, but haven't decided on anything specific yet. I saw some posts about battery holders for pan cars, so I might give that a shot. How about you, have you found anything suitable yet?

I'd like something adjustable that will allow me to fit 6 or 7 cell SxS packs, so ideally it would be made of hard plastic for insulation purposes.

Muck

02-11-2006, 11:57 PM

AE battery cups might work for you. I mounted mine on a piece of lexan then mounted in mt buggy works well. By themself the the AE battery cups are a little flimsy but mounted on lexan they are perfect. http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LX2778&P=7

ScrubT

02-12-2006, 11:01 AM

I use kyosho twin force battery holders on my ride very stong and durable..

xhumeka

02-12-2006, 01:44 PM

two great suggestions, thanks guys. for my 6 cells i'd definitely use the kyosho holder, that thing looks perfect.

for adjustability, those AE cups are also perfect. thanks guys.

xhumeka

02-14-2006, 10:21 AM

hmmm, those kyosho twin force battery holders have proven difficult to find...

they USED to be on tower hobbies ( http://72.14.207.104/search?q=cache:DKV0KWDv5zsJ:www2.towerhobbies.com/cgi-bin/WTI0095P%3FFVSEARCH%3DMA109%26FVPROFIL%3D%2B%2B%26 search3%3DGo+%22Kyosho+Battery+Box+Set+Twin+Force% 22&hl=en&ct=clnk&cd=2 ) but it seems tower has quit stocking ALL twin force parts... not sure what's up with that.

The part number is MA109, but I can't find it anywhere... any suggestions?

Gojira

02-14-2006, 11:01 AM

tower quit selling all kyosho products about a year ago

tcolesen

02-14-2006, 08:59 PM

I've read that you can contact RC Monster Mike about these, and he should have them:
mike@rc-monster.com

mpetrich

02-14-2006, 11:15 PM

Hello,
I am in the process of converting a HB Lightning Pro 2 and from what I read here, I need to switch out the metal spur gear and use a composite. Does anyone know of an adapter that I can use or can you let me know the best way to switch out the metal spur?
Thanks for the help.
Matt

tcolesen

02-15-2006, 08:33 AM

Contact RC-Monster Mike (email link above), he may be able to help you out.

ScrubT

02-16-2006, 10:39 PM

Just go to your local hobby shop that carry kyosho items and order it. It should take about a week the LHS would order straight from Kyosho.. Why I guess great planes is not carrying kyosho products anymore..
That's what I did.. It should only cost $7 per tray..
hope this helps..

ScrubT

02-16-2006, 10:40 PM

Also I'm pretty sure Mike has them too. RC-Monster Mike..

Rotary Rocket

05-29-2006, 07:10 PM

Dusted off the rcs, charged up the LiPos and spent the long weekend runing brushless cars and trucks. Mostly the 1/8 K2 buggy.

This thing just flat hauls. The only problem is that it thermals after 10-12 minutes with the Hacker Comp controller. Got love the handling of a buggy.

Totally chewed up my derlin spur gear on the 1/5 BL rally car. The large scale is so much fun to watch. Nice four wheels drifts, etc.

I was thinking of converting a Landmax to BL also. Has anyone done one of these? The nice part is that it comes with a nylon spur. I was thinking of moving the center diff up but put the motor next to it. Almost the opposite of a TC3. Still put the batts close to the center and in the back. Just like my K2 convertion. Them mover the steering servo to the opoosite side. This should net the lowest center of gravity while keeping the weight as centered as posible.

I'll post pics to this thread as I start...

Cheers.

GCMustang

09-14-2006, 05:24 PM

Interesting that you're thinking about converting a Kyosho Landmax because I'm thinking about converting my Kyosho Inferno GT after seeing the Fine Design conversion. It's my first nitro, and I'm really not that impressed with it. The speed and acceleration is ok, but it's just not worth the hassle of tuning the carb, fretting over 300F+ temps, going through glow plugs, etc.

That said - it looks like you guys are dealing with some serious temp issues. What controller/motor combo would you guys recommend for spirited bashing (no racing) that would run cool and reliable? Would the Mamba Max controller be adequate?

glassdoctor

09-14-2006, 07:52 PM

With a Neu motor I would say yes.... I have bashed mine in the street hard and the MM stayed cool as esc temps go. Not even close to thermalling....

Other motors may be more of a problem, I don't know.

tcolesen

09-14-2006, 10:29 PM

Soon I should be able to do some testing with an 8L on a Mamba Max (Saturday/Sunday). The batteries used will be 4s 6300mah 15C, and I think the gearing will be a bit high. This setup should work the Mamba Max pretty hard. I'll make sure to check temps, and I can even use the Eagle Tree MicroPower to see how much current the motor will be using.

GCMustang

09-15-2006, 07:33 AM

The MM isn't supposed to see more than 3s as far as lipo's go, right? I'm definitely curious to see how your test goes, tcoleson.
The motor I really think I'd like to use is the 10L.

For batteries, I was thinking of buying a pair of Maxamps 2S 4000mah 7.4V packs, allowing me to use them in parallel for longer run times and more current capacity, or run them in series for the occasional insane speed run to wow friends. Anybody tried this?
I'd also be able to use the 2S 4AH packs in my 10th scale touring cars, is part of the reason I wanted to go that route.

tcolesen

09-15-2006, 08:58 AM

It can do up to 14 cells, as long as the BEC is disabled and a separate power source is used for the RX. I've been using the Mamba Max this way with 4s Lipo for quite a while now, and so have several other members (like glassdoctor).

jamesbernatchez

09-15-2006, 12:28 PM

Finally, I decided to get some photos. I have run into a few problems to get this far.

Setup completed I ran the buggy a few times with BEC on. The buggy cogged pretty bad, really bad, but since I have nothing to base it on I don't really know how I should describe it. A few runs later, I decided to get a use from a reciever battery still packaged laying around for a year. I ran a run or two normal, then after the cycled batteries were done I threw them in. I took out the BEC black jumper off to use the receiver pack. A minute into the run and the car just died. Nothing, not even the steering servo. I took the receiver off and put the receiver pack in and a servo to test it and nothing. Which was very wierd. I tested it out with another receiver and nothing again. I had no idea what it was. I then put the jumper back in and plugged the receiver pack in. I reprogrammed it and it started working again. I hope its not bad to use both, but I finished off the maxx paxx with it setup that way, it had to have run more than 4 minutes not including the previous minute. I used my other packs and its still fine, no official time yet. It still cogs starting under 1/4 throttle, but smoothly runs at a slow walking pace. Motor got warm, ESC got warmer, and the batteries get pretty hot. Nothing horrible though.

But anyway, the car rips. The 9L is almost too much. I would not reccomend anything under the 9 for buggy purposes if bashing also includes racing. If you bash, I don't care if you go for the 7, but you might not like the runtimes. I'll get some official times tomarrow if nothing more goes wrong.

Combat....is that an emaxx motor mount? Can you take a few good pics of it so I can see how you have it mounted/cut?

That is what ill be using in my LSPR w/ NEU 1515, Quark 125 Monster Pro, Maxamps 8000mah Lipo. Here are a few pics of how it sits now. Im waiting for the emaxx mounts and then i need to order the motor and esc :) The brakes will be coming off and the radio tray is cut to just hold the steering servo.

http://i78.photobucket.com/albums/j98/jamesbernatchez/HB%20LSP-R/DSCN2924.jpg
http://i78.photobucket.com/albums/j98/jamesbernatchez/LSP4.jpg
http://i78.photobucket.com/albums/j98/jamesbernatchez/LSP3.jpg
http://i78.photobucket.com/albums/j98/jamesbernatchez/LSP.jpg
http://i78.photobucket.com/albums/j98/jamesbernatchez/LSP2.jpg

And my new radio ill be controlling the LSPR with :D Oh and with Spektrum PRO setup

http://i78.photobucket.com/albums/j98/jamesbernatchez/AirtronicsM11.jpg