Help with electric conversion

[losiXXXman]

I bought a House of Balsa Schoolyard scale Super Decathalon about two years ago. The kit calls for a .061 ti .12, but I want to run electric. Guys at the LHS rccomended a Mod motor in the range of 17 turns direct drive, whoch is what I wanted to run since I had it laying around. Will this be a good match? If so how many and what mAh cells should I run? I want flight times greater than 5 minutes but they need not be much longer. Not interested in dealing with Li Poly Batts. Nicd or NiMH only. Would also consider speed 400 motor as well, but wnat to stick with direct drive to save weight of a gearbox. Anybody got any suggestions?

Also - I'm not aiming to get aerobatic right away so a slower flight speed would be good as well...

Wing span 47 in.
Fuselage length 29 in.
Wing area 329 sq. in.
Wt. with radio 24 oz.
Wing loading 10.5 oz./sq. ft. Info from HOB website.

[miraclesailor]

Losi:

Seems that a Speed 400 with a direct drive Gunther 5.25X5.25 prop should work well. You would ideally put at least 8 cell NiMh of 1Amp (AA or A) or more for a flight the length you would like. This will be a bit of weight but it will fly okay. If you would like to compare that with a Brushless you could use an Astroflight 20. It would give you more umph, but you do not need it for this plane.

Later,
Dan

[losiXXXman]

First of all, thanks for your help. I've been into cars fo like 12 years, but the electric systems that planes utilize is so much different, especially when you get into brushless. This setup sounds great, and economical too. 400 motors are $10, and a controller for that is only 25. With a Battery at 20-25, I'm not looking at too much outlay.

I don't know where to source Gunther products. Can you tell me where? Else some other props that would get me airborne. Also will this plane ROG or need a hand toss? Ideally I'd like to be able to ROG, although that may take a different propulsion system later on.

By the way, do you sail also? My father in law got me a TT Victoria for Christmas this year. I cannot wait ti start building it...

Wes

[miraclesailor]

Losi:

The Gunther prop is the same one the would come with an electric combat wing like the Zagi. It is a push on prop that usually stays on pretty well. I have not been to a hobby store that does not carry one, but they may not call it a Gunther prop. Look for a simple push on prop that would fit snug on the shaft of the 400 motor. I think at the weight you are talking about you should have no problem ROGing the plane.

If you decide to jump to the brushless "oouhhh?" (read as Tim Allen would say). There would be some bucks to put out, but oh what a feeling! The AXI motor about $75, Castle Pheonix ESC $55, batteries to handle it. This is hardly neccesary right now, but will be something that you covet in the future.

I race Catamarans, Formula 18's. They are the latest HOT thing. Trapezing both upwind and downwind. Very Fast!!! :eek: I have been racing catamarans for about 28 years.

I have sailed RC boats but never owned one. I have thought about designing and making a 1 meter but there is not enough time...life is very busy.

Later,
Dan

Later,
Dan

[losiXXXman]

Dan,

Well your sailing experience outweighs my life experience!! I'm Jealous. Anyway, I have become interested in sailing in the last year or so, both RC as well as REAL sailing. I have yet to even be on the water, but hope to lern next summer in a sunfish at the local lake. Of course, I'm getting a Thunder Tiger Victoria RC yacht for Christmas so the fundamentals will be known to me then. It would be a dream of mine to do some bluewater sailing, allthough I don't think I'll ever have the money for that...

As for the plane, do you think that I could get it in the air on a 540 motor and 6-8 subC cells. I have some old 1700mAh laying around, as well as 540 and even modified car motors. I have an APC 9x7? I believe. I don't have a scale so I cannot even estimate how much weight this would be. What do you think??

[aeajr]

I don't know this plane you describe. Can you provide weight, wing span, construction, or can you provide a link to a web site that has them?

If it is under 8 ounces empty with a wing span of 36 inches or more, a speed 400 direct drive would be fine. Typically you would want a 900 mah 2/3 or 4/5 A type battery in the NIMH family. Something from the Hobbyzone family, 7 cell, would probably do very nicely. They weigh about 6 ounces. Add 2 micro seros and a speed control and you add another 1 to 1.5 oz and you are all up weight is under 16 ozs. The motor will pull about 8 amps.

As for gearboxes. The weight of a light weight parkflyer gear box is not an issue as it allows that speed 300 or 400 to turn a bigger prop. Something like a GWS 350C-C or 350-D motor/gearbox would be appropriate:

http://www.gws.com.tw/english/product/powersystem/eps350c.htm

or

GWS 400C motor/gearbox
http://www.gws.com.tw/english/product/powersystem/eps400c.htm

They come as a package, typically in the $20 range.

EP8040 8.4 6.5 327 11.45 54.60 5.99 210

[flyinhigh]

Todds models should have the Gunther prop you are looking for.
Id try that for the cheapest setup for now.the NiCad's will weigh you down but if its all you got then what can you do..

Like aeajr said the 350C would give you more then enough for this plane..Im using a 400 with a 5x5 on my lil AT-6 pylon racer.. probably more prop speed then you need but should work ok ....

Waite a min I didnt see you at 24+ounces... DD 400 no good.

[flyinhigh]

Here is a link to the plane http://www.houseofbalsa.com/e/env/0001ZTiBhnWB1QcsdQ2P2D4/store/store-kits.html?link=/store/store-type-tem.html&item=products:k-21

your not going to come out much lighter then the IC version without LiPo's You need to look for something with 50% thrust ..So your plane weighs 26 ounces look for a unit that will put out 13 ounces of thrust.The Gws 350 series are perfect.You can downgrade your batteries to a cheap 600 NiCd pack then and bring some more weight off. although youll have short flights.
If you can get your planes empty fuse weight it would be much more helpful..
There is alot more to converting a plane then this.getting the over built fuse lightened is another thing to look at...

[losiXXXman]

flyin,

Well, I guess I'll go with a SP400 and some 1100 NiMH A cells. I refuse to buy another charger specifically for LiPro. I'm spread so thin, with RC cars, planes, and boats. I don't know if the plane can be built much lighter. I could swiss cheese the fuse, but I'm reluctant to due so, because I want to have some crashworthiness. I'm getting ready to cover now, so it would be the time to do so (cutting up) but I want a strong structure.

PS the whole reason I've refocused my RC exploits on boats and planes is the improvisation. Working with balsa and foam for planes, and boat guys seem to really scrape around for materials for masts/ booms, and other stuff .... Seems like my limited budget will go farther. Racing RC cars is so high dollar, and people always give you funny looks if you "homemake" parts for your car...

Sorry to rant.. If I get the plane together before I buy a 400 and a battery pack, I'm going to give the 540 and 1700's a go...Wish me luck she'll be heavy !!

[flyinhigh]

Hey Good Luck!! Hope all works out..a stock 540 will probably be better then the 400..or even a 550 if you can get it.