The "Raven"

[Rockit]

first off im not really a rc enthusiast.. im just building a RC plane becasue its something to do...
could someone please tell me where the center of gravity of the plane should be as an approximation...
also i dont know much about what size engine to buy/ what transmitter to purchase etc.. so if anyone could give me some pointers then that would be good.. i dont want to spend a heap of money.. but i also dont want to skimp on quality...

ive attached some concept images of the "Raven"
thanks

[Rockit]

and another image

[Rockit]

and another

[miraclesailor]

It would help if you gave some more information. To figure out what motor to start with it is nice to know what the weight and wing area of the plane is. If you want to get a starting point yourself you can look at some other planes that are close to what you have and start from there.

As far as CG you could start with 1/3 the way back from the leading edge of the wing. Find a nice place for a slow speed crash and toss it level with all controls at neutral. Could try the slightest amount of up elevator, if you like. Plan to toss the plane about 12 to 15 feet straight ahead and not more than about 5 feet off the ground. Do not toss it up at all but level with the ground. That will give you a good idea about how close you are to trim.

Later,
Dan

[Rockit]

wingspan is (at the moment, may change as i actually build the thing and experiment with it) 46" from wing tip to wing tip
length is 36" from nose to rearmost point..
wing length is approx 18" each and wing width is 5" (im not sure of this should be thinner) wing height im still deciding on ( any ideas?)

weight is currenty unknown but im building it out of fairly lightweight materials so it should be fairly light... ill get a better approximation of this later next week when construction begins (hopefully)

thanks, any imput would be greatly appreciated.

[NitroDad]

Thats a nice lookin plane, I will be interestead in how it flies.

[BROKENARROW]

first off im not really a rc enthusiast.. im just building a RC plane becasue its something to do...
could someone please tell me where the center of gravity of the plane should be as an approximation...
also i dont know much about what size engine to buy/ what transmitter to purchase etc.. so if anyone could give me some pointers then that would be good.. i dont want to spend a heap of money.. but i also dont want to skimp on quality...

ive attached some concept images of the "Raven"
thanks



As a rule, your C/G is about 1/3 away from the leading edge. However, in your case, the only thing left after that is a LONG boom and the obligatory rudder & horz stab. Not much weight there. We all can only take an educated guess and move it a little farther to the front - in small increments.

Make yourself a small jig that will allow you to balance the plane when it is all finished. Take 4 --- 1/2" hardwood dowel rods cut about 12" long. Connect the two together in parallel - flat on the work top. (far enough apart to accommodate the width of the FUSELAGE).

Take two long pencils (no point) and drill a hole in the top of the assembly. (both sides) Make sure that the rubber erasers place under the bottom of your wing. Balance your plane with and without a full tank of fuel. ("YOU WILL FIND A DIFFERENCE") Aim towards the empty tank. This way you should still have control when you're getting down.

I hope this helps you a little.

BROKENARROW

[Rockit]

thanks..that helps a lot...
construction has effectivly stopped now untill my next big holiday. because im back at uni now and dont hav much free time...but im plannign on finishing it in the next possible time..

[carmatic]

just out of curiosity, how do you plan to get your building materials into that shape? lasers or something?

[BROKENARROW]

Carmatic

Balsa Wood of Foam wold be the best bet

Take a look at the unit, The rounded canopy can be a very generic clear plastic that can be purchased from a variety of sources. The long boom arms are nothing more than a pair of hardwood dowel rods. The wings and canard area are a standard fabrication of ribs and cross members along with an up/down control surface of some type. As far as the little virtical winglets at the wing tips are concerned, I leave those off till after a few flights. IF you need them to help stabilize slow flight then I feel they should go on with a +2-3? installation. As far as the shaped area between the canopy and in front of the PUSHER PROP, a small amount of solid balsa will suffice. Simply sand it to shape.

I hope that answers your question

BROKENARROW

[carmatic]

ah yes, i have a similar thing going on where i sand something into shape... but its a plastic part on a hovercraft , just grind away with a file, should look much better than the computer generated model when its done properly

didnt know what 'canard area' was, looked it up in google, and stumbled across http://www.casde.iitb.ac.in/we-also/des-comp/md-sathak/pages/material.htm , turns out it can be quite similar to what the thread starter was trying to do , like using balsa wood and aluminium... its a model of the wright flyer

[NitroDad]

Are you up and going yet?

[Rockit]

finally, after much procrastination and laziness this plane is actually getting somewhere!! the design of the (very) front section has changed slightly, as i accidentaly bought a fuel tank that was too big for the old design, will give it a test run if doesnt perform well will buy smaller tank and remake that section.


completed:

wings are completed, just have final touch ups and paint.
Body 50% completed,made out of a solid lump of foam carved to shape, will coat in carbon fiber after its shape is perfected.
engine purchased and mounted
fuel tank installed
radio equiptment installed and working
servos bought, just waiting for them to arrive so i can install them


still on to-do list:

tail section needs to be made, and also small 'winglets' at front also need to be made.
attach control surfaces to wings.
appart from that is all good!!!



ill post pictures as soon as my brother lends me his digi camera!
hoping to have it completed in the next 3 weeks so i can take it to the skies in my holidays. (oh dear.. god help everyone near where ill be flying it)