Hatty

OK. I want to design and build my own plane. I am going to use the s1223 airfoil and it will have to lift a reasonable amount of weight given it is an electric. It will be rudder/elevator/throttle controlled. But I have a few questions.

1. I was thinking about making it a biplane. How difficult is a biplane design to integrate into a fuselage? Are biplanes harder to control than a monoplane?

2. How large to the control surfaced have to be for a stable flight?

3. Where does the center of gravity need to be with the s1223 airfoil?

I also was wondering if you could post pictures of your electric 3-channel plane.

Anyhting else you want to add, then go ahead. [8D]

MinnFlyer

My Feedback: (4)

I would strongy recommend that you buy a simple kit first. There are many aspects to building that a kit will help you to realize. You wouldn't want to go through all of the trouble of building a plane just to have the wings fold up on the first flight, would you?

Hatty

Well I have designed and built rubber band airplanes befre that carry a rediculour amount of weight. I do have some experience.

FLYBOY

My Feedback: (11)

There are a ton of ways to mount the upper wing, but I would suggest you design the first one as a monoplane for simplicity and see how it goes, then work toward a bipe. There are more problems when you add the second wing that could really screw you up. I would start with a high wing design if your heart is set on scratch building. I have a friend doing the same thing. I can't get him to do a kit, and he has built a few from scratch. He built a kit a while back and I think it helped him see some different techniques he needed to learn. Kits help on that respect. If you just start out scratching, you have to develope ways to overcome problems that are already developed. You just won't know how to do it.

If you have to do it, keep it as simple as possible, do a search on google for formulas for figuring sizes of tail surfaces and wings, and CG. There is a lot more to it than just slapping a wing on a stick and flying it. You need to do a lot of research on it before you start, but it is possible and fun.

Have a good time with it, thats the important part.

DBCherry

My Feedback: (4)

There are things to consider like tail moment, and wing and stab incidences, and figuring the CG would requiring figuring out the MAC (Mean Aerodynamic Chord) or the wing. The entire wing's planform has to be considered, so no one can tell you what the CG should be.

Generally speaking, I'd suggest ailerons, elevator and throttle, but if you're set on rudder, then make sure you also design in at least 3 inches of dihedral to keep it stable. I'd also suggest that you plan on about 40% of the vertical stab for the rudder, and perhaps 20 to 30% for the elevator. (If going with ailerons 20% of the wing should be fine.)

I'm sure some will disagree with these numbers, becasue a lot depends on the aircraft design and your preference for control sensitivity.

Here's a diagram that should help you determine the MAC, and the CG of whatever wing you design.

Good luck, have fun, and welcome to RCU!
Dennis-