Designing and Building Model Airplane Wings
 

Does anyone here have experience designing and building custom/original airfoils for model airplanes? I've built hand-launched balsa models from a kit, but never a large scale (wingspan will be around the 6' size-range) original design for a controlled airplane.

A semester long class project has us designing, fabricating, and flying an electric RC model airplane of original design. My main responsibility in the assignment is for the wing design.

To keep things simple (as another team is responsible for the actual construction of the aircraft), I'm working up plans for a straight hershey bar wing (think Piper Cherokee) with a nearly flat bottom and a fairly thick wing to give better slow flight characteristics and stability. Also planning on high-wing configuration with some dihedral.

My snag at the moment is in figuring out what the order of operations should be in terms of deciding on aspect ratio, intended wing-loading, and specific wing span. In other words, I can't plan my wingspan or aspect ratio until I know what kind of wing-loading I need to plan for, right? (Preferably a lower wing-loading).

I'm being provided a fuselage, batteries/servos, and engine, and am waiting on exact numbers for what the total weight is of these bits.

Any modelers here have any tips or advice? Does my initial wing setup sound functional? :)

Old thread... so how did it come out?

I have never done this hobby but I think when I finally do, I will come up with a design in X-Plane's PlaneBuilder before making anything in the workshop. X-Plane P/B lets you see how something is going to fly and all the basic aspects are there from airfoils to wings to propulsion and stability and control. It's fairly crude for sure, but you can design something and see if it flies with reasonable fidelity in the simulator and get a feeling for what works and what doesn't. You can also build remote control flying skills which will be pretty handy when you actually have a model. To do that, set the simulator to chase view and distance yourself from the model using the "-" and "+" keys. Then you can build the model airplane and verify that it works. The comparison should be pretty interesting.

The airplane actually flew pretty well. We over estimated the power required and so our chosen motor got the airplane flying within about 10 feet or so. Way too much power but it was fun to watch the airplane rip it self off the ground.

Its been too long for me to remember now, but the airfoil design was based off of one of the tried and true NACA designs. We had a small wind tunnel and tested a section of the wing in it; sure enough, it worked.

The best part was when the pilot lost the plane in the sun after about 5 minutes of successful flight and stalled it. When the plane came back in sight it was in a vertical dive that was probably recoverable, but he hesitated and for some reason ended up attempting an inverted negative g recovery. The wings ripped off and the whole bit splashed into the dirt. Some people were disappointed, but I thought it was awesome. :cool:

Did you use a fully symmetrical design? With the models they are remarkably forgiving -- I used to build some that I thought would *not* fly but they would get up and be pretty ok - any "teardrop" shape will have adequate flight properties... may not be great, but always adequate. Wish I had a wind tunnel - that sounds like fun!