I need some help with wingeron design for something light and small. My best source has been a slope sailplane or two.
This has troubled me for sometime as what I am proposing is not of high performance. What has inspired me has been the french Pou Du Ciel plane which has an articulated main wing to control incedence instead of using an elevator for control. Also an early biplane (Lougheed S-1) by what would be known as Lockheed used the lower wings for aileron control and both entire lower wing panels could also be swung in unison up to 90 degrees to be used as an air brake upon landing! After flying this same plane could fold its wings back for storage having the lower panels in a verticle position against the sides of the fuselage.

I wish to try and combine both incedence (easy stuff for a parasol arrangement) and wingeron function.

This should not be terribly difficult using two servos and flaperon mixing. A little more difficult if your radio does not mix for you.

My biggest hurdle is weight and then materials. The model I want to build is a small electric park flyer where having light weight is paramount.

As to materials, I want to use must be as commonplace and simple as possible.

I have already figured out how to make the wing removable for parasol and wings attached to the fuse.

What I don't know are possible tubing (or tubing/rod) choices that nest well, one inside. Also could this be done without bearings? If not, small bearings will need to be employed, of which I have very little knowedge.

The model I propose will be a light weight, slow parkflyer to start with and have between one inch to one and a half inch width inside. Foam or balsa for constuction. This will need possibly metal plates or plywood to help with the load bearing in the area. This will need to be very thin or have lightening holes to help dispence weight.

I want the all up weight of the model to be under 10 ounces preferably.

Any ideas?

Robert

Carbon fiber tubes should work for tubes and wooden framework for the fuse. would be ok for the bearing surface.

No need for classic "bearings" but you will need to allow for some flex in the system or it'll bind. For the pivot rod in this case I'd suggest a length of something like 1/4 OD carbon tube that has a nice slick outside finish. Then pass it through the wing ribs at a chord point that puts 25% of the wing area ahead of the hinge line. The root rib should be made from 1/16 plywood and at a point out near the end of the pivot tube the rib there should be also made from 1/16 plywood as well. Accurately mark and drill the holes for the pivot but go for 1/32 oversize. Then glue in short sections about 1/4 inch long of 1/4 ID aluminium tubing. Any ribs located between these two bearing ribs should be drilled with the same oversize drill or punched out using sharpened brass tubing to the same oversize fit. The only two spots you want touching are the short bearing tube segments. A thin wipe of the carbon rod with some sort of lube will be all you need for a nice fit and operation.

To hold the wings on you'll need some sort of pin that inserts through the wing and into the tube to retain the wing from sliding off.

Why only touch in two spots? The carbon pivot tube is going to flex. When it does you don't want it to try to flex inside a rigid tube. By only supporting it at two points it is free to flex without binding. The tubes will have enough play to still operate freely despite the slight flexing of the carbon tube.

At least that's how I'd do it for this sort of scale...

Actually Quarter inch sounds a little big even for the size I suggest but then this is why I am asking here. I don't want to fail first time out. With more Good info like this, I will lessen my chances of failure at all.

As to the flexing between supporting ribs, I thank you dearly for this info as I would not have thought of that aspect myself.

Quarter inch would certainly be more safe than anything smaller (as I was thinking would be appropriate) !

Robert

What wingspan and cord size are you thinking? I know you are looking at 10 oz as your total weight it would be easier if we had an idea of actual size

I'm glad you asked! I do not have a specific design in mind as this gadgetrywould adapt itself to a number of designs of which I plan on trying several.

The testbed will be a shoulder wing model with a span of 38" and chord of 7". The airfoil will be undercambered and four percent of the chord. Fuse length will be 27 " A floater if you will. The wing will have a flat center with the end panels in dihedral. \________/. This is of course an exaggeration of the dihedral!

Thanks for your input !

Robert

Four percent of cord for your airfoil makes for a very thin wing, sounds like something about the same as a great planes flat out. I had one of those and there was a lot of flex to the wings, as a matter of fact I would get them to flutter at top speed with a brushless motor.
I would suggest that you make a tapered wing, starting with the foil a 8% at the root tapered down to 4% at the tip. That would allow for your rod to be large enough to carry the loads at the root and the wing will still be thin enough to reduce overall drag. Or you could try it with a smaller diameter rod setup and see what happens although I have a gut feeling that you might have a problem with flex or flutter. If the plane is light enough that may not be an issue carbon fiber is very strong for its weight but I have never tried anything as small as you are talking with it. There are sizes as small as 1/32 diameter you can work with although they are not all that rigid and bend quite a bit. Go to the hobby shop and take a look at what they have, try to flex a piece that is around the size you want to use at the length you need and see how it works.
Good luck with your design...
I am working on a plane right now that has the type of wing you described built by a fellow club member, I picked up at an auction.

For a 38 inch span electric model I'm going to guess at around a 12 to 16 oz weight depending on a lot of factors. At that weight I'd still be recomending a 1/4 inch tube to avoid too much flexing during any higher G pullouts. Just go with a thin wall for lighter weight. I've got a length of 3/16 thin walled carbon tube and it's pretty flexy. More flexy than I'd want for this size. Perhaps for something around 24 inch span it would be OK. For a 36 to 40 inch model I'd be using 1/4 tubing with a .035 to .045 wall.

Also even for undercambers 4% is REALLY thin. Most of my free flight stuff is closer to 6 to 8% depending on the airfoil.

With undercambered airfoils operating at lower airspeeds near the stall you'll need to worry a LOT about adverse yaw. And it's not possible to use differential throw in a wingeron setup to avoid this. The trick, if you go ahead with it, will be to use VERY small roll control inputs when flying closer to the stall speeds and rudder only when in the final flare or at speeds right at the stall speed.