Glider Wing - FT / Nerd Nic Crossover

[xMeox]

Hi there,
I finally got my foam board from oversea and Im really pleased with it! It is so much lighter and easier to handle than our foam board in europa!

Anyway, Im building a tiny trainer atm, but Im not very pleased with the 3 chanal wing. Dont get me wrong, the design is awesome in terms of simplicity of the build and strength, but I think there are several options to improve the glide ability of it.

The first thing Im trying to do is to get the rear edge of the wing as thin as possible, similar to Nerd Nics builds. The middle part of the wing needs reinforcement, otherwise the rubber bands will just cut through it, but other than that it should be easily doable. IMO, this should boost the wing performance a lot!

The second thing I want to try is to remove the inner, upper layer of paper of the wing. It will become lighter, and a smooth round upper side, instead of the two hard edges on top of the wing. Im not sure if this is a big boost in performance and I guess people havnt done this because it will highly affect the durability of the wing. But as Im trying to design a pure glider this should be no big deal.

When the design works out well, Im going to map it to the Simple Soarer, which will require some reinforcements I guess.

If anyone has tried something like that and has some input for me, I would really appreciate it

best regards,
xMeox

 

[TEAJR66]

Check out the way Ed from experimental airlines builds his Armin Wings. They are very slippery compared to the three break wing. You will get the same speed envelope of an FT Style wing of the same chord, just a little less drag. Powering off won't feel like hitting the brakes.

My first DTFB plane was a Simple Soarer wing on a scratch tube fuselage. When I swapped over to the Armin wing on the same plane, it had a much nicer glide tendency.

https://www.youtube.com/watch?v=qJZoqGHAIDE

There are several in his series. This one will get you to his channel.

 

[wilmracer]

So I'm building one of NN's designs at the moment and I have a thought in this. I'm building with model airplane foam that does NOT have paper on it. I haven't done it yet but it would be easy to lightly sand off the ridges at the bends to make the wing a bit smoother while keeping the airfoil shape right. Not sure how much of a difference it would make but it wouldn't hurt.

 

[Spastickitten]

I made a maker trainer, and the leading edge is sanded to a point. I would think that tapering the the leading and trailing edge like Nerd Nic would be interesting, but not needed

 

[Tench745]

I've done a lot of reading on foil shapes, not for airplanes but for sailboats. The principles are the same in many respects. One of the things many people do wrong when crafting foils for boats is tapering the trailing edge to a razor point. This is detrimental for two reasons. 1) The airflow stays attached as it leaves the foil, making flutter much more likely. The air needs a little space and a sharp (not rounded) edge to break off from the surface. 2)It's hard to keep a razor edge from becoming dented/nicked.
I think the FT 3-fold wing shape, when used on a thin wing has little detriment over a curved wing. As the foil becomes thicker for the same chord the angles become sharper and drag increases into the range where you notice a difference. I removed the paper from the inner surface of my blunt-nose versa to give it a smoother curve. With the outside taped durability has not suffered, and it looks so good.
My recommendation when tapering the TE would be to leave it about 1/16" thick and remove the paper from the wing's inner surface for weight more than for the aerodynamics/beauty of a curved wing.
My 2cents.

 

[xMeox]

Thank you for the input guys!
So in conclusion the front edge should be thin for speed but have a nice (round) airfoil for gliding.
Removing the inner paper gives a lighter and more beautifull plane.

The rear edge should be thin for both gliding and speed wings, right?

Thanks for the link, im going to check it out and try to merge the ideas into my wing.

 

[xMeox]

Quick update:
I started to change the FT planes and sketeched and build several versions of a mixture between flitetest and armin design. I did one armin wing following the steps of the tutorial video, just to be able to compare the two build processes and my conclusion is that both variants have pros and cons.

The thing that bugged me during the armin wing construction was the rear edge modification after the wing was folded and glued. In the next version Ill sketch up plans and do the edge modification before folding, well see how this will turn out.

For now, I got an armin wing with dihedral and wing tips (FT style). In the next iteration, Ill try to build some nice wing tips, something like the one nerd nics uses.

I hope the weather will be good tomorrow, really looking forward to compare those wings

 

[xMeox]

Well, the latest version of my wing is ready (at least one half), and it looks very promising!
To be able to compare my wing to the tiny trainer sport wing, I kept the size and the thickness of the wing nearly the same. Later on the profile might get thicker to get better performance in gliding.

My steps so far:

I started with the FT Plans of the Sport Wing. Instead of gluing the spars to the top of the wing,I glued them to the bottom, because I remove the paper of the upper wing side late on. I changed the form of the wing tips and extended the bottom side of the wing so the wing tips and the rear end of the wing also have a downer side of foam.
Before I flattened out the foam to the wing edges, I cut the edges to where the bevel should go, as nerd nic does in his builds (I also use this to get the 45° angle in the middle fold of the wing. Just remove 0.5cm of paper to the left and right of the main cut and use a knife to remove the foam.)



Beveling the edges where a big pain in the a** the last few tries. Now I figured out how to do it with my setup. Instead of clamping stuf together (armin wing construction) or going with a few cuts (nerd nic) I did everything in one cut. Instead of placing the wing near to the edge of my cutting map, I put it behind more than 2 cm. This worked out great with my setup. I guess this strongly depends on the knife you use, If mine would bend less, I would not need this much distance..



I kept the basic spar form as in the FT plans, but I removed 2/3 of the paper of the outer spar (1cm on the front and 1cm on the back) so I can get a better airfoil.



I didnt glued the wing yet, because I want to join the two wing halfs together first but I havnt started the second half yet. But the airfoil I got looks really amazing and better than anything I built so far.



Im really looking forward to compare the three wings (FT, armin wing, own design) in flight,

 

[nerdnic]

Now that's a pretty wing!

 

[xMeox]

Thanks for the comment and your inspiration!

Finished the wing today.
I hope I can test fly tomorrow.





Im very pleased in the end result, though for the look it might be better to use tape ad the wing tips and edges after gluing.

This kind of wing opens a new door for me. Got some nice ideas in my head

 

[xMeox]

After several flights in different wind conditions I can finally give some feedback on this wing.

First of all, did I accomplished all my goals with this design? To be honest, no i did not.

The version above (similar to the FT Tiny Trainer Sport Wing) has awesome flying characteristics. Its a little bit faster and due to flattened wing tips it does not stabilize a lot, which is nice in sport flying. The drag of this wing is noticeable smaller, though it does not produce much more lift than the original one.

The version with two layers of foam as wing spare does produce too much drag. It is simply to think for this little wing. It is a really nice slow flyer, but again, not a good glider wing.

I guess that the advantage of such a wing will pay of more if the wing is bigger, there for the next project will be a FT Simply Soarer with an wing similar to the one above

thanks for all the tips and inspiration,
xMeox