Solved FTFC20 Design Challenge Draft Idea Thread

[willsonman]

Let’s talk washout.

Seems to be pretty common in the designs I’m looking at (“might” rhyme with Sweet Pea)....

So, I’m not sure there’s an easy way to do that in foamboard. One option I saw was simply build it with each (both) ailerons a tad up (above the wings surface.)

I also wonder if this is why we see undercambered wings on most FT designs?

Thoughts/comments?

Additional thoughts:
Washout also relates to adverse yaw. While the FT undercamber approach does prevent the "tip stall" issues similarly to washout, it does not address adverse yaw associated with this approach. Generally, FT overcomes this by having and increase in vertical tail area. Overall these are inefficient approaches because if the increase in drag they inherit. Proper washout will have the best of both worlds without needing to increase the vertical tail area. The advantage in a model is that you have a much longer glide path when unpowered and you have less of the typical FT "plop" landings.

 

[rockyboy]

Additional thoughts:
Washout also relates to adverse yaw. While the FT undercamber approach does prevent the "tip stall" issues similarly to washout, it does not address adverse yaw associated with this approach. Generally, FT overcomes this by having and increase in vertical tail area. Overall these are inefficient approaches because if the increase in drag they inherit. Proper washout will have the best of both worlds without needing to increase the vertical tail area. The advantage in a model is that you have a much longer glide path when unpowered and you have less of the typical FT "plop" landings.

Good points! Maybe this contest will be the trigger for people coming up with good, repeatable ways of building washout into foam board wings!

 

[Vimana89]

I'll update my Floating Kobra/Kidney thread with the prototype progress, and draw up some quick sketches of a more refined version with a full box fuselage. I am really enjoying flying the prototype, but the wind picked up to critical for the day. I'm at page 135ish of 180 on Outerzone. It seems these are the "newest" submissions with hundreds more in the archive...that's really something. I'll be launching into more prototypes before you know it.

Here are two I'll be taking a crack at next.

The Mooncrest. Cool look and design, I can do a well protected prop with a no-brainer thrust angle. I will be ditching the profile piece for a an A fold box fuselage, even on the prototype. Multi-wing is a new ballgame for me besides in a sim. This will be my first bipe. Standard and friendly RET controls.


This next one is a great replacement for the Last Laugh I wanted to do originally. Called the "Pixie", this little slender delta will help me finally learn to get elevons right. It has the weirdest under-hanging canard, that looks cool, but I'm interested to see how the handling is.

 

[kilroy07]

Additional thoughts:
Washout also relates to adverse yaw. While the FT undercamber approach does prevent the "tip stall" issues similarly to washout, it does not address adverse yaw associated with this approach. Generally, FT overcomes this by having and increase in vertical tail area. Overall these are inefficient approaches because if the increase in drag they inherit. Proper washout will have the best of both worlds without needing to increase the vertical tail area. The advantage in a model is that you have a much longer glide path when unpowered and you have less of the typical FT "plop" landings.

Would the Aileron trick address the yaw issue as well? (I seem to remember that being mentioned somewhere...) 🤔

 

[cdfigueredo]

Just a tip for everyone
Many of these sites share the same plans. The difference is in how they organize the plans. Personally I preffer Aerofred, has a wide gallery, but it has an interesting option of filters.
Allows to filter by many parameters, including: flight experience, motor position and / or quantity, wing position, among other options.
This allows less experienced pilots like me, to filter through those models that are easier to fly. If you have an idea of what you're looking for, it's better than going from page to page. Right now Aerofred has 23296... a long way to go page by page.

 

[TEAJR66]

Washout on an ft style wing is pretty easy (or at least the wash out effect).

Full scale wings twist toward the tip, along with a transitioning airfoil profile, to put the leading edge lower.

Rounding the wing tips can achieve this. At the leading edge corner, round it with a radius equal to the length of the front panel. Round the trailing edge corner with a radius equal to the length of the rear wing panel. Using a bezier curve on the rear wing panel can create even more of a washout effect, and increase the
planes aesthetics

For a symetrical folded wing, like the FT 3D, extend the bottom plate past the trailing edge.

 

[TEAJR66]

I used the technique above on this plane and it worked very well.

 

[TEAJR66]

Here is a flight video.

 

[Vimana89]

Here is a flight video.

Anything you do or any extra considerations with the gear to get it to land right in that sort of terrain? I fly in Southern CA in the Mojave desert, so I'd like to know.

 

[Vimana89]

Wondering if that Pixie would fly better if I nix the dihedrals and do elevons, perhaps with winglets, or If I go option B, dihedral just the wingtips and go with RET? Any suggestions? Either way, if one doesn't work, there's always the other method.

 

[TEAJR66]

Anything you do or any extra considerations with the gear to get it to land right in that sort of terrain? I fly in Southern CA in the Mojave desert, so I'd like to know.

I just used bigger tires. Stalling to a plop works as well 😀.

 

[rockyboy]

I just used bigger tires. Stalling to a plop works as well 😀.

I've heard people with the old Lazy Bee's would call out "parking" rather than "landing" when doing a low speed plop!

 

[Vimana89]

That's how I land most of my planes anyway, they are all hand launch/belly land with no gear, and most of em do high alpha well so flop landings are a big thing for me.

 

[Vimana89]

Cleaned up my work spaces and somewhat got some stuff together to start taking on the Pixie. I'll have to make to boom/prow thingy for the low hanging canard sturdy, but other than that, a straight forward build. The original had a dihedral wing but that wouldn't be good with elevons. Dihedral tips would be good with RET, but then I'd have to make a split elevator to retain the same vertical stabilizer. More roll maneuverability and less slop tolerance(elevons), or more forgiving and easier to pilot with a little easier high alpha maneuverability(RET). Guess since the original was free flight and had no control surfaces, the choice is really up to me.

Well, think I'll go RET, and my reasoning is: That funky canard is dihedral, and the original wing was designed with a full dihedral, though I'll probably just do the tips. That appendage and canard would probably make elevon control funky and roll ungainly, so elevons and rolls are out. I'll shoot for good stable flight and clean turns, and good high alpha, and hopefully decent loops. I can always try a second version with elevons another time and see if anything is gained.

 

[Vimana89]

Love this challenge!!. It hit just at the right time to draw me in. Polishing up my latest build and wondering what to do next and where to look for inspiration...this Outerzone goldmine is going to provide me so much material, and all the stuff that turns out good I can submit to this. Perfect.

 

[Vimana89]

Worked on prototype Pixie. I did some hands on experimenting with the suspension for the low hanging canard. The angle of that came out a little different but that should be ok. I changed the VS a bit and increase the sweep and slenderness of the wing a bit too. Just needs linkages and electronics.

 

[willsonman]

Would the Aileron trick address the yaw issue as well? (I seem to remember that being mentioned somewhere...) 🤔

It would work but probably to the same effect and extent that the FT approach uses. Just a hunch but I could be wrong. But then again, there is a reason that is never an option on full-scale aircraft.

 

[kilroy07]

It would work but probably to the same effect and extent that the FT approach uses. Just a hunch but I could be wrong. But then again, there is a reason that is never an option on full-scale aircraft.

Thanks for all the input! I was mainly looking for the “easy fix.” 😉

 

[Vimana89]

Gonna try to get a few minutes more flying on the Kobra/floating kidney before heading to work if I can. Pixie needs finishing, came out funky but if the prototype flies, cleaning it up should be a snap. Moon Crest biplane is next for prototyping, but that will be a full box fuselage build where the original was profile, and will be more an exact replica with less small changes, so if I take my time and nail the build, my prototype may be good enough to submit as a finalized build. Once those three are done, I'm going to perfect them and work on their corresponding threads before starting a new plane.

 

[cdfigueredo]

I think this will be my submission, Bellanca 28-92 Trimotor.

As I don't have 3 equal engines, I want to build it with a single central motor and simulate the lateral motors to maintain the appearance on a scale similar to this thread.
I could try the two side engines and simulate the central one, but all my motors are different.
What do you think? will it work?