Flying wing anhedral/dihedral ?

[Monte.C]

I've read that no dihedral is needed for a flying wing for various reasons, and none is desired because it reduces your aerobatic performance. That means a flat wing is what you want. But what does "flat" mean?

Sorry, I haven't built any of the Flitetest flying wings, but here's my question. See the attached sketch. The easy way to do this is as in the top diagram, where you would build with the wings flat on the workbench. If these wings taper in chord then they'll taper in thickness, and it'll leave you with an effective anhedral as far as I can see. Not a lot, but some. Wouldn't building according to the center sketch be wiser? Or is there no need to go to the trouble?

 

[JasonK]

I have seen wings with dihedral.

the first is the easiest to build and I haven't seen any issue with it when flying stuff. That said the middle _might_ be better, but the difficulty in building that way is probably not worth it in most cases.

 

[JasonK]

also, unless your doing a symmetrical airfoil, you put the flat part on the bottom, so you would end up with the first shape by default.

 

[BlockerAviation]

I've read that no dihedral is needed for a flying wing for various reasons, and none is desired because it reduces your aerobatic performance. That means a flat wing is what you want. But what does "flat" mean?

Sorry, I haven't built any of the Flitetest flying wings, but here's my question. See the attached sketch. The easy way to do this is as in the top diagram, where you would build with the wings flat on the workbench. If these wings taper in chord then they'll taper in thickness, and it'll leave you with an effective anhedral as far as I can see. Not a lot, but some. Wouldn't building according to the center sketch be wiser? Or is there no need to go to the trouble?

View attachment 201724

This seems interesting, I think the only way to tell weather it's worth the trouble or not is to test it. I know my arrow has the top wing profile along with a few other FB airplanes that I have and that my extra 300 has the bottom but I don't really feel the difference. The most neutral flying airplane I have is my Sbach with the centre profile but all of this is probably more related to the overall design of the airplane not this one variable. I think the only way to find out is to test this one variable on the same airplane.

 

[Monte.C]

Yup the top sketch will be a lot easier for sure. Also it lets you embed one or two bamboo skewers in the bottom plate before folding the wing together, which I find really desirable. It just goes against

also, unless your doing a symmetrical airfoil, you put the flat part on the bottom, so you would end up with the first shape by default.

BAM. This man sees the geometry! I never thought of that but I won't be building a symmetrical airfoil anyway.

 

[Monte.C]

Yup the top sketch will be a lot easier for sure. Also it lets you embed one or two bamboo skewers in the bottom plate before folding the wing together, which I find really desirable. It just goes against the physics of the thing. But if the difference is negligible then it is what it is.

 

[Monte.C]

This seems interesting, I think the only way to tell weather it's worth the trouble or not is to test it. I know my arrow has the top wing profile along with a few other FB airplanes that I have and that my extra 300 has the bottom but I don't really feel the difference. The most neutral flying airplane I have is my Sbach with the centre profile but all of this is probably more related to the overall design of the airplane not this one variable. I think the only way to find out is to test this one variable on the same airplane.

Well without question and all other things being equal, anhedral produces a more roll-self-correcting plane. Anhedral of course does the opposite. Specifically for a wing, I mean... What else is it good for besides perfect rolls and inverted flight?

 

[BlockerAviation]

Well without question and all other things being equal, anhedral produces a more roll-self-correcting plane. Anhedral of course does the opposite. Specifically for a wing, I mean... What else is it good for besides perfect rolls and inverted flight?

True, I was more wondering if it would be enough to be noticeable in this context.

 

[Monte.C]

True, I was more wondering if it would be enough to be noticeable in this context.

Me too, and the angle we're talking about is so small, I'm wanting to think like @JasonK who's never seen any issues from building like @ the top sketch. Especially if your wing taper isn't severe.

 

[Air-headed Aviator]

Very intriguing question! When it comes to dihedral and anhedral it wouldn't exactly be unagile vs agile. Dihedral effect is that phenon of turn stability, whether a wing maintains stability in turns. It can be caused by either wing angle, or like with most wings the wing sweep causes the effect! a highly swept wing past 45 degrees can almost fly even without wing plates. Anhedral ends up being instability in a turn, the likeliness an wing falls out of a maneuver. certainly useful in tuning heavy set aircraft that end up being too stable, or allowing computer stabilized aircraft greater agility, like with fighter jets.

 

[JasonK]

he points out here that sweep acts similar to dihedral in effect, so a touch of anhedral (what you were pointing out in the effect of building it) in the build might actually be good

 

[Monte.C]

he points out here that sweep acts similar to dihedral in effect, so a touch of anhedral (what you were pointing out in the effect of building it) in the build might actually be good

Hey I learned that with a little bit of research but I never put 2 & 2 together. That makes me feel better, that the wing sweep can at least counteract any minor anhedral. And of course it's comforting that it seems most people build it flat on the table anyway. I'll stop over-analyzing it now.
Sorted.