Help!!!

[bobogofast]

So i took out my frankenstein plane and flew it was on but the tail section turned out to be flexing to much when i applied full power so i have had to take it off. This got me thinking could i just fly it as a wing meaning, using the the wing with elevon mixing and just putting a large vertical stabilizing fin in the back?

 

[bobogofast]

this is what i am thinking so far. idk if the little wings will help or make it worse but was just a thought but the tail is what i will probably be going with unless anyone has some better advice.

 

[Tench745]

The big thing is to make sure your CG is still where it needs to be without the tail. You'll probably be quite nose heavy and the whole thing will be extremely twitchy in pitch. Try it if you're willing to lose the plane. If you're not, rethink. I did this once with one of my crashed designs, it would fly for about a second and go into a climb or dive. I would correct, it would over-correct, and after a few of these oscilations it would dive, flip upside down, and then nose into the ground. Straight wings don't make for great flying wings in my experience. Except, that is, for the Scimitar.

 

[ZoomNBoom]

Using a wing designed for a traditional tail is not going to work for a flying wing. A flying wing, especially an unswept one, requires a special airfoil to obtain stability. You should be able to use a normal wing in a canard, but not with vertical stabilizers glued horizontally at a random angles, inches in front of the cg.

In comic books anything flies, but reality isnt like transformers, it takes some science to make things fly, especially things that dont look anything like traditional planforms. Bobogofast, if you want to design your own planes, especially non conventional ones, you really have to do some reading on aerodynamics and airplane design. Or you can throw that plane and find out it doesnt fly but remain clueless as to why not.

 

[Craftydan]

Using a wing designed for a traditional tail is not going to work for a flying wing. A flying wing, especially an unswept one, requires a special airfoil to obtain stability. You should be able to use a normal wing in a canard, but not with vertical stabilizers glued horizontally at a random angles, inches in front of the cg.

I agree, a little sweep helps make for an easier balance between CP and CG, but the shape of the airfoil isn't as critical as you imply. If you've got data that counters this, I'm not the only one who would be interested in seeing it (unless you're insisting this must be a KFm . . . we don't want this to devolve into a Bernoulli vs. Newton argument).

In comic books anything flies, but reality isnt like transformers, it takes some science to make things fly, especially things that dont look anything like traditional planforms. Bobogofast, if you want to design your own planes, especially non conventional ones, you really have to do some reading on aerodynamics and airplane design. Or you can throw that plane and find out it doesnt fly but remain clueless as to why not.

This comment is inflammatory and unhelpful. The insanely-unpopular-here "google is your friend" comment is at least more helpful than this, because it actually tells the OP where to go look. It also discourages experimentation.

Absolutely, refer people to specific information (threads/sites/books) that would aid people in their design process, but please refrain from this kind of comment.


Bobo,

I do agree with the implied comment from ZnB that the fin below the wing isn't doing you any good. sitting right on top of the CG, it has no lever-arm to counter-balance the strong lifting force from the main wing. It probably isn't hurting, but it's not really helping.

By all means, try it out, but I'd recommend giving it a try first on your apprentice, and at about 1/3-1/4 the current size. put it on the CG and see how it affects the trim, then start sliding it back, being sure to adjust the CG back to the same point -- do this in the unstabilized mode and you should start seeing an increase in needed trim within a few inches. ponder what that means -- what is that extra piece adding to the trim? how does the lever arm amplify the effect?

 

[ZoomNBoom]

I agree, a little sweep helps make for an easier balance between CP and CG, but the shape of the airfoil isn't as critical as you imply. If you've got data that counters this, I'm not the only one who would be interested in seeing it

You need an airfoil with a positive moment coefficient, otherwise you cant recover from large changes in AoA. Thats probably what you meant, but here is some background:

http://www.mh-aerotools.de/airfoils/flywing1.htm

This comment is inflammatory and unhelpful. The insanely-unpopular-here "google is your friend" comment is at least more helpful than this, because it actually tells the OP where to go look. It also discourages experimentation.

The OP has been posting, let say, highly original designs for a while now. I think its honest advice to say that not everything that looks cool will fly. Im not telling him not to experiment, if he wants to try thats totally cool by me as long as his expectations are realistic, but people look at flite test video and may get the impression that just about anything will fly, without appreciating the thought, science and experience that is going in to these designs. I could also have told him "give it a try", but I think we both know what would happen to a perfectly fine wing and more than repairable fuselage if he did try to fly it.

By all means, try it out,

oops, you just told him to try. Maybe you missed the fact that he removed his horizontal stabilizer? Either that, or I missed something.

 

[Craftydan]

Once again I stand by my statements.

Your comment was inflammatory and unhelpful.

If you choose to continue to quibble, you know the consequences. You might not believe it, but I'd rather it not come to that.