Need help with combat wing

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centralnchunter
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Need help with combat wing

Post by centralnchunter »

Self designed combat plane. WS 62.5â€
centralnchunter
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Post by centralnchunter »

I forgot to mention the airfoil(s). I found the airfoils on the net and were supposed to be good flying wing airfoils. The center section and outer wing panels at the root are MH45 and the wing tips are Skipkill 1.7/10B.
centralnchunter
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Post by centralnchunter »

I put on some strapping tape and used the heat gun to force more washout at the wing tips. I'll test fly it in the morning and see if that improves the way it fly's.
Hat Trick
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Post by Hat Trick »

What is the weight and wing area. My guess is that the wing loading is to high. The wing looks pretty samll in the picture.
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tmelton
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Post by tmelton »

You could try some type of leading edge slat to change the lift on the wing. I don't know if that would be against combat rules or not.

You could also try adding some negative or positive reflex to move the center of lift on the wing. That changes how the plane will respond to the elevator. With reflex a little goes a very long way so only make small changes.

You could also try some type of canard on the front to make your wing fly more stable. That could be as easy as sticking on a couple of pieces of 4 mil or making an extension for more leverage.

All flying wings need some reflex. I would start with that if the wing loading is good.
centralnchunter
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Post by centralnchunter »

WS 62.5â€
centralnchunter
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Post by centralnchunter »

I made a quick test flight. With the added washout at the wing tips it turns tighter now than before but it has a much worse inverted flying quality. Outside loops are huge and are not easy to perform. I'm ready to pull the gear and start something else....
THend
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Post by THend »

Check out the North County Flying Models site for trimming the Moth. It may help you a ton. I can't see the image because work blocks it..

What you want to do is to go into a very steep dive, throttle down and see what happens... The plane will tuck under, fly straight down, or pull out... I can't remember all the details of which means which..but I remember it is not intuitive.

http://www.northcountyflyingmachines.com/FAQ.htm

The difference between a great flying wing, and one that will give you fits is less than 1/8 shift of cg..

Is your fuel tank dead on the cg? If not, as fuel draws it will shift the cg on you...
centralnchunter
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Post by centralnchunter »

Thanks Terry. I'll check that site out when I get a chance. Mine is electric powered. I didn't realize such a small change in CG on a flying wing has that much of an affect. I usually only move the CG in that small incriments fine tuning the plane. Not working out design kinks. :0 I think it's too far forward right now.
I tried making a fence post plane a pusher. Well I actually I did make it a pusher. Was a little tail heavy but it flew. I think it flw a tad better in tractor conf., but that could have just been because it was tail heavy. It flew a lot better than the wing anyway. I'm almost ready to scratch the idea of finding a pusher platform and just buy motors as requied from midairs/lawndarts.
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tmelton
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Post by tmelton »

Angle of attack, thrust angle, Center of gravity, and center of lift all efect how the plane will respond to the elevator. Very small changes to center of gravity or center of lift with a wing or a short coupled plane can make huge changes to the way it flies and loops. I heve found that a couple of turns to aileron linkages can make a short couples plane snap out of a loop or prevent it from snapping out. I would crank both aileron linkages out or longer by 2 turns and give it another try.
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tmelton
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Post by tmelton »

OOPS. It should be in or shorter so that you get some negative reflex.
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o1moregil
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Post by o1moregil »

not all flying wings need reflex, the Flying wings I been using are set to zero.
THend
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Post by THend »

Ok, I can see it now...

That is basically a ZAGI...

Check out on the web how to set up a ZAGI with power..

Ultimately that thing or similar designs I've seen...will tear up the sky..

Go to RC Groups or something like that...

It is a flying wing, but not what I was imagining... the sweep gives you some leeway in cg placement.

For that kind of wing, glider that is... I set the CG sooo far back it is crazy....

Do a search on CG for a Chevron wing...which is what that is.. but with a power pod.
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Post by rsieminski »

So what is the general rule of thumb to follow, when setting up the CG on a flying wing?
THend
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Post by THend »

That is the question, but it has to start with what type of flying wing..

You have the Falcon and the Mako, you'd think the set-up would be the same for CG but it isn't...

Straight LE or highly swept LE... then elevons only or Ail+Ele...

For the Chevron wing there is info out there, like I said, I'd check the Zagi info first..

As for a straight or near straight LE plank type wing the CG can be at 18-22 % MAC..

RC Groups has a decent forum for design etc.. I'd check it out.

Clear as mud now ehhh..[:p]
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