Carbon Fiber winglet
09-19-2002, 02:25 PM
#1
Carbon Fiber winglet
I am trying to make a carbon fiber winglet.....I know, I know. I could just carve it out of balsa. But I'm addicted to cf.
I want to get a piece of foam and make a piece of radiused cf laminate. Has anyone had any luck laying up their own cf and get the smooth clear finish on the resin? I want to see the weave. I know this probably isn't the clearest way to describe it. Any suggestions are welcome. TIA
Bob Convery
I want to get a piece of foam and make a piece of radiused cf laminate. Has anyone had any luck laying up their own cf and get the smooth clear finish on the resin? I want to see the weave. I know this probably isn't the clearest way to describe it. Any suggestions are welcome. TIA
Bob Convery
09-19-2002, 09:32 PM
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Carbon Weave moulding
Before you go to the extent of spending too much on the idea (which I think has merit) have a ponder for a bit on these -
Make some different shapes, foils etc in balsa and try them out first.
How much effect will they have on the type of model? Are you flying pylonRC, glider duration, what? Remember that their primary purpose is to reduce induced drag so unless that is a high proportion of your drag budget they will probably have less effect than other simpler ideas.
If you want to press on after that the best idea would be to get in touch with someone who has vac bagging facilities.
If you want help with development contact me by e-mail ([email protected]) and I will see what I can do.
Good luck
Make some different shapes, foils etc in balsa and try them out first.
How much effect will they have on the type of model? Are you flying pylonRC, glider duration, what? Remember that their primary purpose is to reduce induced drag so unless that is a high proportion of your drag budget they will probably have less effect than other simpler ideas.
If you want to press on after that the best idea would be to get in touch with someone who has vac bagging facilities.
If you want help with development contact me by e-mail ([email protected]) and I will see what I can do.
Good luck
09-20-2002, 12:22 AM
#3
Carbon Fiber winglet
Oh....I'm sorry, my mistake, I gave you the idea that I wanted them to actually do something. I only want them because I think they are unbelievably cool looking!
I know they make a full scale wing 2 to 3% more efficient...I just want them because of how stupidly awesome winglets make an airplane look. Have you seen the 737-700,800,900 series with winglets? It actually makes the guppy look cool. Any benefit they provide would simply be a bonus.
Hope I didn't burst your bubble.
Bob
I know they make a full scale wing 2 to 3% more efficient...I just want them because of how stupidly awesome winglets make an airplane look. Have you seen the 737-700,800,900 series with winglets? It actually makes the guppy look cool. Any benefit they provide would simply be a bonus.
Hope I didn't burst your bubble.
Bob
09-20-2002, 12:31 AM
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Carbon Fiber winglet
Well, each to their own I suppose.
First up - make sure that you reinforce the wing and wingtip if the model is going to be turning at speed, or moving at high spped. Why? In the first instance you could be geerating considerable side forces which will either rip the winglets off or rip the wingtip off. At speed, there is the likelihood of generating anything up to severe flutter in the winglet. If this happens it is likely to be torsional on the wing (twisting the wing). That could (depending on airspeed) destroy the whole wing.
Second up, just remember that anything you stick out into the breeze from an aircraft is going to affect it in some way aerodynamically.
Again, good luck.
The finish that you want comes from using a highly polished moulding surface and vinyl based epoxy with a coarse weave carbon cloth.
As a p.s. to all that - I fly F1A glider. These things are just about as slow as you can get a model to fly. I had Grantz winglets on it and they did make a difference. The flight pattern for it was quite unusual, in that it had a very slight fugoid path, without the sharp stall usually associated with fugoids. I gave one of the wings to my son to "fly" it in the uni wind tunnel and the best that they could work out was that the effect was caused by the winglets going in and out of stall. This allowed the wingtip to flex from washin to washout (additional angle of attack to lower aoa) and back. How do I know they made a difference? I wiped one winglet off an early model by flying it through a fence. The effect of losing one winglet was (on subsequent flights) to make the model turn in a tight circle with the remaining winglet on the outside and against the rudder (ie the rudder was trying to turn it the other way).
First up - make sure that you reinforce the wing and wingtip if the model is going to be turning at speed, or moving at high spped. Why? In the first instance you could be geerating considerable side forces which will either rip the winglets off or rip the wingtip off. At speed, there is the likelihood of generating anything up to severe flutter in the winglet. If this happens it is likely to be torsional on the wing (twisting the wing). That could (depending on airspeed) destroy the whole wing.
Second up, just remember that anything you stick out into the breeze from an aircraft is going to affect it in some way aerodynamically.
Again, good luck.
The finish that you want comes from using a highly polished moulding surface and vinyl based epoxy with a coarse weave carbon cloth.
As a p.s. to all that - I fly F1A glider. These things are just about as slow as you can get a model to fly. I had Grantz winglets on it and they did make a difference. The flight pattern for it was quite unusual, in that it had a very slight fugoid path, without the sharp stall usually associated with fugoids. I gave one of the wings to my son to "fly" it in the uni wind tunnel and the best that they could work out was that the effect was caused by the winglets going in and out of stall. This allowed the wingtip to flex from washin to washout (additional angle of attack to lower aoa) and back. How do I know they made a difference? I wiped one winglet off an early model by flying it through a fence. The effect of losing one winglet was (on subsequent flights) to make the model turn in a tight circle with the remaining winglet on the outside and against the rudder (ie the rudder was trying to turn it the other way).
09-20-2002, 02:49 AM
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Carbon Fiber winglet
Winglets were popular with 2-meter sailplane pilot for a while, since, when done properly, they do actually produce more lift with the same wing span. What I read in one of those links tossed around in the aerodynamics forum suggests winglets work by converting the energy of the induced drag normally generated by the wingtips in forward flight into lift. If you want to know more about the theories on winglets, ask around in the aerodynamic forum. Ollie and them are usually very responsive and helpful.
But if you just think they are cool and are going for it strickly for the wow factor (nothing wrong with that
) then just about any symmetrical airfoil or even flat plate should work.
But if you just think they are cool and are going for it strickly for the wow factor (nothing wrong with that
) then just about any symmetrical airfoil or even flat plate should work.
09-21-2002, 12:53 AM
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Carbon Fiber winglet
Sideshow,
You need to talk to Tom Dodgen, he works for BVM. That is his airplane and the winglets are his signature, he has them on an old Ultra Viper of his. I think that he built a mold for them but I may be wrong he may have just built them out of balsa and glassed them.
David Reid
You need to talk to Tom Dodgen, he works for BVM. That is his airplane and the winglets are his signature, he has them on an old Ultra Viper of his. I think that he built a mold for them but I may be wrong he may have just built them out of balsa and glassed them.
David Reid
