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Wingtip Changes/ideas. Neep Help!!

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Wingtip Changes/ideas. Neep Help!!

Old 12-31-2003, 10:39 AM
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LearjetMech
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Default Wingtip Changes/ideas. Neep Help!!

Hello,
Rebuilding a wing on an old Royal 40T Trainer. The plane originally had plastic winglets taped on like the top pictue of my terrible rendition. What I think I want to do is put some "tip planks" on the side. There might be another name I'm not familiar with. Is this a good idea? I'm thinking it might serve a dual purpose. One it will provide some protection if a wingtip were to drag (while doing low altitude knife edges of course)! Second I think it might help with "tracking", or act like a small vertical stab! Do you think this is a wise choice, or is it overkill. I have the time, wood, and mind to accomplish it. All opinions welcome! Thanks in advance!
WOW, that looks like POOP!
Nikolaus
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Old 12-31-2003, 10:58 AM
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Ed_Moorman
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Default RE: Wingtip Changes/ideas. Neep Help!!

The upswept wing tips shown will give an effective dihedral increase, giving you more roll due to rudder.

The tip plates will increase your roll rate and lower your stall and landing speed slightly. I have never tried to estimate the speed, but other people have told me 5 mph. A good pilot will be able to tell the difference if you make the tip plates removable.

You might make the last rib from 1/4 balsa with blind nuts on the back side to screw on the tip plates. You could also size them so the plastic tips would fit over them and use a couple of button head screws to attach them. Then you could try all 3, up swept, flat end and tip plates for a nice experiment.
Old 12-31-2003, 11:10 AM
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LearjetMech
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Default RE: Wingtip Changes/ideas. Neep Help!!

The removable idea is good! But I think I want to go the easy route and glue em. The upswept tips originally installed, well are history. One was missing and the other was cracked and busted. Having a single rib out there with no protection IMO, is not good. Seems very fragile and one hit I think would cause me to have to make more repairs.
Old 12-31-2003, 02:02 PM
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ballgunner
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Default RE: Wingtip Changes/ideas. Neep Help!!

I've notice upswept tips on all the newer commercial jets. When they were first used on smaller aircraft they were called splates. Intention was to keep that part of the airflow that goes around the tips instead of over and under directly on the tips for better lateral control. The Robertson tips used by Cessna turn down rather than up. I don't understand the reasoning behind it but I'm not an aeronautical engineer. The reasoning for squared off tips on P-51 types is essentially the same. Airflow tends to go around the tips not over a small portion of the wing. Splates are supposed to counteract that.
Old 01-02-2004, 02:54 AM
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Default RE: Wingtip Changes/ideas. Neep Help!!

On a trainer, you don't need any help from wingtips. The wing itself should have all of the dihedral it needs and all you'll end up doing is adding weight. Just leave the end rib flat and cover over it. I'm not sure if the "extended" end ribs like you have drawn would help, but they would add drag and possibly hurt in a cross wind.
Now if you are doing this just for the fun of doing it, many of the old trainer kits like the Bridi kits used solid tips carved from light balsa. Just basically glue the block to the end of the wing and start carving and shaping the tip to whatever shape the plans called for. In your case, you could do the upswept tip like the original plastic ones. It does require a lot of work and time, though.

Jesse
Old 01-02-2004, 06:22 AM
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SST
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Default RE: Wingtip Changes/ideas. Neep Help!!

No doubt about it, the tip plates will make a noticeable difference in low-speed control and aileron authority throughout the speed range. I use them on almost everything I build except scale, and I modify my purchased planes whenever possible. The larger SST in my avitar has them, and they're great.The smaller one will be getting a set soon.
Old 01-02-2004, 02:13 PM
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DBCherry
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Default RE: Wingtip Changes/ideas. Neep Help!!

Yeah, the tip plates you're thinking of using SHOULD allow the plane to fly more slowly without stalling. The plat will keep the air under and over the wing, rather than letting it bleed off the tip, which creates a vortex at higher speedsand can cause tip stalls when too slow.
Dennis-
Old 01-02-2004, 04:07 PM
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Default RE: Wingtip Changes/ideas. Neep Help!!

As mentioned here, endplates keep the lower side high pressure air from sneaking past the wingtip to the top, reducing the wing's lift. The endplates allow the wing to perform as if it were longer (more effective wing area), and also ensure good flow over the ailerons...

HTH

Jim
Old 01-08-2004, 12:57 PM
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phread59
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Default RE: Wingtip Changes/ideas. Neep Help!!

Me too on the spill plates. I designed my own pseudo high wing fully symmetrical wing plane. Used spill plates on the ends of the wing. Only one flight but it came in deadstick (muffler fell off, previosly damaged and improperly repaired). Instructor said she flew fine. Came in totally under controll at a fast walk.

Mark Shuman

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