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  #11  
Old 10-21-2018, 01:30 AM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
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Default Short Wingtips

Quote:
Originally Posted by mattsrv7 View Post
If you can find the carbon tips I'm interested to see how they look.
I made some carbon fiber wingtips for my -8 to use at Reno:

https://scontent-sjc3-1.xx.fbcdn.net...a8&oe=5C87F0E9

The full aileron roll rate is noticeably faster than the stock sheared tips. The tips weigh about 1.5 lbs each, a 6 lb reduction (each) over the stock tips that have Whelen nav light/strobes, landing & taxi lights and archer nav antennas.

Skylor

Last edited by skylor : 10-22-2018 at 12:38 AM.
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  #12  
Old 10-21-2018, 08:13 PM
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gmcjetpilot gmcjetpilot is offline
 
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Quote:
Originally Posted by skylor View Post
I made some carbon fiber wingtips for my -8 to use at Reno:
What Skylor said... If you want fast roll rate NO wing tip (flat plate wing fence) may be better for roll rate (not drag). However RV's are great for aerobatics and have plenty fast roll rate with any stock wing tip. Why do you ask? What have you flown? Pitts, Extra 300, Edge 540, MXS/MX2? If you are a novice to advanced you will love the RV. I don't think RV's are competitive in advanced and unlimited aerobatic classes.

I am an amateur acro pilot so take this with grain of salt, but I have looped, rolled, cuban 8, wing over, immelmann, stalled and spun RV's, and it's fun. I do know some compete in RV's and do well.
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Last edited by gmcjetpilot : 10-21-2018 at 08:25 PM.
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  #13  
Old 10-21-2018, 08:42 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
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Default

Quote:
Originally Posted by Mel View Post
I was hoping to see a reduction in stall speed with the increase in span. Actually the span increase is only at the trailing edge and doesn't increase the area very much.
I perceived no difference in any performance parameters at all.
Aerodynamic theory says that the original Hoerner style tips should be more efficient. My theory is that the slight increase in span/area of the new tips cancels out the loss in efficiency.
Mel, you may well be exactly right here. On low-aspect ratio wings, and wings with rectangular planform (we have both!) Hoerner tips are quite good. The primary benefit of the sheared tip is that it should give very good aileron control deep into the stall. But for a rectangular wing, where the wing stalls inboard first and almost never stalls out on the outer panel, there is not much to be gained -- the ailerons are going to work deep into the stall anyway. As for induced drag, by shearing the side-edge, the effective wingspan is probably not increased over the old Hoerner tips.

A better tip design for induced drag would unfortunately also add a bunch of wetted area, and so the top speed would suffer, except perhaps at high altitude.

On balance, I think the old Hoerner tips are probably the best choice for the rectangular RV wings.
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  #14  
Old 10-21-2018, 09:50 PM
mattsrv7 mattsrv7 is offline
 
Join Date: Jul 2008
Location: Seattle, WA
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My prior airplane to the -4 was a Steen Skybolt and I have a little time in Pitts S2A/B.

The -4 probably rolls a little quicker than the Skybolt did and I like it. I don't have inverted systems and I really miss them. I regularly did outside acro in the Skybolt. Not competition worthy but fun and up high. I really really like the control harmony the -4 has and the light feel.

I'm planning my -7 to be as light as reasonably possible for a day/night VFR machine with inverted fuel and oil. I was thinking about the -415 tips for a little less area near the aileron.

The impact of the tip on the aileron feel and rate isn't easy to estimate so I figured I'd ask. I have thought about a simple tip cap to square it off and just close the end rib.

After the -7 is done an S1 with Wolf wings is next on the list for a project.
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Last edited by mattsrv7 : 10-21-2018 at 09:57 PM.
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  #15  
Old 10-23-2018, 04:16 PM
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gmcjetpilot gmcjetpilot is offline
 
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OP Matt has a good grasp on aerobatics and different designs. RV's are fun "total performance" airplanes but not pure aerobatics, so roll rate is academic wing tips or not. The difference will be small. Roll rate spec of RV's is rated = FUN! The S1 sounds like fun.

If the RV had heavy controls I'd suggest spades but that is not an issue with RV's. The control forces and harmony is excellent in my opinion. There is a limit to roll rate in RV's, without messing with ailerons and controls, which I would not recommend.
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Last edited by gmcjetpilot : 10-23-2018 at 04:23 PM.
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