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EVO Wing RV-7

G

GatorAviator

I'm New Here
I've seen other threads concerning custom tapered wings, but has anyone seriously considered putting an EVO wing on an RV-7 or -6? It seems it would be a fairly simple mod. Input?
 
Rather than just EVO wings I would love to see an F-7 Rocket designed and built then we could have ALL the goodies!

Glenn Wilkinson
 
Have some

GatorAviator said:
has anyone seriously considered putting an EVO wing on an RV-7 or -6? It seems it would be a fairly simple mod. Input?
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If you know someone who wants to try I have a pair of wings, one has some heavy damage on the outer third but the spar seems okay, and the fuel tank seems okay as well. Mark Frederick thinks it could be repaired with enough effort. They are at his place in Taylor, Texas.
 
osxuser said:
Are the spar stubs long enough for a -6? If so.... :)
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Nope, probably not.

Not to rain on anyone's parade, but I think it would be an enourmous effort to try and fit the EVO wings to anything but the F1 fuselage. Besides, I'm not sure any of the RVs can carry the extra weight and not all but eliminate any gain from the wing design.

You'd be better off building a set of wings from scratch, OR building a fuselage from parts so that you could modify the spar passthrough and the front/rear attach points to match up to the EVO wings. Now that might work.
 
Methinks they're a-coming...

.....because I addressed the tapered wing issue a year or more ago, after a friend (Nick Jones of Formula 1 fame) told me that RV's have too much wing. He said that the area and profile needs to be reduced and large, fowler type flaps to reduce dirty stall speed added. My reply to that was, then wouldn't we have a Lancair copy?

The end result in my mind was that I'd rather have the simplicity and lower stall/landing speed of the RV's....after all, we're doing near 200!

Regards,
 
I understand the desire to go with the tapered wing and Fowler-type flaps. It increases cruise speed while simultaneously reducing stall speed. The EVO wings are a piece of aluminum art, but they are very, very heavy. They were built to Part 23 standards and, in my opinion, are over-engineered for the airframe. Also, they would be very difficult to build by your average garage guy since they require a complex metal jig. The wing tapers (both front edge and aft edge), is twisted (each rib at a different angle of attack), and each rib has a different chord and different thickness as it moves out from the root. I suppose that if you get any of this out of perfect alignment, I'm guessing your performance will be significantly affected. If that wasn't enough, the ailerons are cupped to improve performance.

Besides the set of damaged wings at Mark's. I doubt there's a pair of EVO wings to be found anywhere.

Mark has some ideas for improving the EVO wing IF he decides to put the F1 back into production. If he moves forward with this ideas, maybe a more appropriate wing might be available for retrofit. I don't know if others have tackled the problem and are planning tapered wings. If so, they would be cool. You could probably sell about a thousand of them.
 
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I don't think...

...that the kit was ever finished or any delivered to customers yet.

Also butt ugly:D

Regards,
 
f1rocket said:
... The EVO wings are a piece of aluminum art, but they are very, very heavy. They were built to Part 23 standards and, in my opinion, are over-engineered for the airframe. Also, they would be very difficult to build by your average garage guy since they require a complex metal jig. The wing tapers (both front edge and aft edge), is twisted (each rib at a different angle of attack), and each rib has a different chord and different thickness as it moves out from the root. I suppose that if you get any of this out of perfect alignment, I'm guessing your performance will be significantly affected. If that wasn't enough, the ailerons are cupped to improve performance....
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Randy, Designing to Part-23 doesn't drive structure beyond the safety margin that we already see in Van's wings, which is a margin of 1.5 over a limit load factor of 6. FAR imposed minimum speeds will come into play and require flutter clearance at speeds beyond V_ne, so that might drive control system stiffness / hinge hardware, etc.

Also, tapered surfaces are no more difficult to build - for the garage guy - than rectangle shapes. Assuming the number of ribs is equal, and assuming no twist, its really the same thing. Consider the effect of twisting our RV8 wings, and increasing the rib count - you run into the exact same issues on the rectangle wing that you do on the tapered planform. Closing out the wing near the tip gets tight, but we can easily address this with blind rivets.

The "cupped" ailerons on the EVO wing are due to the airfoil chosen by the HPAI engineer. The MS(1)-313 airfoil runs alot of aft camber (reduced by HPA), which was put there in an attempt to maintain upper surface laminar flow well aft in the section. In practice, this will never happen due to skin seams at the main spar. Aft camber also drives aileron hinge moments up tremendously.

Maintaining laminar flow into the pressure recovery side of the wing is tricky, and in practice will not happen if disturbed by an unblended skin seam, rivet line, etc. You are correct in assuming that skin geometry issues can destroy laminar flow, and it will have an impact on performance, but not a huge one. Kinda like flying a dirty airplane vs a clean one, since we're not laminar past the spar anyway.

I've said in other posts, and again here, that a tapered wing will out perform the low aspect ratio rectangle planform on both ends of the speed envelope, will climb significantly better, roll better, and should weigh less. And it will do all this with less wing area than the rectangle planform.
 
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I can't argue with your background and education. However, I have personally built and worked on both wings. Coulda, woulda, shoulda, is fine in theory. THIS particular wing, as designed by HPAI, would be very difficult to put together without a sophisticated, steel jig which would make one-off building of one impractical IMO. THIS particular wing IS VERY HEAVY, and much heavier than the hershey-bar wing it replaced. Maybe it SHOULD weigh less, but THIS EVO wing doesn't. This is fact, not theory.

I agree with the performance. It does do a nice job of upping the performance on the Rocket, but as I said previously, THIS wing would be too heavy for a RV-7 airframe, again IMO.
 
100 pounds?

f1rocket said:
THIS particular wing IS VERY HEAVY, and much heavier than the hershey-bar wing it replaced.
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A hundred pounds heavier? The F1 Sport empty weight is 1200#, the F1 EVO empty weight is 1300#, I believe the only significant difference is the wing.
 
Mark
The wings themselves, a pair, weigh 65 pounds more then the standard wings. They are considerably stronger with mostly 40 thou skins. The flaps and ailerons are very well built and it would take quite a bit of hangar banging to leave a dent in them. I have seen the HAPI prototype and it is built the same way. The plane would be heavy but extremely strong and would be able to take a lot of abuse. I do not know the status of that project at this time.
 
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