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Does anybody know about this airplane?

Bryan Wood

Well Known Member
Since we were at Bakersfield, CA this weekend I spent about an hour at the Harmon Rocket Fly Inn at L45. The following 9A was parked on the line, but I couldn't find the owner to talk to about his wing tip mods. Does anybody know about this airplane? This is obviously a true experimenter in the spirit of homebuilding and I'm dying to know what he was trying to accomplish and if it worked.
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It looks like this person is making an attempt at controlling the air flow at the tips. on a normal straight wing tip the air tends to move sideways across and over the tip and exacerbates any vortex generated by the tip. That tip treatment helps direct the air straight back along the wing and somewhat reduces the vortex generated at the wing tip.
 
The reason these interest me so much is that so many 9 builders have a heavy left wing initially. I remember reading about somebody's theory a while back that a mold used to build the wingtips put a "Hook" in the left tips causing all of our woes. In his case he cut out a section of the tip and completely redid the glass. This got me thinking that a set of these made up nice and straight will fit any of the planes because of the matched hole and exact fitting components on the skins and ribs. With a set of these that could be loaned or rented out it would be interesting to see if the planes exhibiting problems flew better. This would take out one of the potential problem areas to get the plane flying straight. After the rigging was as close to perfect as the builder could possibly get it, then the parts that traditionally make the plane fly crooked could be added sequentially so any adverse installation would be recognized right off. By these I mean the wheel pants, gear leg fairings, and the tips.

On my plane slotting of the brackets had to be done to get the ailerons in trail in level flight without a heavy wing. Anyway, this was just a thought when I saw the tips on this airplane. When I finally got my plane rigged so the ailerons were in line on the trailing edges of the wings the cruise was up about 5 knots at least.

Anyway, without an understanding of these tips my brain started bouncing around all the above. :rolleyes:
 
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N- Number?

Bryan,

Dija get the N-Number? I can't quite grab it off the photo. Maybe find him on the web?
 
the apparent ans is in another thread

http://www.vansairforce.com/community/member.php?u=935
hope this helps
leon
well this is what mark had to say
"FWIW-- at the bakersfield muni fly-in yesterday-- a guy had a six A with NO WINGTIPS.

he had yellow plates larger than the shape of the wing itself.

IIRC-- he implied that the plane was slower and that he accomplished his goal of NOT bumping into wing tips all the time."
 
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Dreaded Yellow Tail N559W

This plane is registered as a "Dreaded Yellow Tail" serial number 001 and it shows that it is powered by an 0-290. I'm pretty sure it was a 9A because it the horizontal was big and rectangular. At least I think so, but the wing tips distracted me.
 
the guy made it sound like he was always bumping into the fiberglass wingtips in his hangar and/or he didn't want to mess with finishing the fiberglass either.

and he said his plane was definitely slower than ones with the standard wingtips. hope that helps.


edit-- and I said to john harmon as he was going by in his cart, "you see this?" "It doesn't work!" he exclaimed. yeah I know john, that's what the owner just told me but it sure makes for more walking room in a tiny tee hangar. ;)
 
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Just saw this thread... I know the builder by his nickname "Frosty" who lives here in the Antelope Valley. The plane is based at General Wm. J. Fox Field (WJF) so I'll try to track him down and get an answer, Rosie
 
I questioned Bob Axsom about if he had ever experimented w/ some non wingtips like these a month or two ago.....funny how aerodynamics often don't work as it would seem. Wonder why flow fences work so well at mid span (Mig 17/19) and not at the tip?

Glenn Wilkinson
 
Flat plate tips

I spoke with Frosty about this when he was flying his hours off. He said he didn't like working with fiberglass and that they didn't adversely effect his stall speed. They were simpler to build, etc. Reducing span should increase his induced drag, but he says it flies great!

-rob
90976 -- wiring...
 
I questioned Bob Axsom about if he had ever experimented w/ some non wingtips like these a month or two ago.....funny how aerodynamics often don't work as it would seem. Wonder why flow fences work so well at mid span (Mig 17/19) and not at the tip?

Glenn Wilkinson

Swept wings...lateral flow?
 
I work with Frosty at Northrop Grumman in Lancaster at the B2 Division. He is a Mantech engineer, and I have actuactly flown with him in this airplane. He really doesn't like the standard fiberglass wingtips, so he studied the airflow over the wingtips, and decided that airflow over the wing tip didn't affect the performance, so he decided to simply put a flat plate at the end of the wing. I think that he was hoping for some lateral stability, but it doesn't seem to affect that much. The airplane flies solidly and on track without much input from the pilot. The plane is actually an RV9A, and flies very well.
He is a super nice guy, and will be glad to talk to anyone about his plane.

Leonard Streeb
still planning on a 7A
 
Not pretty

so he studied the airflow over the wingtips, and decided that airflow over the wing tip didn't affect the performance

Yeah, there's not alot of lift happening out at the tip of a low AR rectangular wing. I can kinda see his outlook on why the tips wouldn't matter much. We lose some span/area and AR here. But...

With the flat plates extending above and below the airfoil like that, it looks like there'd be some intersection drag between the outsized plate and wing skins, all to try and force 2D flow out there.

The better tip designs I've worked with primarily use planform shape to control tip vortex behavior. Wingtip design is pretty specialized, and it wouldn't be too far off to call it an art, but this doesn't look good to me.
 
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