For you speed mod types

panhandler1956 · #1 07-02-2010, 01:28 PM

Found this today. It is intended for transport category equipment but I thought you speed-guys might be interested. Probably not alot to gain with a 200 mph RV, might even be draggier but it looks interesting.

Obviously, they are channeling the wing tip vortices.

Link:

http://www.gizmag.com/minix-wing-tip...icture/116756/

rvmills · #2 07-02-2010, 02:19 PM

Interesting to be sure. Claims to be better at tip vortex reduction than blended winglets.

There's a gent up in Canada that is contemplating a blended winglet for small GA airplanes, and the RV is on his list. I spoke to him, but it requires replacing the outer wing rib with his rib design that accepts the structural support for the winglet. Not sure I'd want to go that far, as I'd want to be able to swap tips dependent on the mission, and my gut says winglets just might impact aerobatic capability

.

This design looks as though it could be designed somewhat plug and play, with little to no structural mods (perhaps...but that is total speculation...who knows what aerodynamic wing bending/twisting forces would be applied throughout the entire flight envelope).

Something to keep an eye on to see if it gains any traction and lives up to expectations.

Looks cool though, and that's worth a knot or two!

Cheers,
Bob

pierre smith · #3 07-02-2010, 02:30 PM

...several years ago, someone was making winglets for our Air Tractors claiming improved airflow and less intense vortices that impact our chemical spray pattern.

It didn't take long for Air Tractor to warn any owners that their spar life would take a 40% hit if they installed them! My 8000 hour spar (Which I've replaced) would then become a 4800 hour spar

Best,

scsmith · #4 07-02-2010, 11:47 PM

Ah come on guys, don't EVEN get me started......

rvmills · #5 07-03-2010, 12:11 AM

Quote:

Originally Posted by pierre smith

...several years ago, someone was making winglets for our Air Tractors claiming improved airflow and less intense vortices that impact our chemical spray pattern.

It didn't take long for Air Tractor to warn any owners that their spar life would take a 40% hit if they installed them! My 8000 hour spar (Which I've replaced) would then become a 4800 hour spar

Best,

Pierre, its those unintended consequences that concern me as well. Reshaping tips to find lower drag/higher speed is one thing. Adding things that radically change the characteristics or create unwanted aerodynamic forces is quite another!

Quote:

Originally Posted by scsmith

Ah come on guys, don't EVEN get me started......

Steve, please go ahead...always good to hear the view from the Aero Engineer's seat. I know winglets are optimized for high and fast (as in jet high/fast), and this tip says 6% at .8 mach. The likelyhood of either being effective at RV speeds is likely low, and the design strength consequences could be high. No intent here to use either, but always willing to learn from the discussion.

It looks innovative and kinda neat at one look. OK, it also looks like one of the new beer bottle swirl tops that supposedly makes the brew pour faster too.

But interested to hear your thoughts...and still looking for the magic wingtip (OBTW, have talked to many racers, and no one has really found the magic tip...lots of theories, some increased speeds...but no clear "perfect" tip).

Thoughts? Starter button pushed!

Cheers,
Bob

dhammer · #6 07-03-2010, 05:46 AM

Quote:

Originally Posted by rvmills

Thoughts? Starter button pushed!

Cheers,
Bob

When they say it is 5 times more effective than winglets my BS dial goes up.

The APB winglets retrofitted to the B-757 gain at least 4 1/2% according American Airlines and they are not just a bolt on deal. The last 10 ft of the wing planks get cut off and replaced. Also, the spars get beefed from the pylons to the tip to handle the additional bending moments. The $1.2m cost for them gets paid back in less than a year in fuel savings. Originally they were only going to mod 22 or so of them, but now are doing the fleet.

If winglets are only for high speeds then why do the latest gliders have them for performance? It certainly isn't to look cool. check out http://www.dg-flugzeugbau.de/leistung-e.html for one manufacturer's opinions on how to increase performance.

David Paule · #7 07-03-2010, 07:42 AM

Why would you want to put a deer whistle on your wingtips?

rvmills · #8 07-03-2010, 12:05 PM

Quote:

Originally Posted by dhammer

When they say it is 5 times more effective than winglets my BS dial goes up.

The APB winglets retrofitted to the B-757 gain at least 4 1/2% according American Airlines and they are not just a bolt on deal. The last 10 ft of the wing planks get cut off and replaced. Also, the spars get beefed from the pylons to the tip to handle the additional bending moments. The $1.2m cost for them gets paid back in less than a year in fuel savings. Originally they were only going to mod 22 or so of them, but now are doing the fleet.

If winglets are only for high speeds then why do the latest gliders have them for performance? It certainly isn't to look cool. check out http://www.dg-flugzeugbau.de/leistung-e.html for one manufacturer's opinions on how to increase performance.

Hammer,

My BS flag was pegged when reading the article as well...why I mentioned to watch and see if it lives up to expectations. For something to be that revolutionary is very unique, especially when we often see something "new", only to find aerodynamic research from the early 20th century that already has tested and debunked or dis-proven a theory or modification. So I'm with ya!

I also fly wingletted jets (737's in my case) at work, and concur with you...no easy bolt-on mod. But as you said, the fuel savings are phenomenal. Could it work for speed with an RV...dunno, but its fun to contemplate.

SARL chairman Mike Thompson did some flat plate add-ons to his flat wingtips that were like a fence above the top skin at the outer edge. They loaded up his ailerons and made roll forces uncomfortably high, so they were pitched.

Bob Axsom and I have been playing with flat tips as well, and all three of us are still contemplating testing flat plate fence-like add-ons that fair to the wing top before they get back to the aileron...either above the wing only, or above and below the wing (think A-320-like tips, but a bit more curved). Wish we had a wind tunnel, and AVC and OSH are on our radars before this type of project. But it's all in the spirit of experimentation and innovation...with a keen eye to safety...none of us want to experiment with no regard for risk!

I probably bit a little hard on this thread, but when things like this pop up, its a chance to gain wisdom from the group during discussion. And honestly, it also falls in the category of "education and entertainment"!

Quote:

Originally Posted by David Paule

Why would you want to put a deer whistle on your wingtips?

David,

I thought of the whistle-factor too! The only reason I can think of is to sound like a Corsair!

Of course, noise probably means drag, right!

All in good fun!

Cheers,
Bob

panhandler1956 · #9 07-03-2010, 01:49 PM

Probably be cool with a smoke canister attached!

RV8RIVETER · #10 07-03-2010, 02:15 PM

Actually, I have seen something similar before. A French Aero Eng instructor built a homebuilt and put round tube wing tips on it. He claimed an efficiency gain from it. I posted a link to it years ago on one of Bob Axsom's threads, but can't locate it now.

Looking up Minix looks like it is a French company. I wonder if it is the same guy and if he has optimized his design?

An interesting comment here, post #16.
http://www.oshkosh365.org/ok365_Disc...id=3339&page=1