David Shelton
Well Known Member
Jim Smith's tips:
![img0978a.jpg](/proxy.php?image=http%3A%2F%2Fimg683.imageshack.us%2Fimg683%2F4806%2Fimg0978a.jpg&hash=79ab0ae5cea0ef77a35e0f5fdd5cb637)
...A flat tip with sharp edges top and bottom trips the flow around the tip from bottom to top and keeps the vortex near the tip. ...
This would be fairly simple to implement with sheet metal, angle brackets and floating platenuts. I am thinking about it but not now - schedule crunch.
Bob Axsom
Wouldn't it be easier to just attach with fixed platenuts inside the new, flat tips? I don't see what the angle brackets would do.
Sorry Jim Smith, That is too ugly to be on an RV.Chris M
Chris; you forgot to write IMHO! You probably wouldn't like the triangular extensions on my Lancair, or those on the Diamond Katana and the latest Boeing jets.
If I do this I will start with a flat 0.016" aluminum tip plate butted right up against the end of the wing skin. The angle brackets will be riveted to the inside of the tip plates and will extend inside the wing skin aligned with the existing tip mounting holes.
Sorry Jim Smith, That is too ugly to be on an RV.Chris M
Chris; you forgot to write IMHO! You probably wouldn't like the triangular extensions on my Lancair, or those on the Diamond Katana and the latest Boeing jets.
To each his own I guess.. I was just being sarcastic. The legacy's wing doesn't look bad and I don't know about the Diamond. I am pretty familiar with the Boeing planes and I don't recall seeing anything like that on a Boeing.
I saw a 4 blade prop somewhere that had that type of tip on it. It was pretty ugly too....IMHO.
Chris M
I saw a 4 blade prop somewhere that had that type of tip on it. It was pretty ugly too....IMHO.
Chris M
I saw that prop too, on a race plane at Reno-------kicked but t on the rest of the field big time----like 30 mph IIRC
Hi, Mike! We're getting a little off-subject here, but I design props for experimentals. Please contact me at [email protected]. Thanks! PaulPaul,
Are these high performance prop designs suitable and/or appropriate for use in everyday flying, and if so, are they going to be available at some point to the retail marketplace? Thanks.
The old semi-flat tips with the rounded edges are considered offerings to the God of Speed - N_G. If I do this I will start with a flat 0.016" aluminum tip plate butted right up against the end of the wing skin. The angle brackets will be riveted to the inside of the tip plates and will extend inside the wing skin aligned with the existing tip mounting holes. The floating platenuts will be riveted to the angle brackets and pick up the #8 flathead tip mounting screws. After I have the 3/32" platenut mounting holes drilled in the angle brackets using a non-floating platenut as a drill guide I will open the center hole to 3/8" to clear the wing skin dimples. I hope that clarifies the approach. I may start with an oversized tip plate (anyone remember Ron St Jean's Ram Rod 750?) then test and trim and test and trim ... until the edge of the tip plate conforms exactly to the size of the end of the wing.
Bob Axsom
Bob,
did you guys get that space camera going on my hanger? I was sure the lead sheild would prevent it !!
You are thinking what i have started to do. quick and easy and no fibreglass.
..like a lot of the really fast F-1 guys run?
Best,
For Bob Mills:
I see a new flap in your future....might as well get started now.![]()
..like a lot of the really fast F-1 guys run?
Hey Pierre:
Pictures please! I'm aware of the sheared tips, but no upswept versions -- yet. The Evo uses a flat tip, and tufting shows very little upper surface diagonal flow, but than again the airfoil at the tip is only 4" thick and 36" long. I kinda doubt any sort of tip would improve level flight speeds, but I would think a NXT sort of tip might help if any sort of G is put into the equation.
Mike Thompson tried a flat plate tip (clear plexi) -- might ask him for his results.
For Bob Mills:
I see a new flap in your future....might as well get started now.
Carry on!
Mark
I second that motion............since he asked...
Otherwise, it's a bit of drag, opposing some other drag, which didn't
need to be there in the first place.
L.Adamson --- RV6A
Hey Pierre:
Pictures please! I'm aware of the sheared tips, but no upswept versions -- yet.
Mike Thompson tried a flat plate tip (clear plexi) -- might ask him for his results.
For Bob Mills:
I see a new flap in your future....might as well get started now.
Carry on!
Mark
Here ya go:
![]()
They supposedly reduce the vortex to a tighter horizontal "tornado" with an accompanying drag reduction....but hey, what do I know?
Best,
Hey Pierre:
. I think he went back to the flat tip -- I'll check to make sure.
One thing: I sure wish I was talented enough to make parts like that!
Carry on!
Mark
Just type "Paul Lipps" in the youtube search bar, I think it's the first video that comes up...when I clicked on your link,
Hi,
Your experience in the difference in reflex that is best at different altitude reinforces my comments on another thread that at high altitude, induced drag is a bit more important than people might think, because the CL is higher. QUOTE]
Hi, SS! When I had Jim Smith do some testing with my prop on his RV-6, I noted how his speed drop-off with altitude was much greater than mine. I calculated the induced drag for his 4.8:1 AR and saw that it was much greater than mine with its 8.1:1. I commented that he must see much higher nose-up angle at high altitude and he cincurred. I designed some triangular tips for his wings to increase AR without a big area increase, he made and installed them, and it seems to be working well. His area went from 110 to 116, and span from 23' to 26'. His takeoff and landing speeds are lower, his climb is better, and above 6000'-7000' his speed is better. He photographed tufts on the wing-tips close to stall and they were straight back!
The RV-10 airfoil was designed to benefit from a modest amount of reflex at cruise, and I would encourage people to experiment with that too. (how do I know this? send me a PM and I'll tell you)![]()
Bob,
Thanks, though I won't claim the speed is real till it gets confirmed in a race or the side by side testing (great idea Mark!) The flat plate idea sounds like it may be the best of all the tip projects...good luck with that when time permits. What will you use to plug the aileron? I'm still considering the aileron plug along with covering that riblet in the back of the flat tips, but having the plug come loose and bind with the tip is a concern. Terminating the tip at the wing trailing edge and then plugging the aileron alleviates that, so is appealing. Looking forward to seeing the development. Sorry I'll not get to meet you in Taylor Bob...was looking forward to that. But I understand the home front, and thoughts are with you and your bride! Good luck with the fixes and the projects as well, and good luck in the next couple races. Mike will be looking forward to the rivalry as well, I'm sure!
Mark,
Launching early tomorrow, and hope to get to Taylor with a little light left. Will need to swap the tips, but we could make a quick run with the normal (X-C) tips on Friday, then do it again on Saturday am before the race. My cell is 775-544-3511. If ya can, plz call so I can grab your cell to call you inbound. I'm going conservative and planning 3 fuel stops this time, the last one being at E30, 150 miles west. If you'd like, we could meet there (or in between) and fly side-by-side to Taylor and give it a whirl for round 1 with normal tips. Airnav sez cheap gas there. Just watch for the TFR for the airshow to the west.
In the race, let's hope the radome doesn't jam our GPS's again. This time I get to follow you, but I promise to call you if I see you turning too far or too short...I promise!
Cheers,
Bob
Yes, NXT and Jon Sharp have access to Lockheed wind tunnel and CFD therefore I am positive they know more then most of us. They get a lot better data then Bob building 8 wings tips and trying to get flight test data on the differences. (Bob's way is much more fun and in the spirirt of good old American grass roots innovation and I would much rather see Bob's data then NXT data (although NXT data would be cool too, I'm an engineer, the more data the better))...on an NXT at Sun 'n Fun, that was so sharp at the trailing edge, it had a slit tennis ball protecting passersby.
Do they know something most of us don't? Sorry, no pic,
Best,