rv969wf

rv969wf

Well Known Member
I'm wanting to see if anyone has tested wing tips or experimented with them, meaning less drag,, more speed. My RV-6 has "Massey" wingtips. I love the looks of them and I like the landing/nav lights in the tips and not in the wing. www.masseyaircraftservice.com My wingtips were installed in 1998 and have not been removed since. I know that Van's has changed wing tip designs over the years as well as Rocket and a few others. One thing that I learned from Massey Aircraft about their wing tips lately is this: There instructions ask you to sharpen the edge of the tip approximately 38" from the trailing edge to the front. (Make sure it's sharp).... By having this sharp edge, they claim it keeps the air from flowing up around the tip and creating turbulence. OK my wingtips have rounded edges and are smooth because they were done 8 years ago. I got curious about this so I did some tuft work around the wingtips on top. Flew the plane and the very corner of the tip tuft string was twirling like mad and completely turned to fuzzz in 10 minutes. Vortex I guess coming off the tip, but all of the other tuft strings seemed to stay attached to the skin of the tip / wing along with the aileron and the rest of the tuft strings were all straight. Test #2. I cut a .060" thick strip of plastic 1/4" wide x 38" long and taped it on the wingtip very carefully with aluminum tape, no wrinkles etc. in the tape. Flew the plane and what I noticed was that the tuft string at the tip was only rotating in about a 1" circle as opposed to a 3" circle before doing this. The tuft string did not frazzle as badly by adding the strip of plastic for testing. Did it go any faster, I don't know, I only did one wing tip and it was a different day hotter etc. I'm going to try a few other things and see what happens. Has anyone tried any of this or tested other wing tip designs or am I only talking about 1/2mph gain????? or making things worse. Fire back if anyone has any thoughts on this. I'll listen to any comments that anyone has. Yes I like to experiment!! But SAFETY COMES FIRST BTW....AJ
 
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I went out and checked a pair we bought from Massey's. They look like they could be sharper but there's definitely an edge. 38" like you said.

basically if a guy unknowingly rolls over the edges he will round off the sharp edge they're talking about.

I was also told if I do all the speed mods avail. out there-- I'll have a 400 mph airplane. :)
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Excellent experiment

rv969wf said:
I know that Van's has changed wing tip designs over the years as well as Rocket and a few others. One thing that I learned from Massey Aircraft about their wing tips lately is this: There instructions ask you to sharpen the edge of the tip approximately 38" from the trailing edge to the front. (Make sure it's sharp).... By having this sharp edge, they claim it keeps the air from flowing up around the tip and creating turbulence. OK my wingtips have rounded edges and are smooth because they were done 8 years ago.

....did some tuft work around the wingtips on top.....corner of the tip tuft string was twirling like mad........all of the other tuft strings seemed to stay attached to the skin of the tip / wing along with the aileron and the rest of the tuft strings were all straight.

Test #2. I cut a .060" thick strip of plastic 1/4" wide x 38" long and taped it on the wingtip very carefully with aluminum tape, no wrinkles etc. in the tape. Flew the plane and what I noticed was that the tuft string at the tip was only rotating in about a 1" circle as opposed to a 3" circle before doing this. The tuft string did not frazzle as badly by adding the strip of plastic for testing.

Did it go any faster, I don't know, I only did one wing tip and it was a different day hotter etc. I'm going to try a few other things and see what happens. Has anyone tried any of this or tested other wing tip designs or am I only talking about 1/2mph gain????? or making things worse.
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Alan U da Man.

Yes you are giving out secrets. I have it on good authority that making a VERY sharp edge, knife sharp, along the wing tip edge is goodness. That is of course the symetric wind tip not the older horner style. I got this from gurus of RV speed.

Look at tracy saylor RV6 or dick martins RV8. I suspect Dave Anders RV4 also had the knife edge wing tip treatment. BTW Dave's RV went +240 mph at this years airventrure x-c race, coming in second to a glasair by just a hair. (see this months RVator). I think dave was saving fuel since he only has 32 gal.

I have seen Massey Aircraft products and they look nice, but save your money. You can modify Van's wing tip.

Yes van had two symetric tips, the first Bat wing or shear tip (replacing the horner tip) and one later which was slightly modified with more of a straight or flat trailing edge. They also increased the recess size for more tip lights, which is no consequence to aerodynamics.

Does it work? I have not tested it. I have it on good authority its a worthwhile mod. Please report back with you findings. My opinion is we are splitting hairs. Improvements will be small, but for some builders (like you and I) it's worth it. I am going to do it.

Can you measure the speed increase? You are already going fast, so the gain may be hard to measure, may be not. I am thinking like you 1/2 mph. It could be a nice surprise. Like you say, it has to be real sharp and thin with a little fillet.

I did not get the exact spec or how wide to make it or the extent along the length. I had assumed it extended further aft? However from your test it appears it's needed mostly in the front.

Like anything there is a trade off, it can't all be good. Adding a little knife edge strip may be good, but adding too much creates a loss. It's lowering parasite drag verses adding induced drag, like a winglet, its not all good. It has to be done right. Clearly if its not straight it could create some roll moment and more drag than less.

Look forward to hearing about your findings.

Cheers George

mark manda said:
I was also told if I do all the speed mods avail. out there-- I'll have a 400 mph airplane. :)
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You where told that? :D I guess dave anders with his +250 mph RV4 is slacking. :rolleyes: Mark can you tell me and Alan if that lip is bonded on after the tip was made, or is it add on. Does it have a radius? How wide is it? Thanks
 
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Tips

Maybe a little off topic, but have read that the bat wing tips from Van's add about some wing area and therefore decrease wing loading, which Van was quoted as saying he liked (RV-7 test in Sport Aviation). You'd think added wing area would increase drag a little, perhaps to decrease speed? Or is the lower wing loading offsetting? Anybody out there know about this? Bill
 
I am the lazy8 bloke :D

When I bought the tips from Massey, they told me to keep that edge sharp. So, I did. I don't have any data on any other configuration. Sorry. I actually bought them because I thought they looked better than Van's Hoerner tips, which were the only ones available at the time.

At the time, Tracy Saylor told me that he gained 2 mph in top speed changing to these from Van's, and also that his stall speed was 1 mph lower.

I was told by a Cessna engineer that drag at the tips of things...wings, verticle stab, h-stab, etc. is important. Still, my feeling is that once you fair in all the lights, you are probably splitting hairs.

But, hey, those of us who like to do this stuff, like splitting hairs, so why not? And, all those 1/2 mph mods have to add up eventually.

Have fun!
 
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Thanks John

Thanks John for the input!! I agree every 1/2 to 1 mph makes a difference, it's just a matter of how much time one wants to spend to detail on little things. I think YOUR -8 is awesome. You've done your homework and built a quality Fast / Speedy airplane, keep up the good work. Thanks again for the input. AJ
 
I have them on my 7

I couldn't remember where I got the idea to do this but that is it. My 'puter crashed and I lost the resource. I built these on my 7. I've attached a couple of pictures. A good friend of mine who used to be nationally known sailplane competitor and aerodynamic specialist looked at the mods. In very brief summary, he said it was like adding wing span. The sharp edge would cause the air to separate away from the tip. The result should be improved efficiency, smoother control and more speed. Don't know for sure because I have no baseline for comparison. Robbie Attaway has about 10 hours on my plane and says it is the smoothest RV he has ever flown.

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Was it sparky?

Darwin,

Which aforementioned glider guru?

Just so I follow you, are the sharp ledges in the pictures, on the very end of wing tip, or are they on the leading edge. Kinda resemble stall strips.

Tim
 
Jerry Robertson

Jerry Robertson was extremely active and well know in competitive soaring achieving virtually everything during his time. Tim, you probably recognize the name because he took on RC soaring a did very well in the major contests.

I'll send you a private message with some additional pictures.
 
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