winglets

[Guest lyall]

I fly the savannah vg model and i wondered what would happen if you attached winglets to it . It seems that alot of the new higher speed ultralights and GA planes have winglets for higher speed and economy so would the same apply for a 100 mph type aircraft such as the savannah

 

 

[Guest watto]

My understanding is that winglets are a controversial item due to the very small benefit obtained and in LSA they are more cosmetic than anything, I am not sure exactly what they do but believe they are supposed to reduce drag and are effective on larger AC that travel long distances.

 

 

[Guest TFC]

Wingtip devices increase the lift generated at the wingtip (by smoothing the airflow across the upper wing near the tip) and reduce the lift-induced drag caused by wingtip vortices, improving lift-to-drag ratio. This increases fuel efficiency, in powered aircraft, and it increases cross-country speed in gliders, in both cases increasing range.

 

Also it makes the aircraft look cool!!!

 

 

[Cosmick]

Very interesting subject, have a read of these. Looks like there is benefits but a bit of R & R needed to get shape right and how far downstream to place. I wouldn't be surprised if John Gilpins has had a look into winglets.

 

How Things Work: Winglets | Flight Today | Air & Space Magazine

 

A close Look at Winglets

 

 

[Guest Maj Millard]

On the big jets the height of the winglets equate roughly to the same amount of wingspan effectivly, at a certain cruise speed which they are optimized for. Plus reduces drag off the tips. More of a long term gain as opposed to a short term thing. Substantial fuel savings at high altitude, high speed cruise over say 10,000 NM. Yes probabily more to look cool on a LSA.

 

 

[slartibartfast]

I believe they are very effective on LSA.

 

I put a lot of hours on Garry Morgan's Cheetah while building mine. It doesn't have winglets, mine does. The difference is very noticable in speed and stability - especially in the yaw plane. Turns are more stable too - I can put mine into a 60° turn and take my hand off the stick. It just stays there. The other one doesn't.

 

 

[Guest Maj Millard]

That's because the upturned tips on the Cheetah are relativly much larger on the cheetah wing than say they would be on a 747 or a Jab. They are large enough to have a significient effect on the airflow over the whole top surface of the wing, and that is where the in-flight additional handling qualities come from. Because the air over the top wing can't 'spill' off the tip, it then flows straighter over the top of the wing, increasing effeciency. The airflow over the top of a wing wants to flow at an angle toward the tip. You can get the same effect and improvements using small wing fences at strategic pionts, on some wings. One example that I remember is where a builder of an aircraft that had upturned wingtips, decided he would be different and built them down instead. He found he had virtually no aileron control after takeoff because of the change, and was lucky to make it down.

 

The tips on the short-span Cheetah wing are actually upturned tips rather than 'ziptips' like on the jets, which are there purely to smooth out wingtip vortices.The Cheeta wing would certainly lend itselt to airflow tufting to study the actual airflow, if it hasn't already been done.

 

 

[Vorticity]

And a nice bonus of creating the same lift with less wingspan is you can park more planes next to each other in the same space, could be an advantage for hangers filled with LSAs??

 

 

[Guest lyall]

savannah winglets

 

the way the end of the savannah wing is shaped would make a relatively simple fix to attach winglets. maybe the importers or the maufacturers ICP in italy could look at this to see if their are any benefits

 

 

[Guest watto]

Its only a savannah lyall, a couple of 4" nails and some pine and you can run some tests yourself!! hahahhahhaaahhhaa

 

 

[Guest watto]

Joooookkkkking boys, settle down hehe

 

 

[Guest Maj Millard]

I remember seeing a photo of a Russian AN-2 biplane that had experimental wingtips on the top wing in the shape of a birds tip feathers, quite interesting, and I wondered just wether it worked or not as they work fine for birds.

 

The Cheetah is a great looking little aeroplane, and is a good example of what we Australians are capable of turning out, and it didn't take 15 years to get it sorted either. I'm not really a low-wing man but I would have no probs strapping on one of them.

 

 

[Powerin]

If I recall the angled "Hoerner" wingtips of the CH701 and Savannah are supposed to do the same sort of thing as winglets (reduce tip vortices) with less weight. At least that's what Chris Heintz claims on the Zenith website.....http://www.zenithair.com/stolch801/design/design.html

 

 

[eightyknots]

The Hoerner wing tips have the same effect as extending the equivalent 'blunt' wing by 150mm. There is effectively no extra weight.

 

The thing with wing tips is that there is effectively an upturned wing with the issue of added weight. Is it worth it?

 

Perhaps JG3 is running tests on wing tips while we are still only talking about it :-)

 

 

[Gundy]

I remember seeing in a Raaus magazine a few months back a add for a plane called Land Africa it looks like a copy of the Savannah with wing tips on it. Don't know how many are in Oz or how many built but I remember looking at there web site and it stated a MTOW of 450kg not much good here in Oz.

 

 

[Ding]

The new Ninja from the Skyranger stable has winglets. The designers apparently spent a lot of time in the wind tunnel and decided they were a worthwhile addition.

 

I haven't followed up on it, but they may be a retrospective add on to the standard Sky.

 

Cheers all,

 

Ding.

 

 

[Guest Howard Hughes]

Its only a savannah lyall, a couple of 4" nails and some pine and you can run some tests yourself!! hahahhahhaaahhhaa

You might crack 80 knots with some winglets...

 

 

[gregrobertson]

I have spoken to Phillipe Prevot the designer of the Skyranger and the new Nynja about the winglets. They did indeed spend a lot of time in the wind tunnel perfecting the design of the wing tips, it seems it is not a simple matter of just putting something on that looks good, as some of the designs they tried actually increased drag. The winglets on the Nynja do reduce drag but they will will not turn a Skyranger or a Savanna for that matter into a high speed machine. The Nynja is about 10 knots quicker than a Skyranger but the winglets are only a part of the improvement package.

 

cheers Greg

 

 

[JG3]

Yeh, been thinking about them, but no action yet. Too many other things more pressing, and I'm not real optimistic about the benefits on our aircraft. There's some claims around, but I've yet to see any real life comparison tests on aircraft. Differences that can be measured in a wind tunnel don't necessarily carry through to real life aircraft ops enough to be worthwhile. And since they're such a tempting opportunity for manufacurers for image marketing, as a skeptic I'm prejudiced on the suspicious side already......

 

JG3

 

 

[eightyknots]

Differences that can be measured in a wind tunnel don't necessarily carry through to real life aircraft ops enough to be worthwhile.

I have read quite a bit about wind tunnel test and how, in real life, the claimed benefits have not eventuated. The necessity of real life testing is highlighted on your excellent stolspeed website.

 

I still wonder about the efficacy of winglets on an 70-90 knot ultralight. May be it's worth the weight penalty? I have also read of a vertical straight edge being used close to the wingtip, in line with the airflow. This piece of metal was both light and effective in reducing around-the-wingtip induced drag and turbulence. Apparently this has been used to good effect in some instances. I wish I could remember which book I read that in. Either this or the winglets are worthy of investigation.

 

 

[Mick]

As has been said about the Skylark with it's large winglets, not sure if they are an efficient aerodynamic device or a clever marketing ploy but either way they work!!!

 

 

[eightyknots]

This is a very interesting slideshow showing all the different types of wingtip devices, including some I had never heard of.

 

Well worth a quick look: http://www.dept.aoe.vt.edu/~mason/Mason_f/WingtipDevicesS04.pdf

 

 

[dazza 38]

This is a very interesting slideshow showing all the different types of wingtip devices, including some I had never heard of.Well worth a quick look: http://www.dept.aoe.vt.edu/~mason/Mason_f/WingtipDevicesS04.pdf

Very interesting.Thankyou eightyknots.