Winglet analysis

Incrementally improve winglet design on a given glider by flying with the next generation winglet on the starboard wing with the previous design on the port wing, and seeing which wing rises.

Have I missed something?

What about flying an (e.g.) ASW-24/27/28 with one winglet on and one off? Anyone tried it? (A) the l/d change is huge, and you'd be dicing with death, ( you wouldn't notice the difference. Votes?

Ian Forster-Lewis

I remember reading that someone tried this (might have been Karl Striedeck), and when they got in ground effect during the landing flair they ran out aileron control and could not keep the non-winglet side from dropping.

That would be a 'flair' alright!

Reply. Early testing on ASW-24 winglets I developed used this technique to do basic evaluation of effectiveness. When wing without winglet stalled first and MUCH more violently, we knew we were on to something. The rest of the story is that as soon as the glider departed, it immediately began quick autoratation into spin. Lesson here is that this is not for someone who has not done a lot of spins and not for someone without some serious flight testing experience. I've done more than 300 spin entries testing winglets and can tell you they change characteristics a lot. Take it from somebody that has been there, it will spin into wing without the winglet. As for trying to use this for incremental improvement testing, the difference between a good winglet and a very good winglet in the stall area is minimal. With respect to ships mentioned, '24 has been optomised, '27 factory winglets are very good (M&H are a bit better designed by Mark Maughmer), and '28 is good enough to not be worth even trying to improve.

If it is not too late, see the latest edition of Soaring - arrived in the mail this morning - UK.

George Emsden Moderator - Kestrel Newsgroup on Yahoo <http://groups.yahoo.com/group/kestrel401>

Please mail me your unused ASW-28 winglet before you do the test. I would like to have a spare and you probably won't need it afterwards.