Thanks Lowell, that is a very good article that I believe I read years ago, and is the reason I opted for the Hoerner tips to begin with.
Thanks Lowell, that is a very good article that I believe I read years ago, and is the reason I opted for the Hoerner tips to begin with.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
Thanks for posting that link Lowell... and it's also corrected my spelling !. I chose these wingtips because I knew they reduced drag due to W/T vortice reduction and I think I read somewhere else that they also give you an effective increase in Aspect Ratio (beyond the physical wing tip-to-tip span measurement). But Jim, I'm interested in your comment somewhere else on the forum that you tend to get a bit of float on landing with these tips. I'm about 4 weeks off finishing my build and I'm interested to understand why that would be happening before I start on my phase 1 testing. Is your approach speed a bit high or is it just a natural aerodynamic characteristic of this type of tip ?. i.e. greater ground effect due longer effective wing span ....
David
SS7 Builder
David, yes I am fairly sure I get more float on landing, but this is my opinion only; nothing scientific. It makes perfect sense to me, after all the Hoerner tips add roughly 3 square feet to the total wing area-that's a lot. The greater efficiency probably cancels out the increased drag from the area increase, but still maintains the increased lift. These tips probably really help in high DA operations, but are just not necessary for the kind of flying I do. Possibly a good compromise would be to install the Hoerner tips but cut back the inboard edges quite a bit to reduce the added wing area; just keep the fancy contouring near the outboard tips. This still leaves you with a lot of fiberglass work to install nav/strobe lights. Just my 2 cents worth.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
Thanks Jim. I've thought of that very idea of cutting the tips back at the inboard edge but decided against it ... at this stage. As for the F/G work for the nav/strobe lights etc.... I think I've spent more hours fiddling with this and the landing/wig wag lights than I did with fitting up and aligning the cowls.
David
SS7 Builder