[Courtesy of Martin Brungard mabrungard "at" hotmail.com, July 1999]
I have done a good bit of modeling of the 7035 and a good bit of review of the UIUC data on the 7035. In either case, it was apparent that camber changing is very useful in extending the capabilities of this airfoil.
Regarding reflex, the 7035 doesn't really need reflex to maximize its high speed performance. The modeling I've performed, shows that about -1 degree of reflex is the most that the airfoil will handle. Beyond that, there is no more reduction in drag.
Regarding camber, the 7035 can benefit greatly. The modeling and the UIUC data point to the result that about 5 degrees of camber is all the airfoil will handle. My modeling seems to show that you might be able to stretch that to as much as 7 degrees, but that result may be questionable. Beyond 7 degrees, you are almost certainly adding much more drag and the L/D drops off rapidly.
The UIUC data has camber deflections of 5 and 10 degrees. The low speed performance drops off noticably when you go from 5 to 10 degrees. The area to study for this comparison, is the 60,000 Re curves in the upper lift coefficient range. The L/D is much better at 5 degrees. The camber for launch can be a little higher, since the aircraft is operating at a much higher reynold's number. I'm going by memory here, but I seem to remember that deflections of about 8 degrees are appropriate for launch.
I think this data will point people in the right direction. I find that many people adhere to the old "more is better" philosophy when it comes to camber change. Unfortunately, most people have no guidance on this subject and they have to rely on what everybody else is doing or just judge the performance by the seat of their pants. Unfortunately, its hard to judge minute differences in performance when the plane is a few thousand feet overhead and your pants are nowhere near that plane ;-).
Martin Brungard Tallahassee, FL
"Meandering to a different drummer"