Hi Everyone:

Following is an email I received from my ME friend:

"I thought this is an interesting link: http://www.winfoil.com/winfoil/overview.htm. The software is shareware, and seems to have all the necessary tools to design an airfoil (or at least get close to the airfoil of your need prior to the tweaking stage). Regarding the concept for the adjusting mechanism, the approach that I took will require a basic airfoil as a reference start and let's call this the baseline airfoil (which might be a reasonable cambered airfoil for beginner) to be in place for the mechanism to work. As of now, I have not done enough work on this baseline airfoil yet, but the immediate focus will be on the adjusting mechanism to fit within this airfoil volume. The mechanism will be required to put multiple strategic raise points on the skin membrane to allow the camber and thickness change or going to a full symmetric foil, so that having a good reference airfoil start will minimize the tweaking process. However, this task is very difficult to achieve with a single adjustment.

What I have come up with will 'work' (this is an assumption!!) best with a slight taper planform since the compound effect of membrance folding on a taper area is very difficult to control. The coroplast will be the semi-rigid underskin with hinge point at leading edge and hinge/slider point at trailing edge to allow smooth folding (i.e. no kink at attach points during folding). Monocote skin wrap over the coroplast is still required to maintain boundary layer control at the leading edge (and trailing edge?? do not know yet), and at wing tip. The coroplast skin will be raised independently on top and bottom with hinged rods at three spots along the span and two spots along the cord, and this is repeated for left side and right side of the wing. The three spots on the span are tied together to the same control, so that for the left (and right wing) there is (1) common control to raise the first three spanwise spots, and (1) control to raise the next three spanwise spots, and this is repeated on the bottom for independent control. The control will be done by .032 steel cable tension by a guitar tuner tab (this device is worm drive so not backdriving under load). The hinge/slider point of the coroplast skin will be tension with compression spring to stay tight (i think this might not be required since pressure force will keep the skin tight). The wing spar structure will be the structure of the baseline airfoil, and this is the backbone for coroplast skin and the adjusting mechanism. All adjustment will be done at the trailing edge of the wing via the modified worm heads of the guite tuner (the worm head will be flushed with the skin surface). I also look at cost, weight, assembly, and accessibility issues for this concept, and believe that it is more complex than the usual wing but preliminary it could be done. I will have the sketches completed by this weekend."

I have also asked Mr. Peter Young to send me the MIT paper and read it. The paper showed a concept strikingly similar to my original idea. I came to the conclusion that we are on the right track after reading the paper. I have been totally consumed at my work. Nonetheless, I have traded my NIB Edge 540 ARF for a kit built Balsa Nova 120 (excellent workmanship). I was able to get the plans for the BN 120 also.

Bob Pham