Hey Tom,
I know it looks odd, but that airfoil came together kind of as a joke and it worked. I did a physics project in college when a friend I were playing with CL a bunch. We were measuring model wing lift in a wind tunnel using a wing with a set angle of elevation and a load cell for measuring force. I drew out that "diamond" airfoil, (note, the bottom is shorter than the top) and on a cocktail napkin at Mitches Tavern in Raleigh, NC after a lot of drafts said, wonder how this will work? Turned out it worked as good as , if not better than most of the classic foils we were testing. Plus it was easier to cut out and required little or no sanding if you were good with the razor.
Most of the planes I've used this on will ROG without any up elevator. Nice evn climbs. Much Elevator input will cause a stall until you build up a half lap speed or so. You can't use a crossspar on the edges or it wont work, like you said, the covering shrinks in and makes a great airfoil. This is the biggest plane I've ever tried it on, but with the twin booms, I'm really not supporting that much weight on the outside. Seems nice and tight anyway.
COG without the engines is about a 1/4" behind the back Lead out, so with 2 061's it should be at the front one or maybe right on the LE. Don't really care though as long as it flies. I built it as a "Man that is a cool looking plane" model instead of as a stunter (which I inevitably crash and bust into a million pieces)
As far as drag goes, my Green Giant (30+" span seen below) used the same airfoil and AP Wasp engine. It was clocked by my best friend, who is a sheriffs deputy, at 48 mph at the beginnning of a tank and 53 mph at the end of the tank, so it runs PLENTY fast.
Topic: 1/2 A Twin (pics) (Read 1199 times)
