Comments on: Good news, bad news…

By: Bob Dill

Bob Dill — Mon, 01 Sep 2008 12:04:42 +0000

Bruce,
Bruce,
You are correct that a sheet of chipboard can be made to fly very nicely with sufficient apparent wind and an angle of attack. It can generate almost as much lift as an airfoil at a given wind speed. What it can not do is generate lift with low drag which is why flat/rough shapes are not used for airplane or sailboat lift surfaces.
As for Richard’s explanation, he is trying to keep it at a basic level. As you know, explaining lift to people who have little understanding of hydrodynamics is not easily done.
Bob

By: Bruce

Bruce — Sun, 31 Aug 2008 09:55:19 +0000

The explanation provided under your “how it works” is quite incorrect in your comparison as to how an aircraft flies. A plane’s wing does not generate any significant lift above it, perhaps one-ninth at most. Nor does the behaviour above the wing push the wing upwards as you claim, that would require suction. Most of a plane’s lift comes from the angle of attack of the wing. Most stunt aircraft have zero incidence and possess wings that are equally convex above and below. There is little suction. To compare Greenbird to an aircraft wing was a very unfortunate choice and helps to perpetuate the airplane myth that air behaviour above the convexed wing creates lift by suction. In fact a sheet of chipboard can be made to fly….Bruce+++

By: Em Collis

Em Collis — Sat, 30 Aug 2008 09:10:41 +0000

All the very best, Rich…
I’ve my fingers & toes crossed for sun & wind; following your awesome quest daily. And NEVER believe the forecasters!!

Em.

By: EcObEaN

EcObEaN — Thu, 28 Aug 2008 14:55:30 +0000

oh no i hope you do it !