posted on Jun, 17 2009 @ 12:40 AM
There have been several similar designs over the years - few have been practical and none have really caught on.
Similar performance can be achieved in a more standard airfoil through a combination of shaping and active enhancement.
The cause for stall (also known as a departure from laminar flow - or, simply, a departure) is due to low-energy (slow) air accumulating on the
after-portion of a lifting surface. The fluid (yes, air is a gas - but for all intents and purposes - it's a fluid) then becomes chaotic as vortexes
form and the fluid no longer 'clings' to the lifting surface (wing).
A few bad things happen here. First, you lose a lot of effective lifting area - which means that, usually, your airplane will fall into the ground if
laminar flow isn't restored. Second - since most of your control surfaces are located along the trailing edge of the lifting surface, and that air
is no longer flowing along that surface - you have a loss of positive control on the aircraft (which is really bad since most departures are caused by
intense maneuvers of military aircraft, or otherwise abnormal flight conditions - which makes recovery a tricky process that takes up a lot of
altitude that is not always in ample supply).
Now there are several ways of preventing departure. A rather simple method is dimpling the lifting surface. This causes low-energy air to 'bleed'
into the pours and allow laminar flow to continue over the wing. Shaping the leading and trailing edge of a wing can also improve performance in high
subsonic and supersonic flight conditions.
Active means can include the pumping of high-speed fluid over the 'back' of a wing, which keeps low-energy air from causing a departure from laminar
flow. Other means involve a sort of 'treadmill' that keep the low-energy air from causing a departure.
Some designs (like this one) move the entire lifting surface to prevent departure.
Most are experimental. Some of the passive designs have made it into aircraft - mostly in wing shaping. The F-23 and - to a lesser extent - the F-22
used leading and trailing edge sweeping to optimize the wave and viscous drag generated at supersonic velocities to make supercruise a reality. The
shape is also capable of taking on some very high angles of attack as well as being a very efficient source of lift for each aircraft (better than a
delta wing design, at the speeds they are designed to operate at - below mach 2, above mach 1).
To my knowledge, none of the active methods have ever really been implemented into an operational aircraft. Though there are some active/passive
methods that duct air from around the fuselage and create a vortex up over the body and down along the trailing edge of a wing - keeping low-energy
air from causing problems. However, these require high forward airspeeds.
There are all kinds of little details on an aircraft that look unimportant - a hole here or there that looks like it is there more for aesthetics or
to cut back on weight - when in actuality it serves an aerodynamic purpose, whether placed in by design, or by trial-and-error (don't have to
simulate or understand why a design works to test it and see that it's better, for some reason, than another).