Quote:
Originally Posted by freebeard
If the answer is in the book, I'll say fair enough; but if not...
I took notice of:
Issue: 497 Section: Technical Features 9 September, 2008
The Patent Files: Pneumatic Aerofoils!
Blowing air over wings to give extra downforce!
A VW flat 4 disgorges approximately 1000cfm at 5 psi of engine cooling air. If the boattail rear of a car was as #38 in the patent, how many square feet of cross-section area could be supported pneumatically with that amount of air? |
I think we'll have to go to Ludwig Prandtl's work of the 1930s for this answer.In his book,'Boundary Layer Theory,' Hermann Schlichting refers to Prandtl's work with suctioned and blown wing sections.A photograph is offered of a tufted wing flap at extremely steep angle of attack with perfectly attached flow.
The caveat though,is that this a 2-D flow away from ground effect.Abbott and Von Doenhoff,who wrote 'The Theory of Wing Sections' warn that tabulated data on sections is for 'flight conditions' only.Ground proximity changes everything.
The US NAVY Pilot Flight Manual mentions that wings lose upwash,downwash,and tip-vortices when in ground effect,which remarkably alters their aerodynamic performance.
There is a 4-engined Japanese maritime aircraft with STOL capability derived from blown or suctioned wings.It requires a 5th jet engine to provide the necessary volume and pressure for the air curtain.
Georgia Tech University continues to research 'blown' boat-tailing.As of a decade ago or so,the 'pump' power required to create the effect exceeded the power savings from it.
