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Originally Posted by aerohead
The concept has been demonstrated in aviation since the 1920s,with blown slots on wings,in Ludwig Prandtl's research.
There are STOL aircraft which use it today.
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Blown flaps (front and rear of the wings) have been used on many aircraft - don't have to be STOL designs.
Taking bleed air from jets.
Or using the engine exhausts as a blower above or more traditionally, under the wings.
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Historically,the pump absorbs more energy than is saved with the slot.Not an issue with military aircraft.
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Oh, it is, but there's power aplenty in the take-off phase to spare some bleed air.
Especially if it increases lift when that's what you really want.
On landing, it's just a function of not throttling back the power as much which is also OK as higher power settings tend to improve throttle response, which was sluggish in the early days.
Then dump the power by creating more drag (and lift along with it).
Quote:
Originally Posted by Hypermiler1995
(I wish I could post pics correctly  ) I drew a car that used ducts through the side to guide air from the nose, around the side, and out the back into the wake without boattailing.  But it takes away from the space in the car, would cause some drag itself due to curves the air would go through, and its totally a nightmare for the back glass |
Ducting doesn't really work - it's essentially the complicated and expensive way to reducing frontal area.
"Wetted" area is increased
You get interference drag between the various "pods" that reduces or eliminates whatever is gained.
That's on top of the issues you already pointed out.