Like a hundred tiny remoras....

Great demonstration of separation of the boundary layer during stall. I think this video is from flight testing and data gathering for the ICON A5 project, but it's a cool visualization of what happens during stall.

Very cool, neat to see how the separation progressed outboard as the alpha increased. I'd love to see a demo of a slotted wing a la the Stinson. VGs would be neat to see too though I would imagine that the separation still progresses outward, it just begins at a higher AOA.

And they even had the good taste to do it with the propeller stopped, so it did not have any effect on the flow pattern.

Bernoulis principle is not what lifts an airplane obviously, or the strings would be straight up. Newton musta been right.

Classic

but it's only a slice of the picture. The REAL story is what's happening above and behind that wing. That wing has to influence a volume of air equal to the weight of the plane just to stay level. Wing vortices aside, that's why one would not want to fly across the flight path of a departing 747. How much air does it take to weigh 800,000 to 900,000 lbs?

YB

Yellowbelly wrote:That wing has to influence a volume of air equal to the weight of the plane just to stay level.

Say what?

News flash! There is a difference between weight and pressure!
(does a bicycle tire pumped up to 100 psi weigh 100 lbs?)

kevbert
Say what?


Kiss my mass

The mass of air deflected downwards has to match the mass of the plane being held upwards or what's a physics for??

Yellowbelly wrote:Classic

but it's only a slice of the picture. The REAL story is what's happening above and behind that wing. That wing has to influence a volume of air equal to the weight of the plane just to stay level. Wing vortices aside, that's why one would not want to fly across the flight path of a departing 747. How much air does it take to weigh 800,000 to 900,000 lbs?

YB

The weight of one cubic foot of air is .075 pounds so approximately 11 - 12,000,000 cubic feet of air.

Greg

Yellowbelly wrote:Classic

but it's only a slice of the picture. The REAL story is what's happening above and behind that wing. That wing has to influence a volume of air equal to the weight of the plane just to stay level. Wing vortices aside, that's why one would not want to fly across the flight path of a departing 747. How much air does it take to weigh 800,000 to 900,000 lbs?

YB

I've never heard it stated that way, and my first thought is that it can't work that way. The physics you refer to says that for every action there is an equal and opposite reaction. Mass is not an action, so that isn't directly applicable. In terms of the force holding the airplane up, the lifting force has to equal the mass of the airplane, but nothing about the lifting force has to be represented by a mass of air, I don't think. You've got me thinking, but at this point I'd have to say I don't see the mass of the air as needing to equal the aircraft weight. Despite that, I don't want to fly across the path of a departing 747... Maybe some physicist will weigh in with the details.

Yeah, it's just a thought game. If you try to get the math precise, it gets ugly really fast. Let's just agree that there is a LOT of air moving downwards when a plane flys through a block of airspace: