phrogpilot73
Well-Known Member
Not so much, it works on the same principle as an airplane. They aren't using speed to create a cushion, they are merely staying in ground effect the entire time.
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Crazy Russian Plane-Boat Amalgam with Cruise Missiles
- Thread starter squorch2
- Start date
Oh, it could be, I am just saying what the guy said on the video.
ryan1234
Well-Known Member
It's a pretty common misconception... the whole ground-effect cushion thing....
What actually happens is that trailing vorticies are blocked resulting in a decrease in induced drag. The decrease in induced drag increases the effective angle of attack of the wing..... resulting in more net lift without the drag penalties.
There's a bunch of civilian instructors that still teach the 'cushion' thing....
ryan1234
Well-Known Member
That's what the claim is... I think maybe even 550kts for one of them. Which I kinda wonder about the effects of transonic flow in the ground effect. Seems like they really would have needed a very,very precise flight control system.
Calling it a cushion isn't that far off the mark for a layman's version. The wing moves through the air/the air moves around the wing, the ground gets in the way of some of that air so instead the air pushes back a little bit more on the wing. None of that would happen if the wing wasn't moving and of the ground wasn't there... sorta...
I prefer the more correct explanation about induced drag because I understand it, but for a non-aviation audience I can go with the ten-second "cushion" version and still face myself in the mirror
Food for thought- how does a wing create lift? Do the Bernoullis in the air push harder on the bottom of the wing than the top ones going faster? Or does the wing push the air down and the Newtons in the air push the wing back up? (Answer: sorta both)
ryan1234
Well-Known Member
There's a lot of discussion at APC about the whole lift thing. From my understanding, the common ground between Newton and Bernoulli is in the Conservation of energy, mass and momentum. Bernoulli is all about the conservation of energy, while Newton is all about the conservation of momentum. All of which work of similar principles and can lose relevancy to one or the other (i.e. viscosity, compressibility,etc). The generation of lift is pretty complex, and it's hard to really have an accurate simplification.
There is a lot of BS out there though, like the 'equal transit theory' and 'venturi flow for lift' model.
One interesting note is that Bernoulli studies and principles were a function of an incompressible fluid, like water. So each have their relevancy under a certain set of conditions.
PFM. I don't question whether there are bernoullis or newtons going over, under, or around the wing, so long as they keep doing their thing.
I had a Marine Captain instructor in Primary who said that there was this guy named Bernoulli and he invented these things called 'lift-ees'. Apparently that is what makes an airplane actually fly....
Then I got to helos and learned all about the black magic involved with rotary wing!!!
Then I got to helos and learned all about the black magic involved with rotary wing!!!
I guess there's something to be said for building an entire community around a phenomenon which is still not entirely understood by aerodynamicists.