90* flying

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gcd89

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Greg D.
Can someone explain the dynamics of 90* flight? I believe another name for it is "knife edge" flying? I'm talking about this

4877948108_97d393556b.jpg


Does you elevator become a rudder and your rudder become an elevator? How do you fly like that in a straight line?

Are all planes capable of this, or does a plane (and control surfaces) have to be specially designed for it?

The angle of attack and angle of incedence change when flying like this right? How does that work since the wings are no longer generating lift by deflecting air toward the ground?
 
The PFM pump is what produces the Pure F-ing Magic that keeps the plane in the air...:D It creates lift along the fuselage, the rudder is "pitch" controlling as you suspected.
 
Henning said:
The PFM pump is what produces the Pure F-ing Magic that keeps the plane in the air...:D It creates lift along the fuselage, the rudder is "pitch" controlling as you suspected.
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LOL. I thought you were talking about a fuel or oil pump or something.
 
The plane isn't really flying as much as it is hurtling through the air. The airplane could not sustain flight in this configuration.
 
jason said:
The plane isn't really flying as much as it is hurtling through the air. The airplane could not sustain flight in this configuration.
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So really, the only way it's staying up is the thrust is overcoming the other forces acting on the plane?
 
jason said:
The plane isn't really flying as much as it is hurtling through the air. The airplane could not sustain flight in this configuration.
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If it has enough power, it can sustain it until the fuel runs out. Newtons laws apply to everything. A wing is more efficient at flying, but anything that can deflect > it's weight in air downward can fly.
 
Henning said:
???:confused::confused:Isn't that what flying always is?:confused::confused:???
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Not really...flight is lift AND thrust overcoming gravity/weight. In knife flight the wings aren't providing lift, right?
 
gcd89 said:
Not really...flight is lift AND thrust overcoming gravity/weight. In knife flight the wings aren't providing lift, right?
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And you get lift without thrust how? Without thrust, nothing heavier than air flies. Airplanes get thrust from engines, Gliders get thrust from nature in the form of thermals and such, but you always have to add energy to maintain altitude or climb. Lift of a wing is created by thrusting the airfoil through the air and deflecting the same weight of the air down as the weight of the plane in unaccellerated flight.

In Knife edge the wings are not providing lift perpendicular to the core of the Earth, no, the fuselage and vertical stab is doing that.
 
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gcd89 said:
Not really...flight is lift AND thrust overcoming gravity/weight. In knife flight the wings aren't providing lift, right?
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Wings ain't do'n **** during knife edge - you get some lift of the sides of the fuselage and rely on thrust from nose up to do the rest. Even with just a little IO-540 in a nice light weight airplane like a Pitts or Extra (or a big honkin jet) you can fly quite a while in knife edge.
 
Unlike a Pitts, you will not see a jet sustain true 90 degree flight. What looks like 90 degrees might actually be 80 or 85 degrees, which at high G still has the potential for enough of a vertical lift component to maintain altitude. And jets have so much speed and momentum that if they are climbing slightly and roll true knife-edge (90 deg) it takes a little while for them to start descending again. Makes it look like they are actually sustaining flight in this attitude.
 
Never seen a real knife-edge in a full scale plane.

In the R/C world its one of the basics.
Granted, in the R/C world 1:1 power/weight ratio is common, and so do over-sized control surfaces.
Note that unless your wings are 100% symmetrical you'll need to hold some down elevator to compensate for the "horizontal lift".

 
I should have used the word "Sustained" knife-edge instead of "Real".

Can the Pitts do a 90 degree knife-edge for say, 2 minutes without losing altitude?

That's actually a pretty cool video!
Thanks!
 
ICBMS are big tubes with little fins, and they fly just fine. The first sentence in my first book is if you put a big enough engine on anything, it will fly.
 
gil_mor said:
I should have used the word "Sustained" knife-edge instead of "Real".

Can the Pitts do a 90 degree knife-edge for say, 2 minutes without losing altitude?
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Sure, not that there's a reason to. There's nothing special about it, and it takes no skill...just looks cool to the airshow crowds. Simply takes an airplane with sufficient power, rudder, and fuselage side area....any Pitts will do. A Stearman would have trouble. Many setups have oil pressure issues in knife edge attitudes, so you won't find them spending a long time there, not that it can't be done...but again, pointless. Also, spending several minutes in knife edge would get your CHT's pretty hot.
 
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Henning said:
If it has enough power, it can sustain it until the fuel runs out. Newtons laws apply to everything. A wing is more efficient at flying, but anything that can deflect > it's weight in air downward can fly.
Click to expand...

I can think of no better example to illiustrate this than this video documentary of an Israeli F-15 surviving a mid-air collision:

http://www.whoisthemonkey.com/videos/31f15-flying-with-1-wing

Aircraft lost it's entire right wing in the collision. Pilot (not realizing his wing was gone) simply kept flying the plane. It wasn't until after he got out of the cockpit that he saw just how badly the plane had been damaged.

Given enough thrust, anything will fly.
 
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