uhntissbaby111
Topic Author
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Joined: Tue Feb 03, 2009 8:05 pm

### Can You Maintain Altitude At A 90 Degree Bank?

Me and my roommates just got into an argument about whether a plane can maintain altitude while in a 90 degree bank? I dont think the plane could because there would be no vertical component of lift to keep the plane at a constant altitude. But then i confused myself and realized, that you could use rudder to keep the nose up and use the vertical component of thrust to keep the plane up? Also, the main plane we talked about was an F-16. So, could an F-16 do it? And if not, can any plane do it?

EA772LR
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting Uhntissbaby111 (Thread starter):Also, the main plane we talked about was an F-16. So, could an F-16 do it? And if not, can any plane do it?

I don't believe so because the like you side nearly all lifting devises lose lift at 90 degrees. Can stay at altitude briefly, bu I don't think you can maintain altitude for very long. Have you ever scene a plane at an airshow stay on it's side for very long? As in extended periods of time, not just in a hard bank? I mean flying a straight path on it's side and maintaining it for long.

[Edited 2009-06-16 12:25:37]
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vikkyvik
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting Uhntissbaby111 (Thread starter):Me and my roommates just got into an argument about whether a plane can maintain altitude while in a 90 degree bank? I dont think the plane could because there would be no vertical component of lift to keep the plane at a constant altitude. But then i confused myself and realized, that you could use rudder to keep the nose up and use the vertical component of thrust to keep the plane up? Also, the main plane we talked about was an F-16. So, could an F-16 do it? And if not, can any plane do it?

Yes, an F-16 theoretically could, because it has a thrust-to-weight ratio greater than 1.

That thrust, plus whatever lift the fuselage might give you in a 90-degree bank, probably allows it to do so. You sure do see them do plenty of 90-degree-bank turns at air shows and such.
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DaBuzzard
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

High performance aircraft (like fighters or acrobatic specials) certainly can maintain altitude in knife edge flight. Don't think I would want to try it with a 172....or a 747

Excess thrust plus the lift from the side of the fuselage and the vertical (now horizontal) stab will do the trick.

This of course is all dependant on the fuel system being able to keep the engines fed.....

[Edited 2009-06-16 13:00:09]

zotan
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

It's definitely possible. The rudder more or less acts as the elevator.

airbuske
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

Come on guys, I thought we are supposed to be aviation enthusiasts?

I suggest you look up some performances by the Blue Angels. They routinely perform knife edge passes.

ZBBYLW
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

Yes it is very possible. Even a super decathlon can maintain level flight at 90 degrees. All you do is put it on it's side and have the nose high relative to the tail.
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EA772LR
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting ZBBYLW (Reply 6):Yes it is very possible. Even a super decathlon can maintain level flight at 90 degrees. All you do is put it on it's side and have the nose high relative to the tail.

I stand corrected in my initial post. That is interesting.
We often judge others by their actions, but ourselves by our intentions.

Pellegrine
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

Don't try it in a B-52......
oh boy, here we go!!!

brons2
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting Pellegrine (Reply 8):Don't try it in a B-52......

with very slow airspeed and close to the ground...
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Fly2HMO
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting Uhntissbaby111 (Thread starter):So, could an F-16 do it?

The Thunderbirds do it every time in their airshow performances.

 Quoting Vikkyvik (Reply 2):Yes, an F-16 theoretically could, because it has a thrust-to-weight ratio greater than 1.

That would have nothing to do with it if the thrust is still being put out on a horizontal vector. It just has enough rudder authority and speed to do so.

While a C172 has barely any rudder movement/authority, If you could get it to fly fast enough eventually theoretically the lift vector created by the rudder would be sufficient to keep it in level flight.

 Quoting ZBBYLW (Reply 6):Even a super decathlon can maintain level flight at 90 degrees.

Yup. Been there done that. The Decat has a huge and very powerful rudder. On a good day you can get it to climb in knife-edge.

 Quoting Brons2 (Reply 9):with very slow airspeed and close to the ground...

and lots of fuel...

[Edited 2009-06-17 12:00:01]

Jetlagged
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting FLY2HMO (Reply 10):That would have nothing to do with it if the thrust is still being put out on a horizontal vector. It just has enough rudder authority and speed to do so. While a C172 has barely any rudder movement/authority, If you could get it to fly fast enough eventually theoretically the lift vector created by the rudder would be sufficient to keep it in level flight.

I assume you mean that the rudder creates a yaw angle which in turn creates fuselage lift (i.e. sideforce). The rudder has to produce downward force to generate the yaw angle, so is reducing lift. Engine thrust tilted down by the yaw adds to the lift. Rudder authority is important to create the necessary yaw angle to create fuselage lift.
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wingscrubber
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

I believe the term is 'knife edge', I've seen pitts specials and extras do it at airshows, also they have to briefly knife edge between the pylons in the red bull air races.
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Fly2HMO
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting Jetlagged (Reply 11): I assume you mean that the rudder creates a yaw angle which in turn creates fuselage lift (i.e. sideforce).

Yeah that's what I was going for. Thanks for polishing my statement.

By the way, the GeeBee was capable of flying in knife edge with barely any rudder input whatsoever, which is understandable since it had more fuselage area than wing area.

http://en.wikipedia.org/wiki/Gee_Bee_R-1

[Edited 2009-06-17 13:05:55]

2H4
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting FLY2HMO (Reply 13):By the way, the GeeBee was capable of flying in knife edge with barely any rudder input whatsoever, which is understandable since it had more fuselage area than wing area.

Also, the GeeBee was more stable inverted than it was when flying right side up.

Delmar Benjamin's announcer spoke of this as though it was something to be proud of, but I think most would consider it a not-insignificant design flaw.

2H4
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Fly2HMO
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### RE: Can You Maintain Altitude At A 90 Degree Bank?

 Quoting 2H4 (Reply 14):Also, the GeeBee was more stable inverted than it was when flying right side up.

Hmm I actually didn't know that, but taking a second look at it now it makes sense, those wings are really low and the fuselage pretty tall, guess the CG must be high up there.

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