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This recent question Can a plane bank without turning? asked if a plane can sustain some amount of roll in straight flight, sure they can.

Consider an aerobatic plane (perhaps a Pitts?).

As far as I'm aware it's certainly seems possible for them to fly "on their side" ... roll of 90° or -90° ... at least for short times.

I guess, in a "four point roll" you are on your side (90° or -90°) for at least a short time.

In fact - Pitts owners or others! - how long can you actually do that for?

There would seem to be no (upwards) lift at all?

Are there videos of someone flying on their "side" for miles?

Or in fact is it just an artifact .. you can only actually do it for seconds and really just momentum is keeping you seemingly from losing inches of altitude?

How long can you fly on your side for?

What's the deal on this?

If the answer is "only for a tiny amount of time" in fact, can ALL aircraft do that, or is it really only possible for "aerobatic" aircraft, and if so what's the enabling difference?

Fattie
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  • As a non-pilot (hence comment, not answer), not only can you fly at 90° from horizontal, you can do so as long as you can get fuel to the engine(s). Deflecting the aileron toward the "up" side will cause the plane to adopt a nose-high attitude that gets some of the thrust working against gravity. It also puts the direct airflow against the "down" side of the fuselage which will provide some amount of lift. With enough power directed at the right angle, the engine will overcome the loss of lift from the wings. YMMV based on power to weight ratios. – FreeMan Jul 01 '20 at 15:48
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    The time depends on the fuel system. Normally, aerobatic airplanes have a small tank which supplies fuel in all orientations, but the rest of the tanks only works in upright position. So it is the content of that small aerobatic tank which might be as little as fuel for five minutes. With properly modified main tanks, this might change to hours. – Peter Kämpf Jul 01 '20 at 15:59
  • I remember watching a replica Gee Bee Sportster doing knife-edge climbs. I'm sure it could sustain knife-edge flight as long as its fuel system allows. – Fred Larson Jul 01 '20 at 16:51
  • ah thanks for the dupe link ! – Fattie Jul 01 '20 at 18:08
  • @Pondlife - actually the linked QA does not at all answer the question (unfortunately). (1) it has an irrelevant article about radio planes. (2) there's a link to a video (about what??) which does not work (3) the only answer that actually addresses the question says "Regular airplanes, no. .. No aircraft that I know of can produce enough lift with its component tilted 90°." with no other info or sources :O :O – Fattie Jul 01 '20 at 18:12
  • Can anyone actually tell me if a typical (say) PItts Special can fly at 90° and for how long? – Fattie Jul 01 '20 at 18:13
  • @FreeMan , I completely and obviously understand that, thanks :) It would be as if I asked "what's the world's longest flight" and you said "Anything is possible with fuel". – Fattie Jul 01 '20 at 18:14
  • @FredLarson - there's no such thing as a knife-edge climb. if you start on knife-edge and then turn up, it's no different at all than if you started in any other orientation and then pointed up – Fattie Jul 01 '20 at 18:15
  • @PeterKämpf thanks for the comment. So I roll 90° left. I think what you're saying is the craft then has to yaw (that would be "upwards", now) say, for example, 20°, and it can then proceed in that attitude. That seems like "cheating", the long axis of the craft is not parallel to the ground. – Fattie Jul 01 '20 at 18:18
  • @Fattie: As I recall, he started doing a level knife-edge pass, then kicked a bit more top rudder and started gaining altitude. What would you call that other than a knife-edge climb? – Fred Larson Jul 01 '20 at 18:31
  • heh @FredLarson i get what ytou're saying, and it's incredible he was able to transition from a knife-edge ("merely level") and then turn "right" and be in a straight-up climb. However consider, in the "end" when in a straight up climb (also amazing) that is "just" a straight up climb! no different (no more power needed) than "normally" going in to a stright up climb! – Fattie Jul 01 '20 at 21:43

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