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Do airplanes lose stability when at 0 mph? ?

When an aircraft is put into a complete stall, 0 mph let's say by putting it into a vertical climb then shutting off the engine.

Is it normal for the aircraft to "tumble" ? To spin out of control until enough air flow has been achieved to regain aerodynamic stability?

Update:

One of the first Constellations "Connie's" Howard Hughe's piloted had reportedly reached an airspeed of zero when he deployed full flaps while in flight.

Of course if the aircraft is capable of predictable flight it is assumed that it is either a) positively and aerodynamically balanced or b) it is computer guided so it would be a given to assume that the aircraft would pitch downwards.

My aircraft is unique, it features no vertical stabilizers and it is a flying wing, it relies on the dihedral in the center, as well as the 2 degree washout and the 30 degree sweep to keep it flying straight hence "Gull Wing Flying Wing" not sure if I mentioned that.

So when I engaged the flaps and put it into an exponential climb from full speed level flight, then shut off the motor at an altitude of say 300' ( yes it is a model airplane ) sometimes one of the wings will lead the other and almost enter a flat spin though the design is resistant to spinning.

I then

Update 2:

I should have been more precise, by stall I did not mean loss of airflow over the wings, though technically it is but what I meant was this aircraft has a power rating of about 200 watts / lb which in the rc world is a rocket, so it's thrust exceeds the weight of the aircraft.

So when the aircraft is climbing vertically, then suddenly stops, the aircraft no longer has any forces acting on it as others have said, except gravity. I was just curious if an aircraft should be stable even in such circumstances, perhaps it is a dumb question.

I remember watching the intro of the movie "Space Cowboys" and although it is a movie, this film does depict the rapid loss of control when losing speed and put into a situation where it can be induced to spin.

7 Answers

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  • 8 years ago
    Favorite Answer

    Some of the other people answered this pretty well already -

    Commercial jet aircraft would never get to 0mph first of all and you would never get them to climb completely vertically.

    Even in a stalled condition they would still have some forward speed, but a stall occurs when the angle between the airflow and the wing is so great that the wing no longer flows smoothly over the wing, ut breaks up - this stops the wing producing lift and it stalls.

    When a wing stalls it is still producing some lift but not enough for the airplane to stay aloft so the wing will drop and the aircraft will also yaw. If at the point of stall you also kicked in some rudder this causes more of a yawing motion and the airplane goes into a spin where the nose is turning and the wings are effectively lifting, stalling, dropping. It is possible to get of this condition by lowering the nose, using opposite rudder to prevent further spin and as the aircraft now descends nose down the airflow increases over the wing again and they install.

    The reason you couldn't get a normal commercial aircraft completely vertical is that the stabiliser at the back (the horizontal flat part of the tail) would not have enough authority - it is basically a wing as well and it too would stall.

    Military jet aircraft which reach complete vertical positions do so through engine power more than anything else.

    Large jet aircraft do not do so well in stalled conditions. They can enter something called a 'deep stall' This is when the wings and tail are both stalled. The aircraft is usually in a flat spin at this point and the pilot has no aileron or stabiliser authority - they are stalled and don't work anymore. The only control with any authority is the rudder but it is not always enough to get out of the stalled condition - because the tail is completely stalled the pilot cannot change the pitch of the aircraft to unstall it. Using the rudder may help or may send it into a spin which on large aircraft could break the controls and rip it apart rather than help unstall it.

    http://en.wikipedia.org/wiki/Stall_(flight)#Deep_s...

    Small, light aircraft and aerobatic aircraft can spin and often do so at air shows. Likewise military aircraft often demonstrate tumbles by climbing vertically and then allowing the nose to roll over and drop and they tumble down until power is applied again and they climb out. Military fast jets are not the same aerodynamically as other aircraft though and often use engine power to climb etc rather than wing lift so much.

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  • FanMan
    Lv 5
    8 years ago

    Stability is a function of the aircraft's aerodynamics; at zero airspeed the stability is undefined or neutral. No, it's not likely to spin or tumble, but you will have no control (not the same thing as stability) until speed, and thus airflow over the control surfaces, has been regained.

    It's also very difficult to get an aircraft down to zero airspeed, unless you do a tailslide from a vertical climb. Normally, as soon as you get below the stall speed, the nose will drop, and the aircraft will immediately resume flying speed.

    Casper, very few aerobatic aircraft (other than R/C models) have enough power to hang on their propellers.

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  • 8 years ago

    Fixed-wing aircraft must move continually through the air around them in order to remain aloft, so an airspeed of zero is not a stable or maintainable state for the aircraft.

    Aircraft that enter a stall are not necessarily moving at zero airspeed. Stalls can occur at any speed. The only thing required for a stall is an excessive angle of attack.

    No, it is not normal for the aircraft to tumble. After a stall, even at zero airspeed, the aircraft will generally assume a nose-down attitude and drop until the angle of attack of the wings drops below the stall angle again, which typically takes only a second or two. Some aircraft can enter a spin if they stall at very low airspeed under the right conditions, but it's not the usual consequence of a stall. Stalls at higher airspeeds are even more unlikely to produce a spin.

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  • 8 years ago

    It's not normal to tumble. Most airplanes will do a tail slide when they reach zero airspeed in a vertical climb. You need to force it to begin tumbling before it reaches zero airspeed if that's what you want it to do.

    There is no stability at zero airspeed. That could also be called neutral stability; not stable, not unstable.

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  • one of principal aerobatic figures is a propeller hover.

    ALL aerobatic performance planes are capable of "hovering" or hanging on their propeller. as such, the airplane has zero speed, undefined angle of attack, and is completely stable. due to the prop wash, the pilot can pitch down to increase the airspeed again, and renew the lift.

    @dusty rhodes.. you probably never ever heard of MOMENTUM.. there are stunt planes that climb TAIL first, trading momentum for altitude.

    Source(s): put enough thrust on it and a barn door will fly. when in doubt, put TWO engines on it and even a Phantom willl fly
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  • 8 years ago

    Stability by definition implies two or more forces being balanced. In the case of an airplane with zero aerodynamic speed and no propulsion, the only force that remains is gravity. You cannot balance a single force, and therefore stability has no meaning.

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  • Derail
    Lv 7
    8 years ago

    You kinda answered your own question here. If the plane had gone into a stall, then yes that means with out air flowing over the wing surfaces, the plane will cease to fly.

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