I have been told that u can stall a plane no matter how fast u go. How do planes acheive a loop the loop then?

Question

This was another question i asked and was confused by the answer.

Can you help?

http://uk.answers.yahoo.com/question/index;_ylt=Amdq52cD5Cx6DVb6spXRfDchBgx.;_ylv=3?qid=20080330135539AAyAcaQ

Answer 1

The maneuver is simply called a "loop."

"Stall," in an airplane, refers to the wing, rather than the engine.

Most airplanes can be stalled at any structural speed by making excessively abrupt maneuvers or excessive bank angles.  Nobody's fool told you that.

In a loop, all but the most powerful airplanes will be in a stalled configuration for part of the loop.  The loop continues because of inertia and control forces.

Answer 2

Aircraft pulling out of a dives sometimes stall at a very high speed.

The angle of attack is not the deck or longitudinal angle.  It is not the angle of the flight path.

Answer 3

Every airfoil has a certain angle of attack, which when exceeded, will result in a stall.  An airfoil may stall at ANY airspeed and at ANY attitude.  

  An aircraft can execute an aerobatic maneuver like a loop as long as the limiting angle of attack is not exceeded.  In practical terms: one must increase airspeed enough to achieve a controlled loop.

Answer 4

Hi Paul -

If you are flying straight and level, the wing is at a steady but small angle of attack - one that will generate enough lift to just balance the weight of the aircraft. If you pull back on the stick, the elevators will cause a net increase in angle of attack on the wings, resulting in more lift. This will cause the plane to rise - nose up. By continuing to hold back pressure on the stick, the wings will continue to push the nose "upward" until it passes vertical, then inverted, vertical nose down, and finally back to level flight. At that time, you should trim out for level flight again or you will keep looping.

A stall can occur at any speed, once the angle of attack reaches the critical point. At supersonic speeds, stalls take place a little differently, but I don't think that's what you are referring to.

The back pressure on the stick varies a bit during a loop, because as you point the nose upward, the airspeed bleeds off, which results in different control inputs to maintain the maneuver smoothly. As I recall, we used to enter a loop with full mil throttle in a T-38 with the nose about 30 deg low and an airspeed over 400 knots. Then we would pull hard and get down to about 250 knots at the top of the loop, where the stick pressure had to stay light to avoid stall. On the back side, headed straight down, we would pick up airspeed quickly, and we had to pull about 4 - 5 G to keep the speed from exceeding 450 knots at the bottom. It was interesting, but we had to stay focused to avoid going supersonic on the way down..

Answer 5

Or perhaps a high speed stall?

Answer 6

yeah its called a speed stall

Answer 7

Not only can an airplane stall at any airspeed, but also in any ‘attitude’.  By that I mean that the wing can stall while flying vertical lines (up or down) or while flying inverted, or any other direction.  The stall can be from positive or negative attitude changes.  One wing can stall while the other wing continues to generate lift.  

In aerobatic airplanes during competition, there is simply enough ‘energy’ to perform a loop without exceeding the angle of attack where a stall occurs.  This energy is a combination of engine power and airspeed.  In, say, a Pitts (most models), you have enough power to perform a loop from level ‘cruise speed’ flight while pulling no more than about 4 – 5 G’s.  The wing will NOT be stalled at any point in the loop – and at the top of the loop, you are somewhere around the minimum G loading of .5 G’s and about 80 MPH.  The wing generates lift during the entire loop.

Answer 8

A stall occurs when the air flow over the wing ceases to flow steadily and breaks away from the surface. This results in a sudden loss of lift. Causes may be a combination of low air speed and nose-up angle, or it can happen as the speed goes supersonic. An extreme example of a recoverable stall is the "Snake Bite" manoeuver preformed by the Russian MIG Foxbat aircraft. Vintage aircraft used to land effectively stalling onto the ground to make a 3 point landing. Modern aircraft with nose wheels land at a higher speed for safety reasons. In the recent loss of power incident at Heathrow the pilot was bringing the airliner down balancing the need to extend flight range against the possibility of stalling and crashing short.

Answer 9

The angle of attack is between the Relative Wind (the vector of the wind passing over the wing) and the chord line (the longest line between the leading and trailing edge).

You can stall at any speed if you are demanding something from the wing (lift) by increasing or holding back pressure (up elevator).  You can't stall, no matter how slow you are going, if you aren't demanding anything.  Bank angle helps here, it's called an accelerated stall.

A loop or any other manuver is achieved because the critical angle of attack (see the other answer) is not reached with the speed at the time.

For example, if you tried to loop a T-6, normal entry speed is 180.  I've done it as slow as 140, but you can't pull very hard and have to float over the top.  This takes less than the normal 3g entry.  However, even if you are faster than 180 and snatch the stick back to 4g or more, you will feel the beginning of a stall.

Hope this helped.

Answer 10

Basically it is the same as a car isn't it....the engine stops. Something to do with when an aircraft climbs....gets to a certain point........actually not really sure I know now.

Answer 11

yes, a good example of this is when you try to pull out of a steep dive. You will be going very fast but if you pull out too abruptly you lose the airflow over the wing which is a stall, so you could crash. This happens.

Answer 12

When a plane does a loop it is able to maintain enough speed to keep air flowing. In a stall, speed is lost until the engine cannot operate.