RS007 asked in Science & MathematicsEngineering · 1 decade ago

# can an airplane stand still in the air?

If not, what is the minimum speed? I have an illusion that I noticed a number of times - airplanes literally stand in line wating to land.

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• Anonymous

Only if the plane has engines with sufficient thrust to hold it up against gravity, and it orients itself engines-facing-down to hold itself there -- the most recent jet fighter for the US Air Force can do this, as well as some "jumper jets", but not any other planes and certainly not any commercial airliners can.

Relative to the ground, a plane can be "still" if the wind speed aloft is above the plane's stall speed. In that case, air is moving across the wings of the plane at a fast enough speed to give enough lift to keep the plane aloft even though it doesn't move relative to the ground (the thrust from the engines and the "headwind" balance each other out).

You can get a good sense of this if you fly a lot between the pacific coast of the US and Asia -- the strong jetstream across the pacific does funny things to "ground" speed. When flying west to east (with the jet stream), indicated ground speed on flights I've been on has exceeded 1,000 MPH, even though the plane can't go more than 400 MPH or so with no wind. And flying east to west, indicated air speed will sometimes be as low as 50-60 MPH, even though airspeed is still 400MPH -- that headwind jetstream is a killer, and significantly lengthens the time it takes to get from LA to Tokyo (the normal 11-hour flight once took us 16 hours because of the headwind!) -- though I've made the return trip in under 7 hours!

• 1 decade ago

Aieplanes are specifically designed so that the air drag flowing over the top of the plane actually forces it upwards. As the speed decreases so does the drag and at a complete stop an airplane would literally fall out of the sky.

The best way to understand is to get a spoon and and turn on the tap. hold the spoon (loosely) parallel to the flow of the water (rounded side facing the flow) when you get close enough the water will literally suck the spoon in. It's the same principle for flight.

• Anonymous

that is an illusion but in theory it is possible if the wind speed exceeds the stall speed and you get the correct angle of attack

that was for non-powered or not under power planes - I'm sure you know that Harrier jets and the new tilting-prop planes can hover

and note that you must tie down planes so the wind will not lift them from the ground - the initial portion of that lift is also a hover ( yes it has to be a strong wind but lots of planes have stall speeds of less than 50 mph with almost empty tanks and no cargo - stall speed is the minimum flying speed and it applies when the plane is stationary and the air is moving also )

THIS ALONE would punch a few holes in most of the answers on this page ( sorry lol )

• 1 decade ago

There are way but I may be wrong. For example if you look at a bird for examle a falcon or an eagle, you might see it sometimes hovering over a field. This is because it creates a kind of para-shot shape out of its wings. When the falcon is facing the wing air blows into its wings. The bird is literally able to balance an the air or hover. I could be possible therefore to make a plane that is programmed to use the same tactics a falcon uses. I am only guessing though.

• 1 decade ago

No an air plane cannot stand still in the air. The airplane flies in the air because of upward thrust on wings of the plane because of pressure differance at top and bottom of the wings. This pressure differance is established due to aerodynamic shape of the wing and when plane moves forward at some speed moving air flow creates the thrust. Minimum speed depends upon mass of airplane, shape of aero dynamic wings and size. You can visualise a model toy airplane made of paper can fly at very low speed. while actual airplane may not fly at that speed.

• 4 years ago

Sir: advertisement airplanes could fly at a velocity of roughly a hundred thirty miles according to hour (the main outstanding quantity is particular to the particular airplane) to maintain sufficient left over the airfoil surfaces of the wing and wing roots to maintain the plane aloft. in case you have seen advertisement plane curiously soaring in mid air, i've got self belief that the sight became into an phantasm based upon your perspective of viewing the plane. while an plane is flying very slowly and coming precise at you, or going rapidly far off from you, that's annoying to locate action in a short look. This lack of ability to etect action is greater effective by 0 adjustments in altitude, and greater effective distance from the viewing element. the only advertisement plane i'm attentive to which could easily "hover" in place are particular commuter helicopters that return and forth passengers from one place to a different on short hops. A helicopter can hover in one spot for long sessions of time if desire be because of the fact that the carry required is generated by air omit the rotor blades no longer over definitely plane wings. The wings desire flow in the process the air to advance carry.

• 1 decade ago

It is impossible to have an air plane in still air because there needs to be air flowing under the wings to creat lift. I think that the minimum speed for a boing 747-400 is 155 knots

• 1 decade ago

The only aircraft that I know of that can hover in mid air is the Harrier. I assume your talking about commercial jets though, so no there are no commercial jets that can hover in mid air. If they look like they are then ........well, it's just an optical illusion.

• Anonymous