Can You Help Me Win This Bet About Airplanes?

Question

I work near an airport and when I am driving home in the early evenings I sometimes see a plane in the air with their landing gear down and they are NOT MOVING.

It is like they are hovering. I guess they are waiting for permission to land. They don't stay motionless for long but they are motionless.

I told my boyfriend about this and he said airplanes cannot stand still in the air like helicopters. He said they are still moving but it is so fast it looks like they are standing still (which I do not believe).

Anyway, we have a bet and the loser takes the winner to dinner.

So I ask you, I say an airplaine can stand still while in the air for at least a few minutes. I am talking about a regular passenger airplane.

Am I right?

Answer 1

In a practical sense, no, it is not possible for a passenger airplane to hover.

Airplanes must maintain a certain equilibrium to stay airborne. There are four forces acting on an airplane; thrust, drag, lift, and weight. To counter the weight of the airplane, a certain amount of lift must be maintained by the airplanes various airfoils (or, wings, simply put).

Wings use something called Bernoulli's principal. Basically, the wing is shaped so that the air contacting the wing head on must travel faster over the top of the wing, as its curvature makes the distance longer than the air traveling under the relatively flat bottom. The greater pressure on the bottom wing, and the reduced pressure on the top of the wing causes an upward force called lift.

Simply put, if there is not a relative wind passing over the airfoil, the airfoil is not producing any lift. Since the force of lift counters the force of weight, and there isn't any lift without air flowing over the wing, there is nothing to support the immense weight of the airplane.

Some airplanes, however, use thrust as a way to "hover," or takeoff vertically, such as a helicopter. Some examples are the new F-35 Lightning II, or the AV-8 Harrier, which utilize thrust nozzels aimed at various angles to the ground to counter the weight with pure thrust. However, commercial airliners or smaller commuter and executive planes do not utilize this. Unless you're looking at one of these airplanes, which is unlikely given the size, the airplane is not hovering.

I live near an Air Force base, and I have seen what you are talking about before. C-130s and other slow flying aircraft do appear to be almost motionless in the air, but rest assured, they are moving, and moving a lot faster than you probably realize. I do not know exactly what may cause this, but it could be the lack of positive references in the sky. You can easily identify the movement of a car based on the objects around it. However, in a perfectly clear sky, it may be hard to reference an airplane that is moving slowly.

Answer 2

no. no way.

it is just an illusion due to the lack of visual refferences to compare the relative speed with.

Answer 3

Some planes can hover. But, for the purpose of this argument, You're wrong... Sorry.

Answer 4

No, they cannot under normal flight conditions. Theoretically if there was very, very high head winds they could, but with winds that high they'd never fly into the area in the first place. Some of the small ultralights can hover, simply because their stall speed is so low they can encounter winds fast enough to stay airborne without moving forward.

But the impression you got was probably more about distance, than speed. The airplane was probably much larger than you think, so the distance it covered may have appeared much smaller. And if it was landing into a very strong wind, it would have been moving slower than you are used to.

Answer 5

You're wrong, he's right. You lost.

But his explanation of them being so fast they appear motionless is not correct.

Answer 6

Certainly airplanes can "hover".

I remember the days of flying a Cessna 152 about 3000 ft offshore.  One flight session, my instructor and I in the 152 ended up "hovering" over the coastline while I was practicing my slow flight facing a strong headwind. So yes, technically, it is possible for airplanes to hover given the right condition, since you didn't mention the airplane in question was flying in still air.

Answer 7

hahaha your totally wrong i know what you were doing u were going in the opposite way of the airplane so it appeared like it was hovering when it was actually moving next time u see an airplane look at the way its going then start walking the opposite way you'll see what u were doing ha ha nice try tho...there is an airplane that can hover but its an army airplane and you'll never see this flying out of an airport near u anytime soon

Answer 8

Regular airplanes cannot stay in the air unless they are moving forward.  If they stop moving forward they fall out of the sky, simple as that.

Answer 9

Absolutely not.  All fixed wing aircraft need to maintain a certain speed in order to stay in the air.

Answer 10

There is one way that a commercial airliner can "hover" and that is if the wind speed is equal and opposite to the plane's airspeed (similar to the scenario of throwing a ball 50 mph into a 50 mph headwind). That being said it would have to be at least a 100 knot headwind which is entirely unlikely near the ground.

However you boyfriend is not entirely right either, it is not the fact that they are moving quickly that makes them look slow, but rather the relative motion. The further the object is away the slower it appears to move. Wave your hand right in front of your face and it seems to move fast, have some one wave to you from a mile away and it looks like their hand is barely moving. When observing aircraft this is intensified by the fact that you have no reliable reference points in the sky.

Answer 11

If the plane was a Harrier or an Osprey, they can hover:

http://en.wikipedia.org/wiki/Harrier_%28...

http://en.wikipedia.org/wiki/V-22_Osprey

But you would need to be near a military airfield to see one of those.

Answer 12

I suggest you offer to make dinner for him.... make something really nice, because you're really wrong.

Answer 13

You lost the bet.

Answer 14

I'm sorry, but ordinary airplanes with wings cannot stand still in the air, but must keep moving forward to stay aloft.  If an airplane is holding for a landing clearance, it will be flying a predetermined loop in the air called a "holding pattern."

Sometimes you can get the impression that an airplane is stationary because it is moving straight toward or away from you and the angle of view does not seem to change from moment to moment, or bacause the distances involved make it seem to be taking "forever" for motion to appear evident.  But it is moving, even though it doesn't appear to be.

So the dinner is on you.  Sorry.

He is wrong about one thing.  The illusion is not because they are moving fast, but because they are moving slowly.

The thing for you to do is take flying lessons and get your Private Pilot Certificate; then you will know much more about it than he does, and you can take him for rides and show off your skills!  Then he can pay for dinner.

--Have fun...(!)

Answer 15

The answer is no a plane cannot hover..it has to be moving some kind of way in order to stay in flight. Easiest way to understand would be to downscale your thoughts back. Think of the 1$ balsa wood glider you can build...or even a paper airplane...you throw it...it flies...you drop it falls straight down...a passanger airplane would drop straight downward if it tried to hover...but it sometime does look like they are.

Answer 16

its impossible for a plane to be motionless. I was near LHR (London Heathrow) and saw a plane descending on final approach to land and it 'seemed' that the plane was falling so slowly it was almost like it hovered

Answer 17

Get your wallet out. It is aerodynamically impossible for a fixed wing jet airliner to hover. Most must keep above 150 Kts to even stay airborne. If you drop below stall speed the aircraft loses lift and stalls. If you look at an airplane while landing at a certain angle it will appear to be motionless, but it is not.

While there are jet fighter aircraft that hover using a directed fan arrangement that diverts the jet exhaust downward, there is no such airliner.