2007-03-20 05:33:21 · 14 answers · asked by Subash B 1 in Cars & Transportation ➔ Aircraft
An airplane flies due to the air passing over and under the wings. The pressure differences between the air on the top and air on the bottom create Lift, which allows an airplane to stay in the air. If an airplane gets too slow, it will stall. Stalling is when the air is no longer going fast enough at the right angle to provide enough lift to keep the airplane in the air. There are lots of complex equations and principles involved, but that's the upshot. A helicopter can hover because the rotor is essentially a wing that is being spun around to provide the lift. In fact, there are some airplanes that can hover, such as the Harrier, but they hover by redirecting the engine power straight down. You can read more about how airplanes work at http://www.howstuffworks.com/airplane.htm
2007-03-20 05:43:36 · answer #1 · answered by Scott H 3 · 0⤊ 0⤋
airplanes fly, by and large, the same way. Sure there are some exceptions but for simplicity sake lets just leave those out.
They fly by having wings, and by moving those wings through the air very fast. Due to the shape of the wing the airflow over the wing is a little bit faster than the flow under the wing. According to Bernounlli's principle, a fluid ( gas included ) moving has less pressure than a fluid not moving. the faster it moves the less pressure it exerts. So what you end up with is a vaccuum over the wings that sucks them upwards. If the wings do not have enough airflow over them, they produce no lift and the plane will not fly. So there is no way for a plane to hover unless you could somehow blow air over the wings at 150mph or so.
the exceptions:
Some jets can take off and hover, but they do this not by creating lift, but through what is basically brute force. They can aim thier jet engines downward and through sheer thrust, push the airplane up into the air. The Harrier is one such jet that can do this.
2007-03-20 12:40:32 · answer #2 · answered by Louis G 6 · 0⤊ 0⤋
Airplanes are lifted into the air by a difference in air pressure above and below the wings. This difference is created by the shape of the wing affecting the air as it moves over the wing. Without this air movement, the airplane would have no lift, and would fall like the 50 ton lump of metal that it is. In theory, when flying into a strong headwind, an airplane could hover if the wind speed, coming from directly in front, equaled the flying speed of the aircraft - this is why they measure airspeed (the speed of aircraft in relation to the speed of the air), and not distance flown over time.
2007-03-20 12:49:41 · answer #3 · answered by Me 6 · 0⤊ 0⤋
It is not a convenient way to get from one place to another. It might be possible to get up in the jet stream in the 150-200 mph range and stop in midair, or maybe even go backwards, but what practical purpose would it serve, other than to show it can be done.
I have done it in Cessna 152 at 5000 feet in high wind just to show it could be done, and there was no other useful purpose for the maneuver.
2007-03-21 22:20:35 · answer #4 · answered by eferrell01 7 · 0⤊ 0⤋
there is a jet that can hover and it is called the AV-8 Harrier and it has jump jets on it so it can hover. Also they cant hover because they need constant trust on the engines and the engines are parellel to the ground so it will go forward is it is going verticaly it will hover.
2007-03-23 22:28:06 · answer #5 · answered by STOKES A 1 · 0⤊ 0⤋
It can. During WW2 when the B-29's first met the jet stream [unknown until that time ]high over Japan, they not only stood still they were in some cases pushed backwards.
2007-03-20 14:21:13 · answer #6 · answered by Anonymous · 1⤊ 0⤋
Because they fly due to the Bernoulli effect and that requires air moving over the wing. You could always try a V22 Osprey kind of approach but then your 747 would require about 1,000,000 pounds of thrust instead of the 200,000 it takes to fly normally.
2007-03-20 12:50:14 · answer #7 · answered by Chris H 6 · 0⤊ 0⤋
two types of aircraft. fixed wing and non-fixed. airplanes fall in the fixed wing category which is where a stationary wing forces it to keep moving.
VTOL (Vertical Take-Off and Landing) aircraft are the only exception to this
helicopters and auto-gyros can hover because they have more moving wings than they do stationary.
2007-03-20 17:53:59 · answer #8 · answered by free2sail34 2 · 0⤊ 0⤋
they do have jets that hovers in the air
2007-03-20 16:25:00 · answer #9 · answered by master t 1 · 0⤊ 0⤋
first, it wouldn't be practical given there size. Secodly, the engines don't rotate into a position where that would be feasible. I would also venture to say that cost and safety is a factor too.
2007-03-20 15:53:13 · answer #10 · answered by evil_paul 4 · 0⤊ 0⤋