What happens if a plane nosedives perpendicular to Earth?

In summary, the passengers in a glider would experience weightlessness at the beginning of the flight and then would gradually experience normal weight as the aircraft accelerated towards terminal velocity. In a powered aircraft, the acceleration would increase the normal force of gravity on the passengers.
  • #1
RDS29
2
0
Hi there. I very much enjoy this forum and have been doing so for a while.
I have a problem and I am not sure of the explanation I came with.
Suppose there is a plane that is nosediving perpendicular to Earth. What will the "passengers" feel? In the first seconds the acceleration will be equal with the gravitational acceleration and they will feel wheightless much like in the reduced gravity aircrafts. But what happens after that? The plane will continue to accelerate. Let's ignore the fact that it will reach his terminal velocity for a second. In that period of time in which the plane will continue to accelerate steadily what will happent to the passengers? The constant acceleration will create the sensation of a gravity that acts towards the tail of the plane as stated by the equivalence principle or they will fall faster than the plane because of the lack of drag that the plane gets?
Thank you very much for your time!
 
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  • #3
I am thinking that without drag that the passengers would feel complete weightlessness. When drag becomes a factor the plane will reach terminal velocity. Inside the plane while it is falling with constant terminal velocity the passengers would experience normal weight and gravity. Just like we do while standing on the Earth even though it moves at constant velocity through space.

If the Earth were to accelerate then we would feel a change in weight/gravity.
 
  • #4
jim mcnamara said:
https://en.wikipedia.org/wiki/Reduced-gravity_aircraft

These aircraft provided a repeating near weightless experience for astronaut training.

Thank you. The pilots are flying in parabolas so that the acceleration will be equal to the gravitational acceleration and the weightlessness is felt for only a period of the parabola.

maf249 said:
I am thinking that without drag that the passengers would feel complete weightlessness. When drag becomes a factor the plane will reach terminal velocity. Inside the plane while it is falling with constant terminal velocity the passengers would experience normal weight and gravity. Just like we do while standing on the Earth even though it moves at constant velocity through space.

If the Earth were to accelerate then we would feel a change in weight/gravity.

So you're saying that in the time it takes to achive the terminal velocity they will feel weightless. But due too the orientation of the plane won't it accelerate faster than the gravitational acceleration very soon? Doesn't that have an effect?
 
  • #5
If the Earth were to accelerate then we would feel a change in weight/gravity.

I am not sure if you understand that the Earth as a whole is constantly "experiencing" acceleration, example: it is in orbit around the sun.

From a physics problem set: tuhsphysics.ttsd.k12.or.us/Tutorial/NewIBPS/PS5_3/PS5_3.htm

Assume that the Earth's orbit is a circle* of radius 1.50 x 1011 m. The period which the Earth orbits around the Sun is: 31558464 seconds. The centripetal acceleration of the Earth in its orbit around the sun will be: a = v2/r = (2πr/T)2/r = 4π2r/T2.

*the orbit is really an ellipse. The number of seconds in the example is therefore off by a small number.
 
  • #6
RDS29 said:
Suppose there is a plane that is nose diving perpendicular to Earth. What will the "passengers" feel? In the first seconds the acceleration will be equal with the gravitational acceleration and they will feel wheightless much like in the reduced gravity aircrafts. But what happens after that?

It depends on the aircraft.

In a glider it's as you said. You would initially feel nearly weightless. Then, if it were to approach terminal velocity you would no longer be accelerating and would experience 1g in the downward direction.

The constant acceleration will create the sensation of a gravity that acts towards the tail of the plane as stated by the equivalence principle...

Correct. In a powered aircraft it would depend on how long the aircraft could continue to accelerate downwards and what that rate of acceleration was. The normal acceleration due to gravity is 9.8m/s/s. If the aircraft were to accelerate downwards at around twice that, say 19.62m/s/s then you would feel a net 1g upwards. If the aircraft had a suitable room inside you could walk upside down on the ceiling. The problem is that an aircraft cannot accelerate downwards indefinitely. Typically they have a VNE (Velocity Never Exceed) limit beyond which the forces on the aircraft become too large.

I used to fly gliders and did some 3 or 4g aerobatics in single engine aircraft back in the 1970's. Great fun if you ever get the chance.
 
  • #7
RDS29 said:
So you're saying that in the time it takes to achive the terminal velocity they will feel weightless.
There is no such time. Speed and drag will increase slowly over time. If the aircraft does not use its engines, apparent gravity felt by the passengers will slowly increase from 0 to 1g while the aircraft gets closer to its terminal velocity. In an idealized world, the aircraft never reaches this velocity, but in practice it gets so close that the difference gets negligible.

If the aircraft uses its engines, then apparent gravity can point upwards initially.
 
  • #8
Negative g force is something fighter pilots routinely encounter and train to withstand.

And here's how to use it to levitate a cell phone
 
  • #9
jim mcnamara said:
I am not sure if you understand that the Earth as a whole is constantly "experiencing" acceleration, example: it is in orbit around the sun.

I do know that but It wouldn't have helped answer the question. It was just for the purpose of explaining that you could be traveling at a high speed and experience no change in weight.

yes there is radial acceleration but it's small compared to the acceleration of gravity. Otherwise we would experience different weights at different times of the year and also a difference between day and night.
 

Related to What happens if a plane nosedives perpendicular to Earth?

1. What causes a plane to nosedive perpendicular to Earth?

A plane can nosedive perpendicular to Earth due to a variety of factors, such as mechanical failure, pilot error, or extreme weather conditions.

2. What happens to the passengers and crew on a plane during a nosedive?

During a nosedive, passengers and crew will experience a sudden drop in altitude and increased acceleration. This can cause them to feel weightless and may lead to injuries if they are not properly secured in their seats.

3. Can a plane survive a nosedive perpendicular to Earth?

It is unlikely that a plane could survive a nosedive perpendicular to Earth due to the extreme forces and stress placed on the aircraft. However, some modern planes are equipped with advanced safety features that may increase the chances of survival.

4. How do pilots try to recover from a nosedive?

If a plane begins to nosedive, pilots will try to regain control by pulling up on the control column and increasing engine power. They may also use other emergency procedures, such as deploying spoilers or flaps, to reduce the speed and increase lift.

5. Has a plane ever nosedived perpendicular to Earth and survived?

There have been rare instances where a plane has survived a nosedive perpendicular to Earth, but these are extremely uncommon and often involve skilled pilots and some luck. In most cases, a nosedive of this nature would result in a catastrophic crash.

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