Release speed

[ABC2019]

We gravitate around the problem

(2nd edition)

If a Mig takes off with oxidizer and fuel in order to leave Earth to go into space at an altitude of 1000km, why should it exceed the release (or orbit) speed ??

I answered the question, if it has fuel and oxidizer (but in this case it's called a rocket) it doesn't need to exceed the release speed (interplanetary probes never reached 40 km / h).

On the other hand, he needs to take enough fuel / oxidizer to escape the earth's pull, and for a Mig he does not have enough.

The condition on the release speed only exists at the point where you have to cut your motors: there yes, your speed must exceed the release speed at the point where you are (which is root (2GM / r) where r is the distance to the center of the earth.

[gildas]

We gravitate around the problem

(2nd edition)

If a Mig takes off with oxidizer and fuel in order to leave Earth to go into space at an altitude of 1000km, why should it exceed the release (or orbit) speed ??

I answered the question, if it has fuel and oxidizer (but in this case it's called a rocket) it doesn't need to exceed the release speed (interplanetary probes have never reached 40 km / h) .
(...)

Impossible according to Wikipedia, The rocket with the probe will have to reach a speed of 40 km / h to leave Earth ...

Next

What I'm trying to understand:

If a Mig takes off with oxidizer and fuel in order to leave Earth to go into space at an altitude of 1000km, why should it exceed the release (or orbit) speed ??

If he's at Mach1 or Mach 2 or 3, why won't he leave Earth ???
Will it advance more at 40m altitude?

[Obamot]

The orbit of the International Space Station is 400km and you would like a MIG to reach 1'000km altitude

You would have to put too many “ifs” to answer you, already “if” your MIG had tanks big enough to carry enough fuel (which will unfortunately hardly be possible),

Some figures on Space X / Falcon 9 and its ability to put satellites into orbit around the equatorial belt:

How fast does SpaceX rocket go mph?
high-altitude (91 km / 300,000 ft), very-high-velocity (approximately 2.0 km / s; 6,500 km / h; 4,100 mph; Mach 6) ballistic reentry, controlled-deceleration and controlled-descent tests of post-mission ( spent) Falcon 9 booster stages following a subset of Falcon 9 launches that began in 2013.

How fast does Falcon 9 accelerate?
about 5 m / s
At launch, the acceleration is easily calculated. Just divide total thrust by total mass - you can find these on the SpaceX site SpaceX - and subtract 9.81 m / s for Earth gravity pulling down. It comes out at about 5 m / s.

[ABC2019]

We gravitate around the problem

(2nd edition)

If a Mig takes off with oxidizer and fuel in order to leave Earth to go into space at an altitude of 1000km, why should it exceed the release (or orbit) speed ??

I answered the question, if it has fuel and oxidizer (but in this case it's called a rocket) it doesn't need to exceed the release speed (interplanetary probes have never reached 40 km / h) .
(...)

Impossible according to Wikipedia, The rocket with the probe will have to reach a speed of 40 km / h to leave Earth ...

I would be surprised if wikipedia said that, since it is false, do you have a link?

at 1000 km, the distance has increased by about 15%, so the release speed has decreased by about 7% (it's still close to 40 km / s but a little less, in the order of 000) . The further you cut the engines, the less speed you will have to reach to escape. As long as your engines are running you don't have a constraint on speed - just the mass of fuel you carry.

[GuyGadeboisTheBack]

(Tain, I had read: Speed ​​of libation ... )

[gildas]

I answered the question, if it has fuel and oxidizer (but in this case it's called a rocket) it doesn't need to exceed the release speed (interplanetary probes have never reached 40 km / h) .
(...)

Impossible according to Wikipedia, The rocket with the probe will have to reach a speed of 40 km / h to leave Earth ...

I would be surprised if wikipedia said that, since it is false, do you have a link?

(...)

For an object launched from the surface of the Earth, the speed of release allowing it to escape the Earth's attraction is 11,2 km / s (or 40 km / h).

https://fr.wikipedia.org/wiki/Vitesse_d ... 3%A9ration

That's what I'm trying to understand ...

[Ahmed]

Do you want to go out so badly?

[Obamot]

I answered the question, if it has fuel and oxidizer (but in this case it's called a rocket) it doesn't need to exceed the release speed (interplanetary probes have never reached 40 km / h) .
(...)

Impossible according to Wikipedia, The rocket with the probe will have to reach a speed of 40 km / h to leave Earth ...

I would be surprised if wikipedia said that, since it is false, do you have a link?

at 1000 km, the distance has increased by about 15%, so the release speed has decreased by about 7% (it's still close to 40 km / s but a little less, in the order of 000) . The further you cut the engines, the less speed you will have to reach to escape. As long as your engines are running you don't have a constraint on speed - just the mass of fuel you carry.

You're sure? And only the mass of the fuel? What about the payload and the weight of the machine?

Honestly, we don't understand anything about what you write.

The speed of release is a speed of launch. That's all.
Without being too mistaken, it's a speed that depending on the total mass, ALLOWS to stop accelerating afterwards ...
So we CANNOT answer Gildas' question, since to do the calculation you have to have the TOTAL MASS of what he intends to “release” from the earth's attraction!

But I could be wrong it's just that I don't understand what the “funny ones” say

[gildas]

A priori it does not matter the mass of the object to be sent:

The rate of release is a scalar, not a vector quantity: it just specifies an amplitude, not a direction. An object which moves at the speed of release can escape the gravitational field whatever its initial direction (insofar as the trajectory does not meet the surface of the star). It does not depend either on the mass of the object, only on that of the star.

https://fr.wikipedia.org/wiki/Vitesse_d ... 9ristiques

[GuyGadeboisTheBack]

If I understood correctly, once in orbit (28400 km / h) we go fast enough and gravity is weak enough to no longer need only (very?) Little energy to free ourselves from it and go into space *.

* “Space, border of infinity towards which our spaceship, the Enterprise travels. His five-year mission: to explore strange new worlds, discover new lives, other civilizations and, regardless of danger, go where no man has gone before. ”