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First, when calculating force, the unit produced is newtons (N), not kg. You can use kg(force) if you're willing to risk getting confused, and your calculation of the falcon weight shows that you did get confused. In a 1g environment, 1 kg of mass produces 1 kg of force, so there is no multiplication by 9.8. The gravitational attraction between any two ...


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Lift is approximately proportional to velocity squared of the aircraft, not the thrust. That is why runways are required. So the thrust is used the accelerate the aircraft to take-off velocity, which will produce enough lift to overcome gravity. Also, the fact that the thrust is less than the gravity in Antonov implies that it can't do this: ...


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Multi-variable model-predictive process control technology has been around for some time now (at least since the mid 1980's). This means that the number of variables in the control problem is not an insurmountable problem. Assuming that the SpaceX process control engineers have a good intuitive understanding of the theoretical aspects of landing their ...


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Consider what happens if, in your first model, a small meteor collides with the ball after it has been thrown from the craft. It changes the center of gravity of the system but does it affect the motion of the craft? It doesn't because once the ball is ejected from the craft, it no longer has any effect on the craft. It's the force applied to the ball ...


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Depending on your exact definition, I've seen it. An exoatmospheric experiment got messed up when the expended solid fuel engine on the booster continued to expel hot gas and small chunks of motor housing out the back. The added delta-v was more than 1 m/sec, and caused unplanned movement of the booster, which messed up the experiment. It turns out the ...


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If you added up the momentum of all the molecules of gas (vectorially), the combined momentum will be equal in magnitude to that of the rocket, and in the opposite direction. In other words, the velocities of the molecules will be biased away from the rocket.


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Back of the envelope: mean thermal velocity of the molecules or atoms times mass loss rate. At room temperature that may be something on the order of 1000m/s*1e-9kg/s =1e-6N. For a 1000kg spacecraft this amounts to 1e-9m/s^2 acceleration and a position error after a year of about 500km. OK, if you want to land on Mars, maybe you want to correct for that, ...



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