The original Atmospheric Railway dates from 1799.
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Quotefrom: alancalverd on 12/10/2018 09:49:23Using F = GmM/r2 you can calculate the force on a falling object of mass m in terms of M, the mass of the earth, and G, which we assume to be a universal constant.That doesn’t work. We’re trying to compute at least a rough G and M here. We don’t know either of them yet. We do know force F is 9.8 newtons for a 1KG mass. We can assume we know r. We therefore know the product of G and M, but not either separately.
QuoteAs F = ma, we can measure the acceleration of a falling object or the period of a pendulum to get a value for F/m
F=ma works (F 9.8 = 1 (mass) * 9.8 m/sec acceleration), but that doesn’t yield either mass of Earth M nor G, which are the two things we’re trying to determine here.
The pendulum thing is a function of acceleration (9., not of the mass of Earth. Put a pendulum in a rocket accelerating at that rate and it will have the same period as here on Earth. It tells you nothing about the mass of the Earth under you.
A disk-shaped craft is not as subject to side-winds as a slab-side , like an airship or a tube .All aircraft are equally susceptible to crosswind in flight. You fly through a "box of air", and if the box is moving sideways or backwards in relation to your intended track, you have to go faster and change course to compensate. It's not the same as crosswind on the ground, which has the same effect as on a car or boat - you weathercock into wind depending on the shape of the vehicle and the position of its wheels or keel.