Still on the ice gun, I'm considering the thrust and time-of-acceleration.
The chassis is a ramjet. Those travel between a minimum and a maximum velocity dependent upon airflow. NASA Ames promised final velocity - at the direction of the barrel - 8 km/s. The ice gun will be launching at an angle (New Guinea promises some mountains steep enough and uninhabited) to break atmo.
8 km/s even vertical won't beat escape velocity at 11.2 km/s. Per Erk Inger, "Mass Driver Design Traveling Earth to the Moon" (2019): it doesn't have to; 8 km/s can defeat atmospheric drag to enter a 185 km orbit. At least, energy-wise it can; once the craft is there, something must push this into LEO. NASA recommended carrying some sort of gyro, and using that in space.
As to thrust, NASA thought they could accelerate their jet over 1000 km. From zero to cover that with a steady acceleration this is GCSE Physics (or tenth-grade calculus), a t2 / 2 = 1000. As to that acceleration this is 8/t. So 8 t / 2 = 1000; t=250 s. a is then 8000 m/s / 250 = 32 m/s2 tangent. By Pythagoras the passengers will feel 33.5 m/s2 which is 3.4 G. G-LOC doesn't hit 'til 5.4 G so, most of us can withstand it.
[I'm leaving aside, for this poast's sake, what "zero" means for ramjets.]
Pity 1000 km ain't gonna happen. Their 100 km alternative settled for 4.4 km/s. 4.4 t / 2 = 100 means 45.45 s, 96.8 m/s2 so 97.3 m/s2 which is, yes, approaching 10 G. Also this is a literal toss-up: it will need assistance to orbit-speed.
In theory the maths check out. It's just that 200 km is pushing the limit of what we can do with Antarctic ice, 4.4 km/s pushes the limit of a useful earth-to-orbit trajectory, and 5.4 G pushes the limit of human endurance.
BACKDATE 5/14
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