the poster above was very conservative in his metrics and throtteling requirements.
Modern pressure vessels can reach 5% empty mass, thats a factor of 20
Rockets have stages, a good approximate is to stage half your rocket to get rid of the most empty mass. This also means your first stage has to have double the thrust to lift itself and its stage. Now you're at a factor of 40 just to hover.
Now you actually have to take off, usually around 1.2 to 1.4 thrust to weight.
So a more realistic scenario means your rocket engine has to throttle down to exactly 2% power while the laval nozzle is optimised for takeoff thrust only.
Modern pressure vessels can reach 5% empty mass, thats a factor of 20
Rockets have stages, a good approximate is to stage half your rocket to get rid of the most empty mass. This also means your first stage has to have double the thrust to lift itself and its stage. Now you're at a factor of 40 just to hover.
Now you actually have to take off, usually around 1.2 to 1.4 thrust to weight.
So a more realistic scenario means your rocket engine has to throttle down to exactly 2% power while the laval nozzle is optimised for takeoff thrust only.