2 ms·
The delta-V is around 16km/s. For high-efficiency chemical propulsion (e.g. hydrogen - which, note, non-storable!) that's about 3.5-4x the exhaust velocity, me
by azernik 5y ago
The delta-V is around 16km/s.
For high-efficiency chemical propulsion (e.g. hydrogen - which, note, non-storable!) that's about 3.5-4x the exhaust velocity, meaning around 98-99% of your spacecraft's mass needs to be fuel.
For electric propulsion (which has issues because of low thrust and electrical power requirements), it's only about 0.5-1x the exhaust velocity, so only maybe 50-70% of spacecraft mass needs to be fuel.
In any case, it's a LOT.
- MichaelZuo 5y agoAh thanks, Project Orion makes a lot more sense in that context!
- azernik 5y agoYeah, people tend to pretty easily understand how the rocket equation is exponential in the required ∆V, but the way it's inversely exponential in exhaust velocity is less well understood. Good specific impulse plus good thrust is a combo that requires nuclear-explosion-scale energy, ie Project Orion or Nuclear Salt Water Rockets (an option that is, shockingly, even more insane than Orion).