Hippy-friendly hybrid-electric rocket motors
I'm still boggling at the use of electric turbopumps on the Rocket Lab's Electron, but if you only need 1 megawatt (those 9 engines are tiny) for about 2 minutes then that's about 33kWh and not too bad.
The engineering and development advantages are interesting. You entirely eliminate all the turbomachinery of the fuel pumps, so that makes development easier. You're not diverting propellant to run turbines, so the engine can gain efficiency without the plumbing complications of a staged combustion engine.
The drawback is a heavy battery pack, but it'll be lighter than an electric car's because you don't care about reusability and good recharging characteristics.
I wonder how electric pumps would scale to larger rockets that use turbopumps in the tens of megawatts.
Biting the hand that feeds IT
