3 ms·
The rocket equation is not directly applicable. An electric car still works if it has less capacity and lower energy density. It is just slower and or has a low
by bagels 3y ago
The rocket equation is not directly applicable. An electric car still works if it has less capacity and lower energy density. It is just slower and or has a lower range.
Rockets need to produce >1g of acceleration or they don't get to leave earth.
- Dalewyn 3y agoIt is because an electric vehicle needs to move its own batteries as part of itself (obviously), but you also need more batteries to provide competitive driving range/power because the energy density is so low. Thus, you need to install more batteries to compensate for the increased workloads that a truck would forseeably experience, but you need more batteries to convey those batteries which requires bigger motors which requires more batteries and herein lies the Tyranny of the Rocket Equation. At some point you need a breakthrough in energy efficiency or energy storage density because you hit an upper practical limit on how much energy storage you can haul around. ICE cars and trucks must also technically contend with this, but in practice they do not because fossil fuels are so energy dense that we almost never meet that upper practical limit.
- lazide 3y agoNot really though? You have a similar (but not quite as bad) multiple for ICE cars with engines/transmission/fuel. Rockets it’s exponentially worse. Which is why the saying.
- jameshart 3y agoThe rocket equation says nothing about how much acceleration you're going to get. It relates fuel mass and exhaust velocity to payload mass and delta-v. The 'tyranny' isn't 'you didn't accelerate fast enough and you will not go to space today', it's 'for a given rocket exhaust speed capability, there is a maximum payload you can possibly lift to a target delta v (i.e. to a target orbit or planet or whatever), no matter how much fuel you throw at the problem'.