4 ms·

I wonder how much this could be mitigated by extra-rocket energy delivered while the rocket is still close to the ground - e.g. a cartoonishly large slingshot.

drusepth 7y ago
Or a comically large refueling hose hooked up until it hits orbit. I guess in that case you'd probably be fighting gravity even more trying to push fuel up the hose.
mey 7y ago
Ground laser propulsion has been considered. https://en.m.wikipedia.org/wiki/Laser_propulsion https://en.m.wikipedia.org/wiki/Laser_propulsion
derekp7 7y ago
There's also using chemical rockets for the first stage, then switching to nuclear for the second stage once clear enough of the ground to minimize fallout. Radiation pollution wouldn't be pleasant, but future advances could potentially minimize that also.
- marktangotango 7y ago
  NERVA XE was damn near ready to fly during the Apollo era for Mars missions. Would've made a hell of 2nd stage engine. https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA
sdenton4 7y ago
Unfortunately, drag force is proportional to the square of velocity... So the slingshot (or railgun or whatever) maybe gives you a nice acceleration at the start, but a LOT of that initial force will bleed off as drag early in the flight in the thick thick low atmosphere. (Consider the difference in difficulty of riding a bike at 15mph vs 16mph and 25mph vs 26mph... 25->26 requires a hell of a lot more effort, all due to drag.)
wahern 7y ago
Or you could just launch from a 12 mile tall tower: https://en.wikipedia.org/wiki/ThothX_Tower https://en.wikipedia.org/wiki/ThothX_Tower
- philwelch 7y ago
  Or a Lofstrom loop: https://en.wikipedia.org/wiki/Launch_loop https://en.wikipedia.org/wiki/Launch_loop Or you could fly a high-altitude airplane into a skyhook: https://en.wikipedia.org/wiki/Skyhook_%28structure%29 https://en.wikipedia.org/wiki/Skyhook_%28structure%29
  - c0bb 7y ago
    Im not qualified to know whether or not it is actually viable but I really like the Skyhook idea vs. a tethered elevator.

drusepth 7y ago

Or a comically large refueling hose hooked up until it hits orbit. I guess in that case you'd probably be fighting gravity even more trying to push fuel up the hose.

mey 7y ago

Ground laser propulsion has been considered. https://en.m.wikipedia.org/wiki/Laser_propulsion https://en.m.wikipedia.org/wiki/Laser_propulsion

derekp7 7y ago

There's also using chemical rockets for the first stage, then switching to nuclear for the second stage once clear enough of the ground to minimize fallout. Radiation pollution wouldn't be pleasant, but future advances could potentially minimize that also.

marktangotango 7y ago
NERVA XE was damn near ready to fly during the Apollo era for Mars missions. Would've made a hell of 2nd stage engine. https://en.wikipedia.org/wiki/NERVA https://en.wikipedia.org/wiki/NERVA

sdenton4 7y ago

Unfortunately, drag force is proportional to the square of velocity... So the slingshot (or railgun or whatever) maybe gives you a nice acceleration at the start, but a LOT of that initial force will bleed off as drag early in the flight in the thick thick low atmosphere. (Consider the difference in difficulty of riding a bike at 15mph vs 16mph and 25mph vs 26mph... 25->26 requires a hell of a lot more effort, all due to drag.)

wahern 7y ago

Or you could just launch from a 12 mile tall tower: https://en.wikipedia.org/wiki/ThothX_Tower https://en.wikipedia.org/wiki/ThothX_Tower

philwelch 7y ago
Or a Lofstrom loop: https://en.wikipedia.org/wiki/Launch_loop https://en.wikipedia.org/wiki/Launch_loop Or you could fly a high-altitude airplane into a skyhook: https://en.wikipedia.org/wiki/Skyhook_%28structure%29 https://en.wikipedia.org/wiki/Skyhook_%28structure%29
- c0bb 7y ago
  Im not qualified to know whether or not it is actually viable but I really like the Skyhook idea vs. a tethered elevator.