4 ms·

If only Curiosity were as fast as the KSP rovers... top speed is somewhere around 100 meters/hour, and usually more like 40!

TeMPOraL 10y ago
Should have strapped an SRB on the rover. Reminds me; I wonder just how much ion engines are overpowered in KSP compared to their real-life equivalents. Or, put differently, if one could replicate a hovering Minmus rover I made in KSP (which used ion engines to stay afloat for a long time).
- jerf 10y ago
  Minmus surface gravity is 0.491 m/s^2; current ion drives thrust with a couple hundred millinewtons, so I don't think a drive could even support itself against that level of gravity let alone with power and a ship attached. However, we currently design our ion drives for power-to-thrust efficiency and long-term effectiveness. I'm not sure what we could get if we designed them for maximal thrust. Especially since in real life, right now the answer to "Do you want a 'maximal thrust' ion drive?" is pretty much "Well, have you considered using... not an ion drive?", so I'm not sure I've ever seen a treatment of that question based on current tech.
  - creshal 10y ago
    > I'm not sure what we could get if we designed them for maximal thrust. Probably something with a worse specific impulse than a chemical engine.
  - Symmetry 10y ago
    The problem is less our ability to make the drives themselves have a high TWR (thrust to weight ratio) so much as that the power generation necessarily required to run them is very heavy. See here: http://hopefullyintersting.blogspot.com/2015/03/rockets-electric-propulsion.html http://hopefullyintersting.blogspot.com/2015/03/rockets-elec...
  - skykooler 10y ago
    The VASIMR engine is sort of that - an ion engine designed to be able to increase thrust when needed.
- creshal 10y ago
  KSP: 4200s Isp, 2000 N thrust Real life: 2000-20000s Isp, 0.01-2.5 N thrust KSP's ion engines are hilariously overpowered in terms of thrust (and thrust-to-weight ratio) and power efficiency. It's a necessary change, however, since KSP is ill-suited for transfer burns several months long.
pavel_lishin 10y ago
The flip side is that Curiosity has never, to my knowledge, flipped over and tumbled at near-escape-velocity, shedding solar panels and scientific instruments as it goes.
Declanomous 10y ago
That really is slow. My brain interpreted that as 100 m/s, and then 40 m/s, and I read the sentence a few times trying to figure out if you meant that rovers go that fast in KSP before I figured out it said 100 m/hour.

TeMPOraL 10y ago

Should have strapped an SRB on the rover. Reminds me; I wonder just how much ion engines are overpowered in KSP compared to their real-life equivalents. Or, put differently, if one could replicate a hovering Minmus rover I made in KSP (which used ion engines to stay afloat for a long time).

jerf 10y ago
Minmus surface gravity is 0.491 m/s^2; current ion drives thrust with a couple hundred millinewtons, so I don't think a drive could even support itself against that level of gravity let alone with power and a ship attached. However, we currently design our ion drives for power-to-thrust efficiency and long-term effectiveness. I'm not sure what we could get if we designed them for maximal thrust. Especially since in real life, right now the answer to "Do you want a 'maximal thrust' ion drive?" is pretty much "Well, have you considered using... not an ion drive?", so I'm not sure I've ever seen a treatment of that question based on current tech.
- creshal 10y ago
  > I'm not sure what we could get if we designed them for maximal thrust. Probably something with a worse specific impulse than a chemical engine.
- Symmetry 10y ago
  The problem is less our ability to make the drives themselves have a high TWR (thrust to weight ratio) so much as that the power generation necessarily required to run them is very heavy. See here: http://hopefullyintersting.blogspot.com/2015/03/rockets-electric-propulsion.html http://hopefullyintersting.blogspot.com/2015/03/rockets-elec...
- skykooler 10y ago
  The VASIMR engine is sort of that - an ion engine designed to be able to increase thrust when needed.
creshal 10y ago
KSP: 4200s Isp, 2000 N thrust Real life: 2000-20000s Isp, 0.01-2.5 N thrust KSP's ion engines are hilariously overpowered in terms of thrust (and thrust-to-weight ratio) and power efficiency. It's a necessary change, however, since KSP is ill-suited for transfer burns several months long.

pavel_lishin 10y ago

The flip side is that Curiosity has never, to my knowledge, flipped over and tumbled at near-escape-velocity, shedding solar panels and scientific instruments as it goes.

Declanomous 10y ago

That really is slow. My brain interpreted that as 100 m/s, and then 40 m/s, and I read the sentence a few times trying to figure out if you meant that rovers go that fast in KSP before I figured out it said 100 m/hour.