RCS on EVE

[Moonk]

I landed a rover on Eve, it uses RCS engines to move. RCS consumes much more fuel in second then on Kerbin, about x10 or x20 more. Why?

I know i could use electric powered wheels, but i bring my RCS rover with me, just curious why it consumes much more fuel then maximum engine info?

Edited August 19, 2015 by Moonk

[Tank Buddy]

Most likely because the RCS thrusters have a lower specific impulse (efficiency) under the pressure of Eve's atmosphere near sea level than on Kerbin; 5 atm vs. 1 atm.

[Edax]

And let's not forget Eve's 1.7g Gravity compared to Kerbin.

[Moonk]

Yes, but how could engine consume more fuel per second? it should produse less impulse , but not consume more fuel per second..

[Ripper2900]

I believe that the original way of doing motor efficiency in Ksp was to have engines working at constant thrust, but vary the fuel consumption accordingly to the current Isp.

That algorithm is probably what remains with those thrusters?

[CalculusWarrior]

Yes, they likely kept the old way of doing specific impulse calculations in the RCS jets, if you're seeing propellant flow change with ISP (post-1.0, mass flow is kept constant, as it is in reality). You'd be best off with normal electric-powered wheels on Eve, and save the RCS rovers for places like Minmus where you can achieve ludicrous speeds on the flat areas there.

[Vegetal]

A little off-topic here but.....are you planning on retrieving those kerbals sometime in the future?

[Sharpy]

I believe it's not just RCS. The Cygnus SSTO rocket launchers seem to deplete half the available fuel by the time they reach 10km and some 400m/s, then the rest to the orbit. So high pressure doesn't just reduce engine thrust, but also increases fuel consumption.

[KerikBalm]

rocket launchers seem to deplete half the available fuel by the time they reach 10km and some 400m/s, then the rest to the orbit. So high pressure doesn't just reduce engine thrust, but also increases fuel consumption.

I higly doubt that, based on what you said, your conclusions are unfounded.

Have you considered they just take a lot longer to reach 10km and 400 m/s?

Their acceleration against the 1.7Gs and 5 atms will obviously be much worse.

I'm guessing they kep the old way for the RCS, so that they still produce usefull maneuvering thrust, like when you use verniers

[Signo]

The answer is atmo pressure. (above somebody already wrote it I think.)

You want your Eve rovers to be electric and nuke powered (not enough sunlight to drive anything in a continuous way above 55 parallel)

[Moonk]

A little off-topic here but.....are you planning on retrieving those kerbals sometime in the future?

Sure i will someday. They need new rover to get research points from nearby biomes. Then they need some more fast vehicle to transport all crew to fine flat spot for landing and launching. Probably this spot must have some ore for refueling and must be at high attitude above sea level. I play on 0.2 science , so i have only Skipper engines, so there resque will be after they farm enough science for more powerful engines.

[Lukaszenko]

We will keep you to your word.

[Vegetal]

I think you'll do good to have a speech ready for people on kerbin, about how the brave kerbals on this mission knew the risks bla bla bla....you know, just in case.

EDIT: Did you ever launch from Eve into orbit?

[Moonk]

challenge accepted

[Moonk]

Resque Misson launched

[Moonk]

Refueling on Minmus orbit

[Moonk]

1st suprice. I cant decuple 2 Rhino middle stage engines with tanks...

But it works perfectrly on launchpad

40 t payload.. Looks like i dont have enough Delta V for Eva manuvers...

[Moonk]

Fuel proved just enough, continue of resque

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[Lukaszenko]

How's it coming along?

[Lynch]

Atmosphere pressure force acting on RCS might be pushing it out with much faster pressure? A realistic approach?