Same propellant consume on different engines? Same consume on different thrust?

[InF3RNo]

Hello, I'd like to know if even with different engines you'll consume the same propellant than others? Like in this image below:

There's no difference in the details, so I presume they consume the same quantity?

Also I want to ask if the engines consume less when the spaceship is less thrusted than when going full thrust?

Regards,

InF3RNo.

Edited July 6, 2013 by InF3RNo

[Darren9]

The ISP is an "Efficiency rating", higher ISP engine will produce more acceleration with the same amount of fuel than a lower ISP engine.

The max power (thrust) really just determines how quickly the fuel will be used. If two engines have the same ISP the higher thrust engine will burn the fuel at a faster rate to create the extra thrust.

Reducing the throttle reduces the fuel-use rate and also the thrust, it doesn't change the ISP though - the engine still has the same efficiency.

[Johnno]

I had written just about the same reply as Darren9 (ninja'd), only thing extra I can add is that you can view your fuel usage ingame by clicking your resources tab, you'll see resource usage per second within paranthesis on the right.

[Sirrobert]

The propellents tab is the RATIO in which each is consumed. Pritty useles info for rockets, as tanks already come in those ratios anyway. But it gives you an idea of how much air jet engines would need if you felt like calculating it

[Tiron]

ISP is the technical abbreviation for 'Specific Impulse', it is indeed a measure of how efficient the engine is: How much Change in Velocity (More technically known as Delta V) you can get out of it for a given quantity of fuel burned. It can have units of either time or velocity. KSP uses the Time version, so the specific impulse of our engines is measured in Seconds.

A higher specific impulse value means that the engine will produce more Delta-V from a given amount of propellant, which is actually far more important than the consumption rate.

The propellents tab is the RATIO in which each is consumed. Pritty useles info for rockets, as tanks already come in those ratios anyway. But it gives you an idea of how much air jet engines would need if you felt like calculating it

Very true. It's especially confusing in the case of the Ion Engines, which lists consumption values of 12 electricity and 0.1 xenon: like the liquidengines it's actually just a ratio. The ISP of 4200 seconds on the Ion Engines gives actual consumption rates of 0.121 xenon and 14.548 electricty per second.

Edited July 6, 2013 by Tiron

[InF3RNo]

Thanks for the answers, setting thread as answered!