Nuclear Engines vs LV 909

[nickrich]

Hi

I'm a little confused about how and when you use the Nerv engines,  .... i can see they've got a great ISP, but are heavy and provide little thrust. When calculating the DV (removing the oxidiser) for various small and slightly larger craft they never seem to be better than using the LV-909 ... am i missing something???

[Padishar]

Use fuel tanks that only hold LF.  When you use an LF+O tank with the O removed, the best wet/dry mass ratio you can get is about 5:1 rather than 9:1 for LF only tanks.

[steuben]

tech level as well. unless you are focusing on getting the lv-n you'll get the 909 first

[nickrich]

Thanks, it was the LF only tanks that threw me, i'd only looked at the 'rocket' tanks

[cantab]

You also might not be packing enough delta-V. In general when your delta-V requirements are low, a light but inefficient engine can do better than a heavier high-Isp one.

[bewing]

Also, it only costs 9/20ths as much to refuel a NERV.

[Gaarst]

A quick rule of thumb:

• < 20t, use LV-909
• > 20t, use Nukes

20t is approximately the mass of a ship where nuclear engines become better than LV-909 in terms of dV (lots of graphs have already been done on this but I don't want to go and search for them, so you'll have to believe me without any proof).

Edited May 14, 2016 by Gaarst