Engine Hints

[Xyphos]

Mammoths & Vectors have a max ISP of 315, Rhinos have a max ISP of 340.
Rhinos make for a great middle-stage and they were designed for that purpose.
However on Kerbin, Rhinos will have an ISP less than 315, meaning it's better to use Mammoths & Vectors below 7500 meters.
I recently tested this, and Rhinos don't achieve 315 ISP until 7500 meters in Kerbin's atmosphere.
Just thought I'd share this.

[FancyMouse]

Using KER you can try out in VAB without flying. The break-even point for these two engines are at 6.2km on Kerbin where their Isp is 308.0s.

Personally I don't care - as long as it doesn't perform poor in atmosphere, I don't care Isp for first stage engines.

[Xyphos]

1 hour ago, FancyMouse said:

Personally I don't care - as long as it doesn't perform poor in atmosphere, I don't care Isp for first stage engines.

Well, it kind of matters if you're making a rocket-powered SSTO heavy cargo plane;
set a TWR of 0.7 and let the wings do the lifting, but Mammoths would perform better below 7500 meters.
once you're above 7500, you're best off toggling over to twin Rhinos all the way up.
I recently learned this from my tests, got a 129 ton payload to LKO this way;
previous attempts with Mammoths-only proved unfruitful.

[Plusck]

A plane with a Mammoth and twin Rhinos?

I've not done much with planes yet, but I'm surprised there are wings that could support such a beast. Maybe you should clarify that you're talking about planes / SSTOs in your OP / thread title...

[moogoob]

1 hour ago, Plusck said:

A plane with a Mammoth and twin Rhinos?

I've not done much with planes yet, but I'm surprised there are wings that could support such a beast. Maybe you should clarify that you're talking about planes / SSTOs in your OP / thread title...

I made a super-massive SETO shuttle powered by a Mammoth so... The wings aren't the issue. Balancing against that massive engine is.

[Nich]

Mammoths always have better DV for a single stage for a given twr