Designing Launch Vehicles

[SRV Ron]

The homemade rocket parts are awesome! What mod are these parts from?

Professor Phineas Kerbenstein Wonderous Vertical propulsion Emporium

Landed on Minmus;

Currently, the balloon doesn't work until that mod gets updated for 0.90 beta.

Edited January 20, 2015 by SRV Ron

[Pecan]

How I design depends on what I'm optimising:

For mass/payload-ratio = asparagus, core + 2 to core + 6 or, if I'm really messing around, twisted candle.

For low part-count, simple construction and quick flight = SSTO rocket.

For cost = SSTO jet 'tail-sitter'.

For crew, sometimes = spaceplane.

If I really, really, get bored then I might make a cargo spaceplane every now and again, but I hardly ever bother to fly them.

Assuming we're discussing things that go up then across, I've been using lower and lower launch TWRs, now preferring 1.2 - 1.4 over the 1.6 - 2 I used as a newbie. Mostly that's because I'm using fewer stages or just one though, so the TWR is as high or higher at burn-out and the average probably about the same.

Most recently I'm only building SSTOs though and it's just a lot simpler to build launch vehicles to get the most from an engine (type) and pick the payload-capacity you need:

In round figures a T30 will SSTO 1.5t (two will SSTO 3t, etc.) aiming for 4,900m/s deltaV to allow for de-orbit and 'chute assisted powered landing. Similarly, a skipper will SSTO 5t, a mainsail 11t and a KR-2L 26t.

While a KR-1x2 will SSTO 14t you're better-off with two mainsails, even if you're wasting a lot of their 22t potential. A KS-25x4 costs 50% more per tonne than a KR-2L and can only do 27t anyway.

1-5 T30s, skippers, mainsails or KR-2L give reusable launch vehicles for 1.5, 3, 4.5, 5, 6, 7.5, 10, 11, 15, 20, 22, 25, 26, 33, 44, 52, 55, 78, 104 and 130 tonnes, even without starting to mix them. Since the heaviest single thing I usually launch is 40t and most of my payloads are in the 20t - 40t range that suits me fine.

(@ Wanderfound, if he wanders by; see, I haven't forgotten, just really bogged-down in work)

Edited January 20, 2015 by Pecan