Geostationary launch effeciency

[wrexecute]

Which of these would take less effort?

1. Launching something straight up to geostatic altitude and circularize?

2. Launching to a stable LKO then raise Pe to geostatic altitude and circularize?

[SSSPutnik]

I'd pick box number (1)

[Poynting]

There isnt much difference really as they are almost equivalent. However it is option 1 that is slighlt more efficient. Launch as if you were going into LKO but once your apoapsis reaches LKO alltitude just keep burning horizontally. Your apoapsis will then swing round to the farside of kerbin and you just need to push it up to GKO (Geostationary Kerbin Orbit) altitude. All this can be done whilst your periapsis never leaves the atmosphere (Therefore at apoapsis it requiring less Dv to raise it past LKO alltitude).

However the difference is only small, as the benefit arises from the slightly lower altitude at which you make the burn to reach GKO.

(Set Mech jeb to reach GKO orbit in the ascent guidance, with a turn end altitude of 80 km to see an illistration of the ascent profile i'm talking about)

Hope this helps!

[Kasuha]

Most efficient approach (but hard to pull accurately and not very practical) is bielliptic transfer with direct launch.

1/ launch, raise your periapsis to about -100 km (minus one hundred, i.e. still under the ground) and your apoapsis all the way up to the SOI boundary

2/ coast to apoapsis

3/ raise your periapsis to the stationary orbit level

4/ coast to periapsis

5/ circularize

Edited February 28, 2014 by Kasuha

[SSSPutnik]

Oberthing it eh Kasuha?

[wrexecute]

See, I was just firing them straight up like the first way. That explanation helps a lot. Kinda combines both ways, skipping LKO circularization. It even trimmed down my rocket a little, as it was slightly overpowered for the sake of just getting to 2868km very quickly before any major longitudinal changes relative to KSC. With a normal-ish launch profile, some patience and a 4hr period at 2868km, I only need to wait a few orbits before I'm back over KSC at the right altitude for an initial release.

[Red Iron Crown]

Bielliptic transfers do minimize delta V usage but they are tedious for what amounts to at most 3% savings versus a similar Hohmann transfer. And there are cases (this isn't one of them) where bielliptic uses more dV.