What percent throttle do you use on take off?

[Francesco]

100% of course: even if you had a TWR equal or more than 2, you'll have to reach terminal velocity as quick as possible anyway (around 100 m/s at ground level).

if efficiency is what you're after, you either need a table with the terminal velocity values for different altitudes, or you look at kerbal engineer's displayed info, or you rely on mechjeb.

[UmbralRaptor]

My throttle is the VAB. If I have to throttle back, it means I'm carrying dead weight in the form of extra engines-- so I remove some and/or rejig the staging so's to jettison them sooner.

Of course, given how often I have a rocket with 1-3 engines on the pad, minimum gauge is an issue impeding efficiency...

[foamyesque]

Of course, given how often I have a rocket with 1-3 engines on the pad, minimum gauge is an issue impeding efficiency...

Use smaller engines then.

[stijnovic]

What do you all mean by "terminal velocity"? That would be the velocity you would reach when falling down, when drag forces are equal (but opposite) to the gravitational acceleration. So I would guess that this is only true if your thrust-to-weight ratio is exactly 2 (to go from -1g to +1g). But my rockets usually have a starting t/w-ratio of 2.5 and this increases as the rocket burns fuel.

Anyway, is there a way to calculate your terminal velocity?

[Flixxbeatz]

I do control my throttle (ie. launching at <50-20% throttle, depending on the weight of payload, and gradually reducing throttle as tanks go empty to compensate) before, thinking that I would save fuel on the way to orbit. I've tried doing it on the later versions and it didn't work the way I've expected it, so I'm sticking to full throttle at liftoff no matter what the weight of payload is (but not if using mainsails as booster cores).

Take

for example. Watch how I meticulously control the throttle on the way to orbit. I've rebuilt the same thing back in 0.18, and flew it like how I flew it before. I didn't even made it outside the atmosphere. I've tried the full throttle liftoff, and it worked well.

[Hannu]

It depends on rocket. If I use one mainsail and 6 or 8 solid boosters in small booster, I can use about 20 % of Mainsail's thrust just to steer ship. Other example is a rocket with little small TWR, which can use full throttle from pad to orbit. Typically I use 2 stages to orbit and second stage is nearly always at full throttle from ignition to MECO. The most huge rockets (1500-2000 t) are so unstable that I must be very careful with Mainsails. Automatic steering is very aggressive and Mainsails have so large gimbal angle that they can shake rocket to break.

[gzusphish]

Granted this was a very simple rocket, and these numbers won't stay the same for another rocket, but using three stages of throttle, I was able more than double the distance it could climb. Does that translate to fuel efficiency?

Here are results from several tests on 0.21.1 using all stock parts and launching as straight up as possible. Maximum altitude was measured from the point where the ship actually physically passed through apoapsis.

The ship was a single stage consisting of an Aerodynamic Nose-cone, Remote Guidance Unit, one FL-T400 fuel tank, and one LV-T30 engine.

Launch pattern 1

- 100% until burnout

30.9km

Launch pattern 2

- 50% until 10km

- 100% until burnout

60.9km

Launch pattern 3

- 25% until 10km

- 50% until 20km

- 100% until burnout

73km

Launch pattern 4

- 20% until 10km

- 40% until 20km

- 100% until burnout

56.6km

Launch pattern 5

- 25% until 10km

- 40% until 20km

- 100% until burnout

72.7km

Launch pattern 6

- 25% until 20km

- 100% until burnout

72.9km

Launch pattern 7

- 33% until 10km

- 66% until 20km

- 100% until burnout at 21km

74km

Launch pattern 8

- 33% until 10km

- 50% until 20km

- 100% until burnout at 21km

76.6km

Launch pattern 9

- 33% until 10km

- 40% until 20km

- 100% until burnout at ~21km

78km

Edited August 22, 2013 by gzusphish
Misplaced alt from launch 8

[The Jedi Master]

If it doesn't involve mainsails on orange tanks, just pump it at 100% until your out of the atmosphere.

[annallia]

I go 100% When I see the needle going up near 200 (not sure what it is... m/s?) I throttle back until it stops gaining speed.

When I hit 6500 I throttle up a little as I start my gravity turn. When I hit 10,000m I throttle all the way up.

[Joshington]

I go for 100% at the start, then slow down to conserve fuel.

[Kerbart]

I'm going up Kerbal style, at 100% and for a damn good reason: the game doesn't let you go up at 110%

[Dkmdlb]

edited for delete: necro thread.

[MaGicBush]

So what's terminal velocity in KSP exactly what speed do I throttle down(don't want to read through 6 pages which is one annoying thing about this forum way to many people like Kerbal haha)?

Edited August 22, 2013 by MaGicBush

[GDJ]

Full blast, full torque, full speed right to the end.

The only time I feather the gas is orbital manoeuvres or flying extremely high in a Jet aircraft.

[annallia]

So what's terminal velocity in KSP exactly what speed do I throttle down(don't want to read through 6 pages which is one annoying thing about this forum way to many people like Kerbal haha)?

Wonderful little chart on the wiki page: http://wiki.kerbalspaceprogram.com/wiki/Kerbin

[MaGicBush]

Wonderful little chart on the wiki page: http://wiki.kerbalspaceprogram.com/wiki/Kerbin

Nice chart, bookmarked . Thanks for the help!