What throttle do you launch on?!

[NecroBones]

Almost always 100%. I usually don't end up over-engineering my "from the pad" TWR. That's by design. I don't like for my rockets to require me to remember different throttle settings, if I launch a duplicate later. So I'm more likely to tune the TWR in advance by engine choice, or more rarely, tweaking the thrust limiter.

[montyben101]

Always 100% to start with, when getting to the point were I want to orbit at I gradually decrease the engines and then cut them off once there

[John FX]

Whatever gets me a TWR of 2.1 on the pad. Any more than that and things can explode on the way up with solid boosters (DRE, FAR)

[Rainbow-Dashie]

Floor it! (100%)

[RizzoTheRat]

Recently I've been using solid fuel boosters throttled to give me a TWR of about 1.2, and then a single main engine running about about 20% thrust to give me good steering via vectored thrust. If I stick a smallish LFO tank on top of each booster I can still have my main tank pretty much full when the booster burn out and throttle up to 100%

[QuesoExplosivo]

100%, until I get up to terminal velocity.

[Giggleplex777]

For rockets with liquid fuelled engines, I ignite them at 30% throttle on the pad and then throttle up to 100% with the shift key. I like doing this to emulate a real launch where the engine has to rev up on the pad before taking off. My rockets usually have a TWR of 1.2-1.5, so 100% throttle is necessary.

It's the same with rockets with solid rocket boosters, except this time I ignite the boosters (and detach launch clamps, if there are some) after the main engines are at 100%. The core stages always have a TWR >1, and with boosters the TWR is usually about 1.5. This makes the boosters actually useful as a thrust argumenter rather than just adding a bit to the delta-v.

[magnemoe]

100? all the time, let mechjeb control the throttle.

If I don't have mechjeb I try to get TWR at launch between 1.6 and 1.9 depending on staging then don't touch it unless I see I go to fast,

[Starman4308]

Almost always 100%. If you ever use less than 100% until the final stages of ascent/circularization, you have either failed to optimize your design, or you messed up your gravity turn/pitch profile. Either option is failure.

[Voculus]

Balls to the wall!

[Tomski]

I start at 100% and then dial back gradually to keep accelleration at a controlled rate and not exceed 200m/s below 10000m altitude (note: I can't run FAR yet as it causes problems with the game, so this is for stock aerodynamics).

Once approaching 10000m, I push the throttle up to 70 or 80% to prepare for first stage jettison. Then I control the throttle on the second stage to prevent time-to-apoapse from exceeding 1 minute. Usually this means gradually dialing the throttle down to 10% or less and keeping the rocket pointed at prograde, depending on my payload, instead of "coasting to apoapse" the way I used to before. I also do a sort of pseudo-gravity turn (keep it less than 5 degrees below 10000m) just to move downrange from my launch pad, just so any rapid unplanned disassembly doesn't go raining flaming rocket parts all over my fancy cosmodrome. I usually put things into a 72-75km orbit unless the mission demands otherwise.

[SRV Ron]

100% on liquids, SRBs boosters tweaked depending on their power output to reach between 5,000 to 10,000 by burnout. Then, gradually do the gravity turn on a continuous basis until a 100K apogee is reached.

[Norpo]

Generally, 40%-ish while boosters are going and i'm under 10km, then as soon as boosters are gone I go 100%, but it really depends on the rocket.

[Jim Kernan]

100%, 100% of the time

[UmbralRaptor]

100% until limited by terminal velocity, if ever.

Pretty much this. There have been designs that needed to start at ~50% and then smoothly go up to 100% to avoid breaking, but they were very much the exception.

Liquid fuel engines (even the NASA ones) have quite limited TWR. There's not the same tradeoff between Isp and TWR that there was before they were added, but over-engining is still a good way to have expensive craft that are terribly short on payload. (If you never spend much time at 100%, you have engine mass that could have been used for fuel, payload, or removed entirely to reduce cost.) Most designs stay below terminal velocity and only need to throttle down for fine maneuvers.

SRBs are a rather different case. If you treat them as "normal" engines with some fuel attached, they have absurdly high TWRs, meaning you are more limited by things like heat, mass ratio, Isp, and control authority. Throwing a thrust limiter on some stages is a lot less hassle. Especially when a decoupler is more expensive than an RT-10...

Edited November 4, 2014 by UmbralRaptor

[Taki117]

Because I use FAR I don't have to worry about Terminal Velocity however I launch at 100% throttle unless my engiens are overheating, then I back off throttle to prevent engine explosions.

[sal_vager]

A long time ago, a member known as closette worked out that rockets were really inefficient while still below 100m/s during ascent.

Now, I don't know if that's still true, but I gun it at full throttle at least until I'm over 100m/s, then I'll throttle back to avoid atmospheric drag losses.

Seems to work

[Skorpychan]

100% all the time. I throttle down once I hit terminal, then play with it so I'm terminal (or close to) the whole way up.

[numerobis]

A long time ago, a member known as closette worked out that rockets were really inefficient while still below 100m/s during ascent.

Closette referred to Goddard's problem, but you only got half the solution: for ideal mass efficiency with weightless engines in an exponentially thinning atmosphere, you want to be at terminal velocity going straight up all the way (which is about 100 m/s at the surface) to maximize the altitude you will reach. Lower and you have too much gravity loss, higher and you have too much drag loss. Keep TWR about at 2, and you'll match terminal velocity all the way up (you need a tiny bit more since terminal velocity increases, until you start getting high up and you've violated the assumptions in Goddard's problem).

Since engines aren't free and since you want to eventually reach orbit, the optimum is going to argue for TWR lower than 2, and gunning them.

[merendel]

Depends on the type of the launcher. If its pure liquid launch I normally design it in such a way that 100% all the way is viable. If I'm useing a fair bit of SRB's I consider the solids my first stage. With the solids I may fire the liquids at launch to get up to speed and to have some control authority with the gimbles till I'm going fast enough for control surfaces to work but usualy they will be cut off after the first few hundred meters till solid burnout.

[thunderstar]

100% most of times unless i use rockets that tend to overheat, also i always try to desing them with a lot of TWR i hate long launches but also not too much or they'll burn in the atmosphere.

[ZedNova]

I set it to 110% and smash the space bar.