When do you begin your gravity turn?

[TheMoonRover]

From Kerbin, I typically start the turn at around 7.5km, then gradually pitch *ahem* yaw over to 45 degrees on the way to 12.5km. For a bigger launch, I go more or less straight up until I can be sure dropping a stage will not result in spontaneous unplanned disassembly when attempted at an angle. But it does depend on the rocket.

Anything without atmosphere: turn to the horizon (or slightly above it) as soon as the vertical velocity is enough to prevent you crashing into the terrain in your immediate vicinity.

Duna and Laythe: Somewhere in between.

Eve: You'll be struggling to build a rocket that can get a decent sized payload back from Eve, much less launch such a rocket from Kerbin in the first place.

Jool: Okay, that's just being silly now.

[gmpd2000]

As a FAR user (and the fact that most of my rockets are a little bit overpowered) I begin my gravity turn at 500m.

[Renegrade]

SAS on, turn it to prograde hold at about 100m/s, glides up comfortably at a sensible rate of turn to stop FAR complaining. Avoids the nasty rolling you can get if you start manually adjusting your flight.

Rolling? As in on the long axis? If you mean that, the moment of inertia on a craft's long axis is very, very low, which makes it very sensitive to any roll inputs (q and e manually, SAS will apply them as it sees fit). I always tweak down the roll input on any tailfins in use on rockets in FAR to about 15%.. I can't recall when these input scaling things appeared in FAR (wasn't too long ago), but they totally rock.

I'm actually worried that stock aero will still use the pathetic stock tweakables for control surfaces, and that it will be the "Blizzy Toolbar Crisis 2.0" (where a superior modded system is replaced by a vastly inferior stock system)

FAR, er, for the win!

(seriously though, look at that tweakable. THAT is a finely evolved product. It even supports negative deflection(not shown in this shot))

[MrSnappyTurtles]

around 7 for me

[Flixxbeatz]

I typically do gravity turns at around 7km-12km, especially for standard lifters.

But when the first stage is just too powerful, I do it waaaay too early, like this one:

[Wabbit]

FAR>Soup, so I always turn <300m and keep lightly tapping the D key.

[wolfedg]

I personally do a 4 stage gravity turn beginning at 10 km and lowering my angle 1/4 of the way every 10 km till at 40km i am flying level then when i reach 1600m/s I kill the engines and configure my maeuver node for orbit. On some rockets that are underpowered I have to wait longer to level off but generally this method has served me well.

[The Destroyer]

8-10km for stock

[jman508]

edited due to stupid things being said

Edited February 26, 2015 by jman508

[Jethro420]

I use FAR. I try to balance my thrust for a true gravity turn, using gravity and drag to do the work. It's great when you can get up to desired altitude/attitude without having to touch the controls after initial lift off. It's very satisfying, actually. ;-)

[Thomas988]

For me, when to start a gravity turn is not based on when a rocket reaches a certain altitude, but rather when a rocket a reaches a certain velocity. I've found if you're 10 kilometers up and start turning, but travelling only 10 meters a second, your rocket is going to fall right out of the sky. Here you should wait until you reach a speed where you vertical speed will not deteriorate as you turn. In another instance if you're 10 kilometers up and travelling 3,000 meters a second, you are going to be leaving Kerbin entirely. Here you should have started turning ages ago!

I start turning once a rocket reaches ~300 meters a second.

[Klingon Admiral]

I use FAR and start turning when my rocket breaches 1.3 TWR and/or have completed the roll program. I rarely launch into 0° these days.

[gooddog15]

I usually turn at 9000, however with vertically launched space planes, I turn whenever the atmosphere is not as thick

[Sampa]

about 19 km in stock, 25 in RSS

[Superfluous J]

For me, when to start a gravity turn is not based on when a rocket reaches a certain altitude, but rather when a rocket a reaches a certain velocity. I've found if you're 10 kilometers up and start turning, but travelling only 10 meters a second, your rocket is going to fall right out of the sky. Here you should wait until you reach a speed where you vertical speed will not deteriorate as you turn. In another instance if you're 10 kilometers up and travelling 3,000 meters a second, you are going to be leaving Kerbin entirely. Here you should have started turning ages ago!

I start turning once a rocket reaches ~300 meters a second.

If your rocket is 10km up traveling 10 m/s, your gravity turn is the least of your worries. Likewise with 3km/s (though admittedly they're different problems).

If you're concerned about efficiency* you should really design your rocket so it smoothly accelerates up to about 260m/s at 10km**, and continues to accelerate at about the same pace up to orbit. This will allow you to hug atmospheric efficiency at about 100% all the way up, and will make turning at 8-10km the best choice.

*And if you're not concerned about efficiency, timing your gravity turn is pointless. Just burn straight up like they do in Star Wars

**More specifically you want to be going 100m/s at 1km, 150m/s at 4km, 200m/s at 7km, and 260m/s at 10km

[roosterr]

My gravity turns are always based on speed and TWR. I usually turn @ 200m/s and vary my path based on the TWR. That seems to give me the most efficient ascent.

Also its important to turn slowly. If you turn too quick you are wasting dv.

MJ

Exactly!

It depends on the ship, so why base it on altitude at all? The greater the TWR, the sooner you can turn.

[Elowiny]

I start my gravity turn at around 9-10 km.

[celem]

As many folks have said, depends on the launch.

Generally 9km, very light launches will tip as early as 7, heavies as late as 14. If I have a large stage to drop around this point then I will delay the turn until the stage is clear, dropping mid-turn is a poor plan.

TWR is generally moot, I dont build stuff that has to lumber up the hill.

How aggressive the turn is (turn shape) depends on the total mass, a probe launch will rock over to the horizon very very early, heavy launches I wont tip past 20 degrees in atmosphere. The final factor is whether the payload is required to make any part of the circularization burn at Kerbin, if I have a heavy nuke powered thing that I can barely get into orbit at all then i'll make a wussy grav turn and spit it out to 100km where the LV-Ns have time to finish up even with horrid TWR, rather than an almost completed orbit where the window for burning is only 30 seconds.

[Candlelight]

Usually 10 km.But i sometimes like to immitate MechJeb, and i start it 7km.No matter how big or what the craft is.

[rennsport27]

I use FAR these days, so I generally aim to start tipping over at 1.5km, and slowly lean until I'm at a 45 degree angle by 20 km. Then I push it almost horizontal by 50-60 km depending on the rocket/target orbit. I doubt my method is the most efficient, but it mostly works and seems to make flying oddly shaped things doable as well.

[HafCoJoe]

Well I do my gravity turn based on speed instead of height. I start turning to 45 degrees once I hit 500m/s. This is about where the longer bar in the atmosphere meter usually is. The TWR of most of my lifters suits this turn well. When I hit about 750 m/s I start turning flat and reach my parking orbit of 100k.

[xnorb]

Like learnt from Scott: 10km

[WuphonsReach]

With FAR...

15km if the rocket lacks enough control authority to keep pointing forwards (i.e. CoL marker is forward of CoM).

5-10km for rockets with a TWR of 1.1-1.5 and enough control authority (fins / verniers / RCS thrusters) to hold attitude once the pitch-over maneuver starts.

[Bev7787]

20km up

[technicalfool]

Stock aero, about 7-8km to start, and gently nose over. I know the "rule of thumb" is 10km then a hard 45 degrees, but that just seems wrong somehow. <brag>Plus, I seem to get better-than-Mechjeb levels of efficiency anyway</brag>.

With FAR, probably nearer 3km, but a vastly more gentle turn. With both aero systems, I'll aim to be pointing the nose at the horizon once my apoapsis is around 50-60km or so.

With FAR+RSS, I'll start the turn about the same 3km or so, but this time I'll aim the nose at the horizon at an altitude of around 130 to 150km if I'm aiming for a 250km orbit.

Edited March 5, 2015 by technicalfool