When do you do your Gravity Turns?

[Tank Buddy]

I have just standardized my procedure; I lean over to 75 degrees at 10 Km, then to 60 degrees at 20 Km, and then to 45 degrees at 30 Km. I manage the throttle to slow the vertical climb and allow for more horizontal motion. I continue at this angle until my apoapsis is about 5 KM under what I want (desired apoapsis), then burn to the desired height by thrusting at the horizon. I know that the apoapsis will rise during orbital insertion, so I guess you could leave 2-5 Km of wiggle room in that desired apoapsis value.

My question is when and how does the rest of the KSP community do their gravity turns. I was also wondering is anyone had done research or knows the most efficient method to preform a gravity turn

Poll to be included.

Edited November 15, 2013 by Tank Buddy

[oggylt]

I usually start a tinny bit turned, and gradually increase my turn angle by reducing thrust, at 10k I increase even more and reduce thrust so i wont burn too off from actual propagrade vector

[Scotius]

I too tip my rockets by some 5 degrees at 400-600 meters. Full blown gravity turn begins at roughly 11 kilometers. After that i try to follow prograde marker so apoapsis stays about 1 minute ahead of my ship.

[numerobis]

I tend to start the turn at 8km with a high TWR rocket. Looks like a low TWR rocket benefits from going a little higher first.

[Crown]

That's the pattern I use:

The Rest is done by feeling. Ap at about 70km and I try to keep the vessel in front of the Ap. I know this might not be the most efficient way but for be it works. So I stick with it.

Ones I mapped it using a graph with angle over altitude, and as far as I remember, it looked quite linear. As the usual ascent pattern (at least in MechJeb) looks like a mixture of and (with ).

[Dizzle]

I start my turn at around 12km.

[hugix]

about 10 KM to 45 degrees, and then keep my AP somewhere between 30-50 seconds in front of me.

[Specialist290]

Moving this to Gameplay Questions

Personally, mine is more or less fairly standard: Kick out a little (~85 deg) right off the launchpad, then start the major tilt somewhere in the realm of 8-12 km up, depending on my rocket's performance.

[Taki117]

Depends. If I'm using MechJeb I use it's ascent guidance (Never autopilot, unless it's a probe, then it makes sense) Otherwise it's straight up to about 7k (Or whenever the second set of asparagus boosters is clear) then pitch over to about 45° then burn to just above desired apoapsis, let drag bring it back down, circularize.

[SRV Ron]

If using SRBs, as soon as I stage them to liquid fueled engines, usually 5 to 8,000 meters. The turn is done gradually.

[Traches]

I just want to point something out because it bugs me-- "burn to 10km and then pitch over to 45 degrees" is not a gravity turn, and would be impossible in the real world.

An actual gravity turn is a small pitch over (15 degrees at the most) very early in the ascent, and then you allow gravity to pull your trajectory towards the surface until you're horizontal. In other words, you just point towards the surface velocity vector, and the planet's gravity turns you.

[annallia]

I generally start somewhere between 7km and 8km If for some reason I still have SRB's running I will continue straight up until they die out.

[NoPanShabuShabu]

For most of my flights I start a turn around 8000m with my nose pointed a little past the edge of the prograde marker so that it gradually turns the ship. I try to get it so that I'm pointing about 60 degrees through 10000m, and try to keep the prograde not too far from 45 degrees till over 30000m, then try to pull my heading to the prograde marker when it switches over to "orbital", normally that's about 25-30 degrees. After that, just see how well I'm getting up to orbital speed and how the ap is progressing. Heavy, low TRW ships I turn later and slower.

[The Destroyer]

I start around 7-10km.

[John FX]

Depends on the craft. Low TWr need to get some vertical speed built up before you start to turn but high TWR can turn earlier.

[Franklin]

around 7km and a slow, smooth tilt until i hit my desired apoapsis. but as important as it is to re-educate people on proper gravity turns, teaching people to adhere to the terminal velocity table is a lot more fuel-saving. far too many punch-it pilots.

[luchelibre]

I just want to point something out because it bugs me-- "burn to 10km and then pitch over to 45 degrees" is not a gravity turn, and would be impossible in the real world.

An actual gravity turn is a small pitch over (15 degrees at the most) very early in the ascent, and then you allow gravity to pull your trajectory towards the surface until you're horizontal. In other words, you just point towards the surface velocity vector, and the planet's gravity turns you.

You're going to to feel so smug when FAR is made stock, aren't you?

So many threads of, "[bUG] Can't gravity turn. Plzfix..."

[Traches]

You're going to to feel so smug when FAR is made stock, aren't you?

So many threads of, "[bUG] Can't gravity turn. Plzfix..."

Haha nah, I dislike smug people in general. I will get a good chuckle though

[Moar Boosters]

I build my rockets so big they're impossible to turn at high speed in the atmosphere. The only way to fly them is turn gently right at the start before you've built up any real acceleration.

Anything but the most gentle turn makes the g-force meter literally start bouncing up and down with the rockets oscillations, and will eventually tear it apart, so the standard "10km then 45 deg" is impossible. A realistic gravity turn is the only way to go.

Anyway...... I like to roleplay, so dropping boosters onto KSC is a big no-no.

[LitaAlto]

Question: Do you need to disable SAS for gravity turns to work? I'm presuming so but nobody's made it explicit, and I'm not sure how you could get a proper gravity turn (one small adjustment shortly after liftoff and letting gravity do all the rest) with SAS on--but maybe I'm missing something...?

[EdFred]

I use SAS all the time, ESPECIALLY on ascents.

[MonkeyFuzz]

In stock KSP, I'll begin my turn at 10km to about 45*, then gradually tilt further as Apoapsis rises. By the time it's around 40km, I'm usually tilted towards 70-80* and once AP hits 50km, I tilt to the horizon.

With FAR I'll begin my gravity turn by 0.5km and gradually tilt ever farther as my course indicator moves lower. By around 5km I'm near 45*. Since I end up hitting 1000m/s+ while still below 20-30km, the biggest worry has been my parachutes exploding due to excess heat (Deadly Reentry, of course). With that approach, the correcting final burn for orbit insertion is ~20m/s.

[Sirine]

On launch pad, switch the Navball mode from surface to orbit. Hit the launch sequence, notice the Prograde marker raise to 45 degree, start turn and let the marker maintain at 45 degree all the time until your desire altitude high, example 70km. stop engines. sail to 5 second. and perform orbit movement.

If you have a slow rocket (low TWR) you may consider 60 degree.

I find this method to be the best. It apply to all various type of rockets. and maintain a stable and good reference.

[Laie]

Question: Do you need to disable SAS for gravity turns to work? I'm presuming so but nobody's made it explicit, and I'm not sure how you could get a proper gravity turn (one small adjustment shortly after liftoff and letting gravity do all the rest) with SAS on--but maybe I'm missing something...?

If you want to do it like that, SAS will prevent it from working.

However, I am under the assumption that it's called "gravity turn" not because gravity tilts your rocket (there's enough other forces doing this, and much stronger ones at that), but because gravity bends your flight path. Build a rocket of not-too-high TWR (about two-ish) and point it at (say) 85° right after liftoff. You will see your prograde marker wander to the side even though the rocket remains in the 85° position. That's because gravity eats a good part of your upwards motion, but the sideways component adds up over time.

Or, a more useful example: later in the ascent you may well be pointing at the horizon; no up at all. Yet the apoapsis is rising. You're pushing the apoapsis over the edge of the world, while gravity is pulling downward, turning it into something circular-like.

As to the OP: My actual gravity turn starts sometime around 15-20km when I turn my attention towards time-to-apoapsis and climb rate: the former should increase steadily but not too quickly; the latter should be "high enough". If both conditions are met, I pitch down. If I'm already looking at the horizon, I throttle down. However, I start turning much sooner: the atmosphere gets thinner quickly, and pointing towards 70°@10km doesn't significantly increase the time it takes me to get there. But it means that my later turn will be not half as abrupt and sudden as it would be if I went straight to 10km and only started turning there. Good for fragile rockets.

[Superfluous J]

Question: Do you need to disable SAS for gravity turns to work? I'm presuming so but nobody's made it explicit, and I'm not sure how you could get a proper gravity turn (one small adjustment shortly after liftoff and letting gravity do all the rest) with SAS on--but maybe I'm missing something...?

Necro post is a necro post

There is no such thing as a "real" gravity turn in KSP. It just won't work. We refer to the turn you make once you've gotten out of the soup of the atmosphere (about 10km up) and follow to orbit with the same name though it's not accurate.