Gravitational maneuver

[Gloom Demon]

I have read the Wikipedia entry on making a gravitational maneuver in KSP, however I fail to see it's effect.

I get my rocket to 100 m/s, switch to orbit on top of the Navball and start turning the rocket left, towards prograde.

Strangely - the prograde marker is way to the left when I start the maneuver, while the Wiki states entry that the gravitational maneuver should be done by small adjustments all the way up, not just one single turn to the horizon. And after that I fail to see any big improvement in height reached when compared with a strictly vertical flight.

Maybe I am missing something here?

Edited October 13, 2015 by Gloom Demon

[Tex_NL]

The reason you see a large difference between orbital and surface is simple: Kerbin rotates. Even with no or minimal surface speed you still inherit all of Kerbins rotational momentum.

Solution: Don't switch to 'orbital' manually, stay in 'surface'. The system will switch to 'orbital' automatically once you get higher up and it becomes relevant.

[FungusForge]

The prograde marker is off to the left because the orbital velocity is different than the surface velocity. To see this, stay parked on the launchpad and switch to orbital velocity, it will read something around ~160m/s. Because of this its better to let the game automatically switch to orbital velocity, rather then switching it while (presumably) still in the lower atmosphere. From my experience you want to start the turn based on altitude, not speed. Generally I start the turn around 8000m up, and if I do it right, when the navball switches to orbital velocity the prograde marker is within a couple of degrees of 45. From there I try to keep the prograde marker at 45 until my apoapsis is around 75km or so. Then I just coast within half a minute of the apoapsis and make the burn to orbit.

[FyunchClick]

With v1.004, I usually start a 5 or 10 degrees turn to the East right off the Launchpad, then turn SAS to prograde hold in with the nav ball in surface mode, that way the drag from the atmosphere is straight back and you don't have stability issues.

If needed, I'll nudge it a bit so I hit about half of 45 degrees at 2.5 km altitude, 45 degrees at 10. Then when my apoapsis hits 50/60 km, I'll throttle to get apoapsis about 45 seconds in front of me, and I'll let it drop down further the closer I get to my intended orbit height. This will usually get me in a neat 70/80 km orbit. I only bother gunning straight for the horizon at around 35/40 km altitude if the craft has such a poor TWR that I'm afraid I may not be able to hold the apoapsis at 30/45 seconds ahead.

I don't bother switching the nav ball to orbit mode, it'll do so by itself when you leave the atmosphere, and the stability that prograde flight in surface mode offers, up until about 35 kms or so, greatly helps getting even iffy designs up without too much problems.

The starting angle right of the Launchpad kinda depends on whether it's top-heavy and how fast the acceleration is; if it accelerates fast or is very stable, you'll need a bit more angle to start with, if it's slow or top heavy, a bit less is good.

I'm sure there's more efficient ways, but this works for me and it's pretty easy.

Edited October 13, 2015 by FyunchClick
misc spelling

[Gloom Demon]

Thanks guys :-)

[Highguard]

...And after that I fail to see any big improvement in height reached when compared with a strictly vertical flight.

Maybe I am missing something here?

There is no improvement in height using a gravity turn.

Which is the point :- height is easy, height is not the issue, horizontal velocity to get into orbit and stay in space is the issue. A gravity turn is the most efficient way to build horizontal thrust.

[OhioBob]

I don't bother switching the nav ball to orbit mode, it'll do so by itself when you leave the atmosphere, and the stability that prograde flight in surface mode offers, up until about 35 kms or so, greatly helps getting even iffy designs up without too much problems..

If I remember correctly, the velocity indicator switches from surface to orbital after passing an altitude of 36,000 m.