Gravity Turn Heuristic for RSS

[Silavite]

I've been playing a bit of RP0 lately, and I am having a bit of trouble figuring out how quickly I should make my gravity turns. I especially have trouble with low TWR upper stages, such as ones using an RL10. Does anyone have a heuristic for doing gravity turns that could apply here?

[Laie]

First off, you're aware of the RO wiki? https://github.com/KSP-RO/RealismOverhaul/wiki

My personal baseline recipe for starting a turn is to pitch by one degree for every 10m/s of velocity. So by the time I reach 100m/s, I'm pointed at 80°, and 70°@200m/s -- this approach yields usable results over a wide range of TWRs. Usually it leads to me crossing 30km@30° - that breakpoint, too, seems to work well for many LVs.

However, in RO you usually cannot do a full gravity turn all the way to orbit. At some point (often around 30km altitude) you stop following prograde and start doing whatever it takes in order to make orbit. More often than not, that means pitching up, or at least holding steady while the prograde marker moves downwards. Thor-Able is the notable exception: get her to 30°@30km, then point at the horizon. But most others need to keep their nose pretty high for a while.

[Hydrothermalventclam]

Also if you want, mechjeb has a launch autopilot that implements the Surveyor launch guidance algorithm.  It pitches over to about 10 degrees shortly after launch, then holds there until prograde catches up, then follows prograde until the rocket is mostly out of the atmosphere.  From there, the Surveyor algorithm takes over, and flies the rocket basically horizontally until it reaches orbit.  I have had great success using this with RL-10 powered upper stages.  When I flew a similar path manually I was also able to make orbit; however, it was not as accurate.

I think mechjeb does almost what is described on the RSS-RO wiki, but with more math to hit the target orbit more accurately.