Optimal launch profile?

[Guest]

I’m currently playing a save in Real Solar System and trying to design missions within some self imposed constraints such as size of rocket and volume of fairings ect... So far I’m getting pretty good at getting things into LEO but because of the constraints I can’t just launch anything up there so how I’m utilising my launch vehicle’s deltaV is something I’d like to try work on.

TL:DR - How would I go about figuring out how to make a optimised launch profile? 

Ive kinda been trying to make my launches as gravity turny as possible but there’s a fine line between staying in the atmosphere too long and becoming way too elliptical. 

(If I just try getting most of the way out of the atmosphere before trying full thrust for horizontal I end up pointing pretty far away from prograde for a decent amount of time and this seems like it would be less delta efficient for some reason but I duno.)

Edited July 27, 2019 by Guest

[The Aziz]

I found a launch profile for first Falcon Heavy flight, maybe you will find it useful

[Loskene]

While the G-turns in RSS are fundamentally the same as stock, the scale differences and tighter deltaV budgets make it much more sensitive to losses from steering, drag, etc. Many hardcore RO/RSS players use kOS scripts, mechjeb or other autopilot mods to fine tune and revise their trajectories on the fly to get the most efficiency from the tighter margins. Ideally you want to have it so that rather than boosting up out of the atmo and coasting to apo before circularising, as you would in stock, arrange it so the engines are burning for the entire duration and your vertical speed is near 0 at apo while circularising. Requires more planning in your rocket and launch profile ahead of time, tweaking the staging/burn time/TWR to maintain an optimum profile for the entire flight. You can't really brute force it as easily as in stock, an efficient gravity turn is more important, or else your rocket will end up ballooning in size to make up the lost dV. Tyranny of the rocket equation. Even flying "manually" still tends to mean using Smart A.S.S. for steering one degree at a time and carefully managing your time to apoapsis, vertical speed and acceleration curve.

There's really no one-size-fits-all gravity turn for rockets in RSS though, the exact profile you take depends heavily on the TWR/ISP/drag of each stage. Low-thrust upper stages may need to veer wildly above prograde to make sure they don't fall back down during the long circularisation process, while solid motor upper stages may just need to clear the atmosphere and burn like hell at the horizon, even pointing down to make sure the orbit isn't lopsided. I don't know how well it works in RO, but in stock I find the GravityTurn mod very useful for finding the optimum launch profile for your rocket, as it refines itself every time you repeat the launch to minimise losses. It's good to just watch what it does and learn its methods, though don't let it control staging, especially in RO, best handle that yourself or ullage motors and interstage fairings will confuse it.

In any case if you already know the fundamentals of the gravity turn then all you need is practice to get good at it in RSS, and eventually you'll be routinely building rockets with exactly the dV needed to reach LEO and not a single drop more. Good luck.

[Gargamel]

Moved to Gameplay Questions