Automatic flight to orbit.

[K^2]

I've seen a number of various approaches to this over the years, from mods either specifically designed to do this or flexible enough to allow for it, like kOS, to really hacky things like simply timing a separatron to tilt the rocket at the right altitude. What I was looking for instead is ability to perform a gradual gravity turn in vanilla KSP, and while I've done some experiments with fins attached to servos, the results have not been very reliable. Recently, I got a thought, what if instead of trying to force the rocket to tilt over, we trick SAS into thinking it already has. So I slapped a probe core onto a servo part, added some curves and activations to a KAL unit, and, well, the results were actually really nice. This can still use a bit of polish, but the entire control unit fits in a single 1.25m service bay and can be tuned for whatever rocket you want to send to orbit.

 

I have found some interesting gremlins while working on this. It looks like the engine gimbals don't want to play nice with SAS if the axis the engine is aligned with differs wildly from the orientation of the control-from point. This isn't causing any issues during the first stage operation, but I had to shut down the gimbal on second stage and rely on reaction wheels only, because if I didn't, the second stage would spin wildly out of control the moment it ignited. There are also problems inherent to SAS use, like the fact that the lock orientation can drift over time, and that is definitely the case here, and you have to compensate for it. However, all that really means is that there is a bit of a trial and error in programming the ascent, which is likely going to be the case for any practical use already.

Also, just to see if it can be used for some missions played in first person, I've set this rocket up to have a pilot seat, and when the program finishes, it sets the control-from point back to the command module. So it's entirely possible to use this kind of setup to take you to orbit and let you perform the rest of the mission manually from there. All in all, I'm pretty happy with the result.

[coyotesfrontier]

4 hours ago, K^2 said:

I've seen a number of various approaches to this over the years, from mods either specifically designed to do this or flexible enough to allow for it, like kOS, to really hacky things like simply timing a separatron to tilt the rocket at the right altitude. What I was looking for instead is ability to perform a gradual gravity turn in vanilla KSP, and while I've done some experiments with fins attached to servos, the results have not been very reliable. Recently, I got a thought, what if instead of trying to force the rocket to tilt over, we trick SAS into thinking it already has. So I slapped a probe core onto a servo part, added some curves and activations to a KAL unit, and, well, the results were actually really nice. This can still use a bit of polish, but the entire control unit fits in a single 1.25m service bay and can be tuned for whatever rocket you want to send to orbit.

 

I have found some interesting gremlins while working on this. It looks like the engine gimbals don't want to play nice with SAS if the axis the engine is aligned with differs wildly from the orientation of the control-from point. This isn't causing any issues during the first stage operation, but I had to shut down the gimbal on second stage and rely on reaction wheels only, because if I didn't, the second stage would spin wildly out of control the moment it ignited. There are also problems inherent to SAS use, like the fact that the lock orientation can drift over time, and that is definitely the case here, and you have to compensate for it. However, all that really means is that there is a bit of a trial and error in programming the ascent, which is likely going to be the case for any practical use already.

Also, just to see if it can be used for some missions played in first person, I've set this rocket up to have a pilot seat, and when the program finishes, it sets the control-from point back to the command module. So it's entirely possible to use this kind of setup to take you to orbit and let you perform the rest of the mission manually from there. All in all, I'm pretty happy with the result.

He returns! We were getting really worried about you.