hellix08

@Spricigo That was very very impressive indeed

It did that with no SAS ? No roll at all, perfectly stable? This way of launching rockets with no gimbal or control surfaces seems quite interesting but I'll also have to look into using SAS following prograde to do a gravity turn. They both seem very interesting.

Thank you again so much for taking the time to reply @SPACE-MAN @bewing @OHara @Streetwind @AHHans @jimmymcgoochie I really do appreciate it. I'll probably have to come back and read this thread a lot more times, the information you've provided is gold to me at this stage. I've redesigned my rocket to carry the same payload and here's the result (testing in sandbox but will launch in career so I only used the parts that I have available there): Maybe it's not perfect but I think it's already somewhat before than before! It took some time to learn how to fly properly with a good ascent curve but I think it is pretty stable. I used SAS only until I got to 100m/s. After that I used ALT+W to turn steadily, I planned on reaching 45° at 10.000m. I really wanted to use SAS but I don't know how else to do a smooth ascent trajectory other that using ALT+W and leaving SAS off. It took the first stage + 15s burn time of the upper stage to reach a 70.000m orbit. I think that might be enough to put into a Mun orbit (my objective) and maybe even come back and land if I wanted? Your suggestions were great and I tried to remember and apply as many of them as possible so here's what I did to design this new rocket: I tried making the rocket taller and slimmer I removed the boosters because they were overkill for the mission and the TWR was too high although I enabled Advanced Tweakables and played around with auto-struts a little bit so next time I need boosters I know one more trick to try out I put the probe and instrumentations inside a service bay to reduce drag at the top I rotated the probe so that pressing W makes the rocket go east I tried bringing the CoL as low as possible with fins and wings (using as few as possible!). I found that no fins at all would make controls too weak. So I went with the smallest and lightest controllable wings I have access to in career mode. I used fuel priority (available with Advanced Tweakables) to make sure the tanks are drained bottom-up to keep the CoM as high and far from the CoL as possible. Also I tried keeping the rocket pointing inside the prograde marker to avoid too much drag. All of this resulted in probably the smoothest and most efficient ascent to orbit I ever did so far (not that I did that many ). I look forward to building a rocket that uses radial boosters to apply more of the theory and the tips you've provided to make the rocket more stable. Thank you all again for the tremendous help!

Thank you all so much for all these replies! They look very promising and helpful. I will read everything carefully and try applying what you've suggested as soon as I get home from work!

Hello, there is this issue that I've been trying to solve for like 4 days and I still can't figure out what's wrong with my rocket. It's just a very simple and small rocket but, for some reason, when I launch and start turning east as soon as I hit 100ms/s, it starts rolling and pitching and goes completely off trajectory which is very annoying. I've recorded a short video to better explain my point: https://www.youtube.com/watch?v=MojJDt_Es-k Also here's a link to the .craft: https://mega.nz/file/2JJGxCaT#FyZ2BwMTUfI1BDdeRdthWf3vRTxBAkoL7TyNWoYuHHo I've already asked this question on Reddit before: https://www.reddit.com/r/KerbalAcademy/comments/hcu6q2/why_is_my_rocket_so_unstable_it_starts_rolling/?utm_source=share&utm_medium=web2x They gave me some nice suggestions but none really did explain or provide a solution to my issue. Here's what I've already tried: Disabling SAS Disabling roll control on the wings Adding 6 basic fins along the center core Attaching the wings on the center core instead of the boosters Using 4-way symmetry for the wings Using 3-way symmetry for the wings and the boosters Making sure the engine has gimbal capabilities (is a Swivel and not a Reliant) Using smaller boosters (Hammer) Removing the science parts Removing nose caps Putting the instrumentation and the probe inside a service bay to reduce drag aereodynamics Going full thrust with the engine to make full use of the gimbal potential And a mixture of those. None really worked or improved the stability. I am clueless and desperate. If you have any idea please please write that down :).