Gravity turn problems...

[Alex614]

Hello! So, this may sound nooby or such. However, I have been having problems with rockets that are PERFECTLY stable on ascent. When I start the gravity turn though, even my most perfectly stable ships start tumbling uncontrollably. Not only are these rockets stable, they have worked on previous launches, and now, even if I just nudge the rocket into a slight angle, it falls over and tumbles uncontrollably. Even rockets I have used dozens of times. Anyone else having this issue???

[Giggleplex777]

I have this issue when I use aerospikes. It doesn't seem to happen (at least not often) when I use the LV-T30 though.

[Francesco]

the problem with aerospikes is their low drag (0.1) compared to the other parts - which usually have a drag of 0.2.

they tend to make ships heavy on top.

can you show us your ship, Alex?

[Alex614]

Unfortunately the only screenshots I have are on my steam community page, and when I try to upload them, it uploads the link to all my pics, not that specific one Anyhow, I used to grav-turn at 12 km, now that does not work. Gravity turning around 15-20 km seems to help, but makes orbiting harder

Edited May 16, 2013 by Alex614

[Jason Patterson]

So this isn't a new rocket that is having problems, it's a formerly successful design that is no longer working? If that's the case, then this is a lot weirder than a control problem, assuming it is the exact same vessel.

If it's not the exact same design, you could try using one or more vectoring engines, or perhaps adding control surfaces. Ascending more slowly helps as well, but that's only a solution up to a point.

[Greywind]

I think the problem here is that (if i remember correctly) the aerospike engine does not have any gimbal, as you turn with the torque of the pod, the engine can't compensate. Some control surfaces, or a thrust-vectoring engine should do the trick.

[Kosmo-not]

Your problem is either you have parts with a lower drag coefficient near the bottom of your rocket, or you have winglets or other control surfaces near the top. Either of these will make your ship want to point tail first when you point too far away from your prograde vector. You can still fly your ship to orbit; you just need to start your gravity turn sooner and keep your nose pointed mostly prograde until you get into the upper reaches of the atmosphere.

[RoboRay]

There's not much we can do without some pictures of the ship. Most design problems can be identified in a good screenshot or two, but we're just speculating without them.

[Eric S]

If you've recently installed FAR for more realistic aerodynamics, it can cause this kind of problem, especially if you've got an awkward payload that isn't in a fairing. If you did install FAR, it's important not to be more than about five degrees off of prograde at any time you're in a significant atmosphere.