Rockets keep tipping

[spitandpolished]

I've been playing KSP for quite a while, and since the latest update I keep having a problem with my rockets tipping over mid flight.

Typically around 15,000 meters (regardless of whether i have began to turn or not) my rockets begin to tilt, at first enough to compensate with gimbaled engines and or reaction wheels, but then it gets more and more aggresive until its uncontrollable and literally spinning. Sometimes if I ditch my boosters or go to the next stage i will regain control, but obviously this is wasteful and no good.

Ive tried adding fins for drag at the bottom of the rocket and for the torque of having a control surface at the far end, but this doesnt help much.

So what's the problem, are my rockets too top heavy? is it something to do with too much drag?

Why would any of that cause a rocket to spin when you have enough thrust?

[ghpstage]

Your best bet would be to post a picture, otherwise any suggestions will be little more than stabs in the dark.

If I had to guess as to the cause, based on the spinning happening at 16km when travelling vertical I would suspect it was caused by the Centre of Mass (which tends to move downward during flight) dropping below the Centre of Drag (which is unfortunately not visible ingame). A solution to whch may be to add more fins to the bottom.

[Dont]

1. Post a picture. 2. TLDR but I bet you don't have many fins. :D New system changed alot especially the aero science.

[Duke Flapjack]

Fins aren't going to do as much good above 15k meters. A side effect of the new aero model. Try using a reacion wheel or use radial gimbled rockets. The Tantares mod (I think) has a teeny-tiny radial liquid rocket that is designed soely for steering. I use it all the time and rarely have a soumersaulting rocket (although I used to all the time as well).

Basically, you don't have ENOUGH gimbal/reaction to overcome the movement of your ship's mass. It's probably a large rocket, no?

[spitandpolished]

Originally posted by captainradish:

Fins aren't going to do as much good above 15k meters. A side effect of the new aero model. Try using a reacion wheel or use radial gimbled rockets. The Tantares mod (I think) has a teeny-tiny radial liquid rocket that is designed soely for steering. I use it all the time and rarely have a soumersaulting rocket (although I used to all the time as well).

Basically, you don't have ENOUGH gimbal/reaction to overcome the movement of your ship's mass. It's probably a large rocket, no?

I'd say medium sized. I was thinking, since i had fairly large payload that it was too top heavy which didn't seem to make sense, but maybe it was too bottom heavy, I'll try to split the stages up more and see if that helps.

[spitandpolished]

Originally posted by ghpstage:

Your best bet would be to post a picture, otherwise any suggestions will be little more than stabs in the dark.

If I had to guess as to the cause, based on the spinning happening at 16km when travelling vertical I would suspect it was caused by the Centre of Mass (which tends to move downward during flight) dropping below the Centre of Drag (which is unfortunately not visible ingame). A solution to whch may be to add more fins to the bottom.

Thats so stupid (not you or what you're saying). If its going vertical and has reasonable rcs and reaction wheel and all why should it tip.

Does this fall into the category of the wonky new aerodynamics, or is this actually a realistic new difficulty to adapt to --- my intuition says the its the crappy aerodynamics.

[IronSides]

Originally posted by spitandpolished:

Originally posted by ghpstage:

Your best bet would be to post a picture, otherwise any suggestions will be little more than stabs in the dark.

If I had to guess as to the cause, based on the spinning happening at 16km when travelling vertical I would suspect it was caused by the Centre of Mass (which tends to move downward during flight) dropping below the Centre of Drag (which is unfortunately not visible ingame). A solution to whch may be to add more fins to the bottom.

Thats so stupid (not you or what you're saying). If its going vertical and has reasonable rcs and reaction wheel and all why should it tip.

Does this fall into the category of the wonky new aerodynamics, or is this actually a realistic new difficulty to adapt to --- my intuition says the its the crappy aerodynamics.

its def you just saying I have launched a tiny career starting rocket all the way up to one with a 60 ton payload so far no issues what so ever.

[OrangeGills]

https://www.youtube.com/watch?v=_q_8TO4Ag0E

[Duke Flapjack]

One thing I have discovered is that no matter how powerful a rocket is, if it is narrower than your payload it will not work very well.

[Nellvan]

Originally posted by spitandpolished:

Thats so stupid (not you or what you're saying). If its going vertical and has reasonable rcs and reaction wheel and all why should it tip.

Does this fall into the category of the wonky new aerodynamics, or is this actually a realistic new difficulty to adapt to --- my intuition says the its the crappy aerodynamics.

It is more realistic then before. If you got too much drag on the tip of the rocket, it will get thrown around as soon as it goes just a bit off the straight line, it's like trying to shoot an arrow backwards.

Payloads that are wider than the rocket can work really well, but they need to be as a smooth as possible. Use service bays to put stuff into them instead of having it on the hull, or just cover the wohle thing with a fairing.

[=M$= Oroberus]

Just as in real life, by accelerating in athmosphere, you'll hit a point (based on speed and athmospheric pressure/density) where air becomes just like a wall that you have to push trough. This will lead your rocket to seek the way of the least resistance, what usually leads to tipping over. You can counter this in a few different ways:

1. better aerodynamic design
2. more SAS
3. changing angle of impact (before the impact happens)
4. lower your m/s²

Especially #4 is a very easy way to keep your rocket stable. You find that you're hitting this "wall" at 9.000m with 400m/s? Well, lower your accelleration, you could throttle down your engine, or even limit the thrust of your engines until you're a bit higher and the athmospheric density is lowering.

It does not matter how much speed you can build up within the athmosphere, in fact, the more you cut back without getting negativ dV, the more dV you will have left as soon as you hit space, because you used lesser fuel while you were facing athmospheric pressure.

In generall I try to not exceed 500m/s as long as I've not reached at least 35.000m and have come to the conclusion that by doing so, I'm using way less fuel, face lesser tipping and gain a lot of stability in flight. Also this makes your trips cheaper as you may even find that you can cut one of those fuel tanks.

[moriak]

It could also be a bug. Try to build the same rocket from scratch to see if it behaves the same.

[Moleculor]

Okay.

First, realize that the old method of flying is bad and wrong. The old "push through the atmosoup until you hit 10k and then tilt right 45 degrees" method is bad and wrong.

The reason that used to be the way to do it was because the atmosphere in KSP 0.90 was bad and wrong. The lower atmosphere was *far* too thick so it made sense to get through it as fast as possible, and air itself didn't affect the rocket based on how it was shaped, but instead just based on the 'stats' of the rocket.

The new system actually quasi-models real-life air. So going straight up to 10k (at which point you're likely flying 900MPH) and then tilting hard-right is going to essentially slam a wall of air into the side of your rocket at 900MPH, all while the back end is 'pushing up'.

This will inevitably flip your rocket.

The solution for this is to start SLOWLY turning your rocket the moment you lift off. A degree or three at a time. Slowly. Basically try not to leave the prograde circle.

Secondly, make your rockets top-heavy (like a throwing dart), sleek (like a throwing dart) and slap some fins on the back if you're still struggling (like a throwing dart). Top heavy means the pivot point (center of mass) of your rocket will be near the top, which means the vast majority of the rocket will actually be a large amount of space along the bottom edge. The more 'edge' you have there for wind to push against, the more likely it will be pushed back into a stable orientation.

Third, I suspect engine gimballing is a bit over-corrective at the moment. If you're wobbling, wiggling, or otherwise oscillating a lot, try turning off engine gimbals.

[spitandpolished]

Ok, Thanks everybody. I suspect I mostly underestimated the realism really of the new aerodynamics engine, i have a feeling that reducing drag might just be the key.