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Szkeptik

Every rocket flipping out arund 9 or 10 km

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Doesn't matter how the craft looks or how fast it's moving or if it has sas or if it has fins anywhere. Around that height it just randomly starts to pivot in a seemingly random direction and it starts doing flips. Sometimes I can stabilize it sometimes it just doesn't respond to anything. Reaction wheels don't seem to help one bit.

Edited by Szkeptik

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Speed is critical for the first 20,000 meters. So is turning too fast at the lower elevations while traveling fast. Both will cause a flip out as the nose of your craft rapidly picks up drag as the rest of the ship is now sheltered from those forces.

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I'm not turning anywhere. The craft is stable going straight up until the 9-10 km mark, and then it just flips around uncontrollably in a random direction. I even had a not perfectly balanced craft (radial parachute and antenna on one side) flip over towards a DIFFERENT side than the overweight.

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You are going too fast, even after the previously mentioned 20km if you tilt too much away from prograde your rocket will flip.

The smaller rocket fins will help (fins are currently bugged though), but you will need a gimballed engines or your rocket will still be unstable.

Try not to veer too far from prograde. Even with a gimballed engine the ship will flip if your ship gets out of the prograde circle while below 15km and above 400m/s.

Finally, if you are going faster than 400m/s by 10km, you are definitely going too fast.

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Wow, I must do everything wrong. I'm gonna have to slow down too. But my rockets don't flip out anymore, fixed it with fins.

Try not to veer too far from prograde. Even with a gimballed engine the ship will flip if your ship gets out of the prograde circle while below 15km and above 400m/s. Finally, if you are going faster than 400m/s by 10km, you are definitely going too fast.

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Pictures of your ship would be nice.

You can run into this kind of trouble if you go too fast and your center of mass is behind your center of pressure. As a design principle you'd like to have the weight at the top of the rocket, which is hard to do because fuel drains from the top. Use the biggest tanks you can and/or add stages, slow down, fly as close to prograde as you can, and if that doesn't do it add fins.

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Wow, I must do everything wrong. I'm gonna have to slow down too. But my rockets don't flip out anymore, fixed it with fins.

Haha, I was thinking the same thing. Plus going faster seems to save dV, in moderation.

For the OP, you basically need to use some plane concepts to build better rockets in 1.0+. You'll want a center of lift behind your center of mass, even as your tanks empty. More, lower fins with more lift will make you more stable. However, then you will need more control authority to turn (canards/winglets/etc). As a compromise, I find the small delta control surfaces to be good for small-medium sized rocket fins.

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With the current gimbal implementation, it can help to steer and to stay on course, but it can also induce flipping, because every gimbal movement of the engine makes it's thrust deviate from the ideal centre of mass / centre of thrust line.

I would recommend limiting the gimbal and working with aerodynamic controls instead if possible. When correcting the course, the ungimbaled engine still thrusts through the centre of mass and doesn't induce a snowballing effect for flipping.

However, you could even do a little trick if you have multiple tanks in a row. Then you can disable the fuel feed for the upper fuel tanks, moving the centre of mass up during ascent. This reduces flipping dangers, too. However, you must manually (or by action group) reenable the fuel feed once the lower tanks are empty.

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Keep on trying. I struggled a lot at first, then finally found how to do it.

Event my lightest rocket was flipping. Now I have a steady small rocket (I don't event touch the steering).

Heavier rockets seem to be easy to take to orbit. They are more forgiving in angle of attack.

Don't use SAS except when rocket goes slightly off course (usually on tacke-off)

As many have told : add fins far back then try and retry. Try different thrust limitation on boosters.

MJ is no helping a lot. You must ensure the rocket to fly manually before attempting to use MJ.

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Depends on the craft I think. Usually this happens to me when I lean into the orbit if the rocket is too heavy in either end. If you don`t use fins this will often lead to control issues until you get high enough. Also the nose will tend to drop if you`re too slow or refuse to come down if you`re too fast. If you go much too fast you`ll tend to get gyrations, especially on long ships. If you use too many boosters from 0-10 000m you get trouble. If that`s the case try staging them so one half of them fire when the first half is done. Remember to stage ditching the spent ones at the same time as the second battery fires though. If you get sonic visual effects around the craft that`s fine. but you`re not supposed to get heating effects because that means you`re losing momentum to the air resistance and are wasting fuel and thrust you should be using to get into orbit. It looks cool but it`s a sign that you should stage your boosters to lower your speed below 10 000 meters and increase it above 10 000 meters.71pxk0.png

Edited by Fishslap

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What else may help you is to manually manage the fuel flow... For anything under 10mT payload in my career save I'm using a rocket SSTO to maximise my funds efficiency. To avoid the 9km spinny fun times which it will do even with fins, disable the tanks higher up (click the little Green triangles and turn them into Red "No entry" signs), and let the fuel drain from the lower tanks first. Then enable the next tank as the lower one is about to become depleted. This way it'll keep your CoM nearer to where it was when you built the thing in the VAB. A bit cheaty? Maybe...?

Using the above, you may not even need to use fins (assuming you have a gimbal engine - which if you're SSTOing seems a given, to me at least). Warranty void if attempted without fins. No guarantees that above and aforementioned will prevent catastrophic failures due to pilot error.

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