Why does my rocket just flip

[Scout61699]

Hey there,

So I used to play KSP a lot before, so I know all the controls and the parts and stuff, but I'm having a lot of difficulty just starting out in the new version

I'm trying to start super simple. I've got only the first liquid engine and fuel tanks. My first rocket (well, second Since the first was 1 sold rocket) consists of a parachute on top, a command module, 5 engines, with 2 fuel tanks for each engine. 1 in the middle 4 around it. Oh and nose comes on the outer 4

Every time I get to about 5000 meters the rocket just flips strait over.. I've tried having all the rockets exactly even, tried having them as far down as I can, tried having them up. On all those scenarios I've tried differing throttle levels, from full throttle to 1/3 throttle. No matter what around 5000 meters, it just upends itself. I don't understand what is going on.. I've also tried starting out low and getting faster but to no avail

I'm sure I'm just missing some mechanic or other but I dunno any help appreciated

[Harry Rhodan]

A picture is worth a thousand words (especially one where we also can see your staging setup).

If you are lighting up all those engines at the same time you are severely overpowered and with four nosecones on the same level as your cockpit you also have a lot of drag on the top, which will spike exponentially when you hit Mach 1.

There's also a nice tutorial with pictures explaining the new stuff: http://forum.kerbalspaceprogram.com/threads/117876-Why-Does-My-FLIPing-Rocket-Always-Flip-Over!-%28Easy-Picture-Explanation%29

[viktor19]

Hey there,

So I used to play KSP a lot before, so I know all the controls and the parts and stuff, but I'm having a lot of difficulty just starting out in the new version

I'm trying to start super simple. I've got only the first liquid engine and fuel tanks. My first rocket (well, second Since the first was 1 sold rocket) consists of a parachute on top, a command module, 5 engines, with 2 fuel tanks for each engine. 1 in the middle 4 around it. Oh and nose comes on the outer 4

Every time I get to about 5000 meters the rocket just flips strait over.. I've tried having all the rockets exactly even, tried having them as far down as I can, tried having them up. On all those scenarios I've tried differing throttle levels, from full throttle to 1/3 throttle. No matter what around 5000 meters, it just upends itself. I don't understand what is going on.. I've also tried starting out low and getting faster but to no avail

I'm sure I'm just missing some mechanic or other but I dunno any help appreciated

I noticed that you play KSP for a long time. Most common problem with rockets flipping is that you turn too hard. Usually my rockets have TWR from 1.3 to 1.6. I start my gravity turn early, as soon as my rocket reaches 100 m/s. Then I keep the nose on the edge of prograde vector to about 30 km altitude.

And remember, fins are your friends!

[Sharpy]

Add fins on the bottom. Seriously. I always struggled with rockets flipping over, then I tried one I'd be able to steer better so I added some controllable fins, and... I was unable to turn it horizontal. Seriously, they hold it so firmly up you need a lot of effort to flip it over.

[Warzouz]

If you can't turn after adding some fins, try smaller ones. Winglets are very efficient for small rockets.

Don't forget that heavier rockets are easier to fly than lighter ones. Learning curve can be steep, but then you won't have any problems.

[LordCorwin]

With the latest version I noticed that on first stages of the game it was quite difficult to control de rocket when leaving Kerbin's surface, between 5k and 20k.

I think it is due to the new aerodynamic model.

I solved this using better wings with more lift ratio, activating SAS, adding the stabilizer unit, maintaining the atmospheric performance quite below 100% (seen with Kerbal Engineer mod)... and not starting the orbit maneuver until 20km height. Even then, your maneuvers and corrections must be gentle.

Edited: also, take care of selecting an engine with Gimbal ability

Edited June 13, 2015 by LordCorwin

[cybersol]

You are not alone. This spinning thing is something we all initially had trouble with in the new 1.0+ aero until we learned to engineer and fly new rockets.

Spinning out of control essentially comes down to a contest between drag and control. When the drag overcomes your control authority, you go for a spin. You can decrease drag by staying closer to prograde and building a more aerodynamic rocket. You can increase control using engine gimbals, stabilizer wheels, and control fins (like AV-R8).

Also note that drag increases significantly right around mach one (340 m/s), so you should stay pointed as prograde as possible at speeds around 290-400 m/s.

On a rocket, any control fins should be as low and outside as possible. If you are using control fins on more than one stage, the CoL needs to stay below the CoM at all times, even as the tanks empty.

[Scout61699]

Thanks for all the replies guys!! I took off the outer 4 engines and went to a single column rocket, to which fins magically solved all my problems!

Since then I've been experimenting more, and I've found the solid fuel boosters have no issues! I put on 4 of those big tall 6Ton bad boys around the outside of my liquid fuel engin and I can actually make it to 100,000 km quite easily.

Its only when when I switch to loquid engines I have this problem.. I made the stupidest looking rocket with the first available solid fuel booster.. I out 4 on the outside of my liquid engine, and I put 4 more on the outside of that, so I basically looked like a cross with 5 engines across both ways (2 solids, liquid, 2 solids) and then the same the other way.. So in all 8 solid boosters and 1 central liquid... This thing flew like a beast!! If I tried to switch them all to liquid it went no where... Why the difference?

[cybersol]

Hard to say for sure without pictures. Larger rockets are easier to control because all the stacks help keep the rocket stable in the direction of the airflow. If you are using multiple stacked tanks in you LFO rockets, then the top tanks use fuel first. This causes your center of mass to get lower over time. When you CoM goes behind your center of pressure, then your rocket want to flip. However solids use one big tank, so they don't have the shifting CoM.

[AlextheBodacious]

Hard to say for sure without pictures. Larger rockets are easier to control because all the stacks help keep the rocket stable in the direction of the airflow. If you are using multiple stacked tanks in you LFO rockets, then the top tanks use fuel first. This causes your center of mass to get lower over time. When you CoM goes behind your center of pressure, then your rocket want to flip. However solids use one big tank, so they don't have the shifting CoM.

I hate it when people don't read the post above.

[Starwaster]

I hate it when people don't read the post above.

I concur. I hate that too.

Let's take a look at the last TWO posts before yours.

Thanks for all the replies guys!! I took off the outer 4 engines and went to a single column rocket, to which fins magically solved all my problems!

Since then I've been experimenting more, and I've found the solid fuel boosters have no issues! I put on 4 of those big tall 6Ton bad boys around the outside of my liquid fuel engin and I can actually make it to 100,000 km quite easily.

Its only when when I switch to loquid engines I have this problem.. I made the stupidest looking rocket with the first available solid fuel booster.. I out 4 on the outside of my liquid engine, and I put 4 more on the outside of that, so I basically looked like a cross with 5 engines across both ways (2 solids, liquid, 2 solids) and then the same the other way.. So in all 8 solid boosters and 1 central liquid... This thing flew like a beast!! If I tried to switch them all to liquid it went no where... Why the difference?

Hard to say for sure without pictures. Larger rockets are easier to control because all the stacks help keep the rocket stable in the direction of the airflow. If you are using multiple stacked tanks in you LFO rockets, then the top tanks use fuel first. This causes your center of mass to get lower over time. When you CoM goes behind your center of pressure, then your rocket want to flip. However solids use one big tank, so they don't have the shifting CoM.

Note how Scout61699's post ends in a question? cybersol then tries to ANSWER that question.

Do you see how this works?