[Fixed] My rocket keeps on tipping over (Please help)

[B0lt]

Im currently running a 1.5x rescale career mode and my rocket is tipping over almost right after launch. I dont have any videos but almost as soon as the rocket launches the prograde marker tips east word and inevitably crashes if there are any design tips/flaws you guys find please tell me your help would be greatly appreciated

 

 

 

 

Edited September 12, 2024 by B0lt

[Vanamonde]

I'm not familiar with some of those modded parts but I think you need more steering control. Can you replace the fins with pivoting types? And the engine with one that gimbals? 

[B0lt]

The engine has roughly 5 degrees of gimbal and I've used the delta deluxe winglet (which is the only type of wing that I currently have in my career) I dont think control is the issuse

[Tecorian]

Center of weight is nearly in the middle of the rocket.

When burning fuel, the lower part will be lighter than the upper part...

Maybe too much payload?

I would try to attach some thrusters and climb above 20.000 and start then to go with the horizon.

Maybe you can stabilize the flightpath in the thin air better with the thrusters.

 

[B0lt]

Ive thought of doing that but even with boosters the rocket tips over after flight

Guess my rocket is cursed

 

Edited September 11, 2024 by B0lt

[RKunze]

14 hours ago, B0lt said:

Im currently running a 1.5x rescale career mode and my rocket is tipping over almost right after launch. I dont have any videos but almost as soon as the rocket launches the prograde marker tips east word and inevitably crashes

What exactly do you mean with "tipping over"?

1. Does the rocket go out of control and tumbles? or
2. Does the tip of the rocket follow the (surface-)prograde marker, but that marker keeps falling down leading to an eventual crash?

My guess would be 2, because 1 usually means your rocket is aerodynamically unstable, and your design looks OK in that regard (I'd have used a fairing for the payload, but you should probably be able to get to orbit without if you don't go too fast in atmosphere).

If it is 2, then your rocket is actually following the ideal trajectory, a "gravity turn". The only problem is that you start that turn by tipping over too far. From the image, my guess is that your rocket has an initial TWR of well below 2 (which is actually realistic, real launch vehicles usually have a starting TWR of 1.2 to 1.5), which means you need to tip over just a very tiny bit (no more than 2° off vertical, usually less, but that depends on a lot of factors) after the launch, and then just leave the rocket alone.

My usual launch procedure is:

• launch straight up until the rocket is clear of the launch tower and fast enough to be aerodynamically stable (for my designs, 20-30 m/s is usually fast enough)
• tip over very slightly (somewhere between 1° or 2° off vertical, depending on the rocket - as I use kOS to automate my launches, that's actually handled by a script, and the code that calculates how much to tip over is the most complicated bit of that launch script by far)
• keep the rocket pointing prograde (if your rocket is aerodynamically stable, this just means keep your hands off the controls, it will follow prograde automatically)

If you reach apoapsis too soon, retry with a smaller initial tipover.

[Dinlink]

Another possible issue that can be taken care of is a too high TWR while in low atmosphere...

I explain myself: The simplistic Arodynamic center shown in KSP takes in account the center of pressure for ideal lift... But drag is a complex beast... And on flight, if it gets too high can make your rocket tip over (and break it apart if you are using FAR mod) ... That usually happens when TWR goes beyond 2 on the lower atmosphere, making the rocket to speed up dangerously within the thick part of the atmosphere...

Form your screenshot we can observe a 1.7 TWR that can go beyond 3 on vacuum... That indicates that is probable that you're reaching TWR higher than 2 very early on the ascent... So I would recommend to try to throttle down your engine so you start the ascension at about 1.3 TWR and only reache 2 and above where the atmosphere start thinning (between 15 and 30km)

I hope this can help you finding the solution to your issue.

[B0lt]

3 hours ago, RKunze said:

What exactly do you mean with "tipping over"?

1. Does the rocket go out of control and tumbles? or
2. Does the tip of the rocket follow the (surface-)prograde marker, but that marker keeps falling down leading to an eventual crash?

My guess would be 2, because 1 usually means your rocket is aerodynamically unstable, and your design looks OK in that regard (I'd have used a fairing for the payload, but you should probably be able to get to orbit without if you don't go too fast in atmosphere).

If it is 2, then your rocket is actually following the ideal trajectory, a "gravity turn". The only problem is that you start that turn by tipping over too far. From the image, my guess is that your rocket has an initial TWR of well below 2 (which is actually realistic, real launch vehicles usually have a starting TWR of 1.2 to 1.5), which means you need to tip over just a very tiny bit (no more than 2° off vertical, usually less, but that depends on a lot of factors) after the launch, and then just leave the rocket alone.

My usual launch procedure is:

• launch straight up until the rocket is clear of the launch tower and fast enough to be aerodynamically stable (for my designs, 20-30 m/s is usually fast enough)
• tip over very slightly (somewhere between 1° or 2° off vertical, depending on the rocket - as I use kOS to automate my launches, that's actually handled by a script, and the code that calculates how much to tip over is the most complicated bit of that launch script by far)
• keep the rocket pointing prograde (if your rocket is aerodynamically stable, this just means keep your hands off the controls, it will follow prograde automatically)

If you reach apoapsis too soon, retry with a smaller initial tipover.

Yes the issue is #2 but the prograde marker moves without any input 

[B0lt]

I would like to thank every one who commented on this post your help means alot to me and after reviewing the design I was able to send my CubeSat to orbit