Pod

[Bill Miller]

I have a problem with my rockets flipping over during climb. To rule out problems in my design, I have copied rocket designs used in tutorials but still, whilst gently tapping the D key with SAS engaged and pro marker engaged, the rocket flips before even 10 degrees of bank. Any advice:)

[Geonovast]

Moved to Gameplay Questions.

Some screenshots of your rocket would help greatly.

[Fraktal]

You need to check two things here.

1. The fins at the back of your rocket. Are there enough of them and are they low enough? Turn on the center-of-mass and center-of-lift indicators in the VAB (three small buttons on the lower right corner of the part selection pane, above the symmetry toggle; you need the left and right ones). If the blue indicator is above the yellow indicator, you either need more fins or need to place them lower.
2. What exactly is on the very top of the rocket? If the front of the rocket has high drag, it will flip even if you have an absurd number of fins.

Edited June 26, 2020 by Fraktal

[James M]

1) Tall, balanced weight, and draggy parts at the bottom

2) Don't turn over so quickly so you are out of the innermost atmo pressures before hitting max q

3) Slow down?

4) Forgot this one. Don't use the russian pods without a fairing over them. They're ridiculously draggy for no reason. 

Edited June 26, 2020 by James M

[Fraktal]

2 hours ago, James M said:

Don't use the russian pods without a fairing over them. They're ridiculously draggy for no reason. 

Actually, I did quite a bit of experimentation with those recently. They are perfectly usable without a fairing, but you need a very high delta-V on the lower stage in order to hold on to the fins for as long as possible. The rocket won't flip while you have the fins and steer carefully but if you drop them too early, you'll flip even without steering.

[Bill Miller]

Thanks for the input people. This issue had really been spoiling my enjoyment of Kerbal. I will post a picture of my rocket if I can wirk out how.

I do have large fins on the bottom of my rocket but I guess the top is quite bulky with my science stuff, and cabin for tourists, cooling radiators etc. 

I am in career mode so trying to earn money and science to take my career forward. I can get into orbit with small rocket but I need larger rocket to have enough fuel left over to get anywhere.

What I don't understand is why a rocket works for some chap in a tutorial but when I build the same rocket, I have this flipping problem.

Thanks again 

 

 

 

[Spricigo]

11 hours ago, Bill Miller said:

To rule out problems in my design, I have copied rocket designs

Let's hope that is not something with those designs too. 

10 hours ago, Bill Miller said:

whilst gently tapping the D key with SAS engaged and pro marker engaged, the rocket flips before even 10 degrees of bank. Any advice:)

Easier said than done but: You need to stop tapping the D key before you reach the point of no return.

A well designed rocket need just a nudge to follow prograde into orbit, no SAS, no gimbal, no steerable fins. Yet it may still flip if pushed just a fraction of degree more than necessary. So, when you say "the rocket flips before even 10 degrees" I immediately assume you are pushing those rockets way beyond limit of their stability. And while this is generally good advice:

6 hours ago, James M said:

Don't turn over so quickly so you are out of the innermost atmo pressures before hitting max q

I think that is exactly what the OP is doing wrong. Waiting too much to start the gravity turn

If you don't turn soon enough you will need to do it more aggressively, not only making more likely to put the rocket in an unstable attitude but also increasing the risk of flexing and SAS over-correction (which itself can ruin a launch).That is particularly true for rockets with lots of control authority but may also happen with 'sensible' designs. So, as soon as you can give the rocket that small nudge with some reliability its time to start the turn.

 

Anyway, that is assuming there is no design problems or bug. A look at the craft would be nice for check this out.

[Spricigo]

4 hours ago, Bill Miller said:

I am in career mode so trying to earn money and science to take my career forward. I can get into orbit with small rocket

So, consider satellites.  The typical satellite contract offer three times what is needed to build the satellite and launch vehicle in advance and triple of that as rewards, if you have the right parts (namely the ant engine, small tanks and fairing) you can build a standard satellite that can be launched from a hammer SRB and go anywhere in Kerbin SoI with spare fuel for 2 ou 3 "adjust orbit" contracts.

Tourists can give more per trip, once you have a reliable "tour Bus" but satellites are very profitable too.