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What I am doing wrong in building my rockets?


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Ok, so I havebeen trying to get a rocket that will do a nice gravity turn for ages and generally settle for building something like this to reliably reach orbit:

screenshot0.png

Ok, here was my latest attempt:

screenshot16.png

WTF! Why cannot I not get my center of lift anywhere near my center of mass? This typically causes all sorts of spectacular flip floping space ship wrecking mayhem.

Edited by hansman1982
Changed to question.
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Worrying about center of mass vs center of lift is a problem for aircraft. Pure rockets can ignore it -- just keep any fins near the bottom of the stack.

Edit: 463 m/s at ~6.2 km? Try throttling down a bit?

Edited by UmbralRaptor
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Worrying about center of mass vs center of lift is a problem for aircraft. Pure rockets can ignore it -- just keep any fins near the bottom of the stack.

Edit: 463 m/s at ~6.2 km? Try throttling down a bit?

I guess I get frustrated that the pre-created rockets have them very close, and I've been told it's part of the problem.

also:

MechJeb + FAR...

I will try smaller engines...

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Ack, I missed that it was FAR. (I stick with the stock aerodynamics) Rather high speeds at low altitudes is reasonable then.

Ya, FAR is on it's last legs here. It's nice that it is easier to launch into orbit but I can't even do a 5km-200km gravity turn set at 100% turn shape without the aerodynamics "staging my rocket" for me.

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I had a problem like this a long time back, but I think my problem was the opposite.

So, what's exactly happening during launch? Is the rocket flipping over either before or during your gravity turn or is it refusing to turn at all?

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Hum, you really don't need to bother with your center of lift with rockets. And your problem is FAR. MechJeb just can't handle things correctly with FAR. Really you just have to make a choice: MechJeb or FAR. Until the creator of Boths try to make a compatible version for each other (which would probably the greatest thing ever), you can't use both without one flipping everything off course. If you decide to keep FAR, just make your gravity turns very, very, very slowly. Else dreag will you set you off course. Else if you keep Mechjeb, just have it do your gravity turn from 10 to 70km, with 40-70% and it will go great. But seriously don't take care of your center of lift with a rocket.

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your TWR on liftoff is way too high for a winged payload (if you use one) even for a non winged payload, it's still too high :) - use a reduced throttle at liftoff to prevent the wings your payload carry to generate lift by climbing too fast - i had the same problem with my kliper on the onega's second version. basically, the higher you go, the speedier you can go, because it requires more speed to generate winglift. (on my onega's second version , i usually go full throttle after the boosters separation) plus, add some stabilizers wings (with control surfaces) at the bottom of your rocket - this will lower a bit the center of lift.

Edited by sgt_flyer
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I was even having problems with >1.5 TWR on my rockets. I really do think the problem was MechJeb + FAR. I removed FAR and managed to complete even the most wacky of gravity turns with ease.

To the problem, it was that once the rocket began the gravity turn it would tumble out of control and generally shred the rocket.

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I was even having problems with >1.5 TWR on my rockets. I really do think the problem was MechJeb + FAR. I removed FAR and managed to complete even the most wacky of gravity turns with ease.

To the problem, it was that once the rocket began the gravity turn it would tumble out of control and generally shred the rocket.

FAR requires very, very, verryyyyyy slow gravity turns. Else the drag model makes it flip out.

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