How to launch a control a liquid rocket?

[sonik]

Hi, I´ve a small problem with the first campaign of the tutorials, the rocket age (yes, I know, the need of help in this early stage it´s a kind of embarrassing).

So... I have the liquid fuel rocket (mk-6XL parachute, RC-001S Remote Guidance Unit, z-500 battery, FL-T400 fuel tank and an LV-T30 engine) and the mission is to lit-off and head eastward but, and here comes the problem, when I try to make a lateral movement (or above 5km) the rocket begin to spin around and it´s out of control. I've try to add some cannards at the bottom but i can do anything.

I know that de simple way is using a SAS but I want to do it without any computer help.

Thanls

[Nasakev]

Is this the tutorial where you have to calm a spinning craft or one of the scenarios?

[Jason Patterson]

Are you spinning like a top (rolling) or flipping end over end?

If it's the former, I don't know what the problem might be. You could have a keybind messed up or if you have a joystick it might be active at the wrong time (check your roll axis instrument to see if it is pegged to one side or the other.)

More likely it's the latter, and it's due to a lack of control in the rocket you've built. You've got a very small probe module for your command module. Without additional help in the form of thrust vectoring, RCS, or control surfaces, it just doesn't have the power to keep the rocket on track. As a result your angle of attack for maneuvering is very limited (or you'll spin out.) You might try using an LV-T45 engine, as that will give you thrust vectoring and much much better control over your rocket. You could also replace the probe (or augment it) with a manned capsule, as those have far greater turning power.

ETA:

I'm assuming you built this rocket yourself, rather than it being supplied by the game. I don't have any tutorials that feature a rocket of the type you describe.

[Horn Brain]

Jason's got it. Put a thrust-vectoring engine on there and you should be fine.

Here's the reason for your problem: Once you get to high altitudes, tail fins and winglets don't have as much authority and all that matters is drag. The parachutes have a higher drag than the other parts, and (with the way the game calculates drag) that means that any vehicle with a parachute on the front is going to have the center of drag ahead of the center of mass, which means it's aerodynamically unstable (it flips over).

[sgt_flyer]

the trick is, at this stage of the campaign, you can only use a LVT 30

one problem with aerodynamically unstable crafts, would be to be more gentle while turning (do not wander too far away from your prograde marker, or your rocket will tumble - typically, high chances of tumbling would be when you go over 20 / 25° away from your prograde marker. - i'd say, just to be safe, while turning, don't move farther than 10° away from your prograde marker - and then let it follow your heading. - don't go directly to a 45° heading, make a nice smooth curve instead (i was testing with a floating beacon carried by LVT30 with winglets at the bottom of the LVT30's FLT800 - the beacon was around 4 tons, with quite a lot of parts , including 4 parachutes and a drogue)

an analogy would be to try to make a sharp 90° turn at high speed with your car - you have all the chance in the world of losing control of it - but if you have a nice long curve to make this 90° turn, you can make this turn with your car easily at high speed

Edited July 2, 2013 by sgt_flyer