Ship flies out of control when I try to slightly aim it towards 45 degrees?

[someguy12341234]

As mentioned as the topic, this ship will fly out of control if you slightly try aiming it. At surface level (0-1000) it will not go upwards simply due to not having enough power. So I usually connect it to a Booster to get it up high before flying with the top ship.

That is the setup I'm using, it flies just fine and is able to get the top ship high enough to where it's thrusters are able to have decent speed.

Once the top ship is disconnected, I aim it 45 degrees so I can go horizontally across Kerbin at an altitude of around 15,000. However, when I try pointing it at 45 degrees, the ship will jerk back upwards towards 0 degrees then spiral wildly out of control. I have no idea why!! If I try adjusting for the jerk towards 0 degrees, it'll just jerk downwards past 90 degrees and spiral the same way. It's frustrating but I have no solutions for this!

The only solution I had was to remove the bottom 3 fuel tanks of the top ship, but I want more fuel otherwise the ship won't go far.

Any solutions? Help appreciated.

[capi3101]

Those standard canards are up too high; you need to move them to the outboard stages below the center of mass (lower tanks).

Other things - lose the third FT-800 on the central stack and slap an LV-T45 on the bottom of it, and you should be able to make orbit with what you've got without needing a booster (the canards and the -T45 will give you good steering authority during the launch). Be sure to drag the LV-T45 engine indicator down to the second stage (i.e. set all three engines to fire on launch). Then it's put on a small RCS tank and 4 blocks so you can deorbit the command pod when you're ready; obviously you'll want that above the stack decoupler. You also don't need the Mk-16 XL chute - the standard Mk16 will work just fine; if it's coming off on you and you're losing Kerbals, strut it down.

And make sure to not put your stack decoupler and the chute in the same stage. Odd things can happen, like the chute not deploying when you want it to.

Edited July 25, 2013 by capi3101

[SRV Ron]

Remove the fins completely and shorten the booster with Rockomax fuel tanks. That should help with steering stability. It's going to be uncontrollable wobbly in its current design.

For the example in the top photo, use the smaller parachute, ditch the fins, place LV-30 engines on the outside boosters and a LV-45 on the center, rearrange the fuel lines to feed the center from the outside, and set launch to fire all three engines on launch. Be sure to brace the boosters at the lower end to the center tank.