veering off course in orbit

[endl]

so im trying to change my AP/PE to higher orbit for planetary transfer, i started the burn with mech jeb and the rocket starts to wobble heavily and drifts quickly away from the node. maybe its my design. i was told that pulling is better while in orbit. is it too many engines?

Edited September 26, 2014 by endl

[Franklin]

You have pushing engines on that thing, too. have you tried the maneuver with them instead to see if it still moves off node? If not, it's your design.

[Pecan]

Two things -

1) Pulling engines, ahead of the CoM need to have gimballing disabled or they tend to adjust the wrong way and make steering discrepancies and wobble worse.

2) You have more engines at the front than rear and it looks like the exhaust from 'some' will hit the rear ones. Not only could that make things blow up but it also blocks the affected engines, resulting in uneven thrust turning the rocket.

[endl]

those engines were disabled during the burn

no i have not

i would prefer to use the nukes this is supposed to be a long range mission i dont want to waste fuel.

what exactly is the cause? if its too much engine power how can i figure out exactly how much i need?

how exactly is my thrust at the front being blocked? stuff getting too hot i get (rear engines were off) stuff being burned off i get, but thrust being blocked sounds off

Edited September 26, 2014 by endl

[Rhomphaia]

while pulling is better (for non rigid rockets), the problem in KSP used to be that gimballing engines ahead of the center of mass would gimbal in the wrong direction.

I know 0.24 improved engine gimbals but I am not sure if it fixed this. but since the gimbals seem to be your only real control authority it could be the problem

[mhoram]

Pulling engines use the same gimbaling as pushing engines.

This means that they steer the rocket in the opposite direction of the intended one.

Try to "toggle gimbal" in the context menu of the nukes to switch gimbaling off.

If you have enough Torque, you should be fine.

[Pecan]

If the exhaust of the front engines is hitting the ship its only effect is to 'stretch' the ship - front pushing against back - so there is no net thrust. The physics is rather different but think about a car; tyres push road = good, tyres push another part of the car = bad.

[endl]

it was the gimbals ty everyone