Staging Controls For Multi-Part Landers/Ships Messed Up?

[Guest LTrotsky]

Question : Why does initiating a stage not activate engines after a ship has been assembled in space?

Situation : It was necessary to build a ship out of several assemblies in orbit around Kerbin, the two main stages being a "Mothership" and an Eve Lander. Each of these assemblies were constructed in the VAB separately, saved as a sub-assembly, and then separately launched into LKO, where they were put together for an Eve Mission. Eve landers have to pretty massive, and while it may have been possible to launch the entire ship in one piece from Kerbin's surface, it seemed a bit unrealistic and more challenging to assemble the ship in space. Also, launching a craft from the surface of that size, with that many parts, seemed outside the scope of my present skill. In any case, the ship was assembled, sent to Eve, and the Lander touched down with almost full fuel tanks (as intended).

Above Eve, the Lander stages have to be re-ordered to the configuration they were originally constructed with, as the joining of the Lander to the MS seems to automatically re-order the stages (and gets it wrong, of course - joining activations that shouldn't be joined, etc.)

The Lander is an asparagus staged assembly, with two large tanks with 1 Mainsail each, while the lander core contains a half-sized Rockomax tank and 4 Toroidal aerospikes. The intent is to use the Mainsails to clear most of the atmosphere and pressure, then separate those heavy tanks and engines and fire the Lander core to achieve orbit and rendezvous with the MS. The critical part of the launch from Eve is this separation of the two Mainsail/heavy tank assemblies from the core, and a simultaneous fire of the Lander core with the 4 Aerospike engines. Problem is : When I activate this stage - which fires some solid separation rockets, the radial separators of the Mainsail units, and initiates the fire of the toroidal aerospikes, the latter do not fire up and can only, it seems, be fired up manually with the right-click, activate engine commands. This means the craft cannot make orbit - the Lander core aerospike engines if activated manually throw the craft into a spin, while if I throttle down and do the activation too much momentum is lost (the craft isn't 'overengineered' for the Eve landing - it was a minimal design and worked under test conditions on Kerbin).

Is this a limitation of the sim?

Edited May 13, 2014 by LTrotsky

[Pecan]

Can't give you an answer to your question but, possibly, a solution to your problem.

Install the Action Groups Extended (AGX) mod. This lets you create and edit action groups (up to 250!) in flight. Using this you should be able to put all the required engines, decouplers, separatrons, etc. into a single action group and at least fire them that way rather than having to right-click each component in turn.

[Guest LTrotsky]

Can't give you an answer to your question but, possibly, a solution to your problem.

Install the Action Groups Extended (AGX) mod. This lets you create and edit action groups (up to 250!) in flight. Using this you should be able to put all the required engines, decouplers, separatrons, etc. into a single action group and at least fire them that way rather than having to right-click each component in turn.

Thanks - I rather expected there would be a mod, but I play strictly stock. If I take your answer correctly, it also means that, yes, this is a sim limitation = when you have to re-order staging elements in flight, the engines will no longer activate automatically when staged. Is that right?

[Taki117]

Thanks - I rather expected there would be a mod, but I play strictly stock. If I take your answer correctly, it also means that, yes, this is a sim limitation = when you have to re-order staging elements in flight, the engines will no longer activate automatically when staged. Is that right?

If they are all in the same stage they should still activate at the same time, even if they were reordered. If they were active, then shut down (Either manually or with action groups) Then I do not believe they can be staged again.

[Guest LTrotsky]

If they are all in the same stage they should still activate at the same time, even if they were reordered. If they were active, then shut down (Either manually or with action groups) Then I do not believe they can be staged again.

Okay. I was about half-aware of this problem and made sure that the lander when built had exactly correct staging - but since that craft was put into LKO I've sent up 2 different MS assemblies (the first one had too little RCS). So, the Lander itself was attached to an MS when launched, but then a new MS was sent up and attached. Somehow in this process the auto-activation of the Lander's staging got borked.

[Taki117]

Okay. I was about half-aware of this problem and made sure that the lander when built had exactly correct staging - but since that craft was put into LKO I've sent up 2 different MS assemblies (the first one had too little RCS). So, the Lander itself was attached to an MS when launched, but then a new MS was sent up and attached. Somehow in this process the auto-activation of the Lander's staging got borked.

To check which engine goes with what stage (After the borking) simply hover over the engine in question, and then see which icon highlights. Make sure they are all on the same stage and it should work.

[Pecan]

To agree with Taki - it "should" work, otherwise docking/undocking would always kill any staging. Action groups are much more flexible and reliable though.