Alright I'm stumped... abort system

[Renaissance0321]

So I've been trying to design an abort system and I want the radial decouplers to pop the engines off, the liquid engine to shut down, the stack decoupler to pop my pod off the top and deploy a parachute. So far the only thing that happens is my pod pops off and deploys parachute but the engines don't shut down or pop off so it's pretty catastrophic. Any ideas what I'm doing wrong? Here's a picture...

[Jordanpumah]

you can't turn SRBs off when they are ignited, If you must use SRBs, use separatrons to push them away from your craft while they are still on.

[Renaissance0321]

No they're not even decoupling...

[Taki117]

Try moving your pod decoupling to the bottom of the stack. If I am thinking correctly it goes in the order of the stack, so what's happening is your chute is deploying, your pod is popping off, and then none of the other commands are getting to the rest of your ship.

[Dangerous_Beans]

i think Taki117 has it.

so currently the games goes: deploy parachutes, check; stack decoupler, check; shutdown engine, not attached; radial decouplers; not attached.

i would do: liquid engine shutdown, radial decouplers, stack decoupler. parachutes as manual.

[SRV Ron]

No they're not even decoupling...

Thats because they have failed to fasten to them. When properly mounted, there will be a larger gap that, when the decoupler is selected, the booster will be part of it. It is a common problem we have all faced. The decouplers stage, but the boosters remain attached.

Try removing the boosters and reattaching them to the radical decouplers until you get a bigger gap.

For an abort, you will not be able to do so while the SRBs are fired. They are likely to destroy the rocket if staged before burning out. Otherwise, you can always abort by hitting x to shut off the engine, then stage to eject the capsule and wait until you are dropping back to Kerban before deploying the parachute so you don't lose it.

Edited October 24, 2013 by SRV Ron

[SRV Ron]

Try moving your pod decoupling to the bottom of the stack. If I am thinking correctly it goes in the order of the stack, so what's happening is your chute is deploying, your pod is popping off, and then none of the other commands are getting to the rest of your ship.

According to the staging column, they are in the correct location. The problem is that the SRBs didn't connect to them.

[Renaissance0321]

Try moving your pod decoupling to the bottom of the stack. If I am thinking correctly it goes in the order of the stack, so what's happening is your chute is deploying, your pod is popping off, and then none of the other commands are getting to the rest of your ship.

I thought that might be the problem? But how do I change the order of the stack?

Also the boosters are fastened correctly because when I go to the next stage it works properly. Just the abort isn't working.

[RocketPilot573]

To me it looks like the boosters aren't even attached to the decoupler...

[HeadHunter67]

When properly mounted, there will be a larger gap that, when the decoupler is selected, the booster will be part of it. It is a common problem we have all faced. Try removing the boosters and reattaching them to the radical decouplers until you get a bigger gap.

This is the correct answer.

[AlamoVampire]

Renaissance: this may sound stupid, but, have you tried setting all the things you want to happen in your abort action group? each decoupler, each parachute and so on? also, are you hitting the abort button on the altimeter on top of the screen or hitting BACKSPACE?

[Renaissance0321]

Renaissance: this may sound stupid, but, have you tried setting all the things you want to happen in your abort action group? each decoupler, each parachute and so on? also, are you hitting the abort button on the altimeter on top of the screen or hitting BACKSPACE?

No I just click on one but it highlights all 3 and I'm using backspace

[Renaissance0321]

This is the correct answer.

You can see here they are properly fastened (they are the tt-38k decouplers which are close) and here they are in action successfully decoupling...

[deepspacecreeper]

i think the abort action group shouldn't activate the parachutes. instead put three sepratrons on the pod itself and activate them during the abort system activation, so the pod will be pulled from the rocket. decoupling the boosters is not a good idea. also i recommend u to put custom action group 10 for deploying the parachute so you won't have to go through the stages.

[AlamoVampire]

I built the same ship you have posted, well, almost the same, I do not have the kerbal engineer, but otherwise, same ship, set up the same as well. abort sequence and action group as well. I saw something peculiar when I tested it. The TR-18 stack decoupler worked, as did the MK-16 parachute on multiple tests, but, the TT-38K radials did NOT decouple. They stayed with the rocket. I did not experience the catastrophic explosion you show, but, in my last test, the one in which I photographed for my response, I lost my chute from the G Forces involved. I would recommend using sepratrons to shove the capsule in some direction away from the body of the craft.

I have tried this for you in many configurations, with sepratrons. However, it is my conclusion, that this setup, while a GOOD lifting setup, has inherent fatal flaws to the capsule. Even with Sepratrons on the capsule, the failure of the abort sequence <on all stock decouplers> to cut the boosters off this particular rocket during abort sequences is ultimately fatal to the occupant. I do not know why this is so, as with OUT them, the capsule comes off just fine, save for the loss of a parachute on my test at least. There IS something inherently fatal in this design when sepratrons are included in the mix, while in flight. An abort FROM the launch pad, however, is completely safe, as you see in one the of the below pictures. I wish you the best of luck in all your space adventures.

Below are the pictures:

[HeadHunter67]

You can see here they are properly fastened (they are the tt-38k decouplers which are close) and here they are in action successfully decoupling...

...and, I can see in the first pic that they were not fastened in that fashion, but rather snug against the hull. It looks to me like you have found your answer, as I suspected.

[stupid_chris]

...and, I can see in the first pic that they were not fastened in that fashion, but rather snug against the hull. It looks to me like you have found your answer, as I suspected.

I think the confusion from the last picture comes from the fact that the RT-10s are mounted in triple symmetry, but the camera angle makes it look as if they were only a pair. So they end up looking as if they were attached to the hull.

Anyway, to address the problem, I think it's coming from the decoupling and action grouping logic. The pod will end up detaching first and when it issues the command to separate the radial decouplers, the pod is already detached and can't connect with them anymore. The only workaround I can see for now is to use two different action groups., the first to stop the engines and decouple the SRBs, the second to decouple the pod. I'd activate the parachute manually once you clear the ship to prevent colliding with the debris though.

[kurja]

...and, I can see in the first pic that they were not fastened in that fashion, but rather snug against the hull. It looks to me like you have found your answer, as I suspected.

I don't think that's the case, it kinda looks like they're against the hull but there are 3 of them, one hidden behind the center stack in that first pic, try it yourself and that's how they look like when properly attached...

[HeadHunter67]

Not sure what to say, then. I've often used other commands in an abort sequence, such as shutting down liquid engines, and I have never had a problem with them not being issued. Understandably, you can't stop an SRB from burning, but if it doesn't work, then do as Chris suggested and make their decouplers a separate action group.

Just be warned that an unattached SRB can still be a risk, because it's going to keep on burning - only now, in a not-entirely predictable direction.

[AlamoVampire]

it should be noted that the TT-38's are a THIN decoupler, and can cause it to look like an SRB is stuck directly to the body of said rocket.

[Renaissance0321]

Well I think ultimately what's going on here is the abort sequence is causing my command pod to decouple first and not allowing any other commands to the rest of the stuff. Thanks for all the help tho guys, I will just have to try something else.