How to recover solid rocket boosters in full 1.1 campaign?

[bewing]

Kickbacks are worth 2400 kerbucks each, and I recover 97.5% of their value (plus the parachutes, plus the aero fins, plus the landing legs, plus the decoupler). It depends on where they land and what you have your settings set to. But if I weren't recovering them, then I could perhaps use a more efficient launch profile. So as a rough estimate, I save about 5000 kerbucks on a typical launch by recovering my first stage SRBs. According to my playing style, the accountants in my Space Program make me do it.

Edited April 25, 2016 by bewing

[Harry Rhodan]

7 minutes ago, bewing said:

Kickbacks are worth 2400 kerbucks each

And 1260 Kerbucks of those 2400 are solid fuel that you can't recover because you already dispersed it in the atmosphere.

[jedensuscg]

3 hours ago, Alshain said:

Well it doesn't fit my balance, so either rebalance or leave it like it is with no recovery.

They should add a recovery mod in by default, but allow you to change the percentage of recovered value when you create your career, like you can do with all the other settings such as starting funds, contract reward multipliers etc.  Maybe have it 100% for easy, 50% for hard and have a slider to adjust manually. Everyone is happy. 

[Loren Pechtel]

8 hours ago, Alshain said:

Depends on how you look at it.  Rewarding good design by removing all the challenge from the game, feels more like a punishment.

They can't leave the debris when it is in the atmosphere because they can't calculate physics for it.  They don't know that it will touch down at all, unless it's periapsis is below 0, but what if it isn't?  What if it has a 10km Pe?  It clearly should crash or touch down due to aerodynamics, but since you aren't calculating physics, you would never know that.

So it's a CPU loading problem?  I've got extra cores, calculate the physics on that.  If it's far away from my ship it won't interact and there's no multi-threading issues.  It wouldn't even matter if the engine couldn't perform it in realtime--once something goes outside physics range but with a Pe below the top of the atmosphere it gets pushed off into a routine that calculates it on another core as it has the time to do so.  It disappears from the display and can't be interacted with but if it makes it to the surface it gets recovered and you get a message in the queue.

[wumpus]

6 hours ago, bewing said:

Kickbacks are worth 2400 kerbucks each, and I recover 97.5% of their value (plus the parachutes, plus the aero fins, plus the landing legs, plus the decoupler). It depends on where they land and what you have your settings set to. But if I weren't recovering them, then I could perhaps use a more efficient launch profile. So as a rough estimate, I save about 5000 kerbucks on a typical launch by recovering my first stage SRBs. According to my playing style, the accountants in my Space Program make me do it.

Is that using a mod (probably stage recovery)?  The way I've used kickers, I am at ~10km once I drop my kickers.  To somehow get the kickers back down before the magic ~25km mark, they would have to instantly reverse and head downwards faster than my rocket is going upwards.  So far, I've only found a few ways to do this:

Have a magic "clean up line" further than ~25km.  If 1.1 has one further out than 25km, this becomes a possibility.

Use a mod: simple.  If you want to recover anything in stage 1, using a mod will allow you to do this without fighting KSP limitations every step of the way.  Stage recovery is ideal for simple things like SRBs, Flight manager works great if you want something more like Space-x style recovery.

Take the whole thing to orbit: Typically reserved for liquid fuel stages.  Don't decouple the SRBs, but let the whole stage 1 make it to orbit.  The whole operation is similar to a space-x flight: you keep some reserve in the first stage.  Fire both stages to an AP in space, then circularize separately.  Bring stage 1 down to space and let stage 2 continue the mission.  Note that I suspect that SRBs will blow up on the way down, and the only way I've done this is by jettisoning SRBs and recovering mainsails and larger stage 1s.  Warning: this makes "going into orbit" multiple times more tedious than normal KSP and can burn you out.  Consider landing and returning from Eve before digging this hole.

Use a complicated recovery mechanism: Since the kicker is empty, you can presumably accelerate it faster than a loaded rocket.  Recommended only if you need to do many launches with the same launcher.

[bewing]

44 minutes ago, wumpus said:

Take the whole thing to orbit: Typically reserved for liquid fuel stages.  Don't decouple the SRBs, but let the whole stage 1 make it to orbit.  The whole operation is similar to a space-x flight: you keep some reserve in the first stage.  Fire both stages to an AP in space, then circularize separately.  Bring stage 1 down to space and let stage 2 continue the mission.  Note that I suspect that SRBs will blow up on the way down, and the only way I've done this is by jettisoning SRBs and recovering mainsails and larger stage 1s.  Warning: this makes "going into orbit" multiple times more tedious than normal KSP and can burn you out.  Consider landing and returning from Eve before digging this hole.

This works easy for SRBs, too. The SRBs boost everything to an Ap of 150km to 250km, straight up. You have a few minutes to begin the process of circularizing the upper stage (you need a while with nukes or terriers).

When the SRBs fall back down to maybe 55km altitude, you switch focus back to them. If you are clever about your aerodynamics, the SRBs survive reentry just fine, and slow to 200 m/s by 3km altitude. The chutes autodeploy and the SRBs land (velocity = maybe 11 m/s) a little west of KSC. And you need something clever to absorb that 11 m/s. If LT1 landing legs are working, they can handle 12.

[Loren Pechtel]

11 minutes ago, bewing said:

This works easy for SRBs, too. The SRBs boost everything to an Ap of 150km to 250km, straight up. You have a few minutes to begin the process of circularizing the upper stage (you need a while with nukes or terriers).

When the SRBs fall back down to maybe 55km altitude, you switch focus back to them. If you are clever about your aerodynamics, the SRBs survive reentry just fine, and slow to 200 m/s by 3km altitude. The chutes autodeploy and the SRBs land (velocity = maybe 11 m/s) a little west of KSC. And you need something clever to absorb that 11 m/s. If LT1 landing legs are working, they can handle 12.

You can also use multiple chutes or get one of the mods that has bigger chutes.  The Lithobraking mod has some very big chutes in it.  I use Stage Recovery so I don't have to worry about switching to the falling boosters but otherwise it's the same thing.  I set deployment for 1000m and put the chute on the stage with the decoupler.

[wumpus]

4 hours ago, bewing said:

This works easy for SRBs, too. The SRBs boost everything to an Ap of 150km to 250km, straight up. You have a few minutes to begin the process of circularizing the upper stage (you need a while with nukes or terriers).

So you drop them somewhat before burnout (but high enough that they won't destroy themselves with the extreme velocity they generate in the next few miliseconds)?  Note that as far as I know, you have to get out of the atmosphere with your primary rocket before you can switch focus (shouldn't be a problem if it is 150km).  Have to try that sometimes.

Do you ever find that they disappeared by hitting 25km+rocket elevation before hitting space?  Is this one of those things were you have to go straight up because otherwise you will hit the 25km limit sideways?

[bewing]

My SRBs tend to burn out at over 30km, so that's never been an issue for me. I wait for them to burn out completely, then do a gentle decoupling, and fire the next stage when they have separated a little (so I don't blow up the parachutes with the exhaust from my next stage). And no, by launching straight up, they come straight back down, and end up at KSC for a full refund. Also, there is no noodling when you launch straight up, for a second bonus. Third is that I don't tend to do much at all in LKO -- I'm almost always launching vertically direct to Mun or Minmus anyway, for refueling.