POLL: Has Anyone ever had to do an abort Using LES?

[Cheif Operations Director]

Has another ever actually had to do an inflight abort to save your crew. I think the only time I had too actually do an abort with LES was when my rocket was too heavy for the launch pad and the center tanks blew up. I also seem to remember having to abort once due to heating causing a pre-mature detachment of a stage. 

 

 

[Geonovast]

Yup.  Playing no reverts right now (unless caused by a bug).  Have had two launches go bad due to bad staging on one and pitching too early on another.  The pitching too early had 6 tourists on board... so glad I had the LES on that.

LES testing is becoming one of my favorite parts of designing a rocket.

[Cheif Operations Director]

1 minute ago, Geonovast said:

Yup.  Playing no reverts right now (unless caused by a bug).  Have had two launches go bad due to bad staging on one and pitching too early on another.  The pitching too early had 6 tourists on board... so glad I had the LES on that.

LES testing is becoming one of my favorite parts of designing a rocket.

Likewise, I wish there was a detonater part so you could just blow up rockets whenever you want to. and my blow up I mean large smoke clouds instatenous explosion etc

[Geonovast]

1 minute ago, Cheif Operations Director said:

Likewise, I wish there was a detonater part so you could just blow up rockets whenever you want to. and my blow up I mean large smoke clouds instatenous explosion etc

Not stock, but that is a mod.  I use it for my upper stages that I can't (or am too lazy to) deorbit.

 

[Cheif Operations Director]

Just now, Geonovast said:

Not stock, but that is a mod.  I use it for my upper stages that I can't (or am too lazy to) deorbit.

 

Nice I will look into it

[Loskene]

Playing without reverts is the only thing that makes me design a LES on every crewed craft so yes, and it is quite satisfying when they work, offsets some of the frustration of not going to space today.

[linuxgurugamer]

I allow myself reverts in three cases:

• A game bug
• Doing a challenge
• When playing a career game, I allow myself one mulligan per evening (when I stream); in other words, one do-over.  When in career, I will do any number of test flights, but when I'm doing it for real, I declare it and then have to stay by whatever happens

[Bran31]

Yes, for sure. I've found my most common abort situations are when I've had booster issues, or warping of the central stages, so that the vehicle skews and is either in danger of, or begins a rapid unplanned disassembly. I've had solid fuel boosters detach while still running (needs more struts) and threaten the crewed compartments, prompting an abort as well.

[Selentic]

I've done a number of LES aborts during flight, a couple on the ground, and one accidental one during orbital insertion when the staging got mixed up.

I tend to only play campaigns with KCT and Kerbalism running, so when something goes wrong during a non-"simulated" launch I need a way to save as much of that expensive payload as possible! I do have to note, looking over my last campaign's designs, however, that once I unlocked the nose-cone docking ports, I retired the LES in favour of seperatrons strapped to the capsule or interstage...

Also, playing with a part failure mod makes having abort modes in your design a must!

[razark]

I've used LES when staging boosters into my core engines, or when the launch failure mod kicks in.

(What's the point of using the failure mod if one is just going to revert?)

 

 

Edit:

I will use reverts if it's due to a game issue, and not a bad design issue.

Edited August 21, 2019 by razark

[Pecan]

House Rule 1: Every crewed launch needs an escape system, although the size of the 'proper' LES means it is not always suitable.  In that case something similar with sepratrons may be used.

[kerbiloid]

If LES and deorbit may have similar delta-V, just use a solid motor beneath the capsule instead of the tower.
Then you don't need to stupidly jettison it every flight. Just you will use it either as a LES, or as a deorbit retrorocket.
Also it will never be out of fuel, as doesn't spend it.

[Geonovast]

Just now, kerbiloid said:

If LES and deorbit may have similar delta-V

The problem isn't dV, it's TWR.  A deorbit system likely isn't to have a very high TWR, but is likely to have a high ISP to make it lightweight.

And abort system is the exact opposite.  You need a TWR much higher than the rocket you're trying to get away from, ISP be damned.  When SpaceX was planning to dual-purpose their abort motors, it wasn't for de-orbiting, it was for landing - another high TWR scenario.

[kerbiloid]

4 minutes ago, Geonovast said:

The problem isn't dV, it's TWR.

3 x engines, each 4 g.
One by one in deorbit mode, all at once as LES.

(Though in game you can just deorbit at 12 g, so save part count.)

Edited August 22, 2019 by kerbiloid

[razark]

16 minutes ago, kerbiloid said:

If LES and deorbit may have similar delta-V, just use a solid motor beneath the capsule instead of the tower.

My LES is often sepratrons stuck on the capsule.  I often use it during reentry for additional slowing power.

[adsii1970]

I love using them. It's a prerequisite whenever I construct a new rocket/lifter design. I even have a mod by @Angel-125 (BARIS) which causes random problems - and there have been more than a dozen times when I've had to evacuate a crew. Yeah, I get really attached to my Kermen.

[Cavscout74]

I play with Kerbal Launch Failure, and generally use hard settings in career (no revert or quickload, kerbals can die), so LES is generally required.  I've also started using the PEBKAC Launch Escape Systems mod.  Even before I started using KLF, I had started using LES just in case, and had to use it twice due to design failures in the same design - radial boosters had more rotation than I expected at staging & they destroyed 2 out of 4 core engines.  After the first one, I adjusted the design & on the next flight, the radial boosters managed to take out the core fuel tank just above the engines.

I also am very fond of the new kerbal parachutes - Kerbal Launch Failure reared its head one day & blew up an engine on a spaceplane full of 6 kerbals one day.  The crew compartment and some wing pieces survived, but not much else.  I had to EVA each kerbal & deploy his or her chute, switch back to the wreck & EVA the next one, while plummeting towards the ocean below.   I managed to parachute all 6 into the ocean & recover them all safely.

[CaelumEtAstra]

No, I hope I never need to. I build and fly my rockets to be reliable as I have a policy of only reverting in the event of glitches or minor goofs. That said, I always add them to my capsule designs--it's better to have it and not need it, than need it and not have it.

[Superfluous J]

Nope. The only time I've ever used the LES was to play with it when it first came out.

[Pds314]

I have done launch aborts with rockets, but usually LES is the inappropriate tool for the job. For one, it weighs 1130 kg fully fueled. And don't think you're saving a lot by draining some of that. Because it weighs 900 kg empty.

 

It does have a good TWR. Maybe its sole redeeming characteristic, but this usually is not only unnecessary but actually a safety hazard. LES on a 2.5m command pod gives you 20 G acceleration. And remember that the only reason you ever need to use it is to stop some part of your rocket that's blowing up from destroying that. You certainly won't be trying to save most non-living payloads with it. And in many situations, accidental trigger of LES or using it as the automatic launch abort is actively endangering your Kerbals. For example, inside a fairing, LES would likely either kill you or trap you in a rocket you can't control. Meanwhile if you are too low and your capsule is overheating, LES would probably ensure it explodes from overheat. If you forgot a decoupler, LES may not detach your pod, but may drag at some lightweigh weakly-attached payload until something breaks. Which could hit your capsule.

So for something that requires such large investment in launch mass, there is really only one situation it can be used it. Structural failure or a very specific type of staging mishap on a rocket with a large pod that isn't bolted to a heavy payload. The question is, can I match this safety improvement in less than 1130 kg of suborbital payload? And usually the answer is yes.

Edited August 23, 2019 by Pds314

[Loskene]

4 hours ago, Cavscout74 said:

I had to EVA each kerbal & deploy his or her chute, switch back to the wreck & EVA the next one, while plummeting towards the ocean below.   I managed to parachute all 6 into the ocean & recover them all safely.

Nice. I've yet to have a plane break up with enough altitude to let me bail out all the Kerbals in time, but then I rarely build SSTO spaceplanes. I've taken to making sure all my test flights are done with only a single pilot on board instead. If anyone else sneaks aboard while I'm making edits, on their gargantuan heads be it.

[Incarnation of Chaos]

Iv'e never used the actual LES; by the time you're flinging multiple ton landers around it's somewhat pointless. But i have done plenty of aborts to orbit; where something goes horribly wrong and i just stage the lander engine, which then burns off the stack below and forces seperation. Then i'll normally have a nice low periapsis that i'll use to aerobreak down with; ofc this is only really possible because i massively overengineer these things to have decent TWR even in the atmosphere but meh.

[ExtremeSquared]

Top node is always either a docking port or parachute. I would definitely use the LES if it attached without needing the node.

[kerbiloid]

12 hours ago, 5thHorseman said:

The only time I've ever used the LES was to play with it when it first came out.

That's wise. We don't need unlucky ones in space, why save them.

[razark]

2 hours ago, ExtremeSquared said:

Top node is always either a docking port or parachute. I would definitely use the LES if it attached without needing the node.

When I use the stock LES, I attach it to the top docking port.  You can set it to decouple in staging, which allows you to use both.

My Abort action is to decouple the capsule from the stack and fire the LES.  In staging, I have it set to decouple the docking port and fire the LES at the point it's no longer needed.