When does a rocket selfdestruct?

[TheCardinal]

How often doesn't one of yours craft behave the way you expected? (If it is as often as with mine, it happens more than you like.)

I started wondering under what circumstances a craft should selfdestruct. "When the craft deviates too much from it's desired flightpath" is an accurate but unusable rule i.m.o. as craft usually deviate a lot from their desired flightpath in KSP. At the moment, the best i could come up with is: If the vertical speed is negative and the periapsis is below 70000m and the selfdestruct is armed and the altitude is below 30000m then autodestruct. Additionally, if a craft is manned, the selfdestruct is not armed. An abortprocedure should be activated instead of a selfdestructsequence. The selfdestruct is armed when the craft has risen 5m above the launchpad.

My question to you is: What rule(s) should be added and what should be considered as well.

[K^2]

I was under the impression that other than military missiles, rockets are always destroyed with a command from flight control. If something goes terribly wrong right away off the pad, then situation could only improve if you hesitate to destroy it. And if rocket goes off course at high altitude, there is no harm in waiting to see if some systems kick in and manage to correct it. Anything is better than completely losing the payload and the rocket at that point. I don't know if there is such a thing as, "Yup, we just want it to automatically blow up at this point," even with unmanned rockets. It's all situational.

ICBMs, on the other hand, are not designed to be easily aborted. In fact Soviets used to not have a system to destroy them from ground at all. United States, but all accounts, did, but that still required quite a bit of back and forward. Which is why these kinds of rockets must come with self-destruct mechanisms. Both to avoid collateral and, in some cases, to avoid giving your enemy pieces they can use to reverse engineer your tech.

[Nibb31]

In KSP, why would you bother ?

In US launches, flight range safety is ensured by the USAF, even for civilian launches. The Flight Termination Officer is independant from the launch provider or the customer and is in charge of terminating the flight, even for manned missions.

The decision to terminate the flight is usually made as soon as the rocket deviates from its planned course with no hope of recovery.

[wumpus]

4 hours ago, K^2 said:

ICBMs, on the other hand, are not designed to be easily aborted. In fact Soviets used to not have a system to destroy them from ground at all. United States, but all accounts, did, but that still required quite a bit of back and forward. Which is why these kinds of rockets must come with self-destruct mechanisms. Both to avoid collateral and, in some cases, to avoid giving your enemy pieces they can use to reverse engineer your tech.

While I know nothing of ICBMs, US Navy (anti-air/ship) missiles are programmed to explode if they deviate from course.  This means that any "dud" missile has to be carefully inspected and defused, as the self-destruct mechanism is armed the moment it leaves the launching rail (presumably given to any seaman who has annoyed a chief lately).

Of course, simply detonating the warhead on a small conventional warhead is different from doing the same on an ICBM.  I suppose you could have an "alternative detonation mechanism" which added sufficient pauses between the starter explosives so nothing goes critical, but you would likely still have more secrets than you want to fall into enemy hands and destroying the value of the plutonium would be difficult (I expect you could attach the "wrong" isotope on the back of the plutonium, and set it up so that the "alternate" detonation mixed the isotopes to the point that separating them would be nearly as hard as building a weapon from scratch.  In all likelyhood, ICBM designers were pressured to keep mass low enough that such tricks weren't possible.  The US has at least one nuke missing (in an extremely locked-out swamp in the carolinas) but I still don't think there ever was enough pressure to add that mass.

[Kryten]

A number of groups in the US have been  working on GPS-based automated flight termination for orbital launchers to reduce launch crew requirements, Orbital have already flown test versions.

[magnemoe]

1 hour ago, wumpus said:

While I know nothing of ICBMs, US Navy (anti-air/ship) missiles are programmed to explode if they deviate from course.  This means that any "dud" missile has to be carefully inspected and defused, as the self-destruct mechanism is armed the moment it leaves the launching rail (presumably given to any seaman who has annoyed a chief lately).

Of course, simply detonating the warhead on a small conventional warhead is different from doing the same on an ICBM.  I suppose you could have an "alternative detonation mechanism" which added sufficient pauses between the starter explosives so nothing goes critical, but you would likely still have more secrets than you want to fall into enemy hands and destroying the value of the plutonium would be difficult (I expect you could attach the "wrong" isotope on the back of the plutonium, and set it up so that the "alternate" detonation mixed the isotopes to the point that separating them would be nearly as hard as building a weapon from scratch.  In all likelyhood, ICBM designers were pressured to keep mass low enough that such tricks weren't possible.  The US has at least one nuke missing (in an extremely locked-out swamp in the carolinas) but I still don't think there ever was enough pressure to add that mass.

So if missile derivative significant from course if on an fixed trajectory, I also guess this happen if it misses an lock on and is unable to reacquire it it will blow up. 
For missiles this is simple just set off the warhead. And no missile is not armed at launch, even dumb rpg warheads has to travel 50 or some meter to arm. This is longer for heavier weapons, 
An self destruct system is to increase safety not make it less safe, main problem would probably be that the missile engine might fire, it was set to fire but did not, however its still set to fire.
 

[StrandedonEarth]

In KSP, the self destruct is triggered when shortly after Jeb starts wondering "What does this big red button do?"

Edited August 17, 2016 by StrandedonEarth
Let me rephrase that...

[Wjolcz]

When a flatearther denies it, it goes poof. Also a panda dies in the process.

[Firemetal]

1 hour ago, StrandedonEarth said:

In KSP, the self destruct is triggered when Jeb starts wondering "What does this big red button do?"

Hey that's exactly what I think!

[K^2]

13 hours ago, wumpus said:

Of course, simply detonating the warhead on a small conventional warhead is different from doing the same on an ICBM.  I suppose you could have an "alternative detonation mechanism" which added sufficient pauses between the starter explosives so nothing goes critical

That's pretty much how it works. Detonation mechanism is simply triggered with wrong timing, causing loss of symmetry, and instead of implosion, you end up with warhead blown into itsy bits. This usually results in total destruction of flight and detonation systems^*, which are the most carefully guarded parts. Engine fragments might be recoverable, but not much you can do about that without adding a lot of extra weight and potential for something to go wrong. And yeah, most of the plutonium just falls into someone's back yard.

^* In Soviet ICBMs, guidance and detonation systems were pretty much inseparable. This was meant as a safeguard against someone stealing a warhead and detonating it. So without taking the whole thing apart and rebuilding detonation system, the only way for it to go off was for the guidance program to run its course. And given that the whole thing was almost entirely mechanical, using integrating gyros to verify trajectory, these things were very difficult to mess with.

US missiles relied a lot more on electronics, so I suspect the warhead just needed to receive an activation code from the guidance or receiver unit.

[jwenting]

12 hours ago, magnemoe said:

So if missile derivative significant from course if on an fixed trajectory, I also guess this happen if it misses an lock on and is unable to reacquire it it will blow up. 
For missiles this is simple just set off the warhead. And no missile is not armed at launch, even dumb rpg warheads has to travel 50 or some meter to arm. This is longer for heavier weapons, 
An self destruct system is to increase safety not make it less safe, main problem would probably be that the missile engine might fire, it was set to fire but did not, however its still set to fire.
 

Which is why self destruct mechanisms aren't triggered by the launch signal + a timer, but by other things like accellerometers, pressure sensors (altitude), and things like that, often in combination with a timer.

So for example a self destruct system might only trigger if the weapon has reached a certain speed + been over and then dropped under a specific altitude, all no sooner than a set number of seconds after launch and no later than another set number of seconds (to avoid it triggering during the terminal flight profile over the intended target).

[DDE]

On ‎17‎.‎08‎.‎2016 at 7:07 PM, Kryten said:

A number of groups in the US have been  working on GPS-based automated flight termination for orbital launchers to reduce launch crew requirements, Orbital have already flown test versions.

Ze Russians claim to have had an onboard fault detection and pad destruction avoidance routine integrated into the control system since the R-7. At least that's what they've been saying after the Antares explosion when someone raised the possibility of a range safety self destruct being involved.

Edited August 18, 2016 by DDE

[magnemoe]

14 hours ago, jwenting said:

Which is why self destruct mechanisms aren't triggered by the launch signal + a timer, but by other things like accellerometers, pressure sensors (altitude), and things like that, often in combination with a timer.

So for example a self destruct system might only trigger if the weapon has reached a certain speed + been over and then dropped under a specific altitude, all no sooner than a set number of seconds after launch and no later than another set number of seconds (to avoid it triggering during the terminal flight profile over the intended target).

Yes I assume it require the weapon to be armed first, and then something has to go wrong, either out of control or loosing target and is unable to reacquire. 

[TheCardinal]

I've always believed that i.r.l. the onboard computer had the posibility to initiate the selfdestruct (on recent craft). On hind sight, it seems more and more inprobable, i can remember a chinese rocket which destroyed a village when the launch failed due to a undetached line. But in most cases the launch site is a remote location in an unpopulated area, thereby removing the need for an automatic selfdestruct.

Is it silly to create such a mechanism for KSP launches?

 

[magnemoe]

6 minutes ago, TheCardinal said:

I've always believed that i.r.l. the onboard computer had the posibility to initiate the selfdestruct (on recent craft). On hind sight, it seems more and more inprobable, i can remember a chinese rocket which destroyed a village when the launch failed due to a undetached line. But in most cases the launch site is a remote location in an unpopulated area, thereby removing the need for an automatic selfdestruct.

Is it silly to create such a mechanism for KSP launches?

In KSP its only relevant if you are in danger of hitting the launchpad or other part of KSC.
In both settings you are likely to be to be too low for it to help much, as KSP rockets are designed of parts you might well do more damage by generating lots of fragments who hit the space center as an cluster bomb. 
 

[wumpus]

On 8/18/2016 at 2:41 AM, jwenting said:

Which is why self destruct mechanisms aren't triggered by the launch signal + a timer, but by other things like accellerometers, pressure sensors (altitude), and things like that, often in combination with a timer.

So for example a self destruct system might only trigger if the weapon has reached a certain speed + been over and then dropped under a specific altitude, all no sooner than a set number of seconds after launch and no later than another set number of seconds (to avoid it triggering during the terminal flight profile over the intended target).

Was that when they learned that ground initiated escape systems were sub-optimal?  That sounded like a hairy flight.

Edit: Oddly enough, I was trying to quote the following:

On 8/18/2016 at 4:52 PM, DDE said:

Ze Russians claim to have had an onboard fault detection and pad destruction avoidance routine integrated into the control system since the R-7. At least that's what they've been saying after the Antares explosion when someone raised the possibility of a range safety self destruct being involved.

The "hairy flight" meaning one where the Cosmonauts in question were well aware that their rocket was about to explode and waiting for ground control to get the escape to work.  I think they finally ejected (presumably the entire Soyuz capsule) with about a second to go before the rocket exploded.

Edited August 19, 2016 by wumpus

[Kryten]

5 minutes ago, wumpus said:

Was that when they learned that ground initiated escape systems were sub-optimal?  That sounded like a hairy flight.

There was a live nuclear warhead involved, so 'hairy' is a bit of an understatement.

[jwenting]

1 hour ago, Kryten said:

There was a live nuclear warhead involved, so 'hairy' is a bit of an understatement.

That's why warheads aren't typically armed until near the intended target.

Though that sometimes can go wrong as well. As with a lost US bomber over New England, where a bomb was shaken loose from the crashing airframe, and the flight profile of the accidental drop was such that all but one of the (6 I think, was a while since I read the account) triggers had done their job by the time it burrowed itself into a deep hole in the ground of its own creation.
This accident got so close to an accidental nuclear explosion over US territory that the AEC and USAF went into overdrive to develop new safeguards and operational procedures.

[TheCardinal]

3 hours ago, jwenting said:

That's why warheads aren't typically armed until near the intended target.

Though that sometimes can go wrong as well. As with a lost US bomber over New England, where a bomb was shaken loose from the crashing airframe, and the flight profile of the accidental drop was such that all but one of the (6 I think, was a while since I read the account) triggers had done their job by the time it burrowed itself into a deep hole in the ground of its own creation.
This accident got so close to an accidental nuclear explosion over US territory that the AEC and USAF went into overdrive to develop new safeguards and operational procedures.

There have been many incidents like that, including "The Damascus Accident" (Youtube video).

[jwenting]

5 hours ago, TheCardinal said:

There have been many incidents like that, including "The Damascus Accident" (Youtube video).

Yes, there were several accidental releases (almost all related to aircraft breaking up in mid air, either from structural failure or after collisions). But none got as close to detonation as that one. In fact most fell harmlessly and were either recovered without problems or broke apart and the contaminated soil was carted off.