Gyrojets using unused fuel as warhead/extra kick?

[RogerBW]

Yeah, pure rocket rounds don't seem to work at a handgun size, which I think is why we haven't seen anyone have another go at making it happen. FFARs and missiles and things are generally launched off fast-moving vehicles, or have an initial launch charge to get them up to speed, and the better ones are guided.

[Varyon]

Originally Posted by Agemegos

The fuel in a gyrojet projectile is all consumed within 0.10–0.12 second — within about thirty feet of the muzzle. At military ranges there is no propellant left to explode.

GURPS gyroc weapons appear to basically burn their fuel for the bulk of their flight, seeing as they lack a 1/2D range.

As for the question at hand, if you need some sort of method for gyrocs to turn their propellant into a proper explosive payload or (as in the case of the baton rounds) be able to do a sudden extreme acceleration just before impact, it's going to use up less mass and be less complicated to just make each bullet have an adjustable rate of propellant burn, put a rangefinder on the firing platform, and have it tell the bullet the burn rate that will result in it using up all fuel in the time it takes to reach the target. Basically, higher thrust for the entire flight against closer targets, lower thrust against more distant ones, rather than some complicated ramp-up midflight. I suspect even then it's not really worth it - maybe you can manage a few more points of damage against really close targets, but your bullets are going to cost a lot more, and it's possible the added mass of the control mechanisms (so that burn rate can be adjusted) will result in less damage against distant targets, compared to a "dumb" gyroc.

[malloyd]

Originally Posted by RogerBW

Yeah, pure rocket rounds don't seem to work at a handgun size, which I think is why we haven't seen anyone have another go at making it happen. FFARs and missiles and things are generally launched off fast-moving vehicles, or have an initial launch charge to get them up to speed, and the better ones are guided.

I think that is basically it. Gyrojets are small missile launchers. You don't see much of them because it's hard to fit much capability into a really small missile (potentially a fixable problem with ultratech), and because small arms are designed to be issued in large numbers, and micro-missiles are *expensive*. Indeed as modest as its missile-like capabilities were, this was one of the commercial problems with gyrojet. The rounds cost so much that gun enthusiasts couldn't afford to take it the range very often, and if you can't get a military to adopt, recreational shooters are your market.

I'd note that you don't see very many full sized missiles that do terminal accelerations or try to explode excess fuel. If it's not worth doing in an SAM, it's hard to see how it's going to be a useful feature in a gyrojet.

[Varyon]

Originally Posted by malloyd

I'd note that you don't see very many full sized missiles that do terminal accelerations or try to explode excess fuel. If it's not worth doing in an SAM, it's hard to see how it's going to be a useful feature in a gyrojet.

Some energy sources, like supercapacitors, metallic hydrogen, or anything with antimatter, may be able to make a decent explosion on impact without needing to waste any mass on fuses, primers, etc. I know this is how I intend missiles to largely function in Harpyias, where they get their energy from extremely high-energy capacitors and turn that into velocity with the help of superscience mumbo-jumbo. Of course, using the capacitor as a warhead is only really feasible there because a) the capacitors in that setting are themselves superscience and have an energy density in excess of most modern high explosives (50 MJ/ton, or roughly REF 10) and b) the superscience drives have a rather low velocity cap, making kinetic kills more difficult. Absent that sort of contrived setting, turning your fuel - whatever it is - into kinetic energy is almost certainly going to be better than making it explode. Indeed, I think when I designed a missile using Spaceships (making it as a small missile), and loading its fuel tanks with HEDM (for which I used the REF of metallic hydrogen to work out the "boom"), it pretty consistently dealt more damage the less fuel it had remaining, because burning up the HEDM to generate more velocity resulted in more damage than the explosion.

[Ulzgoroth]

Originally Posted by Varyon

Indeed, I think when I designed a missile using Spaceships (making it as a small missile), and loading its fuel tanks with HEDM (for which I used the REF of metallic hydrogen to work out the "boom"), it pretty consistently dealt more damage the less fuel it had remaining, because burning up the HEDM to generate more velocity resulted in more damage than the explosion.

Did you adjust the Spaceships ramming rules to account for the actual remaining mass of the ship? Because I'm pretty sure if you don't you're effectively counting the burned HEDM twice - once as reaction mass and once as (inert) impact mass.

[Varyon]

Originally Posted by Ulzgoroth

Did you adjust the Spaceships ramming rules to account for the actual remaining mass of the ship? Because I'm pretty sure if you don't you're effectively counting the burned HEDM twice - once as reaction mass and once as (inert) impact mass.

I believe so, yes, but I'm working off of memory here and it was quite some time ago. I do know I specifically used the REF of metallic hydrogen (as supplied in either Basic Set or Ultra Tech) rather than the Spaceships rules for exploding volatile systems, as I believe the latter ended up making the explosion more powerful (of course, it also didn't scale - it doesn't matter if you have one fuel tank or ten, or if you use metallic hydrogen or a 50/50 mix of matter and antimatter, it's the same size of explosion when it goes off, with damage scaling only with vessel size).

[Joseph Paul]

Originally Posted by malloyd

I think that is basically it. <SNIP!>
I'd note that you don't see very many full sized missiles that do terminal accelerations or try to explode excess fuel. If it's not worth doing in an SAM, it's hard to see how it's going to be a useful feature in a gyrojet.

So what does happen to the remaining fuel in a ground launched Sidewinder when it's proximity fused fragmentation warhead goes off? How about anything with a liquid fuel like a Bomarc?

[Fred Brackin]

Originally Posted by Joseph Paul

So what does happen to the remaining fuel in a ground launched Sidewinder when it's proximity fused fragmentation warhead goes off? How about anything with a liquid fuel like a Bomarc?

Unburned solid fuel could form burning fragments but they might also be extinguished by the blast. They wouldn't fly as far as the actual frag from the warhead.

For Bomarcs probably no one now alive knows what happened in testing even if they knew back when i was a very small child. It all would have been at high altitude and would have been rendered moot by the W40 nuclear warhead anyway.

As I mentioned earlier with the airbreathing liquid fueled Exocet the unburned jet fuel gives an improved incendiary effect that might have ended up causing more damage in the Falklands than the direct blast.

[Rupert]

Originally Posted by Joseph Paul

So what does happen to the remaining fuel in a ground launched Sidewinder when it's proximity fused fragmentation warhead goes off? How about anything with a liquid fuel like a Bomarc?

I'm not sure about the sidewinder, but many AAMs burn their fuel very quickly and 'coast' to their targets.

[Joseph Paul]

Originally Posted by Rupert

I'm not sure about the sidewinder, but many AAMs burn their fuel very quickly and 'coast' to their targets.

Looking at this forum https://www.key.aero/forum/modern-mi...ange-questions

And it is making my eyes bleed. The questions need to be VERY specific to get any meaningful answers.