As I understand it, GyroJets used a solid fuel: how was it ignited?

The chamber wasn't sealed (I think), so there was not the pressure spike seen in a 'normal' cartridge. (Was the fuel just very-slow-burning nitrocellulose?)

Any ideas?

Thanks, the_captn

I killed this reply..too many typos...

[ 10-08-2003, 04:47: Message edited by: ricciardelli ]

Fuel was solid rocket fuel. It was ignited by slamming the "cartridge" backwards into the "firing pin". This caused the fuel to ignite.

The gases from the ignited fuel were released out of angled portholes in the bottom of the "cartridge".

It was actually possible to put your hand in front of the "launching ramp" of the GyroJet and stop the projectile. It was also possible to cause one hell of a brush fire if you fired it into dry grass at close range.

The unadvertised intention for the GyroJet was that it was to be the "Spacegun" of the future Astronauts...no oxygen required, no recoil, and terminal velocity was the same as maximum velocity, no matter what the range.

Thank God it never made it!

Gyros used a special slow burning solid state fuel, ignited by a regular small arms primer. It's fuel mixture was proprietery and very closely kept, but a few copies of "Gyrojet Theory and Technology" (or something like that) did escape... I am hot on the heels of tracking one down in California... Reminds me.
I think i'll call him tommorow

The "catch-a-Gyro-in-your-hand" is more myth than anything.
The actual revoloution-per-second, and this is a "I recall hearing", was over 1K rp/s, so aside from burning the hell out of your hand, it was still traveling round-about 500/600 fps at the muzzle.

SAR wrote an article recently where they tried to catch one in a mason jar. Needless to say, it blew through the mason jar, and went on it's merry way.

They aren't reloadable, but they would be very easy to make- 100X moreso today in the CNC era than was possible in Mainhardts day when the rockets were actually turned by hand on lathes.
Furthermore, advances in fuels would make the rockets absolutley reliable.

There were 2 different types of 13MM rockets commonly seen (not including the 13MM Magnum rounds that were produced by MBA as prototypes)
The first is the "wadcutter" round- With a SWC shaped meplate. The next would be closer to a traditionial RN profile.

The ATF has imposed new regulations on rocket fuel commonly used by hobbyists. I am applying for my permit this year, and i'll let you know how it goes.

Ricciardelli is dead on the money about the Gyros unspoken intent being for Astronauts. MBAssociates was VERY closley tied with Uncle Sams "quieter" agencies all throughout it's existance. There are even a few "black bag" conspiracy theories that exist about the company.

The Gyro technology was young- and if given a chance today with modern materials and manufacturing techniques, would be a far more viable product.
It was a shame it was left to die on the vine, but in years to come, that may change.

[ 10-08-2003, 05:02: Message edited by: McUZI ]

Although there's still no air needed to fire a cartridge loaded with nitrocellulose powder. The primer flash would make more than enough hot gas to do the job even if the inside of the case were highly evacuated. I think it'd be preferable to seal the case well enough to maintain fairly normal atmospheric pressure, though, as powder contains some residual solvent and mosture and removing that will change its burning characteristics. The recoil is rather problematic under weightless conditions. High speed particles of unburned powder from either a gun's muzzle blast or a rocket's exhaust could be hazardous to great distances in the vacuum of space.

Back to the 'black bag' plans. Somewhere I still have articles with photos of smaller 'needle' type projectiles and launchers for concealed carry as well as versions for use underwater by 'special' divers. I wonder who they would have worked for?

McUZI:
Catching a Gyro is not a myth...I did it...but not bare-handed, I was wearing a leather welder's glove.

The original projectiles were 13mm, but in 1968 (the year of the famous GCA) they were changed to 12mm, simply because the 1968 GCA classified ANY projectile of over .50 caliber a "destructive device".

NotRicochet:
Have you ever fired the GyroJet? I have...

There is NO recoil to the GyroJet.

And the major problem with the projectile was moisture. MBA supposedly wanted to market it for Viet Nam (another testing ground for another useless weapon, causing lost American lives). There were two problems in Nam with it. Failure to fire in humid conditions, and gross inaccuracy (I mean REALLY BAD!!). With all jet ports clear and clean, the GyroJet was in reality, under ideal earth conditions, accurate to around 35-40 yards. If one of the ports were dirty or clogged, it would spin off into Never-Never-Land the moment it left the launcher...

The Vietnam thing wasn't really a "testing ground". It's intent was to be a cheap weapon that could be given to VC farmers to defeat NVA light armor.
Matter of fact, one of the first Gold Presentation models was presented to the president of South Vietnam.

There are two decently documented instances of Gyro's in combat by US Soldiers in 'Nam- Hardly what one would call a "testing ground".
One was a personally owned MKII Pistol that was returned in the personal effects of a KIA American Soldier- the other was this one from a Special Forces guy...

quote:

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I was issued one, a 13mm Bensen Gyrojet, in Vietnam, SOA (CCC), in February or March 1969, right out of thesupply room, along with a couple dozen rockets. I used it as my "belly gun", on a lanyard around my neck andtucked into a claymore bag across my chest. It was very light, even fully loaded, so the weight wasn't a problem. Alittle big and bulky, but no worse than a .45, and shorter than the .22 silenced Hi-standards that were also available.Never cleaned it the entire 10 months or so I had it. Nothing to rust, all aluminum and alloy, beautiful woodengrips. Light, simple, and despite what you may read elsewhere, absolutely DEAD-ON accurate at 10 or 20 yards.Demonstrating its sound and performance to my Recon Team Montagnards, I put one rocket dead-center into a logat 20 meters, then a second rocket right in behind the first, in the same hole. Seemed to be as accurate as anyother pistol I've ever fired (and I shot a lot) out to 30 meters or so. And anyone shooting over 30 meters with ahandgun is a damned fool anyway.You have to give the rocket a few yards to get up to speed though; as written elsewhere, muzzle velocity wasabout zilch, but was quite respectable a few yards out. Not the gun you'd stick into someone's belly though .. unlessyou wanted to share a good laugh.To test penetration of the copper-colored rockets, I fired one into a row of one 50-cal ammo can full of dirt fromabout 10 yards. "Psssssssst!" Hit the front ammo can absolutely dead center (told you it was accurate).There was a big spray of dirt out of the first can because the rocket was still burning and the exhaust blew outsome of the dirt; kind of startling until I realized what had happened.I went to retrieve the rocket (to check it for denting, damage, mushrooming, whatever) and couldn't find it: it hadpenetrated the ammo can, went into the clay bank behind the cans so far I couldn't find it (after digging in severalfeet with my K-bar).But the rounds could be a bit peculiar. Down at the river near Kontum on sandbag detail, I fired a rocket into abanyan sort of tree down by a river. Tree had these curved roots that sloped up into the main trunk. The rocketripped a strip or gouge up the curved root, looped up in the air, and fell back down into the sandy shore literally atmy feet! I looked at the rocket sitting there in a little crater of sand and noticed the slightest puff of sand. Turns out itwas still spinning along its axis at a terrific rate! (The rocket jets were canted to give each round a spin since therewere no lands and grooves in the simple aluminum tube barrel.) Took maybe a minute to finally stop. No tellingwhat the RPM was, but VERY high! And the rocket was hot as hell, burned my fingers when I picked it up, eitherfrom friction against the sand (although doubtful, it hardly moved the sand at all) or from the rocket motor burn it-self.As a Recon man I liked the weapon just fine: light, quiet, low-maintenance, and a hell of a punch. (I'd read some-where in its literature that it had 1800 foot-pounds of impact .. or some such figure, can't remember now .. but it wassupposedly "half-again the impact of a .45 ACP."I can't remember the muzzle velocity from the weapon's manual. But we're talking a 13mm rocket slightly over 13/8" long (just got one out and measured it). No scale to weigh it, but it's easily twice as heavy as a .45 ACP slug.So that's a lot of weight whooshing out there! And a pointed tip, not blunt like a .45.I lay beside a well-traveled trail "deep within enemy territory" for most of a day waiting to shoot some poor suffer-ing NVA bastard in the hip with it, but no one ever came. Never did shoot anyone with it.It was not silent, not like the true silenced .22 Hi-standards we often carried. But it was quiet, made a sort of"Psssssst!" sound like air escaping from a truck tire, maybe a half-second long. People would hear it, look aroundcuriously like "What the hell was that?", and go about their business, because it didn't SOUND like a weapon, itdidn't SOUND dangerous! (I fired it in camp several times, demonstrating it, never got any attention at all.)It was fully weatherproof, gun and rockets. I lay besides an LZ one day, hiding, waiting for the rain to stop andchoppers to come. When I got back to CCC, I checked the pistol: the barrel and cocking/firing mechanism had filledcompletely with sand and clay that had washed down the bank to where I was lying on my chest.I figured what the hell, let's shoot it off to see if it'll push the mud out. (Not like a regular pistol, where a pluggedbarrel would probably explode.) I fired it, wondering if the rocket would clear the barrel. I was surprised to see thefiring mechanism actually work despite all the sand and clay! But the rocket didn't clear the barrel: it went "Pssssst!"just like always, but jammed in the barrel.I took the pistol to the latrine, washed it out in a stream of water to clear out the sand. I recocked it manually (the"hammer" was in front of the rocket), poked a stick down the barrel and knocked the jammed rocket loose (it hadonly moved a fraction of an inch, hadn't even recocked the "hammer". Then I removed the expended rocket, let anew rocket move up into the firing position, closed it back up again, and fired off the next rocket (that had beensoaking wet for a week or more). No problem, fired just fine.The biggest problem was the feed design. The rockets all pushed down into the hand grip of the pistol against aspring and follower. Then, while holding that last rocket down, you slid forward this cover on the top of the "re-ceiver" that held them all in place. Fine and dandy if you were going to just shoot them. But shame on you if youhad a misfire (although I never did) or a jam (which I did, once, re above). You'd have to slide back that slide,meanwhile holding all the rockets down with your thumb, and then they'd all want to come springing out! The designreally REALLY sucked. It should've had a magazine like a regular automatic, instead of everything being integral.Impossible to clear in combat, and a real PITA to reload too.Never the less, I liked the pistol just fine, and kind of got off on the "Buck Rogers" aspect of the thing. And it WASdangerous and effective as hell for a handgun! I carried it everywhere I went, all the time, felt naked when I went onR&R to Hawaii and had to leave it behind. And on the CCK R&R to Taiwan too.When in full kit, it was tucked into my Claymore bag right in front of my chest. Otherwise, tucked into my waist-band (even if the stupid cocking lever did dig into me a little) or down in a jungle fatigue leg pocket.I really regretted having to turn that weapon back in when I left Vietnam. But I DID smuggle back a couple of the13mm rockets, have them right in the other room in my souvenir case. Bet they'll fire just fine too .. even though it'sbeen almost 32 years.That's my recollections. I'm looking at a live 13mm rocket right now (and there's a 13mm "canopy buster" penflare they made too, although not for the Gyrojet pistol). Wish I had the pistol, I'll tell you that

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I own a 13MM Cased Presentation model, and must say, it is bar-none without question far and away the coolest gun I own

[ 10-08-2003, 09:36: Message edited by: McUZI ]

Hey steve, I haven't fired a Gyrojet. Would certainly like to. I knew it was recoilless. I was talking about the old "problem" of firing a gun in space, with a conventional cartridge.

The 2002 Sept/Oct issue of the IAA Jrnl has an article on 'Secret experimental' devices, including an adaptor allowing a (.308) gyrojet to be fired from a standard rifle. It also shows several 'mini rockets' down to 1.5 mm diameter---some made by MBA, the makers of the 'normal' GyroJets.

McUzi: I'd be interested in your pursuit of the GyroJet Secrets book(let).

How strong is (was) the spring on the 'hammer'? If the GyroJet could be caught by hand (at the muzzle), the spring could not resist the projectile with too much inertia/force.

the_captn