Nbk's gyrojet specific

August 7th, 2002, 08:30 AM
nbk2000
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I also have an idea for a 20mm+ man portable direct fire cannon that uses gyrojet type rockets with a rifled barrel and retaining pins similiar to the MLRS system. Rapid fire, recoilless, lightweight (under 25 pounds is light for a "heavy" infantry weapon), explosive effect, able to engage infantry in the open, behind cover, light armored vehicles, helicopters, and bunkers, all within line of sight out to more than a kilometer. Minimal firing signature, quick reloading from preloaded revolver-type drums, alloy and plastic construction (no complicated machining), etc.

Only thing stopping me is a million for R&D. Damn it! Where's the letter M when you need it?!

[ August 07, 2002, 11:52 AM: Message edited by: nbk2000 ]
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May 8th, 2003, 03:29 AM
nbk2000
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I saw a patent for a hypervelocity rocket design that seems so fucking simple, you wonder why no one ever thought of it before. 5,000-12,000FPS using common smokeless powder, no moving parts, and made from common steels using simple machining processes.

(I've described this before, so I feel rather tiresome of repeating myself, but the idea is stuck in my brain so bear with me.)

Skip the bullshit of existing firearm designs and use "Leap Ahead" technology. The gyrojet was decades ahead of its time, but modern technology makes it even more lethal, and practical today then ever before.

Simplify the HVR (HyperVelocity Rocket) design to something you could turn out with a drill press and steel bar stock, create a wax model of a simple (multi-shot) launcher for the HVR, and sell a kit that includes plans/wax model/and some bar stock.

There's NO restrictions on selling either plans, nor inert steel stock, or even a wax model of a "hypothetical" design for a "flare launcher" no one has ever seen before (or remembers).

Great thing about laws are that they can't ban things that no one yet knows exists. It's only AFTER something bad happens with it that someone creates a law banning it.

If someone should happen to follow the plans, and make a casting from the wax model, then they'd have a large caliber/hand-held/recoilless HVR "flare" launcher that'd throw (after burnout) 220 grain (1/2oz) shells with a KE of 31,200 foot-pounds (assuming 8,000FPS).

I mean, Christ, a .50BMG has less than 10,000 foot-pounds, so how many .50s worth of impact would your completely legal and unregulated "flare" launcher have, when directed against cars/body armor/concrete walls/LAV's? All in something light enough, and small enough, to carry in your pocket.

Eventually, someone would bring it to Feinsteins attention, though hopefully not until tens of thousands of the "flare" launcher castings have been sold, as well as the plans and CAD files distributed over the 'net, and piggy torsos are getting exploded (literally) by nearly silent HVR's fired at them by 13 year old ghetto dwelling 'hoodies, the rockets zipping through cop body armor like a hypersonic knife through hot pig lard.

By the time they get around to banning it, you've already established a reputation for yourself as an innovator (or menace to society), created a new industry (legal or underground), given the politicians a case of the shits, and made the pigs realize their vests are useless as protection...and so are their cars...and reinforced concrete walls...and buildings...

Ahh...a sweet dream.
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May 8th, 2003, 06:52 AM
A-BOMB
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NBK I like how you think! It gives me somelike of feeling of some sort like one where your laughing you head off in a movie theater as you see the burning pig stagger out of his burning car onfire And on the subjuect of gyrojets I just saw something at the hardware store that would make a outer casing for a gryojet round it a zinc or brass end fixture for some thing or another I'll pick some up next time I'm there, If these casing are strong anothe to hold the gasses from the cartridge they would make the prefect gyrojet round. The only part that would be a problem is the base you wouuld have to make a jig to hold the base at the right angle while you drilled the vent hole but that too would be semi-easy.
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May 8th, 2003, 06:17 PM
nbk2000
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Brass or zinc would be too soft to be useable as a gyrojet shell. Internal pressures can be over 30,000PSI, which is why strong steels are needed.

Also, the problem with the old gyro's, was the canted ports. Unless they're EXACTLY symetrical, the variance of one port causes an oscillation in the rocket, which is the reason the originals weren't very (or even semi) accurate.

The MLRS method of studs 'n rails would be more suitable. No ports to drill, no loss in velocity from the diversion of propellant gases to induce rotation, and simplified launcher design.

Also, one of the reason for bothering with spin stabilization in the first place, was because the original g-rockets didn't burn all their propellant till they were well downrange. This allowed for wind cocking, which was magnified by the continued acceleration.

The HVR, on the other hand, burns it's entire propellant load in under 10 milliseconds. And this was with rockets using pounds of propellant! I'd imagine less than an ounce would only take 1 or 2 milliseconds to burn. As long as the propellant is completely burned by the time the HVR exits the barrel, then spin stabilization isn't needed. Which is good, because the design isn't intended as a precision sniping weapon, but as a simple weapon of major power.

And, because the things are so fast, leading of moving targets is very simple...you don't.

If a pocket HVR was assumed to have an 8,000 FPS velocity, and an effective range of 100 meters, than a car moving across your LOS at 100 meters at 100MPH would only move 5 feet in the time it'd take the HVR to cross the gap. Aim at the passenger compartment and you're going to hit it.
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May 8th, 2003, 06:43 PM
Anthony
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VERY interesting!

To achieve such an incredibly short burn time, is the propellent a loosely packed powder ratehr than a solid grain?

I'm thinking of something (easily improvisable to start with) using empty CO2 capsules. Formed steel nozzle, with the nose filled with lead. It wouldn't hold 30kpsi, but even a fraction of 8kfps would be a mean toy to start out with
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May 8th, 2003, 11:45 PM
nbk2000
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The patent is 5,440,993

It uses loose SP. The flakes "float" on the gases created by its combustion, allowing for extremely rapid burning, but the rocket only works if it's moving. Reason is that the propellant grains inertia keeps it inside of the rocket, against the outflowing combustion gases, otherwise they're blown out unburned. So no static firing is possible.

Also, the large rockets mentioned in the patent (155mm anti-tank) burned their propellant charges in less than 2 feet of travel. This created:


Quote:
a large rearward flame was observed thus requiring that the rear of the launch tube be kept clear of personnel. In the case of firing from a gun tube, blast shields may be required for personnel protection.



A couple dozen pounds of SP burning in a few milliseconds? I bet THAT was a huge ass fucking fireball! Though the smaller HVR's would only have a fraction of an ounce, it'd still likely create a nasty fireball like that from a .50BMG, only larger. I'd think some way of venting the blast to the side would be a good idea, unless you build it as a bazooka type weapon that sits over the shoulder.

I don't think a CO2 powerlet would work, because the HVR design creates over 30,000 PSI of internal pressure, while CO2 tanks are burst rated to only 3,000PSI, below which they'll deform. I don't think a powerlet is even close to that.

Also, the design requires a nozzle that protrudes almost to the very front of the rockets internal chamber, to seperate the gas while retaining the propellant grains.
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March 7th, 2004, 02:49 AM
nbk2000
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During a recent google search on gyrojets, I found a site I've never seen before, www.deathwind.com .

Seems someone is trying to recreate the gyrojet.

'Course, they're going all about it all wrong. They're still trying to use gyroscopic stabilization through canted vents.

Tsk, tsk, tsk. Obviously inferior to my hybrid gun/gyrojet concept, the Gy2.

Interesting how they're using .50BMG full metal jackets as rocket casings. Might be usuable for improvisation.
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Related rocketry infromation

November 26th, 2003, 04:35 PM
Arkangel
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You want a high speed fuel for horizontally fired, flat trajectory projectile right?

Then forget Estes, forget any model rocketry you see on the Nakka site and elsewhere, they are ALL too slow burning. As Tuatara said, making things go faster involves burning more fuel in a shorter space of time. I've fire 66mm LAW's and RPG7's, and in both cases, the fuel is all burnt before the rocket leaves the launcher. There's just a big WHUMP and it's gone. I used to have a LAW motor kicking about, and it's a very strong aluminium body, with venturi something like half the size of the overall bore. The fuel is in the form of a load of thin rods. You could do that sort of thing with home made rockets, but you're going to have to forget everything you read about models - pvc/cardboard/rolled metal tubing and the rest. Your rocket will have to be made from a piece of solid metal, and in any case, I wouldn't dare fire something like that home-made from over your shoulder - you'll die sooner rather than later.
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December 1st, 2003, 09:52 PM
AsylumSeaker
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Arkangel- Basicly what I mean is a rocket which will be launched horizontally from a tube. Research I have been doing includes looking into ww2 rocket launchers, particularly the german panzershrek. I think I have the design of the rocket down how I want it, except what fuel to use. The question I was asking was what fuel would give me the highest acceleration which I could obtain or make without to much hassel, ie- without breaking into any sort of military facility. Thanks for your help. No need to ban me, I will leave now.
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December 2nd, 2003, 09:01 AM
Jacks Complete
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If I might make a suggestion.

Build a large crossbow. Fire your rocket from it, with a clever 1 second delay fuse on it.

I will leave you to figure out the rest. Then you can explain it to us.
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December 3rd, 2003, 03:42 PM
Arkangel
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In that case Asylumseaker (and I'm not a mod, so I couldn't ban you anyway), it's pretty easy to work out some parameters:

As Wild Catmage explains, fired horizontally your rocket will start accelerating DOWN at 9.8m/s/s, just the same as a bullet does.

In this respect, you should be able to make a simple table of how fast the rocket will have to be going to get certain distances from your launcher.

For example, if you want the projectile to travel 100m and drop only an 10cm,

The formula you need is s=ut+1/2atsquared

where

s=0.1m
u = starting velocity(0m/s)
a = 9.8m/s/s
t = the time you have to get the projectile the 100m.

I can't be arsed to work it out for you, but you should be getting the idea.

So, once you've worked out how much time you have, then you can work out the average speed for that distance, or the acceleration you'll need to give the projectile. With a bullet it's a bit easier, as it's easier to get the average speed - muzzle velocity is maximum, and it will only decellerate after the barrel.

However, once you've roughly worked out the acceleration you need, you can work out the thrust needed from the rocket and all the rest of it.

But I can save you all the trouble.

Forget it unless you can burn all your propellant in a fraction of a second. Motor design is going to be critical and pretty much beyond anything model rocketeers can achieve. Fuel type is less relevant than giving it the largest surface area you can. Watch a LAW being fired, close up. Have a look at the design and you'll understand what I mean.
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Begin post

I encountered nbk's pocket-HVR concept a week or two ago, and it's been bugging me ever since as perhaps the most powerful portable weapon the common person could get. A handgun sized weapon firing off rockets? I love the concept and the visuals! Truly nbk is years ahead of his time in inventiveness.

So, having scoured the Forums for information relating to the Gy2 (as Nbk named it in one post), I think it's worthy of fleshing out. I also included some basic rocket information for fleshing out the rounds that would be used, since that's probably the biggest issue with the design.

Nbk, correct me if I'm wrong, but what we're looking for is:
1) A small, hand-held HVR launcher design/modification
2) A HVR design that would fit (hopefully) inside the launcher
3) A warhead for the HVR (perhaps more appropriately moved to the HE/OE section?)

#1 seems rather easy to think up and create, since all it has to do is ignite the propellant of the HVR and remain intact for multiple firings. I'm of the mindset that our biggest issue will be the "remain intact for multiple firings", since small amounts of propellant burning at microsecond speeds tend to act just like an explosive, which when inside a barrel is bad. Very bad.

Nbk already said that we need high quality steels to withstand the massive pressures that using smokeless powder as a propellant would cause, as copper and other metals just tend to be weaker than required. However, as I think about it, I believe that the micro-explosions shattering barrels isn't as much of an issue as long as we make sure that we're using the proper amount of propellant. A little bit of research into smokeless powder should reveal what numbers we need to keep in mind for our rounds.

Flare guns might be what we look into here, as that's the picture I'm getting for it.

#2 is something that's not as easy to define, at least not for me. I've been envisioning the rounds as smaller versions of the round mortar shells that you can buy as part of mortar firework sets.
http://img208.imageshack.us/img208/78/artilleryshelliu3.jpg

However, I'm not sure that such a design would be either workable nor the best that we could get. Nbk, what were you thinking the rockets would be shaped as? Normal rockets, round "ball" shells, or something else entirely? We can learn something, and establish a good max-min-optimum range for the weapon, as Arkangel posted. Testing different types of propellants/shell designs would be best, that way we have a wide variety of ammo to use if/when these things are made.

#3 is the one that I think would be the biggest hazard of the development process. What explosive were you envisioning that could be fired (mostly) safely from a handgun-sized weapon, Nbk? Definitely not AP, too unstable. And it couldn't be ANFO or something like that that needs a detonator. I'm at a loss for what explosive would cut it, especially with the intended effects (taking out piggies, vehicles, etc.). Perhaps just a crapload of BP or something similar?

U.S. Patent 5,000,094 might prove to be of some use in this area, since it is the patent for an exploding shotgun shell.

Nbk's comments would be especially useful in this matter, since it was his idea originally, but any input would help.

The idea behind using an HVR is that you don't need explosives as your kill mechansim, because the rocket is going so fast that it's kinetic energy alone is adequate to ensure a catastrophic kill. :)

You know how a .223 bullet, pushed from a long barrel at its intended speed, explodes into a lead snowstorm inside a target, creating massive damage?

Now imagine a .800 projectile, with over 20x the mass, going at 3x (or more) the velocity of that .223 bullet.

Having a penetrator tip made of tungsten or DU, pushed at over a mile a second, you do NOT need explosives. :)

.50 caliber bullets going at only 2400 FPS cause human bodies to blow apart from hydrostatic shock.

I could only imagine the effect of an HVR on soft targets.

Concrete walls of less than Seigfried Line dimensions, and trees smaller than old growth redwoods, might as well be made of wet cardboard for all the protection they'd provide.

On anything more solid, like a car engine block, the penetrator will disintegrate during penetrating of the barrier, emerging on the other side in a cloud of incandescent shards of heavy metal death. either to act as a point-blank shotgun blast, or as a flamethrower as the particles burn in a fireball known as a "vaporific" effect.

Pretty much any modern DB propellant should do the trick. The main thing is designing the rocket to contain the pressure long enough to ensure the fuel is fully ignited, without holding it in so long as to cause the case to explode.

A rupture disc made of foil or sheetmetal across the nozzle holds it in long enough to ignite.

I had the idea of using the pinfire system for ignition.

A disc of thin sheetmetal covers the nozzle to keep out debris. A cone-shaped plug, of same dimensions as the rocket nozzle, is spring propelled through the disc, where the firing pin on the tip impacts an ignition primer held inside the rockets head.

Upon impact, the primer fires and ignites the fuel. It burns until it builds up enough pressure to move a lever inside the barrel that's at the tip of the rocket (what would have been the hammer in the original design). This releases the tension on the firing plug, allowing the rocket exhaust to push it back (recocking it) and off it goes.

The Gy2 round would have a normal driving band to engage a rifled barrel, and the breech is closed upon firing, so the chamber is completely closed. Only after ignition does the gun go recoilless. Though there's actually going to be some recoil, though far less than a gun of the same caliber.

The firing pin is a consumable item that'll require replacement due to erosion from rocket exhaust gases.

Hmm, same kinda idea I had kicking around in my head, but completely different approach. Mine was a slow burning fuel in a simple metal tube. A large countermass is blasted out the back, a small saboted bullet is shot out the front. The fuel is slow burning to keep pressure down, so the barrel can be somewhat thinner and therefore possible to carry. But that is not a rocket, although the end result of superior firepower in a lightweight package is realized.

Anyway, thoughts on the Gy2 idea.

To initially launch the shot, the end of the nozzle can be closed off with a bit of sand countermass and some loose NC, which blasts the sand out the back. This causes the rocket to be moving forward when the main fuel begins to burn and accelerate the slug.

Making the round a sabot would allow greater range, since imperfections in the rocket motor are no longer significant, and drag is greatly reduced. The rounds are large enough that our high density penetrators can have fins to keep them going very straight. This will even out any slight unevenness when the sabot seperates, but will also do away with the need of trying to rifle the barrel.

I feel electronic ignition would prove to be easier than mechanical for reliability reasons, I doubt a mechnical trigger as you describe would last very long. Electronic would last as long as the batteries do, which will be a long, long time. I wouldn't go piezo since then there is a risk of the rounds being set off by static.

As for the launcher, I am envisioning a revolver style reloading system, with the barrel extending out the back so it rests on the shoulder. This gives a recoilless, multi-shot weapon, with no complex mechanical components beyond the ammunition, which IMO will be the hardest part to actually make.

The main disadvantages I see with the idea:
-Expensive ammunition, that is also bulky and HEAVY
-Backblast prevents use indoors (so you need to be in a fairly open area)

Jeez, nbk, ever thought about getting into advertising for defense contractors? If I was a general, and I heard the vivid and oh so accurate description you just gave for HVRs, I would order a few $billion worth.

There are caseless ammunitions under development that use a polymer binder to dilute explosive materials enough such that they burn at the appropriate rate. The projectiles can both be conventionally propelled by an initial propellant charge, and subsequently propelled by the burning polymer matrix. This is a safe(r) way of handling a potentially explosive rocket like propellant. Once ignited there is nothing that can stop the process, but at least it will not explode in the barrel.

The polymer acts as an inert (or energetic if you get something like GAP) diluent to slow down the rate of combustion just enough to keep it from exploding. A suitable high explosive could be used in this manner to create extremely powerful thrust in a short amount of time. Think of this as being just short of a detonation.

It would also be possible to gradiate the content of propellant. A low amount of explosive with a high amount of binder could withstand the initial shock of being fired, followed by an increasing ratio of propellant to binder the high up it burns.

I've thought about the possibilty of using existing ammunition cases as rocket shells.

Take a straight-sided rimmed cartridge case, enlarge the primer hole, notch the rim so it'd engage an exaggerated rifling, and insert the nozzle/fuel/HM tip to finish the round.

Use existing ammunition components as much as possible to simplify change over to the new weapons and preserve the capital already invested in legacy systems. ;)

RTPB: Imitate, then innovate.

Ignition could be through high-voltage current passed through the casing and a contact against the HM warhead, which is insulated from the case by a thin insulator.

I really need to sketch this out...

As for pitching it, I've read a lot of military sales pitches over the last 25 years, so I'm conversant in the phrase-ology to use, and have had some discussions in the past with Oerlikon Contraves on other matters. That was enough to sour me on expecting any integrity from those thieving fucks. :mad:

Tungsten powder loading in an ABM as a less-lethal weapon? MINE!

I doubt the casings would stand up to the pressure present in this situation however. Normally, they have the receiver of the weapon to take the pressure, in this case they need to travel down the barrel without expanding. Since the casings expand when fired I doubt they would be functional in this situation of 30,000psi.

Obviously, they would for normal rockets, but not the nearly instant burning ones we are thinking about here. Although, one could use the casing as an outer case to ensure that all rounds are the same outer diameter, and reiforce the inside to take the pressure with some steel. Might be me trouble than it is worth though... I'll have to think about it a bit. But I'm a little skeptical that one could imitate much when using a completely new weapon system.
Since we innovating somewhat, it makes more sense to me to make the innovation as good as possible, so that it's maximum possibilities are reached. Although it would be more expensive to produce than a design based on existing weapon systems, it will outperform such a "watered down" design by hopefully a large margin.

Oh, I know brass won't take the pressure of an HVR type projectile, but what about just normal gyrojet-type velocities? Those didn't move much faster than a pistol bullet, and had lower internal pressures than a firearm, so case expansion shouldn't be an issue.

Also, making it somewhat more similar to existing weapons would be an assest in selling it to the military, which is a highly conservative institution when it comes to anything new and unknown.

Thanks to the new hydrogen economy, considerable research is being done on high pressure storage containers made of lightweight composites capable of withstanding tremendous pressures. There are already 10,000 psi containers available, and these have been hydrostatically tested to burst over 23,000 psi. These containers are intended to be as light as possible for automotive use. I am sure with a bit of additional material a much stronger container can be built, albeit heavier

Given 10 years there will likely be mass manufactured composite materials and containers capable of even greater pressures. At such a time, off the shelf technology could enable the custom manufacture of devices suitable for our needs rather inexpensively.

Quantum Technologies has a “low cost” tank now under development that has a burst pressure of 27,510 psi. That’s just a small hop from 30k psi, and their primary focus is making it cheap cheap cheap.

Ah, ok, my bad there NBK. I thought that you where talking about HVR type projectiles, since you had just called gyrojets a thing of a past a few posts ago.
Personally, I think they are too hard to make perfect to be of use without a very large investment in a lot of high precision tools.

Mega: lightweight is good! The rockets will outperform steel ones, even if a "heavier" material is used. It's still going to be a lot less weight than with steel, which translates into a greater kinetic energy imparted to the projectile.
I think it might be possible to make something similar these days, with a bit of ingenuity and a very thorough literature and patent search. I imagine most difficulty would come in the actual processing procedure.

Since we innovating somewhat, it makes more sense to me to make the innovation as good as possible, so that it's maximum possibilities are reached. Although it would be more expensive to produce than a design based on existing weapon systems, it will outperform such a "watered down" design by hopefully a large margin.
Right now, I think the purpose of re-arming existing rounds is to work out some of the rougher kinks in the process, as well as to allow for a better secrecy in the process, since lots of gun-fanatics (not a bad thing) reload their own ammo, but not many people make their own from scratch, even within said fanatic sects.

For that matter, comparatively, it'd be cheaper to reload existing ammo to test the principles involved than to design, test, and make an entirely new type of ammo. Plus, reloaded ammo is completely legal. New types of ammo are a grey area as far as I know. Besides, why get rid of the old designs? Bullets are the way they are because there have been enough tests to dictate that their design is the best for it's purpose. Plus, the old casings can be found everywhere. Go down to the local shooters club or something.

Back to the Gy2, I was looking up hydrostatic shock (no pictures of course), and I came across a statement that made my brain twitch: at 8000fps (5454mph), the rocket is going to be going Mach 7 (assuming a 758mph sound barrier), which means even though there's no real muzzle flash or recoil, there WILL be a loud crack as the round goes hypersonic, which might give things away to those that survive such an attack. All three of them. :D

Also, is there any way to increase the burn speed of double-base/triple-base powders (thereby increasing projectile velocity) aside from the 'floating powder' method contained within the patent that Nbk gave (5,440,993)? A quick Google search gave me these ways, but there's a major issue with them.
The burning rate of smokeless powders is varied and controlled in various ways. One is by the physical size of the grains, flakes, or spheres of powder. The larger these are the slower the powder burns. Naturally, the exact chemical composition of the powder also affects its burning rate.

A third method is to increase the surface area of the powder grains. The individual grains of many cylindrical powders, for example, are hollow rather than solid cylinders.

Another way is by the use of deterrent coatings to slow the burn rate. These coatings retard the initial ignition of the individual powder grains. They may also decrease the burn temperature, which reduces throat erosion in firearms.
Obviously, the only way we can control these is to make our own smokeless powder, which isn't worth the effort involved in this case. Unless we intend to open up a small factory to make the stuff in large quantities for public sale, it's not worth the effort.

This leaves us with one option at this point: shop around and see which smokeless powder burns fastest. Preferrably, it would be the smallest flake size we could get, with a very small amount (if at all) of deterrent coating, compressed to a very high density.

Considering the apparent difficulty in finding such a specialized powder, it should be obvious why I asked about any other techniques for increasing burn rates. I've been reading like a maniac thanks to some PDFs on the FTP that talk about propellents, so hopefully I'll come across something if you guys don't have something to help in this case.

I see this as almost enevitable unless the sale of reloading DBNC is restricted. In the HVR patent they use larger grain stuff as you would in a normal 3 inch gun so it follows that some grade of powder you get at the gunshop would work for a smaller version.

Megla's idea about the new composite materials is great. Really all the mass should be in the DU or W rod out in the front. It seems wear and tear on the "rails" system would be horrible so perhaps little teflon feet on the pegs could be used.

I am talking out of my ass here but it seems with a simple "ball and cup" type of sabot the seperation issues would disappear. The Rod is inside a thin steel tube lubed up with some sort of telfon grease and held on by a very minor crimping at the tip. The steel holder tube is what is attached to the rocket part. It fired and then as it comes out of the barrel the air resistance slows down the tube and rocket part and the KE rod just sort of slips out - thus no 3 part sabot that could kick the rod to some strange direction.

I may have a chance to work with a small metal lathe in the coming year and I might be able to make a very crude mock up following the HVR patent out of aluminium metal.

The one thing I don't get is how can we get it to fire without it moving? It was my understanding that the grains have to get all shaken up like grain dust in an elevator before it can be fired.

Great thread!

Could use the same idea used in missiles, of a booster-motor, to get the projectile moving in the barrel.

A booster propellant pellet attached to the base of the HVR is ignited by a primer. The booster and a portion of the HVR sit in a 'cup' that holds the firing pin that'll ignite the primer that fires the booster.

When the primer is fired, the booster pellet ignites the HVR propellant, while also pushing the whole HVR rocket out of the 'cup', giving it the needed initial velocity for the HVR propellant to burn, with minimal recoil.

Or, as shown in the attached drawing (MS paint, sorry), a Gy2 projecticle has a pressure disc (blue) sealing the open end, with a side-mounted primer (red) and a booster pellet (orange) inside of it.

When the primer is fired, the booster pellet burns inside the sealed rocket, igniting the main propellant charge and pressurizing the casing to the rupture point of the sealing disc.

At this point, the rocket is pushed on its way down the barrel by the venting booster gases, the propellant in the rocket is burning, and now has the needed momentum to 'float'. :)

As for the rails, they don't have to run the whole length of the barrel, where they'd be subjected to the friction of a 10KFPS projectile pushing against them.

The rails only need to be long enough to impart the needed spin for stability, which is the first few inches, which would be subject to a much lower velocity (though still gun-speed).

Well, I can tell you the fastest propellant I know of is Red Dot, which is about 80 to 90% nitrogylcerin. It burns plenty fast for most uses, and far too fast for most. Any powder manufacturers site will have a list of tables.

As regards using a case, that might be a bad way to go. Instead, get a bullet head, standard copper jacket and lead core, military type with no exposed lead tip. The jacket is 90% copper, so very tough, and, importantly, it is also the right shape!

Get a fireproof mat and a blowtorch, and heat it up until the lead core drops out. Allow to cool. Your copper shell will be much better shaped for firing things than the case.

Note that it might screw with the hardness/softness of the copper, so try either quenching one or letting one cool slowly, then comparing them. Use whichever you feel is better.

I may be wrong (wouldn't be the first time), but I thought Bullseye had the highest nitrogylcerin content at 40%.

Dont forget that the barrel/launcher tube is going to have to withstand a few hundred (maybe thousands) of degrees. Perhaps have a standard barrel with a replaceable internal sheath (made of some special alloy?).

Might help, but it depends on if you are going to use rifling, etc., as to the practicality of this.

Most modern barrels have to regularly handle such temperatures, thanks to smokeless powder's wide usage. Nothing new, obviously not that hard to handle. What we really need is a barrel that can withstand the pressures that we'll be subjecting it to in the space of about a microsecond.

Like nbk said somewhere up the top how we could use revolving drums.....perhaps if we made them strong enough to handle the pressures than we wouldnt have to worry so much about the barrel, otherwise we would have to have a "chamber" at the start of the barrel which has been reinforced.

Just a thought.

The magazine only holds the round, not acting as a pressure-bearing chamber for the round, which is self-containing in that aspect, unlike conventional firearms. :)

Indeed, wolfy, you should re-read the thread. The round is a hyper velocity rocket that generates most of the thrust by continuing to burn propellant AFTER it is fired from the gun.

Wait a second Mega, I thought the concept was to generate the massive thrust needed to attain supervelocity by burning the entire load of fuel within the space of about a microsecond. That's the entire premise of not needing fins or anything else, just a basic cartridge. If the rocket round is still burning fuel after leaving the barrel, then we're back to the old problems with fins and stabilization, all the crap we thought we'd get rid of.

Either way the barrel is not subjected to large pressures. Both ideas are being discussed here, although it is causing some confusion so perhaps the thread should be split since both concepts are different enough to warrant it IMHO.

Whether or not the fuel is consumed while the HVR is still in the barrel depends on the size of the propellant charge and the length of the barrel it is fired from.

A small charge with a long barrel will completely burn within, while a large charge in a short barrel will burn after exiting.

The ideal would be to have as much propellant charge as possible within the HVR as will burn within the barrel length the round is being fired from, to provide maximum velocity with minimal drift.

This means pistols would have lower velocity than assault cannons, because of both smaller caliber and correspondingly lesser propellant charges.

Now, nothings to stop someone from firing a large caliber projectile with a large propellant load from a pistol, except for the fact that the resulting jet of flame from the HVR, as it continues to burn after exiting the barrel, will incinerate the hand that fires it. :p

This weapon seems to be becoming more complex as it is discussed and not very DIY achievable but as a millitary application and as it is a future weapon why not use a futuristic propellant?

I was reading about a new range of explosives proposed as a rocket fuel using the all nitrogen dipentazole (N10). I do not know about the burn rate of this compound but you can probably safely say it is very high.

I am also a bit confused as to wheather the rear end of this weapon will be capped. If it isnt I dont see why the barrel needs to withstand such high pressures but you would also lose a lot of the potential thrust? as well as having to deal with a large blowback. However if the end is capped then the recoil would be just as high as any standard firearm with the same kinetic energy round which would be very high for a weapon with this suggested muzzle velocity.

Why not go with a "soft launch" system, a la Javelin anti armor missile? An initial charge of powder in a divergent section of laval nozzle, small delay charge in the pressure section, and main charge in the chamber. Keep the breech closed, but place large vents midway down the barrel. Effect could be tailored to be similar to a shotgun's recoil initially, with HVR effect coming on 3/4 distance down the barrel. Small vanes in the exhaust (immobile versions of guided missile directional vanes) would impart spin. Cap it all with a primered cup at the end of the laval nozzle that separates on firing. Not exactly caseless, but close, with very small cases similar to what an M-1 tank spits out.

Come to think of it, shotshells minus the plastic could probably be used quite easily as the base!

This weapon seems to be becoming more complex as it is discussed and not very DIY achievable but as a millitary application and as it is a future weapon why not use a futuristic propellant?

I was reading about a new range of explosives proposed as a rocket fuel using the all nitrogen dipentazole (N10). I do not know about the burn rate of this compound but you can probably safely say it is very high.

I am also a bit confused as to wheather the rear end of this weapon will be capped. If it isnt I dont see why the barrel needs to withstand such high pressures but you would also lose a lot of the potential thrust? as well as having to deal with a large blowback. However if the end is capped then the recoil would be just as high as any standard firearm with the same kinetic energy round which would be very high for a weapon with this suggested muzzle velocity.

1) The weapon was always complex, as is the design of any form of new weapon. Essentially what we're doing is the same as what design teams did when they started designing handguns. The only difference is, they weren't designing a weapon of this level of nasty. The DIY application was based around distributing a mold and a wax model of what the final product would look like. No-one ever said it'd be easy to do, but just like making a firearm of any kind, you can do it at home if you know what you're doing.

As a sidenote, what about using rapid prototyping (http://en.wikipedia.org/wiki/Rapid_prototyping) for the production? Then all we'd need to distribute would be the CAD design or such through the site, and then members could have their machine make it at home in just a few hours. Of course, the machinery involved will be out of reach for most people currently, but since they're working on making ones that can make copies of themselves, soon enough they could be everywhere.

2) dipentazole and other related compounds are still theoretical at this point. They have yet to actually produce them. All they've got are quantium-physics models and such. But yes, if we were to pursue such a high-power fuel in the future, that would be a good candidate.

3) Yes the barrel will be capped on the end. The very simple reason is that the user doesn't want to be engulfed in a nasty jet of fire exiting from the weapon's backside. The Gy2 is meant to be a portable, handheld weapon. However, the method of propellant would produce almost no recoil, which if you had paid attention was mentioned in the archival posts repeatedly.

Returning to the Gy2 (which is hard, because Rapid Prototyping is so blasted interesting), I'm slightly confused now, probably because of my serious lack of firearms physics knowhow. In most firearms, the barrel of the firearm is easily able to contain the gradually increasing pressure placed on it by a fired round. Sometimes if there isn't enough SP in a bullet, it burn fast enough that the pressure increase is like a micro-explosion inside the barrel, which causes issues and damages the barrel.

This seems like it would be the exact problem with microsecond burn times, in that it'd be a microexplosion inside the barrel, hence why I've been touting a high-pressure resistant barrel or something to prevent the barrel from exploding on you once it's been used once. While placing the pressure bearing problem on the casing itself, I still think this would be a problem. What am I missing in this equation Nbk? You don't seem to be bothered by it at all.

Chances are, my inexperience is forcing me to overlook something really really basic.

Well, like all things, there's a compensation for all that power that the Gyrojet has. Yeah, it has more thrust than a bullet, and can penetrate all body armor, steel plate, concrete etc. But at close range it's useless. To generate the thrust, it needs to build up speed. A weapons author on a History channel documentary (I believe it was Ian Hogg) stated that you could stop it at the barrel with your finger, or just step out of its way. It's not the perfect weapon by any means, but if you're speaking strictly long range, then yeah, go for it, because it is a badass weapon.

The original Gyrojet had that problem because the propellant was still burning long after the projectile left the barrel.

The Gy2 does not have that problem, because all the propellant is burnt while the rocket is in barrel, and the rocket is restrained from moving until it reaches full thrust.

Then the frame better be made of some tough stuff, like titanium or some other material that has a high tolerance for the temperatures a gy2 is going to generate. Even though, I still like the idea.

Why not approach the problem a step at a time? For instance, what if one were to modify a conventional bullet to be a rocket propelled round just to experiment with the particulars. Such a round would have a higher velocity exiting the barrel, but would still be a far cry from the desired object. Subsequently, building upon this design, modifications can be made to scale up the device.

I prefer to solve an experimental challenge one variable at a time, initially ignoring the lack of desired results to get one component operational. I usually end up with what I want if all the parts work like they should.

I am not particularly mechanically inclined, so I will put the question to the more knowledgeable on The Forum. What initial first step would you make? Would it be figuring out how to make a rocket thrust cone out of a bullet? To determine how best to initiate the propellant? Where to begin?

The original Gyrojet pistol was made from Zamak, a cheap zinc alloy. I've seen one taken apart and it reminds me of my old Mattel six shooter. It only served to ignite the rocket and send it in the proper direction. No structural strength was needed. I was lucky enough to meet the orginal designer some years ago. He told me that the hammer spring was adjusted to provide a slight brake which allowed the rocket to build up pressure before it took off. Also kept it from sliding out the barrel, which frequently happened with the old hammer set up which hit the primer from the rear as with a conventional firearm. Used a modified DB propellant and were spin stabilized. The angle vent holes provided this spin. Somewhere I have a list of the applicable patents. I'll see if I can dig them out if you wish. In the mean time, check out- http://www.deathwind.com/project.htm . It has some additional info, even though judging from his photos. I don't think the guy is legit. BTW, Bob Mainhardt, the guiding force behind the project died last month.

"To paraphrase Aristotle, life is a gas!"
-Gidget

I remember the original magazine article (Guns magazine, maybe?).

The major complaints at the time were : Expensive ammo, low power, and less than spectacular accuracy, contributed mainly to a long "lock time" due to the rocket being slow to develop thrust as compared to smokeless ammo.

These same issues are still stumbling blocks. Seems there's little the 'Jet can do better than conventional firearms.

Except- launch a 75-plus caliber projectile from a hand-held weapon. If a gyro type gun is to be successful, it needs to do something that other guns can't.

With the inherent "soft launch", recoil isn't a big concern. So, go BIG!

The major complaints at the time were : Expensive ammo, low power, and less than spectacular accuracy, contributed mainly to a long "lock time" due to the rocket being slow to develop thrust as compared to smokeless ammo.

These same issues are still stumbling blocks. Seems there's little the 'Jet can do better than conventional firearms.


Those might still be problems with the original gyrojet and things of roughly the same size, but the Gy2 is quite a bit different than the original or anything similar.

Problems:
1) Expensive Ammo - Depending on what we finally use for it, this very well might be a non-issue.
2) Low power - The only thing that'll out-muscle this is either artillery or emplacement weapons, and that's iffy. Definitely non-issue.
3) Bad accuracy - A non-issue, as all propellant is burned within the barrel. The only real drift there will be is by wind, and even then not really. No more than a normal bullet, or perhaps even less due to it's speed.

Mega - While I'm no expert, my first suggestion would be figuring out how to get the thrust up to speed, since that's the most important part of the weapon. After all, KE is the sole cause of death. After that, ignition is probably next most important.

Of course, we also need to figure out what we're going to use as a barrel for these testings before we do anything else. Don't know about you, but I sure as hades don't want to be firing a HVR round in a normal handgun. Do you?

I was talking to a physicist today about artillery weapons, and he mentioned the largest caliber weapons really only have a practical range of 18 Km at a velocity of about 500-600 m/s. Beyond that velocity the drag becomes excessive to the point scaling up the guns is wasted effort. And here I thought all physics problems neglected air resistance (physics students will understand that joke).

This makes me wonder how big you would have to scale a small caliber weapon. I know there are missiles that travel at extreme velocities, but they are scaled up appropriately. Anyone feel up to calculating some “back of the envelope” drag equations?

There's no need to do them by hand. Go to the ammoguide ballistics calculator, or download a ballistics calculator from somewhere. They will tell you how fast a projectile slows down, so you can then work out the drag, as it is the only retarding force.

We only care about the drag in the first moments after launch of a regular bullet, as this will be the end of the burn phase of the round. Work out a target max velocity, then plug that in. Set the calculator to tell you the speed at 0, 10, 20 30m, then do a little maths.

Of course, the main thing this will tell you is that you want a heavy projectile going fast with a good ballistic coefficient, which isn't what you will have from a gyrojet type round. You want the minimum of retained mass after burn-out, since the propellant should send it a good 300 yards before burnout anyway, and it should do that in a fraction of a second, just the same as a regular bullet would.

I'd model it on the CheyTac .408 round. You want a good knock-down and long range, and the bullet is plenty pointy. I've just run some figures, and it turns out that the BC is the hardest thing to work out. Plus, our BC would change during flight. Some numbers that really don't mean much:

(All in feet per second at muzzle, 100 and 200 yards)
Velocity for pointy 419gr (BC 0.903) -the actual CheyTac round
0 . . . 2890
100 . 2784.5
200 . 2681.5

Velocity for flatnose 15gr (real flatnose lead bullet at .430 cal.)
0 . . . 2890
100 . 2445.2
200 . 2042.3


Velocity for fictional 0.05 BC hypervelocity round
0 . . . 4500
100 . 2334.5
200 . 1086.4

From this we can see that light things that aren't pointy don't retain velocity very well. But that's about it.

If the propellant was to be burned entirely inside the barrel of the gun, you may just as well have a huge powder charge behind a normal bullet, the recoil would be the same. The reason that the Gyrojet had vey little recoil is because most of the propellant was burned outside the barrel, while the round was in flight. What I was suggesting is a hybrid. Fire the rocket out of the barrel with a standard rifle/shotgun charge, and (with a delay charge) when then rocket has cleared the barrel, it fires the booster to get up to operational speed. What you wind up with is acceptable velocity at close range with phenominal velocity farther out, and acceptable recoil.

A rocket and a recoilless gun are not the same thing.

A R.G. requires a much larger amount of propellant than a rocket, as the mass of the propellant gases in an RG acts as the countermass for the RG projectile.

The Gy2 would have a rifled barrel, but that's not a true rifling, like with a conventional firearm, where the barrel bites into a metal driving band.

Instead, it's a stud in groove, like an MLRS or Armstrong projectile, with the studs either being integral with the projectile, or part of a discarding sabot.

Since the studs are loose when riding in the groove, there's not much friction to cause recoil or torque. :)

O.K. I get what you're saying. I was still thinking of how to use a standard looking firarm (shotgun) with a modified yet somewhat standard looking (shotgun) round using an HV rocket instead of a slug. I didn't realize you were talking about an open breech.

just a thought, if possible you could coat it in teflon or something similar to further decrease the resistance the barrel has with it. I know teflons hard to work with, so maybe we could find something similar to use.

I have a similar idea based upon the rocket assisted 120mm howitzer round except it will act more like a standard 40 mm grenade.

The launcher would be similar to the assault shotgun, which was found via Shareza, modified to handle the length of the round. 12 gage, 5 round detachable magazine, 30-34” barrel with light rifling, flash hider, and a scope.

The round is 12ga rocket assist round based upon the howitzer’s 120mm rocket assist round. Primary difference is the 12 gage round utilizes the same primary propulsion system that the 40mm grenade launcher utilizes and secondary mechanical ignition of the propellant in the carbide tipped rocket.

Performance intent is 350-400 fps mv, with a delay long enough for the rocket to be roughly 5-10 m from the muzzle.

I still need to work out all the characteristics regarding propellant, rocket length, dynamics, and stability

Not sure Teflon would help. Teflon coated bullets are actually slower, because the build-up of pressure is lower behind said bullet when a round is fired.

Appreciate the info.
My first scale rocket launch was a disaster, flew like a drunk dog on ice. I need to go back to the drawing board on balance.