Is this real?


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KriegHund
July 2, 2005, 09:44 PM
http://www.defensereview.com/modules.php?name=News&file=article&sid=526

Kinda interesting.

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UberPhLuBB
July 2, 2005, 09:57 PM
It is but it has a number of issues that will probably never be hammer out, most notably it's "shotgun" patterns from very short distances.

There exist no photos, videos or any kind of description of the mechanism though.

It's like that 1,000,000 round per minute "gun" which uses stacked ammo. It has interesting numbers but no practical application.

Cesiumsponge
July 3, 2005, 02:39 AM
That Dread thing has been kicking around for a long time. The video shows computer graphic representations of what it is supposed to do with cheesy explosions and animations. It also shows brief footage of a (likely scaled down) prototype shooting three horrible shotgun patterns on paper about 3:51 into the video that get progressively looser. They claim noiseless but you can clearly hear noise in it. They should put in on Penn & Tellerís Bullship! At least Metal Storm doesn't make physically impossible claims even though its impractical.

Iím going to throw out some numbers, obtained in SI but converted to units familiar to most of you here. I havenít done physics in a long time so I probably made an incorrect assumption or forgot to "carry the 1" somewhere so if anyone cares to check mathematics on a Saturday night for me :neener:

Imagine a gun with no recoil, no sound, no heat, no gunpowder, no visible firing signature (muzzle flash), and no stoppages or jams of any kind
Even if it becomes necessary to increase the DREAD's magazine capacity to upwards of 100,000 rounds (.308 Cal.) or 20,0000 rounds (.50 Cal.), and run the weapon all day and all night for weeks on end, this will have absolutely no effect whatsoever (positive or negative) on the reliability or durability of the weapon system.
The DREAD is both heatless and frictionless, and doesnít generate any high pressures. So, thereís virtually no wear and tear on the system, no matter how many rounds are fired through it back-to-back, even if it's run constantly on full-auto at 120,000 rpm, the whole time.

First three claims break the laws of physics. You can cheat recoil using various dampening methods or using a recoilless rifle design (ie not restricting gas expansion) but saying no recoil period is unfounded. Heat is produced with any type of friction so unless you're operating in the deepest vacuum of space (and there is still friction) or youíve got a jar of superfluidic Helium-3 at a few billionths of a degree above absolute zero, no dice.

No sound? We must be led to believe the drum spins using some sort of soundless electric motor and that all that ammunition that needs to be accelerated in this spinning device won't make a sound. The thing appears to use angular momentum to fling BB's out so with the firing of these BB's, there will be a reduction in rotational speed of the drum due to ejected mass (the projectiles), or you will greatly increase the loading on the motor to the point of overheating. When you start making claims that it can fire at 120,000rpm, any reasonable motor (in a supposedly man-portable device) cannot keep up with that demand. Imagine the power source it needs.

For the sake of argument, these BB's are .30 diameter of generic steel. Itíll give us an approximate mass of 74 grains each knowing the volume. Since theyíre dimpled, we can call it an even 70 grains. 2000 rounds fired over one second at 120,000rpm (rounds per minute, not rotations), thatís a mass of 21.1 pounds of ammunition fired per second, or .63 tons per minute. You need an innovative hopper design to feed that much spherical ammunition single-file, without jamming. The cited velocity is 8000fps in open air with no chemical propellant, which is an incredible 1.5miles per second. Lets make a kinetic energy comparison:

A 147-grain 7.62mm NATO at 2700fps has 3225 Joules of energy
A 70 grain dimpled steel BB traveling at 8000 fps has 13481 Joules of energy

While it weighs less, the BB is traveling much faster and has over 4 times the energy than a .308. The formula used to obtain energy is KE=. 5mv^2 where m is mass and v is velocity. Velocity is squared while mass is always one half the value. One can see you can get energy much faster by increasing velocity. By using half the weight, but about 2.5x the velocity, we more than quadruple the energy.

13500J of kinetic energy is a LOT, right under the .50 BMG in terms of muzzle energy. Over a period of one second, it will deliver 27MJ, or 27 million joules of energy, enough to keep a 60W light bulb lit for 314 days nonstop. I find it impossible to believe all this delivered energy will cause NO HEAT unless it took place in BizzaroWorld.

A-10 Thunderbolt pilots will tell you that when they fire that GAU-8, their plane physically slows down from the cumulative recoil force from firing the monster. Itís documented by first hand experience, and can be retold with simple physics.

We can get the force produced by measuring impulse over time. Weíll get 84 lbf.ft/s, which is force in pounds. The force we get over a period of 1 second at maximum feed rate, which is 2000 rounds a second, is consequently 168000 pounds, or 84 tons of counteractive force needed per second. The motor will need 84 tons of force to counteract the recoil force of the projectiles on the spinning drum. Thatís just to BREAK EVEN. It needs significantly more to spin at who-knows-how-many-rotations-per-minute to fling BBs out at 1.5 miles a second.

Granted, this is an angular momentum problem and we donít know the diameter of the ďdrumĒ that spools up the rounds. However, you can be damn sure your ceiling fanís electric motor isnít going to be able to keep up with this. I canít imagine any reasonably man-portable electric motor that can exert that force. Even if you can, think of how much power it needs to consume.

27MJ per second of kinetic energy impacted on the projectile. Assume the device is (impossibly) 100% efficient in energy transfer; we need to flow 27MJ/s to the magically compact electric motor which will transfer to the projectiles at a 100% magical efficiency rate. A watt is measured in joules/second. Simply put, itíll take 27megawatts from a generator or battery bank to power this thing. To get an idea of that, an 800 cold-cranking amps battery operating at 12V will put out 9.6kW peak. We need 2813 batteries to get equivalent energy consumption. A 800 cold cranking amps rated battery will operate at 800 amps for a handfull of secnods before itís dead.

Also, in the real world, electric motors arenít 100% efficient. Operating at a higher voltage to minimize resistive losses, lets say the motor they use is 90% efficient. The remaining 10% has to be dissipated as waste heat. 10% of 27MJ is 2.7MJ. 2.7 MJ of heat has to be dissipated per second to keep the motor at a stable temperature. You can provide a constant flow of 2.3 gallons of water at room temperature, per second over the motor, and it will come out the other side boiling. Consider energy and heat from a 60W bulb operating continuously for a little bit more than a month, but condensed into a secondsí time.

We can also address the issue of aiming the device. A spinning drum with the incredible features mentioned above will have gyroscopic inertia. Everyone here has played with gyroscopes before. Now imagine the energy required to tilt a device like that above given all the energy figures.

A high school physics teacher could pick apart all the either inaccurate numbers, or impossible claims

GregGry
July 3, 2005, 03:13 AM
Hahah awesome post Cesiumsponge, you saved me about 2 hours worth of figuring and writing. I have never seen that before, but I don't see how its possible. Their claims are huge, I don't see how they are going to get the power to do it. Even if they have an electric motor that can handle the load, good luck trying to feed it the power it needs. The only way I can see that thing actually working, is if we can figure out how to make nuclear reactors small enough to fit in a trunk, and electric motors the size of a small coffee can, that can output in excess of 30 hp.. If it was powered by a 140hp motorcycle engine, I might believe it more, but not using electricity..

Selfdfenz
July 3, 2005, 03:23 AM
When this came up a month ago I thought it was probably bogus. Having watched the video I'm actually even more convinced this company has no payload.

The concept seems nearly impossible but I'm willing to say if it can be pulled off it could be a neat tool. I just don't think this comapny has it.

"the prototype had to disassembled for security reasons"

Yeah sure.

S-

Joejojoba111
July 3, 2005, 03:43 AM
Metal Storm has a use, some countries use rapid-fire artillery pieces, they unload a lot of ammo fast and then get the hell away from where enemy radar has positioned their location to be. Metal Storm would make their guns lighter and their missions faster. Just saying.

hcker2000
July 3, 2005, 03:45 AM
I don't know about that system but stacked ammo is a reality. If you have never seen http://www.metalstorm.com/ you should as it is absolutly amazing. It puts mini-guns to shame.

Cesiumsponge
July 3, 2005, 03:50 AM
Here is the actual US Patent they filed:

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=6,520,169.WKU.&OS=PN/6,520,169&RS=PN/6,520,169

If that link doesn't work, type in this one: http://patft.uspto.gov/netahtml/srchnum.htm

and put in "6,520,169" in the search query.


A few people on Defense Review already tore up the idea. Here's a following quote from one member that had access to MATLAB or FEM or some fancy program:

As much as I believe that the "150 watt" power supply is dubious and 120,000 spm is misleading, these little trifles don't compare to the greatest flaw of all in the system...the ammunition.

Its all well and good that the DREAD can out ammo at 2500-3000fps, but how much of that energy actually reaches the target. I ran some computations using a ballistic analysis system. What I found was horrifying...to the Dread.

My calculations for the ballistic coefficient of .308 dimpled tungsten balls arrived at roughly .055. A .308 smooth lead ball (44 gr.) has a ballistic coefficient of .043 (just for comparison). Obviously, the BC changes with velocity, but .055 is a good, and fair approximation of the BC. So a .308 tungsten dimpled ball would weigh about 50 grains and would have 999 or so ft/lbs muzzle energy when traveling at 3000 fps. Not bad until I saw the results under STP (Standard Temperature and Pressure). By the time it has reached 25 yards, its velocity was 2579 fps and ME in ft/lbs was 738. At 50 yards: 2195 fps and 535 ft/lbs. 100 yards: 1537 fps and 262 ft/bs. 200 yards: 914 fps and 93 ft/lbs. 300 yards: 711 fps and 56 ft/lbs. At 300 yards it has dropped 84 inches. those results are very telling. At 300 yards, the projectile would have as much stopping power as an airgun (albiet a VERY powerful one). The poor penetrating power of spheres (the USS Constitution and eary iron clads can attest to that) only adds insult to injury. Even if you boosted velocity to 5000 fps, the projectiles would only have 88 ft/lbs of KE at 300 yards. Do the math, and you will see the truth. The Dread is Dead. There is no way that the military is going to deploy a weapon sytem that is SO INEFFICIENT in ballistics test, and ultimately killing power. Muzzle Energy is one thing, but terminal energy is another.


711 fps and 56 ft/lbs at 300 yards :rolleyes: Not completely harmless, but hardly seems like it'll do more than make annoying pinging sounds to those inside vehicles.

snuki
December 28, 2006, 07:45 PM
Some of the claims they're making are impossible.

But when someone quotes a firing rate like that they mean 'if you could shoot for a minute straight' it's the same thing as saying that it's 1/120000th of a minute per round. (1/2000 of a second)

The post middy points to makes that mistake then goes on to calculate the power required.. but really what you need is average power. The average power input will decide how quickly you can follow up one burst with the next.

lets say you wanted to be able to sustain 200 rounds per minute. About the same rate you shoot with a regular machine gun (note that the firing rate of machine guns is usually quoted around 1000 rounds per minute for the same reasons). At 13.5kJ per round, that would take.. (13 500*200)/(60*745)= 60.5 Hp, not counting losses.

This is a much more reasonable, but still a little silly considering that A military hummer is 150 Hp. So once you factor in friction it could use most of the engine's power output. So you could use it, you just wouldn't be able to drive at the same time.

since combustion engines are so damm inefficient wouldn't it be nice if we cound get around the middle men and power the bullets directly with the fule.... wait a second, that souds familliar

and that 84 tonnes of force is only while it's firing, if you're only firing 200 rounds in a minute that's 280pounds. It sounds like a lot but you're sending out the same energy as a .50 browning with a higher velocity/smaller mass works out to less momentum. buffer systems just like on existing machine guns would probably work just fine. Not that I think going the higher speed route is the best idea here, the more you pump in the more you loose in the first 50 meters..

and the recoil force isn't against the motor, it's across the shaft, against it's bearings, doesn't really effect the motor except for increasing friction.

a dimpled surface helps with drag, not accuracy, and that only really applies for subsonic motion. Giving the boundry extra turbulence-> extra energy to remain attached to the surface behind the ball. supersonic flow has plenty of energy to reattach behind, the problem is in front, the air hitting up against the surface.
for minimum drag, subsonic you want a tear drop shape, supersonic you want a reverse tear drop shape.

yes supersonic bullets will make a shock wave, but you'll only hear that as the crack of bullets zipping past you. You won't hear the thump of it being launched in the distance. You might hear the engine on the vehicle running it.

Anyway this is, at best, a gigantic, inefficient, high powered shotgun.

51Cards
December 28, 2006, 11:24 PM
:scrutiny: looks like a Titleist II ...

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