RW mass-driver cannon

[Uncle Bob]

FROM EM gun on the brink of fruition for land and sea applications

UT-IAT has devised a common low-cost projectile concept for both naval surface-fire support and army non line-of-sight (NLOS) engagements using an EM gun launcher. It has a flight mass of 15 kg and contains either multiple kinetic-energy flechettes or a smaller number of sub penetrators made of tungsten. In its naval guise it has a muzzle energy of 64 MJ; a muzzle velocity of 2,500 m/s; a maximum range in excess of 500 km and an impact velocity of 1,600 m/s. From a more size-constrained land tactical platform it would be expected to have a muzzle energy of 20 MJ; a muzzle velocity of 1,400 m/s and an impact velocity of 700 m/s out to ranges in excess of 100 km

 

[RainOfSteel]

There seems to be something wrong here.

500 km and 100 km? Was that a typo? Shouldn't it have been 50 km and 10 km?

How could a 1.6 km/sec muzzle velocity go 100 km? How could only 2.5 km/sec (only a 56% increase) go 5 times further (a 500% increase)?

Remember, 500 km is 310.685596 miles. That's how much further than current artillery ranges (Navy or Army)?

 

[Uncle Bob]

MV 1400 m/s = 100 km
MV 2500 m/s = 500 km

These are low drag projectiles, and most of the trajectory will be in the ionosphere, not much drag. And the projectiles are KE, presumably shaped like a APFDS "arrow "

A 1950s Soviet 130 mm gun could get 27 km with a fat HE shell w/MV of 930 m/s.

 

[Chuck Anumia]

And these are the numbers being supplied to the Department of Defense.

 

[Anthony]

Assuming no drag, and ignoring curvature of the earth, which isn't quite fair for the 2.5 kps version (curvature of the earth should increase range by 10-15%), maximum range is approximately 100 km * MV^2, and maximum altitude will be 1/4 of maximum range, so that 2,500 m/s projectile reaches an altitude of more than 100 kilometers, and might be usable to shoot down low flying satellites, though you'd have to be amazingly lucky without a guided projectile.

Actually, stabilization might be a problem for the faster projectile; altitude is high enough that fins might not keep it aligned correctly, and if it descends into atmosphere at the wrong angle accuracy will be shot to heck.

 

[Fritz_Brown]

Here's a variation: DREAD Weapon System

And, a video.

It seems real enough. Possibility mentioned elsewhere: two counter-rotating disks (so there is no precession) firing simultaneously.

Edit: This sounds suspiciously like the bicycle weapon somebody mentioned elsewhere.... end edit

 

[Andrew Boulton]

Interesting idea, although it sounds too good to be true.

 

[tucker2]

Originally posted by Fritz88:
Here's a variation: DREAD Weapon System

And, a video.

It seems real enough. Possibility mentioned elsewhere: two counter-rotating disks (so there is no precession) firing simultaneously.

Edit: This sounds suspiciously like the bicycle weapon somebody mentioned elsewhere.... end edit

When I saw the illo I thought Jet-o-Disc gun on 'roids. I still hold out hope for a support version Jet-o-disc, I have the carbine already.

 

[Uncle Bob]

Problems with DREAD
1) Limited vellocity, IIRC 350 m/s
2) Spherical projectiles have lousy ballistics
3) There is no way to stabiluize the projectiles in flight.

So DREAD is a very high rste of fire but very inaccurate SMG, thst is three foot wide. No ammo cases, but you need to plug it in. I am not impressed.

 

[Andrew Boulton]

Unless my maths is wrong they quote up to 2400m/s.

 

[Uncle Bob]

Only 320 m/s demonstrated. The rest is smoke snd mirrors. I wexpect a lot of problems with shock wave formation once they try to push it supoersonic.

And assuming a .5 meter disk that is spinning at about 12K rpm, which is do-able with steel, just barely. 2400 m/s calls for 100K rpm, and 64 times the stress. I doubt carbon fiber could take that.

 

[Fritz_Brown]

Uncle Bob,
The pics of the ammo show a dimpled ball, akin to a golf ball. Should have very predictable ballistics.

Yeah, there is a lot of back and forth as to whether this thing is up to snuff, or not.

 

[mike wightman]

I don't quite understand how it can be made recoilless...

 

[Fritz_Brown]

I think the concept, Sigg, is that nothing is actually pushing back, because it is converting a circular motion to a linear motion - like a sling.

Some other folks don't think it will work the same way. And, someone mentioned some serious precessing if they really run this thing at high speed - just like holding that spinning bicycle wheel in physics....

 

[Andrew Boulton]

I looks too big to be man-portable, so I'm not sure if being recoilless really matters.

 

[Fritz_Brown]

For the projectile mass and muzzle velocity they were touting, one person was saying it would rock a HMMWV with its recoil.

 

[Straybow]

Well, skeptics said the 35mm GAU8 couldn't work on an airframe...

 

[Straybow]

A bicycle wheel has a substantial gyro effect because its mass is concentrated on the rim. A flat disk has very little gyro effect. A rotating shaft has virtually no gyro effect. It appears most of the mass is at the spindle, so it's gyroscopic characteristics will be somewhere between your drill press and the flat disk. Negligible.

If the current design is limited to subsonic it can still be an awesome anti-personnel weapon. It can still be very effective against soft vehicles, too.

 

[Uncle Bob]

Cannot defeat soft body armor. Gyroscopic effects will be serious because the weight at the rim will be more than the bicycle tire, plus all the mass at lesser radii. All moving about thirty times faster than Lance Armstrong's tires.

320 m/s won't penetrate soft body armor. Maybe not even 1960s flak jackets. And the dimpled balls are better than smooth, but not good. A foster-style shotgun slug would be more accurate.