I found this sort video really interesting, this prototype weapon shoots a projectile over 110 miles. Does anyone know how to estimate what sort of muzzle velocity this would need to have to accomplish this?

Sorry if I didn't post this link the right way, I'm not sure how to attach a video.

Doug
New Military Prototype

10.64 MegaJoules .... Mach 5 are figures mentioned in one of the other movies offered once you see this one. A lady says they can fire the projectile into space, and put steel on target at mach 5. She mentions 200 miles as well.

Quite a tool there. Let's see .... I have some batteries ... some copper wire .... hummmmm

Gary

The part I don't get, Gary, is that isn't Mach 5 around 4000 fps or so? And don't some rifles come close to that, and yet they have a maximum range of very few miles. I know the energy is much greater in this weapon due to the huge slug, but why does it fly so much farther than a rifle with say 3000+ fps velocity. Is it because the much heavier projectile goes further? I don't think the slug has a propulsion unit of some sort, does it? Sorry, having a hard time understanding this one.

Hi Doug,

Speed of sound is dependant upon the elevation where you are. I think the avg. we think of is around 1,100 - 1,150 fps IIRC. So - Mach 5 using that figure would be 5,750 fps. I don't know the size of that projectile - but it looked healthy.

The lady expert on the NAVY film seemed to be speaking of a ballistic trajectory - with final strike @ Mach 5.

I suspect Jerry may know more about this than he can tell. So - we might get some clarification later in the day.

Gary

Hey - wait until they spray metallic paint on pumpkins and start using rail guns at Pumpkin Chunkin!@




WORLD RECORD Navy RAILGUN 33-megajoule Mach 7 firing 2010 another film listed there. And, the projectiles on the bench looked like some could be 3-4 feet long. Looked like some of my classified stuff. .....



Edited 1 time(s). Last edit at 12/17/2010 06:13PM by barnespneumatic.

I have no idea what the initial velocity of the rail gun projectile is. It is certainly interesting technology though. I expect that in a few years they will have figured out how to get a barrel to last more than one shot.

Aircraft carriers are also going to have rail guns, they will replace the current steam catapults for launching aircraft. Fortunately these systems don't have to generate hyper-velocity!

Thanks Jerry,
Maybe you can explain to me the part I'm not understanding, which is how can this weapon have such a long range (110-200 miles). Is the projectile somehow self-propelled? If not, is the range due the the weight of the projectile? I just can't figure out why it would have such range compared to rifles with velocities near 4,000 fps, unless there is some sort of law of physics that says a heavier projectile will fly farther than a lighter one. Sorry, just not wrapping my brain around this one.
doug

Hi Doug,

I'm no expert on this topic but here are my two cents:

It has been proven again and again that the heavier the projectile, the longer that it will keep it's energy and the further that it will reach.

There's also the ballistic coeficient. It's not only weight that's needed, we need to add the correct ballistic coefficient in order for this projectile to reach those distances and still keeping the speed.

Julio



Edited 1 time(s). Last edit at 12/19/2010 09:02PM by Julio.

Consider that, in WWI ... the Germans had a different kind of rail gun (huge cannon mounted upon railroad cars ... and HUGE cannon doesn't start to say it) ... anyway ... they shelled Paris from 79 miles away. The slug weighed half a ton or more ... and was in the air so long, that they had to account for the earth's rotation during it's time aloft to aim.

Keep in mind ... what is the horizon from a ship ... 7 miles at sea? Something like that. Therefore; the only way to shoot 200 miles ... is to do a heck of a loft. As the one lady on the flims said .... ballistic.

Gary

C'mon . . . the Germans were just copying good ole American ingenuity, and scaling things up a bit. I give you . . . "The Dictator."

[www.old-picture.com]

This 13" railroad flatcar-mounted mortar was used by Grant to shell the Confederate lines at Petersburg 1864-1865, from a distance of over a mile at a fixed 45 degree angle.

-- Jim



Edited 1 time(s). Last edit at 01/04/2011 11:01PM by admin.

Ok, I finally get it. Thanks everyone.

Don't forget there are GPS devices imbedded in the new crop of artillery projectiles. You solve the firing problem for distance, the
GPS receiver on board flies the projectile to the target.

Don't forget the the artillery guys have been doing this stuff for a LONG time, they've got some tricks up their sleeve. One of the biggest factors is that projectiles of this size have a BC that's off the charts compared to little, bitty .30 rifle rounds. If you look up the BC for a 50 caliber round versus one for an identically-shaped (but smaller) projectile for a 30 caliber bullet, you'll see that size DOES matter. It's common for a .50 projo to sport a BC in excess of 1.0 but you're hard pressed to hit .50 in the .30 range. Another trick that the big-gun guys have is to include either rocket assist or base-bleed into their designs. Rocket assist is pretty clear, but base-bleed is pretty specific to artillery terminology. Basically, it sort of a low-power rocket in the base of the shell that puts out just enough gas to fill up the vacuum or low-pressure zone that impinges on the base of the projectile in flight, thereby reducing it's drag dramatically. When you consider that the average artillery shell is dragging along a low pressure zone behind it thats between five to eight inches in diameter, it makes sense that filling in that void will make the shell fly further with the same muzzle velocity. In fact, when the manufacturers start tossing around maximum ranges for their artillery systems at trade shows and in journals, the fine print almost always mentions that it's achieved with a base-bleed round, even though the actual cannon-cockers usually aren't particulary thrilled with them. As with all systems, every advantage incurrs a trade-off, you can't get something for nothing. Including rocket assist or base bleed means that you get less room for high-explosives in the shell, so you get less "target effect" than with a regular round, and they're generally less accurate as well. The more complicated you get, the more room for error you introduce even if you hold your quality control to high levels. Seeing as the end result is to blow the things up in fairly large numbers it's hard to justify spending top-dollar. And yes, these days even artillery shells can have GPS. It doesn't make them fly any further, but it sure can make them more accurate out there at the far end of their effective range. Of course, that's provided that the bad guys don't have GPS jammers, but that's a whole 'nother story.

HI Rotor,

Missed this post earlier.

So ..... ..... Rotor ..... you either read .... ALOT .... or you've been holding out on us. Are you sure there aren't some spy types looking for you .... hahahah.

Interesting stuff. You win. ;?)

Gary

I blame it on my uncle... Specifically, Uncle Sam.

As an attack helicopter pilot, my formative years were spent blowing thing up for a living. In the absence of a shooting war with the Soviet Union, we spent a lot of time considering the finer points of interior and exterior ballistics. Not to an obsessive-compulsive degree like the redlegs (artillery pukes) of course, but hey, you can't fly ALL the time.

spectacuar stuff , amazing what you can do with a huge budget , all the time you fancy and as many machines and toys you need to be able to play ,,, but to get paid for it as well , hats off to those guys.

"I'm just saying responce ....."