US Navy DDG 1000 Zumwalt Class

lucretius said:

Word on the street is that the railgun engineers are having a very tough time designing a projectile which can contain explosives and survive the firing process.

At the moment it is "line of sight only", solid projectiles.

Click to expand...

Designing explosive warheads for it has never been the emphasis.

It is using its high speed and the associated forces to destroy the target.

Designing sensors to survive firing is something that can...and I predict right now...will be done.

That's different than designing an explosive warhead.

Having said that, I find it difficult to believe that they would have such difficulty because the old 16" guns had a heck of a muzzle velocity...and they achieved that by setting off a massive explosive charge behind the warhead that itself was filled with HE. And they did just fine.

There is no "explosion" that powers the rail gun projectile.

I believe the problem is in the intense heat from the friction/speed/muzzle velocity

With a railgun you are looking at 8,270 feet per second compared with 2,500 feet per second on the old 16" guns.

The railgun projectile relies on kinetic energy to destroy it's target, so any attempt to change it's course mid-route will significantly bleed off the available energy and subsequent destructive power.

I believe the railgun is a useful tool (if you have the spare power to run it), but there are large gaps in it's capability that will have to be filled by other solutions.

lucretius said:

Word on the street is that the railgun engineers are having a very tough time designing a projectile which can contain explosives and survive the firing process.

At the moment it is "line of sight only", solid projectiles.

Click to expand...

If we're looking at a Mach 7+ muzzle velocity, finding a right warhead filling might indeed be a challenge. Most explosives have an acceleration threshold before detonation, and that is one of the primary reasons why plastic explosives are rarely, if ever, used in shells.

Although, like Mr. Jeff Head said, these projectiles would mostly use their pure kinetic energy to impart much of their destructive potential.

I suppose the advantage of the rail-gun's "digital propellant", is that one may "dial down" the speed to a more acceptable level.

Of course than you have the issue that you have just negated the primary advantage of the rail-gun... it's range.

... and of course if you are storing explosive projectiles, you also remove the advantage of solid ammunition

lucretius said:

I suppose the advantage of the rail-gun's "digital propellant", is that one may "dial down" the speed to a more acceptable level.

Of course than you have the issue that you have just negated the primary advantage of the rail-gun... it's range.

... and of course if you are storing explosive projectiles, you also remove the advantage of solid ammunition

Click to expand...

I don't see why there would be a need to make drastic changes to its muzzle velocity, other than the explosive issue, if you can simply alter your gun's elevation and traverse (which will result in significantly higher gun accuracy than the former method).

At Mach 7, the projectile's heat from air friction would be quite significant as well, thus augmenting its hitting power (read the novel "Stony Man: Sky Hammer").

Would the projectile still be travelling at mach 7 though as you increased the elevation?

By the end of it's arc it will be travelling a fair bit slower IMO, though mathematics is not my forte.

lucretius said:

Would the projectile still be travelling at mach 7 though as you increased the elevation?

By the end of it's arc it will be travelling a fair bit slower IMO, though mathematics is not my forte.

Click to expand...

The projectile will change its velocity during its flight due to drag and gravity, of course, but its speed would still suffice to cause it to heat up considerably (you wouldn't expect it to drop dramatically in speed).

"Stony Man: Sky Hammer", thanks for the recommendation, I will be sure to check it out

lucretius said:

"Stony Man: Sky Hammer", thanks for the recommendation, I will be sure to check it out

Click to expand...

To be honest, the entire series was a bit cheesy and clichéd, but it's an interesting read (however ridiculous) from a purely technical perspective.

Jeff Head said:

Yes, and your fire control would take all of that into account...and today's fire control would be smart enough to factor in recent maneuvering and program in predictability algorithms to be able to much better indicate where it would be 300m later.

Click to expand...

thanks Jeff, later in the day I did some additional thinking and it seems to me they'd need to be shooting at some pretty steep angle to hit the target at 60 km ... this would significantly increase the time of flight ... for rail-guns, there are no Admiralty Tables I could use as in https://www.sinodefenceforum.com/world-war-ii-historical-thread.t6728/page-21#post-267910 ... but yes, if they indeed were able to fire ten times during one minute (which I still can't imagine https://www.sinodefenceforum.com/us-navy-ddg-1000-zumwalt-class.t5546/page-30#post-336507), it should be relatively easy to bracket the target!

Jeff Head said:

They factor all of that into the design. They can make them not only small enough...but tough enough...to handle the forces resulting from the rapid acceleration of firing.

Click to expand...

I expected an optimistic answer I wonder about two things though:

• the cost of the guided rail-gun shell (the unguided should cost $25k -- that's how I understood what the Project Manager said https://www.sinodefenceforum.com/us-navy-ddg-1000-zumwalt-class.t5546/page-30#post-336507)
• the Vulcano ammunition glides (at Mach one and a half maybe?), has canards for the terminal stage of the attack -- I have no idea what to use at Mach 7 "instead" ... or would "special fins and autopilot make it"?? ... or ... please tell me