I wonder if the July test is supposed to be a secret, we'll have to tune into this magazine after the tests to find out what the results are.

The picture is from a DoD publication and the stats are for real IIRC. So what, it's the details that matter, we have seen actual photos of rail guns and other more secrit weapons before. It just whets their appitite and shows them how far behind they really are!

Back in the late 60's, early 70's, when development of the Safeguard ABM system was in swing, the US was testing with the Sprint ABM, a 27-foot long missile with phenomenal performance: a unique booster allowed 100g launches topping out at a velocity (downrange) of 6 miles per second (yes, miles.) The missile, armed with a t-nuke warhead, was coated with a phenolic substance that allowed the weapon to cross such speeds without cooking itself apart during its brief flight. Apparently, they were still able to get command signals through the ionization that surrounded the missile's body. During the Reagen-era Star Wars programs, the National Aerospace Plane was estimated to reach speeds approaching Mach 25 (at high altitudes and re-entries.) Definitely, the military aspect of a transcontinental bomber that could cross the world in barely half a day were enticing: it was discovered in wind tunnels that, at such velocities, an ionized layer of particles, which actually helped insulate the platform from the atmosphere, was built up around it (similar to the shuttle's re-entry characteristics.) It was anticipated that this ionic layer would even disrupt a directed energy weapon's effects, and as no air defense system was capable of computing such interceptions, the strategic and tactical benefits of a military version became quite obvious. But, the technology of the materials just did not exist then to make such a craft feasible. As far as the launch stresses on railgun ammunition: we certainly can fabricate guidance systems capable of withstanding the hi-G launches, and build the rounds out of materials capable of withstanding the hot atmospheric drag (at least for the several dozen seconds' to couple of minutes' flight time.) The question I would raise on the "sacrificial" coating of such a projectile: how can it be effectively controlled enough that it will evenly burn off so as not to drastically affect the round's ballistics and flight profile? If a chunk were to suddenly flake off at the wrong spot (considering the high velocities involved, >1 mile/sec), the shell could become unbalanced enough to induce a wobble, which could cause the shell to eventually tumble uncontrollably, and disintegrating in flight. A tank sabot only going a mile or so is one thing. But firing a shell at such velocities over great ranges would have issues with this. I think this would be a bigger issue than accurate guidance over long ranges.

If its goin to be tested then its highly likely it will be tested at Yuma Proving Ground, Im pretty sure they have tested EM Rail guns before, but nothing of this scale!!!

I think the burn off coating on a projectile would be a sprayed application that would burn off right about the time the projectile leaves the muzzle, the quantity of material applied should be easily controllable by robots. It is my guess (and a less than educated one at that) that the hottest part of the projectile's trip would be inside the rail gun, so that is the only place the coating is important. There are always mistakes in manufacturing, so there may be times that there is too much or to little applicant put on. Too much applicant and there may be increased and uneven drag on the bullet, too little and the bullet might start to melt or explode inside of the gun. The latter sounds much worse.

As far as asymmetrical loss of coating, since the shell is guided as long as it's not too severe, the guidance system should be able to compensate. This is going to be one delicate guidance system at these speeds ;) Should be no problem with stress on the guidance system, as it's solid state, and as long as the chips are firmly supported it should be OK. I suspect they will encapsulate the leads inside the chip to prevent flexing.

I expect the hottest part of the trip will be after it hits top speed. At top speed, the heat flux is maximum. To find the hottest part of the trip requires an integration, but it should come a some distance later.