One suspects the shape is derived from a few factors. The rear C shaped part would appear to be designed to contact the rails (it is flat on the outsides) and conduct the driving current through the C. The cylinder to the front of the projectile seems to be there to hold the square top - which, I suspect, is an insulator and is designed to sit within the rails and stabilise the projectile whilst it is being accelerated.
They claim the projectile is hypersonic. Aerodynamics get weird at those speeds. The idea that you need a pointy projectile isn’t really the case. No matter what, eventually you have to shift the amount of air covered by your cross section, and whether the nose is pointy of not does not affect this. Indeed a pointy shape simply has more surface area that is seen by the hypersonic flow, and you get worse frictional losses. A blunt nose is actually better. Famously, the Space Shuttle has a blunt nose for just this reason.
Yeah, and must be able to withstand “exo-atmospheric flight”? I think they are preparing for a railgun with a range outside of 200 miles if the projectile needs to spend some time in space. Unless I’m reading that completely wrong
The g-loading in the cited spec looks fearsome, but probably isn’t that innovative, considering the Army has had gun-launched electronics for some time, like the Copperhead laser guided 105mm round. This .pdf is a brief examination of some of the issues in designing electronics for that environment regime. Further, this paper from the Ballistics 2011 26th annual international symposium, goes into further criteria for selecting electronics potting materials for gun launch.
As a layperson, so completely speaking ex rectum, what I see being the real pain to deal with, will be shielding the electronics from the high, drastically changing, magnetic field environment. I would think that properly choosing the potting material would suffice for the temperature and radiation hardening specs. I wonder if they’ll use photonics or some other means of light pulses, instead of traditional solid-state electronics?
As far as the height of the trajectory, it’ll make their energy requirements a lot easier if the projectile goes through as little of the lower parts of the atmosphere at possible. Even the big guns on the old battleships, with their comparatively paltry ranges of 20-25 miles, had a maximum trajectory height of 3 miles plus. See this discussion of trajectory heights here. I know the range tables for the 16 inchers are floating around the internet somewhere.
Is this likely going to be a US Navy only weapon? One of the prototype are being designed and developed by BAe Systems, using their own money. Are BAe going to be allowed to sell this on to allied nations?
Yes, many have said the projectile is conductive but it’s not. A big chunk of conductive metal tends to get welded to the rails. A conductive armature is placed behind it which the electricity vaporizes into a plasma. In many designs, the armature is little more than aluminum foil, but it’s called a “plasma armature railgun” because vaporizing the foil into plasma is one of the first steps and the plasma is the goal. I think I read that plasma was pumped into the Navy’s gun. I don’t know if that’s inaccurate reporting or what.
Anything developed here in the US would be subject to the International Trafficking in Arms regulations, and government licenses would be required to export the articles themselves or technical data about them.
