| HN Mirror

It's very difficult to see a scenario where it makes sense to put a nuclear warhead on a hypersonic missile. The fact is, hypersonic missiles are dog slow compared to ICBMs. ICBMs though suffer from the tyranny of the rocket equation (most of the fuel they burn is used to push the rest of the fuel), so the mass of the warhead is a small fraction of the total mass of the rocket (for Trident 2 it's about 7%). The main problem is that ICBM's have to carry their own oxydizer, which is heavy. Cruise missiles get oxygen from the air, and this is a big deal. For a Tomahawk the warhead is 35% of the total mass of the missile. Now when you deliver a nuclear warhead (or a bunch), you don't care that much about the ratio warhead/total mass, since nuclear carries a lot of punch in a small package. And if you plan to start WW3, you might as well do it quick, no reason to use a (relatively) slow delivery vehicle, like a hypersonic one, when you can use an ICBM.

It's when you want to deliver conventional explosives that you care about how big your rocket is. It's one thing for the rocket to be 3 times as big as the warhead (Tomahawk) and another to be 15 times as big (Trident 2). The Tomahawk is really slow though, so the idea of the hypersonic is to be faster, at the cost of having a smaller delivery ratio. The fastest current cruise missile, the Russian-Indian Brahmos has a 12% ratio of warhead to total mass (if launched from an airplane, less if launched from the ground), and a speed of about Mach 3. What would be the ratio for a hypersonic weapon? It shouldn't be less than 7% (otherwise you keep it "simple" and use the Trident 2 design) and it's unlikely it will be higher than the 12% of the Mach3 Brahmos-A missile. It will be somewhere in between, and most likely not that disruptive after all.