Hypersonic weapons on the verge of reality for U.S. military

The US Air Force will be flying operational prototypes of hypersonic weapons by 2020. At least that’s according to Major General Thomas Masiello, commander of the Air Force Research Laboratory, who spoke last Friday at the Air Force Association Air Warfare Symposium in Orlando, Florida.

This may mean that hypersonics are just about through what engineers and program managers call the “Valley of Death,” which is a sort of Catch-22 where a lot of good ideas languish and die.

Taking any idea from the drawing board to operational deployment is expensive.

There’s one phase where that development starts getting really expensive, but it’s before anyone has enough confidence in the new idea that they’re will to lay out enough money to make that technology usable in practical terms.

Once a program makes it through the Valley of Death, it’s pretty much a given that it’ll go from being an exotic idea to an actual thing in the US arsenal.

That 2020 target is ambitious, and quite simply because going hypersonic is not easy at all. Hypersonic speeds begin at, roughly, Mach 5 — one mile per second or five times faster than the speed of sound.

That’s a sort of generic cutoff at the low end, while the top end runs all the way up to Mach 25, (depending on who you ask). However, the actual, not-completely-arbitrary, laws-of-physics cutoff is a bit harder to precisely define.

An object traveling at hypersonic speeds is going so fast that it generates enough heat, shock, and pressure to alter the basic chemistry (and therefore aerodynamic properties) of the air it’s plowing through. It just so happens that this kind of disruption is a pretty major factor by the time a vehicle has hit Mach 5. But the transition isn’t sharp. As you go faster, the whole engineering problem gets increasingly screwed up in new and extremely difficult ways.

The big problem is that computer modeling of hypersonics is really hard when the individual elements start becoming recursive and, therefore, computationally very demanding. Beyond that, the vehicle itself is putting tons of energy into the system; thermal loading becomes an enormous pain in and of its own right. And on top of that, trying to keep a jet engine lit at 3,000 miles per hour is a nightmare, too. Blah blah blah.

Or something. The basic deal is that hypersonic stuff is well into the range of super-duper hard even for the bright bulbs at NASA and DARPA, the Defense Advanced Research Projects Agency.

While it’s been a huge pain to do hypersonic stuff, it’s also been something that aircraft designers have wanted pretty bad. Ever since people started making combat aircraft, making them faster has been a pretty surefire way to guarantee a better warplane. But in the 1960s, designers started hitting a wall up around Mach 3 or 4, after which it starts becoming very difficult and expensive to make the plane go faster.

By the 1970s, designers quit pushing speed limits, and focused on how to camouflage aircraft instead. They did this first by flying super close to the ground so enemy radar had a hard time picking planes out against the terrain. Later, this approach was overtaken by stealth technology that made it hard for enemy radars to pick out the plane against much of anything at all.

In a way, stealth and hypersonics represent two completely opposite solutions to not getting shot down. Stealth is all about being so ninja-like that nobody can see you. On the other hand, vehicles at supersonic speeds and above generate a huge amount of heat, which makes them easy to spot. But they are cruising along so fast that it’s tough to intercept them and shoot them down.

But there’s more. Hypersonic aircraft can get anywhere pretty quick, and that’s important if you want to react quickly to something that’s happening far away from you — which is a big deal if you are the United States.