Thursday, July 05, 2018

My Hypersonic Skepticism

I am going to post about something that I don't usually post about because I prefer to steer clear of sensitive IP matters.

But there is a lot of back and forth going on about the hypersonic flight issue and as one of those "skeptical technologists" (described in this article) , I feel like my point of view is under attack from a vicious hype cycle that is corrosive to the people who actually work in this field. I am deeply disturbed by the manner in which Trump and his enablers weaponize stupidity to their own political advantage.

Briefly - I believe the whole idea of a weapon based on maneuverability at hypersonic speeds is bullshit. I think claims of having constructed such devices are hype - much like the "Star Wars" program that Reagan and other vested interests (Teller!) touted about.

A while ago, I sat down with a black piece of paper and asked my how I would design a hypersonic vehicle and I went through that thought exercise I came up with the following conclusions.

1) The vehicle would only be viable if I didn't have to carry the oxygen. (see the part in the article about "air breathing" & "boost glide").

2) Endurance and maneuver would critically depend on the ability to achieve a very high combustion efficiency (see that part of the article about "inlets, ducts & holes") and intelligently managing extremely high levels of aerothermodynamic heating.

3) Managing aerothermodynamic heating effects in these platforms would require a new class of materials with unique properties like perspiration or extraordinarily high levels of structured heat conduction.

4) The costs associated with the engineering of such advanced "smart" materials would make this vehicle unsuitable for military applications which require cheap disposable platforms.

Based on my own analysis (which only focused on the physics of materials and the coupled nature of the heat transport and Navier-Stokes equations) - I felt that outside of a niche application in a highly specialized sub-field of weapons technology the hypersonic vehicle would be unlikely to have the kind of mass applications that were projected by the technology's proponents.

After the technical study, I attempted to trawl thru what Chinese and Russian literature was on the web and I could not make head or tail of their claims. I sensed that they were keen to show that they possessed a technology that could defeat the US lead in missile defense platforms. The Russians with their aging nuclear missiles (which never had great guidance systems to begin with) and the Chinese with their limited arsenal were very eager to prove to their own Nat Sec community that US advances in Ballistic Missile Defense were not really a big deal.

The Russian and Chinese information operations, however appeared to have had an unusual by product. As the US was keeping most of its own hypersonic research a closely guarded secret, it could not respond publicly to Russian and Chinese claims. And with that vacuum came a politicized hype cycle. The Chicken-hawks in the US Nat Sec community charged ahead into claims that their political adversaries were holding the US back.

To my mind - the Russian and Chinese information operations may also have intended to force the US to come out with more information about its own advances in hypersonic technology and given how much Trump and the GOP bend over backwards to accomodate Chinese and Russian interests, I  am worried what new stupid stunt is in the works right now. Who knows what will be shared in the private meeting between Trump and Putin at Helsinki!

As far as I am concerned, the only thing that the Russians and Chinese need to know is publicly available outcome of BMD tests. They can take averages as easily as I can and work out how much it has altered the OAR of their platforms.

There is no need to push this issue into a state where no technological resolution is meaningful. A roadmap can be made as long as it not filled with nonsensical ideas. And by that I mean this kind of stuff (see the linked article).

 “if you let [hypersonic weapons] get into terminal phase, where we’ve observed that they can pull many G’s, then that becomes a hard target,” Griffin allowed. “If you allow an attacking vehicle to get close enough to begin its terminal dive …and [that] might be from 100,000 feet … you’re probably dead meat because that’s a very hard intercept problem... at that point.”

This problem is not unique to a hypersonic cruise missile - this is equally applicable to a ballistic missile in the terminal phase too (which incidentally is also hypersonic). So why pass it off as something unique to the hypersonic cruise weapons issue.


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