Sunday, December 01, 2013

Hypersonics are not the New Stealth

Last week, Aviation Week published an opinion piece by Bill Sweetman which puts forth the argument hypersonics could be the next great advantage for the US and other countries taking the place of stealth technologies.  He lays out his arguments both in terms of physics and from the historical record.  I would like to tackle these two aspects of his argument and point out why he is wrong.

Before I begin, while I am going to argue - sort of - on the side of McNamara, I want to restate my contempt for the man.  McNamara did more damage to the US national security than almost any spy has ever done.  His legacy is the bloated, almost corrupt procurement processes which reward which cause incredible cost overruns and late delivery of weapons the US military needs. 

Furthermore, I want to state wholeheartedly I am in support of developing hypersonic technologies.  I strongly believe they are not only worth the trouble, but will bring new capabilities which we lack: prompt response and being able to overwhelm air defenses through extremely low response times are just two.  Having mucked around in material science, this is also an area I think will great benefit venturing into the hypersonic realm.   In addition, a hypersonic bomber when paired with stealth bombers makes the enemy have to prepare in two radically different ways: but this may not work and I'll explain later.

History First:

Sweetman lays out a good story about the history of the B-70 bomber, A-12, the SR-71 and the YF-12.  He states McNamara cancelled the B-70 and put the breaks on the development of the A-12 variants was because there was a strong belief the Soviets would develop missiles which would be able to take down any aircraft no matter what its altitude and speed.  McNamara then 'forced' the USAF to start designing around the idea of 'nap of the earth' flying, which Sweetman disparages.  Furthermore, he decalres McNamara was wrong: the S-200 and MiG-25 could not catch the SR-71 and no missile or aircraft was developed which could.

First off, he got something rather wrong.  Eisenhower began canning the B-70 program prior to Kennedy's election: Eisenhower restricted the development of the B-70 to a single plane!  In fact, Kennedy was in favour of the B-70 program until after he was elected and was given access to all the information: then he cancelled it.  Two very different administrations took the same view.  McNamara for all his sins, was not the villain here....despite Sweetman's stance.

Secondly, Sweetman states that the only way an SR-71 or B-70 could be taken down by a SAM (or AAW missile carried by a Mig-25) was if it was the 'instant sunshine' kind.  Guess what?  A lot of the SAMs, specifically the S-200 which he disparages, were armed with nuclear warheads.  It may seem insane to those of us which live in the early 21st century, but in the 1960s both sides deployed SAMs and AAMs with nuclear warheads.  

Third, it is true the SR-71 could not be caught without the use of a nuke.  And it is true Soviets never developed a SAM or aircraft which could catch the SR-71.  There was a really good reason: it was pointless.  Oh, not because it couldn't be done, but rather the SR-71 didn't provide anything which the spy satellites were not developing already.  Overflight was established for spy sats.  What made the SR-71 any scarier?  Nothing did.  It was an annoyance, nothing more.  One which could be herded somewhat with the MiG-25s, and later with MiG-31s, but really was not something which the Soviets needed to fear.  If its damned expensive, doesn't really help protect, why bother?  The Soviets saw it the same way and didn't.

Physics & the Future Next:

Even so, Sweetman goes on to state given no one has a way to catch a Mach 6 plane we ought to go and build either spy planes based on Lockheed's SR-72 concept or even bombers for the next generation bomber effort.

First off, there are missiles which can fly even faster which already exist.  Oh, to be sure, they are not intended for hitting aircraft.  After all, there are no aircraft which fly at Mach 6.  yet.  However, THAAD flies at Mach 8.  The PAC-3 Patriot Missile, which has a short range, flies at Mach 5.  The S-400 SAM flies at Mach 5.  As soon as hypersonic bomber appears, you bet one of these or some other missile will appear which will be able to intercept it.  The longest time frame would be ten years afterwards.  This is not the 1960s: material science as marched on, as has electronics and rocket fuel.

Secondly, bluntly, c is much faster than Mach 6.  "Huh?"  you say.  What's c?  For almost any physics geek, that ought to be obvious: c is the speed of light.  Lasers are coming out of the science fiction realm and onto the battlefield.  HELLADS, RELI, EXCALIBUR and the US Navy's FEL will all be fielded in the same time frame, if not sooner.  To go from horizon to horizon at Mach 6 takes over 45 seconds.  If a laser cannot bag something in 45 seconds, it won't be deployed.  In fact, a laser shoot down takes far less time than 45 seconds.  HELLADS, fwiw, is intended to be placed on aircraft, like the F-35A. While all of the above are American programs, one almost assuredly bet the Chinese are working on laser weapons as well and while Mach 6 aircraft are intended to handle high heat loads, lasers especially pulsed lasers, will induce higher loads, with greater shock than those materials will be able to handle.  With weapon grade lasers (100kj+), if you can see it, it dies.  Simple as that.  If you fly high, you're toast because we can see you for longer.  And to fly fast, you must fly high.

Why Build it When You Already Have the Capability:

You have to wonder what I mean, right?  No, I have no delusions of a Project Aurora.  That has never panned out.  The replacement for the SR-71 was the spy sat.  And for dealing with the need for a easily retaskable spy sat, we have the X-37B.  It works just fine.  And has flown several times.  It just needs a tweak to the system which gets it into space.  Gosh, DARPA's XS-1 program seems to fit just that.  For recon, there's no need for a SR-72.

What Use ARE Hypersonics Then?

Missiles, bluntly.  If you can fire a missile which can arrive faster than the decision time of a ship's commander from a platform that commander cannot see, then you have the advantage.  A stealthy aircraft which can pop off mach 5+ missiles can do far more damage than an aircraft which will have the IR signature of a meteor and fly way up high will.

Wrap up

Strawmen are bad to use for arguing.  The past does not reflect what Sweetman writes in his article.  The present and near future do not either.  Sweetman loves speed.  He has for a long, long time.  Its merely the future does not fit what he describes or wants.  Its far better to be not seen at all than zip along fast.  Once you are found, in the future, you die.  And there's no way to hide the Mach 6 IR signature in the era of IRST.

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