Friday, January 22, 2021

Are Hypersonic Weapons Actually An Aerodynamic "Mirage" ?

 


When I first learned two years ago that the Russians were planning to develop "hypersonic" missiles to deliver nuclear warheads in half the time or less that it now takes, I sensed a scam.  Something along the lines of what the U.S. under Ronnie Raygun pulled in the 80s with the "Star Wars" anti-missile bunkum.  Well, one aspect of Reagan's nonsense did work: it damned near bankrupted the Russians to try to keep pace.

We know the hype over what military experts call hypersonic warheads  has been ongoing for just over a year now.  It's centered on these weapons being the latest big thing in intercontinental warfare. We're expected to believe these things can deliver nuclear warheads while zipping along at up to five miles a second while zigzagging through the atmosphere to outwit early-warning satellites and some interceptors. These superfast weapons, experts say, lend themselves to making surprise attacks.

Once again letting his ignorance drive his curiosity Dotard Bonespurs once bragged about his “super-dupers,” even referring to the planned weapon as “hydrosonic,” a brand of electric toothbrush.  That reminded me of the time Ronnie Raygun once asked if cruise missiles with nuclear warheads could be "recalled".  

Fortunately, before President Biden and the U.S plows several trillion into these weapons, independent experts who've studied the technical performance of the planned weapon now conclude that its advertised features are "more illusory than real". Their analysis is to be published this week in Science & Global Security.

Richard L. Garwin, a physicist and longtime adviser to the federal government, called the paper “very good and important.” He added that he had provided his own similar criticisms of hypersonic warheads to defense officials.

James M. Acton, a nuclear analyst at the Carnegie Endowment for International Peace, called the paper “a serious, credible and important piece of work.

Dr. Wright is affiliated with M.I.T.’s Laboratory for Nuclear Security and Policy and did the analysis with Cameron L. Tracy, a materials scientist at the Union of Concerned Scientists, a private group based in Cambridge, Massachusetts  (to which I also belong) and that often backs arms control.

By definition, hypersonic vehicles fly at more than five times the speed of sound or  330 m/s x 5 =  1650 m/s  — up to dozens of times faster than jetliners. The warheads rise into space atop a traditional long-range missile but then descend quickly into the atmosphere to bank, careen and otherwise maneuver. They’re basically stubby gliders. The curved upper surfaces of their wedge-shaped bodies give them some of the lifting power of an airplane wing.

Dr. Wright and Dr. Tracy based their analysis on the Hypersonic Technology Vehicle 2 — an experimental warhead developed by the Air Force and Darpa. Their findings, they say, also apply to other American prototypes, as well as devices being developed by China, Russia and other countries.

In order to model the most plausible flight paths  the computer simulations drew on the physics of moving bodies and public disclosures about the Hypersonic Technology Vehicle 2 . The team then  zeroed in on signature phases of hypersonic flight — i.e. when the vehicle zooms through the atmosphere and then plunges to hit a target.

The two experts say their computer modeling fills in public gaps on the weapon’s overall performance as well as its potential interactions with existing military systems for detecting and defeating weapons launched from distant sites.

In their paper, they depicted the weapon as essentially failing to outwit early-warning satellites and interceptors. For instance, current generations of space-based sensors, they report, will be able to track the weapon’s fiery twists and turns during most of its flight through the atmosphere.

Surprisingly, given the weapon’s speedy hype, they also asserted their analysis showed it would fly intercontinental distances more slowly than ballistic missiles and warheads fired on low flight paths known as depressed trajectories. In war, such tactics are seen as a good way for attackers to evade interceptors and lessen warning time.

Drs. Wright and Tracy conclude that this hypersonic weapon is, at best, “evolutionary — not revolutionary.”  Hmmm....how about science fiction, or fantasy?

In their paper, the authors contrasted their findings with military claims. For instance, they quote the 2019 Senate testimony of Gen. John E. Hyten, the Air Force officer then in charge of U.S. Strategic Command, which controls the nation’s nuclear missiles. According to General Hyten,  the time for a hypersonic warhead to complete an attack: “could be half that of a standard missile. It could be even less,

The clashes between public views of hypersonic warheads and their actual abilities, the two experts conclude, arise from overstated official claims meant “to justify the expenditure necessary” for their development and deployment.

The team’s analysis, he noted, focuses on an underlying issue of physics that he said casts doubt on the new class of weapons in general.

It’s what aeronautical engineers call the lift-to-drag ratio. The esoteric term is a measure of lifting power versus drag. Lift pushes a speeding aerodynamic body up and atmospheric drag tries to counteract the forward motion, at worst prompting a stall.  The diagram below shows the basic relationship:

 Wright's team’s analysis of the hypersonic vehicle used a lift-to-drag ratio of 2.6. In contrast, jetliners (and some birds)  have a ratio approximately eight times higher. In other words, the warheads at best are rather unimpressive fliers.

The limited power of the curved, blistering hot surfaces to generate a substantial lifting force without also producing lots of drag undermines claims that the weapon can fly long distances on complex trajectories, he said. According to Prof. Wright:

Unless they’ve found some magical way to keep these systems up,  they’re going to have problems.”

My suggestion to President Biden would be to scrap this turkey now, before any more money is plowed into it.  White elephant, anyone?


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