ACHIEVING HYPERSONIC GREATNESS
[
Dr. Ed Pope
](https://www.linkedin.com/in/dr-ed-pope-161a322b/)
Consultant and Subject Matter Expert
1 article Following
December 27, 2023
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“Go big or go home” is an aphorism familiar to the fitness world. It’s also the philosophy of visionary entrepreneurs like Elon Musk and Steve Jobs. You can’t do great things by pursuing modest goals. In the words of Emerson, “Greatness appeals to the future.” When it comes to hypersonic missiles, is the US aiming to achieve greatness?
To achieve total dominance, the US can’t afford to be an “also ran” in the hypersonic missile race, lagging behind China and Russia. In their exceptionally well-written and researched paper in Science and Global Security, David Wright and Cameron Tracy do a tremendous job of laying out the challenges in current hypersonics [1]. With no less than 95 careful and detailed references, their paper “Hypersonic Weapons: Vulnerability to Missile Defenses and Comparison to MaRVs” is well worth reading.
There are three principal types of hypersonic missile systems. These are hypersonic cruise missiles (HCMs), boost glide vehicles (BGVs), and maneuverable reentry vehicles (MaRVs). Each has unique advantages and challenges. A hypersonic cruise missile is akin to a Tomahawk cruise missile on steroids. HCMs are extremely maneuverable and versatile, much more so than BGVs and MaRVs. To avoid interception, however, the current airbreathing hypersonic cruise missiles (HCMs) are too slow.
In GE Aerospace’s recent dramatic announcement, a new “chimeric” propulsion system for air-breathing hypersonic missiles has been developed and tested [2, 3]. It integrates both traditional turbine engines with rotational detonation engines (RDEs). As truly revolutionary as this development is, GEs publicly stated hypersonic cruise missile (HCM) propulsion goal is to “exceed MACH 5, or >4,000 MPH” [3]. That’s still slow enough to be vulnerable to interception [1]. Claims of Mach 10 in some overly exuberant media outlets are unsupported. Mach 10 remains an aspirational goal, at best.
The top speed of HCMs is primarily propulsion system limited. For more speed, what’s needed are improved engine designs. They’ll also need highly energetic non-hydrocarbon fuels with vastly elevated combustion temperatures (e.g. hydrogen). To handle all that additional heat, they’ll need new ultra-high-temperature (UHT) engine materials. The need for new UHT composites for future hypersonic missiles was recently described [4]. These materials benefit turbine engine and RDE propulsion components. Also described are enabling UHT materials for nosetips and hypersonic aeroshells [4]. With these additional propulsion system improvements, could greater than Mach 12 HCMs be developed? Absolutely!
Maneuverable reentry vehicles (MaRVs) are essentially ballistic warheads that are adapted to have a greater maneuverability during the terminal phase. Unlike old warheads, they are capable of maneuvering and retargeting during flight. Because they have no propulsion system during midcourse and terminal phases, loitering is not an option for these weapon systems. Once launched, there’s a brief window of opportunity for use. They do have an advantage of rapid deploy ability as a weapon platform due to mostly using existing technology. In a nutshell, they come in hot, fast, and short-lived. It could be argued that launching a hypersonic missile with a rocket, akin to an ICBM, is like killing a fly using an elephant gun!” It’s also too expensive to be practical.
Boost glide vehicles (BGVs) share some similarities with MaRVs. They can be launched by rockets, but not ICBM-like missiles. BGVs, while descending at extremely high Mach numbers initially, must slow down to be maneuverable and thus become targets of interception. Rockets initially accelerate BGVs but then they “glide without power to their targets.” High maneuverability and high Mach numbers appear to be mutually exclusive using both current BGV and MaRV technologies. “BGV maneuvering during its glide phase can result in substantial costs in range and glide speed [1].” The US needs a breakthrough for BGVs to meet broader mission requirements and technology to avoid countermeasures.
Whether it’s HCMs, MaRVs, or BGVs, speed and maneuverability really matter to avoid current defensive systems. This is especially true in lower altitude endo-atmospheric flight. Achieving high Mach numbers in this flight regime to mitigate countermeasures means extreme frictional heating of nosetips and aeroshells. For HCMs specifically, the propulsion system also needs to be capable of handling these extreme operational conditions. For all three variants of hypersonic missiles, the US needs much more than off-the-shelf legacy materials. Fortunately, we have the newer and better materials ready to meet this challenge [4].
So what should the US do? Play it safe or go boldly? I’m clearly in the “go boldly” camp. When Ronald Reagan launched the Strategic Defense Initiative in 1983, with his now famous “Star Wars Speech,” he wasn’t playing it safe. He was daring greatly. He helped usher in the collapse of the Soviet Union because of it. In 1962, when John F. Kennedy challenged our nation to put men on the moon, he was daring greatly. Kennedy said it best himself, “We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard.” Hypersonic missiles are indeed very difficult. Emboldened by inspired leadership, the US has always achieved greatness. If we are to surpass our chief rivals, China and Russia, we need leadership with the firm resolve to dare greatly in hypersonics.
Graphic is an eye catching single-stage-to-orbit (SSTO) high-hypersonic concept vehicle.
- Hypersonic Weapons Review (Wright and Cameron):
- Aviation Week Network Link:
- GE Aerospace Press Release:
- MATECH UHT Hypersonic Materials Link:
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ACHIEVING HYPERSONIC GREATNESS “Go big or go home” is an aphorism familiar to the fitness world. It’s also the philosophy of visionary entrepreneurs like Elon Musk and Steve Jobs. You can’t do great things by pursuing modest goals. In the words of Emerson, “Greatness appeals to the future.” When it comes to hypersonic missiles, is the US aiming to achieve greatness?