Gary Lerude of Microwave Journal recently spoke with Dave Slack, Engineering Director at Times Microwave Systems, on hypersonic weapons. Watch the complete video or read the session notes below.
Hypersonic weapons have been a hot topic in the news lately. Please give us some background on hypersonics and what all the buzz is about.
A really quick definition of hypersonic is that it describes any speed faster than five times the speed of sound (above Mach 5). The hypersonic weapon systems creating all the buzz today will go faster—about 10, 15, 20, or even 25 times the speed of sound.
Hypersonic technologies are not new; however, they have been around for 70 years or so since the end of World War II. Examples include Sputnik, the Apollo missions, SpaceX rockets, etc. What they all had in common is that they have a ballistic path, a parabolic arc set by the force of gravity and launch velocity. The path is very predictable, and it is easy to determine where the vehicle came from, where it’s going to land, etc., so it’s easy to defend against and countermeasure.
The difference today is that the new generation of hypersonic vehicles is steerable. This makes it challenging to determine precisely where it came from, which is a game changer. The weapon system that is getting the most attention right now is hypersonic glide vehicles. These are initially launched on a parabolic or ballistic arc but can drop down much lower in altitude mid-course and “glide” at a relatively low atmosphere at hypersonic speeds. As a result, they are much more challenging to detect.
Not only are these missiles traveling at hypersonic speeds, but they are also maneuverable. As a result, the time to react could be as little as two-three minutes compared to 45 minutes or an hour with other missile types, so they are very difficult to defend against. Additionally, there are hypersonic cruise missiles, powered vehicles with a scramjet or a supersonic ram jet. That is another game changer because it can travel at much lower altitudes at much longer ranges and is powered, so it’s not just gliding.
Given the physics associated with hypersonic speeds and the extreme environmental conditions, what kind of challenges or emerging technologies have hypersonics created?
The maneuverability factor is the primary issue when it comes to electronics. Every time the missile maneuvers, it loses energy, which is then dissipated as heat. This is in addition to the heat caused by the friction of slipping through the air stream. Dealing with that heat is one of the significant technical challenges.
Smart weapons are also precise and accurate, usually requiring someone on the ground to identify a target, communicate with the weapon, and guide it at hypersonic speeds. These vehicles are surrounded by a plasma envelope, which is why space vehicles lose communications for a few seconds on re-entry because the envelope shields them from communications. Penetrating the plasma envelope to communicate with the weapon and steer it creates another big technological hurdle. This drives the need to evaluate smaller, lighter options that can operate at higher temperatures.
RF microwave technology is used on hypersonic weapons in onboard systems for communication, as well as detection and countermeasures. I expect the RF microwave community will play an increasingly important role in countermeasures.
Do you have a sense of the market evolving over the next few years as research and development turn into actual fielded programs?
The armed services and government development agencies rely on industry to develop these weapons, components, and underlying technologies. As a result, a lot of investment will flood into this space because it is the department of defense’s number one development priority right now and will likely continue to be a top priority for at least the next ten years.
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