The Korean Central News Agency reported on 4 October that Kim Jong Un said, following what the North Korean described as test-flights of a hypersonic weapons system, that a very important technology task in the defence of the country had been conducted.
To engineers and defense technologists, the headline label is the least important compared to the design tradeoffs that are concealed within it. Speed Hypersonic is commonly used colloquially as a term for speed, although sustained control, sensing and survivability at high speeds through dense atmosphere are more consequential issues, which fall at the culture of materials science, guidance, propulsion and quality of manufacturing.
The tests that North Korea referred to were defined by Pyongyang as an assessment of readiness and competence of its deterrence to war, and Kim requested to keep on improving its offensive forces. External observers have also raised the question that test articles by North Koreans have not proven the speed- and maneuver performance alluded to in the term. Although that argument remains open, the engineering themes are evident and similar throughout the world programs: maintaining a vehicle intact, steerable, and targetable at hypersonic regimes is a more difficult challenge than momentarily reaching a Mach limit.
1. Hypersonic is categorical problem preceding it is a problem of speed
The definition that is most commonly reiterated in the public is that hypersonic is Mach 5, however, this physical definition of Mach does not remain the same at altitude as the speed of sound varies with temperature and air density. Because Mach 5 is commonly considered to be hypersonic speed, Mach 5 number may be associated with varying real speeds, depending on the position a vehicle is traveling.
This results into a continuing gap in message: most of the old ballistics systems reach Mach 5 in certain sections of their flight, but are not what experts refer to as hypersonic weapons. Technically, the differentiator is usually maneuvering in the atmosphere which is meaningful over significant fractions of the flight, not just a peak speed value.
2. The aspect that propels the engineering bill is maneuverability
The importance of maneuverability to defense planners is that once a vehicle is able to change direction in the air it is harder to intercept. However, the trade-off of that advantage is harsh design penalties: greater control authority, heavier structures, more advanced onboard computation, whilst operating in a hostile thermal environment.
During the thickening process in very high velocities, the amount of heat that flows is very high and may overpower the traditional structures. Things and heat shielding should withstand heating and the pressure brought about by maneuvers. The actuators, power systems and control surfaces should be operable whilst the airframe is being unevenly heated.
3. Guidance can be moved by plasma and heat to become the bottleneck
When the hypersonic vehicle passes through the air, ionization of the flow may occur and form a plasma sheath at hypersonic regimes. That effect is not only a thermal problem, but can be used to corrupt sensors and communications, limiting the extent to which the vehicle can see, and what it can get sent to it externally.
Practically, hypersonic systems require the use of high quality inertial sensing, strong onboard computation and control logic that will remain able to navigate accurately at the time the external signals are unavailable. According to SIPRI, the engineering issue of glide vehicles may be similar to the re-entry to the atmosphere, except that the size and weight constraints are more stringent and the glide vehicles need to control their positions precisely.
4. The difference between hypersonic glide and the hypersonic cruise alters what should be mastered
The term Hypersonic weapons system may mean any of the architectures and the architecture defines the subsystem that is the hardest. Analysts usually distinguish between systems in which the vehicle has significantly boosted speed and then becomes unpowered and glides through the atmosphere (hypersonic glide vehicles) and those where the vehicle is propelled through its entire flight (hypersonic cruise missiles). SIPRI presents this difference between hypersonic glide vehicles and hypersonic cruise missiles as a vital step to comprehending claims of capabilities.
The glide vehicle places a heavy burden on thermal protection, aerodynamics and high accuracy navigation during an unpowerful very stressful period. A cruise missile introduces the need of a propulsion system that has the ability of sustained hypersonic flight, which drives programs to advanced levels of ramjets or scramjets. SIPRI notes that the use of a scramjet engine in a missile system has yet to be implemented by any state, and propulsion has been a bottleneck technology with regard to most cruise concepts.
5. The range numbers are not disclosing compared to flight profile and repeatability
The state media of North Korea reported that missiles hit the targets 1,000 km away. The range figures can contribute to the limiting of the booster and energy budget, but not to decide the question whether the flight in question was accompanied by some maintaining atmospheric maneuvering, which altitudes were followed, or how the vehicle could be stable under heating and loads.
In the case of systems of hypersonic classes, profile-based evidence is usually the most diagnostic: the time period during which the vehicle was in the air, the manner of its maneuvers, and the possibility to repeat the same behavior in the tests. This is among the reasons why many external evaluations are wary whenever states release images and distance statements: performance is shown by the patterns of numerous flights, rather than single statements.
6. Air and sea delivery engineering is associated with the wider modernization drive
The hypersonic messages have come with other revelations and pictures of the North Korean undersea plans, such as images that seem to depict the advancement of a nuclear-powered submarine, which was being built. Images of Kim in state media were of him examining a submarine in an indoor facility and stated that the displacement was 8700 tons, a size that would necessitate a large amount of shipyard capacity and systems integration.
In one of the accounts of the imagery, nuclear-powered submarines have the ability to remain submerged over a long duration which alters the manner the use of a missile power could be utilized and how it could be monitored. To the engineering audience, the similarity between hypersonic and naval nuclear development lies in the aspect of industrial discipline: reactor integration, quieting, thermal management, precision manufacturing, and quality assurance. This is not one breakthrough but sequential competencies that are developed in the process of testing and through the capacity to take failures without breaking the program.
The emphasis, quoted by Kim on the constant modernization of offensive weapon systems subjects the subsystems to the technical burden of being hard to counterfeit: thermal protection, which is non-ablative, guidance systems, which are accurate to plasma and vibration, and control systems, which operate in high load conditions, can remain stable. The latter are the characteristics that make the difference between hypersonic being still a label or being operational category.
