What does hypersonic mean? I thought all missiles were largely supersonic, except for maybe cruise missiles.
Aerodynamics is a practice of which physical phenomena you can ignore. At low speeds you can pretend the speed of sound is infinite / air is incompressible (these are equivalent), as you get faster you have to start paying attention to compression, then shock waves, heating, ionization, and the mechanics of individual particles.
Mach 25 is approximately orbital velocity, but since Mach is actually related to air pressure, it's not a very meaningful comparison except to note that anything moving that fast isn't going to be in-atmosphere for very long.
In transonic flight, some parts of the airflow are starting to become supersonic, and compressibility starts to become a factor. Something called "wave drag" is important in this regime, as the compression wave is moving along with the aircraft.
In supersonic flow, compressibility of the air becomes the main thing and the flow is defined by the positions of the various shock waves. Ramjet engines work in this regime (the aircraft is moving fast enough that the forward movement is enough to compress the incoming air to the engine, without compressor blades). In a conventional ramjet engine, the flow within the engine is subsonic (the compressed air, being more dense, moves more slowly within the engine), so combustion works the usual way.
In hypersonic flow, temperatures are getting very high (air is heated by compression). Scramjet engines become a thing (the "SC" is for supersonic combustion: air flowing through the combustion stage at supersonic speed).
0 - The reasons are due to maximum allowable pressures, and barrel rifling. At max pressure for a 40gr bullet you’re going to get maybe Mach 1.1, maybe. If you want to go faster without increasing pressure above spec, the solution is a lighter bullet. But lighter bullets often like different rifling, and virtually all off the shelf 22lr barrels come with 1:16 rifling, unsuitable for extra light bullets. Also, lighter bullet get pushed around by the wind more; you’d often rather compensate for more drop than wind, since drop is more predictable.
Specifically CIP sets the maximum pressure of 22lr at 24,646 psi. An extremely high number considering, but pretty pedestrian compared to other cartridges. For example NATO sets a maximum pressure of 62,366 psi for its primary rifle caliber, 5.56x45mm. It’s genuinely amazing that rifle barrels don’t regularly explode, to be honest.
Water vapor content, not being a diatomic gas does very slightly change the speed of sound but usually to a degree which can be ignored.
(people generally don't believe that the speed of sound in air depends only on temperature when you tell them)
https://www.gao.gov/blog/faster-speed-sound-u.s.-efforts-dev...
These weapons represent an ability for both the US and China to conventionally intervene from their mainlands to any location within the Pacific.
This would likely mean the weapon hits its non-mainland target prior to the other side taking notice for a retaliatory strike. In the event the other side did notice - it's likely they wouldn't treat it as a nuclear incursion unless the weapon was heading inland towards missile silos or other infrastructure that would motivate a nuclear retaliation.
To your point on stranded assets - these weapons make performing any large military action in the pacific much riskier with greater probability for missteps or stalemates. Assuming a cost of 20-100 million dollars per missile I wouldn't be surprised if they are cost competitive with high risk carrier based F-35 operations in a hypothetical Pacific conflict. It's probably cheaper to stock pile such missiles than maintain additional carrier strike groups for the sole task of participating in a great power conflict.
Why not? If it was carrying a nuclear payload and was destined for strategic sites on the mainland, it could be too late to retaliate if they waited to see where it is going, particularly if it was aimed inside the first island chain.
If China detected nuclear capable missiles heading toward their country then they would have to consider the possibility their second strike capability is not a sufficient deterrent (including being compromised in various ways such as their subs being all located) so there seems like a large incentive to retaliate before missiles land.
Would there be enough time for them to watch and wait it out and see if it approached their missile installations? If it was a very stealthy missile, could they be sure they had detected them all?
The concept of nuclear triad is that, yes, armies very strongly depend on their second-strike capability. So, the game is for the subs to not to become compromised.
> We are not in the 1960s when at times it was literally true.
You are claiming that not only China, but the US and Russia don't have the capability of launching strikes from 30 minutes? (i.e., well beyond the time to respond to ballistic missile launch detection)? Do you have a source for this?
This doesn't appear to agree with you:
https://www.mitpressjournals.org/doi/pdf/10.1162/ISEC_a_0021...
Launch-On-Warning
One source of ambiguity in the implementation of China's no-first-use policy is the ongoing debate in China regarding the pursuit of a launch-on-warning posture. Recent doctrinal publications and Chinese interlocutors indicated that the debate has yet to be resolved. On one side, some members of China’s strategic community argued that a launch-on-warning posture would ensure the survivability of its nuclear deterrent if its opponent has robust targeting intelligence. The Science of Military Strategy states that a launch-on-warning posture "is in accordance with China's long-standing no-first-use policy, and may effectively protect China's nuclear forces from sustaining even greater losses, improving the survivable nuclear counterstrike capability of China’s nuclear missile forces." China's first priority should be to prevent its adversary from precisely locating its missile launch positions. If China is able to reliably ascertain that an adversary has already launched nuclear missiles at China, however, China could quickly launch its nuclear missiles for a counterstrike "before the enemy has been able to actually inflict nuclear destruction." Launch-on-warning would therefore provide China with an option for nuclear retaliation if a nuclear adversary were able to overcome Chinese efforts at concealment, deception, and mobility to ensure that its forces survived a first strike.
What you cited is sad, but firstly it is still an "ongoing debate", and secondly the road from declarations to the actual ability is long with this one. And may it never materialize again.
Do you have a source for that?
The sibling comment says Russia and USA have a prompt alert which can launch in under 15 minutes. Other articles say the US president could be contacted and approve in under 30 seconds, not sure how the Russian chain of command goes.
The decision process does not begin when nukes are detected of course, that's the end of the process. Pre agreed criteria have already been met. Quite likely there is no decision about entering a full scale nuclear war because they are already in one.
> These weapons represent an ability for both the US and China to conventionally intervene from their mainlands to any location within the Pacific.
Is that the kind of range these have? Almost 9,000 miles from LA to the South Western most corner of the Pacific. If you meant the North Pacific then even the western edge of the US to the yellow sea is over 5,500 miles.
Ballistic missiles of course have these kind of ranges and can carry conventional payloads.
Just call while the missile is on the way to let the people it's going to kill know its not a nuclear bomb headed their way so they shouldn't fire a nuclear bomb back.
For this particular weapon, a somewhat similar weapon I can think of is the European Meteor [2], which is ramjet (rather than scramjet) powered, and reaches Mach 4, rather than over Mach 5 as this one is supposed to do. Meteor comes at a cool cost of EUR 2 MM per piece. Think about it, you fire one missile like that, and it's like destroying 10 Ferraris.
[1] https://www.flightglobal.com/flight-international/8-key-hype...
But, like, really cool.
A ballistic missile is often quite supersonic. But cruise missiles being hypersonic is definitely a big shift.
Still kinda surprised there aren't fast missiles that use rocket engines. It works for ICBMs? I don't see a reason they couldn't maneuver as well. Maybe the hypersonic regime makes things novel not just for propulsion but control too.
Air-breathing engines are able to save all that mass by using atmospheric oxygen.
This matters, because it's the rocket equation in reverse: no onboard oxidizer = lighter vehicle = less fuel needed = even lighter vehicle = longer range / more payload
this device is almost certainly air breathing. there's simply too big an oxygen-breathing-demand at speed to do anything else for sustained high speed flight, where you need to be generating a lot of motive force.
People imagine how drones are going to change everything. Cruise missiles are already bomb shaped drones...
And existing bombs get "drone" capability...
All ballistic missiles are hypersonic. The V-2 was hypersonic. That's because range is directly dependent on speed and you wouldn't have basically any range if you had a mere supersonic speed.
For an unpowered flight, it is a rather meaningless term, but normally refers to maneuvering warheads on ballistic missiles
The oldest definition of hypersonic I have heard is those speeds where compression heating of the atmosphere ahead of the craft generates plasma. A space capsule on reentry hits such speeds, causing the classic radio blackout. So hypersonic aircraft are those that must deal with plasma-related issues that are irrelevant to slower supersonic aircraft.