Comment on The M.I.D. is mid by sacredcow

Parent Post: The M.I.D. is mid · In Reply To

sacredcow · 3/12/2025, 12:23:15 PM · permalink

Hypersonic describes speeds exceeding Mach 5 (5 times the speed of sound, or 3,836 mph). This includes vehicles like missiles, aircraft, and even spacecraft that can travel at these high speeds.

Here's a more detailed explanation:

What is Hypersonic Speed?

Definition:

Hypersonic flight, in terms of speed, means traveling at or above Mach 5.

Mach Number:

Mach number is a measure of speed relative to the speed of sound. Mach 5 is 5 times the speed of sound.

Speed:

Hypersonic speeds are typically considered to be 3,836 mph (6174 kilometers per hour) or higher.

Atmosphere:

Hypersonic flight can occur within Earth's atmosphere or during atmospheric entry from space.

Hypersonic Systems and Applications

Hypersonic Vehicles:

Hypersonic vehicles can include aircraft, missiles, glide vehicles, and spacecraft.

Military Applications:

Missiles: Hypersonic missiles are designed to travel at high speeds, potentially making it harder to intercept them.

Glide Vehicles: These are typically boosted into the upper atmosphere and then glide to their target at hypersonic speeds.

Aircraft: Development of hypersonic aircraft is ongoing, aiming for faster travel times over long distances.

Space Applications:

Hypersonic technology plays a role in spacecraft design, such as during re-entry into the Earth's atmosphere.

Challenges

Hypersonic flight presents engineering challenges like dealing with extreme heat and developing materials that can withstand these temperatures

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mr.t · 3/12/2025, 12:47:24 PM · permalink

So the simple explanation is the function/relevance of a hypersonic missile is a maneuverable missile that does not engage in a ballistic trajectory (so not straight up into space and then straight down), and is thus more maneuverable than a traditional ballistic missile, occupying a niche in between cruise missiles and ballistic missiles.  
Cruise missiles depend upon maneuverability and low altitude flight (curvature of the Earth) to avoid detection and thus interception.  
Ballistic missiles depend upon speed, at the cost of more predictable, high altitude trajectories, that can be detected from much farther away.  
The point of hypersonics is to deliver a payload at a high mach number at a lower altitude, where the speed of the vehicle is not as dependent upon gravity and a simple ballistic trajectory.  
Air is more dense at lower altitudes, so it is a bigger engineering challenge to sustain Mach 5+ speeds the lower the missile flies. Your traditional ballistic missile basically boosts itself into space and uses gravity to help it come back down to Earth at great speed.  
'Hypersonic Missile' isn't a precise scientific term, with a precise definition, so every government from China to North Korea claims to have a 'hypersonic' missile, but a Mach 5+ ballistic missile doesn't qualify. As you've noted previously, such is the domain of ballistic missiles.  
What makes hypersonics special is the altitudes (and maneuverability) at which they fly and the difficulty that this imposes on detection and interception mechanisms.

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sacredcow · 3/12/2025, 1:13:29 PM · permalink

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mr.t · 3/12/2025, 1:21:15 PM · permalink

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sacredcow · 3/12/2025, 1:30:40 PM · permalink

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