9 ms·

But maneuvering at high velocities won't be that easy. As far as I understand it, your lift/drag ratio decreases appreciably with increasing Mach numbers. So ei

by jhgb 5y ago

But maneuvering at high velocities won't be that easy. As far as I understand it, your lift/drag ratio decreases appreciably with increasing Mach numbers. So either you'd have to limit your maneuvering, or you'd have to have a propulsion unit with ridiculous amounts of thrust - at a situation when any amount of useful thrust is hard to obtain, since we still don't know really well how to do propulsion in this regime.

JumpCrisscross 5y ago
As a former aerospace engineer, I’m sceptical of the strategic value of hypersonics. Tactical? Sure. They’d have a better chance of taking out SAMs, light radar, et cetera. But the talk about these being carrier killers is, based on everything we’ve seen, off the mark. (Spending the cost of one hypersonic on a swarming attack would probably do more damage.)
- sudosysgen 5y ago
  The biggest difference between hypersonics and swarms of slow missiles is that the hypersonics can get there fast enough that you might not need high-quality targeting information. That's definitely a strategic advantage! Also the 3M22 is estimated to only cost around 2 million dollars.
  - JumpCrisscross 5y ago
    > hypersonics can get there fast enough that you might not need high-quality targeting information The strategic systems hypersonics are hyped to hit have been hardened against ballistics. Hypersonics are slower than ballistics. (Their plasma envelope also makes them easier to track by satellite.) This is a tactical evolution. Meaningful. Helpful. But not a strategic shift.
    - sudosysgen 5y ago
      The big issue is that a ballistic missile may not be able to deviate as much from the expected position as it can search away from it. I agree that they're not that different from ballistics but they still have considerable advantages.
  - jhgb 5y ago
    > that you might not need high-quality targeting information I don't see how this would work, unless of course you're talking about nuclear weapons. With a conventional warhead you still need to hit your target.
    - sudosysgen 5y ago
      You can locate your own target if it's close enough - say 10-30 miles or so - from where you expected it to be. With a slower missile your target will have drifted a lot more.
- nurgasemetey 5y ago
  I think taking out SAMs is huge thing. Or I am wrong?
  - canadianfella 5y ago
    Did you read the rest of the comment?
- redis_mlc 5y ago
  As a student of war, anything you target at the enemy just might work, especially with the element of surprise. The best example is the Exocet(s) that hit the Stark in the Falklands War: - the Stark had a temporary commander from a sub. He was unable to organize the fire-fighting (damage control) effort, which is the biggest threat to a ship. The US Navy prides itself on training every member of the crew on damage control, especially after the 1967 Forrestal fire: https://en.wikipedia.org/wiki/1967_USS_Forrestal_fire https://en.wikipedia.org/wiki/1967_USS_Forrestal_fire - the Stark had electronics problems, with the radar system interfering with radio transmissions/reception. You could argue that the ship was blind, even non-operational. - one of the Exocets did not detonate, but destroyed a ship - the kinetic energy and remaining rocket fuel was enough. - the air-launched Exocets used improvised rails, since the French embargoed parts. So you never know if a powerful missile will be intercepted in time or not, which is magnified with nuclear warheads. Oya, and the Falklands was the best ad ever for Aerospatiale! Ironically, the US Sidewinder missile won the second Taiwan Straits War. The CCP stopped the air battle after the Taiwanese AF downed multiple jets with the Sidewinder, the first time it was used in battle. (Note the USSR always talked down the CCP when they were on the losing end, rather than allowing them to escalate further.) The Sidewinder was and is one of the most lethal weapons ever invented, true "fire and forget."
sudosysgen 5y ago
Thrust is not the issue, the issue is net thrust. Essentially the missile/engine is compressing so much air that trying to get more air to produce more thrust doesn't work, you have to manage to increase efficiency, by increasing compression, without melting or blowing apart your engine Once you manage to make significant net thrust making a bit more isn't that big of deal, it's really a critical point you have to pass.
- jhgb 5y ago
  Yes, that's what makes it even worse. Flying as fast as you can means you have very little reserve for velocity losses from extensive maneuvering.
- JumpCrisscross 5y ago
  > once you manage to make significant net thrust making a bit more isn't that big of deal You’re still limited by your fuel and flight envelope. The latter which bleeds the former. Hypersonic missiles will be harder to intercept than cruise missiles. Due to their novelty, they’ll also be harder than ballistics. (Ballistic projectiles don’t continuously illuminate their flight path. That permits for subterfuge options an air-breathing missile forfeits.)
  - sudosysgen 5y ago
    These maneuvers are in the terminal phase. Knowing the reaction speed and the moment at which LOS is achieved as well as estimating the speed of the missile and it's acceleration one can calculate a relatively short period under which interception is possible. Outside of that there is basically no risk and thus no need for any maneuvers. As for flight envelope we know from the X-15 that not that much is required to pull 10Gs at hypersonic speeds. There is no need for much more.
    - JumpCrisscross 5y ago
      > maneuvers are in the terminal phase One, this leaves the missile, which is screaming through the atmosphere, vulnerable in a way ballistics are not. (And visible in a way cruise missiles aren’t, either.) Two, if you have a carrier strike group in the middle of the ocean, this strongly restricts how much manoeuvring can be done. The target knows where you’re ultimately headed—if you tactfully manoeuvre into a blank patch of ocean, the strike group is fine. > flight envelope we know from the X-15 that not that much is required to pull 10Gs at hypersonic speeds The flight envelope restriction isn’t a structural one. If you have a known target, there is only so much manoeuvring the vehicle can aerodynamically do without slowing down to sub-scram speeds. Yes, you could supercharge the engine, but that cascades through another host of factors.

by jhgb 5y ago

JumpCrisscross 5y ago

As a former aerospace engineer, I’m sceptical of the strategic value of hypersonics. Tactical? Sure. They’d have a better chance of taking out SAMs, light radar, et cetera. But the talk about these being carrier killers is, based on everything we’ve seen, off the mark. (Spending the cost of one hypersonic on a swarming attack would probably do more damage.)

sudosysgen 5y ago
The biggest difference between hypersonics and swarms of slow missiles is that the hypersonics can get there fast enough that you might not need high-quality targeting information. That's definitely a strategic advantage! Also the 3M22 is estimated to only cost around 2 million dollars.
- JumpCrisscross 5y ago
  > hypersonics can get there fast enough that you might not need high-quality targeting information The strategic systems hypersonics are hyped to hit have been hardened against ballistics. Hypersonics are slower than ballistics. (Their plasma envelope also makes them easier to track by satellite.) This is a tactical evolution. Meaningful. Helpful. But not a strategic shift.
  - sudosysgen 5y ago
    The big issue is that a ballistic missile may not be able to deviate as much from the expected position as it can search away from it. I agree that they're not that different from ballistics but they still have considerable advantages.
- jhgb 5y ago
  > that you might not need high-quality targeting information I don't see how this would work, unless of course you're talking about nuclear weapons. With a conventional warhead you still need to hit your target.
  - sudosysgen 5y ago
    You can locate your own target if it's close enough - say 10-30 miles or so - from where you expected it to be. With a slower missile your target will have drifted a lot more.
nurgasemetey 5y ago
I think taking out SAMs is huge thing. Or I am wrong?
- canadianfella 5y ago
  Did you read the rest of the comment?
redis_mlc 5y ago
As a student of war, anything you target at the enemy just might work, especially with the element of surprise. The best example is the Exocet(s) that hit the Stark in the Falklands War: - the Stark had a temporary commander from a sub. He was unable to organize the fire-fighting (damage control) effort, which is the biggest threat to a ship. The US Navy prides itself on training every member of the crew on damage control, especially after the 1967 Forrestal fire: https://en.wikipedia.org/wiki/1967_USS_Forrestal_fire https://en.wikipedia.org/wiki/1967_USS_Forrestal_fire - the Stark had electronics problems, with the radar system interfering with radio transmissions/reception. You could argue that the ship was blind, even non-operational. - one of the Exocets did not detonate, but destroyed a ship - the kinetic energy and remaining rocket fuel was enough. - the air-launched Exocets used improvised rails, since the French embargoed parts. So you never know if a powerful missile will be intercepted in time or not, which is magnified with nuclear warheads. Oya, and the Falklands was the best ad ever for Aerospatiale! Ironically, the US Sidewinder missile won the second Taiwan Straits War. The CCP stopped the air battle after the Taiwanese AF downed multiple jets with the Sidewinder, the first time it was used in battle. (Note the USSR always talked down the CCP when they were on the losing end, rather than allowing them to escalate further.) The Sidewinder was and is one of the most lethal weapons ever invented, true "fire and forget."

sudosysgen 5y ago

Thrust is not the issue, the issue is net thrust. Essentially the missile/engine is compressing so much air that trying to get more air to produce more thrust doesn't work, you have to manage to increase efficiency, by increasing compression, without melting or blowing apart your engine Once you manage to make significant net thrust making a bit more isn't that big of deal, it's really a critical point you have to pass.

jhgb 5y ago
Yes, that's what makes it even worse. Flying as fast as you can means you have very little reserve for velocity losses from extensive maneuvering.
JumpCrisscross 5y ago
> once you manage to make significant net thrust making a bit more isn't that big of deal You’re still limited by your fuel and flight envelope. The latter which bleeds the former. Hypersonic missiles will be harder to intercept than cruise missiles. Due to their novelty, they’ll also be harder than ballistics. (Ballistic projectiles don’t continuously illuminate their flight path. That permits for subterfuge options an air-breathing missile forfeits.)
- sudosysgen 5y ago
  These maneuvers are in the terminal phase. Knowing the reaction speed and the moment at which LOS is achieved as well as estimating the speed of the missile and it's acceleration one can calculate a relatively short period under which interception is possible. Outside of that there is basically no risk and thus no need for any maneuvers. As for flight envelope we know from the X-15 that not that much is required to pull 10Gs at hypersonic speeds. There is no need for much more.
  - JumpCrisscross 5y ago
    > maneuvers are in the terminal phase One, this leaves the missile, which is screaming through the atmosphere, vulnerable in a way ballistics are not. (And visible in a way cruise missiles aren’t, either.) Two, if you have a carrier strike group in the middle of the ocean, this strongly restricts how much manoeuvring can be done. The target knows where you’re ultimately headed—if you tactfully manoeuvre into a blank patch of ocean, the strike group is fine. > flight envelope we know from the X-15 that not that much is required to pull 10Gs at hypersonic speeds The flight envelope restriction isn’t a structural one. If you have a known target, there is only so much manoeuvring the vehicle can aerodynamically do without slowing down to sub-scram speeds. Yes, you could supercharge the engine, but that cascades through another host of factors.