3 ms·

Because, in this case, the incoming weapon dictates the fight. If you are chasing something down (think air-to-air missile) then every turn by the target allow

Because, in this case, the incoming weapon dictates the fight. If you are chasing something down (think air-to-air missile) then every turn by the target allows the missile to catch up faster via a shorter path and smaller turn (a2+b2=c2, the missile follows c). A 45 degree turn by a fighter jet might mean only a few degrees turned by the sidewinder missile fired from behind. But with a hypersonic coming towards and the interceptor being slower, the opposite of a classic dogfight, the opposite becomes true. A small turn by the hypersonic means a larger turn by the intercepting missile to get to the new intercept point. If you draw the triangle then the intercept path is C, but the shorter of A or B. The hypersonic is following the longer of A or B.

whiddershins 5y ago
Are interceptors always slower and why?
- sudosysgen 5y ago
  For hypersonic weapons, yes. Firstly, the interceptor has to climb up to the altitude of it's target. Then, it has to fly through very thick atmosphere. It also has to do so rapidly enough for it not to be too late. It needs to be much cheaper than the weapon it's intercepting for it to make economic sense, also. Because of this, they won't be airbreathing, and even if they were they would be slower.
  - ALittleLight 5y ago
    I can imagine interceptors fired off near the enemy launch site that run down the hypersonic while it's still accelerating. Or, interceptors fired down from space either at the incoming hypersonic or along an expected path intending to converge.
    - sudosysgen 5y ago
      There's two problems with your first idea. The primary issue is that such an interceptor would need to be more expensive and more capable than the missile it's gonna hit, not even taking into account all of the supporting infrastructure necessary. The second issue being that if you're going to be operating near (horizon distance, so let's say 200km) of a missile launch site, you're going to be bombed or missile'd to smithereens. If you can prevent that, you could just bomb the launch site to begin with. As for interceptors fired down from space, you'd need to expend all the energy to get them into orbit, and then expend the energy to get them back into atmospheric flight, which itself is going to be 10x more expensive than it's target. There's also the issue that while in suborbital flight, the hypersonic missile can just adjust it's trajectory a bit and the whole trajectory is now useless.
  - thfuran 5y ago
    >It needs to be much cheaper than the weapon it's intercepting for it to make economic sense, also. Certainly it would be nice if it were cheaper than the incoming missile, but doesn't it really just have to be cheaper than whatever the missile is targeting for it to make economic sense?
- sandworm101 5y ago
  One is falling down from space, the other climbing up. Imagine if I threw a brick off a building. You are on the street and see that the brick is going to hit one of two babies. You might be able to jump in front of the brick in time to collide/intercept the brick, but there is no world where you would be moving upwards anywhere as fast as an object falling from great height. Now imagine the brick can move to avoid you and instead hit the other baby. The brick changes course after you jump. That's what is happening with a hypersonic diving onto a target.
jhgb 5y ago
> A 45 degree turn by a fighter jet might mean only a few degrees turned by the sidewinder missile fired from behind. This is true for some "classic" guidance laws (such as proportional guidance), but is it true for optimal guidance? Especially for point defense? Your "small vs. large turn" becomes an issue of transverse acceleration, and that makes the advantage of the hypersonic vehicle way lower, if not non-existent (since to my knowledge hypersonic lifting bodies don't exactly shine in the lift-to-drag ratio department, so it's far from clear that an interceptor would be unable to match transverse acceleration, and in any case it might be able to force enough velocity loss on the hypersonic vehicle that it may have to work way harder to hit the target even if it's not actually hit by the interceptor at all).

whiddershins 5y ago

Are interceptors always slower and why?

sudosysgen 5y ago
For hypersonic weapons, yes. Firstly, the interceptor has to climb up to the altitude of it's target. Then, it has to fly through very thick atmosphere. It also has to do so rapidly enough for it not to be too late. It needs to be much cheaper than the weapon it's intercepting for it to make economic sense, also. Because of this, they won't be airbreathing, and even if they were they would be slower.
- ALittleLight 5y ago
  I can imagine interceptors fired off near the enemy launch site that run down the hypersonic while it's still accelerating. Or, interceptors fired down from space either at the incoming hypersonic or along an expected path intending to converge.
  - sudosysgen 5y ago
    There's two problems with your first idea. The primary issue is that such an interceptor would need to be more expensive and more capable than the missile it's gonna hit, not even taking into account all of the supporting infrastructure necessary. The second issue being that if you're going to be operating near (horizon distance, so let's say 200km) of a missile launch site, you're going to be bombed or missile'd to smithereens. If you can prevent that, you could just bomb the launch site to begin with. As for interceptors fired down from space, you'd need to expend all the energy to get them into orbit, and then expend the energy to get them back into atmospheric flight, which itself is going to be 10x more expensive than it's target. There's also the issue that while in suborbital flight, the hypersonic missile can just adjust it's trajectory a bit and the whole trajectory is now useless.
- thfuran 5y ago
  >It needs to be much cheaper than the weapon it's intercepting for it to make economic sense, also. Certainly it would be nice if it were cheaper than the incoming missile, but doesn't it really just have to be cheaper than whatever the missile is targeting for it to make economic sense?
sandworm101 5y ago
One is falling down from space, the other climbing up. Imagine if I threw a brick off a building. You are on the street and see that the brick is going to hit one of two babies. You might be able to jump in front of the brick in time to collide/intercept the brick, but there is no world where you would be moving upwards anywhere as fast as an object falling from great height. Now imagine the brick can move to avoid you and instead hit the other baby. The brick changes course after you jump. That's what is happening with a hypersonic diving onto a target.

jhgb 5y ago

> A 45 degree turn by a fighter jet might mean only a few degrees turned by the sidewinder missile fired from behind. This is true for some "classic" guidance laws (such as proportional guidance), but is it true for optimal guidance? Especially for point defense? Your "small vs. large turn" becomes an issue of transverse acceleration, and that makes the advantage of the hypersonic vehicle way lower, if not non-existent (since to my knowledge hypersonic lifting bodies don't exactly shine in the lift-to-drag ratio department, so it's far from clear that an interceptor would be unable to match transverse acceleration, and in any case it might be able to force enough velocity loss on the hypersonic vehicle that it may have to work way harder to hit the target even if it's not actually hit by the interceptor at all).