Supersonic AShM vs Subsonic AShm

[big toothbrush]

at current state of the art subsonic SSM is indeed more efficient than supersonic one.

1) supersonic SSMs have to fly a high trajectory to maintain long distance trip, coz at low altitude air is much more dense than at high altitude. supersonic SSM will run out its fuel very soon when flying low trajectory due to resistance from air.

any high altitude object is easy target for SAM. the higher you are means you are above the horizon to farer enemy, enemy could detect you earlier, and have more reactive time.

while subsonic SSM could have a whole trip low-altitude flying. without support from airborne sensors, you can't detect it untill the missile got close to a distance that 30~50km far from you. this is the average horizon view range for shipborne radars.

2) supersonic SSMs have more obvious IR signature and bigger RCS than subsonic SSMs', which means the latter one would have less chance to be detected.

3) supersonic SSMs can't fly as low as subsonic SSMs even in terminal phase. supersonic SSMs' high speed causes stochastic high pressure from air. trajectory shiver would happen, plus the high speed, supersonic SSM is very easy to crush with water if it flys as low as a subsonic SSM.

normally a supersonic SSM flys 30m high in terminal phase and only reduce to 5m in the last 1km of the trip. while a subsonic SSM flys 3~5m high in terminal phase. this also mean the latter one would have less chance to be detectd and shot down. this also mean the latter one would have less chance to be detectd and shot down.

4) supersonic SSM's seeker has to stand a more atrocious working environment than subsonic SSM's seeker does. thus even if their seekers have the same size apertures, the latter one's would have more chance to lock on target.(actually in most cases supersonic SSM's seeker has smaller aperture coz it has to save space to carry much more fuel)

5) supersonic SSM's reflected radar waves have more obvious doppler frequency shift than subsonic's coz supersonic SSM has higher relative speed to enemy's radar. it means it's more easy to pick supersonic SSM's signals from background disturbed signals such as radar waves reflected by water.

most time you can lock a supersonic SSM once it's above horizon. but it's very hard to lock a stealthy subsonic SSM. you can't continuously track it coz its signatures are very weak and always hide in the background disturbed signals. you can catch its sinatures, but brokenly. those are not enough to support a lock process. so when the time you successfully lock a subsonic SSM and launch the interceptive SAM, the incoming SSM is almost only 20~ 30km away from you. the reactive time left to you is actually always short than some supersonic SSMs'.

conclusion is subsonic SSMs will be more deadly than supersonic SSMs untill above problems to be solved. and this is also the reason why american navy hasn't used any supersonic SSM in battle yet.

[big toothbrush]

here's video about thai navy tests chinese c-801 and french mm-38. subsonic AShM terminal trajectory could be as low as 3m.
http://www.youtube.com/watch?v=TCeTYbMty1U

[contedicavour]

Very interesting topic, thanks for bringing it up.

Beside the USN, all Western navies rely on subsonic SSMs as well :
> Exocet MM40 (in its extended version it goes a lot beyond its initial 70km range)
> SCALP Naval, cruise missile mostly conceived for land attack but technically usable against ships as well. Range 300km+
> Teseo Mk2A, 180km range minimum (a Mk3 is being developed for 300km range)
> Norwegian NSM, a sort of extended range Penguin
> Swedish RBS SSMs, with the latest version adopted by the German Navy on K130 corvettes having a range of 200km.

All these are subsonic. Efforts are being made to extend range, not speed.

Only the Russians (Yakhont/Onix for example) and the Indians (Brahmos and the Klub) give maximum priority to supersonic missiles. Rumours are around that the Chinese YJ83 & YJ62 may have terminally supersonic speeds, but there is no proof at all of that. The Chinese have however bought 4 Sovremenny DDGs with Sunburn supersonic missile.

So who has taken the better option ? Russia-India or the Western powers ?

cheers

[DoC_FouALieR]

While I agree with you, there are some points that disturb me..

so when the time you successfully lock a subsonic SSM and launch the interceptive SAM, the incoming SSM is almost only 20~ 30km away from you. the reactive time left to you is actually always short than some supersonic SSMs'.

However, there are only a few ships in a task force that carry SAMs with a range exceeding 15 km, so in massive strike, supersonic ASMs could achieve better results. (that was the soviet doctrine)

thus even if their seekers have the same size apertures, the latter one's would have more chance to lock on target.(actually in most cases supersonic SSM's seeker has smaller aperture coz it has to save space to carry much more fuel)

Usually, supersonic ASMs have a larger diameter than subsonic ones, so they can carry a larger radar antenna. Moreover, most of supersonic missiles use a ramjet or a turboprop for their propulsion, allowing the use of an alternator in order to produce the onboard electrical current needed to operate the electronic and sometimes the actuators, whereas in exocet-type missiles, electrical current is provided by a thermal battery, so the seeker is likely to be less powerful on subsonic missiles than on supersonic ASMs.

But after all, only a real engagment could give us the right answer...

[powerslavenegi]

A subsonic terrain hugging missile will be the choice of any Armed forces when engaging land based targets (for the landscape and terrain provides an excellent env. for evading detection until last 5-10 Km) also it will be practically impossible for a missile to maintain a supersonic flight and at the same time follow the ground contours,However in case of anti ship roles the terrain mapping ability is of little use I believe a Supersonic sea skimming missile would have an edge over it's subsonic counterpart.I do not think in a battlefield a ship would be engaging another sea based vessel in excess of 400km or so.Hence a supersonic Ashm with a low flight trajectory and a range of 200Km or so would be a potent weapon.The point I want to make is a Supersonic missile at a height of 5m above water doing mach 3+- and a subsonic at 3mtr. have same probability of getting detected by the target vessel,but the chances of shooting down the subsonic missile are more than the Supersonic one.Moreoever a direct hit by a 3 Mach projectile would be catastrophic phew .

[Aussie Digger]

Originally Posted by powerslavenegi

A subsonic terrain hugging missile will be the choice of any Armed forces when engaging land based targets (for the landscape and terrain provides an excellent env. for evading detection until last 5-10 Km) also it will be practically impossible for a missile to maintain a supersonic flight and at the same time follow the ground contours,However in case of anti ship roles the terrain mapping ability is of little use I believe a Supersonic sea skimming missile would have an edge over it's subsonic counterpart.I do not think in a battlefield a ship would be engaging another sea based vessel in excess of 400km or so.Hence a supersonic Ashm with a low flight trajectory and a range of 200Km or so would be a potent weapon.The point I want to make is a Supersonic missile at a height of 5m above water doing mach 3+- and a subsonic at 3mtr. have same probability of getting detected by the target vessel,but the chances of shooting down the subsonic missile are more than the Supersonic one.Moreoever a direct hit by a 3 Mach projectile would be catastrophic phew .

Did you watch that video? The 2nd missile was the subsonic Exocet and it went straight through the target and out the other side, the first missile simply exploded upon impact. Which one hit harder kinematically???

[contedicavour]

Interesting discussion.
The point is : what is the flight trajectory (meters above sea level) of today's best supersonic missiles (Sunburn, Yakhont-Onix, Brahmos, Klub) versus the best subsonic ones (latest Harpoon and MM40 Exocet, Teseo Mk2A) ?
It's pretty logical that if the 2 missiles were flying at the same height above sea level then they would be intercepted at about the same time by the defending ship. Then the supersonic missile would leave less time to defend oneself.
However, if the supersonic flies higher, it will be seen sooner and that reduces the advantage speed gives it.
In terms of impact damage, it's more the size of the warhead that matters, more than the speed at impact.
One last thing that matters : if your enemies have supersonic missiles, you'd better have longer range CIWS guns and missiles. A Phalanx isn't enough for example : even if it destroys the target 1.5km away, bits of the missiles could still damage the ship.

To summarize : I still prefer a very low-profile large-warhead subsonic missile with high manoeuvring capabilities rather than a supersonic missile. But just in case I'd make sure my ships have long range anti-missile missiles (Aster 15s have proven they can stop missiles at 15-20km away ) and heavy artillery CIWS (hence our 76/62SR with Dardo-F)

cheers

[RA1911]

Originally Posted by contedicavour

> Norwegian NSM, a sort of extended range Penguin

I just want to point out that the NSM is quite a bit more than an extended range penguin

[SU 30MKI]

Lets Takes an example :

1) If super sonic missile detected at 50 Km from ship then :
a) its travelling speed around @1000m/sec
b) distance from ship 50x1000m= 50,000m
c) so missile travelling @1000m/sec will hit the ship afte 50 sec

2) If subsonic missile is detected at 15 km from ship then
a) its travelling speed around 240m/sec
b) distance from ship = 15x1000 =15,000m
c) so missile travelling @240m/sec will hit the ship after 62 sec

Even after that supersonic missile gives less time to defend

http://en.wikipedia.org/wiki/Harpoon_missile
http://en.wikipedia.org/wiki/BrahMos

see the effect of supersonic missile
http://img45.imagevenue.com/img.php?loc=loc63ℑ=18489_SER.jpg

[Mangusta CBT]

Originally Posted by contedicavour

(a Mk3 is being developed for 300km range)

Where read this news ?

[DoC_FouALieR]

2) If subsonic missile is detected at 15 km from ship then
a) its travelling speed around 240m/sec
b) distance from ship = 15x1000 =15,000m
c) so missile travelling @240m/sec will hit the ship after 62 sec

Hmm, subsonic missile use to fly a bit faster...
The Exocet flies around 300 m/s, however, when detected at 15 km, it still allow a response time of ~ 45 s before impact.

And like I said before, you surely can detect a supersonic missile 50 km, but if you don't have long range SAMs, you are forced to wait until the missile comes in range of the defence system...

However, a subsonic missile can be detected far away of the ship if the task force is using some AWACS or REMRO (remote radar operation)

At this point of the discussion, it seems that the respectively advantages and drawbacks of subsonic and supersonic missiles are more or less balanced...

So it is now a matter of doctrine...

[kilo]

Originally Posted by SU 30MKI

see the effect of supersonic missile

The effect is irrelavent in comparing subsonic missiles in general to supersonic missiles in general. The effect depends on the size and type of warhead which doesnt have anything to do with the missile being supersonic or not.

[SU 30MKI]

Originally Posted by DoC_FouALieR

Hmm, subsonic missile use to fly a bit faster...
The Exocet flies around 300 m/s, however, when detected at 15 km, it still allow a response time of ~ 45 s before impact.

And like I said before, you surely can detect a supersonic missile 50 km, but if you don't have long range SAMs, you are forced to wait until the missile comes in range of the defence system...

However, a subsonic missile can be detected far away of the ship if the task force is using some AWACS or REMRO (remote radar operation)

At this point of the discussion, it seems that the respectively advantages and drawbacks of subsonic and supersonic missiles are more or less balanced...

So it is now a matter of doctrine...

Well Supersonic missle is hard to bring down due to its speed againt sun sonic speed. Especially agaist guns, last line of defence

[DoC_FouALieR]

Well Supersonic missle is hard to bring down due to its speed againt sun sonic speed.

Hmm... not really I think, because sub- and supersonic missiles fly a straight path and are incoming, and since supersonic missiles use to be bigger, it is a target of choice for SAMs.
In this case the speed is not going to help the missile dodge the defence.

[Grand Danois]

A Stinger could perhaps do it. But IMV the weakness is in the manual cueing and aiming of the missile. If the missile operator gets a visual from say 15 km away till the AShM hits he has perhaps 16-17 seconds before impact, and an envelope of less than 4-6 seconds to get the lock, fire and hit the AShM.

Could the Mistral and Stinger take down a AShM? Well, even if the MANPAD missile itself has the parameters for taking down the AShM in a head-on engagement, it would definitely need an automated engagement system.

It goes too fast for a human to close the kill chain.