Anti-ship Ballistic Missiles (ASBM)

I searched alittle for info about decreasing CEP of ballistic missiles to hit acarrier or alarge -medium ships... ,

i got some different answers, optical guidance is fine but not for targets like aship in sea (for short range ballistic missile ),

First of all look at what other anti carrier missiles use for guidance... options include anti radiation. When defending itself during an actual attack most vessels will turn on their radars once they know they have been spotted because the advantage of having radars turned on and being able to spot targets and threats from long range is much more useful than having them off and making the opponent wonder if that is really you or not.

If the attack has already started then hiding is not the best option because they have likely found you.

Other options include radar, IIR and optical. Very few would rely on GPS or coordinates only simply because one of the main features of ships is that they can move.

All of these options would be relevant to an incoming ballistic missile so using one or a combination of several might be useful.

Radar guidance is very good but i have no info that if it enough to hit ashiip or not (for SRBM)

Radar guidance is all weather, but it is also active and warns the target it is under attack.

combining GPS will be excellent ,but GPS will be bolcked by USA on war time

Actually GPS would not be that much use because most ships move... a target 300km away moving at 25knts is not going to be in the same place when your missile arrives.

im interested in this idea after watching the iranian anti ship short ballistic missile,i wondered how can they hit aship with that accuracy,,

An undefended stationary ship... optical or radar guidance would both work well.

I guess CEP here must be around 10 meters !!
the lowest CEP of ascud as i remember was 50m ,

Lowest CEP of original Scud was more like 1km... which was fine for its purpose... delivering chem or bio agents or nukes to large NATO structures like airfields or troop concentrations. For Iraqi modified Scuds it was 2-5 times bigger CEP.

Scud had no terminal guidance so CEP gets much worse with distance travelled.

i also guess that 10 m CEP require using GPS, iranian didn't use GPS...

US military GPS guidance would be fine for this test, but real targets will be moving so GPS would not be much use unless you had a platform tracking the target and continuously updating the weapon... what sort of platform could survive that close to a carrier?

after looking to the rounded warhead,i think they used radar guidance or optical guidance or combined them together ??

For a supersonic weapon you want a pointed nose if you can help it... aerodynamically it is better. This suggests this weapon has optical guidance.

Iskander is a 300km range ballistic missile with options that include optical and radar guidance.

Am surprised they didn't fit a pointed fairing over the nose that fell off in flight to allow terminal optical homing but with better launch and cruise aerodynamics.

but how they achieved this acuuracy without GPS ?
or they just lie

GPS "guidance" guides things to fixed positions in space. It works in 3 dimensions... LAT LONG, and ALT. An anti ship guided missile needs to work in 4 dimensions... LAT, LONG, and ALT and Time to get a hit with GPS.

The calculation is quite difficult and prone to error... when you spot a carrier you need to get its exact position and heading and speed and based on the time it will take for your missile to arrive you can estimate the ships future position when the missile arrives... assuming the target will not change course or speed.

CEP would be 100m plus even without thinking about the effect of cross winds etc.

Much easier to locate the target and fire the missile into the area where it is going to be and then as the missile is falling activate an optical sensor or radar scanner to look for targets and then use the control surfaces to manoeuvre to fall onto the target.

if they didn't lie,iranians would become the first country to hit aship with short ballistic missile ( for my memory )

It will needs some very sophisticated bits to make it effective. Sinking a ship is about being sneaky... you are far more likely to sink a ship because it didn't know it was under attack in the first place. A ballistic missile flys so high it will probably be detected at very long range, so even though it is moving rather fast it becomes a maths problem to shoot it down. Modern computers are very good at maths.

If the target is an oil tanker then you will likely get a kill if you get a hit. An AEGIS class cruiser on the other hand has SAMs that can hit high speed objects flying high...

They could fake by having a radio emitter on the ship.

Quite true. Or they could be lasing the target with a laser target designator LTD.

The question is... what is this weapon for? If it is a political thing to say to the Iranian people and their neighbours that Iran is not defenceless against the mighty US Navy, then such tricks and cheats make sense... a hit is worth more than anything else that might have happened if they had not cheated... though I dare say if they had missed we would not see the footage...

I read some sources about 50 m CEP of N.K hwasong6 (scud c mod)...

I would suggest they got that level of accuracy through one or a combination of three ways.

Either they fired it at a very short range so it didn't have enough flight time to build up positional errors, or they added a guidance package that helped it get closer to the target than it otherwise should have, or it is merely propaganda... either from the North Koreans to pretend they know better than other Scud users or from the US who are desperate to make North Korea sound like a real threat despite the fact they are working with Scuds which are pretty much dumb simple ballistic rockets from the 1950s that are really no more effective than the V-2... which means it is fine against an enormous city like London, but not much use against anything smaller.

I rather suspect it is the latter reason.

Having big bad powerful North Korea there justifies a significant US military presence in both South Korea and Japan, and the rocket technical prowess of NK can be used to make all sorts of claims about Iran and their potential to make huge strides in rocket technology performance. A house of cards really.

Not that I think North Korean scientists and engineers are idiots, but they are pretty much isolated from the rest of the world economically, politically, socially... having to do everything yourself is slow and expensive.

I think they will use it against oil ships in gulf, low speed ,unwarned and undefended target would be good to hit...

And if Iran decided to close the gulf such ships would be their primary target so a ballistic missile with a range of 300km or so would be ideal located in the northern part of the Persian Gulf as ships could not skirt around it.

but i'm interested in CEP , I always believe that ballastic missile can't hit aship !!!

but seems that guidance systems are in ver high rate of development to make SRBM to hit aship !!

The Russians are getting CEPs of 20m or less with optical guidance for Iskander... against a ship at sea it should be rather easier as there are fewer objects that might distract the seeker. They would still need a very accurate position for the target ship and its speed and course. Ships operating in groups in a convoy with military ship protection will be much harder targets... and of course there might be the worlds first deployment of F-22s to fly along the Persian coast looking for launch positions.

i know iran has anice ballistic program but don't know they get anice tech like this,
i think they are the first to do something like this .

It is an interesting new use of ballistic missile technology, but unfortunately for them the Iraqi use of Scud and modified Scud missiles in Desert Storm made the west suddenly realise it was vulnerable to even fairly basic ballistic missiles and so for the last 20 years they have been working at the problem on land and at sea so a ballistic anti ship missile will likely not come as a huge surprise now.

I think the fact that they are publicising it suggests they probably realise that it would already be something that could be countered, but they are trying to intimidate their neighbours and countries that don't have naval SAMs with the performance to defeat such threats.

Not a bad move really... set up a simple practise with a missile homing on a beacon... take lots of photos and watch your neighbours spend billions upgrading their navies air defence capacities while you probably actually spend money on something like shore based long range torpedo launching facilities. 650mm torpedoes can be used over enormous ranges with a lower speed setting of something like 35 knots. Not good enough for most military targets but for a 16 knt tanker it would be fine and the enormous power of a huge 650mm torpedoes warhead should make one or two hits enough for a kill.

Light isn't effected by magnetic fields.

Extreme gravity yes, but not magnetic fields.

When you use a very powerful magnetic field it can effect anything... not just metals.

I have seen a very high power magnet suspend a strawberry in the air.

The main problem is polarity... if you use a magnetic field to defend your ship what is to stop the enemy firing magnetised weapons at you... half will be repelled but half will be attracted...

That's why the US Space Shuttle is on it's last flight. They now can build the next generation ship able to have a force field, repel asteroids from it....big booster rockets no longer needed to get into space.

The replacement for the shuttle will not be ready for at least half a decade and will not be powered or propelled by magnetic fields.

(The Space shuttle is on its last flight because it is so enormously expensive to launch.)

the missile range is 300 km ,it's not areal ballistic path,it's atactical missile ,so it has low time to maneuver using fins to hit the target which mean low accuracy as i think !!

In this case a ballistic path is not important... in fact a ballistic path to target is much more predictible and therefore vulnerable to defences.

A Tomahawk cruise missile can be used as a tactical missile that doesn't follow a ballistic path and its accuracy is reportedly pretty good.

The point is that this missile will be fired in the direction of the target like an artillery shell.

Unlike a dumb artillery shell this missile presumably has some sort of sensor to detect where the target actually physically is in relation to its flight path. A simple guidance system can be used to deflect the control surfaces as the missile falls through the air to turn the weapon to a new course that lands it closer to or on the target.

The accuracy will depend on a lot of factors, like how close to the targets real position the missile was falling towards... obviously the closer the better and that comes from how accurately the targets projected position when the missile arrived was calculated.

The control surfaces will not be able to turn the missile 90 degrees unless they use side thruster rockets, so there will be a limit based on time to manouver that the missile can change its trajectory to a new trajectory that will hit the target.

A good example would be a 152mm laser guided artillery shell. You can't just fire it off in any direction and expect to get a hit just because someone is pointing a laser at the target for you.

You set up an ambush where the enemy armour has to go through... like a main road through a marsh or a bridge over a deep and fast river.

In the bridge case you will target it as a choke point and aim all your 152mm guns at the bridge. Without using a laser most rounds will land on or near the bridge, but obviously you need a direct hit with a 152mm shell to kill an armoured vehicle so from your lasing position you will be able to lase targets out to about 10km, but from the time the little protection cap falls off the guided 152mm shells till the shells impact the ground they can only manouver out to 2km away from their point of impact. That means that a 2km radius circle around the bridge is your kill zone. If the terrain is clear then you want to work out the wind speed and direction... first of all because that will effect the shells and move that radius of impact, and second because if you hit several tanks closest to you the smoke might make targeting tanks behind them very difficult.

When all the tanks start popping smoke then your battery can switch to standard HE and try and drop the bridge.

There are several synchronisation computers involved... is it not just some guy with a hand held laser pointing from target to target as the shells are fired.

With a direct communication link to the battery the guy with the laser target marker will aim very carefully at the roof of the target and the artillery battery will fire a shell. With the trajectory calculated the computer at the laser marking end will actually turn on the laser for the final 3 seconds of the trajectory which means that suddenly a laser will hit the vehicle and 3 seconds later bang. The laser target marker (LTM) guy will either bug out or continue to mark targets with 20-30 seconds between shells to allow time to pick out new targets. Obviously the LTM is not limited to marking vehicles... he could mark a group of soldiers or a building or the bridge.

For Russian direct fire weapons that use laser guidance generally the target is lased for one second. You still aim at the target and in the last second side thruster rockets are generally used to throw the projectile onto the right trajectory for a hit.

Note laser beam riding weapons are much different and do not use the same principles.

For example a laser beam riding missile has its sensor looking back at the launch vehicle and does not look at the target. Because the sensor is looking at the laser beam the laser beam can be up to 10,000 times weaker than a beam directed at a target that a laser homing weapon has to detect the reflection from. It doesn't matter how shiny or what colour the target is or if there is smoke around the target because the laser goes from the launch platform to the missile and not from the launch platform to the target (through the smoke) and back to the missile.

if iranians want to get low CEP they should make it with separating warhead...

Depends on the configuration... if the large control surfaces are on the body of the missile then dumping them leaves you with less control.

For a weapon to use against an object the size of a ship extra mass is not a bad thing.

Remember for all the Exocet hits in the Falklands war there is no real evidence that any of the missiles warheads actually exploded, so the ships taken out by the missiles were taken out by fires started by the pure impact of the weapon and perhaps remaining fuel and warheads burning.

Dropping 20 tons of steel at 3-4 times the speed of sound... remember an explosive warhead in an IED mostly kills by accelerating steel to 3-4 times the speed of sound making it shrapnel.

A decent sensor that can detect and accurately guide the falling missile onto a target along with control surfaces that allow it to manouver as it falls is all it really needs.

but tomahawk has nice accuracy coz it is different in design from the iranian one ,tomahawk has wings on the middle of it's body,which means high maneuver to hit targets then high accuracy..

No.

Tomahawk has wings half way down its body to support its weight in flight... ie to give it lift like an aircraft.

The wings don't steer the missile it is the control surfaces at the rear of the Tomahawk that determine its rate of climb or turn.

iranian one has no wings ,it has fins (may be able to make anice maneuver,the designer is the one who could confirm that ).

You are confusing terms. A wing is a structure that might be fixed or moving that generates lift in flight to support a flying body. It could be the fixed wing of an airplane, the rotary wing of a helicopter, or the moving wing of a bird or insect.

A fin is used either as a stabiliser like the fixed fins on a missile that don't move, or as a control surface that does move and can redirect the flight path of the vehicle.

Think of a sidewinder missile. Any model. The front mounted canard fins move to turn the nose and also the seeker towards the target. The rear mounted fins are fixed and ensure a consistent and smooth airflow around the rocket motor.

Think of the R-77 missile. Long slim fixed body strakes that ensure stable airflow around the missile body that aide body lift at high speed while rear grid fins that can rotate in flight to steer the missile at the target by pushing around the tail.

Ballistic missiles generally have small fins for low drag and more often than not have directed rocket thrust using lots of methods like graphite vanes in the rocket exhaust or a flexible exhaust mount to ensure the proper flight trajectory. For the terminal phase however thrust vector control is useless because the engine has no fuel left.

Small canard controls or side thruster rockets are some of the methods used to hit point targets. ICBMs can have CEPs of 25m over flight ranges of tens of thousands of kms, they tend to have separating warhead bus's that direct warheads on flight paths to hit targets but the current Russian ICBM warheads are self propelled and self guiding.

This weapon seems to hit the target intact, so perhaps those rear fins have control surfaces. Due to the speed even relatively small controls could be used as long as used accurately and early enough and the original ballistic path gets you right on target.

When was the last time you saw a plane in level flight with its wings at that angle?

Very low speed at an airshow with its nose up nearly in a stall?

The wing shape is designed to generate lift in level flight in he correct speed range for the aircraft. The wing is positioned near the centre of gravity because that is the centre of the weight of the aircraft so it simply makes sense to lift in one place where the weight is centred. Control surfaces in other places like horizontal tail surfaces and canard foreplanes do not help with lift they are there for control.

Fins are also for control.

Ballistic vehicles do not use wings except to extend range.

The Tomahawk is a cruise missile, not a ballistic missile.

A ballistic... anything... missile, bullet, rock is launched upwards and then falls back down.
A cruise missile is powered during flight and uses wings to remain airborne.

This Iranian weapon is a ballistic weapon.

The Russian Iskander is a ballistic weapon with a relatively small CEP that does not have wings... it has tiny fins at its base.

The Russian Tochka is a ballistic weapon also with a relatively small CEP that has body mounted strakes and tail mounted grid fins.

A wing generates lift but also creates drag so to use a wing effectively you need a constant propulsion system to balance the drag.

A fin merely sticks out into the airflow and either creates stability by making the airflow over the missile more uniform and stable, or it moves to divert the airflow to create a force on the missile to turn it in flight.

At very low flight speeds fins and wings are useless, so for example the cold launch of a TOR or Brahmos the weapon is blasted up by the launch system and then small rockets in the nose of the missiles fire to turn the nose of the weapon toward the target and then more rockets fire in the opposite direction to stop it turning too far and the main rocket lights up and blasts the missile towards the target.

The low flight speed means fins and wings are useless so side thruster rockets need to be used to control the missile.

With a ballistic missile travelling at very high speed there is an enormous amount of air blasting past the body of the missile so even a small fin sticking out into that airstream can generate quite a lot of force by turning and redirecting some of that air.



Here is the Iskander-E system. It has a range of 300km and a small CEP quoted at 50m using just Inertial guidance down to less than 10 using all sorts of guidance methods.

The only control surfaces are the small tail mounted fins and they seem to be stabiliser fins that are fixed. The missile itself is guided initially by thrust vectoring rocket propulsion, with terminal homing effected by powerful side thruster rockets. No wings and no GPS because it is propelled at over mach 5 and the civilian GPS doesn't work above about 850km/h.

The problem with the Iranian AShBM system is it's range (thus speed). For example, the Chinese DF-21D is a based on a MRBM, whilst the Shahab-2 is based merely on a Tactical Ballistic Missile. Subsequently, their ranges are about so, 3,000 km for the DF-21D, and a mere 750 km for the Shahab-2. The DF-21D has almost 3 times the range of the Shahab-2, and far more terminal velocity.

Agreed, in a dive attack like that even Phalanx could probably get it... it has shot down mach 2.5 Vandal targets in 45 degree dives. The point is that there is plenty of warning and no radar returns off waves like with low flying targets...

I suspect the actual targets will be oil tankers.

Talos Rim 8 has steering wings

To be effective wings they need to be horizontal...



They look like fins to me.

how ? it's range 300 km ,it will not take afull ballistic path and will not reach aballistic height, For ranges less than 350 km, the ballistic missile never leaves the Earth’s atmosphere ,i think it could be just 20km height ...

I don't follow you.

122mm calibre Grad rockets are ballistic rockets and in their early models had flight ranges of 20km and never left the atmosphere either.

Most ballistic missiles are launched vertically and use gyros and engine deflection to lean into the correct trajectory to head to the target. Obviously the precision it can do this to plus external factors like wind speed and direction will all effect accuracy on target if there is no terminal guidance. With terminal guidance any errors can be corrected and accuracy improved. For instance a Scud with a CEP of 1km at 300km but fitted with terminal homing might get within 10m or less of a target if the guidance is accurate and the flight algorithm is effective and the control surfaces start working early enough to allow enough time to manoeuvre onto the actual targets position.

I don't think INS can achieve CEP of 50 m,, acombination of GPS and INS give that 50 m ,,and mix of GPS and INS and electro-optical can give 30to 10 m ,i'll quote that

Using a ring laser gyro the Su-24M2 is able to keep to within 20m of its actual position over several hours and over 1,000km of flight range.

I don't think INS can achieve CEP of 50 m,, acombination of GPS and INS give that 50 m ,,and mix of GPS and INS and electro-optical can give 30to 10 m ,i'll quote that

That is a JANES report based on estimates. The company that makes the equipment cites the Maximum error... ie 99% error as being up to 200m... in other words severe wind in different directions at different altitudes from launch to impact... which both never happens and is a higher error standard than most commonly used. Normal CEP is 95% error and to convert 95% error to 99% error you need to multiply the CEP by 4. To convert back you need to divide by 4... and up to 200m divided by 4 is 50m.

Let me put it this way... if the Iskander could only use INS guidance and satellite guidance and GLONASS is not global coverage yet why are so many countries interested in Iskander?

If as you say even Scud D gets 50m CEP over 300km do you really think Iskander would be actually 4 times worse accuracy wise?

The claims for the optical guidance were 20m for a while then after testing they were revised to 10m because in testing the actual CEP was 7m or so.

what is the best INS accuracy achieved to our days ?

Depends how much you want to spend. Fibre optic gyros get their accuracy from the length of fibre optic cable they contain and some of them have dozens of kms of cable. Expensive, but accurate.

can really INS take iranian missile to avery near region from the target to let he optical guidance to hit it , or they need GPS to achieve higher accuracy ?

50 m CEP not enough to hit aship ,i think.....

The point is that no one relies on INS only guidance except with a nuclear warhead against an area target. A CEP of 500m is fine as long as the terminal guidance starts to zero in on the target more precisely and there is time to manouver the whole weapon onto the target.

It is like launching an AMRAAM at a target... the AMRAAM carrys its own radar and ability to find and intercept a target so even if it arrives 10km short of the target when it turns on its radar and scans for its target it will still find it and use its onboard radar to fly an intercept course and hit the target... a 10km CEP is not accurate at all but good enough in this case.

Mathematically, how ?

Is this 95% standard ? why they didn't mention that ??

There is no such thing as 100% CEP.
In other words CEP is a measure of error... or how far from the aim point any given launch will achieve.
Some use an error of 50%, while others prefer the 95% error. The 99% Error is rarely used because it results in a larger CEP to cover most things except failure to launch.

CEP means nothing without the error level.

A CEP of 100% would be fairly useless because 100% covers all possible eventualities... like failure to launch and also exploding instead of launching... in which case the CEP for a missile with a range of 300km has a CEP (100%) of 300km... ie draw a circle with a radius of 300km and 100% of the time the missile will end its flight somewhere inside that circle.
This is the most precise and most useless method of measuring accuracy because it tells you little about the likely result of a real shot at the target.

CEPs are more commonly used in 50%, 95% and 99%.

With missiles it is generally the 95% level that is given because that excludes all the failures to launch or exploding booster meaning the weapon fails to get to the target area.

Think of a bell curve... if you cut off 25% at each side then the remaining 50% of the bell area contains the majority of the data. It is good enough to find an average result. If you only cut 2.5% off each side then you include most of the main stream data and remove the extreme scores (both high and low) which gives you a better picture of what should be a normal result of firing the weapon.

Firing lots of nuclear armed ballistic missiles at US ships is not really the best solution for combat... the response will likely be nuclear armed ballistic missiles too.

Yeah, but the thing is that they wont be sure they are conventionally armed till impact and if they shoot them down in flight they wont know whether they were conventionally armed or armed with nukes till they can check the debris for radiation.