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Posted: Dec 15 2011, 01:54 AM
1% Armaments Designer
Member No.: 1,068
Joined: 23-February 11
The Nenda-12 is a high supersonic/hypersonic cruise missile developed by the Tehraanian military to replace the P-800 Oniks and Brahmos cruise missiles it initially used. With a top speed of Mach 5.23 and a range varying between 300-400km depending the on variant and flight mode. It serves as the main 'intermediate range' weapon under the current Unified Navy's naval warfare doctrine. The Unified navy reporting name is 'Comet.'
Length: 8.9 m
Wingspan: 1.2 m
Diameter: 0.67 m
Launch Weight: 3600 kg (ground launched) 3100 kg (air launched)
Speed: Mach 4-5 (max Mach 5.23 at altitude)
Range: 300-400km depending on flight mode and launch altitude
Guidance: INS/GPS with terminal active-radar homing and home on Jam (version A), enhanced Satellite navigation (version B ) or Passive radar-homing (Version C).
Warhead: 300kg semi-armor piercing high explosive (version A), 350kg High explosive (version B and C) or VN-1 variable yield nuclear warhead (between 0,1-20kt).
Propulsion: One or two staged Solid-Rocket fuel booster with liquid fuel ramjet.
Development and Concept
In a relatively short time the Tehraanian military command forced massive changes and modernization of its naval forces. A massive failure of its initial naval operations showed the inadequacy of its naval tactics and doctrine in the type of naval combat it was faced with. Which at the time were based on experience gained during the 2nd civil war, where all naval combat took place in littoral waters.
Despite the development and production of Tehraan's early versions of Mikalen cruisers and Tsatem destroyers, it became painfully apparent neither these could prepare Tehraan's naval commanders for the harsh reality that their current weaponry, technology and tactics weren't cut for naval combat far away from Tehraan. Causing an extraordinary loss of live for which they weren't prepared.
It wasn't until the new naval doctrine was fully devised and set on paper by one of its most renowned Admirals, Admiral Yamegalet Minan that the new tactics and organisation they had been forced to develop became official.
Fresh out of the New Korongo Civil war. Yamegalet had brought for the first time a major naval battle that was a victory for the Tehraani side. Dispelling any doubts about Tehraan's capabilities to be a sea power. After which he wrote his new book on this revision of naval strategy, tactics and doctrine.
The P-800 and PJ-10 missiles were at that time Tehraan's main anti-ship missiles and while they proved usefull during the Korongo civil war and other operations against the brimstone pact. It was deemed necessary that to continue a replacement had to be domestically developed. One that would be more fitting in both the demands for the Unified armed forces of the Hegemonic Union and it's new naval warfare doctrine. This would allow for better performance and production capabilities. Thus significantly boosting its maritime power.
The missile itself is designed as an intermediate range weapon under Tehraani naval doctrine. That means it operates in a region that lies between the short and long range which in measurements is about 250-500 km away from a Tehraani naval force.
It follows a similar design concept to the P-800 or PJ-10 and on the exterior might be mistaken for either. Yet differs greatly from both missiles in details of its exterior and its internal design. Like both however it hangs on the idea of achieving defence penetration through speed and in that it far out achieves both.
However speed comes at the cost of both range, payload and increased weight due to the requirements that are needed for the missiles to achieve its speed. Because of that the missile hasn't got a significantly stronger warhead than smaller, more common and subsonic anti-ship missiles, yet is much larger than these because it has to devote a lot of its weight and size into its ramjet engine and fuel tanks to have the range needed to be effective.
It is none the less very effective at penetrating the defences of enemy surface groups. The speed of the missile decreases the reaction time available for enemy defences to shoot down the missile. That means that the time from detection to impact is shorter than slower anti-ship missiles. In that time the enemy can try to either use soft-kill or hard-kill counter measures in an effort to prevent the missile from hitting its target.
The sheer speed of the missile however leaves little time for said defences to do their job. Moreover with a terminal speed between Mach 4-5, gun based point-defences like the phalanx or Goalkeeper CIWS are practically useless and missile based point-defences like RAMs and Tor missiles would have a hard time intercepting the Nenda-12 before it hits.
The only hard-kill measures really effective are long range missiles or highly-advanced missiles and those are not guaranteed protection. The low reaction time either means very few missiles can be fired to protect a ship when ammunition is conserved, or it has to fire large amounts at the same time to increase the chance of a successful interception of the Nenda-12. Which in turn depletes the available missiles for its defence far quicker, leaving the ship vulnerable to further attacks.
Increased resistance against soft-kill measures like radar jamming and chaff is gained through the radar it uses for active radar homing. Which is further elaborated on in that section.
The basic Nenda-12 design exists in two stages. A solid rocket fuel booster brings the missile to a desired altitude (which varies between version and attack profile) and a speed of Mach 4+. At that point the booster detaches and the liquid fuel powered ramjet takes over, which provides it with sustained high speeds at increased fuel efficiency.
A Ramjet is an air breathing jet engine that in terms of construction is fairly simple due to its lack of complex parts. It lacks the rotary compressor vans seen on turbo jets engines which simplifies the design and allows for greater speeds to be achieved. But they require considerable forward motion to push the air into the jet and are unable to produce thrust at slow speeds or a standstill.
Typically a ramjet powered cruise missile is designed around its inlet and the Nenda-12 is no different. By virtue of being derived from the P-800 and the PJ-10, the Nenda-12 possesses a large inlet at the front of its nose. After the booster does its job the speed of the missile causes the air to get pushed in without the need of a compressor van, by exploiting the dynamic pressure created by the missile's speed.
Under high pressure the air goes through the intake were it recovers the free stream stagnation pressure caused by airflow for combustion and expansion in the nozzle. Inside the combustion chamber several features are present to stabilize the combustion. Such as flame holders preventing the flames from blowing out and a sheltered pilot region that enables the combustion to continue even when the missile undergoes a high yaw or pitch.
Like most ramjets at the back a convergent-divergent nozzle is situated. The nozzle is vital for the missile to achieve its speed, by accelerating the exhaust flow to produce thrust.
The Nenda-12 missile usually operates between Mach 4-5. But is known to go above or below depending on the flight altitude which varies between the two different attack profiles. Initially it was opted to add a scramjet but this caused the missile to be unable to operate at low altitudes, which the Tehraani military commanders desired to be possible. The ramjet can achieve the required speed but is more efficient at lower speeds, so true hypersonic flight is difficult to achieve and maintain for the Nenda-12. During high profile attacks at high altitude however the missile has been able to achieve speeds of Mach 5.23 in its flight.
Guidance system and sensors
At its most basic the main guidance of the Nenda-12 is GPS/INS. An INS or inertial navigation system is a guidance system that uses a computer, accelerometer and ring laser gyroscope to measure it's position, orientation and speed via dead-reckoning without any external references.
The missiles guidance computer is provided with the initial coordinates of its target and from that point calculates its own position from the launching point to its target's predicted position based on the measurement it makes.
The only problem is that this system suffers from integration drift. An inherit systematic error that grows during its flight. Causing the error on its own position and that of its target to be greater the longer it flies, as slight errors in its speed and direction measurements compound.
To partially solve this the guidance computer incorporates a satellite navigation system or GPS that it uses to correct the errors caused by the INS. The GPS gives a drift-free position value that resets the INS of the guidance computer to the corrected position and starts calculating again. This method greatly reduces the error of the INS and greatly improves the accuracy of the missile.
Additionally the missile can receive mid-course updates on the position and speed of its target from an outside source like a reconnaissance aircraft. Although generally the speed by which the Nenda-12 flies is usually too fast to allow for a major reduction in accuracy due to evasive actions taken by its target, especially when that target is a slow moving ship. The mid-course update still adds to the accuracy of the GPS/INS when it comes to target positioning.
In the terminal stage of its flight, the anti-shipping version turns its active radar on about 60km away from the predicted location of its target. The Nenda-12 A anti shipping version uses a high resolution Pulse-Doppler radar.
A Pulse-Doppler radar is a 4D radar system capable of capturing it's target in a 3D location, as well as measuring radial velocity. The Radar relies on the Doppler effect (thus its name sake) to avoid overloading the computer which also has the side effect of reducing the power consumption. The System has the added benefits of improved detection in high-clutter environments and greater track reliability using feedback. This allows the Nenda-12 A to track its target in practically any weather conditions, water types and other situations that would normally make radar tracking hard.
Another added benefit is Pulse-Doppler signal processing, a radar performance enhancing technique that allows the radar to distinguish smaller and faster moving objects near slower or stationary objects. Small fast moving objects can be identified close to terrain, near the sea surface, and inside storms. Unique for a Pulse-Doppler radar is that can it be pointed into regions containing a large number of slow-moving reflectors without overwhelming computer software.
The effect of this is that the Nenda-12 A can home in on its target with little interference from other sources. This means that next to the previously mentioned situations it's also highly resistant to chaff decoys commonly used on ships against anti-ship missiles.
To add extra resistance to ECM, the Nenda-12 A's active radar also possesses a passive-radiation function which provides home-on-jam. Many modern ships possess radar jamming systems for defence against anti-ship missiles . These can prevent a missile from homing in on their target using their radars, thus forcing them to use their INS which decreases accuracy.
Home-on-jam counters this by homing in on passive radar signals. Radar jammers work by transmitting signals to the target radar that interfere with its functions. But in essence these are still radar signals, thus they can be exploited by passive radiation homing.
The home-on jam function is a relatively simple addition to the active seeker. Anti-radiation homing is a homing method that uses a passive sensor to detect and home in on the emissions normally caused by a radar. But it can just as easily home in on the source of jamming signals used by radar jammers. When installed on a missile it allows the missile to home in on the jamming signal's source when the active radar is jammed. This effectively makes the missile immune to the effect of radar jamming at the hands of its target and in practice makes jamming the missile suicide.
The same technology is used on the Nenda-12 C. The Nenda-12 C is the anti-radar variant and like the home-on-jam system of the Nenda-12 A it has a passive seeker, but passive only. The purpose of the missile is to home in on the emission of enemy radars in order to take them out.
It's primarily for use against ground based air defences by eliminating ground based early warning, target acquisition and tracking radars. This gives the Tehraani military added SEAD (Suppression of Enemy Air Defences) strength. Especially with the increasing commonality of air defence systems with long range surface to air missiles, such as the S-400, that out range most ARMs in use.
Lastly theirs also the Nenda-13 B land attack version which lacks any sort of radar. Instead it uses an enhanced version of the GPS/INS which uses GPS to hit it target. Before firing the location of its target is recorded as normal. It homes in on its target by using a GPS fix on the targets location. This allows the missile to hit its target with a circular error probability under 13 meters.
This allows it to hit sizable stationary targets, like enemy supply depots and command structures with extreme accuracy. To counter GPS jamming the missile has its receiver pointed upwards to the sky, to limit the interference of GPS jammers on the ground
There are three different types of warheads available for Nenda-12.
An anti shipping warhead with a 300kg semi-armor piercing high explosive warhead for use against surface ships. The impact speed of the missile means that there's a lot of kinetic energy involved when the missile hits a ship. To increase the penetration probability the missile contains a titanium cone in front of the explosive that protects the explosive and helps during penetration of a ships hull.
A timed fuse system has been fitted to the explosive and the cone. Once it registers that the missile has hit, the timed fuse is activated. It's set to go off after a fraction of a second, with most ships by this time it has enter at best halfway through the hull. At that point the explosive goes off inside the ship, causing major damage in its structural integrity and internal make up.
The land attack and anti-radiation versions instead use a more basic 350kg high explosive against land targets, usually enough to destroy most buildings or soft skin targets it's intended for.
Lastly all versions have a nuclear variant. The Nuclear Nenda-12 are armed with a VN-1 variable yield nuclear warhead.
Variable yield warheads are nuclear warheads that have present yield that can be selected depending on what the operator thinks suits best for the intended target. Via the use of external neutron initiators. These are small particle accelerators which cause a brief fusion reaction by accelerating deuterium into a tritium target (or potentially vice versa), producing a short energetic pulse of neutrons. Precise timing of the ENI pulse as the nuclear primary's pit is collapsing can significantly affect yield, and the rate of neutron injection can also be controlled.
The options are either 0.1kt, 1kt, 5kt, 10kt or 20kt
A ground, ship or submarine launched Nenda-12 is normally launched vertically, although a fixed angle version was used on several old classes of cruisers and is still used on the Tsatem Class destroyers still in limited service. Using a two staged booster it uses the first stage to propel itself out of its launching tube. Then uses its second stage booster to gain speed. At that point it flies according to its flight profile.
The Nenda-12 has a selectable two-style flight profile whom each has its own advantage. A low trajectory mode and high trajectory mode. Both modes offer several advantages but usually come at a cost.
In the low trajectory mode it follows a low flying profile. After launch the missile angles itself close to horizontally using several rockets placed inside the inlet's protective cap. After it's in the right angle, the cap ejects and then the main booster is fired.
During flight the missile gains speed until it reaches about Mach 4 using its booster and follows a horizontal flight path during this stage. After it has expended its booster, it ejects it and starts the ramjet that will give it sustained flight of Mach 5, at an altitude of 14.000m above sea level. At the terminal phase, around 40-60km (during this time the anti-ship version activates it's active radar) away from its target envelop it reduces its altitude to about 10m or 5m (sea skimming) and at a speed of Mach 4 tops although it tends to drop a little below due to difficulty of flying at such a speed at low altitudes. The anti-ship version makes a short increase of altitude to look with its radar again and update the position of the target in the guidance computers shortly before impact.
The advantage of this flight profile is that it flies below the radar horizon of most surface ships or ground based radars used by anti-air batteries. The downside of this however is that high speed is difficult to achieve and sustain with a ramjet at such a low altitude. Resulting in slower speeds then the missiles top speed and a reduced range of 300km.
The second mode is the high trajectory mode. After launch the Nenda-12 immediately removes the inlet's protective cap without putting it at an angle first. Then the second stage booster ignites and sends it off in a ballistic like trajectory instead of a low altitude cruise.
During this flight, usually when it's close to the top of its trajectory the booster detaches and it starts a cruising phase. The high altitude allows for greater fuel efficiency and speed, in this mode the cruising phase's speed balances around Mach 5 although in some cases a speed of Mach 5.23 has been measured.
When it enters the terminal phase it goes into a dive towards the target envelope, the anti-ship missile version activates it's radar and starts looking for its target at a height of 60km. The usual speed at its terminal phase is Mach 5 and it hits its target from above or at a high slanted angle of attack.
This mode gives it a greater range of 350km and allows the missile to use its speed to the maximum. The downside is that this mode makes it fly above the radar horizon thus allowing defenses the ability to take it out with long range missiles even when there's no over the horizon radar available.
The air launched version of the missile follow a similar scheme. The air launched version lacks a two stage booster. After launch it removes its intake cap using two rockets mounted in the cap and ignites its booster rocket. Depending on the trajectory mode it either goes upwards or downwards.
In both cases the air launched version enjoys greater range to high altitude from which is fired. Normally this increases fuel efficiency from an early start.
In low trajectory mode the booster accelerates the missile to mach 4 and then releases. In a cruising phase the missile begins increasing speed and decreasing altitude with a sustained speed of Mach 5 for most of the flight. After it reaches 14.000m above sea level in keeps a sustained flight until the terminal phase at Mach 4-4,5 and then follows the same pattern as it's ground launched version. However the range of the missile is 350km. Resulting in it receiving a short range stand off missile designation. Although the altitude by which it is launched can allow the target early warning of the missile's launch in some cases.
In high trajectory mode it increases its altitude and follows the same patterns as the ground launched version in this mode. It has a range of 400km.
During flight in both modes for all versions, it's also able to make a series of maneuvers. Which can either serve to put it in the right direction or as a series of evasive maneuvers to increase the difficulty for defenses to intercept the missile.
These evasive maneuver patterns must be preset before launch. It can either choose out of a set series of maneuver patterns or allow it to determine its own maneuvers (which usually are more erratic and random.) In all cases the missile maneuvers towards the target should the its targets position be moved during flight.
Maneuvering does decrease the range of the missile slightly but gets worse especially when the maneuvers are frequent.
There are many different versions of the Nenda-12 cruise missile who vary between type and launch platform. The existing versions are as followed:
A ground launched anti-ship missile deployed from fixed or mobile launchers. A nuclear warhead version exists with the designation: Nenda-12GL AN.
A ground launched land attack version. A nuclear warhead version exists with the designation: Nenda-12GL BN
A ship launched anti-ship missile for use on surface ships. A nuclear warhead version exists with the designation: Nenda-12N AN.
A ship launched land attack version. A nuclear warhead version exists with the designation: Nenda-12N BN.
A submarine launched anti-ship missile for use on submarines like the Tehraani Kora Class SSN. A nuclear warhead version exists with the designation: Nenda-12NS AN.
A submarine launched land attack version. A nuclear warhead version exists with the designation: Nenda-12NS BN.
An air launched anti-ship missile for use on bombers and some larger fighters. A nuclear warhead version exists with the designation: Nenda-12AL AN.
An air launched land attack version. A nuclear warhead version exists with the designation: Nenda-12AL BN.
An air launched anti-radar version. A nuclear warhead version exists with the designation: Nenda-12AL CN.
Posted: Dec 15 2011, 11:01 AM
Most Consistent Desginer (2012)
Member No.: 336
Joined: 25-April 08
While the Munitions forum here does tend to get fewer replies, i'll ask you this. What are you basing the 800 km range figure on?
Posted: Dec 15 2011, 02:54 PM
1% Armaments Designer
Member No.: 1,068
Joined: 23-February 11
If you want to get technical I didn't calculate that range.
More or less I based it on my own estimation on what the missile might be able to reach when fired from an aircraft at altitude and then climb to an higher altitude and continue from that point as described in the write up.
Call it an optimistic guess, as it might very well be less if I'm wrong.
Posted: Dec 16 2011, 02:10 PM
1% Armaments Designer
Member No.: 1,068
Joined: 23-February 11
after some discussions with Yanitaria on IRC I have made some changes to the range and flight altitude.
Posted: Dec 16 2011, 02:35 PM
My tank is umbrella!
Member No.: 401
Joined: 3-June 08
I see no huge issues but I am concerned about the paragraph claiming jamming the missile is "suicide". Home on jam is mainly effective against noise jammers. It is very unlikely a ship would use a on-board noise jammer against a cruise missile, a deception jammer (which will not automatically trigger home on jam) or an expendable off-board noise jammer is far more likely.
Home on jam is a useful feature yes but it's no magic bullet against ECM.
Posted: Dec 16 2011, 04:09 PM
1% Armaments Designer
Member No.: 1,068
Joined: 23-February 11
If you say so. I'll edit it.