Grisha's Missile \xc2\xabShoot-Off\xc2\xbb

The claimed development or indeed existence of the 'R-74-PD' two stage hybrid BVR combat missile cannot be verified easily via open sources since there have been no disclosures to date in the Russian press. The evidence is at best 'anecdotal'. Air Power Australia will therefore not speculate on whether this missile exists, is in development, or is merely a boastful claim on the part of a Russian missile industry executive. What Air Power Australia can do is comment on the technical feasibility of such a weapon and its likely performance in an operational environment.

As Colonel Medved points out, Russian industry has used two stage missile designs before for air launched applications. The 3M54AE air launched variant of the Sizzler ASCM is an example, with a Mach 3 rocket propelled terminal stage mated to a subsonic cruise missile airframe as a midcourse stage. Vympel have also experimented with reverse firing variants of the R-73, specifically the two stage R-73R equipped with a booster pack to cancel the momentum imparted by the launching aircraft when firing the missile backward. Therefore the experience required to produce a two stage missile of this ilk exists in the industry, and specific experience exists on mating the R-73 airframe to a booster stage.

The long burn variants of the R-27 Alamo have a dual pulse motor and a range of different seeker heads, and are credited with a range of around 70 nautical miles against a closing target, using the legacy analogue seeker package. Range performance for the optimised digital 9B1103K series seeker has not been disclosed. This missile is widely deployed with Russian units and has been exported in the semi-active radar homing and heatseeking variants. As a result there is a large warstock available and the missile remains in production.

The R-74E is the production designation of the new K-74E "digital Archer" with a redesigned seeker package, and it is the most lethal short range missile developed by Russian industry to date. It employs a high off-boresight capability gimballed seeker and thrust vectoring to provide a very high G load capability and thus high lethality in close combat. To date the missile has only been shown in the heatseeking variant equipped with the MK-80M series scanning two colour seeker, but a new MK-2000 gimballed seeker was in development. Agat recently developed the 9B1103K-150 which is a repackaged "small bore' variant of the R-77 AMRAAMski's 9B1348 series active radar seeker, sized for the Archer airframe. The seeker includes Fibre Optic Gyro (FOG) inertial unit, a digital processor (using the US TMS320 chip in later variants), and a planar array monopulse antenna.

All of the technology to build the 'R-74-PD' therefore is available. The question is how would such a missile have been integrated, and what is its likely performance if it indeed exists?

The long burn Alamo is viable as a booster stage to carry a terminal kill stage into the acquisition box of a target. The missile has a launch weight of around 750 to 780 lb in the R-27ER1/ET2 variants, and uses the "butterfly" canard surfaces for control, with fixed tail surfaces. A boost stage derivative would have to retain some shortened configuration of the control section as this is required to mount the midcourse control surfaces and actuators, the main battery, the midcourse guidance computer and the datalink receiver. How long this section is will depend on the design employed and whether newer or legacy components are used. This configuration would allow the launch aircraft to shoot this missile off the standard R-27 AKU-470 ejection unit/APU-470 launch unit using standard umbilicals and existing radar software for midcourse steering commands.

Interfacing any variant of the Archer to such a boost stage will require some arrangement to provide structural stiffness and a protected interface to the Archer's umbilical port to provide an emulation of the aircraft interface, including thermoelectric cooler drive for the infrared seeker variants. The simplest arrangement is likely to be a strongback rail over the R-74 airframe which is joined to an adaptor. This allows the the R-74 to be fired as if off the standard P-72-1D/P-72-1DB2 launch rail. The overall length of this configuration will depend on the length of the midcourse section and adaptor sections, but is not significantly greater than the larger Alamo long burn variants. Other configurations are also possible.

The integration of such a weapon could follow a different track. The cheapest configuration for mass production would see a 'smart terminal stage' and 'dumb midcourse' stage, with the IMU and midcourse control software in the R-74 stage, and the R-27 adaptor volume used only for control actuators, battery and datalink receiver, with the umbilical dedicated to controlling the midcourse stage, and carry datalink and prelaunch aircraft commands to the terminal stage guidance computer. This approach is more reliable since only one control computer and software OFP is required.

Performance presents some interesting questions. The heaviest Alamo variants are claimed to have 70 nautical miles of F-pole range, but a digital seeker with a more refined boost-glide trajectory algorithm could add a useful percentage to the range of the basic missile. The later R-73 Archer variants are credited with a range of 21 nautical miles, but this is assuming a launch from a transonic fighter rail, where the missile's motor must impart the energy to get to the peak supersonic speed of the missile.

A two stage weapon of the kind discussed by Colonel Medved would launch from a burned out gliding R-27 midcourse vehicle likely to be travelling at Mach 2-3 and with an altitude advantage over the target. Other than the initial impulse required to cleanly separate the terminal stage from the midcourse stage, the launch speed of the R-74 stage would be similar to its design cruise speed. This begs the question of what is not being said here. The optimal rocket motor burn profile for a boosted R-74 Archer would be very different from the standard missile, which has a high impulse but very short burn of mere seconds.

The optimal rocket motor burn profile for a boosted R-74 is a slow burn to impart enough thrust to overcome drag at the missile's cruise speed, but sustain that thrust for as long as possible to maximise the missile's endgame G load capability, and make use of the thrust vectoring capability of the airframe. In a sense this is the model pursued by the Israelis with the Python 4/5 airframes, designed to sustain maximum G capability until target impact.

It is clear that such a boosted R-74 Archer variant would achieve 100 nautical mile class range, without a ramjet, using existing technology. The endgame lethality of the weapon would also be high, and likely much greater than the 'standard' Archer variants especially if the motor burn was reprofiled.

Clearly there are many uncertainties remaining as to the design of such a weapon, but several things are abundantly clear:

The missile is technically feasible.
The missile would have competitive range against the MBDA Meteor and much better range than dual pulse AIM-120 variants.
The missile would have higher endgame G capability and lethality compared to the standard Archer.
The missile would not be significantly heavier than the baseline long burn Alamos, permitting similar warloads on the Flanker.
The missile could be introduced very rapidly and with very modest development risk.

For comparison, the US is currently developing the NCADE, which uses a two stage arrangement packaged into the AMRAAM form factor, with an AIM-9X seeker and high energy hydroxylammonium nitrate propellant second stage motor. While an air to air derivative of the NCADE would provide excellent range performance compared to baseline AMRAAM models, the terminal stage is built for manoeuvre in the upper stratosphere and is not optimised for maximum tropospheric G performance. A boosted R-74 Archer variant would be far better adapted to killing agile fighter type targets as it is an optimised design. It is certain that the Russian industry is looking at the NCADE program very carefully.

Raytheon's NCADE is a two stage Anti Ballistic Missile boost phase interceptor derived from the AIM-120 AMRAAM. The first stage is an AMRAAM motor, the second stage sustainer uses a high energy liquid propellant hydroxylammonium nitrate motor, with a hydroxylammonium nitrate four nozzle control thruster system (Raytheon images).

In short, if a program to develop an 'R-74-PD' exists, the BVR missile combat game is yet again about to become more complicated and more lethal.