Raytheon AGM-289 Coral Snake

     Notes: For some reason, this did not occur to me until years after I came up with the R-5D Aurora hypersonic reconnaissance/strike aircraft: If the R-5D was going to be conducting a surprise nuclear strike against a North Korean division in the Twilight War, it would need to have an even faster weapon to fire to conduct that strike. That is the reason for this entry – something for the R-5D to use in its strike, and potentially planned for other strikes.  Thus, the Coral Snake ASM.

     Twilight 2000 Notes: As war clouds loomed over the world in the early 1990s, it was thought that the Aurora aircraft could, with its modularity, be repurposed on occasion as a strike aircraft for use against strategic targets where conventional bombers or strategic missiles would not be appropriate or advisable.  In addition, the Aurora could also be used to strike targets where further a rapid response time would be needed and pinpoint accuracy would be warranted.  However, no such weapon was at that time in the US inventory. In January of 1993, Raytheon was secretly contracted by DARPA and the US Air Force to come up with such a weapon.  The new weapon would need to be even faster than the Mach 5+ the R-5D was capable of, have a range enough to keep the R-5D reasonably out of danger, and be able to carry enough of a warhead to make the strike worth it.  Ideally, it would also need to be capable of bunker busting, able to penetrate through up to 25 meters of reinforced concreate and earth with a conventional warhead, or carry a decent throw weight of nuclear warhead.  Raytheon felt that this was too much for the DoD to ask, but gave it their best shot, with excellent results, producing the AGM-289 in record time for such a weapon – the XAGM-289 prototypes were flying by July of 1995, with LRIP (there was never any full-rate production) beginning about a year later.  The prototypes were noted for their elaborate paint schemes, reflecting the color pattern of the snake from which their name is drawn.

     Raytheon began with a modified Phoenix missile, but quickly found that the Phoenix’s airframe, intended for use as an air-to-air missile, could not carry a large enough warhead for the task.  Raytheon then enlarged the Phoenix, increasing its size by over 50%.  This also allowed for the fitting of a new high-impulse rocket motor which accelerated the Coral Snake to Mach 7 in less than a minute when dropped from a Mach 5-flying Aurora aircraft.  The high speed allowed the Coral Snake a satisfyingly long range when fired from an R-5D at speed. (Attempts to mate the Coral Snake with other aircraft, such as the B-52, B-1 and B-2 did not lead to as dramatic results, with the AGM-289 able to accelerate to only Mach 4.5 when fired from such an aircraft, and the AGM-289 became an Aurora-only weapon until late in the War.)  As the airfoils were not enough to give the missile enough control in flight, thrusters were added near the tail to give the missile more control authority.

     The carriage of an AGM-289 required a slight modification to the R-5D’s weapon bays due to the weapon’s large size and the need to kick the missile into the slipstream and away from the aircraft quickly.  In addition, the use of Coral Snakes required the replacement of some of the R-5D’s reconnaissance fit with fire control avionics.

     Warheads initially tested were conventional, and primarily HE warheads with nose of the missile tipped by a thick tungsten cap for additional penetration.  These proved to be effective enough to meet and even exceed the original DoD specifications for penetration.  Initial guidance was to be by GPS, but as satellites began to fall, inertial positioning was fitted with a TERCOM kicker.  This of course required the pilot of the Aurora to fix the position of the target and link it to the AGM-289 before launch, something which required about 15 seconds of minimal maneuvering.  However, a nuclear warhead was always considered for the Coral Snake, and one modified from that of the B-61 bomb was fitted onto six Coral Snakes.

     Perhaps the best known, and most controversial, use of a Coral Snake from an Aurora aircraft was the November 1997 nuclear strike on a North Korean division that was closing in on Allied forces in North Korea.  The strike was until the 2030s known as “the nuclear strike from nowhere”, as no side had any launch indications from any weapon system or aircraft carrying a nuclear warhead in theater, and no one was going to send a relatively inaccurate missile from out of theater.  Nonetheless, the Coral Snake scored an almost center-mass bullseye on the North Korean division in question, with a warhead programmed for 100 kilotons of yield.  This saved the Allied Forces’ bacon for a while, but the use of a tremendously expensive and irreplaceable asset like an R-5D was discussed among military leaders until it didn’t matter anymore.

*The speed is when fired from an R-5D at speed/subsonic launch.