Israel has had the unenviable experience of being surrounded by much larger neighbours most of whom, since 1948, have had an openly declared intention to destroy the Jewish state. Since 1948, the Israelis have fought a number of wars in order to initially survive, and later to secure their borders. In every single instance, air superiority proved to be the decisive factor in achieving both tactical and strategic victories on the battlefield. Current Israeli military doctrine accords the maintenance of air superiority the highest priority.
One of the consequences of Israel's military experience since the sixties has been to develop a strong domestic capability to design and manufacture modern military equipment and weapons. Indeed their experience in the sixties, when France unilaterally withdrew all support for French equipment in Israeli service, and more recently US dithering over the supply of aircraft has led the Israelis to source as many "consumables" as possible from domestic manufacture. Since the WVR AAM is such a critical component of the air superiority game, the Israelis have been building their own since the early sixties.
The first Israeli AAM to see production was the Rafael Shafrir (Dragonfly) I in the early sixties, a contemporary of the AIM-9B. It was followed by the improved Shafrir II, in production between 1968 and 1980 and credited with over 100 kills, mainly during the 1973 Yom Kippur war. The third generation Python 3, a contemporary of the AIM-9L/M, was introduced during the late seventies and is credited with over 35 Syrian aircraft kills during the Bekaa Valley air battle in 1982. Both the Shafrir and the Python 3 utilise a similar aerodynamic and control configuration to the AIM-9, but are unique missile designs.
The fourth generation Python 4 was developed during the late eighties and early nineties, deploying on Israeli F-15 and F-16 fighters during the early nineties. The missile and its associated Elbit DASH (Display And Sight Helmet) third generation HMS were developed specifically to outperform the Soviet Archer/HMS and MiG-29, both of which deployed in the Middle East by the early nineties.
The Python 4 is a true fourth generation missile, designed from the ground up for the demanding requirements of this style of air combat. It employs an all aspect gimballed seeker designed for large off boresight acquisition and tracking angles, and a high tracking rate. It also employs a new powerplant, and unique aerodynamics specifically optimised for high agility.
The intent of the designers was to produce a missile which can not only be shot from a wider range of angles than earlier missiles, but which can also maintain track on a highly manoeuvrable high G target engaged during the merge or opening phase of an engagement. A passing target on a reciprocal heading can be engaged in most of the forward hemisphere, if the Python fails its first opportunity to hit, it will maintain track on the target and continue a tail chase geometry pursuit on a reciprocal heading to the launch aircraft, running down the target for a tail-aspect hit. The missile is claimed to have sufficient turning performance to defeat high G evasive manoeuvre by any existing fighter aircraft. Existing ACM experience with the missile suggests a typical engagement duration of much less than 30 seconds.
This capability was achieved by carefully optimising seeker, aerodynamic and powerplant performance.
The seeker was incorrectly reported by US sources to be a cooled two colour rotating reticle design, Israeli sources will only acknowledge that the missile usesa multiple detector array seeker, which has an IRCCM (ie IR ECCM) capability and the ability to reject background IR radiation. Typical two colour seekers (eg FIM-92C Stinger) use an Argon cooled InSb 4 micron IR detector and a Si or GaAs UV detector. Valid aircraft targets have a low UV signature and a high IR signature and this enables the Stinger to easily reject spurious targets such as flares. The Python 4 seeker has been credited with significantly better acquisition range than that of the AIM-9M, which is consistent with the sensitivity improvement produced by a multiple element seeker.
The Python 4 is known to employ digital signal processing techniques in the seeker, as well as a microprocessor based digital flight control system. The use of DSP (Digital Signal Processing) techniques will provide the seeker with better acquisition range than analogue seekers by exploiting the multiple detector elements to full advantage, as well as providing further IRCCM capability and the ability to intelligently manage fluctuating target signatures. A digital flight control system will allow the missile to optimise its flight control laws for the regime of flight, while also selectively choosing the most suitable homing algorithm parameters for the geometry of the engagement. The Python 4 missile employs a unique tailored proportional navigation homing algorithm. As a result of these design features, the Python 4 seeker is credited with the capability to engage and track targets throughout most of the forward hemisphere (the exact figure has not been disclosed, UK sources suggest in excess of 60 degrees off-boresight capability), with a high but undisclosed tracking rate.
The missile employs a blast fragmentation warhead which is triggered by an active laser proximity fuse with a backup impact fuse, a design feature in common in the AIM-9, but different from the Archer which employs a radio proximity fuse. The warhead size has not been disclosed.
The Python 4 employs a 6 in diameter rocket motor, a feature it shares with the Archer and the ASRAAM. The long burn motor has a tailored thrust profile to achieve optimal acceleration for close-in closing engagements and high energy for terminal phase homing or end-game engagement. Thrust vectoring is not employed, the missile instead utilises aerodynamic design to achieve a high turn rate throughout the its flight envelope.
The aerodynamic design of the Python is by any standard the most complex in any existing AAM, and is evidently intended to provide the best possible lift throughout the flight profile of the weapon. A cruciform fixed canard is mounted on the nose to stabilise high angle of attack airflow over the cruciform canard control surfaces, which are used for pitch and yaw control, a technique used by a number of existing WVR AAMs. Roll control is achieved by a small pair of "paddle" vanes aft of the controls. The missile employs highly swept strakes along the fuselage which are intended to improve airflow characteristics over the tail surfaces. The swept tail surfaces are designed to swivel about the fuselage, this is designed to minimise lift induced rolling moments at high angles of attack in high G turns.
The combination of a long burn motor and complex aerodynamic design will provide the Python 4 with a high sustained turn rate at all speeds, and this will in turn translate into an ability to follow a high G target throughout any manoeuvre. The missile is credited with much better range performance than the AIM-9M, and better maximum G capability than any existing AAM.
The Python 4 is compatible with all standard AIM-9 capable launchers, and has been tested and cleared for use on the F-15, F-16, F/A-18 and F-5. The only integration requirement for the basic missile is the replacement of the launcher internal electronic unit with a Python capable design, which retains compatibility with the AIM-9. To fully exploit the missile's capability, a Helmet Mounted Sight is required, which will necessitate the fitting of cockpit transducers and supporting electronics. The DASH HMS supports either an analogue or digital interface. Aircraft such as the F/A-18 will also require some changes to the fire control software, to enable selection of the HMS or radar for missile boresight control. The F/A-18 could carry up to six rounds on wingtip and pylon stations.
The Python 4 is currently being bid for the AIR 5400 requirement, and the RAAF have acknowledged that captive carry tests were flown by ARDU late last year. No further details have been disclosed at this time. |
