Contributor - UK

David Donald

Rafael’s Derby active-radar air-to-air missile has been in service since 1998 and is in operational service with six customers. To keep the missile capable of meeting current and future threats, Rafael has undertaken two major upgrades that not only improve seeker performance, but greatly increased range capability.
As a first step Rafael (Static A8) developed the I-Derby with an all-new seeker head and guidance package. The package is more flexible than the previous unit, with a better ability to control the waveform. Its electronic counter-countermeasures performance is improved, a necessary step to match and stay ahead of advances in electronic warfare systems. At the same time, the seeker retains the “lock-on before launch” function that gives the Derby a short-range “fire and forget” capability, in which the missile’s seeker head can be slaved to the pilot’s helmet display for close-in dogfighting.
I-Derby’s seeker/guidance package employs solid-state technology so that physical size and weight has been reduced. At the same time Rafael replaced the large proximity fuse fitted to the original missile with a much smaller RF-based fuse located at the base of the seeker’s radome.
Taken together, these enhancements have freed up considerable volume internally for the fitment of a larger propulsion system, resulting in the I-Derby ER. Rather than just increase the amount of propellant carried, Rafael opted for a dual-pulse motor. The initial launch pulse is similar to that of the original Derby, but a second pulse can now be fired at a time dictated by the missile’s flight control system, which detects when the weapon is running out of energy. Firing the second pulse is normally undertaken shortly before intercept, greatly increasing the missile’s maneuvering energy in the end-game as a means of expanding its no-escape zone. 
At the same time, the I-Derby ER’s range is increased to more than 60 miles, placing it into the long-range category and allowing it to better exploit the greater capabilities being introduced by modern fighter radars. The missile is also completely interchangeable with the Derby used in Rafael’s Spyder-SR ground-based air defense system. Theoretically, I-Derby ER could also be adapted with a booster motor as used by the current Spyder-MR system, although Rafael sees little operational need for such a long-ranged system.
I-Derby ER was first unveiled at Aero India in February. Rafael is switching production over to the new version and, while the company remains coy about development status, insists that it will be available to customers within a typical missile order-to-delivery period of around two years. The company has identified at least five potential customers who are looking for a 60-mile long-range air-to-air missile.

Rafael Unveils Long-range Derby Missile

Rafael has developed its Derby active-radar air-to-air missile with improved guidance and longer range.

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