Nimrod 'The Mighty Hunter'

He was a mighty hunter before the Lord; therefore it is said, "Like Nimrod the mighty hunter before the Lord." Genesis 10:9

The Nimrod was to be based upon the Comet 4C; however, the overall fuselage length was to be reduced by six feet six inches, similar to that of the earlier Comet 4. The obvious external change was the addition of a large, under slung pannier, which protruded forward of the nose section, and ran rearwards approximately three-quarters the length of the fuselage. This was an un-pressurised section designed to accommodate the weapons bay.

The initial design for the pannier was somewhat different than the version eventually incorporated, and included a crew position for a forward lookout, which could only be manned during un-pressurised flight. In order to offset the reduction in directional stability resulting from the increased keel area associated with the pannier, a dorsal fin was later added to the existing fin. Finally, an 'upturned canoe shape' fairing was fitted to the top of the fin in order to house an Electronic Surveillance Measures antennae.

Other external features which required redesign included the sizeable engine intakes required of the Rolls Royce Spey turbofan engines. These, coupled with the larger exhaust section, necessitated some alteration to the wing centre-section. All but 11 of the original Comet fuselage windows were removed and three, bubble-type, observation windows were added towards the forward fuselage section; the flight deck windows were altered to afford flight deck crew members a better visual lookout essential for maritime, low level flying.

Although the new aircraft made use of an existing airframe which included many of the original systems, there still remained much in the way of design and development. The introduction of the larger Rolls Royce Spey engines and a new electrical generating system, two of many other modifications, had to be accommodated and thoroughly investigated before installation and flight trials could begin.

Minimal structural testing was required; however, tests were required on the radome, fuselage frames, crew seats and bomb bay stores carriers. It was also necessary to strengthen the undercarriage in order to support the increased operating weight of the Nimrod as compared with the Comet; this item too, had to be fatigue tested. A Comet nose fuselage section was modified to incorporate the larger flight deck windows and the integrity of the new design tested in a water tank.

Wind tunnel tests were conducted on the new fuselage shape and the redesigned engine intakes. Rolls Royce conducted flow distribution tests on full scale intakes, and engine test bed runs, amounting to more than 1200 hours, were undertaken. An existing electrical test rig facility at the Hawker Siddeley Woodford factory was modified to prove the new electrical generating system. Tests began in April 1966.