Spey pedigree.
RAF Requirement for Canberra Replacement was issued 9/57. RR schemed RB.140, then derived RB.141/142 Medway. Bristol Olympus won TSR.2, but Medway was design baseline for DH bid for BEAC's medium haul Reqt, until they reduced its size. RR scaled down, 14,000lb to 10,000 as Spey, ordered for DH.121 Trident, 1/3/58. Medway continued to be schemed in parallel and was design baseline for Boeing 727, mid-59 almost to its 30/11/60 launch. Spey/BAC-111 followed, launched by Laker, 5/61. Medway continued to be offered, selected for RAF HS681 V/STOL transport, 9/63 till cancellation 2/65. SAAB had chosen it for Viggen, but then moved to P&W JT8D.
RN had been lumbered with P.1154, 18/2/63 with single BS.100, common with RAF: what RN had decided they wanted, as early as 1960, was reheated Spey-in-F-4B. Not J79 because Phantoms would first be deployed on Ark Royal, Eagle and Victorious (eventually on aspirant CVA-01/03). The calculation was the bolter case, where half-second slam reheat response was seen as available on Spey, not on J79.(RN had secured dry Spey, ordered for Buccaneer S.2, 1/62). RN was allowed to buy F-4K/Spey and quit P.1154, 2/64.
When P.1154(RAF) was cancelled 2/65, RAF wanted straight F-4D/J79. Roy Jenkins, Minister of Aviation, knowing TSR.2 was also for the chop (4/65), persuaded Ministers that something must be preserved for UK industry: Spey-for-RAF F-4M was agreed (as was to be Harrier, which RAF had not then wanted; so was MR Comet-with dry Spey: Nimrod). As offset for F-111K, US DoD put Spey as TF-41 into later A-7s; many other applications followed (inc. a licence to Xian Red Flag, 12/75 for Harbin H-7).
In 1966 RR was cascading Speys, whereas Bristol Siddeley was scratching for business, making a JV with P&W to join JT9D: that would threaten RB211 so RR bought BSEL and killed UK-in-JT9D. They could not have afforded that without Spey business.
Last edited by tornadoken; 5th Jun 2019 at 10:39.