I really should change my personal text
- Apr 10, 2013
- Reaction score
TinWing said:The Medway, a JT8D equivalent, was indeed based on the earlier Conway, which more or less was the equivalent of the contemporary JT3D. Of course, the Spey didn't exactly have a commercial competitor from P&W, at least not one that made it to production.
The TF30 was virtually equal to the non-afterburning Spey in power, fuel consumption, & weight - but was slightly larger in diameter (42" vs 38") and length (125" vs 115"-118"). As it was originally designed as a subsonic engine* (like the Spey was), it would have been suitable for similar commercial use.
However, P&W had already created a turbofan version of the J52 (the JTD-8, first run in 1960), which (at 42.5"/123.5") was right at the TF30's diameter and length, and was also a little more powerful at the start (12,250lbf) and a lot more powerful in later versions (21,000lbf with a diameter of 49") than either.
This engine saw a lot of commercial success, as well as powering the SAAB Viggen (with inclusion of an afterburner), and powering ships and land power stations as the FT12.
* For the Douglas FD6 Missileer. It also powered the Vought A-7 Corsair II in the A/B/C variants, before a modified Spey was selected for the A-7D/E versions (TF41, jointly developed and produced by Allison and RR).