Sir - In view of the detail on operating and support costs published since the withdrawal from service of the Lockheed SR-71, it is surprising to read that this aircraft is to be revived in the US Air Force inventory (Flight International, 18-24 January, P16).
It has been widely assumed by most observers that the SR-71's role would be taken over by its replacement, the Aurora, and that the retirement of the SR-71 was an indication that the replacement programme had progressed to the point where this decision could be taken.
It would seem that the retirement decision was premature and that the Aurora is proving more difficult to develop than expected.
This would not be surprising if the speculation on the power plant is correct. An update on the SR-71's airframe and avionics is relatively straightforward; development of a mixed-cycle power plant is not, particularly as such an engine would have limited application in the immediate future.
D F NEWLAND
Watford, Hertfordshire, UK
Source: Flight International