I have a slight correction to Mr Grantham's comments (Flight International, 24 February-1 March) on my letter about the Lockheed Martin Joint Strike Fighter (Flight International, 10-16 February). The critical flight-mode transition, requiring validation in a representative airframe, should have been described as that between partly jet-borne and fully wing-borne flight. This does not alter my assertion that the fly-off was inconclusive about the short take-off vertical landing capability.
Now that testing is in full swing, perhaps we will read more about the lift fan system with its drive, cooling, thrust vectoring, controls and closure panels. These are interesting successors to the separate lift engines used in the VFW-Fokker VAK 191B and Yakovlev Yak-141.
As for the 20-year gestation of the Eurofighter Typhoon, I also attribute a major part of the blame to the users and their purchasing agencies. The end of the Cold War, asymmetric conflicts in far-off places, and rapid technical and industrial changes have left the requirements planning in tatters.
In the UK, the time spent at the front-end of projects is normally more than adequate, but it is misspent on window shopping and debate, rather than on serious preliminary research into technology, tactics, requirements and concepts. After the dithering, everything has to be done with unseemly haste, greatly increasing exposure to risk. With the F-35B, it looks as if the demonstration phase was too short - but the result is the same.
Richard Lloyd Coventry, UK
Source: Flight International
