OT - SR71 break up .........

That was certainly worth reading .

All those test pilot guys have balls so big I am surprised they can walk. I remember the cockpit recording of a test pilot in one of the passenger planes that got into an unretrievable stall - was it the Ba

1-11? He kept detailing everything they had tried to get out of it, seemingly for ages, calm as you like, until they ran out of air. I think they fitted a stick pusher in it after that to make sure it could never stall again. Then there are the de-icing tests where they have to fly a plane until the ice is heaped on the wings and test the de-icers break it off safely. I hope they get a good pension.

Steve

All jets with the engines mounted at the rear on the fuselage side have a high T tail to keep the elevators out of the engine generated turbulence. This can create a "deep stall" situation if the aircraft enters an extreme nose-up state, the elevators are in dirty air from both the engines and the stalled wings so there is no way to get the nose down into a dive to regain speed and exit the stalled state. In the more conventional layout with the engines on the wings and a low tail a blast of max engine power can create an artificial airflow over the elevators and restore elevator authority.

Such aircraft must be prevented from ever entering this condition both by crew training and by automated system such as stick pushers and fly by wire envelope control. In other respects the rear engine configuration is preferred because the thrust from both engines is close to the aircraft centreline so it is easier to control if one engine fails.

The A-12 and SR-71 development story is well worth reading, as is the 'Skunks Works' and other related material. Always good for a transatlantic crossing!

The other 'forgotten' disaster was the XB-70 Valkyrie accident, when one of the camera/escort planes got into a wingtip vortex and ended up hitting the plane and causing its total loss. The escape of one of the pilots is an amazing tale too.

Another book that we bought over at the USAF museum, the XB-70 development story is fascinating stuff, especially bearing in mind when it was all taking place. The accident is covered in great detail, and the subsequent enquiry.

There is one remaining plane extant, in the museum itself.

It's a bit dog-eared as it stood outside for a long time before the new museum buildings were in place, but it's a nice aircaft to walk around.

Peter

-- Peter A Forbes Prepair Ltd, Rushden, UK snipped-for-privacy@easynet.co.uk

The XB-70 paperclip story is funnier.

"Houston, we have a problem - no undercarriage"

' Check fuse #1234'

'It's knackered"

'Got a spare?'

"No"

"Got some flight notes though, and they're fastened together with a paperclip...."