Never seen this before or since on any aircraft, anyone know the reason (s) why Lockheed designed it this way ?
I believe that I was told why it was designed that way in initial school, but for the life of me I cannot remember why. Sorry.
There were some other
different designed systems on the Jetstar as well. There was a 'Mach trim' system separate from the auto-pilot system that you turned on before takeoff and off on shut down, I don't why that was either. Also, I don't believe that there was a standard door/stair design either.
Now the most interesting design concept, well to me anyway, was the leading slats. They had to deploy for takeoff, but if they failed to extend on landing there was no speed penalty. If V-Ref was 115 kts with slats, it was still 115 kts with no slats. Even with the slats the Jetstar loved runways. Same with the speed brake under the tail of the aircraft, dang near useless.
However, I loved flying the Jetstar. One of the nicest flying aircraft I ever had the pleasure to fly.