Following Hesham's example, I've been exploring Flight's archives. German civil projects in a June 1963 edition caught my eye. Do others have further info on the Siebelwerke SIAT 311?
According to Flight, the SIAT 311A twin-jet, a "straight-wing, 17-seat 18,740lb airliner with [5180 lb st] Lycoming PLF1B-2 turbofans [*] hung on the rear fuselage".
http://www.flightglobal.com/pdfarchive/view/1963/1963%20-%200936.html
Aeroknow has a magazine listing for the Siebel-SIAT 311, listing it as a 20 pass STOL jet. Air Progress Oct/Nov 63
http://www.aeroknow.com/ADImisc/Germ3-ADI.htm
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* According to Jane's, the PLF1 was a geared turbofan based on the "T55-L-5 turboshaft with an added Low-Pressure (LP) turbine and central shaft which, via a speed-reducing gearbox, drove a completely new front fan. Via the more powerful PLF1C-1, the design was refined into the ALF502". This engine seems to have been very popular with German designers at the time, also showing up on the early VFW-614.
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