Aviation Historian 6
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R.Simpson - Elegant Imperfection
The competition - Grumman’s Dart-powered Gulfstream I made its first flight in August 1958, the type paving the way for a highly successful series of executive jets. This extremely attractive example was exhibited at the Paris Air Salon at Le Bourget in 1961.
Also in the executive park at the 1961 Paris show was the 840 prototype, by now painted in an understated but stylish bare-metal, blue and white scheme, with the Potez emblem on the forward fuselage. The company was keen to promote the 840 as ideal for internal services linking provincial centres with major international airlines.
The first of the two Potez 842s built with uprated Astazou XII engines, F-BNAN, which went on to serve with French training organisation SFA during 1966-76, after which it was acquired by the Musee de l'Air at Le Bourget, where it still resides.
The first Potez 840 prototype, F-WJSH, in bare metal before flight vibration tests at the Potez-Air Fouga factory at Toulouse-Blagnac in 1961. The 840 was designed by Robert Castello, who had worked with Pierre Mauboussin on pre- and post-war Fouga designs since the mid-1980s, having joined the company from Dewoitine.
Another of Jean Dieuzaide’s atmospheric promotional photographs of the first prototype Potez 840. The company had bet the farm on the graceful transport, but in the crowded civil aircraft market of the 1960s orders were not forthcoming and the remnants of Potez were absorbed into Sud Aviation in 1967.
The second 840, F-WJSU, during a photographic flight. A number of modifications were incorporated on the second airframe; the windscreen shape was altered and an extra side-window was added to meet American FAA requirements. The aircraft’s gross weight was also increased to 18,700 lb and fuel capacity raised to 366 gal.
One of a sequence of superb publicity photographs of the Potez 840 taken by renowned French photo-journalist Jean Dieuzaide, who made his reputation capturing magnificent images of the Caravelle and Concorde. In this photograph of the 840 prototype Dieuzaide accentuates the slender, graceful nacelles of the aircraft’s Turbomeca Astazou turboprops.
The first Potez 841, F-WLKR, fitted with four 578 shp United Aircraft of Canada PT6A-6 (PT6A-22 ???) turboprop engines at Toulouse-Blagnac in January 1965, a few weeks after its first flight on December 22. The tiptanks have been added and the aircraft is in the bare metal, pale blue and white colour scheme of German distributor Aero Dienst, with which it was re-registered D-CAER.
Represented in its intended final production configuration, with 33 gal tiptanks and Astazous, th 840 was illustrated in this reference drawing as one of a series which used a common key, hence the non-sequential numbering system in the key.
Cutaway key: 1 Pressure bulkheads 2 Passenger door 3 Crew door 6 Emergency window or hatch 7 Cargo doors 8 Fixed toilet 9 Electronics equipment 11 Main undercarriage well 12 Nosewheel well 13 Reverse-pitch propellers 15 Integral fuel tanks 28 Intake to air conditioning 29 Electrical de-icing 37 Captain 38 First Officer 44 Gravity fuel filler 55 VHF radio equipment 56 VOR radio equipment 58 ADF equipment 61 ILS equipment 64 Hydraulic equipment 65 Air-conditioning equipment 73 Taxying lamp 75 Anti-collision beacon 95 Compass detector unit 99 Engine access 134 Floor loading (52 lb/ft2 min) 140 Hot-air de-icing
The two proposed cabin configurations for the 840, with the 16-seat standard layout ABOVE and the high-density arrangement for 24 passengers BELOW.