History Brief, by Johan Visschedijk December 17, 2003

On Mark Marksman

On Mark Engineering Company was set up in 1954 to modify, repair and overhaul aircraft, including the Douglas B-26 Invader. After some time the company considered converting the B-26 bomber into a high-speed civil executive transport. A Supplementary Type Certificate was issued in January 1961 with the first delivered the following month. A major redesign was the removal of the rear wing spar portion that passed through the cabin, this being replaced by a steel circumferential beam; this led to a considerable increase in cabin length. Further the fuselage was redesigned to provide headroom of 6 ft 1 in (1.85 m) throughout and with the increased pressure differential the cabin altitude of 6,800 ft (2,075 m) could be maintained at a cruising altitude of 20,000 ft (6,100 m). The Marksman was configured in a six to eight passenger layout, in two standard cabin furnishings. The "Administrator" layout had two pairs of armchair seats facing each other with a folding table between, and a three-seat divan with the "Director" having six armchairs in various layouts. In both versions a bar, a beverage cabinet and a tape recorder were installed. The redesigned cockpit provided increased headroom and a better field of view for the two pilots who were seated in state of the art chairs. In the starboard side of the cabin an electro-hydraulically operated airstair door was installed. The nose section was lengthened by 8 ft 7 in (2.61 m) to provide room for the weather radar and 1,000 lb (454 kg) additional baggage could be stowed in this area. Only eight aircraft were converted to Marksman, see the list further down, compiled by Peter W. Dance, Air-Britain. Marksman engine test bed Johan Visschedijk Collection

Models

Marketeer: Marksman A: Marksman B: Marksman C: unpressurized conversion of B-26, two 2,100 hp R-2800-75/79 or R-2800-CB16 pressurized conversion of B-26, two 2,100 hp R-2800-83AM3 as Marksman A, two 165 US gal (622 l) wing tip tanks, two R-2800-83AM-4A as Marksman B, two 2,500 hp R-2800-83AM-CB-16/17

Marksman (c/n, s/n, registrations, * indicating occurrence of conversion)

6934, 41-39221, N9636C, N3035S * N256H, N26GT 18607, 43-22416, N1394N * N100Y, N140Y, N190Y, N40XY 27694, 44-34415, N5002X * N900V, N46598 27805, 44-34526, N9178Z * N827W, CF-OFO, N551EH, N400V, N7977, N26AB 27846, 44-34567, N9412Z * ZS-CVD 28040, 44-34761, N67158 * N400E, N60XY, N60XX 28977, 44-35698, N5001X * N800V, N58071, N67623 29149, 44-35870, N1471V * N320, N99426

Specifications (Marksman C)

Type: Engine: Span: Length: Height: Wing area: Empty weight: Max T/O weight: Max speed: Max climb: Ceiling:: Range: Six to eight passenger transport aircraft Two Pratt & Whitney R-2800-83AM-CB-16/17 Double Wasp radial engines 71 ft 6 in (21.79 m) 53 ft 10 in (16.40 m) 18 ft 6 in (5.64 m) 540 sq.ft (50.17 sq.m) 25,000 lb (11,340 kg) 35,000 lb (15,876 kg) 365 mph (587 km/h) at 23,000 ft (7,010 m) 1,700 ft (518 m)/min at sea level and 32,000 lb (14,515 kg) 25,000 ft (7,620 m) 2,500 mls (4,023 km)