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
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 at the bottom
(compiled by Peter W. Dance, Air-Britain).