Former RB-25H 43-4106 was transferred on loan to the Bendix Aviation Corporation of Detroit, Michigan, in August 1951 as N5548N and employed on a wide variety of test-bed work until it was disposed of in 1967. ‘Four-Eight November’ is illustrated with a centre fuselage-mounted jockey wheel for unknown purposes. Initially the aircraft flew in an overall natural metal scheme, later taking on company house colours. N5548N flies today in 1st ACG markings as ‘Barbie III’ operating out of Aurora, Illinois.

Detail view of a most unusual undercarriage tested on N5548N. The solid rubber tyres are most apparent, but the rear view (inset) reveals the astonishing off-centre axle arrangement. What can readers tell us of this experiment?

View of N5548N showing the installation of over-sized tyres - note the white calibration markings on the port mainwheel.

Extensive test instrumentation installed in the rear fuselage of N5548N. The aircraft flew autopilot development sorties as well as helping to test landing gear and anti-skid devices.

Detail of N5548N’s flightdeck.

Also used by Bendix for test work was B-25J N69345 (previous 44-8835). From June 1946 it was with the Eclipse Pioneer Division of Bendix at Teterboro, New Jersey, testing the PB-20 automatic control system, as illustrated. ‘Three-Four-Fiver’ moved through two other Bendix divisions before being disposed of in 1972. Currently registered as N5672V, this B-25 is under restoration by Aero Trader at Chino, California.

At one time ‘Hap’ Arnold’s personal aircraft, Bendix took on VB-25J N3184G (ex 44-29945) in 1963 as a VIP transport and installed an airstair door, among other modifications. It was sold in 1968, moving on to Bolivia as CP-970 and was destroyed in a crash there in June 1976.