PROFILPELAJAR.COM

MB-4
Role	Mail plane
National origin	United States of America
Manufacturer	Thomas-Morse Aircraft
First flight	1920
Number built	at least 2
Developed from	Thomas-Morse MB-3

The Thomas-Morse MB-4 was a prototype American mailplane of the 1920s. It was of unusual design, being a biplane with twin fuselages housing the crew of two and a central nacelle which carried the aircraft's twin engines in a push-pull configuration.

Design and development

The MB-4 was designed to meet a June 1919 specification from the United States Post Office Department for a two- or three-engined mailplane, required to carry 1,500 lb (682 kg) of mail on a single engine.^[1] Thomas-Morse chose to use as much as possible of its existing Thomas-Morse MB-3 fighter in order to reduce costs, using two engineless MB-3 fuselages to carry the crew and cargo, with the pilot in a cockpit in the nose of the port fuselage and the co-pilot/mechanic in a similar cockpit in the nose of the starboard fuselage, while cargo was carried behind the crew in each fuselage. Two 300 hp (224 kW) Wright-Hisso H V8 engines were mounted in a central nacelle between the two main fuselages in a push-pull configuration, with fuel tanks mounted between the engines.^[1]^[2]^[3]

The MB-4's three-bay biplane wings were all new, with ailerons on the upper wing.^[3] It had a conventional tailwheel undercarriage and had two separate tail assemblies, which were standard MB-3 empennages. Dual controls were fitted, with the pilot able to disconnect the co-pilot's controls, but there were no means of communication between the two cockpits.^[1]^[2]

Operational history

The MB-4 made its maiden flight in February 1920.^[1] While the aircraft had reasonable speed for the time,^[3] it was otherwise poor, with one fuselage tending to take-off before the other, while the engines caused severe vibration which overloaded the aircraft's structure.^[1]^[4] It was described as the "worst thing on wings" by Jerome Fried, the general plant superintendent of Thomas-Morse.^[1]

One aircraft was tested by the US Post Office, but was not used for mail services, and was scrapped in 1921.^[4] At least one MB.4^[1] (and possibly 3^[4]) was delivered to the United States Army Air Service where it was stored before being scrapped.^[1]

The MB-4 was a failure, having extremely poor flying characteristics and being described as the "worst thing on wings",^[1] and saw no service other than the trials by the manufacturer, US Army and the US Post Office.

Specifications

Data from General Dynamics Aircraft and their Predecessors^[1]

General characteristics

Crew: 2
Length: 25 ft 5 in (7.74 m)
Wingspan: 45 ft 6 in (13.87 m)
Height: 11 ft (3.4 m)
Wing area: 645 sq ft (59.9 m²)
Empty weight: 3,554 lb (1,612 kg)
Gross weight: 5,564 lb (2,524 kg)
Powerplant: 2 × Wright-Hisso H water-cooled V8 engines, 300 hp (220 kW) each

Performance

Maximum speed: 122 mph (196 km/h, 106 kn)
Stall speed: 53 mph (85 km/h, 46 kn) ^[2]
Range: 600 mi (970 km, 520 nmi)
Time to altitude: 9,000 ft (2,745 m) in 10 min

References

Notes

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Wegg 1990, p. 26.
^ ^a ^b ^c Flight 1 April 1920, p. 373.
^ ^a ^b ^c Eberspacher 2001.
^ ^a ^b ^c "Thomas, Thomas-Morse". aerofiles. 1 August 2008. Retrieved 22 January 2011.

Bibliography

Eberspacher, Warren. "Thomas-Morse MB-4". Excerpts from AAHS Journal, Vol. 46, No. 3 - Fall 2001.
"New York Aero Show". Flight, 1 April 1920, pp. 370–373.
Wegg, John. General Dynamics Aircraft and their Predecessors. London:Putnam, 1990. ISBN 0-85177-833-X.