| 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.
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]
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.
Data from General Dynamics Aircraft and their Predecessors [1]
General characteristics
Performance
Aircraft of comparable role, configuration, and era
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