J.Forsgren The Thomas-Morse MB-3 (A Centennial Perspective on Great War Airplanes 60)

The Thomas-Morse MB-4

  Designed in response to a US Post Office Department specification, the MB-4 two-seat biplane used major components of the MB-3 pursuit. Issued in June 1919, the specification called for ten aircraft capable of carrying 1,500 lb of air mail when flying on one engine. The aircraft was to be fitted with two or three Liberty or Hispano-Suiza engines. For its time, the MB-4 basic configuration was quite novel. The two Wright H engines, mounted in a tractor-pusher configuration in a centrally placed nacelle, were flanked on each side by modified MB-3 fuselages. The primary pilot sat in the port fuselage, with the starboard fuselage housing the second pilot/mechanic. The payload was located in the center nacelle. The three-bay wings were of unequal-span. The MB-4 was the first tractor-pusher aircraft constructed in the USA. Completed in early 1920, the MB-4 was test flown at Ithaca on a few occasions in February. The MB-4 exhibited quite a few substandard features, including no possibility for the two pilots to communicate when airborne, the engines causing severe airframe vibration, an inadequate fuel system, etc. Take-offs were usually asymmetric, with one of the fuselages lifting off the ground before the other. The Thomas-Morse factory superintendent Jerome Fried held a rather pessimistic opinion of the MB-4, calling it the 'worst thing on wings.' Post Office Department officials were present for a March 1 test flight. In the event, the Post Office Department decided against ordering the MB-4. The prototype was scrapped in 1921. However, the USAAS briefly considered a bomber development of the basic MB-4. Three MB-4s, serial numbers A.S.64306 and 64373/64374 were ordered for evaluation. The first of these arrived at McCook Field on September 23, 1921. Fitted with two 300 h.p. Wright H engines (serial numbers 13506 and 13508), the MB-4 was assigned the McCook Field serial number P172. Unfortunately, the outcome of these tests remain unclear.

MB-4 Technical Data and Performance Characteristics
   Wingspan: 45 ft 6 In (13,87 m) (Upper) 41 ft (12,5 m) (Lower)
   Length: 25 ft 4 3/4 in (7,71 m)
   Height: 7 ft 10 in (2,39 m)
   Empty weight: 3,554 lb (1,613 kg)
   Gross weight: 5,564 lb (2,526 kg)
   Maximum Speed: 140 mph (225 km/h)
   Climb to 10,000 ft (3,048 m): ten minutes
   Range: 600 miles (965,4 km)



The Thomas-Morse MB-6

  A dedicated air racing variant of the MB-3, designated MB-6, was to represent the USAAS in the 1921 Pulitzer Air Race, due to be held in Detroit, Michigan, in November that year. On 24 May 1921, a $ 48,000 contract was placed with Thomas-Morse for three MB-6s, serials 68537, 68538 and 68539. According to the contract, the MB-6 was to have a top speed of 175 mph, and a landing speed of 75 mph. The MB-6 was basically an MB-3 with reduced wingspan, having single-bay wings. One other difference was that the single radiator was fitted in front of the engine. The USAAS was to supply Wright-built Hispano-Suiza H-2 engines, propellers and instruments. However, in July 1921, the War Department decided that participation in the forthcoming air race would be too expensive, thus withdrawing military support for the MB-6 as well as the Navy's MB-7. Thinking that the lack of military aircraft would reduce public interest in the event, Detroit officials withdrew their support. The following month, a new venue was found in Omaha, Nebraska. Nevertheless, work on the three MB-6s continued.
  According to the original delivery schedule, the MB-6s were due to be delivered by August 23. However, the delivery date had to be amended twice, with the three MB-6s not being handed over until September 20. Orders soon arrived to use the second MB-6, A.S.68538, for static weight tests. Flight testing at McCook Field was to commence when the static tests had been completed. MB-6 68537 was flown for the first time on October 21, with Lieutenant. John A. Macready at the controls. During the fifteen-minute flight, an average speed of 110 mph was attained, with one high speed run of 182 mph. Macready stated that the MB-6 was "tricky, but not dangerous." A second flight, this time with Captain Corliss C. Moseley at the controls, took place on October 23. Two days later, the MB-6 was destroyed in a landing accident. The cause was found to be a faulty fuel pump. Moseley was lucky to escape serious injury. The third, unassembled MB-6, A.S.68539, had been shipped to Omaha by Thomas-Morse at the company's own expense.
  Flown by Lieutenant Macready, the MB-6 (assigned racing number 2) ended third with an average speed of 160,83 mph. Having crossed the finishing line, the Wright H-2 engine stopped. During the race, the engine had been run at full throttle, overheating slightly. Macready put the MB-3 into a dive to avoid stalling, attempting a downwind landing. The engine then decided to start working once again, with Macready making a normal landing.
  The MB-6 was then disassembled, and returned to McCook Field. Although reassembled and redesignated as the R-2, it appears that the aircraft was not flown again. Consigned to storage, the R-2 was removed on October 31, 1924, to suffer the ignomy of being used for crash tests. Placed on a track, the R-2 was then crashed into a concrete wall, completely destroying the aircraft.

MB-6 Technical Data and Performance Characteristics
   Wingspan: 19 ft (5,79 m)
   Length: 18 ft 6 in (5,64 m)
   Height: 7 ft 10 in (2,39 m)
   Weight: 2,023 lb (918 kg)
   Wing Area: 157.11 sq ft (47,9 m2)



The Thomas-Morse MB-7

  The MB-7 was custom-built for the US Navy for participation in the 1921 Pulitzer Air Race. It was part of a May 16, 1921 contract, covering ten MB-3s and two MB-7s to be supplied to the US Navy. USMC The aircraft were due to be delivered in November 1921. Although the fuselage and tail surfaces remained similar to that of the MB-3 and MB-6, the MB-7 was a high-wing monoplane. The wing was of novel design, known as the Alula wing. Developed in Great Britain by the Commercial Aeroplane Wing Syndicate, Ltd, the leading edge of the Alula wing tapered off sharply towards the wing tips. This would, it was thought, reduce the span-wise flow and the resulting tip losses. For the MB-7, the Alula wing was further modified, having a thicker airfoil as well as reduced wing taper to increase aileron effectiveness. When viewed from straight ahead, the MB-7s wing had the appearance of a humped gull wing. Thomas-Morse test pilot Paul D Wilson performed initial taxiing trials.
  On October 24, 1921, Harold Evans Hartney performed the MB-7s maiden flight at Ithaca. By this time, Hartney had been promoted to Colonel. The following week, the MB-7, A.S.64373, was shipped to Omaha. However, due to the War Department cancelling military participation on the grounds of high cost, the MB-7 was sponsored by Thomas-Morse.
  Following arrival at Omaha, the MB-7 was allotted racing number 2. However, fuel pump problems proved so severe that Hartney did not manage to take-off until after all the other participants had landed. Unfortunately, the fuel pump failed yet again during the race, with Hartney crashing at the Campbell family farmstead. Hartney was thrown clear when his MB-7 impacted the ground, suffering a broken thigh bone and a fractured hip. Assisted by members of the Campbell family, Hartney told them to "Telephone my wife and tell her I've sprained my ancle".
  The crashed MB-7 was soon at the mercy of 'souvenir hunters' who proceeded to strip the wreck of anything that could be carried away. To add insult to injury, one bystander, Fred Offertag, carelessly lit a cigarette, tossing the match near the remains of the MB-7. The wreck caught fire, being completely destroyed. When told about the demise of his aircraft, Hartney burst into tears.
  The second MB-7, serial number A.S.64374, was completed in February 1922. Powered by a 400 h.p. Wright H-3 engine, it was otherwise identical to the first MB-7. In March 1922, the second MB-7 was shipped to Mitchel Field. Here it was flown by Capt. Francis P. Mulcahy, who later reminisced that "The MB-7 was continually a source of trouble due to the insufficient cooling of the engine at high power settings." Nevertheless, Mulcahy remembered that the MB-7 performed well, although the poor forward view made landings problematical.
  Mulcahy flew the MB-7 in the 1922 Pulitzer Air Race, where it was allotted racing number 7. However, due to the engine overheating - despite an auxiliary radiator having been fitted - Mulcahy was forced to drop out after two laps, having averaged a speed of 145 mph on the first lap.
  The MB-7 was then transferred to the USMC, with the serial number being changed to A-6071. In his book United States Navy and Marine Corps Fighters 1918-1962, Paul R Matt claims that the MB-7 was classified as a pursuit, despite not being armed, and used as a continuation trainer.
  Another source states that the MB-7 was shipped to the Naval Aircraft Factory at Philadelphia, eventually being stricken on May 5, 1925.

MB-7 Technical Data and Performance Characteristics
   Wingspan: 24 ft (7,315 m)
   Length: 18 ft 6 in (5,64 m)
   Height: 7 ft 3 in (2,21 m)
   Wing Area: 112 sq ft (34,14 m2)
   Gross Weight: 2,000 lb (908 kg)
   Maximum Speed: 180 mph (290 km/h)