The Mercury Story

By Eugene Horsman

The Baumann Mercury B-100 was first flown on 1/3/40. The design was started while Jack Baumann was working at the original Taylor Aircraft Co, in Alliance OH, in the late '30s and was a personal project in his off-hours. When he left Taylor and returned to Knoxville TN, a number of other Taylor workers would drive all night to work with him on weekends. Several of them ultimately quit Taylor to go with Baumann a start a new company in Knoxville.

    A four-place, retractable-gear, negative-stagger wing biplane, the B-100 had full-span flaps on the upper wing and full-span ailerons on the lower. Wings were constructed of wood spars with aluminum ribs and steel tubing tips. All controls were cable operated. Tail surfaces were all-steel tubing with 3/8" steel channel ribs. The plane was covered with grade-A cotton and doped up through a silver UV coat.

    The original powerplant, a 100hp four-cylinder inverted, in-line, air-cooled Allied Monsoon, was to be the American licensed version of the French Regnier 4EO. It proved to be insufficient power and was unable to be cooled properly, so was replaced with a Ken-Royce 120-G for a first flight of the B-120 on 4/28/40. The radial was not cowled, and no pictures of that configuration have been found.

    In the meantime, the struggling little company was looking for a home. The city fathers of Menominee MI invited them to bring the ship up there, and eventually made a deal to furnish a place to build airplanes and purchased stock to start the new company. The B-120 was flown there on 4/2/40 to give demonstration rides to potential stockholders. It had flown a total of 50 hours at that time and never flew again, but cut up instead to teach new workers how to weld tubing and build wing and tail components.

    With war looming, they decided that the four-place would not sell and that something was needed to deal with the government on. It was decided to make a two-place trainer out of the design, to be aimed at the Civilian Pilot Training Program as a primary aerobatic trainer.

Thus the BT-120 was born. (All of Jack Baumann's designs were designated "B" with the horsepower of the engine. "T" was for Trainer.) The gear was fixed and the upper longerons were moved inboard to narrow the fuselage from the four-place. Flaps were deleted from the upper wing, but full-span ailerons kept on the lower wing. Everything else was the same except for the cockpit instrumention and engine controls. Since it was a trainer, both cockpits had instruments, fuel shut-off, mag switches, and trim system.

    Prototype s/n 1 had spats on the gear and a short engine mount. It flew well, so Baumann decided to go for an Approved Type Certificate. However, s/n 1 was cut up for employee training, and tooling was built for production.

    The first plane built from the tooling, s/n 2, did all the test flying for the CAA certification, as well as the static load tests. During testing it was found that the airplane did not meet the CAA spin test requirements. Six weeks of time was lost fixing the problem, and by then stockholders were getting jittery. ATC was issued in July 1941, parts were made for 10 airplanes, but only s/ns 2 and 3 were completed before halting production for lack of funds. Baumann Company formally closed in July 1942.

    S/n 2 actually was used teach CPTP students in Kansas before being moved to Michigan and then Ohio. It is currently being restored by this writer in Golden CO. S/n 3 ended up as a powered iceboat on Green Bay and then was scrapped.  (1/6/02)