The Bartel M.2 (BM 2) was a biplane trainer that only reached the prototype stage, but that was followed by a series of related Bartel trainers that did enter production.
The M.2 was designed by Ryszard Bartel, who made his name researching new aerofoil designs. His first aircraft design was the Bartel M.1, a high wing monoplane designed for a Polish design contest of the mid 1920s, in which it came fourth, although it was never built.
Soon after this, Bartel joined the Samolot company, becoming their chief designer. In May 1926 he began work on a biplane trainer. Although the Polish government wasn’t interested, Samolot decided to build two prototypes – one flying and one structural test airframe – at their own cost.
The M.2 was a two-seat biplane with unequal span unstaggered single bay wings. The four wing sections were interchangeable, with the upper wings meeting in the middle and the lower wings attached to the fuselage bottom longerons. As a result the lower wings had a longer span (by the width of the fuselage). Most of the aircraft was of wooden construction, apart from the steel tube framework for the tail, a fabric covering for most of the wings and tail (plywood on the leading edges and undersurfaces) and sheet duraluminum for the forward part of the cockpit. Both cockpits carried full controls. The pupil sat in the front cockpit, which also had the instruments, but they could also be seen from the rear. Power was provided by a 120hp Salmson AC.9 nine-cylinder air-cooled radial engine.
The flying prototype made its maiden flight on 7 December 1926 with the factory test pilot at the controls. By May 1927 it had made 150 flights for a total of over 80 hours of flying time, including some at the hands of Service pilots. Reports on the aircraft were generally positive, and although it didn’t enter production, it was followed by a series of improved models that did.
The M.2 became the basis of two different production aircraft, both produced in response to a Polish government requirement, one for a primary trainer using war surplus engines and one for an intermediate trainer. Samolot produced the Bartel M.4 to satisfy the primary trainer requirement and the Bartel M.3 for the intermediate trainer. The M.4 entered production, but the M.3 was replaced by the more advanced Bartel M.5.
Engine: Salmson AC.9 nine-cylinder air-cooled radial engine
Span: 38ft 7.5in
Length: 25ft 7in
Height: 10ft 2.25in
Empty Weight: 1,532lb
Gross Weight: 2,138lb
Maximum Speed: 79.5mph at sea level
Climb rate: 7min to 3,280ft