P-1091 (Source: Messerschmitt "O-nine" Gallery)

In 1942 the RLM announced the need for a new high performance fighter. This fighter should be ready for operations late in 1944. In order to provide a quick solution to the problem, Messerschmitt offered a design based on the 109, the P-1091. This was in fact a stretched 109 in which the wings and the rear fuselage were enlarged. This aircraft was to have been powered by the DB 605 engine and armed with three MG 151 machine guns.

By the summer of 1943 it became clear that a higher operational altitude would be necessary. This led to the P-1091a which was similar to the P-1091 but powered by the DB 603U or DB 632. This last engine was an adaptation of the DB 603, designed for the use of two 4-bladed contra-rotating propellers.

As it became clear that the P-1091 could not be realized within a reasonable period of time, a new design was proposed. This was based on the Me-109H using a DB 628 engine. Contrary to the orders of the RLM, Messerschmitt continued the work on the P-1091, developing it into the P-1091b OR Me209H however.

To test the DB 628 engined design a mock-up of the engine installation was made in the Me-109 V-49, based on a G-5 airframe. The DB 628 was flight tested in the Me-109 V-50 and V-54. After the tests with the V-54, Messerschmitt abandonned all projects with the DB 628. The DB 628 program was cancelled in 1944.

P-1091a (Source: Messerschmitt "O-nine" Gallery)