Ha 137

Dive bomber
First flight: 1935
Blohm und Voss

The Ha.137 cantilever monoplane had a Vogt-designed wing with a tubular spar, the central part of which was welded from a steel sheet and was a fuel tank with a capacity of 270 liters. The cantilever parts of the spar are riveted from duralumin. Flaps on the center section and on the inside of the consoles; released hydraulically. The landing gear was mounted on a wing break with double air-damped struts and covered with removable fairings. The fuselage was of rectangular semi-monocoque design, the pilot sat in an open cockpit behind the wing. It was possible to install two synchronous MG-17 machine guns and a couple more in the chassis fairings, where there was room for installing a 20mm MGFF gun if necessary. Engine VMW-132a-3 (licensed "Hornet") take-off power of 720hp and 650hp at nominal.

October 9, 1934 the aircraft was approved by the mock-up commission. The first experimental Ha.137-V1 (D-IXAH) was completed and flew in April 1935. in Hamburg. It was soon followed by the second Ha.137 V2 (D-IBGI). In the meantime, the RLM clarified the concept of the "Sturzbomber", demanding that it be made two-seater. Vogt from the very beginning believed that the two-seat version was more preferable in terms of defense, but this required the creation of a larger aircraft than determined by the original assignment, the new specifications were actually adapted to one of the Ha.137 competitors - the Junkers Ju.87, which RLM favored from the very beginning, and which thus gained an advantage over other projects. As for the single-seat Ha.137, it very much resembled the Ju.87, although this resemblance was purely accidental, despite the fact that in 1940 the creator of the Ju.87, Hermann Pullmann, joined Blom und Voss.

Despite the H.137 mismatch with the new task, the RLM decided to continue work on the aircraft as a stand-in for the main program or as a close support aircraft. There were orders for three more experimental aircraft under the Jumo-210 water-cooled engine. The first two experimental aircraft with an air-cooled engine were considered as a prototype for the Ha.137a. The third experimental Ha.137-VZ (D-IZIQ) was completed with a Rolls-Royce Kestrel-V engine, a 12-cylinder liquid-cooled engine, and was considered as a Ha.137b prototype. The turbocharged engine developed 525 hp on takeoff. and 640 hp at an altitude of 4270 m. Wooden propeller, fixed pitch, instead of a metal variable pitch on V1 and V2. Testing of the first two aircraft began at Travemünde in the summer of 1935. The V1 was damaged during weapons testing in October when ammunition in the right wing exploded. Ha.137 proved to be a very durable machine with good flight characteristics and pleasant to drive. True, the review on takeoff and landing was not particularly liked by the pilots.

Ha.137-VZ took part in dive bombing tests conducted in Rechlin in June 1936. Ernst Udet, as head of the Design Section of the Technical Department, did not really favor Vogt's aircraft and preferred dive bombers. Vogt was informed that there would be no order for the Ha.137.

In the meantime, the designers of the "Hamburger Flygzeugbau" decided to create a naval version of the Ha.137a, capable of operating from an aircraft carrier. The deck version of the aircraft received the designation "project-11", and "project 11a" was a float version. Insufficient flight range and a single-seat layout predetermined the lack of interest in this option.

Work continued on the next three experimental aircraft powered by the 590 hp Jumo-210a engine. on takeoff and 610 hp. at an altitude of 2600 m. These were V4 (D-IFOE), V5 (D-IUXU) and V6 (D-IDTE). Moreover, Ha.137-V6 flew before V5 and was lost in an accident in early July 1937, V5 was completed in October 1937. The two remaining Jumo-powered aircraft were used for various tests. One of them launched 65 mm Rheinmetall-Borsig rockets for the first time.

Aviation of World War II

Ha 137

Bibliography