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Project Junkers EF 52
On March 30, 1933, in Sweden, the Flygstyrelsen (General Administration of the Swedish Air Force) requested various domestic and foreign companies to submit proposals for a single- or twin-engine torpedo bomber, available with either land-based landing gear or floats. Among the aircraft manufacturers contacted was AB Flygindustri (AFI).

The request was immediately forwarded by Limhamn to Dessau, where it met with considerable interest. Between May 11 and 13, 1933, Messrs. Thornberg and Svensen, officers of the Swedish Air Force, were in Dessau and, among other things, had a meeting concerning a "twin-engine bomber and torpedo aircraft" with the head of the JFA design office, Ernst Zindel. On June 20, 1933, AFI then submitted its offer No. 25137 to the Swedish Air Force. It concerned the twin-engine "Junkers high-speed aircraft type EF 52," suitable as a torpedo bomber, land bomber, and long-range reconnaissance aircraft.

The EF 52 project featured the following details:

- Airframe predominantly of smooth sheet metal construction,twin tail assembly,

- fixed landing gear (possibly retractable in a later development stage), or alternatively, a floatplane with two floats of 6400 liters each,
- propulsion by two Bristol "Pegasus" M2 radial engines, each producing 616 hp,

- a so-called "canopy" in the nose forward of the cockpit with a defensive position as well as bomb aiming and torpedo release equipment,

- a defensive position behind the cockpit on the fuselage spine similar to that of the Junkers K 47,

- storage of torpedoes and 250 kg bombs as external load under the fuselage, smaller bomb calibers were to be carried in the fuselage in horizontal or vertical suspension.

The evaluation of the received bids apparently took several months, because in November 1933 no decision had yet been made as to which company would be awarded the contract.
According to information from November 11, 1933, a total of four types were in discussion
The shortlisted aircraft, all equipped with the Bristol "Pegasus" M2 radial engines required by the client, were: Fokker T IV, Boulton-Paul "Sidestrand", Heinkel P. 997, and Junkers EF 52.
On November 17, 1933, the Tekniska Byrån (Technical Bureau), belonging to the main administration of the Swedish Air Force, finally announced that of the offered aircraft models, only the Junkers EF 52 was suitable; all other aircraft would not meet the required performance standards.
At the beginning of December 1933, the Swedish Air Force officer Adilz traveled to Dessau to discuss further details.
In particular, the question also had to be clarified whether scarce materials such as aluminum could be stockpiled in sufficient quantities in Sweden so as not to be dependent on the goodwill of foreign—that is, German—manufacturers in an emergency. To understand this, one must know that for many years Sweden had not purchased Junkers military aircraft solely because these were made of duralumin (an aluminum alloy), and aluminum was considered a critical commodity for which imports from abroad were necessary.

Source JET & PROP 5/04