Junkers Ju 52

Before there was a trimotor, the Junkers Ju 52 was a single-engined aircraft, and it was simply called the Ju 52 until the arrival of the Ju 52/3m made it necessary to call it the Ju 52/1m. It was conceived by the Junkers design office at Dessau under Ernst Zindel as a low-wing freighter that drew on experience with the W 33 and W 34. The brief was precise: carry two tonnes of payload into and out of improvised airfields with short runways, what would now be called STOL performance. To that end it used the patented Junkers double wing, with its auxiliary surface running along the trailing edge, and a particularly sturdy undercarriage that could be swapped for skis or floats as conditions required. It was flown by two pilots. The 20 m³ hold was loaded through two large doors on either side of the fuselage, which earned it the German nickname “flying furniture van” (Fliegender Möbelwagen). At least the example that went to Canada also had a roof hatch so that the bulkiest items could be lowered in by crane.

Sources disagree on the date of the first flight. The German Wikipedia article devoted to the 1m places it on 11 September 1930, with works number 4001 flown by Junkers chief pilot Wilhelm Zimmermann under the designation Ju 52ba; the English article gives 13 October 1930 in one passage and 3 September 1930 in another, and the Spanish one settles on 13 October. That first aircraft flew with a 588 kW Junkers L88 V12; it soon received a 507 kW twelve-cylinder BMW VIIau, was renamed Ju 52be and carried the registration D-1974. Luftfrako Air Express GmbH put it into service in June 1933 but, unhappy with its performance, soon handed it back.

Following those trials the wings were modified, the rudder was improved and three more aircraft were built to that layout, the Ju 52ce, also BMW VIIau-powered and numbered 4002, 4003 and 4004. Each went its own way. Number 4002 was used to measure performance with the Junkers Jumo 4 diesel and was designated Ju 52do. Number 4003 received the improved BMW VIIa and floats and was handed to a naval flying squadron. Number 4004 was sold to the German commercial flying school (Deutsche Verkehrsfliegerschule) and in 1932 went to Sweden as D-2317, where AB Flygindustri converted it into a torpedo aircraft; back in Germany it was tested in that role as the Junkers K 45c and proved too sluggish for it. Number 4005 was fitted with a 588 kW BMW IXau, delivered in February 1933 to the German aircraft industry association (Reichsverband der deutschen Luftfahrtindustrie) and test-flown at Berlin-Staaken until a fire destroyed it completely in May of the same year. The English Wikipedia allocates some engines and works numbers among the prototypes differently, a discrepancy worth keeping in mind.

The example with the longest career was 4006. It reverted to the original tail shape, received a 551 kW Armstrong Siddeley Leopard radial and was delivered on floats to Canada. There, Western Canada Airways, founded in 1926 by James A. Richardson, served almost every corner of the country by 1929 with wood-and-fabric aircraft that could not carry the heavy drilling equipment demanded by the mines of north-western Ontario. Richardson, who had heard of the huge all-metal Junkers, ordered one of the first six in 1930; by the time it arrived the following year, in late 1931 according to the English Wikipedia, the company had been reorganised as Canadian Airways Limited. Registered CF-ARM, it was the largest aircraft in Canada and the largest single-engined aircraft in North America, and it became known there as the “Flying Boxcar”. From the Brandon Avenue base on the Red River in Winnipeg it carried mining equipment, cattle and loads too big and heavy for the other aircraft then in use, landing on huge specially designed floats. Its load is given as 2,000 kg with a maximum weight of 6,600 kg by Wikipedia, while the Royal Aviation Museum speaks of a capacity of nearly 8,000 pounds.

The lack of power was felt in Canada too. In 1936 the Leopard gave way to a 606 kW Rolls-Royce Buzzard, a configuration the German Wikipedia calls the Ju 52cao. Pilot Stu McRorie recalled that the engine torque was such that on skis the aircraft simply could not be held straight on the take-off run. In 1942, by then under Canadian Pacific Air Lines, it was ordered to Dease Lake in the British Columbia Rockies: at that altitude and fully loaded it could not get airborne, and it had to be unloaded and flown back to Winnipeg. As no suitable, more powerful engine could be found, CF-ARM was retired in 1947 and dismantled for scrap; its floats ended up supporting a yacht club dock and part of its all-metal body became a child's playhouse.

The last aircraft, 4007, first served as a test bed: from April 1931 it carried two dummy engines on the wings to study the altered airflow, the step that led to the trimotor, and four further airframes already under construction were completed as Ju 52/3m. In 1935/1936 it went, as D-UHYF, to the target-towing squadron at Kiel-Holtenau. Junkers had overestimated demand for such a large freighter, and production stopped at seven aircraft according to the German source, six according to the English and French ones. Those that remained in Germany were eventually used up by the Luftwaffe as target aircraft.

For the Ju 52/1mce the German source gives a length of 18.5 m, a span of 29.5 m, a height of 4.65 m and a wing area of 116 m²; 4000 kg empty, a total disposable load of 3000 kg, of which 1820 kg was payload, and 7000 kg at take-off. The BMW VIIaU delivered 690 PS at 1650 rpm for take-off and 600 PS at 1575 rpm continuous. It reached 195 km/h near the ground, cruised at 160 km/h and landed at 80 km/h; it climbed at 2.30 m/s, had a service ceiling of 3400 m, a range of 1000 km and an endurance of up to 6.5 hours, and needed a 315 m take-off run and a 200 m landing roll.

No original Ju 52/1m survives. The Royal Aviation Museum of Western Canada in Winnipeg displays a static replica of CF-ARM built from a CASA 352 made in Madrid in 1948 (works number 039) that had been used by Escuadrón 721 for parachute training. The museum bought it in 1982 from a museum in Orlando, Florida, and had it flown to Gimli with the help of 402 Squadron of the Canadian Air Reserve. On 16 August 1984 it was towed to Bristol Aerospace in Winnipeg, and by April 1985 the trimotor had become a single-engined aircraft, painted with the flying goose emblem of Canadian Airways. In that same year of 1982 the museum's divers recovered one complete float and part of the other from the real CF-ARM, and they now sit beside the replica.