I don't have my references to hand, but I believe this is the original--the 3m was the variant. The Ju52 was powered by a liquid-cooled Junkers L-5 engine in the 300-500 hp range. While the Ju52 was quite successful as a bush plane in Canada and Australia, the L-5 did not provide much power for an aircraft of that size. Three 700+ hp Pratt and Whitney Hornet radials (license-built by Bramo) greatly improved the airplane, particularly for airline and military use.
According to Turner & Nowarra, five "Ju-52/1m"s were built:
- Ju-52ba c/n 4001 D-1974 (first flight 13 Oct 1930), 800 hp Junkers L88
-- became Ju-52be with 755 hp BMW VIIau
- Ju-52d ? c/n 4002, 800 hp Junkers L88
-- possibly re-engined as Ju-52do, 750 hp Junkers Jumo 204 diesel
- Ju-52di ? c/n 4003 D-2133, 750 hp A-S Leopard radial
- Ju-52ce c/n 4004 D-2317/SE-ADM, 755 hp BMW VIIau
- Ju-52cai c/n 4005 D-2356, 750 hp BMW IXu
- Ju-52cao c/n 4006 CF-ARM, BMW VIIa then 825 hp RR Buzzard
Airframes differed slightly from the later Ju-52/3m. The Ju-52's vertical tail was smaller and horn-balanced and the Ju-52di was flown for a time with a shortened rear fuselage.