Saab J 21R

The Saab J 21R was a pioneering Swedish fighter‑bomber that entered service in the early 1940s, representing the only successful conversion of a piston‑engine aircraft to jet propulsion in the world. Developed by Saab Group as a retrofit of the earlier J 21A twin‑boom, piston‑powered fighter, the J 21R replaced the inline engine with a de‑rated German Jumo 004B turbo‑jet mounted in the rear fuselage. The aircraft retained its distinctive twin‑boom, wooden‑skinned wing and tail configuration, giving it a high lift-to-drag ratio and excellent low‑speed handling. First flown on 26 February 1945, the J 21R achieved a top speed of about 750 km/h (470 mph) and a service ceiling of 11 000 m, outperforming many contemporary prop‑driven fighters. Although only 38 units were produced before being superseded by the indigenous Saab J 29 Tunnan, the J 21R proved the viability of jet conversion and gave Swedish pilots valuable experience with jet flight before post‑war designs were available. Its mixed‑construction airframe and rear‑jet arrangement influenced later Scandinavian aircraft design, and the J 21R remains a symbol of Sweden’s rapid adaptation to jet technology during a pivotal era in aviation history.

Saab Group

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Design & Classification