Junkers Ju 49
| Company type | Experimental aircraft |
|---|---|
| Industry | Aviation |
| Founded | 1931 |
| Headquarters | Germany |
| Products | High-altitude research aircraft |
The Junkers Ju 49 was a German-designed airplane created to investigate high-altitude aviation and the implementation of cabin pressurization. It was the second operational aircraft worldwide to feature a pressurized cabin, following the 1921 U.S. Engineering Division USD-9A. By 1935, it consistently achieved flight levels near 12,500 m (41,000 ft).
Development
Built expressly for high-altitude experimentation, the Ju 49 incorporated a custom-designed powerplant and was Germany’s inaugural aircraft with a pressurized cockpit. Its Junkers L88a engine merged two six-cylinder inline L8 engines into a V-12 configuration, equipped with a two-stage supercharger and intercooler to sustain output at elevated altitudes, delivering 522 kW (700 hp) at roughly 5,800 m (19,000 ft). This engine drove a sizable four-blade propeller. The pressurized compartment was designed to house two crew members and initially targeted operational ceilings near 6,000 m (20,000 ft).
Constructed using Junkers’ characteristic all-metal technique, the Ju 49 was a cantilever monoplane featuring stressed duralumin skin and corrugated flying surfaces. Its wing design included the Junkers “double wing” trailing edge system—consisting of adjustable flaps paired with outboard ailerons and inboard plain flaps. The fixed split-axle main landing gear was notably tall to provide clearance for the large propeller and was complemented by a tailskid.
A retractable rectangular radiator was installed between and ahead of the undercarriage legs. The pressurized cockpit contained five small portholes for the pilot—two positioned forward, two on each side, and one overhead—and two side windows for the second crew member. To address limited forward visibility, a periscope was added to offer downward views during landing approaches.
Operational history
During its maiden flight on October 19, the Ju 49 operated with an unsupercharged L88 engine because the supercharged variant had yet to receive approval. This engine setup featured a tall vertical exhaust stack in contrast to the single sloping pipe used on the L88a. By mid-1932, the supercharged engine became functional and was installed, initiating the primary research phase which proceeded smoothly without significant engine or cabin complications.
Originally aimed at altitudes near 6,000 m (20,000 ft), by 1933 the Ju 49 frequently reached 10,000 m (30,500 ft), and flights at around 12,500 m (41,000 ft) were commonplace by 1935. Although it did not establish any absolute altitude records, the knowledge gained directly influenced subsequent pressurized aircraft designs, particularly the Ju 86P bomber and reconnaissance models.
Only one Ju 49 was ever constructed, bearing registration D2688 and later D-UBAZ under updated German civil registration standards. Its operational life ended at the German research facility (Deutsche Versuchsanstalt für Luftfahrt) following a crash in October 1937.
Historical significance
During the late 1920s and throughout the 1930s, interest in achieving high-altitude flight intensified, with three primary methods being explored:
One approach involved supplying oxygen through face masks, which left pilots vulnerable to hypoxia and severe cold conditions. Aviators such as Cyril Uwins (reaching 13,408 m/43,990 ft in a Vickers Vespa in 1932) and Renato Donati (achieving 14,433 m/47,385 ft in a Caproni Ca 114 in 1933) operated open cockpits on brief up-and-down sorties due to limitations in pilot endurance.
Another technique employed was the use of pressure suits, introduced by Wiley Post beginning in 1934 with his Lockheed Vega 5C. These suits allowed for extended flights above 15,000 m (49,000 ft). Pilots like F.R. Swain (15,230 m/49,970 ft) and Mario Pezzi (17,083 m/56,047 ft) set altitude records on short climbs while wearing pressure suits. Post’s efforts demonstrated that prolonged high-altitude flights were achievable but also revealed the suits’ limitations in terms of comfort and mobility.
Ultimately, the development of the pressure cabin, which offered insulation or heating to preserve a normal environment for crew and passengers, became recognized as the most effective solution for operating at extreme altitudes.
Operators
Cited sources
- Cornelisse, Diana G. Splendid Vision, Unswerving Purpose; Developing Air Power for the United States Air Force During the First Century of Powered Flight. Wright-Patterson Air Force Base, Ohio: U.S. Air Force Publications, 2002. pp. 128–129.