Junkers Ju 288
| Industry | Aerospace, Defense |
|---|---|
| Founded | 1895 |
| Headquarters | Germany |
The Junkers Ju 288, originally designated as the EF 074 within Junkers, was a German bomber initiative developed during World War II that never progressed beyond the prototype phase. Its maiden flight took place on 29 November 1940, with a total of 22 units constructed for testing purposes.
This aircraft emerged as the winner of the Bomber B contest, although Junkers' design was favored from the outset. The Bomber B program aimed to produce a Schnellbomber intended to succeed the Junkers Ju 88. The Ju 288 incorporated a larger airframe, pressurized cockpit for operations at high altitudes, extended operational range, markedly increased bomb capacity, improved speed, and superior defensive weaponry. It was designed to replace all bombers then active in the Luftwaffe inventory.
To realize these ambitious performance goals, significantly more powerful engines were necessary; the project relied heavily on the Junkers Jumo 222 engine. Despite nearly 300 prototype engines being built and extensive development efforts, the Jumo 222 never reached operational deployment. The absence of a reliable powerplant ultimately led to the failure of the Ju 288 project, forcing the Luftwaffe to continue using outdated bomber models during the war’s later stages.
Design and development
Prior to World War II, the Luftwaffe operated three primary bomber models: the swift Dornier Do 17 and Junkers Ju 88, alongside the larger but slower Heinkel He 111. Although the Ju 88 outperformed its counterparts in speed and versatility, its limited internal bomb bay capacity necessitated carrying weapons externally, which negatively impacted aerodynamic efficiency.
Starting in 1937, Junkers pursued upgraded Ju 88 variants powered by advanced engines such as the projected Junkers Jumo 222 multibank or Junkers Jumo 223 diesel engines, aiming for output near —a considerable engineering challenge for German manufacturers at that time. The EF 074 was essentially an enlarged Ju 88 featuring an extended fuselage and wingspan. Its cockpit adopted a streamlined "stepless" design without separate windscreen panels for pilot and co-pilot, facilitating cabin pressurization—a feature increasingly common in German bombers like the He 111P and -H models.
The defensive weaponry consisted solely of remotely operated turrets: a rear-facing dorsal turret positioned at the aft edge of the cockpit glazing and two "flank" turrets located near the rear fuselage sides, similar to those installed on the Messerschmitt Me 210. This configuration enabled effective turret placement without compromising fuselage pressurization.
The lengthened fuselage housed an expanded internal bomb bay—comparable to developments seen on the Dornier Do 217—capable of accommodating up to 3,630 kg (8,000 lb) of bombs internally, removing dependence on external hardpoints.
Bomber B Competition
Following Heinrich Hertel’s transfer from Heinkel to Junkers in 1939, the EF 074 design was submitted to the RLM in May that year. In July, the RLM issued specifications for the Bomber B competition aimed at replacing all medium bombers in Luftwaffe service with a new aircraft based on EF.74 or similar performance criteria. Bomber B demanded greater speed than the Ju 88, high-altitude cruising capability with a pressurized cockpit, enhanced defensive armament, operational range sufficient to reach the British Isles, and a bomb load of approximately 4,000 kg—twice that carried by earlier designs. While multiple manufacturers presented proposals, EF.74 was effectively preselected; only Focke-Wulf’s Fw 191 and Dornier’s Do 317 advanced to prototype stages, with Henschel’s Hs 130 entering consideration later.
Prototype production commenced rapidly, with the first aircraft completed by mid-1940. Initially intended to be powered by two 24-cylinder Jumo 222 engines delivering over 1,500 kW each, development delays forced early prototypes to fly using BMW 801 radial engines instead. Flight-capable Jumo 222 units became available by October 1941 but were still not ready for mass production. By May 1942, Junkers proposed fitting Daimler-Benz DB 606 engines—the heavy "twin-block" powerplants notorious for reliability issues criticized by Reichsmarschall Hermann Göring during Heinkel He 177 operations—on the Ju 288C variant as an alternative power source.
Challenges with the Undercarriage
The Ju 288's main landing gear was notably complex, incorporating twin vertical struts that formed a distinctive "Y-shaped" retraction mechanism located behind a single oleo strut for each paired wheel assembly. This oleo strut, consisting of a single tube, pivoted at the base of the Y-shaped frame and rotated rearwards during gear retraction to reduce the stowed length inside the engine nacelle.
Each main gear unit utilized a lever and gear-sector mechanism to facilitate approximately 180 degrees of rotation throughout retraction. This action positioned the oleo strut toward the rear within the nacelle while situating the wheel axles just above its pivot point when fully retracted.
The complexity of this system—with touchdown forces concentrated on a single pivot—was likely a primary cause behind frequent collapses of the main landing gear during landings. This innovative configuration combined a Y-shaped load-bearing structure with hinged upper arms, a shock-absorbing leg, dual-brake wheels, and a hydraulically operated folding strut that rotated the oleo leg as the gear retracted.
Operational Background
Despite never advancing to mass production or official frontline deployment, surviving prototypes from the A and C series were equipped with defensive weaponry in 1944 and utilized in reconnaissance bombing roles on the Western Front. Their operational scope was limited by shortages of fuel and spare parts, alongside persistent engine and undercarriage reliability problems. It is believed that these Ju 288s operated in conjunction with Ju 388 reconnaissance aircraft during this period.
Model Variants
- Ju 288A – initial seven prototypes powered by BMW engines
- Ju 288B – seven prototypes featuring enlarged airframes and upgraded defensive armament
- Ju 288C – last eight prototypes (four completed) equipped with Daimler-Benz DB 606 or DB 610 engines; chosen for serial production in 1944 but canceled prior to manufacturing
- Ju 288D – mock-up based on Ju 288C with improved tail defensive armament
- Ju 288G – proposed anti-ship version armed with a 355.6 mm recoilless cannon
Sources
- Hitchcock, Thomas H. Junkers 288 (Monogram Close-Up 2). Acton, MA: Monogram Aviation Publications, 1974. .