Junkers Ju 288

Ju 288

Sole Ju 288A prototype (Ju 288 V5) with Junkers Jumo 222 engines and ducted spinners
Role	Advanced bomber Bomber B design competitor
National origin	Germany
Manufacturer	Junkers
First flight	29 November 1940
Number built	22
Developed from	Junkers Ju 88

Junkers 288B (Ju 288 V13, DB 606 engines) prototype

The Junkers Ju 288, originally known within the Junkers firm as the EF 074, was a German bomber project designed during World War II, which only ever flew in prototype form. The first of 22 development aircraft flew on 29 November 1940.

Design and development

Prior to the opening of World War II, the Luftwaffe bomber force included three major types, the Dornier Do 17 and Ju 88, both classed as schnellbomber, and the slower Heinkel He 111. Although as the most modern type the Ju 88 outperformed the other designs in service, it however possessed adverse characteristics, including its very small internal bomb bay that forced it to carry some of its load externally, degrading performance.

Junkers had been outlining a variety of improved models of the Ju 88 since 1937, powered by the planned Jumo 222 multibank engine, or Jumo 223 inline multibank diesel of greatly increased power of at least 1,500 kW/2,000 HP. No serious work was undertaken on these versions, but after Heinrich Hertel left Heinkel and joined Junkers in 1939, the EF 074 design was submitted to the RLM in May 1939 as the Junkers entry in the RLM's Bomber B design competition.

The EF 074 entry was essentially a scaled-up Ju 88, sharing its general layout and most of its fuselage and wings with extensions in various places. The nose was redesigned (as with the He 111P and -H's revised cockpits) with a more streamlined "stepless cockpit", having no separate windscreen panels for the pilot and co-pilot. This layout allowed cabin pressurization to be more easily implemented. This design approach had been growing in favour, subsequently appearing in various German types. All of the defensive armament was meant to be remotely controlled — in one proposal, comprising a remotely operated rear-facing dorsal turret at the rearmost end of the cockpit glazing, and two remotely operated "flank" turrets on the rearwards sides of the fuselage just forward of the empennage, otherwise each resembling the FDSL 131 units of the Me 210 – the exclusive use of remotely operated turrets for the Ju 288's defensive firepower allowed them to be positioned more efficiently, as well as eliminating "breaks" in the fuselage pressurization. The fuselage was expanded along its length to allow for a much longer bomb bay — somewhat as had been done with the Dornier Do 217 then in development itself — that would allow for an 3,630 kg (8,000 lb) payload to be carried internally, eliminating the need to carry ordnance on outside hardpoints.

Accordingly the RLM sent out the specifications for Bomber B in July 1939, the Ju 88 retroactively becoming the second aircraft to be designated Bomber A. (The original usage, dating from June 3, 1936, was the specification for what became the He 177). The Bomber B program aimed at replacing all of the medium bombers in the Luftwaffe inventory with a new design based on the EF.74 or something with equal performance. Bomber B was intended to have even better speed than the Ju 88, high-altitude cruising with a pressurised cockpit, heavier defensive armament, range allowing it to cover any point in the British Isles, and a 4,000 kg (8,820 lb) warload, double that of the earlier generation bombers. A number of companies returned proposals, but these were to some extent a formality, the EF.74 had already been selected as the winner, and of the rest of the designs submitted, only the Focke-Wulf Fw 191 and Dornier Do 317 progressed even as far as prototypes, and the Henschel Hs 130 coming under consideration as a late entrant.

Work began on building prototypes soon after, and the first example was completed by mid-1940. Power was supposed to be supplied by two 24-cylinder Jumo 222 six-bank, four cylinders per bank, over-1,500 kW output class powerplants, but problems with the Jumo 222's development — as with almost every new concept for over-1,500 kW output, reciprocating aircraft engines then underway in the Third Reich — meant the first prototypes flew with BMW 801 radial engines, instead. The first flight-quality 222s did not arrive until October 1941, and even at this point it was clear they were nowhere near ready for full-scale production. When it became apparent the 222 was not likely to become a viable powerplant, in May 1942, Junkers proposed replacing them with the much heavier Daimler Benz DB 606s instead, the same 1.5 tonne, twin-crankcase "welded-together engines" that Reichsmarschall Hermann Göring complained about some three months later, regarding the He 177's own endless powerplant troubles.

Undercarriage difficulties

Ju 288 V1 prototype (twin BMW 801) Actuation rod for main landing gear oleo-strut pivoting visible on portside of each maingear leg unit.

The Ju 288's intricate main landing gear system's design proved to be troublesome, possessing twin vertical members directly behind a single oleo strut,^[1] for each pair of twinned wheels mounted to the lower end of the uniquely-attached main oleo strut unit. This single-tube oleo strut was pivoted off the lower end of the twin-member, "Y-shaped" retraction strut assembly, and was rotated in the vertical plane about this single attachment in a rearwards direction during retraction of the maingear unit, separate from the twin-member unit to help "shorten" its stowed length within the engine nacelle. This distinctive type of design required the oleo strut's freely-moving top end to physically rotate downwards and aftwards during the rear-swinging retraction of the main "Y-shaped" member, operated by a lever and gear-sector system mounted on the portside of each main gear assembly, operated with a long lever that had its upper end anchored to the firewall's rear surface.^[2] The lever/sector gear system swiveled the oleo strut about its attachment point during the retract cycle, through an arc of roughly 180º from its position when the main gear was fully extended. The stowed position of the oleo strut ended up orienting it aftwards within the rear of the engine nacelle, and placing the wheels' axle location just ahead of and above the oleo strut's pivot point when fully retracted. Such a complex main gear design, with only the single pivoting retraction point for its oleo struts taking the primary stress of touchdown, was likely only one of the many potential sources of trouble causing the Ju 288's main gear units to repeatedly collapse on touchdown.^[3]

Operations

Although the 288 never even reached production status, let alone official operational service, the aircraft did see limited combat duty. In 1944, following the cancellation of the 288 programme, the surviving A and C series prototypes were hurriedly fitted with defensive armament and equipment and deployed as reconnaissance bombers on the Western Front. Very few missions were flown, owing to the scarcity of aviation fuel and spare parts, and the unresolved problems with the aircraft's powerplant and undercarriage. It is believed that the 288s were attached to the same unit operating the small number of Ju 388 reconnaissance planes that saw service.

Variants

Ju 288A - first seven prototypes with BMW engines
Ju 288B - seven prototypes with slightly enlarged airframes and better defensive armament
Ju 288C - final eight prototypes (of which only four were completed) with two Daimler-Benz DB 606 or 610 "power system" engines. This version was selected for serial production in 1944, but the programme was abandoned before that could take place.
Ju 288D - mock-up of a Ju-288C with improved tail armament
Ju 288G - design for an anti-ship version armed with a 355.6 mm (14 in) recoilless cannon

Specifications (Ju 288B)

Data from

General characteristics

Crew: 4
Length: 17.8 m (58 ft)
Wingspan: 22.7 m (74 ft 4 in)
Height: 4.50 m (14 ft 9 in)
Wing area: 64.6 m² (696 ft²)
Loaded weight: 20,950 kg (46,186 lb)
Max. takeoff weight: 21,000 kg (46,300 lb)
Powerplant: 2 × Daimler-Benz DB 606 24-cylinder "coupled" engine system, made from twinned DB 601 inverted V12 engines, 2,700 PS (1,985 kW, 2,663 hp) each

Performance

Maximum speed: 620 km/h (388 mph)
Range: 2,700 km (1,678 mi)
Service ceiling: 9,300 m (30,500 ft)
Rate of climb: 435 m/min (1,420 ft/min)

Armament

Guns:
- 4 × 13 mm (.51 in) MG 131 machine guns
- 1 × 15 mm (.59 in) MG 151 cannon or 20 mm MG 151/20 cannon
Bombs: 3,000 kg (6,610 lb) of bombs

References

Notes

↑ Archive photo of Ju 288 starboard main landing gear
↑ Junkers Ju 288 (Bomber B) (YouTube) (YouTube). History of the Third Reich. Event occurs at 1:28 to 1:33. Retrieved November 18, 2016.
↑ Sengfelder, Günther (1993). German Aircraft Landing Gear. Atglen, PA USA: Schiffer Publishing. pp. 175–177. ISBN 0-88740-470-7. The Ju 288's landing gear was most innovative in its design. A Y-shaped bearer was mounted in the engine nacelle with its upper arms hinged. At the bottom end of this bearer was the shock absorber leg, which was likewise hinged. Two double-brake wheels, with (metric) size 1015 x 380 tires, were mounted on the cross-axle. During the retraction cycle a folding strut was raised by a hydraulic jack. The bottom part of the folding strut drew the Y-bearer upwards. Functioning via a lever-and-gear arrangement, a pushrod positioned parallel to the Y-bearer acted upon another gear segment mounted to the oleo leg's hinge pin and rotated it about this as the Y-bearer was drawn upwards.

Bibliography

Hitchcock, Thomas H. Junkers 288 (Monogram Close-Up 2). Acton, MA: Monogram Aviation Publications, 1974. ISBN 0-914144-02-2.

External links

Wikimedia Commons has media related to Junkers Ju 288.

Junkers aircraft

Company	J 1 J 2 J 3 J 4 J 5 J 6 J 7 J 8 J 9 J 10 J 11 J 12 F 13 J 15 K 16 K 17 J 18 T 19 A 20 H 21 / J 21 / T 21 J 22 T 23 G 23 F 24 / G 24 A 25 T 26 T 27 J 28 T 29 K 30 G 31 A 32 W 33 W 34 A 35 S 36 K 37 G 38 K 39 K 47 A 48 A 50 K 51 K 53

Idflieg	CL.I D.I E.I J.I

RLM	Ju 46 Ju 49 Ju 52 Ju 60 Ju 85 Ju 86 Ju 87 Ju 88 Ju 89 Ju 90 Ju 160 Ju 187 Ju 188 Ju 248 Ju 252 Ju 268 Ju 287 Ju 288 Ju 290 Ju 322 Ju 352 Ju 388 Ju 390 Ju 488 Ju 635

"EF" (experimental)	EF 61 EF 126 EF 127 EF 128 EF 131 EF 132 EF 140 EF 150

Reich Air Ministry aircraft designations

1 to 100	B 9 Gö 9 Do 10 Do 11 Wn 11 Do 12 Do 13 Do 14 Do 15 Wn 15 Do 16 Wn 16 Do 17 Do 18 Do 19 Do 20 Do 22 Do 23 Do 24 Kl 25 Do 26 Kl 26 M 27 Do 29 Kl 31 Kl 32 W 33 L 33 W 34 Kl 35 Kl 36 HD 37 HD 38 G 38 DFS 39 BV 40 DFS 40 A 40 Fw 42 He 42 Fw 43 HD 43 Fw 44 He 45 He 46 Ju 46 Fw 47 Ju 47 K 47 A 48 He 49 Ju 49 He 50 A 50 He 51 K 51 Ju 52 K 53 NR 54 Fw 55 NR 55 Fw 56 Fw 57 Fw 58 He 58 He 59 He 60 Ju 60 Fw 61 He 61 Fw 62 He 62 He 63 Ar 64 He 64 Ar 65 He 65 Ar 66 He 66 Ar 67 Ar 68 Ar 69 He 70 He 71 He 72 He 74 Ar 76 Ar 77 Ar 79 Ar 80 Ar 81 Ju 85 Ju 86 Ju 87 Ju 88 Ju 89 Ju 90 Ar 95 Ar 96 Fi 97 Fi 98 Fi 99 He 100

101 to 200	Al 101 Al 102 Al 103 Fi 103 Fh 104 Kl 105 Kl 106 Kl 107 Bf 108 Bf 109 Bf 110 He 111 He 112 He 113 He 114 He 115 He 116 Hs 117 He 118 He 119 He 120 Hs 121 Hs 122 Hs 123 Hs 124 Hs 125 Hs 126 Hs 127 Hs 128 Hs 129 Hs 130 Bü 131 Hs 132 Bü 133 Bü 134 Ha 135 Ha 136 Hü 136 Ha 137 BV 138 Ha 139 Ha 140 BV 141 BV 142 BV 143 BV 144 Go 145 Go 146 Go 147 Ju 147 Go 149 Go 150 Kl 151 Ta 152 Kl 152 Ta 153 Ta 154 BV 155 Fi 156 Fi 157 Fi 158 Fw 159 Ju 160 Bf 161 He 162 Bf 162 Bf 163 Me 163 Me 164 Fi 166 FK 166 Fi 167 Fi 168 He 170 He 172 He 176 He 177 He 178 Bü 180 Bü 181 Bü 182 Ta 183 Fl 184 Fl 185 Fw 186 Ju 186 Fw 187 Ju 187 Ju 188 Fw 189 Fw 190 Fw 191 Ao 192 DFS 193 DFS 194 Ar 195 Ar 196 Ar 197 Ar 198 Ar 199 Fw 200

201 to 300	Si 201 Si 202 DFS 203 Si 204 Fw 206 Me 208 Me 209 Me 209 (1943) Me 210 Hü 211 Do 212 Do 214 Do 215 Do 216 Do 217 Hs 217 He 219 He 220 BV 222 Fa 223 Fa 224 Ao 225 Fa 225 BV 226 Ho 226 FGP 227 DFS 228 Ho 229 DFS 230 Ar 231 Ar 232 Ar 233 Ar 234 Do 235 BV 237 BV 238 Fw 238 Ar 239 Ar 240 Go 241 Go 242 Go 244 BV 246 Ju 248 BV 250 Fw 250 Ho 250 Ho 251 Ho 252 Ju 252 Fi 253 Ho 253 Ta 254 Ho 254 Fi 256 Sk 257 Fw 261 Me 261 Me 262 Me 263 Me 264 Fl 265 Me 265 Fa 266 Ho 267 Ju 268 Fa 269 He 270 We 271 Fw 272 He 274 He 275 He 277 He 278 He 280 Fl 282 Fa 283 Ta 283 Fa 284 Fl 285 Ju 286 Ju 287 Ju 288 Ju 290 Me 290 As 292 Hs 293 Hs 294 Hs 295 Ar 296 Hs 296 Hs 297 Hs 298 Fw 300

301-	Me 309 Me 310 Do 317 Do 318 He 319 Me 321 Ju 322 Me 323 Me 328 Me 329 Fa 330 DFS 331 DFS 332 Fi 333 Me 334 Do 335 Fa 336 Fl 339 E.340 WNF 342 He 343 Rk 344 So 344 Go 345 DFS 346 Rk 347 Ba 349 Ju 352 Me 362 Me 364 Ju 388 Ju 390 Fw 391 Ar 396 Ta 400 Me 409 Me 410 Do 417 He 419 ZMe 423 Ar 430 Ka 430 Ar 432 Do 435 Ar 440 Ju 452 Me 462 Ju 488 Fw 491 Me 509 Me 510 He 519 ZSO 523 Ar 532 Do 535 E.555 Me 609 Ar 632 Do 635

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