Arado Ar 81

Ar 81
Role	Dive bomber
National origin	Germany
Manufacturer	Arado Flugzeugwerke
Designer	Walter Blume
First flight	1935
Number built	3

The Arado Ar 81 was a German prototype dive bomber. Because the Reich Air Ministry decided to purchase the competing Junkers Ju 87, only three prototypes of the Ar 81 were completed.

Development

In 1934, the Reich Air Ministry or RLM (Reichsluftfahrtministerium) initiated two parallel programmes to build new dive bombers for the German air force, to replace the Heinkel He 50. The first, the so-called Sofort or immediate program, aimed to develop an interim dive bomber, and resulted in the production of the Henschel Hs 123. The second, Sturzbomber program, aimed to produce a more definitive aircraft. In January 1935 the formal requirements for this were sent out to German aircraft manufacturers.^[1] These had been written around the Junkers Ju 87, of which the first prototype was already under construction. Indeed, the Luftwaffe had already given Junkers an order for 118 aircraft.^[2] Nevertheless, two manufacturers received an order to deliver three prototypes of their competing projects: The Heinkel He 118 and the Arado Ar 81. The Blohm & Voss Ha 137 competed as a private venture.^[3]

The Ar 81 was the only one of the competitors to be conceived as a biplane. Reportedly this was on the advice of Ernst Udet. There seems to have been some doubt at Arado about the use of this outdated configuration, for alternative designs were made for a monoplane with an inverted gull wing.^[2] However, in the end the Ar 81 was built as an all-metal biplane. It was a neat enough design, which looked rather more streamlined than the first prototype of the Ju 87, and was slightly smaller and lighter. The slender fuselage had a closely cowled Junkers Jumo 210C engine up front with a large radiator bath below it. The wings were relatively short in span and connected by N-struts outboard. Behind the wings, the crew of two sat in a roomy cockpit in with a semi-enclosed canopy, back to back. The rear of the cockpit canopy was open to allow the gunner to freely aim his defensive machine gun. The fixed main landing gears legs were fitted with streamlined covers and spats for the wheels.

The tail section was very slender, and the tail of the first prototype, Ar 81V1, consisted of a tailplane with some dihedral that carried two outboard fins and rudders, to improve the field of fire of the tail gunner. However, testing from the end of 1935 onward revealed serious stability problems.^[3] The second prototype was given a raised tailplane without dihedral, braced with struts, but this did not cure the issues, and the third prototype had completely reworked tail, with a boom structure of larger cross-section that carried a tall single tail fin and a large rudder. This prototype also had a Jumo 210Ca engine that drove a two-bladed variable-pitch propeller, instead of the three-bladed fixed-pitch unit fitted to the first two prototypes.^[1]

The defensive armament of a single fixed MG 17 machine gun, intended to be fitted in the engine cowling, and a MG 15 defensive gun in the rear cockpit, was probably never installed. The same is claimed for the special bomb rack below the fuselage, intended to swing a 250 kg bomb clear of the propeller in a diving attack.^[1] However, test pilot Kurt Starck claimed that during the 1936 trials, the Ar 81 was the only aircraft capable of dropping a 500 kg bomb in a vertical dive, which indicates that a bomb rack must have been fitted.^[2]

In its developed Ar 81V3 form, the Arado design was in several aspects better than the Ju 87 prototypes, including level speed, manoeuvrability, range, and especially rate of climb: It reached 4000 m in 11 minutes, while the Junkers design needed 23 minutes.^[2] However, the Ju 87 was a more modern design and its performance could be improved by installing more powerful engines, while the Ar 81 had less development potential. Due to the delay involved in redesigning the tail, the Ar 81V3 only made its appearance in the spring of 1936, when the RLM had already chosen the Ju 87.^[1]^[3]

Specifications (Ar 81V3)

Data from Herbert Léonard^[1]

General characteristics

Crew: 2
Length: 11.65 m (38 ft 2½ in)
Wingspan: 11.20 m (36 ft 9 in)
Height: 3.57 m (11 ft 8½ in)
Wing area: 35.6 m² (383 sq.ft)
Empty weight: 1,925 kg (4,235 lb)
Loaded weight: 3,070 kg (6,754 lb)
Powerplant: 1 × Junkers Jumo 210Ca, 640 hp at 2700 m (477 kW)
Propellers: 1 propeller, 1 per engine

Performance

Maximum speed: 345 km/h (186 knots, 214 mph) at 4,000 m (13,100 ft)
Range: 790 km (427 nmi, 491 mi)
Service ceiling: 7,700 m (25,300 ft)
Climb to 4,000 m (13,100 ft): 11 minutes

Armament

Guns:
- 1 × 7.92 mm MG 17 fixed in the engine cowling,
- 1 × 7.92 mm MG 15 flexible in the rear cockpit
Bombs: 1 × 250 kg bomb on a bomb crutch under the fuselage

References

1 2 3 4 5 Herbert Léonard, Stukas! - Les Avions Allemands d'attaque au sol (1933-1945), Editions Heimdal, France 1997.
1 2 3 4 Jörg Armin Kranzhoff, Arado-Flugzeuge Vom Doppeldecker zum Strahlflugzeug, Bernard & Graefe Verlag, Germany 2001.
1 2 3 Peter C. Smith, Dive Bomber!, Naval Institute Press, USA, 1982.

Aircraft produced by Arado Flugzeugwerke

Ar 64 Ar 65 Ar 66 Ar 67 Ar 68 Ar 69 Ar 76 Ar 79 Ar 80 Ar 81 Ar 95 Ar 96 Ar 195 Ar 196 Ar 197 Ar 198 Ar 199 Ar 231 Ar 232 Ar 233 Ar 234 Ar 240 Ar 296 Ar 396 Ar 432 Ar 440 Ar 532 E.340 E.377 E.380 E.381 E.500 E.530 E.555 E.560 E.561 E.580 E.581 E.583 L I L II S I SC I SC II SD I SD II SD III SSD I V I W 2

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

This article is issued from Wikipedia - version of the 7/26/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.