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fuselage, three-blade propeller, and a canopy over the cockpits. The aircraft appeared with a variety of tail units, the final version (five built) designated O-31A featured a very pointed fin with an inset rudder. The single YO-31B was an unarmed staff transport and the sole YO-31C converted from
142:. A contract was signed on January 7, 1930 for two XO-31 prototype aircraft, the first of them being flown in December of the same year. A fabric-covered gull-wing monoplane, the XO-31 had a slim corrugated dural-wrapped fuselage, similar to the
153:
The XO-31 suffered from directional instability and experiments were made with various fins, auxiliary fins, and rudder shapes, in an effort to cure the problem. The second aircraft was completed as the YO-31, with a geared
167:
YO-31A had cantilever main landing gear, and a ventral bulge in the fuselage, which enabled the observer to operate his single 0.3-in (7.62 mm) machine-gun more effectively from a standing position.
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Anxious to retain its position as chief supplier of observation aircraft to the USAAC, Douglas developed a proposal for a high-wing monoplane successor to the
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propeller. Four YO-31A aircraft delivered during early 1932 were modified radically with an elliptical wing planform, a new tail assembly, a smooth
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Editors: Paul Eden & Soph Moeng, (Amber Books Ltd. Bradley's Close, 74-77 White Lion Street, London, NI 9PF, 2002,
174:. They differed from the final configuration of the O-31A, with a wire-braced parasol wing, and a new fin and rudder.
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Five Y1O-31C service-test aircraft were ordered in 1931, and delivered to the USAAC in early 1933 designated
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structure of flat sheets, length increased to 33 ft 11 in (10.34 m), Curtiss V-1570-53 engine
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429:"United States Military Aircraft Since 1909" by F. G. Swanborough & Peter M. Bowers (Putnam New York,
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McDonnell
Douglas aircraft since 1920 : Volume I, United States military aircraft since 1909
208:
revised XO-31, length increased to 33 ft 5 in (10.19 m), Curtiss V-1570-7 engine
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V-12 engine and fixed landing gear with provision for large wheel fairings.
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five built, wingspan increased to 45 ft 11 in (14 m), became the
526:
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engine and an enlarged fin, 3" longer cowling, and a two-blade,
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one built, re-designated O-31B, Curtiss V-1570-29 engine
502:(Revised ed.). London: Putnam. pp. 231–233.
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195 mph (314 km/h, 169 kn) at sea level
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McDonnell
Douglas aircraft since 1920 : Volume I
230:
YO-31A with cantilever gear, Curtiss V-1570-53 engine
1799:
1930s United States military reconnaissance aircraft
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477:. London: Naval Institute Press. pp. 111–118.
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357:10,000 ft (3,000 m)7 minutes 12 seconds
16:US military observation aircraft introduced 1930
126:observation straight-wing aircraft used by the
451:"The Complete Encyclopedia of World Aircraft"
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498:Swanborough, F. G.; Bowers, Peter M. (1971).
8:
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500:United States military aircraft since 1909
388:1 fixed and 1 flexible 0.30 cal (7.62 mm)
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333:160 mph (260 km/h, 140 kn)
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339:260 mi (420 km, 230 nmi)
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7:
290:339.9 sq ft (31.58 m)
278:45 ft 11 in (14.00 m)
272:34 ft 5 in (10.49 m)
413:"U.S. Army Aircraft 1908-1946" by
186:"U.S. Army Aircraft 1908-1946" by
14:
372:0.12 hp/lb (0.20 kW/kg)
351:1,515 ft/min (7.70 m/s)
27:
1804:Single-engined tractor aircraft
1:
345:22,700 ft (6,900 m)
310:Curtiss GIV-1570-FM Conqueror
302:4,982 lb (2,260 kg)
296:3,888 lb (1,764 kg)
148:Curtiss GIV-1570-FM Conqueror
1814:Aircraft first flown in 1930
473:Francillon, René J. (1988).
128:United States Army Air Corps
68:United States Army Air Corps
200:Curtiss V-1570-25 Conqueror
1830:
240:, Curtiss V-1570-53 engine
156:Curtiss V-1570-7 Conqueror
1632:(Nightingale/Skytrain II)
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26:
120:Douglas Aircraft Company
58:Douglas Aircraft Company
257:General characteristics
245:Specifications (YO-31C)
1809:Parasol-wing aircraft
1608:C-124 Globemaster II
1316:Boston I/II/III/IV/V
960:Related designations
917:Tri-Service sequence
589:USAAC/USAAF sequence
569:observation aircraft
390:Browning machine gun
1134:A-4SU Super Skyhawk
39:General information
1130:A-4AR Fightinghawk
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1780:
1768:D-558-2 Skyrocket
1763:D-558-1 Skystreak
1725:Training aircraft
1658:R4D-1/-3/-5/-6/-7
1623:C-133 Cargomaster
1507:(Dakota I/III/IV)
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95:Introduction date
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197:
194:
193:
192:
190:, 1946, 64pp.
189:
185:
177:
175:
173:
168:
165:
164:semimonocoque
161:
157:
151:
149:
145:
141:
133:
131:
129:
125:
121:
117:
108:
105:
101:
97:
93:
89:
85:
80:
76:
72:
69:
66:
62:
59:
56:
54:
50:
46:
42:
37:
30:
25:
20:
1773:X-3 Stiletto
1751:Experimental
1361:
1277:Model 1211-J
1247:B-26 Invader
1186:AD Skyraider
1106:A-26 Invader
747:
499:
493:
474:
468:
385:
377:
375:
366:
360:
354:
348:
342:
336:
330:
324:
317:
315:
305:
299:
293:
287:
281:
275:
269:
263:
256:
254:
249:
248:
183:
181:
169:
152:
137:
116:Douglas O-31
115:
113:
107:Douglas O-43
87:Manufactured
74:Number built
64:Primary user
53:Manufacturer
1700:Skymaster I
1340:Observation
1242:B-23 Dragon
1201:A4D Skyhawk
1126:A-4 Skyhawk
991:Unconfirmed
591:(1924–1942)
581:Tri-Service
463:), 1152 pp.
318:Performance
312:(V-1570-53)
306:Powerplant:
198:two built,
134:Development
47:Observation
1788:Categories
1448:Transports
1326:Havoc I/II
1065:F4D Skyray
509:0370000943
484:0870214284
396:References
368:Power/mass
288:Wing area:
184:Data from:
1272:Model 423
1227:B-18 Bolo
532:Aerofiles
276:Wingspan:
250:Data from
124:monoplane
122:'s first
90:1930-1933
1038:Fighters
378:Armament
178:Variants
118:was the
1709:Gliders
1321:Digby I
1210:Bombers
1030:Douglas
583:systems
282:Height:
270:Length:
233:Y1O-31C
82:History
1716:XCG-17
1695:PD.808
1685:CC-129
1613:YC-129
1596:C-117D
1586:YC-116
1581:XC-114
1406:Patrol
506:
481:
459:
433:
337:Range:
238:Y1O-43
227:YO-31C
221:YO-31B
211:YO-31A
202:engine
172:Y1O-43
1742:XT-30
1663:R4D-8
1618:C-132
1603:C-118
1591:C-117
1571:C-110
1551:UC-67
1495:C-41A
1475:YC-34
1397:YOA-5
1382:YO-44
1309:DB-73
1304:DB-19
1252:XB-31
1237:XB-22
1232:XB-19
1222:YB-11
1050:XP-48
977:OV-12
972:OV-10
577:USAAF
573:USAAC
453:cover
386:Guns:
264:Crew:
205:YO-31
195:XO-31
33:XO-31
1737:BT-2
1732:BT-1
1690:LXD1
1636:C-24
1566:C-84
1556:C-68
1546:C-58
1531:C-52
1526:C-51
1521:C-50
1516:C-49
1511:C-48
1500:C-42
1490:C-41
1485:C-39
1480:C-38
1470:C-33
1465:C-32
1460:C-21
1392:O-53
1387:O-46
1377:O-43
1372:O-38
1367:O-35
1362:O-31
1331:DXD1
1299:DB-8
1294:DB-7
1289:DB-2
1284:DB-1
1217:YB-7
1156:XT3D
1111:A-33
1101:A-24
1096:A-20
1091:XA-2
1055:P-70
967:OV-1
908:O-63
903:O-62
898:O-61
893:O-60
888:O-59
883:O-58
878:O-57
873:O-56
868:O-55
863:O-54
858:O-53
853:O-52
848:O-51
843:O-50
838:O-49
833:O-48
828:O-47
823:O-46
818:O-45
813:O-44
808:O-43
803:O-42
798:O-41
793:O-40
788:O-39
783:O-38
778:O-37
773:O-36
768:O-35
763:O-34
758:O-33
753:O-32
748:O-31
743:O-30
738:O-29
733:O-28
728:O-27
723:O-26
718:O-25
713:O-24
708:O-23
703:O-22
698:O-21
693:O-20
688:O-19
683:O-18
678:O-17
673:O-16
668:O-15
663:O-14
658:O-13
653:O-12
648:O-11
643:O-10
579:and
504:ISBN
479:ISBN
457:ISBN
431:ISBN
114:The
98:1930
44:Type
22:O-31
1678:R6D
1668:R5D
1653:R3D
1648:R2D
1630:C-9
1455:C-1
1439:F-3
1423:P3D
1418:P2D
1357:O2D
1347:O-2
1151:T2D
1045:XFD
951:O-6
946:O-5
941:O-4
936:O-3
931:O-2
926:O-1
638:O-9
633:O-8
628:O-7
623:O-6
618:O-5
613:O-4
608:O-3
603:O-2
598:O-1
140:O-2
1790::
1673:JD
1643:RD
1413:PD
1352:OD
1171:BD
1146:DT
442:^
422:^
404:^
308:×
130:.
77:13
1132:/
1128:/
1022:e
1015:t
1008:v
575:/
560:e
553:t
546:v
512:.
487:.
370::
266:2
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