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164:(S/N 30-281) was converted to Y1B-4 configuration with the addition of R-1860-7 radial engines and low pressure tires. Because of more powerful engines, the performance of the Y1B-4 was a slight improvement on the B-3, but the only difference between the two planes was their engines. On April 28, 1931, the army ordered 25 improved Y1B-4s as the
168:. This production version was part of the last biplane bomber order made by the Army Air Corps (along with 39 B-6As, identical in all respects except their make of engine), and the B-4As, delivered between January and April 1932, were the last biplane bombers delivered to the Air Corps.
176:
The B-4 was the last of the
Keystone biplane bombers ordered by the U.S. Army in late 1931. These aircraft were used primarily as observation and reconnaissance aircraft as early as 1934 when the
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went into operational service. Some remained in service into the early 1940s.
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designation was dropped in 1930, the first five planes were redesignated
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2,500 lb (1,100 kg); 4,000 lb (1,800 kg) on short runs
192:
Seven aircraft ordered but delivered as the Y1B-4 and
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446:List of military aircraft of the United States
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817:
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500:
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366:11.31 lb/sq ft (55.22 kg/m)
256:Keystone B-4A in flight in the Philippines
216:Production version of the Y1B-4, 25 built.
348:850 mi (1,400 km, 760 nmi)
336:130 mph (210 km/h, 110 kn)
132:
840:bomber designations, Army/Air Force and
342:103 mph (167 km/h, 90 kn)
251:
247:
206:but with two 575 hp (429 kW)
1528:
171:
798:
481:
202:Five pre-production aircraft, as the
1556:Twin piston-engined tractor aircraft
295:1,145 sq ft (106.4 m)
196:with different engine installations.
1546:1930s United States bomber aircraft
277:48 ft 10 in (14.9 m)
13:
283:74 ft 8 in (22.8 m)
14:
1567:
458:Encyclopedia of American Aircraft
451:
289:15 ft 9 in (4.8 m)
227:
27:
307:12,952 lb (5,875 kg)
1:
513:Keystone and Keystone-Loening
360:580 ft/min (30 m/s)
354:14,000 ft (4,300 m)
301:7,951 lb (3,607 kg)
473:USAF Museum article on LB-13
242:United States Army Air Corps
220:
208:Pratt & Whitney R-1860-7
139:United States Army Air Corps
127:United States Army Air Corps
78:United States Army Air Corps
7:
1483:Fighter-bomber, in F-series
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33:Keystone Y1B-4 (S/N 30-281)
10:
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468:USAF Museum article on B-4
315:Pratt & Whitney R-1860
137:Originally ordered by the
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16:American bomber aircraft
441:List of bomber aircraft
375:0.0888 hp/lb (146 W/kg)
321:, 575 hp (429 kW) each
262:General characteristics
145:light bomber. When the
257:
133:Design and development
1462:Redesignated A-series
391:3 Ă— .30 in (7.62 mm)
255:
248:Specifications (B-4A)
1432:Tri-Service sequence
725:Observation aircraft
413:Related development
172:Operational history
39:General information
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435:Related lists
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364:Wing loading:
362:
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340:Cruise speed:
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305:Gross weight:
303:
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299:Empty weight:
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235:United States
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166:Keystone B-4A
163:
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961:Heavy bomber
925:
859:Light bomber
648:
623:
434:
433:
429:Keystone B-6
424:Keystone B-5
419:Keystone B-3
412:
411:
400:
396:machine guns
388:
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378:
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351:
345:
339:
333:
326:
324:
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261:
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178:Martin B-10B
175:
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159:
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146:
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136:
112:Keystone B-4
111:
109:
103:Keystone B-3
84:Number built
74:Primary user
55:Manufacturer
48:Light bomber
1406:(1935–1936)
993:(1930–1962)
852:(1924–1930)
842:Tri-Service
509:Huff-Daland
327:Performance
311:Powerplant:
1530:Categories
779:Pathfinder
463:Photograph
371:Power/mass
293:Wing area:
160:The first
769:Air Yacht
281:Wingspan:
221:Operators
1551:Biplanes
774:Commuter
668:Trainers
515:aircraft
408:See also
393:Browning
381:Armament
210:engines.
184:Variants
844:systems
562:Bombers
287:Height:
275:Length:
153:. (The
141:as the
116:biplane
94:History
89:25 B-4A
87:5 Y1B-4
69:Retired
1495:FB-111
1323:RB-57F
1318:RB-57D
1192:NB-36H
784:Pronto
401:Bombs:
346:Range:
232:
119:bomber
114:was a
66:Status
1504:Other
1490:FB-22
1423:BLR-3
1418:BLR-2
1413:BLR-1
1276:B-50C
1254:B-47C
1187:B-36G
1145:B-29D
931:LB-14
926:LB-13
921:LB-12
916:LB-11
911:LB-10
834:USAAF
830:USAAC
826:USAAS
762:Names
732:XO-15
639:XHB-1
629:LB-14
624:LB-13
619:LB-12
614:LB-11
609:LB-10
579:XLB-3
574:XLB-1
528:HD.8A
389:Guns:
269:Crew:
204:LB-10
199:Y1B-4
194:Y1B-6
189:LB-13
151:Y1B-4
143:LB-13
1511:B-21
1474:B-26
1469:B-20
1395:B-71
1390:B-70
1385:B-69
1380:B-68
1375:B-67
1370:B-66
1365:B-65
1360:B-64
1355:B-63
1350:B-62
1345:B-61
1340:B-60
1335:B-59
1330:B-58
1313:B-57
1308:B-56
1303:B-55
1298:B-54
1293:B-53
1288:B-52
1283:B-51
1271:B-50
1266:B-49
1261:B-48
1249:B-47
1244:B-46
1239:B-45
1234:B-44
1229:B-43
1224:B-42
1219:B-41
1214:B-40
1209:B-39
1204:B-38
1199:B-37
1182:B-36
1177:B-35
1172:B-34
1167:B-33
1162:B-32
1157:B-31
1152:B-30
1140:B-29
1135:B-28
1130:B-27
1125:B-26
1120:B-25
1115:B-24
1110:B-23
1105:B-22
1100:B-21
1095:B-20
1090:B-19
1085:B-18
1080:B-17
1075:B-16
1070:B-15
1065:B-14
1060:B-13
1055:B-12
1050:B-11
1045:B-10
978:HB-3
973:HB-2
968:HB-1
906:LB-9
901:LB-8
896:LB-7
891:LB-6
886:LB-5
881:LB-4
876:LB-3
871:LB-2
866:LB-1
838:USAF
753:XS2L
695:AT-2
690:AT-1
685:TW-5
680:TA-6
675:TA-2
634:XB-1
604:LB-9
599:LB-8
594:LB-7
589:LB-6
584:LB-5
569:LB-1
553:K-85
548:K-84
543:K-78
538:K-55
533:K-47
313:2 Ă—
213:B-4A
162:B-3A
155:Y1B-
110:The
44:Type
1446:B-2
1441:B-1
1040:B-9
1035:B-8
1030:B-7
1025:B-6
1020:B-5
1015:B-4
1010:B-3
1005:B-2
1000:B-1
952:B-2
947:B-1
737:XOK
659:B-6
654:B-5
649:B-4
644:B-3
317:-7
147:LB-
22:B-4
1532::
716:PK
700:NK
511:,
129:.
836:/
832:/
828:/
818:e
811:t
804:v
501:e
494:t
487:v
373::
271:5
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