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201:. When the Post Office retired its aircraft in July 1926 after all the routes had been privatized, NAT bought ten M-3s and eight M-4s at auction. NAT bought other aircraft and at one point had a fleet of 24 Douglas mailplanes in use. Some of the NAT M-3s were modified by them with longer-span wings from 1928 onwards. One M-4 was re-engined by NAT with a
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175:. The main change from the M-1 was that the tunnel radiator was replaced with a frontal type. It also had the provision to carry a passenger instead of mail in the front cockpit. Just before Western Air Express introduced the aircraft into service (in April 1926 from Los Angeles to Salt Lake City), the Post Office ordered 50 aircraft designated
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engine as the DH.4, which was available in large numbers. Small modifications were made to the exhaust system to keep fumes away from the pilot and the design was considered a success, but was not ordered into production.
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observation biplane. The company modified an O-2 by covering over the forward cockpit to make a mail compartment and moving the pilot into what had been the observer's cockpit. The aircraft was designated the
186:. The M-4 had a new longer span wing and the Post Office converted some of the M-3s order to be built as M-4s. One M-4 was also bought by Western Air Express and this was designated the
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radial engine. With the introduction of three-engined aircraft types beginning in 1928, the
Douglas mailplanes were withdrawn from service; some were sold but most were scrapped.
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biplane. In 1925, it decided to modernize and placed an order with
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Douglas then redesigned the M-3 to try to increase the payload, and the new aircraft was designated the
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The
Illustrated Encyclopedia of Aircraft (Part Work 1982-1985), 1985, Orbis Publishing, Page 1574
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McDonnell
Douglas aircraft since 1920 : Volume I, The Illustrated Encyclopedia of Aircraft
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for its major route network. The M-3 had only detailed differences from the M-2.
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Modified mailplane with stretched wing for United States Post Office.
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A three-seat general purpose biplane developed directly from the
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197:(NAT) in October 1925, the airline originally used the
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140 mph (230 km/h, 120 kn) at sea level
147:(Douglas Air-Mail-One) but this was soon shortened to
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McDonnell
Douglas aircraft since 1920 : Volume I
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When the CAM-3 (Chicago-Dallas) route was passed to
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272:series of mailplanes, despite the O-2 designation.
242:Production mailplane for United States Post Office
456:. London: Naval Institute Press. pp. 85–89.
253:Douglas M-4 photo from L'Année aéronautique 1926
163:(CAM) routes were introduced, the newly formed
171:) ordered six mailplanes with the designation
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226:Production mailplane for Western Air Express
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407:700 mi (1,100 km, 610 nmi)
478:The Illustrated Encyclopedia of Aircraft
401:110 mph (180 km/h, 96 kn)
493:"The Incomplete Guide to Airfoil Usage"
480:. Orbis Publishing. 1985. p. 1574.
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763:MD-91X / -92X / -94X
425:10.5 lb/sq ft (51 kg/m)
217:Prototype mailplane modified from the
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520:McDonnell Douglas Aircraft since 1920
434:0.0813 hp/lb (0.1337 kW/kg)
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347:44 ft 6 in (13.56 m)
341:28 ft 11 in (8.81 m)
753:188 / 188E / 210
353:10 ft 1 in (3.07 m)
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359:465 sq ft (43.2 m)
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419:1,000 ft/min (5.1 m/s)
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814:Single-engined tractor aircraft
262:One M-4 for Western Air Express
804:1920s United States mailplanes
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413:16,500 ft (5,000 m)
380:4,900 lb (2,223 kg)
374:3,405 lb (1,544 kg)
824:Aircraft first flown in 1925
452:Francillon, René J. (1988).
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773:High Speed Civil Transport
203:Pratt & Whitney Hornet
195:National Air Transport Inc
122:designed and built by the
93:National Air Transport Inc
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303:United States Post Office
85:United States Post Office
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151:. The M-1 used the same
124:Douglas Aircraft Company
522:. London:Putnam, 1979.
497:m-selig.ae.illinois.edu
326:General characteristics
728:DC-7 (C-74 derivative)
298:National Air Transport
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234:Douglas M-3 at Langley
199:Curtiss Carrier Pigeon
114:are a family of 1920s
47:Single-seat mailplanes
548:at Wikimedia Commons
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768:MD-12 / -XX
738:DC-8 piston airliner
518:Francillon, René J.
314:Specifications (M-4)
785:McDonnell 119 / 220
308:Western Air Express
165:Western Air Express
89:Western Air Express
81:Primary users
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491:Lednicer, David.
161:Contract Air Mail
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100:Number built
721:Never built
675:Jet-engined
546:Douglas M-2
386:Performance
219:Douglas O-2
140:Douglas O-2
130:Development
120:mail planes
18:Douglas M-2
798:Categories
783:See also:
758:Model 2229
748:DC-10 Twin
463:0870214284
439:References
430:Power/mass
357:Wing area:
588:airliners
345:Wingspan:
319:Data from
277:Operators
159:When the
819:Biplanes
502:16 April
209:Variants
116:American
621:Dolphin
582:Douglas
368:Clark Y
364:Airfoil
351:Height:
339:Length:
153:Liberty
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405:Range:
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733:DC-7D
712:MD-11
707:DC-10
702:MD-95
697:MD-90
692:MD-80
646:DC-4E
333:Crew:
265:MO-2B
145:DAM-1
76:1926
68:1925
44:Role
687:DC-9
682:DC-8
666:DC-7
661:DC-6
656:DC-5
651:DC-4
641:DC-3
636:DC-2
631:DC-1
584:and
524:ISBN
504:2019
458:ISBN
259:M-4A
188:M-4A
110:The
616:M-4
611:M-3
606:M-2
601:M-1
245:M-4
239:M-3
223:M-2
214:M-1
184:M-4
177:M-3
173:M-2
149:M-1
104:57
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