By the mid twenties rivalry between the U.S. Army Air Service and the Navy was at its height, and the Air Service made repeated attempts to keep in the public eye and favour. It pioneered the U.S. Air Mail service at great cost in lives and air¬craft, and made many long distance flights and record attempts. In July 1923, U.S. Army Air Service disclosed that it intended to attempt a global flight the following year. Four specially built two seat Douglas World Cruisers were used for this last achievement, each powered by a 400 hp Liberty engine and with interchangeable wheel and float undercarriages for the over land and over water sectors. As far as structure was concerned, the DWC was identical to the DT-2. The internal equipment, however, was specially designed for the round-the-world attempt and the saving in weight by deletion of the military load (torpedo with release gear, firing sight, etc) was used to increase the range of the aeroplane to 3,540km by fitting extra petrol and oil tanks – totalling 2,437.8 litres.
The all-up weight (floats) was 3,710kg. The improved engine, a 313kW Liberty, offered a weight of less than 0.91kg per hp.
Wings: Sitka Spruce, Cotton Covering
Fuselage: Steel Tube, Sitka Spruce, Cotton Covering
Empennage: Sitka Spruce, Cotton Covering
Cowling: Aluminum
Named after the cities of Seattle, Chicago, Boston and New Orleans, the four aircraft took off from Lake Washington, Seattle, on April 6. 1924 Seattle hit a mountainside in Alaska. After completing much of the journey, Boston force landed in the Atlantic, the other two arrived back at Seattle on September 28, after a 27,534 mile flight over 28 countries. It took 175 days, with a flying time of 371 hours 11 minutes. Throughout the journey the crews prevailed against an endless series of forced landings, repairs, bad weather, and other mishaps that continually threatened the success of the flight.

The crews were; Alva L.Harvey, Leigh Wade, Erik Nelson, Kailua-Kona, John J. Harding, Henry H. Ogden, Frederick L. Martin, Lowell H. Smith, and Leslie P. Arnold.

Douglas World Cruiser Around the World Article

DWC Landplane
Engine: Liberty, 400 hp / 313kW
Wingspan: 15.24 m / 50 ft 0 in
Length: 10.82 m / 35 ft 6 in
Height: 4.14 m / 13 ft 7 in
Wing area 65.68 sq.m / 707 sq. ft
Empty weight 1950 kg / 4,300 lb
Loaded weight 3137 kg / 6,915 lb
Max. speed 166 km/h / 103 m.p.h
Cruise speed: 85 km/h / 53 mph
Ceiling 3050 m / 10,000 ft
Range 3540 km / 2,200 miles.
Crew: 2

DWC Seaplane
Engine: Liberty, 400 hp / 313kW
Wingspan: 15.24 m / 50 ft 0 in
Length: 10.82 m / 35 ft 6 in
Height: 4.14 m / 13 ft 7 in
Wing area 65.68 sq.m / 707 sq. ft
Empty weight 5,100 lb
Loaded weight 7,715 lb
Max. speed 100 m.p.h
Ceiling 7.000 ft
Range 1,650 miles.
Crew: 2

The US Post Office Department had been responsible for US internal air mail routes from 1918 onwards, and by 1925 the various types of DH-4 biplane which had been primary equipment since inception of the service were worn out. A decision was thus made to order a conversion of the Douglas O-2 observation biplane, which had been ordered into quantity production for the US Army.
The Douglas DAM-1 (Douglas Air Mail-One), quickly shortened to M-1, was test flown during the spring of 1925. It had twice the payload of the DH-4, but made use of the same Liberty engine, of which large numbers were in store and readily available. The M-1 was a straightforward conversion of the O-2, with the forward cockpit covered in sheet aluminium to form a reinforced mail compartment with access through two deck hatches, the pilot being located in what was formerly the rear (observer’s) cockpit in the O-2. During tests, extended exhaust piping was installed to keep fumes away from the pilot. The M-1 was adjudged successful, but no production order was received by Douglas.

With the introduction of Contract Air Mail (CAM) routes, however, the newly formed Western Air Express Company (later Western Airlines) ordered six Douglas mailplanes. Designated M-2, they differed from the M-1 mainly by replacement of the original tunnel radiator with a frontal type. Provision was also made for quick conversion of the freight section to permit carriage of a passenger in place of mail. A month before Western Air Express inaugurated its Los Angeles-Salt Lake City service in April 1926, the US Post Office ordered 50 of the M-3 version for its major routes. The M-3s differed only in detail from the M-2s, sporting an overall aluminium finish with US Air Mail emblazoned in black on the fuselage sides and on the undersurfaces of the lower wing. Western’s machines had a red and silver paint scheme.
The Douglas Company’s chief engineer, J. H. ‘Dutch’ Kindelberger, then redesigned the M-3 with the aim of doubling its payload. The main change in this new M-4 was an entirely new ‘stretched’ wing which spanned 1.47m more than the 12.09m of the earlier types, and lacked the cut-out in the trailing edge of the upper wing inherited from the US Army O-2s. The Post Office was sufficiently impressed to arrange for 40 of the 50-plane M-3 order to be delivered in M-4 configuration. A single M-4 bought by Western Air Express was designated M-4A by Douglas to differentiate it from the Post Office order. With the leasing of route CAM-3 (Chicago-Dallas) to National Air Transport (NAT) in October 1925, a need arose for more mailplanes. NAT at first used the Curtiss Carrier Pigeon and then, having acquired the important Chicago-New York route, bought at auction all 10 M-3s and eight M-4s from the Post Office when, during July 1926, that department relinquished all its routes to private operators.
The Douglas mailplanes were introduced by NAT on 1 September 1927, and were phased out during 1930 in favour of three-engined Ford tri-motors. In their three years’ service they performed admirably in all weathers and in the most difficult flying conditions. NAT had bought other M-4s from a variety of sources and at one stage had as many as 24 Douglas mailplanes in operation. Among them was a privately owned aircraft which had been confiscated by the US Treasury while illegally smuggling liquor from Cuba to Florida during Prohibition; it became known as the ‘Booze Ship’. NAT M-3s were flown with new long-span wings from the spring of 1928 onwards; for economic reasons these had been designed and constructed by the company’s own engineering department. One M-4 was converted by NAT to take a 391kW Pratt & Whitney Hornet radial engine.
A total of 57 Douglas mailplanes was built, but with the advent of the Ford and other three-engined types they were soon withdrawn from air mail services. A few were sold to private owners but the majority were scrapped.

M-4
Engine: 1 x Liberty 12 V-12 piston engine, 298kW
Max take-off weight: 2223 kg / 4901 lb
Loaded weight: 1544 kg / 3404 lb
Wingspan: 13.56 m / 44 ft 6 in
Length: 8.81 m / 28 ft 11 in
Height: 3.07 m / 10 ft 1 in
Wing area: 38.18 sq.m / 410.97 sq ft
Max. speed: 225 km/h / 140 mph
Cruise speed: 177 km/h / 110 mph
Ceiling: 5030 m / 16500 ft
Range: 1127 km / 700 miles

Douglas dropped anchor in Santa Monica with Davis’ money and began work on the Cloudster, an airplane that contained some innovative uses of streamlining, then a new design construction. The Navy gave him an order for three of the airplanes, but it wasn’t until Los Angeles Times publisher Harry Chandler rounded up some local financial support that Douglas was able to get going. A single example of a Liberty-powered biplane was built for an attempt at a non-stop flight across the USA.

Engine: 1 x Liberty, 295kW
Max take-off weight: 4354 kg / 9599 lb
Empty weight: 2177 kg / 4799 lb
Wingspan: 17.0 m / 55 ft 9 in
Length: 11.2 m / 36 ft 9 in
Height: 3.7 m / 12 ft 2 in
Max. speed: 193 km/h / 120 mph
Cruise speed: 137 km/h / 85 mph
Range w/max.fuel: 4345 km / 2700 miles
Crew: 2

Designed by Etienne Dormoy in 1919 as a single place open cockpit biplane experiment in ultralights. A basic framework with wings and a pilot’s seat behind the 18hp Henderson motor. The idea was carried over into Dormoy Bathtub.

Flown successfully at Selfridge Field, Detroit, only the one was built, sometimes listed as a Packard Motor Co product but actually spare-time project by Dormoy and his co-workers while employed there.