TECHNICAL SPECIFICATIONS (NO-1)
Type: Three- place observation landplane or floatplane.
Manufacturer: Naval Aircraft Factory, Philadelphia, Pennsylvania; Glenn L. Martin Co., Cleveland, Ohio.
Total produced : 6 (USN)
Powerplant: One 350-hp Curtiss D 12-cylinder water- cooled inline en- gine driving a two- bladed fixed- pitch wooden propeller. Armament: One flexible .30-cal. Lewis machine gun in the rear cock-
pit.
Performance: Max. speed 103 mph at s.1.; ceiling 11,200 ft.; range 490 mi.
Weights: 3,337 lbs. empty, 4,842 lbs. loaded.
Dimensions: Span 43 ft. 6 in., length 31 ft. 10 in., wing area 462 sq. ft. A more conservative approach to the three- place observa- tion requirement than the preceding Martin MO-1, the NO arose
One of six MS-1s delivered for trials in 1923. MS-1 and XS-1 were identical except for type of airframe materials. Exercises with submarine S-1 continued until late 1926, when further testing was deemed impractical.
Martin M2O-1
The NAF NO-1 in pictured in 1923 or 1924. M2O and NO were both powered by Curtiss D-12 engines and identical except for small details. Note W-types struts in place of usual rigging wires.
from a BuAer design in which construction contracts were as- signed to both NAF and Martin during 1923 for three aircraft each. While the identity of the designer is not recorded any- where, the NO/M2O incorporated a structural design using W- type and N- type struts very similar to those of the TS fighter designed by Rex Beisel in 1921. Martin’s M2O-1 was the first to fly, sometime in 1923, and all of six ordered had been deliv- ered before the end of 1924. The chief differences between the NAF and Martin versions appear to have been a spinner, indi- vidual exhaust stacks, and a slightly taller fin and rudder ap- pearing on the M2O-1. One NAF aircraft retrofitted with a 440- hp Packard 1A-1500 engine was tested as
the NO-2, but no performance details were reported. Not placed in quantity produc- tion, the type served at various shore de- tachments until withdrawn in 1926 and 1927.
Loening OL, HL—1923
TECHNICAL SPECIFICATIONS (OL-2 [OL-9])
Type: Three- place military observation and util- ity amphibian.
Manufacturer: Loening Aeronautical Engineer- ing Co., New York, New York
Total produced: 160 (USN, USMC, USCG) Powerplant: one 400-hp Liberty 12-cylinder
water- cooled engine driving a four-bladed wooden fixed- pitch propeller [one 450-hp Pratt & Whitney R-1340-4 Wasp 9-cylinder air- cooled radial engine driving a three- bladed ground- adjustable propeller]. Armament: one flexible .30-caliber Lewis ma-
chine gun in the rear cockpit, [one fixed .30-caliber machine in the upper wing; and four 114-lb. bombs on wing racks]. Performance: max. speed 121 mph [122 mph];
ceiling 12,100 ft. [14,300 ft.]; range 405 mi. [625 mi.].
Weights: 3,540 lbs. [3,469 lbs.] empty, 5,010 lbs. [5,404] loaded.
Dimensions: span 45 ft. 0 in., length 33 ft. 10 in. [34 ft. 19 in.], wing area 500 sq. ft. [502 sq. ft].
When the first examples appeared in 1923, Grover C. Loening’s “shoehorn” se- ries of observation and utility planes were really flying boat–floatplane hybrids in which the upper fuselage faired into a main float that extended all the way aft to support the tail group. This novel configu- ration, similar in many respects to that of his civil Flying Yacht of 1921, was con- ceived by Loening out of an desire to offer an amphibian whose performance would match a landplane having an engine of similar horsepower. The manually operated
landing gear used a system of sprockets and chains to retract into the main float. The original prototype was delivered to the Army in 1923 as the XCOA-1 (the C was later dropped) and nine production models followed in 1924. A Navy prototype powered by a 440-hp Packard engine and having a third cockpit was delivered in 1925 as the XOL-1. The same year, the Navy ac - quired five Liberty- powered OA-1s, placing them in service as OL-2s to be used in the 1925 Arctic Expedition, and four essen - tially identical aircraft were purchased from Loening as OL-3s. The first of six OL-4s, which differed in having a reshaped and balanced rudder, revised cowling, and three- bladed metal pro-
peller was delivered in early 1926. These were followed by three very similar OL-5s, which bore the distinction of being the first aircraft ordered specifically for use by the Coast Guard.
Flown in late 1926, the OL-6 came with a 475-hp Packard V-12 engine and a third cockpit, and twenty- six production ex- amples were delivered from early to mid–1927. During the same timeframe, twenty- four very similar OA-1As and Bs were also produced for the Army, followed by ten OA-1Cs with reshaped tails. As the wingspan of the OLs was too large to enable them fit onto the deck elevators of the Navy’s new aircraft carriers, one OL-6 modified in mid–1927 with a smaller wing and a thicker airfoil section was tested in mid–1927 as the XOL-7, but its performance proved to be disappointing and no produc- tion resulted. In late 1927, after BuAer specified that all future naval aircraft would be equipped with air- cooled engines, Loen- ing modified the Last OL-6 to accept installation of an R-1340
Wasp radial engine and delivered it as the XOL-8. After trials,
twenty production models were delivered during 1928 as the OL-8, followed in 1929 by twenty nearly identical OL-8As. Eight OA-2s, similar to OL-8As except for 480-hp Wright V- 1640 V-12 water- cooled engines, were delivered to the Army the same year.
The final version, the OL-9, which differed from the OL-8
in having a fixed .30-caliber machine in the upper wing and underwing racks for four 114-lb. bombs, was produced during 1931 and 1932 after Loening had been acquired by Keystone, and the last of 26 built accepted by the Navy in March 1932. Two airframes similar to the OL-8, completed as ambulance
Top: An OL-2, one of five Army OA-1s transferred to the Navy
in 1925 to be used in the Arctic Expedition. The novel “shoehorn” configuration and gear-fold mechanism made OLs one of the first practical military amphibians. Middle: Introduced in 1926, the OL-6 featured a third cockpit and a 475-hp Packard engine driving a three-bladed propeller. Most were assigned to battle- ships for utility and observation duties. Bottom: All OL-9s were built between 1931 and 1932 after Loening had been acquired by Keystone. This aircraft is depicted in its later career serving in the Naval Reserve at NRAB Oakland, California, in 1937. Leoning OL-8
planes with a cabin occupying the space behind the pilot’s cockpit, were delivered to the Navy in 1929 as XHL-1s, with one assigned to the Marines. As newer Grum- man JF Ducks began arriving during the mid–1930s, OL-8s and 9s were phased out of active service, with the final OL-9 being withdrawn by the end of 1937.
Douglas OD—1926
TECHNICAL SPECIFICATIONS (OD-1) Type: Two- place observation landplane. Manufacturer: Douglas Aircraft Co., Santa
Monica, California. Total produced : 2 (USMC)
Powerplant: One 439-hp Liberty V-1650-1 12- cylinder water- cooled inline engine driving a two- bladed fixed- pitch wooden propeller.
Armament: One flexible .30-cal. Lewis ma - chine gun in the rear cockpit.
Performance: Max. speed 126 mph at s.1.; ceiling 12,275 ft.; range 606 mi.
Weights: 2,941 lbs. empty, 4,630 lbs. loaded.
Dimensions: Span 39 ft. 8 in., length 29 ft. 6 in., wing area 411 sq. ft.
As the O-2, a single- bay biplane of mixed construction that utilized a surplus Liberty powerplant, this aircraft became the Army’s standard observation type during the mid– and late 1920s. In 1926, two O-2Cs, which differed from earlier versions in having a nose- mounted radiator and split- axle landing gear, were delivered to the Marine West Coast Expeditionary Force in San Diego and taken into service as the OD-1. Both examples operated with VO-8M until being replaced by Curtiss OC-2s (F8C-3s) in early 1930, and were used for utility duties until withdrawn from service altogether in 1931.
Vought O2U—1926
TECHNICAL SPECIFICATIONS (O2U-1 SEAPLANE) Type: Two- place observation landplane or floatplane.
Manufacturer: Chance Vought Corp., Long Island City, New York. Total produced : 291 (USN, USMC, USCG)
Powerplant: One 450-hp Pratt & Whitney R-1340-88 Wasp 9-cylinder air- cooled radial engine driving a two- bladed ground- adjustable Hamilton- Standard metal propeller.
Armament: One fixed forward- firing .30-cal. machine gun and one flexible .30-caliber machine gun in the rear cockpit.
Performance: Max. speed 127 mph at s.1.; ceiling 18,700 ft.; range 571 mi.
Weights: 2,600 lbs. empty, 3,893 lbs. loaded.
Dimensions: Span 34 ft. 6 in., length 28 ft. 7 in., wing area 320 sq. ft. The first of the “Corsair” series, the O2U represented a serious effort by the Navy to upgrade its observation fleet with a newer aircraft that incorporated recent structural and aero- dynamic improvements. After issuing requirements, BuAer awarded Vought a contract in mid–1926 to design and build two aircraft for evaluation as the O2U-1. In line with recent BuAer policy, the new type was developed around Pratt & Whitney’s new 450-hp R-1340 Wasp engine, and though no arresting gear had been specified, overall dimensions were small enough to enable it to fit onto the deck elevators of the new carriers. The first prototype, flown on November 2, 1926, featured a spinner Two OD-1s were procured for the Marines in 1926 and served alongside the DH-4Bs and O2B-1 of VO-8M until replaced by OC-2s in 1929. The plane was similar to the Army’s O-2 and was used briefly as utility hacks.
and straight- axle landing gear, but the second prototype, with no spinner and split- axle gear, formed the basis for 130 O2U-1 production models ordered in early 1927.
As deliveries proceeded, O2U-1s became the fleet’s standard floatplane aboard battleships, serving as detach- ments of VO-3B, VO-4B, and VO-5B, and a small number, rigged as landplanes and fitted with arresting gear, served with VS-1B aboard Langley. Ten O2U-1 landplanes also were assigned to Marine units, six to VO-7M in Nicaragua and four to VO-9M in Haiti. Thirty- seven O2U-2s com - pleted in 1928 with an 18-inch increase in upper wingspan and factory- installed arresting gear served exclusively in VS units aboard the Navy’s three carriers. The fleet’s grow- ing need for floatplanes generated new orders for 80 O2U- 3s and 42 O2U-4s (minor differences in equipment) deliv- ered in 1929 and 1930, which both featured revised tail surfaces and the larger upper wing of the O2U-2. The
phase- out of O2U floatplanes with newer types began as early as 1931, but many continued in various utility roles until the last examples were withdrawn from Navy service during 1937. Nine ex–Navy O2U-2s allocated to the Coast Guard in 1934 and 1935 served longer, the last not being withdrawn until 1941.