MILITARY AIRCRAFT by Jos Heyman

Air Force

O = Observation (1924-1942)

Last update: 1 February 2015

O-1 Curtiss 37 Falcon

Specifications: span: 38'. 11.58 m length: 27'9", 8.46 m engines: 1 Curtiss V-1150 max. speed: 143 mph, 230 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3375)

Based on the Falcon series of aircraft, the XO-1 was fitted with a Liberty V-1650-1 engine and had a length of 28'7", 8.71 m. A single example was built with serial 23-1252 and was entered in the 1924 and 1925 design competitions. It was later fitted with a Packard 1A-1500. Eventually it was redesignated as ZXO-1. The first production version was the O-1, to which the specifications apply. 10 aircraft were ordered with serials 25-325/334. Of these aircraft 25-333 was converted with a Liberty V-1650-3 engine and was redesignated as O-1A . It was also known as XO-1A. 25 examples of the O-1B version were ordered with serials 27-263/287. They were basically similar to the O-1 but had a V-1150-5 engine and a length of 27'3", 8.31 m. Those remaining in service were eventually redesignated as ZO-1B . Four aircraft were converted as O-1C as staff transports with side by side seating in the rear cockpit. They had serials 27-264, 27-266/268. Those remaining in service were eventually redesignated as ZO-1C. A projected version of the O-1C, to be known as the O-1D , was to have a V-1150-7 engine but was not built. The O-1E version had a length of 28'4", 8.64 m and a V-1150-5 engine. 36 were built with serials 29-282/287 and 29-289/318 whilst a batch with serials 29-319/322 was converted to YO-13C and Y1O-26 before completion. In addition an A-3B with serial 30-001 was converted to this standard. One aircraft, with serial 29-288 was ordered as O-1E but was completed as the O-1F unarmed communications aircraft. One O-1E with serial 29-295, was tested as XBT-4 and yet later converted as XO-1G as Curtiss model 38. It was later redesignated as Y1O-G and eventually as O-1G . In addition 30 O-1Gs were built with serials 31-472/501. These were similar to the O-1E but had a length of 27'4", 8.33 m. Those remaining in service were eventually redesignated as ZO-1G. Several aircraft were flown with Wright Field serial numbers: 23-1252 as P-375, 25-325 as P-437, 25-333 as P-449, 25-334 as P-440, 27-267 as P-558, 27-268 as P-497, 27-276 as P-532, 27-277 as P-596, 29-282 as P-587 and an unknown aircraft as P- 484.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-11, O-12, O-13, O-16, O-18, O-26, O-39, F8C

O-2 Douglas

Specifications: span: 39'8", 12.09 m length: 29'7", 9.02 m engines: 1 Packard 1A-1500 max. speed: 150 mph, 241 km/h

(Source: Pat Loop, via 1000aircraftphotos.com photo #5378)

Based on the US Navy’s DT design a single XO-2 prototype was tested with both a long and a short span and was initially fitted with a Liberty V-1650-1 before the 1A-1500 engine was installed. It had a length of 29'3", 8.92 m. The serial was 23-1251. Some reference sources have suggested that the Dayton Wright XO-3 with serials 23-1254 was also an XO-2. The initial production version was the O-2, to which the specifications apply. 46 were built with serials 25-335/380 whilst O-7s with serials 25-406 and 25-407 were also converted to this standard. The O-2A version was fitted for night flying but was otherwise similar to the O-2, 18 were built with serials 25-387/404. O-2As with serials 25-405/407 were completed as O-7. In addition an O-2A with serial 25-408 was converted to O-8 before being converted back to O-2A. Finally, O-2C 25-409, which had been converted to O-9, was also converted to the O-2A standard. After having provisionally been designated as XO-2B , six O-2B dual control aircraft were built with serials 25-381/386. The O-2C version incorporated various improvements and 33 were built with serials 26-386/418 and 25-409. Also O-7 25-405 was converted to this standard. One of the aircraft, with serial 26-387 was used for experimental purposes with designation XO-2C . The designation O-2D was assigned to an unarmed staff transport and two were built with serials 26-419/420. In 1927 a single O-2C with serial 26-418, was fitted with a different tail arrangement and was redesignated as XO-2E . On completion of tests it was redesignated as O-2E . The O-2F and O-2G designations were reserved for projected versions which were cancelled. The O-2H version had a span of 40', 12.19 m, a length of 30', 9.14 m, a Liberty V-1650-1 engine and a max. speed of 133 mph, 214 km/h. 141 were built of this version with serials 27-288/297, 28-128/187, 28-349/358, 29-158/178, 29-342/351 and 29-375/404. One of these aircraft, 29-164, was later converted as O-25. Another aircraft was flown as XO-2H . A staff transport version of the O-2H was designated as O-2J and three were built with serials 28-127, 28-188 and 29-209. The O-2K version was based on the O-2H but had minor improvements. 59 were built with serials 29-179/208, 29-210/218 and 29-413/432. 40 of these were later converted to BT-1. The O-2M version was supplied to Mexico and was not ordered through US military agencies. Several aircraft were flown with Wright Field serials: 23-1251 as P-374, 23-1251 as P-519, 25-350 as P-441, 25-353 as P-465, 26-387 as P-458, 26-418 as P-466 and unknown aircraft P-467, P-468, P-481, P-482, P-492, P-512, P-514, P-521, P-525 and P-529.

Refer also to A-2, BT-1, BT-2, O-7, O-8, O-9, O-14, O-22, O-25, O-29, O-32, O-34, O-38, OD

O-3 Dayton Wright

Specifications: span: 45', 13.72 m length: 31', 9.45 m engines: 1 Wright V-1950 max. speed: 146 mph, 235 km/h

(Source: D. Abel, via Aerofiles.com)

One XO-3 was ordered with serial 23-1254. It was also flown with Wright Field serial P-376 but was returned to the manufacturer on 30 April 1925, presumably cancelled. Some references show this as a Wright design. It seems that after the demise of Dayton Wright, the XO-3 was completed by . Other reference sources have suggested that 23-1254 was a Douglas XO-2.

O-4 Martin 71

Specifications: span: length: engines: 1 Liberty V-1650-1 max. speed:

One XO-4 was ordered with serial 23-1255 but was subsequently cancelled.

O-5 Douglas

Specifications: span: 50', 15.24 m length: 38'11", 11.86 m engines: l Liberty V-1650-1 max. speed: 107 mph, 172 km/h

(Source: TKnl, via Aerofiles.com)

Based on the DT design, six XO-5s were ordered as Douglas Observation Seaplane (DOS) but were designated as O-5 before delivery. The serials were 24-002/007.

O-6 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 28'8", 8.74 m engines: 1 Liberty V-1650-1 max. speed: 129 mph, 208 km/h

(Source: USAAC McCook)

The XO-6 was a metal version of the O-2 design and two were built against an order which had been placed on 21 April 1926. The serials were 25-435/436 and they were also flown with Wright Fields serials P-439 and P-456 respectively. Three examples of the O-6 were built with serials 25-437/439. Whilst the O-6A designation was not assigned, the XO-6B designation was used for an extensively redesigned version with a Pratt & Whitney R-1340 engine. Although the aircraft, with serial 25-440, was not accepted, it was tested with Wright Field serial P-503 and eventually evolved into the O-19 design.

Refer also to O-2, O-19

O-7 Douglas

Specifications: span: 39'8", 12.09 m length: 29'6", 8.99 m engines: 1 Packard 1A-1500 max. speed: 137 mph, 220 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3405)

Three O-2As were completed as O-7. Of these two were later further converted to O-2 standards and one to O-2C standards. The serials of these aircraft were 25-405/407. Aircraft 25-405 and 25-407 were also flown with Wright Field serials P-432 and P-459 respectively. 25-405 was eventually converted as an O-2C whilst 25-406 and 25-407 were converted to O-2 standards. Some reference sources claim that only one aircraft (25-409) was involved.

Refer also to A-2, BT-1, O-2, O-8, O-9, O-14, O-22, O-25, O-29, O-32, O-34, O-38, OD

O-8 Douglas

Specifications: span: 39'8", 12.09 m length: 28'8", 8.74 m engines: 1 Curtiss R-1454 max. speed: 108 mph, 190 km/h

(Source: Dan Shumaker, via 1000aircraftphotos.com photo #9137)

A single O-2A was fitted with a different engine and was redesignated as O-8. It had serial 25-408 and was also flown with Wright Field serial P-455. It was later converted back to O-2A configuration.

Refer also to A-2, BT-1, O-2, O-7, O-9, O-14, O-22, O-25, O-29, O-32, O-34, O-38, OD

O-9 Douglas

Specifications: span: 39'8", 12.09 m length: 31', 9.45 m engines: 1 Packard 1A-1500 max. speed: 131 mph, 221 km/h

(Source: TKnL, via Aerofiles.com)

A single O-2C, with serial 25-409, was temporarily fitted with a different engine as O-9. It was also flown with Wright Field serial P-448 and was later converted back to O-2A. Some reference sources state the serial 25-405.

Refer also to A-2, BT-1, O-2, O-7, O-8, O-14, O-22, O-25, O-29, O-32, O-34, O-38, OD

O-10 Loening

Specifications: span: 46'3", 14.10 m length: 35', 10.67 m engines: 1 Wright V-1460-1 max. speed: 110 mph, 177 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3409)

The single XOA-1A was redesignated as XO-10 before delivery. It had serial 26-212 and Wright Field serial P-566 and some reference sources have suggested it was first converted as XAO-2. Other references suggest that XOA-1A 24-008 was converted and designated as XOA-2 before it was further converted as XO-10. The XO-10 was scrapped in September 1930 after 32 flying hours.

Refer also to OA-1

O-11

Specifications: span: 38', 11.58 m length: 28'4", 8.64 m engines: 1 Liberty V-1650-3 max. speed: 142 mph, 228 km/h

(Source: US Army NG)

A single O-1, with serial 25-328, and a single O-11, with serial 27-098, were used as the XO-11 prototypes. They had a length of 27'4", 8.33 m. The O-11 , to which the specifications apply, was the main production version and 66 were built with serials 27-001/035, 27-098/107 and 28-197/217. Many of these aircraft were subject of further conversions. One such conversion was that to O-11A , which had a length of 28'6", 8.69 m and had dual controls for use by the Customs Dept. on the Mexican border. It had serial 27-001. Several aircraft were also flown with Wright Field serials: 25-328 as P-476, 27-098 as P-487, 28-200 as P-585, 28-216 as P- 583 and unknown aircraft P-478 and P-518.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-12, O-13, O-16, O-18, O-26, O-39

O-12 Curtiss Falcon

Specifications: span: 38', 11.58 m length: 27'9", 8.46 m engines: 1 Pratt & Whitney R-1340-1 max. speed: 139 mph, 224 km/h

(Source: USAAF?)

A single O-11 with serial 27-035, was converted as XO-12 .

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-11, O-13, O-16, O-18, O-26, O-39

O-13 Curtiss Falcon

Specifications: span: 38', 11.58 m length: 28'4", 8.64 m engines: 1 Curtiss V-1570-1 max. speed: 164 mph, 264 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3383)

In 1927 a single O-1 with serial 25-332, was converted as the XO-13 for the races that year. It was also flown with Wright Field serial P-489 and was scrapped in 1928. In a similar way, O-1 25-331 was converted for the same races as XO-13A , differing from the XO-13 in minor details only. It was also flown with Wright Field serial P-495. The O-13B designation was used for an O-1C which had been converted. The serial was 27-266. The YO-13C version had a length of 27'6", 8.38 m and three O-1Es, with serials 29-319/321 were converted and were later redesignated as O-13C . The YO-13D , with serial 28-207, were converted to this standard. The YO-13D had previously been converted from an O-11 by fitting a Curtiss SV-1570 engine. It had a length of 28'4", 8.64 m and, after having been converted to YO-13C was further converted to O-1B standards.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-11, O-12, O-16, O-18, O-26, O-39

O-14 Douglas

Specifications: span: 30'1", 9.17 m length: 23'10", 7.26 m engines: 1 Wright R-790-5 max. speed: 121 mph, 195 km/h

(Source: USAF)

The XO-14 was a scaled down version of the O-2H and one was built with serial 28-194. It was also flown with Wright Field serial P-539.

Refer also to A-2, BT-1, O-2, O-7, O-8, O-9, O-22, O-25, O-29, O-32, O-34, O-38, OD

O-15 Keystone

Specifications: span: 37'3", 11.35 m length: 27'1", 8.26 m engines: 1 Wright R-790-5 max. speed: 119 mph, 191 km/h

(Source: USAAF?)

The XO-15 was a two seat bi-plane of which one was built with serial 28-195. It was also flown with Wright Field serial P-531.

O-16 Curtiss

Specifications: span: 38', 11.58 m length: 27'6", 8.38 m engines: 1 Curtiss V-1570-9 max. speed: 161 mph, 259 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3376)

The single XO-16 was an O-11 modified using design features of the XA-5. The serial was 28-196.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-11, O-12, O-13, O-18, O-26, O-39

O-17 Consolidated Courier

Specifications: span: 34'6", 10.52 m length: 28', 8.53 m engines: 1 Wright R-790-1 max. speed: 103 mph, 166 km/h

(Source: USAF)

Based on the PT-3 design, a single PT-3 was in April 1927 converted as XO-17 . It had serial 28-229 and was also flown with Wright Field serial P-510. This was followed by 29 O-17 production aircraft with serials 28-360/385, 28-396/397 and 30-089. The XO-17A was a version with a R-790-3 engine which was originally ordered as PT-3 and was later converted to XPT-8. The serial was 28-317 and it was also flown with Wright Field serial P-513.

Refer also to BT-6, BT-7, T-1, T-2, T-3, T-4, T-5, T-6, T-8, T-11, T-12, NY, N4Y

O-18 Curtiss Falcon

Specifications: span: 38', 11.58 m length: 27'4", 8.33 m engines: 1 Curtiss H-1640-1 max. speed: 148 mph, 238 km/h

(Source: USAF)

A single O-1B, with serial 27-263, was converted as XO-18 . It was also flown with Wright Field serial P-515.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-11, O-12, O-13, O-16, O-26, O-39

O-19 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 28'4", 8.64 m engines: 1 Pratt & Whitney R-1340-7 max. speed: 152 mph, 245 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3408)

A single XO-19 was ordered on 16 June 1928 with serial 28-400. It had a length of 28'6", 8.69 m and was fitted with a R-1340-3 engine. This was followed by two O-19 service test aircraft with serials 28-401 and 29-369 which had R-1340-9 engines. A similar aircraft, designated O-19A and with serial 29-370, was also built. The O-19B designation, to which the specifications apply, was assigned to 70 production aircraft which had been ordered on 16 August 1929 with serials 30-090/159. One of these, 30-091, was used for tests and was redesignated as XO-19B . The next order, placed on 12 June 1930, was for 71 O-19C s with serials 31-278/348. These had a length of 29', 8.84 m. One of these aircraft, 31-279, was converted as a staff transport and was redesignated as O-19D . It had a span of 40', 12.19 m, length of 28'10", 8.79 m and a R-1340-15 engine. Eventually O-19Cs and O-19Ds remaining in service were redesignated as ZO-19C (including serials 31-319, 31-320, 31-327, 31-328, 31-330, 31-331 and 31-333) and ZO-19D . The O-19E version was similar to the O-19D and 30 were built against an order which had been placed in February 1931. The serials were 31-523/552. Eventually those remaining in service were redesignated as ZO-19E . Serials included 31-528, 31-529, 31-531, 31-534, 31-551 and 31-552. Several aircraft were also flown with Wright Field serials: 28-401 as P-543, 29-370 as P-569 and 30-081 as P-598.

Refer also to O-6, O-20, O-21, O-23, O-33

O-20 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 29', 8.84 m engines: 1 Pratt & Whitney R-1690-1 max. speed: 147 mph, 237 km/h

(Source: San Diego Air and Space Museum)

Based on the O-19 design, a single YO-20 was ordered on 20 December 1928 with serial 28-402. It was also flown with Wright Field serial P-561.

Refer also to O-6, O-19, O-21, O-23, O-33

O-21 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 29'2", 8.89 m engines: 1 Curtiss H-1640-1 max. speed: 152 mph, 245 km/h

(Source: USAF via Aerofiles.com)

The XO-21 was a development of the O-19 design and one aircraft was ordered on 20 December 1928 with serial 28-403. It was also flown with Wright Field serial P-575. Later it was fitted with a Wright R-1750-1 engine, giving it a length of 28'7", 8.71 m, and was redesignated as XO-21A .

Refer also to O-6, O-19, O-20, O-23, O-33

O-22 Douglas

Specifications: span: 38'1", 11.61 m length: 28'4", 8.64 m engines: 1 Pratt & Whitney R-1340-9 max. speed: 142 mph, 228 km/h

(Source: David Horn, via 1000aircraftphotos.com photo #8906)

The O-22 was an experimental aircraft with swept upper wings. Three aircraft were ordered as O-22 with serials 29-371/373 and have also been referred to as YO-22 and ZO-22 . The third aircraft was later converted to YO-34. One aircraft was flown with Wright Field serial P-577.

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-25, O-29, O-32, O-34, O-38, OD

O-23 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 28'10", 8.79 m engines: 1 Curtiss V-1570-1 max. speed: 156 mph, 251 km/h

(Source: Consolidated)

Based on the O-19 design, one YO-23 was ordered on 3 November 1928 with serial 29-352. It was also flown with Wright Field serial P-562.

Refer also to O-6, O-19, O-20, O-21, O-33

O-24 Curtiss

Specifications: span: length: engines: 1 Pratt & Whitney R-1340-7 max. speed:

This two seat project, designated O-24 , was not proceeded with.

O-25 Douglas

Specifications: span: 40', 12.19 m length: 30'8", 9.35 m engines: 1 Curtiss V-1570-5 max. speed: 158 mph, 254 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3401)

A single O-25 was ordered with serial 30-160. It was also flown with Wright Field serial P-560 and was later converted with a V-1570-27 engine and redesignated as XO-25A . In addition O-2H 29-164 was converted as an O-25 and was flown with Wright Field serial P-538. It was later also redesignated as XO-25A. The first production version was the O-25A of which 49 were ordered with serials 30-161/195 and 30-354/370. Of these 31-161/163 were completed as O-25B dual control staff transports, leaving only 46 aircraft completed as O-25A. Eventually those O-25As and O-25Bs remaining in service were redesignated as ZO-25 and ZO-25B . The next version was the O-25C which had a length of 31'4", 9.55 m. 30 were built with serials 32-181/210.

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-22, O-29, O-32, O-34, O-38, OD

O-26 Curtiss Falcon

Specifications: span: 38', 11.58 m length: 27'6", 8.38 m engines: 1 Curtiss V-1570-11 max. speed: 167 mph, 269 km/h

(Source: RMP Archive, via 1000aircraftphotos.com photo #3107)

The Y1O-26 was a converted O-1E airframe with serial 29-322. The designation XO-26 has also been applied to this aircraft and, on completion of testing it was redesignated as O-26 . It remained in use until August 1934.

Refer also to A-3, A-4, A-5, A-6, BT-4, O-1, O-11, O-12, O-13, O-16, O-18, O-39

O-27 Fokker 16

Specifications: span: 64'7", 19.69 m length: 47'6", 14.48 m engines: 2 Curtiss V-1570-29 max. speed: 177 mph, 285 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3514)

Two XO-27 s were ordered with serials 29-327/328. Of these only 29-328 was completed as XO-27 with a span of 64', 19.51 m, length of 47'7", 14.43 m and V-1570-9 engines. Aircraft 29-327 was fitted with V-1570-29 engines and was completed as XO-27A . The specifications apply to the YO-27 version of which six were built with serials 31-587/592. On completion of testing these were redesignated as O-27 . The designation ZYO-27 was also used. The Y1O-27 designation was assigned to two YB-8s and four Y1B-8s which were redesignated before delivery and had serials 31-598/603. These were also eventually redesignated as O-27 as well as ZO-27 .

Refer also to B-8

O-28

Specifications: span: 34'6", 10.52 m length: 24'6", 7.47 m engines: 1 Pratt & Whitney R-1340-C max. speed: 150 mph, 241 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3593)

A single US Navy O2U-3 was evaluated by the USAAC as XO-28 and with serial 29-323 and Wright Field serial P-547. The aircraft was destroyed on 18 March 1930.

Refer also to O2U

O-29 Douglas

Specifications: span: 40', 12.19 m length: 30'8", 9.35 m engines: 1 Wright R-1750-1 max. speed: 141 mph, 227 km/h

(Source: USAAF?)

A single O-2K, with serial 29-184, was re-engined and redesignated as Y1O-29 . It was also flown with Wright Field serial P- 576. Later it was fitted with a Wright R-1820-1 engine and redesignated as Y1O-29A , before being further redesignated as O-29A . Eventually it was redesignated as ZO-29A .

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-22, O-25, O-32, O-34, O-38, OD

O-30 Curtiss

Specifications: span: length: engines: 2 Curtiss V-1570-9 max. speed:

One example of the XO-30 monoplane observation aircraft was ordered with serial 29-451 but it was subsequently cancelled.

O-31 Douglas

Specifications: span: 45'8", 13.92 m length: 33'2", 10.11 m engines: 1 Curtiss V-1570-25 max. speed: 176 mph, 283 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3400)

A gull winged monoplane, two XO-31 prototypes were ordered in January 1930 with serials 30-229 and 30-230. The first aircraft was completed as XO-31 and flew for the first time in December 1930. Ultimately it was redesignated as ZXO-31 . Aircraft 30-230 was completed as YO-31 with a length of 33'5", 10.91 m and a V-1570-7 engine. It was ultimately redesignated as ZYO-31 . The YO-31A version had a V-1570-53 engine and a length of 33'11", 10.34 m. Five were ordered with serials 31-604/608. On completion of testing they were redesignated as O-31A whilst the designation ZYO-31A has also been quoted. The Y1O-31A version was similar except for a span of 45'11", 14.00 m. Five aircraft were ordered in August 1931 with serials 32-291/295 but were redesignated as Y1O-31C , only to be converted as Y1O-43s at a later date. One YO-31B was ordered with serial 32-231. It was fitted with a V-1570-29 engine and was used as an unarmed staff transport. Later it was redesignated as O-31B and ZO-31B . The YO-31C designation was used for a single O-31A converted to Y1O-31C standards. It had serial 31-608. Eventually it was redesignated as O-31C and ZO-31C .

Refer also to O-43, O-46, O-48

O-32 Douglas

Specifications: span: 40', 12.19 m length: 31'2", 9.50 m engines: 1 Pratt & Whitney R-1340-3 max. speed: 133 mph, 214 km/h

(Source: USAF)

A single O-2K, with serial 29-218, was converted to O-32 standards. It was also flown with Wright Field serial P-568. Later it was further converted to BT-2 standards. It had a length of 30'9", 9.37 m. The production version was the O-32A of which 30 were built with serials 30-196/225. Later they were converted to BT-2A. One of the O-32As was also flown with Wright Field serial P-591.

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-22, O-25, O-29, O-34, O-38, OD

O-33 Thomas Morse

Specifications: span: 39'9", 12.12 m length: 29'2", 8.89 m engines: 1 Curtiss V-157-11 max. speed: 165 mph, 265 km/h

(Source: USAAF?)

In August 1930 a single O-19B was converted with a new engine and tail surfaces and was redesignated as Y1O-33 . The serial was 30-090.

Refer also to O-6, O-19, O-20, O-21, O-23

O-34 Douglas

Specifications: span: 38'1", 11.61 m length: 29', 8.84 m engines: 1 Curtiss V-1570-11 max. speed: 156 mph, 251 km/h

A single O-22 was converted as YO-34 , sometimes referred to as XO-34 . The serial was 29-373.

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-22, O-25, O-29, O-32, O-38, OD

O-35 Douglas

Specifications: span: 65'3", 19.89 m length: 45'6", 13.87 m engines: 2 Curtiss V-1570-29 max. speed: 178 mph, 286 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3451)

A single XO-35 was ordered on 26 March 1930 with serial 30-227 although some reference sources claim that aircraft 30-228, which was completed as XO-36, was also originally ordered as XO-35. The XO-35 was eventually redesignated as ZXO-35 . This was followed by five Y1O-35 s with serials 32-315/319 and V-1570-53 engines. On completion of testing these were redesignated as O-35 .

Refer also to B-7, O-36

O-36 Douglas

Specifications: span: 65', 19.81 m length: 45'6", 13.87 m engines: 2 Curtiss V-1570-25 max. speed: 169 mph, 272 km/h

One XO-36 was ordered on 26 March 1930 with serial 30-228 although some reference sources claim it was initially ordered as XO-35. The aircraft was, however, completed as XB-7.

Refer also to B-7, O-35

O-37 Keystone/Loening

Specifications: span: 44'11", 13.69 m length: 35', 10.67 m engines: 1 Pratt & Whitney R-1340-9 max. speed:

Based on the OA-2, a single XO-37 that had been ordered with serial 30-396 was cancelled before completion.

Refer also to OA-2

O-38 Douglas

Specifications: span: 40', 12.19 m length: 31'3", 9.53 m engines: 1 Pratt & Whitney R-1690-3 max. speed: 143 mph, 230 km/h

(Source: USAF)

The O-38 observation aircraft was the ultimate development of the O-2 design. 46 were ordered with serials 30-407/419, 31-349/379 and 31-406/407. One of these, 30-407, was converted as the O-38A unarmed staff transport. The O-38B version had a R-1690-5 engine and a length of 32', 9.75 m. 63 were built with serials 31-409/438, 32-102/116 and 32-325/342. The O-38C designation was used for an aircraft fitted with a R-1690-7 engine and, although ordered by the USAAC with serial 32-394, it was used by the USCG with its serial 9 and later V108. The O-38D version had a span of 40'3", 12.27 m, a length of 31'10", 9.70 m and a Wright R-1820-1 engine. One aircraft was built with serial 33-001, which was followed by 37 O-38E s which were similar except for a Pratt & Whitney R-169013 engine. The serials of the O-38E were 33-002/016 and 34-001/022. Of these 34-001/022 had originally been ordered with serials 33- 298/319. The O-38F version was similar to the O-38E but had a R-1690-9 engine. Eight were built with serials 33-322/329. Eventually aircraft remaining in service were redesignated as ZO-38 , ZO-38A , ZO-38B , ZO-38D and ZO-38E . The designations O-38S and O-38P refer to a company development and a direct ordered version for .

Refer also to A-2, BT-1, BT-2, O-2, O-7, O-8, O-9, O-14, O-22, O-25, O-29, O-32, O-34, OD

O-39 Curtiss Falcon

Specifications: span: 38', 11.58 m length: 27', 8.23 m engines: 1 Curtiss V-1570-25 max. speed: 173 mph, 278 km/h

(Source: David Horn, via 1000aircraftphotos.com photo #9434)

Ten O-39 s were built with serials 32-211/220. Some were later fitted with enclosed cockpits. Eventually those remaining in service were redesignated as ZO-39 .

Refer also to A-3, A-4, A-5, A-6, O-1, BT-4, O-11, O-12, O-13, O-16, O-18, O-26

O-40 Curtiss 62 Raven

Specifications: span: 44', 13.41 m length: 28'10", 8.79 m engines: 1 Wright R-1820-37 max. speed: 190 mph, 3065 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3406)

The two seater Raven observation aircraft began its life as a sesquiplane with a span of 44'4", 13.51 m, length of 28'6", 8.69 m and a Y1R-1820-F engine. It was designated as YO-40 and had serial 32-343. The aircraft crashed on 20 May 1932 and was subsequently rebuilt as YO-40A , to which the specifications apply. On completion of testing it was redesignated as O-40A and eventually as ZYO-40A . The Y1O-40A was a monoplane version with a span of 41'8", 12.70 m and four were ordered with serials 32-415/418 although they were delivered as Y1O-40B in June 1933. On completion of tests they were redesignated as O-40B .

O-41 Thomas Morse

Specifications: span: 40'8", 12.40 m length: 29'3", 8.92 m engines: 1 Curtiss V-1570-29 max. speed: 191 mph, 307 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3407)

Based on the O-33, a single Y1O-41 was tested at Wright Field in June 1931 after a first flight on 4 May 1931. It did not receive a serial and was also referred to as XO-932 .

Refer also to O-33

O-42 Thomas Morse

Specifications: span: --- length: engines: --- max. speed: ---

The Y1O-42 was a high wing monoplane design of which only a fuselage was built for static tests. It was completed in 1932 and was also referred to as XO-924 . No serial was assigned.

O-43 Douglas

Specifications: span: 45'11", 14.00 m length: 34'4", 10.46 m engines: 1 Curtiss V-1570-59 max. speed: 191 mph, 307 km/h

(Source: William T. Larkins)

The five Y1O-31Cs, which had serials 32-291/295, were fitted with parasol wings and were redesignated as Y1O-43 . They had a length of 33'11", 10.34 m and a V-1570-53 engine. On completion of testing they were redesignated as O-43 in 1933. The O-43A was the production version of which 24 were ordered with serials 33-268/291. The last aircraft was converted as XO-46 whilst in 1933 the others were also redesignated as O-43.

Refer also to O-31, O-46, O-48

O-44 Douglas

Specifications: span: 89'9", 27.36 m length: 69'9", 21.26 m engines: 2 Pratt & Whitney R-1690-11 max. speed:

The XB-11 amphibian was redesignated as YO-44 before delivery and was again redesignated as YOA-5, although some reference sources claim that the YOA-5 designation was assigned before the YO-44 designation. The serial of the aircraft was 33-017.

Refer also to B-11, OA-5, P3D

O-45 Martin

Specifications: span: 70'6", 21.49 m length: 44'8", 13.61 m engines: 2 Wright R-1820-17 max. speed: 200 mph, 322 km/h

A version of the B-10 design, a single YB-10 was temporarily tested in 1934 as the YO-45 . A production version was designated as O-45 but was cancelled.

Refer also to A-15, B-10, B-12, B-13, B-14

O-46 Douglas

Specifications: span: 45'9", 13.94 m length: 34'10", 10.62 m engines: 1 Pratt & Whitney R-1535-7 max. speed: 200 mph, 322 km/h

(Source: National Museum of the Air Force)

A single O-43A with serial 33-291, was converted as the XO-46 prototype. It had a span of 45'11", 14.00 m, a length of 33'10". Eventually it was redesignated as ZXO-46 . It was followed by 90 production O-46A s which were ordered from 29 April 1935 and to which the specifications apply. The serials were 35-161/231, 36-128/144 and 36-147/148. Those remaining in service in 1942 were redesignated as RO-46A .

Refer also to O-31, O-43, O-48

O-47 North American

Specifications: span: 46'6", 14.12 m length: 33'3", 10.13 m engines: 1 Wright R-1820-49 max. speed: 225 mph, 362 km/h

(Source: National Museum of the Air Force)

Originally designed by General Aviation as GA-15 and first flown as NX2079, the aircraft was procured by the USAAC after General Aviation had been taken over by North American. The aircraft was designated as XO-47 and given serial 36-145. It had a length of 33'6", 10.21 m and a R-1820-41 engine. Eventually it was redesignated as ZXO-47 . The production version, to which the specifications apply, was designated as O-47A and 164 were built with serials 37-260/368 and 38-271/325. This was followed by the O-47B version which had a R-1820-57 engine and of which 74 were built with serials 39-065/138.

O-48 Douglas

Specifications: span: 45'9", 13.94 m length: 35'2", 10.72 m engines: 1 Wright R-1670-3 max. speed:

In 1936 the XO-46, which had serial 33-291, was to be re-engined as XO-48 but this project was cancelled.

Refer also to O-31, O-43, O-46

O-49 Stinson 74 Vigilant

Specifications: span: 50'11", 15.52 m length: 33'2", 10.11 m engines: 1 Lycoming R-680-9 max. speed: 129 mph, 208 km/h

(Source: USAF)

Although designed by Stinson, the Vigilant was built by Vultee. 142 examples of the O-49 were ordered from 20 September 1939 with serials 40-192/291 and 40-3101/3142. The first flight took place on 15 July 1940 and those aircraft remaining in service in April 1942 (or possibly earlier) were redesignated as L-1. The O-49A version had a length of 34'3", 10.44 and 182 aircraft were ordered with serials 41-18900/19081. In April 1942 they were redesignated as L-1A. Four O-49s were converted as O-49B ambulances and were redesignated as L-1B April in 1942.

Refer also to CQ-2, L-1

O-50 Bellanca

Specifications: span: 55'6", 16.92 m length: 35'2", 10.72 m engines: 1 Ranger V-770-1 max. speed: 120 mph, 193 km/h

(Source: Jack Fisher, via 1000aircraftphotos.com photo #9800)

Three YO-50 s were ordered with serials 40-741/743 but further production was cancelled due to cost escalations and complexity.

O-51 Ryan Dragonfly

Specifications: span: 52', 15.85 m length: 34'5", 10.49 m engines: 1 Pratt & Whitney R-985-21 max. speed: 130 mph, 209 km/h

(Source: Curtis Aldrich, via 1000aircraftphotos.com photo #9155)

Three YO-51 s were built with serials 40-703/705.

O-52 Curtiss 85 Owl

Specifications: span: 40'4", 12.29 m length: 26'7", 8.10 m engines: 1 Pratt & Whitney R-1340-51 max. speed: 208 mph, 335 km/h

(Source: National Museum of the Air Force)

An armed observation aircraft, 203 O-52s were ordered with serials 40-2688/2890. The first flight took place in February 1941 and they served as trainers whilst a number were supplied to the USSR.

O-53 Douglas Havoc

Specifications: span: 61'4", 18.69 m length: 48', 14.63 m engines: 2 Wright R-2600-7 max. speed: 390 mph, 628 km/h

Based on the A-20B, 1489 O-53 s were ordered with serials 41-3670/5158 but were eventually cancelled.

Refer also to A-20, F-70, R-3, BD

O-54 Stinson 10 Voyager

Specifications: span: 34', 10.36 m length: 22'2", 6.76 m engines: 1 Continental O-170-1 max. speed: 100 mph, 161 km/h

(Source: Ron Dupas, via 1000aircraftphotos.com photo #2869)

Six YO-54 s were procured for evaluation. They had serials 41-143/148.

Refer also to L-5, L-9, O-62, U-19, OY

O-55 Ercoupe 415C

Specifications: span: 30', 9.14 m length: 20'2", 6.15 m engines: 1 Continental YO-170-3 max. speed: 112 mph, 180 km/h

(Source: NACA)

A single YO-55 with serial 41-18875, was procured for evaluation. It was previously registered as NC28655 althugh some reference sources suggest it was NC15692. There is photographic evidence that this aircraft was used for tests with JATO rockets with the first flight with such rockets taking place on 12 July 1941 whilst still carrying the civilian registration. Some reference sources have suggested that these tests were performed with Ercoupe c/n 2673 (N2049H) as well as with one or both the PQ-13As. There remain a number of Ercoupe 415Cs flying that are, incorrectly, being ‘labelled’ as YO-55.

Refer also to PQ-13

O-56 Lockheed 437

Specifications: span: 65'6", 19.96 m length: 51'5", 15.67 m engines: 2 Wright R-2600-13 max. speed: 298 mph, 479 km/h

The O-56 was a proposed armed observation version in the Lockheed Lexington/Ventura/Lodestar family. 550 were ordered with serials 41-37470/38019 but were eventually cancelled although the first 18 aircraft (41-37470/37487) were completed as B-37.

Refer also to B-34, B-37, C-56, C-57, C-59, C-60, C-66, C-111, PBO, PV, R5O

O-57 Taylorcraft Grasshopper

Specifications: span: 35'5", 10.80 m length: 22'9", 6.93 m engines: 1 Continental O-170-3 max. speed: 93 mph, 150 km/h

(Source: USAF)

In 1942 four YO-57 s were ordered for evaluation with serials 42-452/455. They were fitted with a YO-170-3 engine and were redesignated as O-57 on completion of testing. In addition the O-57 designation was assigned to the production version and 20 aircraft with serials 42-7773/7792 were ordered before, in April 1942 (or possibly earlier), the designation was changed into L-2, under which designation production continued. The O-57A version incorporated several changes and 335 were ordered with serials 42-15073/15158 and 42-35825/36074 before, in April 1942 (or possibly earlier) the designation was changed into L-2A, under which designation production continued.

Refer also to C-95, L-2, TG-6, LNT

O-58 Aeronca 65TC Grasshopper

Specifications: span: 35'5", 10.80 m length: 22'4", 6.81 m engines: 1 Continental O-170-3 max. speed: 87 mph, 140 km/h

(Source: Gordon Hubbard, via 1000aircraftphotos.com photo #3846)

In 1942 four YO-58 s were ordered for evaluation with serials 42-456/459. They were fitted with a YO-170-3 engine and were redesignated as O-58 on completion of testing. The O-58A version incorporated several changes and 20 were ordered with serials 42-7793/7812. In April 1942 (or possibly earlier) the designation was changed into L-3A. The O-58B version had a length of 21'10", 6.65 m and 335 were built with serials 42-14713/14797 and 42-36075/36324 before, in April 1942 (or possibly earlier), the designation was changed into L-3B under which designation production continued.

Refer also to L-3, TG-5, LNR

O-59 Piper J3C-65 Grasshopper

Specifications: span: 35'3", 10.74 m length: 22'4", 6.81 m engines: 1 Continental O-170-3 max. speed: 87 mph, 140 km/h

(Source: Piper)

More commonly known as Cub, four YO-59 aircraft were procured with serials 42-460/463. After evaluation the aircraft were redesignated as O-59 , a designation also applied to the first production version of which 140 were built with serials 42-7813/7952 before the designation changed into L-4 in April 1942 (or possibly earlier). The O-59A version had a length of 22'5", 6.83 m and 671 were ordered with serials 42-15159/15329 and 42-36325/36824 before, in April 1942 (or possibly earlier), the designation was changed into L-4A.

Refer also to C-83, L-4, L-14, TG-8, AE, HE, NE, LNP

O-60 Kellett KD-1

Specifications: rdm: 42', 12.80 m length: 21'5", 6.53 m engines: 1 Jacobs R-775-1 max. speed: 127 mph, 204 km/h

(Source: nasm.si.edu/collections/imagery.cfm)

Seven XO-60 autogyros were ordered with serials 42-13604/13610. In 1943 the first six aircraft were re-engined with a Jacobs R-915-3 and were redesignated as YO-60 .

Refer also to G-1, H-2, H-3

O-61 AGA Aviation

Specifications: rdm.: 48', 14.63 m length: 28'6", 8.69 m engines: 1 Jacobs R-755-1 max. speed: 103 mph, 166 km/h

(Source: ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov)

Originally designed by Pitcairn, which company was taken over by AGA Aviation in December 1941, six XO-61 autogyros were ordered but were subsequently cancelled. The serials were 42-13611/13616. Five were to have been converted with a Jacobs R-915-3 engine and redesignated as YO-61 . There is photographic evidence of at least one having been completed and it is believed that the second aircraft was also completed although cancellation took place before that aircraft was flown.

O-62 Stinson 76 Sentinel

Specifications: span: 34', 10.36 m length: 24'1", 7.34 m engines: 1 Lycoming O-435-1 max. speed: 115 mph, 185 km/h

(Source: USAAF?)

The O-62 , although a Stinson design, was built by Vultee. The prototype, registered NX27772, had made its first flight on 28 June 1941 and 275 aircraft were ordered as O-62 and with serials 42-14798/15072. In April 1942 (or possibly earlier) they were redesignated before the first aircraft was completed as L-5 under which designation production continued.

Refer also to L-5, L-9, O-54, U-19, OY

O-63 Interstate S.1B Grasshopper

Specifications: span: 35'6", 10.82 m length: 23'5", 7.14 m engines: 1 Franklin XO-200-5 max. speed: 114 mph, 183 km/h

(Source: National Archives)

One XO-63 was procured with serial 42-15895. In April 1942 (or possibly earlier) it was redesignated as XL-6. Production of the O-63 , with serials 43-2559/2808, was completed as L-6.

Refer also to L-6, L-8