UNITED STATES MILITARY AIRCRAFT by Jos Heyman Tri-service U=Utility The U designation was commenced in 1952 as part of the USAF designation system and was continued in the Tri-service system. Last updated: 1 July 2016
U-1 De Havilland Canada DHC-3 Otter span: 58', 17.68 m length: 41'10", 12.75 m engines: 1 Pratt & Whitney R-340-S3H1-G max. speed: 150 mph, 256 km/h (Source: Sciacchitano) The Canadian built Otter was a 14-seater light transport which flew for the first time on 12 December 1951. In total 460 were built. The US Army ordered six for evaluation with serials 55-2937/2978. They were initially designated as YC-137 but were delivered as YU-1. Following this, the US Army ordered 184 U-1As with serials 55-3244/3327, 57-6107/6136, 58-1681/1720, 58-7019 and 59-2203/2231. A number of these were converted as TU-1A trainers whilst three, including 55-3271 and 58-1714 were converted as RU-1A spotter aircraft. On 18 September 1962 those UC-1s remaining in service with the US Navy were redesignated as U-1B. They had a R-1340-AN-3 engine. Three U-1Bs were used as NU-1B for miscellaneous tests. The serials were 142425 and 144670 and 144672. Refer also to UC, AU-1
U-2 Lockheed span: 80', 24.38 m length: 49'7", 15.11 m engines: 1 Pratt & Whitney J57-P-37A max. speed: 495 mph, 796 km/h (Source: USAF, via 10af.afrc.af.mil/photos) The U-2 was a single seat high altitude strategic reconnaissance aircraft conceived in 1954 at the request of the CIA. Originally known as Angel, the U-2 designation was not applied until November 1955, ie after the first flight. The U-2A was the first version and 55 were built. The first U-2A flight took place on 1 August 1955. Some aircraft were later fitted with a J57-P-31 engine. The primary aircraft identification was the Article number (like the construction number) which ranged from 341 to 395. The aircraft were frequently swapped between the USAF and the CIA. The USAF assigned serials 56-6675/6722 and 56-6951/6955, with the serial 56-6690 used for two separate aircraft. Article 341 never received a serial, but has been shown with the number 001 on its tail. Following the shooting down of Gary Powers over Sverdlovsk on 1 May 1960 (in 56-5593), aircraft 56-6711 was displayed on 6 May 1960 with NASA markings and the false serial 55-741. The CIA aircraft received a range of NACA serials in the 160/199, 300/310 and 400 series, with numbers changing frequently. NACA serials 164, 320, 331, 357, 405, 432, 449 and 464 are known but no comprehensive list is available. In addition civil registrations N315X (for the Office of Naval Research), N800X to N809X (for the CIA) were used. It is understood CIA aircraft also flew without any markings at all. The WU-2A was a high altitude weather reconnaissance conversion of several U-2As including 56-6681, 56-6696, 56-6715, 56-6717 and 56-6722. The U-2B designation was used for a 1959 proposal for 84 early warning aircraft with similar dimensions but with a tricycle undercarriage. The version was not built and the U-2B designation was unofficially used for the U-2D two seat version. Serials included 56-6679, 56-6682/6685, 56-6690, 56-6701, 56-6714 and 56-6721. The U-2C was a version fitted with a J75-P-13 engine. U-2As 56-6675, 56-6675, 56-6680, 56-6681, 56-6682, 56-6684, 56-6685, 56-6687, 56-6691, 56-6692, 56-6693, 56-6696, 56-6700, 56-6701, 56-6702, 56-6703, 56-6705, 56-6706, 56-6707, 56-6710, 56-6712, 56-6714, 56-6716, 56-6719 and 56-6721 were converted, with the first flight taking place on 13 May 1959. Aircraft 56-6722 was also flown as JU-2C. U-2CT was the designation of a conversion from U-2Cs and WU-2Ds with a modified rear cockpit. Known serials include 56-6681, 56-6682, 56-6692, 56-6693 and 56-6953. These aircraft were also known as TU-2C. The U-2D designation referred to a two seat version of the U-2A. Sometimes referred to as U-2B, the second cockpit aft of the pilot cockpit could accommodate an observer. Aircraft with serials 56-6950/6955 were built outright as U-2D whilst 56-6682, 56-6701, 56-6714 and 56-6721 were converted to this standard in 1959. A single U-2D (56-6721) was used for temporary testing as JU-2D. The WU-2D was a high altitude weather reconnaissance conversion and serials were 56-6721, 56-6953 and 56-6954. The U-2E and U-2F are believed to have been versions with in-flight refueling facilities. Three were known as U-2E, whilst serials 56-6675, 56-6680, 56-6681, 56-6687, 56-6703, 56-6705 and 56-6707 were associated with the U-2F. The designation U-2EPX was allocated to two aircraft allocated to the US Navy for the Electronic Patrol Exponential ocean surveillance programme, which took place in 1973. Serial 68-10339 has been associated with this programme. The U-2G was a version with arrester gear of which four, including 56-6681 and 56-6682, were converted from U-2A whilst the U-2H designation has been allocated to a version with arrester gear and in-flight refueling facilities. No details are available on the reported U-2J version.
Initially designated U-2N, the U-2R was a significantly modified version with a span of 103', 31.39 m, length of 63', 19.20 m and 1 Pratt & Whitney J75-P-13B. The first flight took place on 28 August 1967 and 17 were built with serials 68-10329/10353 although it is understood that some serials were for deception purposes. The CIA flew two with registrations N803X and N810X. The designation TU-2R was used for a training version. In November 1969 the US Navy, in collaboration with the CIA, used a U-2R for carrier landing tests. The aircraft was fitted with an arresting hook whilst the outer parts of each wing folded back to facilitate handling aboard ship. The particular aircraft was registered as N812X. The TR-1A was a development of the U-2R which first flew on 1 August 1981. The serials were 79-472 and 80-1063/1099 and more may have been built. Serials 80-1100/1112 are known to have been cancelled. In 1992 those TR-1As remaining in service were redesignated as U-2R. A training version was known as the TR-1B and two are known with serials 80-1064/1065. The first one flew on 23 February 1983. The ER-2 was a special NASA version of the TR-1A and flew for the first time on 11 May 1981. Serials 80-1063 and 80-1069 have been associated with this version as well as NASA registrations N706NA and N708NA. In addition aircraft 80-1097 was converted as ER-2 (N709NA and N809NA later on) and ER-2S later. In the mid-1990s 32 U-2Rs and 3 U-2RTs were converted with General Electric F-118-GE-101 engines and were redesignated as U-2S. Serials included 68-10336, 68-10337, 80-1066, 80-1067, 80-1068, 80-1069, 80-1070, 80-1071, 80-1073, 80-1074, 80-1076, 80-1077, 80-1078, 80-1079, 80-1080, 80-1081, 80-1083, 80-1084, 80-1085, 80-1086, 80-1087, 80-1089, 80-1090, 80-1092 and 80-1095. The designation TU-2S or U-2ST was used for a training version. Two aircraft, with serials 80-1078 and 80-1091 were converted from TR-1As. Refer also to R-1 and R-2
U-3 Cessna 310 span: 36', 10.97 m length: 27'1", 8.26 m engines: 2 Continental O-470-M max. speed: 232 mph, 373 km/h (Source: RuthAS, via wikepedia) In August1958 those L-27As remaining in service were redesignated as U-3A. Two U-3As of the USAF went to the US Navy as U-3A with serials 159073/159074 whereas others were flown by the US Navy with their original serial.. The U-3B, sometimes incorrectly referred to a L-27B, was based on the model 310M with a swept tail. It had a span of 36'11", 11.25 m, a length of 8.79 m and IO-470-D engines and 35 were ordered with serials 60-6047/6081. In 1967 the USAF purchased two Cessna 310Ls for Iran with serials 67-14860/14861. Several Cessna 310 aircraft were confiscated with serials 82-23786, 83-24151, 84-24312 and 85-25350 but these did not receive a designation. In addition a number of aircraft were operated by the USAF with civilian registrations N6979L, N7020L, N9360A, N4168Q and N7571Q. These did not receive a designation too. Some of the latter aircraft may be same as those undesignated aircraft for which the serials are known although it has not been possible to match them due to insuffcient data. Refer also to L-27
U-4 Aero Commander span: 44'1", 13.44 m length: 35'5", 10.80 m engines: 2 Lycoming GO-480-D1A max. speed: 206 mph, 331 km/h (Source: nationalmuseum.af.mil/factsheets/index.asp) In 1960 those L-26Bs and L-26Cs remaining in service with the USAF were redesignated as U-4A and U-4B. The serial 55-2714 was used for an Aero Commander 560 c/n 214 which had previously flown as N2714B. It was acquired on 7 January 1971 and was delivered to the Laos Air Force. It carried designation U-4 (no suffix letter). Refer also to L-26, U-9
U-5 Helio H500 Twin Courier span: 41', 12.50 m length: 30'3", 9.22 m engines: 2 Lycoming O-540-A2B max. speed: 187 mph, 301 km/h (Source: Heliocourier.net) Two aircraft were procured for evaluation as U-5A with serials 59-5955/5956. Another three were procured as U-5B with serials 63-8072/8074. Some reference sources claim seven aircraft were evaluated or delivered to the CIA. These were probably operated with civilian registrations. One aircraft carried a serial 90336 which was out of sequence. The designation XU-5 is also known.
U-6 De Havilland Canada DHC-2 Beaver span: 48', 14.63 m length: 30'3", 9.22 m engines: 1 Pratt & Whitney R-985-AN-1 max. speed: 180 mph, 290 km/h (Source: US Army) On 18 September 1962 those L-20As remaining in service were redesignated as U-6A, whilst a further aircraft with serial 64-15462 was purchased outright as a U-6A. This included US Navy L-20 150191 and 150192 which had been transferred from the US Army to the US Navy in 1961 as well as 151348. In addition the US Navy used two U-6As with serials 164524 and 164525. The latter was used at the US Naval Test Pilot School as a glider tug. The designation NU-6A was used by one aircraft with serial 53-2781. A number of U-6As were converted as RU-6A spotter aircraft, including 53-2786, 53-2833, 53-7948, 53-7956, 53-7957, 54-1667, 54-1724, 55-682, 56-377, 56-4432, 57-3724, 57-6151 and 58-2012, and TU-6A trainers, the latter including 51-16489. Refer also to L-20, U2C
U-7 Piper Super Cub span: 35'3", 10.74 m length: 22'6", 6.86 m engines: 1 Lycoming O-290-D2 max. speed: 130 mph, 209 km/h On 18 September 1962 those L-21Bs remaining in service were redesignated as U-7A. Refer also to L-18, L-21
U-8 Beechcraft Seminole span: 45'4", 13.82 m length: 31'7", 9.63 m engines: 2 Lycoming O-480-1 max. speed: 233 mph, 375 km/h (Source: US Army) The Seminole was a military version of the Twin Bonanza. On 18 September 1962 those aircraft remaining in service were redesignated as follows: USAF Tri-service L-23D U-8D RL-23D RU-8D L-23E U-8E L-23F U-8F The U-8A, U-8B and U-8C designations were not assigned. A number of U-8Ds were converted to RU-8D including serials 56-3700, 56-3702, 56-3711, 56-3712, 56-3713, 58-1331, 58-1340/1342, 58-1345, 59-2535 and 59-2540/2543. The U-8E version was fitted with 2 Lycoming O-480-3 engines and a single aircraft was further fitted with advanced electronic equipment and tested as NU-8E with an unofficial serial 66-15360. Although the U-8F designation was applied to ex L-23Fs, of which further examples were purchased as U-8F with serials 63-7975, 63-13636/13637 and 66-15365, it was also used for additional Queen Air 65 aircraft purchased for the ANG on the second hand market with serials 81-13658/13659, 81-23658, 82-23659, 82-23840/23841, 83-23844, 83-23847, 83-23850, 83-23857 and 83-23872. Some of these serials were duplicated. The US Navy operated a U-8F with serial 161627. The U-8F had a span of 45'11", 14.00 m, length of 33'4", 10.16 m, 2 Lycoming IGSO-480-A1A6 and a max. speed of 240 mph, 386 km/h. The RU-8F was a conversion for reconnaissance duties by the Army. The NU-8F was similar to the U-8F but had a length of 35'6", 10.82 m and 1 Pratt & Whitney PT6A-6 engines. Carrying serial 63-12902 and flown for the first time in May 1963, it served as a prototype for the U-21A and was converted from a U-8A with Twin Bonanza wings and Queen Air 80 fuselage. Some references include aircraft 66-15361 as a NU-8F but this was in fact a VC-6A. The designation VU-8F was assigned to aircraft 66-15365, a converted U-8F. The U-8G designation was used for a number of U-8Ds, RU-8Ds, U-8Es and U-8Fs converted with Lycoming GO-480-CSC6 engines. Serials included 55-3465, 56-3710, 56-4039, 56-4041, 56-4043, 56-4044, 57-6085, 57-6089, 58-1329, 58-1336, 58-1339, 58-1348, 58-1357, 58-1359, 58-1360, 58-1363, 58-1364, 58-3055, 58-3057, 58-3062, 59-2536/2538 and 59-4990. The TU-8G was a training version of the U-8G for the US Navy, development of which was cancelled and became the T-42A. There is a 1960 reference to a U-8H version for the US Army, linked to the 65-A90-1 version. Several civilian Queen Airs were confiscated without a designation. They included serials 80-23525, 82-24029, 82-24054, 83-24128, 83-24188, 84-24320, 85-24370, 85-24373/24374 and 85-25349. Some of these serials were duplicated. Refer also to C-6, L-23, T-42, T-44, U-21
U-9 Aero Commander span: 44'1", 13.44 m length: 35'5", 10.80 m engines: 2 Lycoming GO-480-C1BL max. speed: 206 mph, 331 km/h (Source: Jos Heyman) On 18 September 1962 those Aero Commanders remaining in service with the US Army were redesignated as follows USAF Tri-service YL-26 YU-9A L-26B U-9B L-26C U-9C NL-26D NU-9D RL-26D RU-9D The reason why these aircraft were redesignated as U-9 and not U-4 is not clear except for their use by the different services. The YU-9A had a span of 44'7", 13.59 m, a length of 34'5", 10.49 m and had 2 Lycoming GO-435-C2B engines. The designation U-9D was used for one or more U-9Cs converted for air sampling missions. The NU-9D designation was applied to one aircraft only with serial 57-6531 whilst the RU-9D designation was applied to 57-6183/6184. Both aircraft were later converted as NRU-9D. The first of these aircraft was later transferred to the US Navy and used with USAF serial. Several civilian Aero Commanders were confiscated without a designation and serials 63-7948, 83-24126 and 83-24127. Refer also to L-26, U-4
U-10 Helio H395 Super Courier span: 39', 11.89 m length: 31',9.45 m engines: 1 Lycoming GO-435-C2B2-G max. speed: 176 mph, 281 km/h (Source: USAF) The Super Courier was a small STOL aircraft. On 18 September 1962 those L-28As remaining in service were redesignated as U-10A. In addition another 26 were built outright as U-10A with serials 62-3603/3608, 62-5119, 62-5907/5920, 63-13099/13101 and 63-13184/13185. The U-10B version was fitted with a Lycoming GO-480-G1D6 engine and 57 were built with serials 63-8091/8110, 63-13090/13098, 63-13102/13113, 63-13166/13183 and 66-14370/14375. The U-10C designation was assigned to a U-10A version with a Lycoming IGSO-540-B1A engine. The version was not proceeded with. The U-10D version was similar to the U-10B and 36 were built with serials 63-13096/13098, 63-13102/13106 (ordered as or converted from U-10B) and 66-14332/14369. Refer also to L-24, L-28
U-11 Piper Aztec span: 37', 11.28 m length: 27'2", 8.41 m engines: 2 Lycoming O-540 max. speed: 215 mph, 346 km/h (Source: William T. Larkins) On 18 September 1962 those UO-1s remaining in service with the US Navy were redesignated as U-11A. The USAF operated three Aztecs without designation or serials and with civilian registrations N120D, N2219P and N6221Y. Refer also to UO
U-12 to U-15 The U-12 to U-15 designations have not been assigned. The probable reason for this is possibly that, with the next convenient designation being U-16, there were no aircraft to carry this designation.
U-16 Grumman G-64 Albatross span: 80', 24.38 m length: 60'8", 18.49 m engines: 2 Wright R-1820-76A max. speed: 270 mph, 434 km/h (Source: USCG) The Albatross was a twin engined amphibian rescue aircraft used by the USAF, US Navy and USCG. On 18 September 1962 those aircraft remaining in service were redesignated as follows: USAF/US Navy Tri-service SA-16A HU-16A SA-16B HU-16B UF-1 HU-16C UF-1L LU-16C UF-1T TU-16C UF-2 HU-16D UF-2G HU-16E The HU-16C was similar to the HU-16A whilst the HU-16B and HU-16D versions had a span of 96'8", 29.46 m and length of 62'10", 19.15 m. The designation SHU-16B was applied to two aircraft converted as prototypes of an anti-submarine version considered for export. They carried serials 51-048 and 51-050 and the first flight of these aircraft was on 11 May 1961, at which time they were known as SA-16B/ASW. Following successful tests a total 37 aircraft were converted with serials 49-097, 49-099, 49-100, 51-014, 51-024, 51-038, 51-040/041, 51-044, 51-060, 51-068/070, 51-474, 51-5281, 51-5283, 51-5288, 51-5289, 51-5300, 51-7147/7148, 51-7165, 51-7167, 51-7170, 51-7172, 51-7174, 51-7177, 51-7183, 51-7190/7191, 51-7196, 51-7201/7204 and 51-7207. They were supplied to Norway, Spain, Chile, Peru and Indonesia. A EU-16E version for the USCG was proposed in November 1973 but cancelled again in April 1974. The HU-16F designation was applied to a 1967 projected version of the HU-16B to be fitted with 2 General Electric T64 engines. Other proposals with turbo prop engines had also been made and whilst a number of Albatrosses were eventually fitted with turbo props, none of these were military aircraft. Refer also to A-16, JR2F, PF, UF
U-17 Cessna 185 Skywagon span: 35'10", 10.92 m length: 25'9", 7.85 m engines: 1 Continental IO-470-F max. speed: 178 mph, 286 km/h (Source: South Vietnam Air Force) The Skywagon was a light utility transport which flew for the first time in July 1960. The USAF ordered large quantities but most of these were supplied to overseas air forces. The U-17A was similar to the model 185C and 262 were built with serials 63-9692/9697, 63-9794/9809, 63-13005, 63-13015/13039, 63-13135/13138, 63-13279/13285, 63-13594/13600, 64-14867/14869, 64-15433/15459, 64-17796/17797, 64-17905/17948, 65-10827/10854, 65-12678, 65-12734/12737, 65-12908/12913, 66-8033/8038, 66-8531/8549, 66-13263/13277, 66-13297/13314, 66-13527/13532, 66-13563/13570, 66-14421/14427, 67-14497/14502 and 67-14602/14603. A batch with serials 64-15460/15461, 67-14487/14496 was cancelled. The U-17B version incorporated minor equipment chances and 205 were procured with serials 67-14542/14543, 67-22518/22541, 68-8936/8943, 68-10538, 69-7280/7284, 69-7304/7312, 69-7539/7545, 69-7670/7674, 70-1443/1534, 70-1623, 70-2036, 71-1039/1050, 71-1422/1457, 72-1357/1358 and 73-1616/1625. The designation U-17C was applied to seven models 180H fitted with a Continental O-470-R. the serials were 65-12770/12771, 67-14580/14581, 70-1624 and 70-2034/2035. The U-17D version was cancelled. The assigned serials were 70-1963/2020. In 1986 the US Army acquired a confiscated Cessna 185 with serial 86-142.
U-18 Ryan Navion span: 33'4", 10.16 m length: 27'3", 8.31 m engines: 1 Continental O-470-7 max. speed: 150 mph, 241 km/h (Source: Geoffrey P Jones) On 18 September 1962 those Ryan Navions remaining in service were redesignated as follows: USAF Tri-service L-17A U-18A L-17B U-18B L-17C U-18C The U-18B version had a O-470-9 engine. Refer also to L-17
U-19 Stinson Sentinel span: 34', 10.36 m length: 24'1", 7.34 m engines: 1 Lycoming O-435-1 max. speed: 115 mph, 185 km/h On 18 September 1962 five L-5s and one L-5G (57-6278) were redesignated as respectively U-19A and U-19B. The latter version had O-435-11 engines. Refer also to L-5, L-9, O-54, O-62, OY
U-20 Cessna 195 span: 36'2", 11.02 m length: 27'2", 8.28 m engines: 1 Jacobs R-755-11 max. speed: 180 mph, 290 km/h On 18 September 1962 those LC-126Cs and LC-126Bs remaining in service were designated as U-20A and U-20B respectively. Refer also to C-126
U-21 Beechcraft 65-A90 span: 45'11", 14.00 m length: 35'6", 10.82 m engines: 2 Pratt & Whitney PT6A-20 max. speed: 250 mph, 402 km/h (Source: US Army) The U-21 was a military version of the King Air twin engines transport. Following the development of the prototype as NU-8F, 141 examples of the model 65-A90-1C with a Queen Air 65-80 fuselage and the King Air 65-90 wings were ordered as U-21A for utility missions in the combat zone. The serials were 66-18000/18040, 67-18041/18076, 67-18078/18084, 67-18086, 67-18088, 67-18090/18092, 67-18094/18103 and 67-18112/18118, whilst a batch with serials 70-15891/15907 was completed as U-21G. Various aircraft were converted to RU-21A, RU-21B, RU-21C and RU-21D before completion. The EU-21A was an electronic warfare conversion of the U-21A and was applied to aircraft with serials 66-18000, 66-18003, 66-18027, 67-18055, 67-18058, 67-18073 and 67-18074. The conversion took place in 1967. Several U-21As were used as JU-21As for temporary testing. Serials included 66-18008, 66-18009, 66-18036, 67-18063, 67-18065 and 67-18069. The RU-21A designation was applied to seven U-21As converted for reconnaissance/interception duties. Their serials included 67-18059 and 67-18112/18115. They had a span of 50'11" 15.52 m. The U-21B was fitted with 2 Pratt & Whitney PT6A-29 engines and three were procured with serials 67-18077, 67-18087 and 67-18093. The three aircraft were later converted to RU-21B standards with communications jamming systems. Similar to the U-21B two RU-21Cs were built with serials 67-18085 and 67-18089. 18 of the U-21As were completed as RU-21D whilst a further number were purchased outright. The serials were 67-18104/18111 and 67-18119/18128. Aircraft 67-18105, 67-18111 and 67-18125 were further modified as JRU-21D. A number of RU-21Ds (67-18104, 67-18108, 67-18120, 67-18122, 67-18123, 67-18124, 67-18126, 67-18127 and 67-18129) were later converted as U-21D. The next version was fitted with Pratt & Whitney T74-CP-700 engines and designated as RU-21E. The aircraft are popularly known as Guardrail. The serials of the RU-21Es were 70-15875/15890. Three RU-21Ds were also converted to this standard. The U-21F designation was used for 5 King Air A100s used by the US Army for communications duties with serials 70-15908/15912. They had a length of 39'11", 12.17 m and 2 PT6A-28 engines. The U-21G designation was applied to U-21As completed with the new designation. These included serials 70-15891/15907. Aircraft with serials 70-15901/15906 were used as JU-21G. Three U-21Gs with serials 70-15893, 70-15898 and 70-15899 were converted as RU-21G. The RU-21H designation applied to a number of RU-21Es and RU-21Gs converted as Guardrail II, IV and V, including serials 67-18105, 67-18111, 67-18119, 70-15875/15889, 70-15891, 70-15893/15895, 70-15898/15899 and 70-15902/15904. Other Guardrail aircraft used C-12 airframes. Some RU-21Hs were later converted to U-21H including 67-18105, 67-18111, 67-18119, 70-15875, 70-15877/15878, 70-15881/15882 and 70-15888. Aircraft with serial 70-15877 and 70-15888 were used as JU-21H. The RU-21J was based on the Super King Air and had a span of 54'6", 16.61 m, length of 43'9", 13.34 m and was fitted with PT6A-41 engines. 3 were ordered with serials 71-21058/21060 and were later converted to C-12L. Several were later converted as U-21J. A Beech B100 was confiscated with serial 90-060. Refer also to C-6, C-12, U-8, T-42, T-44
U-22 Beechcraft Bonanza span: 39 5", 12.02 m length: 26'4", 8.03 m engines: 1 Continental IO-520-B max. speed: 207 mph, 333 km/h (Source: nationalmuseum.af.mil/factsheets/index.asp) The Beechcraft Bonanza, which had first flown as a civilian aircraft on 22 December 1945, was used for several military applications. The YQU-22A was applied to six aircraft ordered as electronic reconnaissance drones with provisions for a control pilot. The serials were 68-10531/10536 and the company model number was PD1079. The first aircraft arrived in Vietnam in March 1969. The YAU-22A designation was applied to a low cost close support aircraft with underwing pylons for machine gun pods. The prototype, with company model PD249 and registration N5847K, was acquired by the USAF for the Pave Coin programme with serial 70-7859, the serial being based on the construction number. The QU-22B was the production drone model of which 27 were built and used in Vietnam in conjunction with EC-121Rs. The serials were 69-7693/7705 and 70-1535/1548. Serials 71-37586/37596 have also been quoted.
U-23 Fairchild Peacemaker span: 49'8", 15.14 m length: 36'10", 11.23 m engines: 1 Garrett Air TPE331-1101F max. speed: 174 mph, 280 km/h (Source: USAF?) A licence built version of the Pilatus PC-6 Porter was tested as AU-23A in the Credible Chase programme, a 1971/1972 programme to assist the South Vietnamese Air Force. The aircraft fitted with four underwing pylons and a XM-197 cannon. 36 were built of which 28 were supplied to the Thai Air Force and 5 to the Thai Police. None were supplied to South Vietnam. Serials were 72-1304/1318, 73-1699 and 74-2073/2092. From December 1963 to May 1965 the USAF evaluated a Pilatus Porter with civilan registration N184L in Florida. This aircraft went later to Air America. Refer also to V-12, V-20
U-24 Helio H550A Stallion span: 41'9", 12.73 m length: 39'7", 12.07 m engines: 1 Pratt & Whitney PT6A-27 max. speed: 215 mph, 346 km/h (Source: Stephen Ruby, via aeroweb.org) The AU-24A was an aircraft in the Credible Chase programme of 1971/1972 fto provide the South Vietnamese Air Force with additional firepower. The aircraft was armed with a XM-197 cannon. 15 were ordered with serials 72-1319/1933 but none were delivered to South Vietnam. Eventually 14 (all except 72-1324) were supplied to Cambodia in 1972. Most of these were captured by the Khmer Rouge in 1975 whilst three escaped to Thailand.
U-25 Dassault Guardian span: 53'6", 16.61 m length: 56'3", 17.15 m engines: 2 Garrett Air ATF-3 max. speed: 536 mph, 862 km/h (Source: USCG) Originally the designation U-25A was assigned to the Beechcraft Huron but these aircraft were eventually ordered as C-12A. The HU-25A was a special version of the Dassault Falcon for use by the USCG. The aircraft were ordered on 7 January 1977 and the first flight was on 28 November 1977. The serials were 2101/2141. The HU-25B was a version equipped with side-looking radar used for oil spill surveillance and eight HU-25As were converted. They had serials 2101, 2103, 2111, 2118, 2122, 2125, 2126 and 2132. The HU-25C designation was applied to nine HU-25As converted to combat drug smuggling. They were aircraft with serials 2104, 2112, 2129, 2131, 2133, 2135, 2139, 2140 and 2141. Further conversions with upgraded sensors of some HU-25As and all HU-26C as HU-25D, commenced in 2003. The conversions included serials 2102, 2104, 2105, 2107, 2112, 2113, 2114, 2116, 2117, 2127, 2128, 2129, 2131, 2133, 2135, 2139, 2140 and 2141.
U-26 Cessna 206 Turbo Super Skywagon span: 35'10", 10.92 m length: 32'3", 9.83 m engines: 1 Continental TSIO-520-C max. speed: 196 mph, 315 km/h Light utility transport. One was procured for the Air Force Academy as U-26A with serial 82-667. Four models 206 were supplied to Costa Rica.
U-27 Cessna 208A Caravan span: 52'1", 15.88 m length: 37'7", 11.46 m engines: 1 Pratt & Whitney PT6A-114 max. speed: 214 mph, 344 km/h (Source: B.C.F. Klein, via 1000aircraftphotos.com photo #7094) A light utility transport for 13 passengers which first flew on 9 December 1982. Three examples were built as U-27A for potential supply to foreign air services. They were evaluated by the US Army and were also considered as a gunship for the USAF. The aircraft were not ordered and they were registered N9514F, N9698F and N208LP, whilst they also carried their construction number as a pseudo serial: 2080079, 2080129 and 208689 respectively. It is believed Liberia, Brazil and Nigeria ordered aircraft whilst one was leased by the US Army. In 2007 the USAF acquired three aircraft with civilian registrations N1321A, N13210 and N13217 for delivery to the Iraq AF. A further five aircraft were procured in 2008. Two Cessna Caravans were operated at one stage with serials 96-6047 and 96-6048. The US Army operated two Cessna 208 Caravans in 2012. One of these was serialled as 12-1276. Refer also to C-16
U-28 Pilatus PC-12 span: 53 3, 16.23 m length: 47 3, 14.40 m engines: 1 Pratt & Whitney PT6A-67B max. speed: 312 mph, 500 km/h (Source: americanspecialops.com) First flown on 31 May 1991, the USAF acquired a number of aircraft from 2005 designated as U-28A. They were used for special operations and had serials 01-0415, 04-0602, 04-0688, 05-0409, 05-0419, 05-0424, 05-0446, 05-0447, 05-0482, 05-0556, 05-0573, 05-0597, 05-0646, 06-0692, 06-0740, 07-0488, 07-0691, 07-0779, 07-0793, 07-0808, 07-0821, 07-0838, 08-0519, 08-0581, 08-0724, 08-0822, 08-0835 and 08-0850. These serials were based on the construction number and the FY are sometimes shown differently. There was also a U-28B version with serials 07-0700, 07-0711, 07-0712, 07-0736, 07-0777, 07-0829, 07-0840, 08-0718, 08-0790, 08-0809, 08-0822 and 08-0835. Again the serials were based on the construction numbers.