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Dιsignation des hιlicoptθres Amιricains by Jean BIZOT |
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Dιsignation des hιlicoptθres Amιricains by Jean BIZOT |
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The current designation system for U.S. military aircraft was introduced by the Department of Defense on 18 September 1962. It is based on the system used by the U.S. Air Force between 1948 and 1962, and replaced the older systems used by the U.S Navy (and Marine Corps) and the U.S. Army. Existing aircraft with designations not compliant with the new system (all Navy and Marine Corps, many Army, and a few Air Force aircraft) were given new designations. According to the rules, all aircraft operated by the U.S. military services are to receive an official designation, but in practice, all services operate a few off-the-shelf aircraft under the manufacturers' designations. The U.S. Coast Guard also allocates military designations to most of its aircraft, and NASA uses the X- for-eXperimental designation series extensively for its own research aircraft.
Military aerospace vehicle designation is also known as an "MDS Designation" (Mission-Design-Series), naming the three most important components of the designation. An MDS looks as follows (all examples are real-world designations):
(1) Status Prefix: Any aircraft, which is not in normal operational service, can receive a prefix letter in its designation to reflect its current status. Because both modified mission (2) and status prefix letters can appear to the left of the basic mission symbol, both groups of letters are distinct to avoid ambiguities. The following status prefixes are defined:
J - Special Test, Temporary [1962-today] (J prefix is used if the helicopter is planned to be converted back to original configuration after tests have ended)
X - Experimental [1962-today] Y - Prototype [1962-today]
(2) Modified Mission: An optional modified mission letter can be used, when an aircraft is used for a different purpose than originally designed. The regulations say that no more than one modified mission letter can be used, but this rule has been violated a few times. The modified mission symbols are in general the same as the basic mission symbols, but add a few more letters. The following modified mission symbols are defined: A - Ground Attack [1962-today] C - Transport [1962-today] E - Special Electronic Mission [1962-today] H - Search and Rescue, Medevac [1962-today] M - Multi-mission [1974-today] mostly used for Special Forces rotorcraft O - Observation [1974-today] R - Reconnaissance [1962-today] S - Antisubmarine Warfare [1962-today] T - Trainer [1962-today] U - Utility [1962-today] V - Staff Transport [1962-today] (V was originally used for all staff transport aircraft, but now is limited to helicopters used by the President of United States)
(3) Basic Mission: designates the basic mission of the aircraft, for which it has been designed. Designations, which include a vehicle type symbol, must also include at least one basic or modified mission symbol to designate the mission of the aircraft. The following basic mission symbols are defined: A - Ground Attack [1962-today] C - Transport [1962-today] E - Special Electronic Mission [1962-today] O - Observation [1962-today] R - Reconnaissance [1962-today] (R designator is used by US Navy (i.e. RH-53A - helicopter for mine countermeasure), basically because there is no special prefix for anti-mining mission. The R-for-Recce letter being apparently the best-fit for mine hunting mission) S - Antisubmarine Warfare [1962-today] T - Trainer [1962-today] U - Utility [1962-today] X - Special Research [1962-today]
(4) Vehicle Type: The following symbols designate the type of aircraft: H - Helicopter [1962-today] Q - UAV/UCAV [1997-today] (Q designates reusable Unmanned Aircraft Vehicle - UAV and armed UAV version named Unmanned Combat Aerial Vehicle - UCAV) V - VTOL/STOL [1962-today] (V definition applies to all vertical take-off capable aircraft, not only rotary-wing machines)
(5) Dash Separator: - Always present into any designation, to separate information
(6) Design Number: Helicopters are designated in a single numerical sequence. According to the instructions, the numbers in each series are to be assigned in strict numerical sequence without reference to manufacturers model numbers and/or existing numbers in other MDS series. For more information, see below on Non-Standard DOD Aircraft Designations.
(7) Series Letter: Variants of a basic aircraft type are designated by a suffix letter. The series letter is actually a mandatory component of a conforming MDS, and therefore "plain" designations like "UH-1" always designate the general type of aircraft and never a specific model. The first model always receives suffix "A" and subsequent series letters are to be assigned in strict sequence (omitting "I" and "O" to avoid confusion with numerals "1" and "0").
(8) Popular Name: Many U.S. military aircraft have an official "popular name" assigned. This official name has to run through an approval process in which proposed names are checked for conflicts with existing names (both military and commercial) and their "political correctness". Official names tend to be disregarded in the USAF, when in the US Army tradition of naming aircraft by native Indian tribes name is maintained and proposed official name follows approval process. There are exceptions, Black Hawk for example). US Navy uses generally the name proposed by the manufacturer.
Block number and manufacturer code letter: Block numbers are not used with helicopters. The original designation system as defined in 1962 also mandated the use of a two-letter code suffix to identify the manufacturing plant of an aircraft. However, manufacturers' codes have been partially used with rotary-wing aircraft and are no longer mentioned in the current regulation. For what it's worth, the list of code letters for helicopter manufacturers as defined in 1962: BF - Bell Helicopter Corp., Forth Worth, Texas BV - Boeing Co. (Vertol Division), Morton, Pennsylvania DM - Doman Helicopter, Inc., Danbury, Connecticut GY - Gyrodyne Co. of America, Inc., St. James, New York HI - Hiller Helicopter Corp., Palo Alto, California HU - Hughes Tool Co., San Diego, California KA - Kaman Helicopter Corp., Windsor Locks, Connecticut LO - Lockheed Aircraft Corp., Burbank, California PI - Piasecki Aircraft Corp., Philadelphia, Pennsylvania RE - Republic Aviation Corp., Farmingdale, New York RY - Ryan Aeronautical Co., San Diego, California SI - Sikorsky Aircraft Division, Stratford, Connecticut SW - Schweizer Aircraft Corp., Elmira, New York
Non standard designations: Sometimes the same basic designation is used for rather different aircraft. Typical examples include the H-1 series, shared by the UH-1 and AH-1 helicopters
Missing Helicopter designations: The current designation system follows previous alphanumerical designators established by USAAF, USAAC, and USN. However, there are few gaps left in the designation listings. This list of designations presents explanation for each unused designator for helicopter, which use began during World War II with Sikorsky VS-316 model.
H-36: The H-36 designation is generally associated with Bell, without any details though. However, a USAF letter of 1 June 1959 allocates H-36 to a secret project called LONG EARS. The same letter also allocates the designations H-38 and H-44 (q.v.) to other secret projects. The allocation of three non-sequential designators in a single letter is unusual, but can be explained.
H-42: XH-42 was allocated to a Hughes Model 269 for the U.S. Army, which eventually became the YHO-2HU. It was later developed as the TH-55A Osage.
H-49: XH-49A was briefly allocated in 1962 to a Boeing-Vertol Model 107 helicopter for the USAF. The designation was changed to XCH-46B before September 1962.
H-69: When the VH-71A designation was assigned to the Lockheed Martin US-101 (winner of the VXX (Presidential Helicopter) competition), the design numbers 69 and 70 in the H-series were skipped. As has been confirmed by the VXX Program Office, the number "69" was regarded as embarrassing, because that number is also used to name for a certain practice. According to USAF/XPPE, H-69 will not be assigned in the future to any helicopter.
H-70: The designation H-70 has not been used for the VXX (see above), because the VXX Program Office argued that the helicopter number "70" is already widely associated with the Sikorsky S-70 family (designated H-60 in the U.S. military). The request for VH-71A was accepted by USAF/XPPE, apparently without much discussion, because "VH-71" had already been used by the VXX Program Office before the MDS had been officially assigned. Accordingly, the H-70 slot remained open for assignment (other than H-69), and could be allocated to the next helicopter design for the U.S. military.
Since, the H-70 has been attributed to the Bell 407X ARH contender and winner of the competition naming it YRH-70A for Y = prototype, R = Reconnaissance, H = Helicopter, 70 = sequential number, A = first version
..Thats all folks. Capt. Jean Bizot |
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