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{{Infobox Aircraft
  |name= C-123 Provider
  |image= Image:AC Fairchild C123 colour.jpg
  |caption= A United States Coast Guard HC-123B Provider.
  |type= Military transport aircraft
  |manufacturer = Chase Aircraft <br/>Fairchild Aircraft
  |designer=
  |first flight= 14 October 1949
  |introduced=
  |retired=
  |status=
  |primary user= United States Air Force
  |more users= United States Coast Guard 
  |produced=
  |number built=
  |unit cost=
  |developed from = 
  |variants with their own articles = Stroukoff YC-134
}}

The '''C-123 Provider''' was an American military transport aircraft designed by Chase Aircraft and subsequently built by Fairchild Aircraft for the United States Air Force. In addition to its USAF service, which included later service with the Air Force Reserve and Air National Guard, it also went on to serve most notably with the United States Coast Guard and various air forces in South East Asia.

==Design and development==
thumb|right|An early USAF C-123
The '''C-123 Provider''' was designed originally as an assault glider aircraft for the Boeing B-47 Stratojet. It was initially well regarded for tactical troop transport for its ruggedness and reliability and ability to operate from short and unimproved airstrips, which meant the low slung turbojets, prone to ingesting foreign objects, were dropped in favor of the more conventional option. The XC-123A had its engines replaced with R-2800s and was redesignated '''YC-123D'''.

By Fairchild Engine and Airplane, who assumed production of the former Chase C-123B, a refined version of the XC-123.<ref> Gunston 1977, p. 164.</ref>

==Operational history==
The first recipients of C-123 aircraft would be USAF transport units, soon followed by the US Air Force Demonstration Team, the "Thunderbirds," would use C-123s for a time. The type would also be widely exported under various US military assistance programs, directly from USAF stocks.

The aircraft was nearly ignored by the USAF for service in Vietnam, but a political rivalry with the US Army and the Army's use of the CV-2 Caribou and later pre-production order for the C-8 Buffalo, led to a decision to deploy C-123s there. To compete with the well-performing CV-2, the USAF and Fairchild furthered development on the C-123 to allow it to do similar work on short runways. This additional development increased the utility of the aircraft and its variants to allow it to perform a number of unique tasks, including the '''HC-123B''' which operated with the USCG fitted with additional radar equipment for search and rescue missions, and the '''C-123J''' which were fitted with retractable skis for operations in Greenland and Alaska on compacted snow runways.

thumb|right|C-123K of the VNAF
thumb|right|Front view of a C-123K on display at [[Dover AFB in July 2007.]]

By 1962, the '''C-123K''' variant aircraft was evaluated for operations in Southeast Asia and their stellar performance led the Air Force to upgrade 180 of the C-123B aircraft to the new C-123K standard, which featured auxiliary jet pods underneath the wings, and anti-skid brakes. In 1968, the aircraft helped resupply troops in Khe Sanh, Vietnam during a three-month siege by North Vietnam<ref name= "Gunston p. 170"> Gunston 1980, p. 170.</ref>. 

A number of C-123s were configured as VIP transports, including General Convair VC-131D.

The first C-123s to reach South Vietnam were part of the USAF's Special Aerial Spray Flight, as part of Operation '''Ranch Hand''' tasked with defoliating the jungle in order to deny rebels their traditional hiding places<ref name= "Gunston p. 171"> Gunston 1980, p. 171.</ref>. These aircraft began their operations at the end of 1961. Aircraft fitted with spraying equipment were given the U prefix as a role modifier, with the most common types being the '''UC-123B''' and the '''UC-123K'''. Aircraft configured for this use were the last to see military service, in the control of outbreaks of insect-borne disease. The C-123 was also used as "jump aircraft" for U.S. Army Airborne students located at Lawson Army Airfield, Fort Benning, Georgia in the late 1970s and early 1980s. This aircraft was used in conjunction with the C-130 Hercules and C-141 Starlifter. 

===Experimental projects===
In 1954, the '''YC-123D''', formerly the XC-123A prototype, flew in its modified state after being converted by '''Stroukoff Aircraft'''. While the most obvious change from the original XC-123A was the switch of engines, the YC-123D also had a Boundary layer control (BLC) system fitted. This system directs air from the engines at high speed over the top of the wing, making the wing act as if the aircraft is flying at a much higher airspeed. As a result, the YC-123D had a greatly reduced take-off and landing distance. Compared to the C-123B, the YC-123D could land in 755 feet instead of 1,200, and take-off with only 850 feet of runway instead of 1,950, with a 50,000 pound total weight.

In 1955 Stroukoff, under contract from the USAF, produced a single '''YC-123E''', designed to be able to take off from any surface, and also equipped with BLC. The new aircraft also featured Stroukoff's ''Pantobase'' system, combining a ski system with a sealed fuselage and wing mounted floats, while retaining its normal landing gear. The skis worked both on snow and water, and the system effectively allowed the aircraft to land on water, land, snow or ice.

''See Also YC-134''

In 1956 the USAF awarded a contract to Fairchild to design an improved version of the C-123 under the designation '''C-136''', but the contract was cancelled before the aircraft was built<ref>[http://www.designation-systems.net/usmilav/missing-mds.html "Missing" USAF designations] retrieved 2007-11-15.</ref>.

At much the same time the '''YC-123H''' was under development, the product of a Fairchild modification program started in 1956 and completed in 1957. A "Jet Augmentation Program" for existing C-123Bs had been initiated in 1955 at the behest of the USAF, and in the YC-123H contract the USAF expanded it to allow the mounting of two pod-mounted General Electric CJ-610 (later developed as the military J85) turbojets. Perhaps more impressive was the new wide-track main landing gear, noticeable since the larger gear and tires required the removal of the landing gear doors. The new gear reduced the aircraft's turning radius and improved the Maximum Take Off Weight (MTOW) of the aircraft, along with being rugged enough to stand up to unimproved runways, all important factors for the C-123's mission profile. Testing both in the United States and in South Vietnam continued until the YC-123H crashed in an accident in 1963. However, many of the design improvements were carried over to the C-123K.

In 1979, the Royal Thai government, seeking to extend the life of their C-123 fleet, placed a contract with the '''Mancro Aircraft Company''', supported by the USAF, to convert a single C-123B to Allison T56-A-7 turboprops were used and by the time the aircraft, dubbed '''C-123T''', was complete it had new "wet" wings, an Auxiliary Power Unit (APU) to assist with power movement of the control surfaces, and a heating system for the cargo compartments that also fed a new deicing system. Budgetary restrictions forced the Thai government to abandon the program in 1981, and with a lack of interested parties development of the C-123T stopped. However, it concluded the life of the C-123 by making it the only aircraft (at least this is claimed) to operate under jet, internal combustion and turboprop engine power, and as a glider,<ref>The versatile DC-3/C-47 family has operated as a glider and under turboprop power, but not under jet power.</ref> during its history.

===Black Spot and other special military C-123s===
During the conflict in Vietnam, a number of C-123s were modified for specialized roles. Most of these modifications were on a one- or two-aircraft level. Only the usage of C-123s as "flare ships" to illuminate targets for fixed wing AC-47 and AC-119G were more numerous. These aircraft, operating under the call-sign ''Candle'' were flown by the USAF's 14th Special Operations Wing.

thumb|NC-123K "permanent test" model used over the [[Ho Chi Minh Trail. It was outfitted with FLIR, LLTV, laser rangefinder, and cluster bomb dispensers.]]

A single C-123B was tested as a possible replacement for the ''Candle'' aircraft, with its rear loading ramp removed and replaced with a large box with 28 large lights. The airplane could continuously light a 2 mile circle from an altitude of 12,000 feet. This aircraft, under the provisional designation '''NC-123B''' was dropped because the lights, fixed to the aircraft, made it far easier for enemy gunners to track compared to the earlier flare ships.

The "Candle" aircraft had an extended life when several UC-123K's were transferred to Nakhon Phanom Royal Thai Air Force Base in Thailand.  During that period, it was used as a flare ship as well as a forward air control (FAC) aircraft.  The flare duties were generally used for troops in contact (TIC) while the FAC mission directed air strikes in Laos over the Ho Chi Minh trail.

Another NC-123B was used as a radio relay aircraft over the Ho Chi Minh trail, with equipment to read the signals from various sensors on the ground designed to pick up enemy truck activity.

{{Aereo militare
|nome=Fairchild C-123B Provider
|immagine=C123.jpg
|didascalia=Un C-123 dell'USAF
|ruolo=aereo da trasporto
|equipaggio=3
|data_primo_volo=14 ottobre 1949
|data_entrata_in_servizio=1 settembre 1954
|costruttore=Fairchild
|esemplari=302
|lunghezza=23,09 m
|altezza=10,39 m
|apertura_alare=33,53 m
|superficie_alare=113,62 m²
|peso_a_vuoto=13.562 kg
|peso_carico=
|peso_max_al_decollo=27.216 kg
|motore=due Pratt & Whitney R-2800-99W Double Wasp a doppia stella
|potenza=2.331 CV
|velocità_max= 330 km/h
|autonomia= 2.365 km
|tangenza=8.840 m
|capacità=62 passeggeri
|altro=
|note=
}}
Il '''Fairchild C-123 Provider''' è stato un'importante statunitense durante gli anni '50 e '60. Era una macchina dall' aspetto aggraziato e dalla straordinaria somiglianza con il successivo Alenia G.222, anche se la differenza tra un trasporto postbellico di prima generazione ed uno di seconda non è trascurabile, essenzialmente grazie ai motori turboelica più potenti e leggeri, che consentono anche una riduzione della superficie alare complessiva.

==Sviluppo==

Il C-123 venne pensato inizialmente con il nome di MS-Avitruc ("Camion dell'aria") dalla C.A.C., specializzata in alianti d'assalto e trasporto. Presto il nome venne cambiato in '''XC-123''', e da qui il mezzo decollò per la prima volta nell'ottobre USAF lo prendesse in considerazione come aeroplano da trasporto leggero e ne ordinò 5 esemplari.

Ma l'incapacità della ditta originaria di soddisfare in fretta tale ordine fece passare il progetto alla Fairchild, che alla fine del 1953 assunse il comando del programma. Alla fine di una fase di sviluppo, che vide l'allungamento della coda con una pinna dorsale di grandi dimensioni, il C-123 volò finalmente nella sua forma definitiva nel 1954.

Il nuovo aereo venne ordinato in 302 esemplari destinati al TAC (Tactical Air Command).

==Tecnica==

Il C-123, nella sua versione tipica '''C-123B''', era un aereo da trasporto tattico, con una struttura che è stata presa a lungo come modello per i successivi aerei tattici. La struttura era in lega leggera, la ali erano ad alto allungamento, di struttura semplice, a pianta rettangolare anche se con leggero angolo sia in entrata che in uscita. Le ali erano sistemate in posizione alta sulla tozza fusoliera, che era caratterizzata da un tozzo muso e una lunga coda, con la fusoliera marcatamente rialzata nel settore posteriore. Questo terminava con un piano di coda orizzontale, e uno verticale, alto e con un lungo bordo d'attacco per migliorare la stabilità.

Il vano di carico poteva trasportare 7,2 tonnellate e poteva trasportare sia personale che materiali pesanti, grazie alla rampa di carico posteriore.

I motori, la principale differenza rispetto agli alianti che erano la specialità della C.A.C., erano due radiali Pratt & Whitney R-2800 da 2500 cavalli, muniti di elica tripala metallica a passo variabile.

==Versioni==

Molte delle versioni studiate non ebbero seguito, è ma è comunque interessante citarle:

*'''YC-123D''': versione dotata di sistema di soffiaggio dello strato limite, che migliorava le prestazioni STOL
*'''YC-123E''': dotato di fusoliera galleggiante per essere usato come una sorta di idrovolante
*'''YC-123H''': dotato di pneumatici speciali, carrello a carreggiata larga, due turbogetti J85 ausiliari sotto le ali
*'''C-123K''': 180 esemplari vennero dotati di due turbogetti J85 ausiliari in gondole subalari e miglioramenti all'impiantistica. Spesso erano dotati anche di serbatoi ausiliari sotto l'ala.
*'''C-123J''': dotato addirittura di sei reattori ausiliari, ideato per operare in climi artici, con prestazioni di decollo e atterraggio corti elevatissime
*'''UC-123K''': dotato di irroratori per agenti defolianti
*'''N-123K''': dotato di sensori per la sorveglianza notturna