Lockheed Constellation C-121C

The US Air Force already operated L-749-series Constellations (the C-121A) when, in 1951, it ordered 33 Super Constellations of the L-1049F model, the military version of the stretched airliner, and designated them C-121C; Lockheed identified them as L-1049F-55-96. They were close relatives of the Navy's R7V-1, ordered in 1950, and resembled it in almost every respect except one detail visible from outside: the C-121C had square cabin windows instead of the naval aircraft's round ones.

The order brought improvements aimed at a long-range military transport. The structure was reinforced so that turboprops could be fitted if they were ever needed, the aircraft had an auxiliary power unit, and it flew on turbo-compound Wright R-3350s, which recover energy from the exhaust through turbines. The cabin was convertible: it could take 75 passengers, 72 fully equipped troops or 47 stretchers for medical evacuation, and the seats could be stowed under the floor when the aircraft was used for cargo. The technical sheet published by the Historical Aircraft Restoration Society (HARS) for the L-1049F/C-121C lists 18-cylinder R-3350-93A engines with three power-recovery turbines, rated at about 2,900 to 3,400 bhp depending on fuel, reversible three-blade Hamilton Standard propellers, a maximum fuel capacity of 24,790 litres and a maximum take-off weight of 54,500 to 62,400 kg depending on the fuel used.

The first C-121C flew in 1955 and deliveries began in August that year to the Atlantic Division of the Military Air Transport Service (MATS). The history of aircraft 54-0157 compiled by The Lockheed File shows what that service looked like: the aircraft joined the 41st Air Transport Squadron (Heavy) of the 1608th Air Transport Wing at Charleston AFB, South Carolina, a squadron that had moved from Wiesbaden and was converting from the C-54 to the C-121. The wing's scheduled flights carried passengers, cargo and mail to Rhein-Main, Châteauroux, Nouasseur, Tripoli, Dhahran, the Azores, Newfoundland, Labrador, Bermuda, Puerto Rico, the Canal Zone, Trinidad, Rio de Janeiro and Ascension Island. From July to December 1960 the wing also supported downrange missile tracking for the Air Force Missile Test Center at Cape Canaveral.

The National Air and Space Museum describes the original configuration of its own example, 54-0177, as an over-water cargo and passenger transport with eight crew and accommodation for up to 80 passengers; it reached Charleston in March 1956 and was likewise assigned to the 1608th Wing.

The C-121Cs later passed to the Air National Guard. The 183rd Aeromedical Airlift Squadron of the Mississippi Guard, at Jackson, was the first Guard unit to fly the type when it received 54-0157 in July 1962, and in time it added general transport missions to its medical work. In February 1967 the aircraft moved to the West Virginia Guard's 167th Military Airlift Group at Martinsburg, and in March 1972 to the Pennsylvania Guard's 193rd Tactical Electronic Warfare Group at Harrisburg. That group flew psychological operations in Vietnam with four EC-121S converted from C-121Cs; 54-0157 was not converted and stayed on as a support transport, and from May to August 1976 it deployed to Torrejón, Spain, in support of the 401st Tactical Fighter Wing. When the 193rd converted to the EC-130E, its Constellations were progressively ferried to Davis-Monthan from late 1976.

HARS gives slightly different dates for the same aircraft: delivery on 6 October 1955, transfer to the Mississippi Guard on 25 July 1962 and to the West Virginia Guard on 14 February 1967. The Lockheed File instead dates its delivery at Burbank to July 1955. The online encyclopedia entry on the C-121 places the type's retirement in 1973, yet the two documented survivors remained in service until 1977.

The batch of 33 produced several conversions: four were refitted as VC-121C VIP aircraft, six as EC-121S television and radio broadcast relays, two as EC-121C Microwave Airborne Radio Communications (MARCOM) aircraft and one as a DC-121C observation aircraft.

54-0157 (construction number 4176) arrived at the Davis-Monthan storage centre on 28 March 1977 with 18,452 flying hours; its last depot-level maintenance dated from November 1971. Storage maintenance stopped in 1981 and the aircraft was rated as scrap; it had lost most of its engine accessories and instruments, and birds nested inside for years, which, according to HARS, put the scrap merchants off. In 1990 members of the Australian society collecting Neptune spares in Tucson spotted it and decided to recover it, and in November 1991 it was placed in their care.

Restoration began in 1992 at the Pima Air & Space Museum, to which it was towed from Davis-Monthan, and relied entirely on volunteers who had to travel to Arizona again and again, with support from Qantas: 16,000 man-hours, 800,000 dollars raised and 47 team trips averaging 14 days each. The engines ran again in April 1994 and on 23 September 1994 the aircraft flew once more, under the temporary registration N4115Q and fitted with tip tanks, after nearly eighteen years on the ground; it was registered VH-EAG the same day. The delivery flight left Tucson on 23 January 1996 for Oakland, where a fuel leak held it for a day, and continued via Honolulu, Pago Pago and Nadi to Sydney, where it landed on 3 February 1996 after an incident-free 39.5 hours of flying. The aircraft had been bought by the Museum of Victoria and ownership passed to HARS the following year; since November 2002 it has been based at Albion Park, Wollongong, and years later it returned there freshly repainted after a visit to Wagga.

HARS points out that its aircraft and the Breitling-sponsored Super Constellation in Switzerland were built next to each other on the production line, as numbers 4176 and 4177. The Swiss aircraft, formerly 54-0153, flew with the Super Constellation Flyers Association until 2016 and was put up for sale in April 2023, leaving the Australian machine as the only flying L-1049.

The other famous survivor left military service near the end of 1977 and was stored until 1981. It was meant to join a small fleet of passenger Constellations flying between Los Angeles and Reno under the Classic Air name, but the venture failed to win FAA approval and the aircraft sat idle. Darryl Greenamyer, who had acquired two of them, then negotiated with the National Air and Space Museum to trade the C-121C, registered N1104W, for two Grumman HU-16 Albatross amphibians. It is now displayed at the Steven F. Udvar-Hazy Center beside Dulles airport, in the markings of the West Virginia Air National Guard.

Like other retired C-121s and R7V-1s, some C-121Cs ended up with small civilian cargo operators. The last were Dominican Republic airlines flying to Miami with surplus military Constellations bought from Davis-Monthan, until in 1993 the FAA barred them from the United States on safety grounds.