The F-100C fighter-bomber was the first fully combat-capable version of the Super Sabre, and was the first version of the Super Sabre to serve with the USAF in really large numbers.
In October 1952, even before the YF-100A had taken off on its first flight, the USAF asked NAA to look into the possibility of developing wings for the Super Sabre that could carry fuel. In July of 1953, the USAF asked that the new "wet" wing could be made sufficiently strong enough to carry additional external ordinance. This concept eventually emerged as the F-100C fighter-bomber version of the Super Sabre.
On December 30, 1953, the USAF revised the original F-100A production order and stipulated that the last 70 planes on that order be completed as fighter-bombers under the designation F-100C (company designation NA-214). On February 24, 1954, the Air Force ordered an additional 230 F-100Cs.
In order to provide a prototype for the F-100C project, the fourth production F-100A (serial number 52-5759) was taken out of the test program and modified. However, because of the difficulty in incorporating integral fuel tanks in an already-constructed airframe, 52-5759 remained a dry-wing aircraft. It flew for the first time on July 26, 1954. This aircraft was delivered with the short vertical tail of initial F-100A aircraft, with the taller vertical tail being fitted later.
The F-100C introduced wing modifications that added hard points on the lower surface that could be fitted with removeable pylons that could hold either fuel tanks or weapons. These six underwing stations could accommodate a wide variety of stores including fuel tanks, napalm, bombs, up to a dozen five-inch HVARs (high-velocity air rockets), and even "special stores" such as the MK-7 nuclear weapon. A total of 5000 pounds could be carried on these stations. The wing was locally strengthened to withstand the sudden shock of weapons release.
In order to accommodate the fuel in the "wet" wing, the wing's integral systems had to be redistributed. A leak proofing system was devised in which all bolts that fastened skin to spars were sealed with injected material. In the final design, the F-100C "wet" wing could carry 451 US gallons of fuel. Total internal fuel capacity was 1602 gallons, as compared with 744 gallons for the F-100A.
The F-100C had provision for single-point ground refuelling, a major improvement over the gravity-filling of the fuselage tanks in the F-100A. A wing-mounted detachable refuelling probe was added which made the F-100C capable of in-flight refuelling.
The first production F-100C (53-1709) rolled off the line on October 19, 1954. It was conditionally accepted by the USAF on October 29, since all Super Sabres were officially grounded at that time pending the fitting of new vertical tails. It took to the air for the first time on January 17, 1955, with NAA test pilot George Hoskins at the controls. It had the original short F-100A tail, but was later fitted with the new taller tail.
On May 27, 1954, an additional USAF contract increased the total number of F-100Cs to 564, more than doubling the initial order. However, on September 27 the contract was amended to stipulate that the last 224 aircraft on the order be completed as F-100Ds.
On October 11, 1954, North American's Columbus, Ohio plant was designated as a second source for Super Sabre production. Columbus-built F-100Cs were designated NA-222 by the company. Air Force designations distinguished Columbus-built machines from California-built machines by using the suffix *NH* rather than *NA*. A contract was let which authorized the construction of 25 F-100Cs at Columbus, followed by 221 F-100Ds. The first of 25 Columbus-built F-100Cs (55-2709) took off on its maiden flight on September 8, 1955.
Provision had been made for an additional pair of 200-gallon drop tanks to supplement the pair of 275-gallon drop tanks usually carried. However, the addition of these smaller tanks caused some longitudinal stability problems, especially at high cruising speeds. For a while, it seemed that the only cure for this problem would be yet another time-consuming and costly increase in the surface area of the vertical tail. Paradoxically, the use of larger fuel tanks cured the problem, and both the 275- and the 200-gallon tanks were replaced by a single pair of 450-gallon tanks. However, these bigger tanks were costly and were rarely carried. A change to 335-gallon tanks was later made.
F-100C deliveries to TAC began in April of 1955. The first outfit to receive the F-100C, the 450th Fighter Day Squadron at Foster AFB in Texas, became fully operational on July 14, 1955. By the end of 1956, F-100Cs were serving with the 8th Fighter-Bomber Group in the Fifth Air Force in Japan.
The first few F-100Cs were powered by the J57-P-7, rated at 9700 lb.s.t. dry and 14,800 lb.s.t. with afterburner. This engine was soon replaced on the production line by the J57-P-39 with similar rating. However, most F-100Cs (from the 101st machine and onward) were powered by the J57-P-21, an upgraded version of the J57-P-7. The -21 was rated at 10,200 lb.s.t. dry and 16,000 lb.s.t. with afterburner. This engine provided more thrust at higher altitudes, and increased the speed at altitude by about 40 mph and reduced the time to climb to 35,000 feet by about ten percent.
One of the more serious defects of the F-100C was that this aircraft, like the F-100A before it, tended to yaw and go into an uncontrollable roll at high speeds. Beginning with the 146th production F-100C, hydraulically-activated and electrically-controlled yaw dampers were incorporated on the production line. This innovation seemed to help to alleviate this problem, and was retrofitted to earlier F-100Cs.
Beginning with the 301st F-100C, pitch dampers were added to the horizontal stabilizer control system. This helped to damp out longitudinal oscillations, which had been an ongoing problem with the Super Sabre.
The J57 engine of the F-100 suffered from a problem with compressor stalls. A partial cure for this problem was the installation of a pressure bleed-off which helped to release the accumulated gases and to prevent internal explosions.
On August 20, 1955, Col. Horace A. Hanes flew a F-100C to set a new world's air speed record. In two runs made at an altitude of 40,000 feet in opposite directions over a 15-25 km course laid out on the Mojave Desert, he averaged 822.135 mph. This was the first supersonic world's speed record. It was also the first record set at high altitude, all previous record-setting runs having been made at very low altitudes.
On September 4, 1955, Col. Carlos Talbott flew his F-100C across the USA from coast to coast, a distance of 2325 miles at an average speed of 610.726 mph. For this feat, Col. Talbott was awarded the Bendix Trophy.
A total of 476 F-100Cs were built, the last example being accepted in July of 1956.
More than 150 F-100Cs served in Europe. Major bases were at Bitburg, Furstenfeldbruck, Landstuhl, and Hahn in West Germany, plus Sidi Slimane in Morocco and Camp New Amsterdam in the Netherlands.
The service of the F-100C with the USAF was relatively brief, being rapidly superseded by the F-100D. Ex-USAF F-100Cs were passed along to the Air National Guard (ANG), the first squadrons receiving the type in mid-1959. Most of the F-100Cs remaining in the Air Force active inventory in the late 1950s served exclusively in training roles.
On October 1, 1961, President Kennedy mobilized the ANG in response to the Berlin Crisis. Many of these mobilized ANG squadrons were transferred to Europe to augment NATO, but three ANG squadrons equipped with newly-received F-100Cs stayed in the United States. This included the 120th TFS, the 121st TFS of the Washington DC ANG and the 136th TFS. All of these ANG squadrons were demobilized in August of 1962.
By mid-1966, 210 F-100Cs were in service with the ANG. However, on January 25, 1968, in response to the *Pueblo* incident, President Johnson mobilized a major portion of the Selected Reserve Force, which included eight ANG squadrons equipped with F-100Cs. The last of these F-100Cs were phased out in March of 1970, and by late 1970 ANG F-100C strength was back up to 210 aircraft.
The only F-100Cs to fly in combat in Vietnam flew with ANG units which had been called up for that conflict. A total of four ANG squadrons (from Colorado, New York, Iowa, and New Mexico) flew F-100Cs in Vietnam.
The USAF Thunderbirds flight demonstration team operated F-100Cs from 1956 until 1964. Thunderbird F-100Cs were painted in picturesque red, white, and blue colors, with the characteristic Thunderbird being painted on the aircraft's belly. They were replaced by F-100Ds in 1964.
A total of 476 F-100Cs were built. The safety record of the F-100C was not all that good, some 85 of them being involved in major accidents.
As they left operational service, a few F-100Cs ended up serving in test roles. NACA (and later NASA) operated a pair of F-100Cs (53-1712 and -1717) plus one JF-100C (52-1709). The first F-100C was used to test a pitching motion damper. The second F-100C was used to fly chase support. The JF-100C was used for variable stability studies supporting the X-15 and supersonic transport programs. F-100C 54-1964 was loaned to the Ames Research center for tests of a boundary layer control system. It had a thicker inlet lip, a drooped leading edge, and ducting to carry bleed air from the engine compressor to the wing leading edge.
53-1709/1778 North American F-100C-1-NA Super Sabre (NA-214) 54-1740/1769 North American F-100C-1-NA Super Sabre (NA-217) 54-1770/1814 North American F-100C-5-NA Super Sabre (NA-217) 54-1815/1859 North American F-100C-15-NA Super Sabre (NA-217) 54-1860/1970 North American F-100C-20-NA Super Sabre (NA-217) 54-1971/2120 North American F-100C-25-NA Super Sabre (NA-217) 55-2709/2733 North American F-100C-10-NH Super Sabre (NA-222)
Engine: One Pratt & Whitney J57-P-21 turbojet, 10,200 lb.s.t. dry and 16,000 lb.s.t. with afterburning. Dimensions: Wingspan 38 feet 9 inches, length 47 feet 1 1/4 inches, height 15 feet 6 inches, wing area 385 square feet. Performance: Maximum speed 760 mph at sea level, 924 mph at 35,000 feet. Initial climb rate 21,600 feet/minute, climb to 35,000 feet in 2.3 minutes. Service ceiling 38,700 feet, combat ceiling 49,100 feet. Normal range 572 miles, maximum range 1954 miles. Fuel capacity 1702 US gallons internal, total of 2139 US gallons with external tanks added. Weights: 19,270 pounds empty, 27,587 pounds gross, 32,615 pounds maximum takeoff. Armament: Four 20-mm Pontaic M-39 cannon, plus external loads of up to 5000 pounds of bombs, rockets, or fuel tanks carried on six underwing hardpounts.