THE 456th FIGHTER INTERCEPTOR SQUADRON
THE PROTECTORS OF S. A. C.
The North American F-100 "Super Sabre"
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North American F-100 "Super Sabre" YF-100, -A and -C
The F-100 was the USAF's first operational aircraft capable of flying faster than the speed of sound (760 mph) in level flight. It made its initial flight on May 25, 1953 and the first production aircraft was completed in October 1953. North American built 2,294 F-100s before production ended in 1959.
Designed originally to destroy enemy aircraft in aerial combat, the F-100 later became a fighter-bomber. It made its combat debut during the Vietnam conflict where it was assigned the task of attacking such targets as bridges, river barges, road junctions, and areas being used by infiltrating enemy soldiers.
The F-100C, which made its first flight in 1955, featured such advances as an in-flight refueling system, provisions for extra fuel drop tanks and bombs under the wings and an improved electronic bombing system.
TYPE Number built/Converted Remarks YF-100
6 conv. from F-100A
3 built as YF-107A
6 production blocks
Click on Picture to enlarge
Span: 38 ft. 10 in.
Length: 53 ft. 11 in. (with pitot boom extended); 47 ft. (with boom folded)
Height: 15 ft. 6 in.
Weight: 36,549 lbs. max.
Armament: Four M39 20mm cannons and 42 2.75-inch rockets or 5,000 lbs. of bombs
Engine: One Pratt & Whitney J57-P-21 of 16,000 lbs. thrust with afterburner
Maximum speed: 900 mph.
Cruising speed: 600 mph.
Range: 1,350 miles
Service Ceiling: 51,000 ft.
Curtest of the US Air Force Museum
The North American F-100 Super Sabre
BY JOE BAUGER
The North American YF-100 Super Saber
The North American F-100 Super Sabre was the first fighter in the USAF active service inventory capable of attaining supersonic performance in level flight. Although it was originally designed strictly for the air superiority role, it came into its own as a fighter-bomber, and flew many of the early combat missions during the Vietnam War.
The quest for a supersonic version of the Sabre began in February of 1949, when Raymond Rice and Edgar Schmued of North American Aviation began work on a company-financed design study for an advanced version of the Sabre capable of achieving supersonic performance in level flight. This study came up with a proposal for obtaining this performance improvement by increasing the wing sweepback of the standard F-86 to 45 degrees. However, wind tunnel studies indicated that only a relatively small increase in maximum speed would be attained by this change, due to the steep rise in aerodynamic drag that takes place as near-sonic speeds are attained.
Clearly, aerodynamic changes alone would not be sufficient to achieve supersonic speeds in level flight. More power would be needed--a lot more power. To this end, the Allison Division of General Motors offered an upgraded J35 turbojet rated at 9000 lbs t, which nearly doubled the thrust of the J47 engine of the F-86. General Electric proposed an advanced version of the J47 rated at 9400 lb.st. dry and 13,000 lbs t with afterburning.
On Sept 14, 1949, NAA decided that they would concentrate their efforts on the development of an improved version of the F-86D all-weather interceptor with the goal of achieving supersonic performance. It was to be powered by the Advanced J47 proposed by General Electric. A maximum speed of Mach 1.03 at 35,000 feet was envisaged. The "Advanced F-86D" (as the aircraft came to be known) had a 45 degree wing sweep and an area-ruled fuselage. However, the USAF rejected this idea, proposing that NAA design a day fighter instead.
North American decided to try and give the USAF what it asked for, and responded with a proposal for an "Advanced F-86E", which was to be a high-performance day-fighter. The Advanced F-86E that emerged in January of 1951 was similar in many respects to the Advanced F-86D, but had a slimmer fuselage and featured a nose air intake without a radome on the top. The USAF rejected this idea as well, but indicated that the idea might be reworked into an air-superiority fighter.
The next proposal was known by the company as the Sabre 45, the "45" indicating the angle of wing sweepback. It combined features of the Advanced F-86D and the Advanced F-86E, but was to be powered by the new Pratt & Whitney J57-P-1 turbojet, rated at 15,000 lb.st. with afterburner. Maximum speed was estimated at Mach 1.3 (860 mph) at 35,000 feet and combat radius was 670 miles. Estimated combat gross weight was 23,750 pounds. Armament was to be a quartet of 20-mm T-130 cannon.
The Sabre 45 finally succeeded in attracting the interest of the USAF. NAA asked that the USAF purchase two prototypes of the Sabre 45, one to be used for aerodynamic testing and the other to be used for armament trials.
In October of 1951, the USAF Council decided to press for the development of the Sabre 45 proposal, in spite of some misgivings of key development personnel who claimed that the design would be too costly and complex for a basic day fighter. With the Korean War as a reminder of the perilous state of USSR/US relations, the Air Force Council wanted the Sabre 45 in service in a hurry. They thought that two prototypes were not enough to achieve early operational status and recommended that the plane be purchased in quantity and full production be initiated even before initial flight testing was completed. This is a high-risk philosophy, one which would give the Air Force a new plane in a hurry if everything went as planned, but one which would risk the high costs and long delays of a lot of in-service modifications should unexpected problems turn up during flight testing. However, considering the pressures of the hot war in Korea and the cold war with the Soviet Union, the risk was considered worth taking. On November 1, 1951, the Air Force issued a Letter Contract for two Sabre 45 prototypes, plus 110 production aircraft.
On November 9, the Sabre 45 mockup was inspected. The Mockup Board received more than a hundred configuration change requests, and they identified several armament deficiencies and requested a number of modifications that would improve the capabilities of the aircraft.
Work on an F-100A production version was begun under the company designation of NA-192 on November 20, 1951. On December 7, 1951 the USAF officially designated the Sabre 45 as the F-100, the first of the Century Series of fighters. The two prototypes were designated YF-100 by the USAF and NA-180 by the company.
A Letter Contract for two YF-100 prototypes was issued on January 3, 1952. On February 11, 1952, the Air Force issued another Letter Contract for 23 production F-100As with Fiscal Year 1952 funds.
Following the mockup inspection, North American reshaped the fuselage with an even higher fineness ratio and provided an extended clamshell-type cockpit canopy. The horizontal tail was moved to a position below the chord plane of the wing, in the hope that it would keep the tail clear of the wing wake at high angles of attack and would help to prevent the dangerous tendency of a swept-wing aircraft to pitch up suddenly and violently following a stall. This sometimes deadly phenomenon had come to be known as the "Sabre dance", and had been the cause of numerous accidents in the F-86. YF-86D serial number 50-577 was experimentally modified to check out this new low-set horizontal tail arrangement.
On June 23, 1952, the USAF approved the proposed changes, but asked NAA to consider the installation of external weapons racks and to substitute non-self-sealing tanks for existing bladder tanks to save 400 pounds of weight.
During the final design stage, NAA engineers made several changes to reduce drag and increase engine thrust. They changed the air intake lip so that it had a sharp edge in order to improve the air flow and to deliver higher-energy air to the engine at supersonic speeds. The nose was made nine inches longer. The thickness/chord ratio of the horizontal and vertical tails was decreased to 0.035. This last change was scheduled for production aircraft, but was too late to appear on the two prototypes. These changes were approved on August 26, 1952. At that time, the USAF authorized the procurement of 250 additional F-100As.
The YF-100 that finally emerged from these design changes was sufficiently different from that originally planned that it was re-designated YF-100A. The YF-100A had a wing thickness/chord (t/c) ratio of 0.082, as compared to the F-86's 0.10 t/c ratio. A glove airfoil section was added to the wing leading edge which reduced the wing t/c ratio still further to 0.07. The ailerons were mounted inboard on the wing rather than near the tips in order to reduce the tendency of the wing to twist during aileron deflection at high speeds. The YF-100A was somewhat unusual for its time in that no wing flaps were provided. However, the wing leading edge did have five-segment automatic slats that were actuated by aerodynamic forces. These slats were intended to increase lift at takeoff, to delay wing buffet, to improve lateral control near the stall, and to permit tighter turns.
A retractable speed brake was mounted on the fuselage belly. The tall and narrow vertical fin was swept back, and was provided with a thin rudder.
No fuel tanks were mounted in the wing, all of the internal fuel being accommodated inside the fuselage in five non-self-sealing bladder tanks having a total capacity of 750 US gallons. Two under wing drop tanks each carrying 275 US gallons could be fitted.
The main wheels retracted inwards into the fuselage, and the twin nose wheels retracted backwards into the fuselage.
Heat-resistant titanium was used in the initial design stage, marking the first time that this metal had been used in large quantities in an airplane. In fact, North American actually used 80 percent of all the titanium produced in the United States until 1954 in the manufacture of the Super Sabre. Titanium is an extremely strong and light metal and is more resistant to heat than is aluminum. However, it is rather brittle and difficult to machine, and the extensive use of titanium sent the cost of Super Sabre manufacture through the roof.
The armament was to consist of four T-160 (later M39) cannon, two on each side of the fuselage below the cockpit. Ammunition capacity was 275 rpg. An A-4 ranging gunsight was to be fitted which computed the lead automatically, aided by ranging information from a radar antenna mounted inside the upper nose inlet lip and covered by a flush-mounted dielectric panel.
The engine for the YF-100A was the Pratt & Whitney J57-P-7, rated at 9220 lb.st. dry and 14,800 lb.st with afterburner. This engine was, however, derated from these numbers and was not tuned up to give its full power. On August 26, 1952, the USAF increased its order to 273 aircraft, plus one static test example.
As the first YF-100A was nearing completion, the Air Force recognized that two prototypes would not be sufficient for the test program, and they decided that the first ten F-100As off the line would be used as test aircraft as well.
The first YF-100A (52-5754) was completed on April 24, 1953. It was moved in high secrecy from the Los Angeles factory out to Edwards AFB. Company test pilot George S. Welch made the maiden flight on May 25, 1953. The YF-100A exceeded the speed of sound on its first flight.
On July 6 the YF-100A achieved a speed of Mach 1.44 in a long dive from 51,000 feet. However, on the early test flights, some problems were encountered with rudder flutter. The installation of hydraulic rudder dampers solved this problem.
USAF test pilots found that the YF-100A outperformed any other production fighter in the Air Force, but they also found that there were some serious shortcomings that might cause problems upon introduction into service. The visibility over the nose was poor during takeoff and landing. The longitudinal stability in high-speed level flight was considered inadequate. The low-speed handling was rather poor, and there was a tendency of the YF-100A to yaw and pitch near the stall, the left wing dropping uncontrollably. The climbing rate was too slow without afterburner--it took 16 minutes to get to 40,000 feet. In addition, the landing was difficult and the touchdown speed was high.
Phase II tests were completed by September 15, 1953, at which time the YF-100A had made 39 flights tasting a total of 19 hours, 42 minutes.
The second YF-100A (52-5755) flew on October 14, 1953.
In order to show off the Super Sabre, the USAF decided to use it to break the world's speed record. At that time, the world speed record was held by the Douglas XF4D-1 Skyray which had averaged 753.4 mph for two runs in each direction over a three-km straight course. In order to set a new record, the Super Sabre had to top the previous mark by at least one percent, which meant that the aircraft had to average at least 760.9 mph over the 3-km course. Lt. Col. Frank K. (Pete) Everest was chosen to make the attempt. On his first try over a 3-kilometer course laid out over the Salton Sea, Lt. Col. Everest flying YF-100A 54-5754 averaged 757.75 mph on the required four runs, faster than the Skyray but not one percent faster, so it did not count. It was decided to make another try over a different course, a 15-kilometer course where the one-percent margin rule would not apply. Under the rules of the Federation Aeronautique International (FAI), the fastest speed over either course counted as the official world speed record. On October 29, 1953, Lt.Col. Everest averaged 755.149 mph to set a new official world speed record. Throughout the entire record-breaking run, Lt. Col. Everest kept his YF-100A within 100 feet of the ground. This was the last world speed record set at low altitude.
Serials:52-5754/5755 North American YF-100A Super Sabre
Engine: One Pratt & Whitney XJ57-P-7 turbojet, 9500 lb.st. dry and 13,200 lb.st. with afterburning. Dimensions: Wingspan 36 feet 7 inches, length 47 feet 1 1/4 inches, height 16 feet 3 inches, wing area 385 square feet. Performance: Maximum speed 660 mph at 43,350 feet. Landing speed 160 mph. Initial climb rate 12,500 feet/minute. Service ceiling 52,600 feet. Normal range 422 miles, maximum range 1410 miles. Fuel capacity 1307 US gallons. Weights were 18,135 pounds empty, 24,789 pounds gross.
The North American F-100A Super Saber
The F-100A (company designation NA-192) was the first production version of the Super Sabre. The first F-100A (52-5756) was completed on September 25, 1953, and made its first flight on October 29, George Welch again being at the controls. This was only two weeks after the maiden flight of the second YF-100A prototype, indicative of the speed with which the Super Sabre program was being rushed along.
The F-100A was similar in most respects to the YF-100A, but had a shorter and more stubby vertical tail with increased chord. There was a fuel vent tube mounted on the fin's trailing edge at the midpoint. There was a small rudder fitted to the trailing edge of the fin below the vent tube.
The mission of the F-100A was seen as that of daylight air superiority, and the aircraft was pictured as the natural replacement of the F-86A/E/F Sabre of Korean War fame. The armament of the F-100A consisted of four 20-mm Pontiac M-39 cannon installed in the lower fuselage below the cockpit and carrying 200 rounds per gun. The M-39 had been tested in Korea on modified F-86Fs as the T-160, and fired 1500 rounds per minute at a muzzle velocity of 3300 feet per second.
At the end of November of 1953, the first three F-100As were delivered to George AFB to re-equip the 436th Fighter Day Squadron of the 479th Fighter Day Group of the TAC. This Group became operational with the F-100A on September 29, 1954.
During late 1953, slippages in the Republic F-84F Thunderstreak program caused the Tactical Air Command (TAC) to recommend that a version of the Super Sabre be developed with a secondary fighter-bomber capability. On December 31, 1953 the USAF directed that the last 70 F-100As on the order be modified as fighter-bombers and redesignated F-100C. The fourth production F-100A (52-5759) was chosen for modification as the prototype for the F-100C. The wingtips were extended twelve inches on either side, improving the roll characteristics and decreasing stalling speed. These wingtip extensions were considered sufficiently advantageous that they were incorporated into the F-100A production line beginning with the 101st example.
The first F-100As had been delivered with a short vertical tail. In service, USAF pilots reported stability and control problems with their F-100As, and their suspicion was that the vertical tail was not large enough to maintain adequate directional stability. This problem was especially severe when the under wing drop tanks were being carried. Consequently, most of these early F-100As were never flown to the limits of their performance envelopes.
The 11th F-100A introduced a retractable tail skid to prevent accidental damage to the rear fuselage underbelly during landings at high angles of attack.
The 24th F-100A introduced a yaw damper system. Provisions for a pitch damper were installed in the 154th and subsequent aircraft.
The F-100A had been rushed into service with unseeing haste, often over the objections of Air Force flight crews who found that the Super Sabre had some serious problems that were not being adequately addressed. Disaster struck on October 12, 1954. On that day, veteran test pilot George Welch was carrying out a maximum performance test dive followed by a high-G pullout with the ninth production F-100A (52-5764) when his aircraft disintegrated in midair. Welch was able to eject, but his injuries proved to be fatal since his airplane had broken at the cockpit area and had sent chunks of metal tearing into his body. On November 8, visiting RAF officer Geoffrey D. Stephenson was killed at Elgin AFB when his F-100A went out of control and crashed. On November 9, Major Frank N. Emory's F-100A (52-5771) went out of control and crashed during a practice gunnery mission over Nevada. Fortunately, Major Emory was able to eject safely. On November 10, the USAF grounded the entire F-100A fleet, which by this time numbered about seventy aircraft. A further 108 Super Sabres had been completed and were awaiting delivery at the factory.
After an exhaustive investigation, the source of the F-100A's stability problems was traced to its new shorter tail, which USAF test pilots had suspected all along. A decision was made to switch back to the original taller tail of the YF-100A. 27 percent more vertical tail area was added, which served to delay the onset of instability to speeds above Mach 1.4, which were outside the F-100A's performance envelope. The aspect ratio of the vertical tail was also increased. With these changes, the height of the modified F-100A increased to 15.34 feet. The wingtip extensions planned for the F-100C were adopted as standard for the F-100A, increasing the wingspan from 36.78 feet to 38.78 feet and the wing area from 376 square feet to 385.21 square feet. The artificial feel systems for the aileron and stabilizer powered controls were modified.
These changes seemed to do the job, and the existing F-100As were retrofitted with the changes. The first aircraft to complete the modification program was the 34th Super Sabre, and the first batch of 11 modified aircraft was delivered to NAA Engineering Flight Test. Because of the rapid rate at which production had been built up, it was not until the 184th airframe that these modifications could be introduced on the assembly line. Earlier aircraft (68 accepted and 112 completed) were retrofitted in hangar areas. Deliveries of the modified F-100A began from the Los Angeles factory in the spring of 1954. The grounding order on the F-100A was finally lifted early in February of 1955.
Initial operational capability with the new and improved F-100A was achieved in September of 1955 by the 479th Fighter Day Wing at George AFB. Late in 1955, pilots from the USAF Air Proving Ground Command at Elgin AFB in Florida participated in *Project Hot Rod* to evaluate the suitability of the F-100A for operational service. Their conclusions were similar to those of earlier evaluations--the performance was good but there were still some major operational deficiencies which prevented the F-100A from being a really good day fighter. Consequently, the F-100A was never very popular with its flight crews.
F-100As from number 167 onward had the J57-P-39 engine, which had the same thrust as the P-7.
The ejector seat of the F-100A received a rather spectacular test of its effectiveness on February 26, 1955. On that day, company test pilot George F. Smith was doing a low-altitude speed run in F-100A serial number 53-1659 when his plane suffered a hydraulic lock which resulted in an uncontrollable dive. He was forced to eject at Mach 1.05 and was severely injured, but recovered to fly again. I think that Smith was the first pilot to eject at supersonic speed and survive.
The last F-100A was delivered to the USAF in July of 1955. A total of 203 F-100As were built.
Since the F-100A was not considered as a truly effective air superiority fighter, the service life of the type with the USAF was rather brief, most aircraft being phased out of the active USAF inventory beginning in 1958. They were then transferred to the Air National Guard or placed in storage at Nellis AFB.
In mid-1959, fifteen of these stored F-100As were transferred to the Chinese Nationalist Air Force on Taiwan. In 1960, 65 more F-100As were sent to China.
The first Air National Guard unit to receive the F-100A was the 188th TFS of the New Mexico ANG, which received these planes in April of 1958. In 1960, the ANG reached its peak inventory of 70 F-100As. During the Berlin crisis of 1961, numerous Air National Guard and Air Force Reserve units were mobilized and called to active duty. This had the effect of returning some of these ex-USAF F-100As to active service.
In spite of their deficiencies, some F-100As which had been operated by these activated ANG units were retained by the USAF even after the ANG personnel were released from active duty in early 1962 following the end of the Berlin crisis. Most of the F-100As retained by the USAF were used for aircrew training and were not considered as being combat-capable aircraft.
Thirty-eight of these reactivated F-100As were transferred to Nationalist China. A total of 118 F-100As were ultimately transferred to the Chinese Nationalist Air Force, which was more than 58 percent of the total F-100A production. Many of these F-100As were upgraded with the vertical tail of the later F-100D before being sent to China.
The F-100A had an abominable safety record, even after the modifications which had corrected the stability problems with the original short vertical tail. About 50 F-100A were lost in accidents while in service, which was about 25 percent of the total F-100A production. The last F-100A finally left USAF service in early 1970. The ANG had lost its last F-100A to attrition in 1967.
The NACA received an early F-100A (52-5778) which it used to perform stability and control tests. NACA test pilot Scott Crossfield flew the F-100A during the late fall of 1954 to determine the flight boundaries where inertial coupling could occur.
Serials of the F-100A:52-5756/5765 North American F-100A-1-NA Super Sabre 52-5766/5778 North American F-100A-5-NA Super Sabre 53-1529/1568 North American F-100A-10-NA Super Sabre 53-1569/1608 North American F-100A-15-NA Super Sabre 53-1609/1708 North American F-100A-20-NA Super Sabre
Engine: One Pratt & Whitney J57-P-7/39 turbojet, 9700 lb.st. dry and 14,800 lb.st. with afterburning. Dimensions: Wingspan 38 feet 9 inches, length 47 feet 1 1/4 inches, height 15 feet 8 inches, wing area 385 square feet. Performance: Maximum speed 760 mph at sea level, 852 mph at 35,000 feet. Initial climb rate 23,800 feet/minute. Service ceiling 44,900 feet, combat ceiling 51,000 feet. Normal range 358 miles, maximum range 1294 miles. Fuel capacity 1294 US gallons. Weights: 18,185 pounds empty, 24,996 pounds gross. Armament: Four 20-mm Pontiac M-39 cannon with 200 rpg. In addition, two underwing stations were provided which could accommodate bombs as large as 1000 pounds in weight.
The North American RF-100A Super Sabre
Six nearly complete F-100As were taken off the production line during September of 1954 and modified as unarmed photographic reconnaissance aircraft under the designation RF-100A. Serials were 53-1545/1548, 55-1551, and 55-1554. The nose armament was completely removed and replaced by five reconnaissance camera systems which looked ahead and to each side of the aircraft. The cameras could not all fit within the existing fuselage contour, and a distinctive bulge had to be added onto the fuselage belly underneath the cockpit in order to accommodate all of this equipment. This bulge extended from below the windshield almost to the wing trailing edge, and was a obvious recognition feature. The RF-100As carried four drop tanks rather than the usual two because the mission profile called for a lot of high-speed flight under afterburner and there was no provision for midair refueling. For some reason, the RF-100A became known as "Slick Chick".
Click on Picture to enlarge
Few photographs of the RF-100A have been published and even fewer details are available about its service. The few photos of the RF-100A that have appeared in print tend to be blurry and indistinct, obviously being copies of copies of copies. There exists a photograph of one RF-100A painted with the spurious serial number of 53-2600 (actually an F-89 Scorpion serial number). The reason for the reluctance to speak openly about the RF-100A seems to be because this aircraft (along with lots of other types) participated in some rather dangerous reconnaissance missions flown over Soviet-occupied territories in Europe during the darkest days of the Cold War. RF-100As would dash at high speed across the Iron Curtain, take their pictures, then beat a hasty retreat before defenses had time to react. Needless to say, very few details are available about these missions. Now that the Cold War is over, perhaps the veil of secrecy that surrounds these missions can finally be lifted.
In late 1961, four of the RF-100As were sent to the Chinese Nationalist Air Force on Taiwan. It is generally believed that these aircraft flew operational reconnaissance missions over the People's Republic of China. The Chinese Nationalist Air Force often passed the information gained by these reconnaissance flights along to US intelligence agencies. Again, there are few details publicly available about these missions.
The North American RF-100A Super Sabre
The F-100B was originally going to be the follow-on to the F-100A. It was pictured as a faster version of the F-100A day fighter, optimized to take maximum advantage of the power offered by the J57 jet engine.
The F-100B project began in 1953 as company design NA-212 for an improved F-100A. On March 4, 1952, North American Aviation management had asked their design team for an estimate of engineering requirements for the F-100B. The F-100B retained the original swept wing planform of the F-100A but had a thinner wing cross section with a 5 percent thickness/chord ratio rather than the 7 percent of the F-100A. An upgraded J57 engine was provided, and the aircraft was to be fitted with a variable-area inlet duct and a convergent-divergent exhaust nozzle. Total thrust of this new engine was to be 16,000 pounds. Dual landing-gear wheels were to be provided which would make operations from unprepared airfields possible. The fuselage was to be area-ruled and was to have an increased fineness ratio. The fuel load was to be carried in integral wing tanks, no provisions being made for the carrying of external fuel tanks. The F-100B was to expected to be approximately the same size and weight as the F-100A, and with the increased power and the aerodynamic refinements that would be made available, a maximum speed of Mach 1.80 at high altitude was anticipated. Production was expected to begin in 1955.
At the same time, North American began to study the feasibility of adapting the Super Sabre as an all-weather interceptor. The project became known as the "F-100I" (I for *Interceptor*) or "F-100BI", although these designations were not official USAF designations. This aircraft was similar in overall configuration to the F-100B except that it had a modified cockpit and was fitted with a nose radome. In order to accommodate the radome, the forward fuselage had to be redesigned so that it had an undernose variable-area air intake. Provision were made for underwing drop tanks, and the wing leading edges were to be heated to prevent icing. An all-rocket armament was to be fitted. The F-100BI was intended to bear much the the same relation to the F-100A as the F-86D did to the F-86A.
On October 20, 1953, the factory designation NA-212 was assigned to the project. Work began on wind-tunnel studies and a detailed cockpit mockup was built. Work was started on a full aircraft mockup.
In November of 1953, North American started to give some consideration to adapting the NA-212 to a fighter-bomber role. Six hardpoints were added underneath the wing, and the wing structure, controls, and cockpit were revised accordingly. Single-point refueling capability was provided and the windshield and canopy were revised to improve the pilot's view. A retractable tailskid was installed and the flight control system was upgraded by the addition of pitch and yaw dampers.
Neither the F-100B nor the F-100BI attracted all that much interest on the part of the Air Force. Consequently, on January 15, 1954, the program was cut back drastically at the request of NAA president Lee Atwood. Plans to undertake full production were abandoned, and the program was scaled back to a comprehensive engineering study.
On April 16, NAA decided to settle on the general configuration of the F-100B as being basically that of the F-100BI interceptor. However, later that month, NAA learned that the Air Force was interested in the fighter-bomber configuration of the NA-212. On May 16, 1954, North American directed that all work on the F-100B interceptor project be terminated and that all efforts now be concentrated on the fighter-bomber adaptation. The nose radome and the chin intake of the interceptor version were, however, to be retained.
In the meantime, NAA engineers had discovered that low-speed handling properties could be improved and landing speeds lowered by about 30 mph if an inboard blown flap were used for boundary layer control. These were incorporated into the design at an early stage. The F-100A had been designed without any wing flaps at all.
Among the changes needed to adapt the F-100B as a fighter-bomber was the change from a 7.33 to an 8.67 load factor, the installation of a maneuvering autopilot, the mounting of an AN/APW-11A radar beacon, a Low-Altitude Bombing System (LABS), an AN/ALF-2 chaff dispenser, an AN/APS-54 radar warning system, a plotting board and a cockpit computer. Larger and heavier wheels and brakes had to be designed, and provision had to be made for electric fuseing of external stores.
On June 11, 1954, the USAF authorized a contract for 33 F-100B fighter bombers. On July 8, 1954, the Air Force notified NAA that the designation for the project had been officially changed to F-107A, the USAF concluding that since this aircraft was so vastly different from the original F-100A it deserved a completely new fighter designation. On August 4, 1954, the contract was cut back to only nine service test aircraft under the designation YF-107A. USAF serials were to be 55-5118/5126.
Late in 1954, the Air Force issued General Operational Requirement 68, calling for a tactical fighter-bomber and an air-superiority day and night fighter. North American apparently responded to this requirement, but it is not quite sure how the F-107A fits into GOR-68. In any case, work continued on the F-107A at a feverish pace. In the meantime, Pratt & Whitney had developed the J75 turbojet, a newer and more powerful adaptation of the J57. NAA enthusiastically embraced this engine as the powerplant for the F-107A.
North American engineers redesigned the vertical tail of the F-107A fighter-bomber as a single-piece, all-moving slab. A similar innovation was adopted for the North American A3J (later A-5) Vigilante carrier-based strategic bomber. A complex spoiler-slot-deflector system on the wings provided lateral control. The wing leading edge was similar to that of the F-100A and had automatically-actuated slats, but the wing trailing edge was made up entirely of tabbed and slotted flaps. There were no ailerons, lateral control being provided by a set of spoilers above and below the wing. The aircraft had an early fly-by-wire control system known as the Augmented Longitudinal Control System (ALCS). It used air data system inputs to provide a command of pitch rate. The major offensive load was to consist of a nuclear weapon carried semi-submerged in the fuselage belly on the centerline.
Unfortunately, wind tunnel tests showed that there would be major problems with weapon release and separation caused by airflow interference from the nose radome and chin air intake. In order to correct this problem, it was decided to move the air intake from the nose to the top of the fuselage just behind the cockpit. This intake was fitted with a complex system of variable inlet ramps to adjust for optimal airflow to the engine at various speeds. A two-position (3.25 degrees and 12 degrees) engine inlet duct system was installed in the first two prototypes for the initial flight tests. This system incorporated a vertical wedge-shaped splitter in the middle of the intake, with four hydraulically-powered doors attached to the sides of the wedge inside the intake which would extend or contract as needed to adjust the intake throat area for optimal airflow to the engine. In the third prototype, the system was made fully automatic and the doors were continuously adjustable.
The main landing gear was attached to the fuselage (rather than the wing as in the F-100) and retracted forwards into bays in the fuselage. The dual-wheeled forward landing gear retracted forwards into the fuselage. There was a retractable tailskid underneath the rear fuselage to prevent damage during inadvertent high-angle landings.
The YF-107A was to be equipped with the NAA Autonetics Division XMA-12 integrated fire control system in the nose. This system was to be capable of detecting airborne targets, selecting a victim, and calculating a lead pursuit course for attack with guns or rockets.
Because of the unusual location of the air intake, it was necessary for the canopy to open straight up rather than to open in the usual clamshell fashion. In an emergency, the pilot could eject right through the canopy without having to jettison it first.
On January 1, 1957, the YF-107A contract was amended to provide for only three flying examples, plus one static test airframe.
The first F-107A (serial number 55-5118) took off on its maiden flight on September 10, 1956 at Edwards AFB, with NAA test pilot Bob Baker at the controls. It went supersonic on its first flight, although there was some minor damage upon landing when the drag chute malfunctioned and the aircraft overran the end of the concrete runway and ended up in a ditch. The aircraft was quickly repaired and flew again three days later.
55-5118 achieved its first Mach 2.0 flight on November 3, 1956.
55-5119 flew for the first time on November 28. It was equipped with the armament of four 20-mm cannon and was assigned the job of carrying out performance and integrated control system testing, and was to check out the separation characteristics of the centerline store.
55-5120 flew for the first time on December 10. It was the first YF-107 to have the fully-automatic variable area inlet duct. Unfortunately, the variable-geometry duct did not live up to its expectations. In spite of repeated attempts at steady climbs at subsonic or supersonic speeds and even zoom climbs from maximum speed at 35,000 feet, 55-5120 was never able to get above 51,000 feet. This was blamed on problems with the variable-geometry intake duct and with the J75 engine, both of which were relatively new at the time. In addition, there was an annoying "buzz" in the variable air intake at high speeds, which was traced to instability of the airflow at the inlet.
55-5118 was assigned the task of exploring the zoom climb characteristics. Test pilot Al White was able to start off at 39,000 feet at Mach 2.1, and was able to reach a maximum height of 69,000 feet.
55-5119 was assigned the job of evaluating the weapons delivery system. It was the only one of the three F-107 prototypes to be fitted with the four 20-mm M39 cannon. Wind tunnel tests had suggested that there might be problems with the release of weapons from the streamlined centerline container at supersonic speeds. After some initial problems, on February 25, 1957, test pilot Al White finally successfully delivered the weapon store while flying at Mach 1.87 over the Naval test range at China Lake.
The F-107A found itself in direct competition with the Republic F-105 Thunderchief for production orders. In March 1957, the USAF decided to go with the F-105, and the F-107 was relegated to aerodynamic testing duties. The first and third F-107As were turned over to NACA for high speed flight testing work.
The first F-107A (55-5118) reached NACA at Dryden on November 6, 1957. It was given the NACA number of 207. However, it was so mechanically unreliable that it was grounded by NACA after only four flights and was scavenged for spare parts to keep the other one flying.
The third F-107A (55-5120) reached NACA at Dryden on February 10, 1958. The flight testing of the variable geometry intake of the aircraft was cut short because of its mechanical problems. Eventually, NACA gave up on the F-107A's variable-geometry inlet altogether and it was bolted fixed in position, limiting top speed to Mach 1.2. This aircraft also experienced buffeting problems at high angles of attack. 55-5120 completed some forty test flights for NACA/NASA during 1958-59. On the basis of F-107 flight testing, North American refined the design of the side-stick planned for the X-15. 55-5120 was damaged on September 1, 1959 when test pilot Scott Crossfield was forced to abort a takeoff because of control problems. Both tires blew and the left brake burst into flames. Crossfield was uninjured, but the resulting damage to the F-107A was deemed to be too severe for economical repair, and NASA decided to scrap the aircraft. It was cut up and its fuselage shipped to Sheppard AFB in Texas where it was used for as a fire fighting training aid.
The other two F-107As still survive. After being retired by NASA, F-107A number 55-5118 was turned over to the Pima Air Museum in Tucson, Arizona, where it is now on display. F107A number 55-5119 is in the Air Force Museum at Wright-Patterson AFB in Ohio.
Serials of North American YF-107A:55-5118/5126 North American YF-107A 5121/5126 cancelled.
Engine: One Pratt & Whitney YJ75-P-9, 17,200 lbs.t. dry and 24,500 lbs.t. with afterburning. Performance: Maximum speed: 890 mph at sea level, 1295 mph at 36,000 feet. Initial climb rate: 39,900 feet per minute. Service ceiling 53,200 feet. Normal range 788 miles, maximum range 2428 miles. Dimensions: wingspan 36 feet 7 inches, length 61 feet 10 inches, height 19 feet 8 inches, wing area 376 square feet. Weights: 22,696 pounds empty, 39,755 pounds gross, 41,537 pounds maximum takeoff. Total internal fuel capacity was 1260 US gallons, carried in fuselage tanks and in two wing cells. Additional fuel could could be carried in a recessed centerline external tank, as well as in drop tanks carried underneath underwing hardpoints. Armament consisted of four 20-mm cannon M39 cannon with 200 rounds per gun (fitted only to 55-5119). A centerline position was provided for a recessed store. Six underwing pylons could be attached which could carry a total external load of 10,000 pounds.
The North American F-100C Super Sabre
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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 removable 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.
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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 refueling, a major improvement over the gravity-filling of the fuselage tanks in the F-100A. A wing-mounted detachable refueling probe was added which made the F-100C capable of in-flight refueling.
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.
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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.
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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.
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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.
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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.
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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.
F-100C-1-NA 54-1753 is on display at the USAF Museum at Wright-Patterson AFB in Ohio.
Serials of F-100C53-1709/1778 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)
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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.
The North American F-100D Super Sabre
The F-100D (company design numbers NA-223, -224, -235, and -245) was an improved version of the F-100C fighter-bomber. It was also the most widely-produced version of the Super Sabre, some 1274 examples being built.
The F-100D was intended as a dedicated fighter-bomber, with no concession being made to a secondary air-superiority role. The F-100D had a wing with an increased root chord, increasing the total wing area to 400.18 square feet. Unlike earlier Super Sabres, the F-100D was equipped with landing flaps, with the added flap area giving rise to the crank-wing trailing edge, which was the familiar distinguishing feature of the F-100D. The F-100D had the same six underwing hard points as the F-100C, but the detachable underwing pylons used forced ejection rather than gravity release for dropping their stores. The vertical fin and rudder were increased in area, and the fin trailing edge featured a larger and wider square protrusion which carried an AN/APR-26(v) rearward radar warning antenna in addition to the usual fuel jettison pipe. The nose-mounted AN/APR-25(v) gun tracking radar of the earlier F-100s was retained. The F-100D was equipped with a Minneapolis-Honeywell MB-3 automatic pilot which allowed the pilot to concentrate on navigation or tactics while the F-100D flew itself to the target. Improved electronic LABS equipment was fitted so that a MK-7, MK-38, or MK-43 nuclear bomb could be delivered. Conventional bomb loads could include six 750-pound or four 1000-pound bombs.
The first F-100D (54-2121) flew on January 24, 1956, piloted by Dan Darnell. Deliveries to the USAF began in September of 1956, the first recipient being the 405th Fighter Bomber Wing at Langley AFB in Virginia. It rapidly replaced the F-100C in most USAF wings. By the end of 1956, 79 F-100Ds were in TAC's operational inventory and 136 F-100Ds were in service at overseas bases in Japan, France, and Morocco.
There were several major deficiencies identified during early service of the F-100D. The F-100D, like the A and C before it, continued to be plagued with bugs. Among these were the unreliability of the electrical system, the incomplete tie-in between the autopilot and the low-altitude bombing system, and the inaccuracy of the MA-3 fire control system. Despite these problems, large numbers of F-100Ds entered the operational inventory before they could be corrected.
Provision for the installation of a quartet of GAR-8 (later designated AIM-9B) Sidewinder air-to-air infrared homing missiles was introduced on the production line with the 184th F-100D. Air-to-air missile armament had initially been tested on six modified F-100Cs.
Also introduced with the 184th F-100D was a provision for centerline-mounted fuselage attachment points. These points could carry "special stores"-a euphemistic term for nuclear weapons.
Nuclear weapons could be carried on the left wing intermediate attachment point or on the fuselage centerline attachment points. The nuclear weapons that could be carried included the Mk 7, Mk 28 EX, Mk 28 RE, Mk 43, TX-43, and TX-43 X1, with yields ranging from a kiloton to nearly ten megatons. For delivery of these nuclear weapons, the F-100D carried the AN/AJB-1B low-altitude bombing system (LABS). This system was used in conjunction with information provided by the A-4 gyro sight to calculate aiming and release information for the toss-bombing of nuclear weapons. In a typical mission, the F-100D would approach the target down on the deck at about 500 mph and pull up at a steady 4Gs acceleration. Partway into what would be a half loop, the bomb would be automatically released by the computer. The plane would then complete the half-loop and undergo a half-roll and head away from the target. The F-100D would then go to full afterburner in order to get as far away as possible from the bomb when it exploded.
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In late 1959, 65 F-100Ds were modified to carry the Martin GAM-83A Bullpup air-to-surface missile. The Bullpup missile was optically-guided to its target by the pilot using a radio command joystick to impart guidance commands to the missile while keeping a flare on the missile's tail lined up with the target as seen through his gunsight. The GAM-83A differed from earlier Bullpup versions in that it had an improved radio guidance system that freed the operator from the need to align the target with his sight, permitting guidance from an offset position. Delays in Bullpup deliveries caused the operational debut of the first GAM-83A-equipped F-100D squadron to slip to December of 1960. Unfortunately, this missile was to prove almost useless in Vietnam and was withdrawn from action after only a few sorties.
North American's Columbus, Ohio factory was designated as a second source for the F-100D. The first Columbus-built F-100D (company designation NA-224) with serial number 55-2734 flew on June 12, 1956.
The correction of the F-100D's autopilot problems took longer than expected. The installation of the improved autopilot, originally planned for the 184th F-100D, was delayed to the 384th. In-service F-100Ds were subsequently retrofitted with the improved autopilot.
The last 48 F-100Ds had built-in zero-length launch (ZEL) capability.
The last F-100D rolled off the production lines at Inglewood in August of 1959. Production of the F-100D at Columbus had ended in December of 1957.
Problems were encountered with the engine bearings and with the aircraft's afterburner fuel system. Problems were also encountered with inadvertent bomb releases from the underwing pylons as a result of improper bomb-loading procedures. Mid-air refuelling probes tend to fall off the wing during high-G maneuvers. This problem got so bad that for a period most refueling probes were actually taken off the F-100D aircraft, pending reinforcement of the underwing structure.
By the early 'sixties, the F-100D had been subjected to so many in-service modifications to correct its obvious deficiencies that no two F-100Ds were alike, making for a maintenance and spare parts nightmare. Beginning in 1962, about 700 F-100Ds and Fs were subjected to a series of modifications under *Project High Wire*, a major standardization and upgrading program. The goal of this program was to extend the variety of non-nuclear weapons that could be carried, to eliminate excess weight, and to standardize the cockpit and rewire it completely. Perhaps the most readily noticeable modification produced by the *High Wire* program was the addition of a spring-steel tail-hook underneath the rear fuselage. This tailhook was NOT meant for carrier-based operations, but was intended to engage wires at the end of runways to prevent overshooting during bad landings. Aircraft so modified were distinguished by adding one to their production block numbers--for example, the F-100D-25-NA became F-100D-26-NA after modification. These modifications were completed in 1965.
Even after *Project High Wire* was completed, some problems persisted. Malfunctions of the landing gear and the unreliability of the drag chutes accounted for a number of accidents. Compressor stalls of the J57-P-21 engine still occurred with high regularity. A solution to the compressor stall problems eventually was obtained by installing F-102-type afterburners on the F-100D.
The F-100D was widely used in Vietnam. Several F-100 aircraft initially stationed in the Philippines were deployed to Thailand in May of 1962 to try and restrain the Pathet Lao which were busily overrunning most of northwestern Laos. F-100s began to be stationed in South Vietnam beginning in February of 1964. The first combat strike by the F-100D was flown on June 9, 1964 when eight F-100Ds of the 615th Tactical Fighter Squadron flew strikes against targets in the Plaines des Jarres in Laos. The first recorded combat loss was an F-100D (56-3085), shot down on August 18, 1964 over Laos.
Following the Gulf of Tonkin incident, USAF F-100Ds began to fly missions over North Vietnam. These missions were generally of two types--MiG-CAP patrols to protect strike aircraft from attack by marauding North Vietnamese fighters and fighter-bomber strikes carried out with iron bombs against ground targets. On April 1, 1965, F-100Ds flew MiG combat air patrol for a strike force of F-105s that were hitting the Thanh Hoa Bridge in North Vietnam.
During these strikes, the MiGs would try to sneak up on these packages from the rear, make just one firing pass, and then flee. It was assumed that the F-100D would probably not be an effective fighter in air-to-air combat, since it lacked a powerful radar set and could not carry advanced air-to-air weapons. However, every time the MiGs tried to interfere with these strikes they immediately fled as soon as the F-100s turned toward them. Encounters between F-100s and MiGs were very few and far between, and I think that the F-100 fired its guns and missiles against enemy fighters only on one or two occasions, with inconclusive results.
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By June of 1967, only five squadrons of F-100s remained at home in the USA, most of the rest having been transferred to Vietnam to fight in the rapidly-escalating war. Although it encountered some maintenance difficulties, the F-100D proved remarkably adaptable to rough-field operations in the tropical heat and rain of Southeast Asia. For a time, F-100s enjoyed the best maintenance record of any aircraft in the Vietnam combat zone. However, as a tactical bomber, the F-100D was inferior to the F-105 and the F-4. The F-105 could carry a larger bomb load further and faster. In addition, the F-105 was built to take the extreme structural loads of low-level, high-speed flight, whereas the F-100 was not. Consequently, from mid-1965 onward, F-100D fighter bombers generally operated only in the South, leaving the North for the F-4 and the F-105. Down South, the F-100 turned out to be a very effective ground support aircraft, and beat back many enemy attacks.
Throughout the late 1960s and early 1970s, the F-100s were gradually withdrawn from combat in Vietnam and replaced by more capable types such as the F-105 and the F-4. The last F-100Ds left Vietnam in July of 1971.
The following Tactical Air Force Wings were equipped with the F-100D:
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Following their withdrawal from Vietnam, numerous USAF F-100Ds were turned over to the Air National Guard. The ANG had actually gotten its first F-100Ds in 1969, with the 174th TFS of the Iowa ANG being the first receipient. However, the needs of Vietnam had caused the USAF to delay the handover of F-100Ds to the ANG, and by mid-1970 the ANG still had only 20. As the pace of the drawdown from Vietnam stepped up, transfers to the ANG began to accelerate, and by mid-1972, the Guard had gotten 335 F-100Ds.
The F-100D served with the following ANG squadrons:
152nd Fighter Interceptor Squadron, Arizona ANG
The last F-100D was withdrawn from ANG service in 1979.
In early 1964, the Air Force Thunderbirds flight demonstration team began replacing their F-100Cs with Republic F-105 Thunderchiefs. This turned out to have been a mistake. A major F-105 flying accident in May of that year caused the USAF to decide to re-equip the Thunderbirds with eight F-100Ds modified for demonstration purposes. The USAF Thunderbirds flight demonstration team operated F-100Ds from July of 1964 until November of 1968, when they started to convert to the F-4E Phantom.
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During an air show at Laughlin AFB in Texas on October 21, 1967, Thunderbird pilot Captain Merrill A. McPeak's F-100D (55-3520) disintegrated in midair during a solo demonstration. Fortunately, he was able to eject safely. The cause was traced to a catastrophic wing failure caused by a series of wing cracks that had been produced by metal fatigue. The Thunderbirds were temporarily grounded until their planes could be fixed. Some losses in Vietnam were also thought to have been caused by this problem rather than by enemy action, and the entire F-100D fleet was temporarily restricted to a 4-G maneuver limit until all the planes could be fixed by carrying out a complete modification of the wing structural box. These modifications were not completed until 1969.
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A succession of in-service difficulties and problems beset the F-100D throughout its career. The safety record of the F-100D left a lot to be desired. Over five hundred were lost in accidents between mid-1956 and mid-1970, far more than were lost in combat in Vietnam. A lot of these accidents were due to pilot error, the F-100 being a relatively unforgiving aircraft, especially on landing. Compressor stalls were an big problem, as pilots would try to firewall the throttle too rapidly, producing a compressor stall.
F-100D 56-3440 is in storage at the Paul E. Garber Facility of the Smithsonian Institution in Suitland, Maryland.
An F-100D in Thunderbirds markings is on display at the USAF Museum at Wright-Patterson AFB in Ohio. I am unaware of the serial number of this particular aircraft.
Serials of the F-100D:54-2121/2132 North American F-100D-1-NA Super Sabre (NA-223) 54-2133/2151 North American F-100D-5-NA Super Sabre (NA-223) 54-2152/2221 North American F-100D-10-NA Super Sabre (NA-223) 54-2222/2303 North American F-100D-15-NA Super Sabre (NA-223) 55-2734/2743 North American F-100D-35-NH Super Sabre (NA-224) 55-2744/2783 North American F-100D-40-NH Super Sabre (NA-224) 55-2784/2863 North American F-100D-45-NH Super Sabre (NA-224) 55-2864/2908 North American F-100D-50-NH Super Sabre (NA-224) 55-2909/2954 North American F-100D-45-NH Super Sabre (NA-224) 55-3502/3601 North American F-100D-20-NA Super Sabre (NA-223) 55-3602/3701 North American F-100D-25-NA Super Sabre (NA-223) 55-3702/3814 North American F-100D-30-NA Super Sabre (NA-223) 56-2903/2962 North American F-100D-60-NA Super Sabre (NA-235) 56-2953/3022 North American F-100D-65-NA Super Sabre (NA-235) 56-3023/3142 North American F-100D-70-NA Super Sabre (NA-235) 56-3143/3198 North American F-100D-75-NA Super Sabre (NA-235) 56-3199/3346 North American F-100D-90-NA Super Sabre (NA-235) 56-3351/3378 North American F-100D-80-NH Super Sabre (NA-245) 56-3379/3463 North American F-100D-85-NH Super Sabre (NA-245)
Engine: One Pratt & Whitney J57-P-21/21A turbojet, 10,200 lb.st. dry and 16,000 lb.st. with afterburning. Dimensions: Wingspan 38 feet 9 inches, length 50 feet 0 inches, height 16 feet 2 3/4 inches, wing area 400 square feet. Performance: Maximum speed 770 mph at sea level (clean), 864 mph (Mach 1.3) at 36,000 feet (clean). Initial climb rate 19,000 feet/minute. An altitude of 35,000 feet could be attained in 2.3 minutes. Service ceiling 36,100 feet, combat ceiling 47,700 feet, absolute ceiling 50,000 feet. Normal range 534 miles, maximum range 1995 miles. Fuel capacity 1739 US gallons internally, total of 2139 gallons if maximum external fuel is carried. Weights: 21,000 pounds empty, 28,847 pounds gross, 34,832 pounds maximum takeoff. Armament: Four 20-mm Pontaic M-39 cannon. Six underwing pylons for up to 7040 pounds of bombs, fuel tanks, or rockets. A MK-28 or Mk-43/57/61 nuclear weapon could be carried. In later versions, four AIM-9B/E/J Sidewinder air-to-air infrared homing missiles could be carried.
The North American F-100E Super Sabre
For some obscure reason, the designation F-100E was never assigned.
The North American F-100F Super Sabre
The F-100F two-seat Super Sabre originated on May 10, 1954 in a North American design study for a supersonic trainer version of the F-100 single-seat day fighter. The initial in-service accident rate of the Super Sabre had been alarmingly high, and it was suspected that part of the problem might be the inexperience of its pilots. It was thought that a two-seat trainer version might help green pilots get used to this hot new supersonic aircraft. On September 2, 1954, the USAF offered to loan NAA a standard F-100C for conversion to trainer configuration under the designation TF-100C.
In December of 1955, a contract was issued for 259 TF-100Cs, the contract being accompanied by a corresponding reduction in F-100D procurement.
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The USAF loaned F-100C 54-1966 to North American for the conversion to two-seat configuration, and the converted TF-100C flew for the first time on August 3, 1956, NAA test pilot Alvin S. White being at the controls. The company designation was NA-230. The TF-100C lacked all operational equipment. On April 9, 1957, the TF-100C was lost when it spun into the ground and crashed during a spinning test. Fortunately, test pilot Bob Baker ejected safely.
In the meantime, the two-seat Super Sabre concept had evolved into a combat trainer under the company designation of NA-243. The USAF designation was changed to F-100F. Full combat capability was to be retained and the same underwing loads as the F-100D were to be carried. However, the internal armament was reduced to two 20-mm cannon rather than the four guns of the F-100D. The front cockpit contained all the controls for the armament.
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The first production F-100F (56-3725) was flown on March 7, 1957, NAA test pilot Gage Mace being at the controls.
First deliveries of the F-100F began to the USAF in January of 1958, and by the end of that year, F-100Fs had reached most of the overseas units that were operating F-100Ds.
The F-100F-20-NA (company designation NA-255) was a special production model developed at the specific request of the Pacific Air Forces. It was equipped with a navigational system including an AN/ASN-7 dead-reckoning computer, a PC-212 Doppler radar, and a standard J-4 compass system. It had modified flaps with a span-wide duct built into the leading edges to direct air from the lower surface over the upper to reduce buffeting during landing. The flaps had a full deflection angle of 40 degrees, as compared to the 45-degree angle of deflection for the standard F-100D and F.
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The last of 339 F-100Fs was delivered in October of 1959. All of them were built at NAA's Los Angeles plant. Included in this total were 45 aircraft specifically purchased for the Military Assistance Program and intended for export to US allies overseas. Total Super Sabre production finally totaled 2294, including 359 built at Columbus.
In 1959, fifteen F-100Fs were modified to carry the GAM-83A Bullpup air-to-surface guided missile.
The same engine malfunction problems, wing structural failures, spare and parts shortages, and component deficiencies that bedeviled the F-100D were also experienced by the F-100F, which is not all that surprising since they were basically the same airframe. In 1962, all F-100Fs (along with their F-100D single-seat cousins) began to go through *Project High Wire*, which was an extended program to standardize the weapons delivery system which had been modified on so many separate occasions that individual aircraft ended up with significant differences from each other, making for a maintenance and spare parts nightmare.
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When American bombing raids against North Vietnam began in 1964, combat losses of US aircraft began to mount. Many of these losses were caused by the increasingly effective use by the North Vietnamese of radar-guided surface-to-air missiles. Someone in the USAF got the bright idea that the best way to defeat the surface-to-air missile threat was to destroy or otherwise shut down their guidance radars, leaving enemy missile sites effectively blind and impotent.
In 1965, several F-100Fs were modified for the role of identifying, marking, and attacking North Vietnamese SAM sites, particularly their radar installations. Applied Technology Inc. did much of the early work. This company began by adapting electronic equipment that had originally been developed for the U-2. In the system which eventually emerged, the F-100F was provided with an AN/APR-25 radar homing and warning receiver which was capable of detecting the S-band signal emitted by the North Vietnamese SA-2 fire control radar as well as the C-band signal emitted by upgraded SA-2 systems and the X-band signals emitted by enemy airborne interception radars and radar-guided antiaircraft artillery. A cockpit display included a "threat panel" plus a cathode-ray tube which showed the bearing of the threat signal. An AN/APR-26 receiver was fitted which detected missile guidance launch signals by sensing a power change in the enemy's command guidance radar signal and flashed a red launch warning signal light in the cockpit. An IR-133 receiver was fitted, this receiver having a greater sensitivity than the APR-25 homing and warning receiver and having the additional capability of indicating the nature of the threat by signal analysis.
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The modified F-100Fs carried the usual load of 20-mm cannon ammunition plus a pair of LAU-3 canisters loaded with 24 rockets which served as markers as well as weapons which could demolish a radar site. Fighter-bombers accompanying the F-100F would then attack the target with iron bombs. The project was given the name *Wild Weasel*, after the fierce little mammal which has a reputation of being so fearless that it pursues its prey into its very den.
Wild Weasel F-100Fs included 58-1221, 1226, 1227, 1231, 1212, and 1232. The first F-100F Wild Weasel I aircraft arrived in Southeast Asia in November of 1965. The first Wild Weasel F-100F combat mission was flown on December 3. The missions were flown under the codename *Iron Hand*, and the antiradar missions were usually flown by one F-100F accompanied by four F-105s. The F-100F would identify and mark the radar site for attack by the accompanying F-105Ds.
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Three additional Wild Weasel I aircraft arrived in SEA on February 27, 1966, also to participate in the *Iron Hand* anti-SAM campaign. Later, F-100Fs carried AGM-45A Shrike anti-radiation missiles. The Shrike missile contained a passive homing system which detected the enemy radar beam and followed it all the way back to its source. The first combat use of the Shrike was on April 18, 1966, when F-100Fs themselves began attacking North Vietnamese radar sites.
On August 11, 1967, Lt.Col. James E. McInerney Jr and Capt. Fred Shannon in an F-100F led a mission that destroyed six SAM sites and damaged four, clearing the way for a strike on Hanoi's Paul Doumer Bridge.
The F-100F Wild Weasel I program claimed credit for nine confirmed SAM radar kills. An undetermined number of other enemy radars were forced off the air as a result of Wild Weasel I activities. Two F-100F Wild Weasel I aircraft were lost in action.
Having proven the general concept, the F-100F Wild Weasel I was eventually replaced by the F-105F Wild Weasel III and the F-4 Wild Weasel IV
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F-100Fs also flew as forward air controller (FAC) aircraft, replacing lighter planes such as the Cessna O-2 Bird Dog in this role. This switch was made after enemy antiaircraft made it too hazardous for light planes to operate, especially in areas where there were SAMS, AAA, or the threat of MiGs. The crew member in the rear seat had the maps, carried a hand-held strike camera, and communicated by radio with the fighters in the strike team. When the strike team arrived at the target, the pilot would fire the markers and the rear seat would direct the strike. These high-speed FAC missions were flown under the codename *Misty*.
As F-105s and F-4s became available in quantity, F-100Fs were phased out of the active Air Force inventory and passed along to the Air National Guard. The Air National Guard had received an initial batch of six F-100F in 1958, but acquired very few more until the late 1960s because of the needs of the Vietnam war. As the 'sixties came to an end, the pace at which F-100F left Air Force service quickened and large numbers of F-100Fs began to reach the Guard. By June of 1972, almost all F-100Fs were out of USAF service, and a hundred F-100Fs were in service with the ANG.
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Even though the F-100F had originally been designed as an operational trainer intended to familiarize pilots with supersonic flight, its safety record was just as atrocious as that of its single-seat F-100D version. About a quarter of all F-100Fs built were destroyed in accidents. This leads one to suspect that it wasn't just a problem with pilot training that was the cause of the Super Sabre's high accident rate, but basic problems with the aircraft itself.
The first F-100F (56-3725) was modified by the USAF Systems Command's Aeronautical Systems Division for testing of very steep approaches and very fast landing speeds. This work was done in preparation for the X-15 and Dyna-Soar programs. In order to perform these tests, means had to be found to build in a large additional drag which could be added or removed on command. This was done by replacing the drag chute and afterburner by a thrust reverser that could be operated in flight. In addition, the standard belly airbrake was replaced by a special perforated air brake with almost three times the area. The use of these features enabled the F-100F to touch down at 230 mph rather than the usual 155 mph.
Serials of the F-100F:56-3725/3739 North American F-100F-1-NA Super Sabre (NA-243) 56-3740/3769 North American F-100F-5-NA Super Sabre (NA-243) 56-3770/3919 North American F-100F-10-NA Super Sabre (NA-243) 56-3920/4019 North American F-100F-15-NA Super Sabre (NA-243) 58-1205/1233 North American F-100F-20-NA Super Sabre (NA-255) 58-6975/6983 North American F-100F-15-NA Super Sabre (NA-261) - for MDAP 59-2558/2563 North American F-100F-15-NA Super Sabre (NA-262) - for MDAP
Specifications of the F-100F:
Engine: One Pratt & Whitney J57-P-21/21A turbojet, 10,200 lb.st. dry and 16,000 lb.st. with afterburning. Dimensions: Wingspan 38 feet 9 inches, length 50 feet 0 inches, height 16 feet 2 3/4 inches, wing area 400 square feet. Performance: Maximum speed 760 mph at sea level, 852 mph at 35,000 feet. Initial climb rate 23,800 feet/minute. Service ceiling 44,900 feet, combat ceiling 51,000 feet. Normal range 358 miles, maximum range 1294 miles. Fuel capacity 1294 US gallons. Weights: 21,712 pounds empty, 31,413 pounds combat, 39,122 pounds maximum takeoff. Internal armament consisted of two 20-mm Pontaic M-39 cannon. Underwing loads could include up to 5000 pounds of bombs and fuel tanks on six stations.
The F-100F Super Sabre With Foreign Air Forces
The Super Sabre served with four foreign air forces, those of France, Denmark, Turkey, and Nationalist China.
The QF-100 Drone
Numerous outdated F-100Ds were modified as pilot-less drones to give Air Force pilots and Army ground-to-air missile crews experience against realistic targets. These aircraft were re-designated QF-100.
In August of 1979, a contract was awarded to Sperry Flight Systems for the conversion of 9 QF-100 drones. Two were YQF-100 development aircraft with added cockpit controls so that they could be flown by pilots for system evaluation. Three were built to standard USAF target configuration, three were built to Army requirements, and one was a two-seat version. The eight F-100Ds converted to QF-100 configuration had the serial numbers 55-3610, 55-3669, 56-2912, 56-2978, 56-2979, 56-3048, 56-3324, and 56-3414. The single F-100F had the serial number of 56-3984.
Following these tests, a total of 209 QF-100 conversions were made by Tracor/Flight Systems Division from F-100s that had been preserved at the Davis-Monthan AFB in Arizona. These conversions were painted bright red-orange and had a few extra blade antennas for the transmission and reception of radio signals from the remote-controllers on the ground. The last QF-100 conversion took place in April of 1985.
The takeoff of the QF-100 drone was directed by two ground-based controllers positioned at the end of the runway. Once airborne, the drone was handed off to a third controller sitting in a fixed-base ground station. A dual redundant system was used to get the drone to the mission area and to select the maneuvers. The maneuvers were pre-programmed into on-board computers. If the drone survived the mission, it was flown back to the handover point, where the two controllers at the end of the runway brought it back in for a landing.
The first unpiloted flight of a QF-100 took place on November 19, 1981 from Tyndall AFB in Florida. Recently, the QF-100 has been used as a target in the AMRAAM (Advanced Medium-Range Air-to-Air Missile) program. The first AMRAAM kill against a QF-100 took place on September 17, 1985. The lifetime of a typical drone was about ten flights before it was destroyed.
The ZEL F-100
In the mid-1950s, NATO officials became concerned with the possibility that Soviet nuclear weapons could obliterate Allied aircraft sitting on the ground at their airfields in a surprise attack, leaving NATO powerless to retaliate. One of the potential cures for this problem was to disperse aircraft in hardened shelters far away from targeted airfields, and having these aircraft launched by rocket propulsion from special platforms. The concept was known as Zero-Length Launch, or ZEL for short.
A contract change made on October 12, 1956 stipulated that NAA would build the last 148 F-100D aircraft with ZEL capability. Two F-100Ds (56-2904 and 56-2947) were loaned by the USAF to NAA for tests of the ZEL system.
In order to launch the F-100D, NAA's Rocketdyne division developed a solid-fuel rocket motor that would be attached to the bottom of the rear fuselage. This engine was capable of delivering a thrust of 130,000 pounds for four seconds. This was sufficient to accelerate the F-100D from zero to 300 mph in four seconds. Following burnout, the rocket motor would drop off the aircraft, leaving the Super Sabre free to fly.
The first five launches took place with dummy airplane-shaped masses attached to the rocket motor. The first such launch took place on December 12, 1957.
The first live launch of an F-100D took place on March 26, 1958. On that day, test pilot Al Blackburn climbed into 56-2904, started the engine, pushed the throttle to full afterburner, then lit the rocket motor. Within four seconds, he was flying at 300 mph. The rocket booster dropped off, and Blackburn entered the standard pattern and landed safely.
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On his second flight, things did not go so well. After burnout, the rocket motor would not drop off the aircraft and Blackburn was forced to eject. However, the remaining of the total of 20 launches were incident-free. Airplanes taking place in test launches carried standard underwing stores, including dummy nuclear weapons.
Although the system was reliable and relatively simple to operate, it was never deployed operationally.
The Unbuilt F-100s
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The production history of the Super Sabre came to an end when the last F-100F two-seater was delivered. However, there were several other Super Sabre variants subsequent to the F-100F which were the subject of serious design studies but which never saw the light of day.
For some odd reason, the designation F-100G and F-100H were never assigned.
The F-100J (probably J for Japan) was the designation given to a projected, but unbuilt all-weather interceptor version offered to Japan through the Foreign Military Sales program. The Japanese government expressed no interest, and the project proceeded no further than the concept stage.
F-100K was to have been a version of the two-seat F-100F in which the J57-P-21A was replaced by the J57-P-55. This version was never built.
F-100L was to have been the designation of an equivalent J57-P-55-powered version of the single-seat F-100D. This version was never built either.
The designation F-100M was never assigned.
The F-100N (probably N for NATO) was to have been a "stripped" version of the F-100D with simplified electronics that would be offered to the air forces of NATO nations. It attracted little interest and was not proceeded with.
The designations F-100P,Q, and R were never assigned.
The F-100S (probably S for Spey) was a 1964 proposal for a F-100F airframe powered by a Rolls-Royce RB.168-25R Spey turbofan. North American had hoped to establish a production line in France for two hundred examples of the F-100S, but nothing ever came of the idea, and no F-100S was ever built.
- North American F-100 Super Sabre, David A. Anderton, Osprey, 1987
- The North American F-100 Super Sabre, Ray Wagner, Aircraft in Profile, 1965.
- The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston, Orion, 1988.
- United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
- The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.
- Fighters of the United States Air Force, Robert F. Dorr and David Donald, Temple Press Aerospace, 1990.
- American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.
- Post-World War II Fighters, 1945-1973, Marcelle Size Knaack, Office of Air Force History, 1986.
- E-mail from Jack Daub, who flew MiG CAPs in Vietnam.
- E-mail from Larry on F-100 experiences.
Curtsey of JOE BAUGER
The First Production Jet Fighter To Go Supersonic In Horizontal Flight
The world's first supersonic fighter interceptor belonged to the same family as the famous F-86 Sabre. In February, 1949, Ray Rice and Ed Schmued undertook design studies for a developed version of the F-86 which was to have a 45-degree angle of sweep on the wings and use a new Pratt & Whitney jet engine which could develop three times the thrust of the Sabre's engine: the aim was to build a fighter which could exceed the speed of sound even in level flight.
The "Sabre 45" was offered to the USAF as a supersonic all-weather fighter but the military requested North American to concentrate on a daytime interceptor role. On November 1, 1951, the USAF ordered two prototypes of the new aircraft from the company, designating them YF- 100. In 1952, this designation was changed to YF-100A to reflect the numerous modifications which had been made to the original design.
On May 25, 1953, George Welch took off from Edwards Base, where the Air Force Flight Test Center was located, in the YF-100A and broke the sound barrier during this maiden flight. The Super Sabre, as the plane came to be known, was a cantilever low-wing monoplane, with 45 degree sweep-back, powered by a two-stage Pratt & Whitney J57-P-7 with afterburner, the oval air intake being horizontally positioned in the nose. The wings were equipped with leading-edge slats and hydraulically operated slatted ailerons on the trailing edge. The tailplanes also had 45-degree sweepback and were fully powered, located very low on the rear end of the fuselage. The engine and afterburner were installed in the rear fuselage and the pressurized and air conditioned cockpit was fitted with an ejector seat; the canopy was of clamshell design, faired into the tailplane by means of a dorsal spine.
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On the F-100A, the underside of the fuselage was an airbrake and the container for the brake-chute. In the front strut of the tricycle landing gear had double truck and retracted into the fuselage while the side struts retracted into the wings. In the F-100 program it was the first time that a very large proportion of titanium was used in aircraft construction, invaluable for its strength and lightness and this sent construction costs soaring. Backed by the first prototype's success, the new plane went into full production, and the first F-100A flew as early as October 29, 1953, only a matter of days after the second prototype had started flight testing on October 14. That same day the commanding officer of the Air Force Flight Test Center, Lt. Col. Frank K. Everest, known to his friends as "Speedy Pete" broke the world speed record in the first YF-100A, reaching 755.149mph at Salton Sea. Two years later, on August 20, 1955, an F-100C managed to do even better, at 822.135mph.
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But all was not well... a series of accidents had started to worry designers and those responsible in the USAF for overseeing the program; when the first test pilot of the Super Sabre, George Welch was killed while testing the plane to the limits of its structural strength, all F-100As which had already been delivered to 479th Group were grounded. A month went by before it was discovered that the tailplane fin was not large enough or strong enough for control of the plane under certain flight conditions. The aircraft currently in production had their fin and rudder surface area increased by 27 percent and all aircraft which had already been delivered were similarly modified, solving the problem.
In February, 1955, the F-100As were cleared and put back into service, by which time production of this series had ended, with a total of 203 built, and the assembly lines switched to the series C, ground attack variant. A total of 476 of these F-100C fighter-bombers left the assembly lines, with a redesigned strengthened "Wet Wing," so called because of the fuel no longer being contained inside special tanks in the wing but free-flowing inside the wing structure, increasing capacity. Hardpoints for bombs and missiles had been increased to six.
The next variant, the F-100D, was also a fighter-bomber and 1,274 were built.. these had larger vertical tail planes and flaps on the trailing edge of the wing; an autopilot system was installed, as was a rearward-looking warning radar and the LABS (Low Altitude Bombing System); these series aircraft also had in-flight refueling capability. The F-100D was equipped to carry and launch nuclear warheads.
The last F-100 version, the F series, was based on a prototype which had originally been designated TF-100C, a stretched fuselage two-seat trainer which was fully equipped for combat missions but with reduced armament, having two 20mm cannons instead of the four standard in other variants. A total of 339 F-100Fs were built and the entire Super Sabre production run ended when the last of these left the assembly lines in October 1959.
The B variant of the F-100 never went into production under this designation; an all-weather model, it was much faster and more powerful than the basic variant and was eventually redesigned and produced as the F- 107. The F- 100D and some F- 100F aircraft were used to carry out important research into the possibility of assisted take-off or, more accurately "rocket launching" these aircraft from mobile launching pads, such as an especially built launching truck.
On May 18, 1958, an F-100A took off in a ZEL (Zero Length Launch) experiment, with no runway at all, propelled into the air by its own engine in afterburner, boosted by a 130,0001b thrust Astrodyne rocket. The takeoff was, in fact, a lift-off. The purpose of these experiments was to explore the possibilities of aircraft being able to take off from places far away from conventional airfields, since the latter would probably be among the first places to be destroyed by the enemy in case of war.
After approximately five years' front line service the F- 100s were gradually replaced by the F-105 or by Phantoms and they were relegated to use by 19 Squadrons of the Air National Guard which used them until 1980.
From 1956, F-100C planes were chosen by two very demanding users, the USAF aerobatic teams, the "Thunderbirds" in the States and the "Skyblazers" in Europe, both of these display teams flying them for many years at hundreds of air shows. The F-100 first saw action when they were already becoming obsolescent: during the Gulf of Tonkin crisis in 1966, when four Super Sabre Wings were recalled into service and sent to Vietnam where they continued to serve until 1971, during which time these (relatively few) planes flew more combat missions than the total flown by 16,000 Mustangs during World War 11. Third Tactical Fighter Bomber Wing
Turkish Air Force F-100F alone completed more than 100,000 missions before the end of l969. When assigned to close support duties or used as ECM platforms these Super Sabres proved excellent warplanes and many a pilot, when converting to different, more up-to-date airplanes, regretted parting with his old " Hun " (from " Hundred "). Although the F- 100 may have been assigned the number by coincidence, the Super Sabre was the plane selected to inaugurate the "Century Series" of fighters and this, the USAF's first supersonic plane was a worthy choice. Other users of the F-100 purchased their aircraft under the Mutual Assistance program implemented in 1959, under which USAF planes which were "surplus to requirements" were ceded to friendly countries.
As already noted, the F-100 had the reputation of being a dangerous plane at one point: 95 accidents for 100,000 flying hours, even though few of these involved fatalities. Today, however, the record shows that the average total of flying hours clocked up by each F- 100 is a very impressive 5, 100 and this must have earned the plane a better reputation. The Super Sabre was an extremely advanced plane in its day and merits respect for its influence on later combat planes. President Eisenhower echoed the whole aeronautical fraternity's admiration for the Super Sabre when he honored North American's president, J. H. Kindelberger, and his design team with the Collier Trophy on December 17, 1954, in recognition of their services to the aviation world.
North American F-100D/F Super Sabre:
The F-100Ds, last single-seater version of the first American supersonic fighter, provided with an autopilot and also armed with bombs attached to the underside of the wings, played an important role in the Vietnam war, with over 300,000 missions from August 1964 to July 1971. The Super Sabres, familiarly known as 'Huns,' a shortened version of 'Hundred', were immediately used for low-level night bombing missions, and during the first years of the war pounded objectives in South Vietnam where suspected concentrations of Viet Cong had been sighted. For this type of mission the F-100Ds were armed with two CBU-24 bombs which, on opening, released a large number of anti-personnel devices, and two 750lb napalm bombs.
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Once they had dropped their load, the Super Sabres proceeded to spray the zone under attack with their four 20mm cannons to complete the cleaning up work. Because of their adaptability and, even more, the lack of a real alternative, numerous F-100 Wings were used in Vietnam, some of them consisting of squadrons of the Air National Guard, called up for front line service. The 3rd TFW alone carried out more than 100,000 missions in 1969! From the end of 1965 a number of two-seater F-100Fs, the Wild Weasel 1, carrying anti-SAM electronic equipment, were in action, operating from the Korat base in Thailand.
F-100 PHOTO GALLERY
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