F-102 "Delta Dagger"
The Air Force designated Convair interim interceptor the F-102A. The production delayed, ultimate MX-1554, while retaining its original designation, would acquire a subsequent model letter series and become the F-102B. In 1956, after numerous engineering changes had further widened the two interceptors' dissimilarities, the Air Force redesignated the F-102B as the F-106.
A number of design changes were requested. The Air Force decided the F-102A should be capable of carrying external stores (fuel tanks, armament, and the like). Also, cockpit components of the MX-1179 ECS (simultaneously inspected with the F-102A) had to be rearranged.
The Air Force, Convair, and Hughes agreed to equip the F-102A with an interim fire control system, since it had become certain service test quantities of the MX-1179 ECS would not be available prior to October 1955. Huges E-9, a modified E-4, was selected. The MX-1179 ECS and the MX-1554 airframe had been specifically designed to complement each other, and the MX-1179's temporary deletion from the F-102A proved to be an important decision. In effect, it marked the defeat of the weapon system concept's first application, for the MX-1179 never reached the F-102A. The E-9 (renamed MG-3 after a number of technical changes had substantially increased its overall capability) was eventually replaced by the MG-10. This system (itself a former MGR incorporating the AN/ARR-44 data link, the MG-1 automatic flight control system, and the AN/ARC-34 miniaturized communication set) became a permanent feature of the F-102A. Meanwhile, by almost imperceptible steps, the interim F-102A took on greater importance, and the quantities discussed grew larger. More emphasis on the F-102A meant less on the ultimate interceptor, leading to an insidious program change. The realities of the development situation, however, dictated this undesirable trend.
The F-102A's development problems first centered on its weight, which was increasing continuously. The Westinghouse J-40 (the most powerful US turbojet engine qualifed for production in early 1961) lacked the thrust to give the F-102A the minimum requisite speed and altitude. Its replacement, the Pratt and Whitney J-57P-11, officially rated as being in the 10,000 lb class and due to enter production in February 1953, was heavier. The post mockup inspection requirements for additional armament also generated extra weight, as did the aircraft's new fire control system, heavier than the future MX-1179. Meanwhile, a much more serious problem loomed.
NACA wind tunnel tests in early 1953 showed that the maximum altitude of 57,000 feet and combat radius of 350 miles (304.3 nm) predicted for the F-102A were too optimistic. The designers of the original Convair proposal (MX-1554) had failed to make proper allowance for a delta wing aircraft's aero-dynamic drag. The area rule concept of aircraft design (that interference drag at transonic speed depends almost entirely on the distribution of the aircraft's total crosssectional area along the direction of flight) was verified during December 1962 by Richard T. Whitcomb in NACA's new transonic wind tunnels.
Convair drag estimates of the F-102A in its bulky amidship configuration did not coincide with the data upon which they were based. The solution was to indent the fuselage to a "coke-bottle" or "wasp waist" configuration, but first the contractor had to be convinced that its original design was in error. However, it was not until mid-1953 that Convair accepted the implications of the "NACA ideal body theory" and joined in the recommendations that the F-102A's design conform to this theory's requirements.
The LCs, previously awarded to Convair, were superseded by a definitive contract. This contract, still based on the Cook Craigie production plan, did not affect the number of aircraft initially ordered. Out of the 42 aircraft under procurement, several were earmarked for testing and two (F-102A prototypes) were scheduled for flight in October and December 1953, respectively. Production dates were significantly changed, however. Limited production would not begin until April 1954--10 months later than programmed in December 1951. Accelerated production of a combat ready, fully tested weapon system was planned for December 1955--almost 2 years later than first anticipated.
The first YF-102A, flown from Edwards AFB in October 1953, crashed on 2 November, but not before the aircraft's anticipated poor performance was fully demonstrated. The flight tests, resumed several months later with the second YF-102A (first flown on 11 January 1954), could only confirm that the F-102A in its present configuration was drag limited to Mach .98 with a 48,000 ft ceiling considerably below the required. The F-86D, that the F-102A was supposed to supplant, had a service ceiling of 49,600 feet and a maximum speed of 601.7 kn (Mach .9). It was fully operational in mid 1968, the initial production date originally set for the F-102A.
While the MX-1179 deletion from the F-102A defeated the weapon system concept's first application, the aircraft's unavoidable redesign made havoc of the Cook Craigie plan for early tooling. Of the 30,000 tools already purchased by Convair in October 1953 (when testing established unequivocally that important changes had to be made in the plane's design), 20,000 had to be discarded and new ones bought, a sizeable increase in production costs. Meanwhile, the April 1954 wind tunnel and scale model tests of a remodeled F-102A (that included cambered leading edges, reflex wing tips, rearward relocation of wing, relocation of vertical fin, 7 ft fuselage extension, and redesign of fuselage to incorporate the principles of the area rule "coke-bottle" configuration) reflected continuing deficiency in performance. Moreover; airframe and component changes had added 3,500 pounds to the aircraft's weight.
In May 1954 the Air Force approved further redesign of the first "coke bottle" configuration. The new drag reducing changes extended the fuselage another four feet and added: a new canopy (lighter and providing better visibility), new engine intake ducts, an aft fuselage fairing, and wing camber modifications. The J-57P-23 engine (generating 16,000 pounds of thrust, or approximately 1,200 pounds more thrust than the 11) was to replace the 11 and the interim -41 (an 11 engine modified for new air bleed probes to eliminate cabin fumes). A major weight reduction, likewise, was initiated.
Redesign of the F-102A, once agreed upon, was accompanied by new production decisions. The Air Force in March 1954 gave Convair a second production contract calling for delivery of 37 additional F-102As between February and July 1955. A third and larger order, placed in June 1954, scheduled the delivery of another 108 aircraft between August and December 1956.
Convair's new production contracts were soon followed by definite qualifications. In November 1964 the Air Force issued a set of general operational requirements that called for altitude performances up to 54,000 feet, a combat radius of 326 nautical miles, and speeds up to Mach 1.23 at 35,000 feet. The Air Force also placed an informal (but nevertheless meaningful) hold order on the FY 1956 funds for the 108 F-102As, recently ordered. This hold order would prevail until forthcoming flight tests of the new F-102A proved to be satisfactory.
A "synthetically modified" production F-102A made its initial flight and demonstrated substantial performance improvement over the original configuration, reaching Mach 1.22 and an altitude of 53,000 feet. This demonstration "coke bottle" prototype (nick named the Hot Rod to distinguish it from the two earlier YF-102As and the few initial straight fuselage productions allocated to the testing program) was fitted with fillets designed to the latest, light weight configuration that had been approved by the Air Force in May 1954. It was powered by an advanced production of the improved J-57-P-23 turbojet, due for delivery in June 1955.
Evaluation of the Hot Rod prototype's preliminary flight tests led the Air Force to rescind in early 1955 its administrative hold order of the previous year. Ensuing flight tests by Air Force pilots, while demonstrating that the aircraft's stability needed improving, were also satisfactory. They ended in June 1955, after the aircraft's initial high speed had been equaled and its original altitude performance actually exceeded. Ten months of structural integrity testing were initiated in July, when the Air Force concluded (after numerous airborne firing tests) that the F-102A would be able to launch the Falcon missile, as well as 2.75 and 2 inch rockets. A high point in the series of armament tests was reached on 8 July, when the YF-102A fired 6 Falcons and 24 rockets in less than 10 seconds.
The first "Production Aircraft" flew on 24 June 1955. This was the first production F-102A built to the Hot Rod, lightweight, "coke bottle" configuration. The aircraft was accepted by the Air Force on 29 June, 5 days after its first flight.
The F-102A first entered service with the Air Defense Command's 327th FIS at George AFB. It became the Air Force's first delta-wing aircraft almost 3 years past the June 1963 production date in the LC of December 1951, some 7 months beyond the revised delivery schedule of 1954, and nearly 10 years after the experimental, delta wing F-92's first flight.
One month before the F-102A entered operational service, the Air Force and Convair decided to give the F-102A a larger fin. This new design change, endorsed after a period of extensive testing, would alleviate the aircraft's instability, a remaining problem particularly acute at high speeds. The change became effective with the 26th F-102A, after Convair production schedule had been adjusted for this purpose. Enlarged fins were retrofitted on the 25 aircraft already off the production lines.
As once planned and in order to simplify logistical support of the F-102A, the Air Force decided in mid 1956 that (beginning with all post-December productions) only the 2.75 inch Folding Fin Aerial Rocket would be used as backup to the Falcon (GAR-1 and infrared -1B) guided missiles the aircraft's primary armament. Operational F-102As and those released from production before the decision could be implemented, would exchange their T-214 2-inch FFARs for the standard 2.75 inch rockets. Necessary modifications were subsequently made in the field by teams from the Air Force San Antonio Air Materiel Area, Tex. Some 170 F-102s were modified. In the meantime, after the first air-firing of an MB-1 rocket was accomplished from a YF-102 in May 1956, the Air Force again considered equipping the F-102A with Genie rockets, even though this would entail another production delay. This project, however, was given up in early 1957.
The Air Force gave Convair a fifth and final contract for 140 F-102As in September 1956, 10 months after the fourth and largest (562 aircraft) F-102A production contract had been placed.
One year after becoming operational, the F-102A still harbored a number of deficiencies, but most defects were being corrected. By November, all F-102As had been retrofitted with serviceable struts and the incorporation of a new oleo strut metering pin and revision of the side brace boss bearing of the landing gear in all future F-102A productions gave assurance that the long standing problem of landing gear failure (susceptible of affecting also the more advanced F-106 interceptor) was finally solved. Convair in addition had devised a fix for speed brake failures in flight, another critical problem which had dictated the reinspection of speed brake in each F-102A.
While the F 102A's operational problems were being corrected, efforts to further improve the aircraft's performance did not slacken. After a successful prototype flight in May 1957, F-102As acquired a new wing. Referred to as the Case XX wing and phased into production after October 1967 (beginning approximately with the 550th F-102A), this final major structural change raised combat ceiling to 55,000 feet (a 5,000 ft increase), boosted maximum speed at 50,000 feet to Mach 1 (a Mach 0.06 gain), and, substantially improved maneuverability. The F-102A's stability at low speeds, still marginal despite the previous in-production incorporation of a larger fin, also improved vastly.
Modernization of the F-102A, undertaken almost concurrently with the aircraft's final production change, lasted several years from 1957-1963. The F-102A was still being modernized long after some of the aircraft had already begun to leave the regular forces. This took care of the air defense needs, increasingly provided by the Air National Guard, and of important oversea requirements.
First involved were the addition of data links (Data links furnished the pilot information electronically rather than by voice.) and replacement of the MG-3 fire control system by the improved MG-10. There followed the substitution of more sophisticated and less trouble some GAR missiles (as they became available) and the addition of the nuclear Falcon Model Y52A. This atomic missile, first known as the GAR-11 and subsequently redesignated the AIM-26A, had been designed by Hughes specifically for the F-102A. In 1963, after more than 450 aircraft had been modified and provided the necessary kits (one kit per aircraft, at an initial cost of $10,000 per kit), half of the F-102 interceptors (trainers included) could carry the AIM-26A. Ensuing modifications eventually provided interchangeable utilization of AIM-26 and AIM-4 (GAR 1 through 4 series of Falcons in post 1962 nomenclature) missiles in the center missile bay of a number of F-102As. Under project Big Eight (and still as part of the F-102A modernization), incorporation of an Infrared Search and Track System into the F-102 fleet also began in 1963.
The F-102As were first deployed oversea in June 1958, when ADC's 327th FIS the Air Force's first F-102A unit moved to Thule, Greenland. The F-102As reached Europe and Alaska early in 1960, after some of the aircraft (due for deployment to oversea bases which only had tactical air navigation ground stations) were engineered to provide for the installation of AN/ARN 21 airborne TACAN equipment. The F-102As also joined the Pacific Air Forces early in 1960. They were to remain in both the European and Pacific theaters for nearly 10 years.
Four F-102s were sent from Clark AB, P. I., to South Vietnam in March 1962, after radars had detected low flying, unidentified aircraft along the Cambodian border. This started a series of rotations every 6 weeks by Navy EA-1F all weather fighters and USAF F-102s to Tan Son Nhut. The rotation ended in May 1963 due to base overcrowding. Nonetheless, from the summer of 1963 to mid 1964, Thirteenth Air Force conducted no-notice deployments of F-102s to South Vietnam and brief training flights to Tan Son Nhut and Da Nang. The small number of aircraft committed to SEA air defense before 1965 tripled by the end of 1966. At that time 12 F-102s stood alert in South Vietnam (6 at Bien Hoa and 6 at Da Nang) and another 10 in Thailand (6 at Udorn and 4 at Don Muang). Little change occurred in 1967 and 1968, the Air Force keeping a minimum of 14 F-102s on 5 minute alert with the remainder of the force on 1 hour call. F-102 operations in SEA ended in December 1969 (The last F-102 squadron at Clark was inactivated. However, a few F-102s remained at the Royal Thai Air Base of Don Muang until the summer of 1970.) with a remarkable safety record. In almost 10 years of flying air defense and a few combat air patrols for SAC B-52s, just 15 F-102s were lost.
The F-102A's overall safety record (including all SEA losses) was also impressive. In more than 14 years of operation, only 16 percent of the F-102A total force, or less than 140 aircraft were lost in flying accidents. A minimal number of ground accidents occurred, bringing total F-102A operational losses to 141 as of 30 June 1971.
There were no subsequent model series. The TF-102 (trainer variant of the F-102A) entered production almost concurrently with the Hot Rod, light weight, F-102A.
There were no other configurations besides the TF-102A. The F-102C, an F-102A that would use an advanced engine (the J-57-P-47 with titanium compressor), never came into being. The Convair F-102C proposal of 1956, then referred to as the F-102X, also included a tail cone extension of 7 inches and an armament load of one MB-1 Genie rocket and four Falcon missiles. The contractor expected that these changes (estimated to result in a speed increase to Mach 1.33 and a 3,000 ft altitude gain over existing F-102As) would qualify the new model to fill a possible gap between the end of the service life of the F-102A and the introduction of the F-106. The Air Force in April 1957 decided to refuse the Convair proposal and to rely rather on the F-106 being ready for tactical inventory starting in mid 1958. Throughout the years the Air Force used a number of F-102As for special tests. As required by the testing programs in which they were used, these aircraft were sometimes stripped of their original components or fitted with additional equipment. They appeared on Air Force rolls on and off as JF-102As, but this was only a temporary designation. The Air Force used the J prefix to identify every tactical aircraft diverted to special test programs and later returned to their original or standard operational configuration.
Production ended in September 1958 with delivery of the last five aircraft. Of 889 F-102As accepted, 875 were assigned to the operational inventory and 14 were set aside for the testing program (2 YF-102As, 8 other early straight fuselage aircraft, and 4 F-102As, built to the first major redesign configuration without intention of modification to a tactical configuration).
One F-102A was accepted for the operational forces in FY 55, 45 in FY 56, 372 in FY 57, 427 in FY 58, and 30 in the first 3 months of FY 59. The highest production delivery was made in June 1956, when the Air Force accepted 51 aircraft. The Air Force accepted five straight fuselage F-102As (including two prototypes) in FY 54 and five more in FY 55. The four redesigned, nontactical F-102As were accepted in FY 55.
RDT&E costs totalled $101.92 million--prorated, it came to $101,921 and was included in every F-102's unit cost.
The Flyaway Cost Per Production Aircraft was $1.2 million airframe, $744,258; engine (installed), $210,308; electronics, $9,208; armament, $219,876; ordnance, $525. This excluded $137,947 in prorated Class V modification coats and $11,612 spent on each F-102A for specific modifications.
The Average Cost Per Flying Hour was $611.00
Phaseout occured from 1961-1973. The F-102A replaced the F-46D as the most numerous interceptor and by the end of 1958 they numbered 627, or about half the total number of interceptors controlled by ADC. The F-102A began to leave the air defense system with the receipt of the F-101B and F-106A, but in mid 1961 there were still 221 of these aircraft available within ADC. Toward the end of 1969, when except for one squadron maintained in Iceland, all F-102s of the Air Defense Command had been transferred to the Air National Guard, the Air Force still retained a few oversea F-102 squadrons. Two were in the Pacific theater, three in Germany and one in the Netherlands. However, the F-102 squadrons stationed in Europe were being reequipped with newer, more versatile F-4s and the F-102A's Pacific commitments were coming to an end. In mid 1972, only 17 F-102s (15 F-102As and 2 TF-102As) remained in the operational inventory of the Air Force and 69 F-102s were surplus. By 30 June 1973 the number of active USAF F-102s had been reduced to 10. Meanwhile, the F-102A had become an important asset of the Air National Guard. After receiving in 1960 an initial contingent of seven F-102As, the ANG's operational inventory of F-102As grew quickly. It jumped to 130 F-102s in 1961 and in mid 1966 reached 339 (311 F-102As and 28 TF-102As), a total that remained fairly constant in the ensuing years. In mid 1972, the ANG operational inventory of F-102s was down to 206 (181 F-102As and 25 TF-102As), but a USAF allocation of surplus F-102s had boosted this total to 224 by 30 June 1973.
The Air Force decided to convert aging F-102s into target drones. They would be used in Pave Deuce, an Eglin AFB program calling for low cost, full size, supersonic targets, representative of enemy aircraft (MIG-21s) in aerial combat. The Sperry Rand Corporation was selected for the conversion over Lear Siegler, Northrop, Celesco Industries, Lockheed Aircraft and Hughes Aircraft teamed with Honeywell. The $5.5 million Air Force contract awarded in April 1973 called for the modification of six F-102s into two different drone configurations. Two aircraft would be converted into QF-102A versions, retaining pilot controls for use in contractor operated flights. The remaining four would be turned into "deman-rated" afterburning targets, designated PQM-102As. The Pave Deuce PQM-102As would only be flown as drones, using less costly "de-man-rated" parts and checkout procedures. Sperry Flight Systems Divisions, Phoenix, Ariz., would handle the conversion, to be completed within 16 months. Ultimately, as many as 200 surplus F-102s might be modified.
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