The Convair F-102 "Delta Dagger"

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 The primary mission of the F-102 was to intercept and destroy enemy aircraft. It was the world's first supersonic all-weather jet interceptor and the USAF's first operational delta-wing aircraft. The F-102 made its initial flight on Oct. 24, 1953 and became operational with the Air Defense Command in 1956. At the peak of deployment in the late 1950's, F-102s equipped more than 25 ADC squadrons. Convair built 1,000 F-102s, 875 of which were F-102As. The USAF also bought 111 TF-102s as combat trainers with side-by-side seating.

In a wartime situation, after electronic equipment on board the F-102 had located the enemy aircraft, the F-102's radar would guide it into position for attack. At the proper moment, the electronic fire control system would automatically fire the F-102's air-to-air rockets and missiles.

Type Number built/Converted Remarks
Remarks YF-102
YF-102
F-102A
TF-102A
F-102B
10
4
875
111
0
Prototype YF-102A
Area rule Interceptor
Dual-cockpit trainer
Became F-106

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The first  four F-102's arriving at Castle AFB for The 456th FIS   1958    

Courtesy of Donald Baker

SPECIFICATIONS
Span: 38 ft. 1 in.
Length: 68 ft. 4 in. (including boom)
Height: 21 ft. 2 in.
Weight: 31,559 lbs. max.
Armament: 24 unguided 2.75 inch rockets and six guided missiles
Engine: One Pratt & Whitney J57 of 16,000 lbs. thrust with afterburner
Cost: $1,184,000

PERFORMANCE
Maximum speed: 810 mph.
Cruising speed: 600 mph.
Range: 1,000 miles
Service Ceiling: 55,000 ft.

Courtesy of The Air Force Museum

Hughes AIM-4D Falcon

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The missiles mounted inside the weapons bays of this F-102 are Hughes AIM-4D "Falcons," guided by an infrared (heat-seeking) homing system. In 1955, the AIM-4 Falcon became the USAF's first operational air-to-air guided weapon. Additional armament consists of 24 2.75-inch folding fin unguided "Mighty Mouse" rockets, two in each of 12 tubes located inside the weapons bay doors. These rockets are partially visible at the forward ends of the doors.

The weapons bays on both sides open evenly together; to show both the open and closed configurations on display, only the right side is fully open to firing position.

 

HUGHES AIM-26B Falcon Air-to-Air Missile

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AIM-26B

The AIM-26 Falcon was the only guided nuclear-armed air-to-air missile ever deployed by the USAF. Development of a nuclear-armed derivative of the AIM-4 Falcon family was first planned in 1956, when Hughes was contracted to develop the XGAR-5 and XGAR-6 missiles. These missiles were intended to be significantly larger than the standard Falcon (length/diameter increased from 2.0 m/0.16 m (80 in/6.4 in) to about 3.5 m/0.30 m (140 in/12 in)), and were to be used against high and fast-flying missiles and bombers. The two variants were identical, except for the guidance method - semi-active radar homing for the XGAR-5, and infrared homing for the XGAR-6. However, development was cancelled early in the design phase.

GAR-11 (AIM-26A) GAR-11A (AIM-26B)

Development of a nuclear-armed Falcon derivative started again in 1959, when it was decided that USAF interceptors needed a head-on kill capability against enemy bombers. This dictated radar homing (IR seekers of the day could only home on hot exhaust), but this was considered too inaccurate for a conventionally armed missile. Therefore a low-yield W-54 nuclear warhead was planned for the missile, which was designated as GAR-11.

The GAR-11 was slightly larger, and significantly heavier than the original Falcon. Testing of the XGAR-11 proceded without problems during 1960, and in 1961, the GAR-11 became operational with F-102 interceptors. The nuclear warhead, and the inherent all-weather capability of the SARH guidance made the GAR-11 the most powerful air-to-air missile ever deployed. Detonation of the warhead was triggered by a radar proximity fuze.

However, the nuclear warhead also had a major disadvantage - the missile could not be used against low-flying aircraft over friendly territory. Therefore the conventionally armed GAR-11A was developed in parallel. The GAR-11A was relatively little used by the USAF, but was exported to Sweden (and license-built there) as RB-27.

In 1963, the GAR-11 Falcon missiles were redesignated in the AIM-26 series. The XGAR-11, GAR-11, and GAR-11A became the XAIM-26A, AIM-26A, and AIM-26B, respectively.

Improvements in radar-homing in the late 1960's made the AIM-7 Sparrow missile effective in frontal attacks. This fact, together with the AIM-26A's unsuitability against low-level threats, led to a quick phase-out, and by 1971 the AIM-26A was no longer in service. The Swedish RB-27 (AIM-26B) was used by J 35 Draken fighters until the late 1990's. In total, about 4000 AIM-26 missiles of both variants were produced.

Specifications

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

Data for GAR-11 (AIM-26A):

Length 2.14 m (84.2 in)
Wingspan 0.620 m (24.4 in)
Diameter 0.279 m (11 in)
Weight 92 kg (203 lb)
Speed Mach 2
Range 8-16 km (5-10 miles)
Propulsion Thiokol M60 solid-fuel rocket; 26 kN (5800 lb)
Warhead W-54 nuclear fission warhead (0.25 kT *)

* The 250 T yield is the figure quoted by most public sources. However, according to a first-hand account of an individual who worked with the weapon, the true nominal yield was actually 1.5 kT.

Main Sources

[1] James N. Gibson: "Nuclear Weapons of the United States", Schiffer Publishing Ltd, 1996
[2] Bill Gunston: "The Illustrated Encyclopedia of Rockets and Missiles", Salamander Books Ltd, 1979

 

F/TF102A Weapons System.

By  Dennis W. Reiling, Fire Control Systems Tech

 

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A mock_up of the MC-10 Fire Control System

The F102 Fighter Interceptor was equipped with the MG-10 Fire Control  weapons system manufactured by the Hughes Aircraft Company.  The aircraft was capable of searching out targets and attacking with radar or infrared guided AIM 4D Falcon air-to-air missiles or 2.75 rockets.  The radar system would scan the target area.  The pilot selected and locked on to a target.  His radar search display was then replaced by an attack display.  The system utilized an analog computer, which provided steering information to the pilot on the attack run, handled the missile set up and fired the selected (by the pilot) weapons.  The pilot had to have the firing trigger pulled to allow the system to automatically fire. The armament was stowed in the belly of the airframe. The bay doors contained twelve tandem rocket tubes, which were exposed when the doors opened.   The doors also exposed three missile bays.  Each bay had one forward and one rear missile launching rail.  In a salvo-firing event the rear rails would fire first.  While they were retracting the forward missiles would be coming down to firing position.  High air pressure bottles right behind the cockpit powered the doors and rails. 

For the times the system was complex. It was composed of mechanical relays, electronic vacuum tubes, servos, and motor driven gear trains with cams. It was powered by a motor-generator, which supplied all voltages except for the aircraft’s primary 28vdc and 115v 400 cycle.  The MG-10 system had a Built In Test  (BIT) used by the ground crew for maintenance of the system.  The ground crew also had a Dynamic Accuracy Test Set (DATS cart) test set.  This was connected to the aircraft by central cables and the Radom was covered with a Radar absorbing blanket.  The test set would generate a target, which the ground crew could lock onto and watch the system perform the attack run. This test set was used as a periodic calibration not routine maintenance.   This could include the actual bay doors and launcher operations. This was not usually performed, as the system’s operation of the doors and rails was violent.

The airborne weapons evaluation was routinely performed in a debriefing situation.  This was assisted by a recorded tape of the radarscope attack display and exposed Polaroid film from the missile simulators loaded on the rails. The missile parameters were presented in a binary number pattern.  This information was evaluated to determine performance and success of the mock attack.

The MG-10 Weapons System was modified and improved to the MG-13 that was employed on the F101 Voodoo Fighter Interceptor.

By; Dennis W. Reiling, Fire Control Systems Tech  with The 456 FIS             12/12/02

Thank You Dennis!

Other Than The Above I Have  Been Unable To Locate Any Additional Information On The F-102, Weapons system Or Aramment.2

 

Area Rule and how the F-102 broke the Sound Barrier

 

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The concept known as the area rule is one of the great success stories of airplane design. The area rule says very simply that the transonic wave drag of an aircraft is essentially the same as the wave drag of an equivalent body of revolution having the same cross-sectional area distribution as the aircraft. This fact, coupled with the knowledge of the shape that minimizes drag shows designers how to reshape the fuselage and other components of an airplane to reduce the drag of the total configuration.

Since the rule was formulated, and verified experimentally, attempts have been made to estimate aircraft wave drag by a theoretical analysis of the equivalent-body area distributions. It has been found that reasonably good wave drag estimates can be made near a Mach Number of 1 if the slender-body-theory is applied to the aircraft area distribution. Numerous theoretical and experimental investigations have shown that the fuselage and other components of an airplane can be reshaped in a way that will reduce the wave drag of the total configuration. A typical configuration will frequently have a fuselage with a local minimum of area near the middle of its length, sometimes referred to as "coke-bottling".

The transonic area rule was considered so valuable that attempts were quickly made to extend the results to higher Mach numbers. This theoretical effort culminated in the development of the so-called Supersonic Area Rule, which is more complicated than the transonic rule.

This procedure can be extended to higher Mach numbers with good accuracy by using the supersonic area rule to determine the equivalent-body area distributions. The area distribution for the transonic area rule can be developed with drafting techniques. The supersonic area rule depends on computing areas intercepted by oblique cuts through a configurations and requires a considerable amount of computational geometry.

While Whitcomb was conceiving and testing his area rule concept, the Convair Division of General Dynamics was developing what it hoped would be the company's first supersonic aircraft. The Convair F102 "Delta Dagger" was designed to be a long-range interceptor, with delta wings and the most powerful turbojet engine available at that time, the Pratt & Whitney J-57. Early test results of an F-102 model in Langley's 8-Foot High-Speed Tunnel, however, seemed to indicate that the design's transonic drag might be too high for the aircraft to surpass Mach One.

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The NACA had immediately classified any information pertaining to the area rule, as it had the research on the slotted throat wind tunnel that allowed the area rule to be developed. In 1952, the United States was engaged in heated and high-stakes competition for military superiority with the Soviet Union, and NACA realized the importance of transonic research in developing superior military aircraft. Although the classification was necessary, it made dissemination of information about the area rule more difficult. Fortunately, NACA's history of successful technology transfer efforts had been less a product of published writings than the various levels of informal NACA-industry cooperation and researcher-to-engineer discussions.32 The area rule would prove no exception.

In mid-August 1952, a group of Convair engineers were at Langley to observe the performance of the F102 model in the Eight-Foot High-Speed Tunnel. Shown the disappointing test results, the engineers asked the Langley engineers if they had any suggestions. Whitcomb's first research memorandum on the area rule would not be published for another month, but he had completed his tests on the various wing-body combinations using indented fuselage shapes. He explained his findings and the area rule concept to the Convair team.

Intrigued, the Convair engineers worked with Whitcomb over the next few months to experiment with modifying the F-102 design and building a model that incorporated the area rule concept. At the same time, however, the company continued work on the original F-102 prototype. The engineers may have been open to exploring a possible new option, given the uncertainty produced by the wind tunnel tests of the original F-102 model, but the company had already made a commitment to the Air Force to build two prototypes of the original F-102. In addition to any mental and institutional resistance Convair might have had to changing a design which it had touted so highly and had already made a commitment to build, the company's commitment also created an issue of cost.

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By mid-1952, when Convair tested the F-102 model at Langley, the company had already begun setting up a production line at its San Diego, California, facility for manufacturing the aircraft. To change the design would mean not only delays and additional engineering costs, but revamping the production line, as well. Consequently, far from being receptive to a new design approach, Convair had a significant stake in proving that its new aircraft could perform just fine without it. 33

Nevertheless, the company could not totally ignore the doubtful test results of its original design, so its engineers began working on a "Plan B" with Whitcomb while production of the prototype F-102s continued. Starting in May 1953, the Convair engineers and Whitcomb began testing models of a modified, area rule-based, F-102 design in Langley's wind tunnel. By October 1953, they had developed a model that could meet the Air Force performance specifications. Convair noted the results but continued working on the original F-102 prototype, which flew for the first time on October 24, 1953. 34 The first prototype was severely damaged on its maiden flight, so test flights had to be postponed until January 11, 1954, when the second prototype flew for the first time. The results of the flight tests, however, proved to be largely the same as those predicted by the wind tunnel tests of the F-102 model in 1952. The aircraft performed below expectations and could not attain supersonic speeds in level flight. 35

Even at that point, Convair might have continued to press for production of the design as it was, given that the tooling and production line in its San Diego plant was already set, except for one crucial factor. The Air Force officials working on the F-102 design were aware of Whitcomb's area rule and the fact that a modified F-102 model, based on that concept, had achieved supersonic speeds in wind tunnel tests. Consequently, the Air Force realized that the F-102 was not the best that Convair could do. Whitcomb's experiments had proven that a supersonic airplane was possible, and the Air Force decided to settle for no less. The F-102 program manager at Wright Field in Ohio informed Convair that if the company did not modify the F-102 to achieve supersonic flight, the contract for the fighter/interceptor would be cancelled. 36

Incorporating Whitcomb's innovative design approach involved extra expense, but nothing compared to the cost of losing the entire F-102 contract. Convair immediately halted the F-102 production line and began working on the modified design Whitcomb and the company engineers had developed and tested. In only 117 working days, the company had built a new, area rule-based prototype, designated the F-102A. The F-102A flew for the first time on December 24, 1954, and surpassed the speed of sound not only in level flight, but while it was still in its initial climb. The area rule had improved the speed of the F-102 design by an estimated twenty-five percent. 37

While Convair was struggling with its F-102 design, the Grumman Aircraft Engineering Corporation was also working to develop its first supersonic carrier-based fighter, the F9F/F-11F Tiger.38 Although the area rule research was classified, the NACA released a confidential Research Memorandum on the subject to appropriately cleared aircraft manufacturers in September 1952. Just two weeks after receiving that memorandum, Grumman sent a group of its engineers to Langley to learn more about it. The information they brought back to Bethpage, New York, was immediately incorporated into the design, and in February 1953, Whitcomb was flown in to review the final design plans before construction on the prototype was begun. On April 27, 1953, the Navy signed a letter of intent with Grumman for the fighter, based on the Whitcomb-approved design. On August 16, 1954, the Grumman F9F-9 Tiger "breezed" through the sound barrier in level flight without the use of the afterburner on its Wright J-65 turbojet engine.39

The enthusiastic incorporation of Whitcomb's innovation by Grumman stands in stark contrast to the qualified experimentation and resistance that characterized Convair's response. But the two companies were in different situations. Convair had already completed a design for the F-102 and had begun construction of two prototypes and a production line. Grumman, on the other hand, was still working to design the F11F Tiger when Langley published its confidential report on Whitcomb's area rule breakthrough. It was the perfect time to incorporate a better design idea, and involved few extra costs to the company. At the same time, the Navy had not yet contracted for the fighter, and Grumman may well have recognized that its chances of winning the contract would be improved by incorporating any available new technology into its design; especially something that might improve its speed.

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In any event, Whitcomb's innovative idea was incorporated into two production military aircraft only twenty-four months after he completed his initial wind tunnel tests on the concept. This incredibly "successful" example of technology transfer was a result of two important factors. First and foremost, there was a "problem looking for a solution" 40 that the area rule was able to solve. Transonic drag was a real and seemingly insurmountable obstacle to supersonic flight. Whitcomb's area rule was not one of a number of potential solutions; it was the only approach anyone had developed that had proven itself capable of overcoming that barrier. It also had the backing of a very powerful customer: the United States military. When the Air Force decided to hold firm on its demand that Convair's aircraft fly supersonically in level flight, Convair could not simply sell its F-102s to another customer. The Air Force was its only client, just as the Navy was for Grumman.

But another important element, especially with regard to Convair, was the cooperation and individual relationships that existed between the Langley researchers, including Whitcomb, and the industry engineers. The modified F-102A model that proved to the Air Force that a fighter could achieve supersonic flight was a cooperative effort between Whitcomb and Convair engineers. Without that cooperation, or the informal discussions at Langley that launched that work, the fate of the F-102 might have been different.

The area rule undoubtedly would have been incorporated into aircraft designs eventually, regardless of the individuals involved. But that timeframe could have been different, which could have had an impact on the kind of air defenses the United States had at its disposal in the early days of the Cold War.

As it was, the success of the area rule-based F-102 and F11F was followed by the incorporation of the area rule in virtually every supersonic aircraft built after that point. The Vought F8U "Crusader" fighter and the Convair B-58 "Hustler" bomber, both of which were on the drawing board at the time the area rule was developed, were redesigned using Whitcomb's approach. The F-106, which was Convair's follow-on design to the F-102A, adhered even more to the area rule. It was able to incorporate a much deeper indentation in the fuselage than its predecessor, because it was an entirely new aircraft, unencumbered by existing design elements.

The fuselage of the Republic F-105 "Thunderchief" fighter/bomber, which flew for the first time in 1955, incorporated the area rule in a slightly different manner. It could not be indented because of its complex engine inlets, so a bulge was added to the aft region of the fuselage to reduce the severity of the change in the cross sectional area at the trailing edge of the wing. The Rockwell B-1 bomber and the Boeing 747 commercial airliner also used the addition of a cross-sectional area to reduce their drag at transonic speeds. Both the B-1 and the 747 have a vertical "bump" in the forward section of the fuselage ahead of the wing. It is perhaps more visible in the 747, where it houses the airliner's characteristic second story, but both airframe modifications were added to smooth the curve of the design's cross-sectional area. 41

The Collier Trophy

 

The Collier Trophy

Whitcomb's Area Rule research was classified until September 1955, so he did not receive any immediate accolades or press on his discovery. But two months after his work was made public, Whitcomb received the National Aeronautic Association's Robert J. Collier Trophy in recognition of his achievement the previous year, when the Grumman F9F-9 Tiger and the Convair F-102A prototypes demonstrated just how significant the area rule was. The Collier Trophy citation read, "For discovery and experimental verification of the area rule, a contribution to base knowledge yielding significantly higher airplane speed and greater range with the same power. " 42

 

 

 

 

Conclusion

 

Although an engineering design approach using formulas or algorithms does not lend itself to the kind of notoriety that a project like the X-1 generated, the development of the area rule was no less significant. The X-1 proved the sound barrier could be broken. The area rule made that discovery practical by enabling production aircraft to operate at that speed.

The fact that the area rule was discovered by an engineer sitting with his feet up on his desk, contemplating a vision in his mind, also shows the importance of creativity and the individual in advancing technology. Postwar science and research projects may have been growing in complexity and size, but Whitcomb's discovery was a reminder that the

41. Whitcomb, interview, May 2, 1995; Whitcomb, "Research on Methods for Reducing the Aerodynamic Drag at Transonic Speeds," November 14, 1994, p. 3.

42. Bill Robie, For the Greatest Achievement: A History of the Aero Club of America and the National Aeronautic Association, (Washington, DC: Smithsonian Institution Press, 1993), p. 232; Richard T. Whitcomb, telephone interview with author, May 15, 1995.

 

1      A Brief History Of The F-102 2      The FY-102A
3      The F-102A 4     The TF-102A
5      The F-102 In Vietnam 6      Flying The F-102
7      President Bush And The F-102 8

     Bush and I

9      The Area Rule 10  
11 12