F-97A / F-94C Starfire
The next stage of improving the Starfire was the modification, formerly known as the F-97A and Lockheed L-188, later renamed the F-94C. New feature included, Pratt & Whitney J48-P-5 or -5A engine (8,300-1b thrust with afterburner; 6,250-1b, without); thinner wings, with increased dihedral; sweptback horizontal stabilizer; aft dive flaps, drag chute; and longer nose with radome in retractable shield. Allrocket armament accommodated 48 2.75-inch folding-fin aerial rockets 24 in a ring of firing tubes around the nose and 24 in two cylindrical pods. One pod was located on each of the two wings, midway between root and tip. Alsb featured were wing and horizontal stabilizer thermal de-icing, single-point refueling, greater fuel capacity, as well as the Hughes E-5 fire-control system and Westinghouse W-3A autopilot (for, instrument approach).
The prototype flight took place 11 months before the Yk'-9413's first official flight. Converted F-94A.s were used in each case. The entire F-94 program finally totalled 862 productions--109 F-94As (against a fret order for 160), 856 F-84Bs, and 387 F-94Cs (originally known as F-97As). Air Force records, however, showed only 2 prototypes (1 YF-94B and 1 YF-94C) officially accepted-others were accounted for as production aircraft, or charged to another program (as were the P-94A prototypes, developed from F-80C and T-33 productions).
The USAF decision for a redesigned F-94 (referred to as the F 97A) followed reappraisal of the F-94 program and January 1950 plans calling for haste in supplying the air defense forces with better and more of the Lockheed interim interceptors. The Air Force realized a drastically improved P-94A was not there for the asking. It then settled for a third, but "in-between type," that preceded the so-called F-97A-the F-94B, which still fell short of the Air Force's early 1960 expectations.
The F -97A, endorsed by the Air Force in February 1950, formally became the F-94C--third, biggest, and last of the F-94 model series as well as the final upshot of the basic Shooting Star design.
The F-94C ran immediately into trouble. To begin with, the first production deliveries were scheduled for 1951--far too early. Both the Pratt & Whitney J-48 engine and laminar wings specifically earmarked for the F-94C, were not likely to be fully developed when needed. Other improvements or new components (many also intended for the F-94B) were slipping. The automatic approach system was not ready; testing of the 250-kilowatt-radar, rocketnose, and collision-course sight was not due until 1951; development of an advanced fuel purging system showed scant progress, and the only autopilot available was too big even for the larger F-94C.
Although this plane was not accepted by the Air Force until May 1952, it did not go directly to the operational forces.
The Air Force allocated to the testing program the F -94C proto type (first flown as the YF-97A in January 1950 and accepted in October), together with 9 other aircraft received by the end of June 1962. None of these "test productions" performed well. ADC concluded that low speed (some 40 knots less than the F-89) and poor maneuverability downgraded the F-94C. Nevertheless, it would be acceptable if these deficiencies were corrected. Some of them-the unsatisfactory fuel system in particular-were reported by test pilots of the Air. Research and Development Center (ARDC) as resulting from poor design and substandard quality control during production. Others reflected a variety of causes that combined to erode the plane's efficiency.
On its first trial in August 1951, the F-94C's J48-P-5 engine had passed its 150-hour qualification test, but its afterburner had warped and cracked. After much testing and redesign, the engine finally passed new qualification tests in May 1952 with afterburner intact. Fuel burner nozzle failures occurred soon afterward. Since it was impossible to find defective nozzles by visual inspection, the F-94Cs were grounded. Fitting all engines with improved nozzles solved the problem before the end of 1952. Despite fairly good engine performance after some modifications, the Air Force in mid-1962 still sought to enhance the rate of climb and high-altitude reliability of the P-5. It considered switching to the higher thrust J48-P8, but installation difficulties wiped out the project.
A joint study (Headquarters USAF, Air Proving Ground Command (APGC), ARDC, and ADC) called for variable position dive brakes, aileron spoilers, a better drag chute, and further improve ment of the engine reliability. The study also recommended speedy installation of the aircraft's new rocket armament (early F 94Cs still carried machineguns) and additional rockets.
By mid-October 1952, the F-94C's flight characteristics and con trols were improved. More than $3.5 million had been allotted to modify the cockpits of early F-94Cs (Some 260 F-94Cs would probably feature the F-94A and F-94B small cockpits and the Air Force did not expect $3.5 million to fill the bill. ), and work was underway to correct the aircraft's inadequate de-icing boots and faulty stall warnings. Lockheed had also arranged for field installation of the variable position dive brakes and aileron spoilers. Drag chute improvements were progressing and ways to upgrade the engine's reliability were under review. Armament difficulties, however, remained unsolved.
The success of the F-94C's all-rocket armament hinged on rocket accuracy and interceptor performance reliability. .The F-94C and its rockets had neither. The F-94C's all-rocket armament had been a key selling point. Admittedly, a salvo of rockets would cause more damage than a burst of machinegun fire. Worse, the P-5 engine flamed out when the full-nose load of 24 rockets was salvoed above 26,000 feet. If only 12 rockets were fired, a near flameout still occurred that slowed the interceptor speed. The Air force wanted the problems cured and the rocket load doubled. Both could be done. In fact, the mounting of additional rockets in wing pods had been considered since 1951. Nonetheless, it was unlikely the F -94C would get its extra rockets before the 163d production.
Improvements notwithstanding, two of the four production con tracts (the first, definitized on 27 July 1950, dealt with the F-97A) were cancelled late in the year, cutting F-94C procurement from 617 to 387. The Air Force considered cancelling the entire program in July. It held off because of anything better and the need (in the midst of the Korean War) to keep Lockheed in production.
In the spring (beginning with the 100th production-not the 163d), F-94Cs came off the assembly line with wing pod "side arms:' Each pod packed 12 of the Aeromite-developed FFARs. The long cylinder pods measured 9 feet 6 inches and their fiber glass nose covers protruded about 6 feet from the wing leading edge. Before the rockets left the pods, the fiberglass covers disintegrated due to rocket-generated gas pressure. The produc tion-improved F-94Cs also came with new ejection seats that would lift both the pilot and radar observer well above the cockpit sill.
With ADC's 437th FIS at Otis AFB. As the first rocket-bearing interceptor, the F-94C generated less enthusiasm than expected. Maintenace crews praised the F-94C, because they could get to its electronics equipment easily. Pilots generally liked the aircraft, commenting that the J48P-6 engine "wheezed, coughed, spurted, and blurped at altitude; but it never quit running." Nearly 2 years behind schedule, it showed limited performance. And, clearly, its basic design could not be stretched further to meet future needs. Intended as a "quick-fix" all-weather interceptor to fill the air defense gap until the F-89 was ready, 1949 planning had envisioned an operational F-94C in 1951. Moreover, the F-94C (like the F-94A and B) could not destroy any bomber superior to the Russian TU-4 that compared with the B-29.
The 437th FIS attained initial operational capability in June.
In mid-1954, squadron operational suitability tests confirmed the F-94C's poor weather-proofing and disclosed leaky fuel tanks. They also revealed the need to improve the E-5 fire-control system. During continuing rain in late 1863, 80 percent of the alert aircraft at one base went out of commission. Moisture in the cockpit had short-cixgluited the electrical and fire-control systems.
Known as Hop-Up, these modifications resolved the F 94C's recently confirmed shortcomings. Early F-94Cs also exchanged their ejection seats for the safer ones featured by later produc tions. The Hop-Up modification of the E-5 eventually added an optical sight to the system.
The Air Force took delivery of 9 F-94Cs in FY 52, 153 in FY 53, and 225 in FY 54. The YF-94C had been accepted in October 1951. Cost per aircraft was: $534,073.00-airframe, $380,755; engine (installed), $90;147; electronics, $7,058; ordnance, $518; armament, $55;595.
F-94D: A single-seat fighter-bomber for long-range ground sup port. The D would have a high-thrust centrifugal flow turbojet engine with afterburner, plus autopilot and airborne equipment to allow automatic approach and tactical control from the ground. Authorized for procurement in mid-1951 (when the Korean War started), one F -94D prototype was developed (through conversion of an early F-94 production), but the 112 F-94Ds on order were all cancelled.
Despite mediocre performance, the F-94C lasted a long time as a first-line interceptor. The Air Force wanted to get rid of the aircraft, but could ill afford it. The P-94C in mid-1954 (when ADC counted a peak 265) was still regarded as the best two-man interceptor at low altitudes. Despite many structural modifications, the F-89 operated. poorly, particularly at low level; and the Convair F-102 (originally due to enter service in mid-1963) was several years away. As for the development of a low-altitude surfaceto-air missile (investigated under Project LASAM), this was out of the question insofar as the Air Force was concerned. It planned instead to test low-altitude seekers that ADC could possibly use on its future Bombers. At one time during 1955, 48 percent of the Air Force's remaining F-94Cs were grounded for lack of parts. The F-94C finally. disappeared from USAF rolls in early 1959; from the ANG's in mid
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