INTERAVIA, November 1970|
The following article was first published in November 1970 in the aviation magazine INTERAVIA, pp. 1384 - 1387. Today, this article is - as I see it - a somewhat historic document. Remarkable in this article - from todays point of view - is the presence of the Cold War and Soviet threat which strongly influences the argumentations.
The first Grumman F-14A twin-engine, variable geometry, carrier-based jet fighter designed for the US Navy to provide air superiority and fleet air defence is expected to make its first flight sometime next month. Before the design and production programme leading up to this event is examined in detail, a summary of what the Chief of Naval Operations and Navy Department expect of this new aircraft will help clarify for the reader the role for which it has been developed.
The F-14 will fill the fleet air defence need for which the F-111B was designed, and it will replace the F-4 as an air superiority fighter in escort roles. The F-14 provides its two-man crew of pilot and missile control officer with a one-piece canopy and tandem seating for maximum, clear vision, unswept wing carrier landings at 120 knots, and highly manoeuvrable fighter performance at 68 degrees full wing sweep.
The F-14 was conceived as a low risk development programme to provide improved air-to-air capabilities in the earliest possible timeframe. The F-14A will be equipped with improved versions of the existing AWG-9/Phoenix missile control system and Pratt & Whitney TF-30-P-412 engines. This version will become operational in April 1973 to meet US fleet air defence needs.
An advanced technology engine (ATE), the Pratt & Whitney F401-PW-400, under development in a joint US Navy/Air Force programme, will have 40 per cent more thrust, weigh 25 per cent less than the TF-30-P-412, and be incorporated in the F-14B version for operational use in December 1973, providing manoeuvrability and weapon system performance to counter any threat expected during the 1970s.
The US Navy's requirement fir the F-14 stems from the fact that its stable of fighters is rapidly becoming obsolete. The current Navy fighter inventory includes the F-8 Crusader and the F-4 Phantom, both of whose design originated more than 15 years ago. Sea-based tactical air power has been an invaluable instrument of US policy over the years. The F-14 is seen as required to replace the F-4 in air superiority and escort roles in the mid-1970s, because the projected threat which will confront the US at that time already includes four new Soviet fighter aircraft, each of which has better performance than the F-4J. The abandonment of the F-111B set the Navy behind in its schedule to acquire an air superiority fighter replacement. While the F-4 in Southeast Asia has had a 1:1 kill ratio against older MiG-21 versions since August 1967, the F-4J almost certainly will not be adequate against late model MiG-21s or the newer Soviet fighters.
The TF-30-P-412 engine to be used in the F-14A aircraft is equipped with a new Iris type exhaust nozzle providing improvements in aircraft range that vary up to 8 per cent over the operating envelope. The engine has also been refined to reduce fuel consumption at significant mission conditions and has smokeless combustors. Pratt & Whitney delivered the first P-412 prototype F-14A flight test engine to Grumman in September 1970, and will commence production engine deliveries in February 1971. The development schedule for the F-14B's Advanced Technology Engine calls for an engine to be installed in one side of number seven F-14A in November 1971. Reconfiguration from F-14A to F-14B to accept the ATE will require only a minimum modification tot the basic airframe. Then, in June 1972, two ATEs will be installed for final flight test and evaluation that will lead to fleet introduction of the F-14B in December 1973.
The F-14B and F-14C (to be equipped with the F-14B powerplant and airframe but with advanced avionics currently under development) will have a combat thrust-to-weight ratio greater than 1.16 which will provide these aircraft much higher air-to-air combat performance than any known projected Soviet fighters. The F-14A at combat weight (gun and four Sparrow missiles) will have a thrust-to-weight ratio of 0.84, and the acceleration characteristics will be greater than that of the best Soviet fighter in production today. Acceleration of the F-14 equipped with the ATE from 0.8M to 1.8M will require only 1.27 minutes, or a 40 per cent improvement over the best Soviet fighter today. Retrofitting of all F-14As with the ATE, which is scheduled to take place as soon as the new engine becomes available , will cost only approximately $6,000 per aircraft.
The multi-shot AWG-9/Phoenix missile system is an integral part of the F-14 design and has influenced the aircraft's size, weight and cost. However , the gross weight increase has been held to about 1 per cent and the cost increase to about 10 per cent over an aircraft incorporating a digital version of the AWG-10 (F-4J) fire control system. The Navy sees the AWG-9/Phoenix missile system as essential for shooting down or diverting missile-carrying aircraft before they reach missile launchrange, and for destroying air and surface launched cruise missiles after they have been launched.
When the US Congress denied further F-111B funds in Fiscal Year 1969, development of the Phoenix, which had originally been designed for this type, was reoriented to the F-14A. The additional cost to modify the AWG-9 missile control system for the F-14 is $129 million, including reconfiguring from a side-by-side to a tandem seating arrangement and incorporating the capability to fire Phoenix, Sparrow, Sidewinder, Agile and a 20-mm gun. The total R & D costs for the missile system are $414 million, of which over 91 per cent has already been expended.
A fully proven F-14A weapon system is scheduled to undergo fleet introduction only 51 month after contract award to Grumman in January 1969. The development programme will involve a total of fourteen aircraft, including twelve for flying trials. Grumman's flight test programme will demonstrate an operational air-superiority fighter capability before the initial Navy Board of Inspection and Survey (BIS) trials, scheduled to begin 17 month after first flight, or approximately one-half the time usually allowed. Grumman will also demonstrate the air-to-ground operational capability of the F-14A during initial squadron training, which is scheduled less than two years after first flight.
To help achieve these goals, Grumman has added several new facilities to its unique Calverton complex near the eastern tip of Long Island. These include:
An Automated Telemetry Station, to which flight test data will be telemetered, processed by computers and displayed in real time. Flight test instrumentation is built around a new pulse code modulation (PCM) system capable of recording 600 parameters, and telemetering approximately 300 parameters to the ground.
An anechoic chamber, the largest of its kind, capable of housing a fully equipped F-14 for evaluation of weapon system compatibility and electromagnetic (EM) interference operational performance in its own EM environment. The building housing the chamber is 26.5 x 26.5 m and 12.8 m (87 x 87 x 42 ft) is fully equipped, and will enable the aircraft to radiate with its radar and jammers within the chamber, thus preventing Russian trawlers off the coast of the US from recording these classified signals.
An improved Identification Friend or Foe (IFF) tracking station and operations centre will also serve the F-14 test programme. Grumman's F-14 operations centre at Calverton will serve as the tracking and control headquarters of the flight test system, and will be aided by a computerized flight test system (CFTS) and a management information system (MIS). Outputs from these two systems will be visually displayed at the centre and will present alternatives to scheduled events, should weather conditions or equipment/component failures arise, providing immediate alternate choices that will cause minimum time loss in the programme.
To accomplish the interface of an operational avionic system with the aircraft 17 month after first flight, the F-14 weapon system integration and test programme has been divided into three parts: (1) hardware and software testing to meet equipment specification requirements; (2) hardware and software integration testing to be gradually built up into a fully operational and compatible system; and (3) evaluation and performance demonstration of the entire weapon system. Following the first part, each supplier will provide Grumman with an acceptance-tested component of the weapon system, the integration test phase will be initiated and both software and hardware components integrated in the Systems Integration Test Station (SITS) at the Pacific Missile Range, Point Mugu, California. SITS will be described in greater detail later in this article.
Grumman's design work on the F-14A actually dates back to 1966 when the company commenced a series of Navy R & D studies of advanced inlet and ejector designs and supported a series of product improvement tests for the F-111B. The company had tested some 900 aerodynamic variations and 540 propulsion inlet and ejector configurations by the end of the F-14 contract definition. By the time of the first flight, Grumman will have accumulated an estimated 27,000 hours of wind tunnel tests involving 29 basic model types for aerodynamics, propulsion, structural loads, spins, store separation, etc.
Structural testing of flight hardware will involve two complete static test airframes and various key components, including titanium wing box beams and boron epoxy stabilizers. Grumman is installing a structural data acquisition system in Plant 5 at Bethpage to ensure that structural tests confirm the integrity of the basic design at the earliest possible date and also provide the full envelope clearances required during flight test programme. Early in 1971, the fatigue test programme will begin on an airframe with forgings and assemblies fully representative of the final production aircraft. Grumman plans to verify twice the anticipated life by the first F-14 squadron deployment and to continue through four time life or to destruction, whichever comes first.
Like other aerospace manufacturers, Grumman is continuously refining its manufacturing techniques and processes, many of which are being utilized in the F-14A programme.
Grumman is successfully hot-forming more than 2,000 titanium parts per month without an initial cold-preforming operation by means of a company-developed advanced hot-forming process performed on twin 75-ton presses. More than 25,000 titanium parts have been produced with the process constituting more than 350 different designs, including skins with compound curvatures, drawn rings, and channel-shaped members with joggles. The one-step process achieves cost savings of up to two-third of that of the two-step process.
Grumman has simulated more than 12,000 flight hours with a box beam produced from titanium fabricated by several advanced processes including electron-beam (EB) welding. Manufacture of an EB welded wing carry-through box for the F-14A will provide a saving of 500 kg (1,100 pounds) over conventional techniques.
An integrated facility to manufacture all aluminium, steel and titanium sheet metal parts up to 1.5 x 3.7 m (5 x 12 foot) blank sizes provides blanking, forming, heat-treating, finishing and inspection at a production rate of 2 million pieces 4.25 million pieces annually in 1971. All finishing operations will eventually be handled by the integrated facility.
A 3,380 sq m (36,400 square foot) skin fabrication area is capable of fabricating aluminium and titanium skins up to 6.1 x 3.7 m (20 x 12 feet). Also an integrated operation, it receives the raw material, shears, cleans, heat-treats, stretches, drills and trims them, before passing them on to near-by machining, chem-milling and finishing facilities. Production capability is 160 skins daily.
The F-14 will be the first aircraft designed from inception to utilize boron composite outer skins on the horizontal stabilizer over an aluminium honeycomb core. To avoid the weight penalty of mechanically fastening the composite fibrous skin to metal, the company uses a boron composite-titanium subassembly that is bonded to the honeycomb core.
Approximately 40 per cent of the F-14 surface area will be manufactured through adhesive bonding. Grumman will manufacture many of these structural components in its centralized bonding facility whose current production rate is 3,000 bonded assemblies per month.
Of the F-14A's total AMPR (Aeronautical Manufacturers Planning Report) weight, approximately 25 per cent will be titanium (carry-through, wing pivot, longerons and bulkheads, wing covers, engine frames, honeycomb face sheets, formed fuselage keel and tubing), about 4 per cent will be non-metallic materials (boron-epoxy on horizontal tail skin surfaces, fibreglass epoxy on nose radomes and strakes, fluorosilicones for sealants, modified epoxies for adhesives, and acrylics for windshield and canopy), 36 per cent will be alluminium, and 15 per cent steel.
Grumman initiated facilities and tooling studies for the F-14 programme ion 1965 and has expended almost $55 million in enlarging its manufacturing capabilities for lightweight, high-strength structures, plus $11 million in weapon system integration, test and development facilities. The F-14A will be constructed on a modular basis with each major structural component, including wing modules, forward, mid and aft fuselage, assembled and tested in its own area and completed as an end-product configuration functionally ready for joining and final assembly.
Grumman attributes its ability to use the modular technique in structural design to a company-developed, computerized integrated design analysis system (IDEAS) for accurately sizing internal loads to permit butt joining of integrally flanged frames at module splice areas, instead of overlap joining. The technique eliminates weight penalties normally associated with other modular designs, because the requirement for backup frames is eliminated. IDEAS cost $750,000 to develop.
Production and systems testing
The first F-14A aircraft is 95 per cent of the way toward its first flight, Grumman officials told Interavia in an interview. As far as the performance of the entire F-14 development programme is concerned Grumman officials report that all milestones are being met. The aircraft is within weight, in fact, within six-tenth of one per cent of the specification guarantee. It is on cost with effective cost management procedures being employed to monitor and report potential trouble spots. The F-14 design has been completed for some time. Thorough analysis and extensive wind tunnel tests confirmed performance and weight as meeting Navy requirements. The programme is ahead of schedule at the time of writing with the first flight expected to take place at least one month ahead of the January 30, 1971 contractural date.
The first four aircraft are currently on the Grumman production line in various stages of completion. The Number 1 aircraft was scheduled to be completely assembled and shipped to Grumman's flight test operation facilities at Calverton, New York by mid-October. Installation of the twin TF30-P-412 turbofans is taking place at Calverton. The current production schedule calls for additional aircraft to come off the line at the rate of one per month, beginning this month (November).
During the contractual mock-up review milestone completed by key US Navy and civilian personnel three month after contract award, all aspects of the F-14 were examined, from structural design, through cockpit arrangement, to maintenance concepts, and close Navy/Grumman co-operation resulted in design refinements and weight and cost reductions. The F-14A development programme has already peaked with approximately 2,500 engineering and currently involves 1,500 production personnel. Some of the design/production aids being used by this Grumman work force at the present time are now discussed.
Grumman's Engineering Mock-up and Manufacturing Aid (EMMA) simulates a first-article production aircraft in all essential details and serves as a key tool for flight hardware engineering and manufacture. EMMA is leading construction of the production F-14A aircraft by five months and is enabling Grumman engineers to shorten schedules and improve shop efficiency. Equipment, harnesses, piping and ducting installation confirm space factors, line runs, and isntallation designs. EMMA is used to solve production line problems without holding up flight hardware manufacture and will remain "alive" for the duration of the contract. At Navy direction EMMA can serve as the basis for modifications and for investigations of other F-14 versions.
The full-scale wing rear beam functional mock-up serves a similar purpose. A key design area of the wing, it provides critical information with respect to flap operation. Grumman also constructed a one-half scale titanium box beam similar to the F-14 design for combined torsion and bending tests. No failure or distortion occurred in cycling for two time aircraft life. Well after this point in testing, failure occured at a tool mark in the parent material, not in a welded seam.
The F-14 Systems Integration Test Stand (SITS) was delivered early in 1970 to the US Navy Missile Center at Point Mugu, California, where it will test the complete F-14 avionics system. SITS will permit fewer, more efficient and safer test flights through its initial on-the-ground systems integration and simulation use, and later in real time test flight surveillance. About 160 Grumman people are presently working on the SITS project at Point Mugu.
The AWG-9 airborne weapon control system (AWCS) completed ground testing at Hughes Aircraft in Culver City, California sometime ago, and flight testing in a modified Navy TA-3B is continuing at Point Mugu. Its long range radar permits target detection and tracking to altitudes of 30,480 m (100,000 feet) and ranges to 161 km (100 miles).
Initial static and operational sweep tests of the full-scale wing pivot test article, completed in March 1970, were subcontracted to Vought Aeronautics Division of LTV Corporation in Dallas, Texas. Pivoting load and operational sweeping tests at ambient and -43°C (-45°F) temperatures were satisfactory. A production design test specimen was delivered to Vought and fatigue testing equivalent to two times operational life, or 12,000 cycles, is planned. A failure did occur in one of the lugs during full-scale testing. This has been corrected by lug redesign and tests undertaken to verify the redesign.
Two prototype boron stabilizers have been fabricated. One has undergone static test, in which it was ultimate load tested at room temperature, and then load-to-failure tested at elevated temperatures. The second stabilizer has been used for ground vibration surveys at room and elevated temperatures to determine change in elastic properties.
Wind tunnel testing of the final high-lift configuration at Ames Research Center was initiated in late March 1970 and completed recently. Results of these three-quarter scale model tests confirmed the design maximum lift coefficient for carrier take-off and landing performance.
The engine exhaust system, incorporating the convergent-divergent (C-D) iris nozzle, self-cooled by engine-supplied fan discharge air, eliminates a secondary cooling system with its associated drag and weight penalities. More than 7,000 hours of wind tunnel testing were involved in the C-D Iris nozzle design. The TF-30 powered F-14 propulsion system achieved propulsion target levels with this design. The development changes to the inlet design incorporate extensive scale model wind tunnel testing at Grumman, at Ames Research Center, and preliminary full scale inlet-engine compatibility testing at the Grumman Calverton facility.
These engine-inlet tests helped finalize a single inlet design which is TF-30-P-412 (20,000 lb thrust) and ATE (28,000-30,000 lb thrust) compatible . Testing included inlet, recovery and distortion evaluation, trimming procedures, accessory equipment, loading and power extraction.
Fuel system testing was initiated in July 1970 at Calverton where extensive fuel storage, pumping and related capabilities are available. The fuel test stand implements a programme that evaluates all major F-14 fuel system characteristics including volume gauging, transfer rates, etc.
The Environmental Control System (ECS) is being simulated and tested. The principal test stand is essentially a mock-up of the cockpit section. Initially, the ECS mock-up was used for development testing of the airblast rain removal, rain repellant rake, and windshield anti-icing configurations. The test programme was sub-contracted to Republic Division of Fairchild Hiller at Farmingdale, New York. The same cockpit section, modified for use in the Grumman environmental laboratories, tested canopy defogging and system noise level. The mock-up is also undergoing electronic equipment cooling distribution, temperature control and ECS performance tests.
Since EMMA flight controls are manually, not hydraulically, operable, flight control dynamics will be simulated on the flight control hydraulics stand in the Grumman systems centre, duplicating the entire flight control system, including autopilot and Mach sweep programmer. Moving and fixed base simulators at Grumman are being used to evaluate and refine the F-14 flying qualities with the pilot in the loop, and include predicted F-14 aerodynamic, inertial, flight control and engine thrust response characteristics.
Grumman officials report that major subcontract work is proceeding on schedule. The major part of the F-14A is being built in Long Island plants, while approximately 30 per cent of the aircraft is being produced by subcontractors throughout the USA. Key elements include jet engine pods from Rohr Corporation, Chula Vista, California; aft fuselage from Republic Division of Fairchild Hiller, with the parent company supplying vertical stabilizers; slats, flats and spoilers from Karman CorporationM landing gear, etc. from Bendix Corp.
Present commitments are for 12 research, development, test and evaluation (RDT&E) aircraft. Grumman originally received $40 million of Fiscal Year 1969 funds for initial work on the first six aircraft comprising Lot I. In December 1969, $107.6 million of Fiscal Year 1970 money was appropriated for continuing work on the Lot I protion of the contract. The ceiling price of the Lot I contract is $388 million, and the US Government is obliged to provide the remainder of the funding over the period of Fiscal Year 1971-1972. In January 1970 the Naval Air Systems Command exercised its option for the second six RDT&E aircraft constituting Lot II. Grumman received $110 million for Fiscal Year 1970 funding to completely cover this option, and $4.5 million for advanced procurement.
To date, a total of $503 million has been appropriated for the development of the F-14A. Fiscal Year 1971 funding includes $517 million for 26 aircraft plus additional tooling required to increase the production rate, $80.9 million for initial spares, and $60.1 million for long lead time items required for Fiscal Year 1972. Grumman's R&D contract has penalties and awards based on its performance in meeting its contract guarantees. Grumman's guarantees and some of the penatlies for not meeting them follow: cost; weight empty ($440,000 for each 100 lb overweight); minimum approach speed ($1.056 million for each knot fast); acceleration time at altitude ($440,000 for each second slow); specific range or escort radius ($1 million for each 10 nautical miles short); maintainability ($450,000 for eac hextra maintenance man-hour per flight-hour).
The contract also contains a predetermined price decrease for slippage in the delivery of the five aircraft to the Navy Board of Inspection and Survey trials. This decrease will be at the rate of $5,000 per aircraft per day, not ot exceed the sum of $600,000 per aircraft or $3 million altogether. The Navy has no obligation to accept the aircraft if any of the minimum performance guarantees are not met. If this happens, the Navy can either require Grumman to correct the aircraft to meet the minimum requirement of agree to an equitable reduction in contract price. On the other hand, the incentive arrangement allows Grumman to maximize its profits by producing an aircraft which exceeds performance requirements, while being produced at the lowest actual cost.
Grumman believes that it will meet its maintainability as well as all of its other guarantees, and its Integrated Logistic Support (ILS) project is aimed toward this end as well aas to provide the Navy with an operational fighter aircraft which is completely supportable from its initial introduction into the Fleet. The Navy's RFP for the F-14 included many new ILS requirements such as a programme plan for maintainability . Also required by the Navy as government furnished equipment is the Versatile Avionics Shop Test System (VAST), an automated avionics test equipment system designed to test faulty units following their removal from the aircraft. A summary of key elements in Grumman's minimum maintenance and maximum supportability programme for the F-14 allows:
Engine accessibility - The nacelle pod installation of the powerplants provides rapid access for both routine inspection or engine oil replacment, and more than 80 per cent of the engine accessory corrective maintenance can be accomplished with the clamshell doors in the open position. Engines may be removed or replaced from the rear without jacking the aircraft and from the side by jacking one main landing gear wheel eight inches (engines are interchangeable for the right and left nacelles). Removal and replacement time of each engine by four maintenance men is three hours.
Avionics equipment checks - In addition to automatic inflight fault detection and indication of failure of a replaceable assembly on the missile control officer's tactical information display, 80 per cent of the avionic equipment is accessible for immediate maintenance without work stands. Lowering of the nose landing gear strut eight inches will provide additional avionic accessibility. Sequential removal is not required to gain access to avionics equipment located behind the hinged side access doors with latches or quickrelease captive fasteners. Avionics removal time is minimized by instant disconnects and release mounts.
Flight deck movement of aircraft - Movement of the F-14 with or without its engines on the flight or hangar deck can be accomplished either with a tractor or a spotting dolly. An ultra high-frequency data link signal for alignment reduces the deck clutter of umbilical cables and relative velocity computers normally required for inertial navigation system (INS) alignment.
While F-14A prototype construction continues, F-14B and F-14C engineering development is progressing. As mentioned earlier, planning calls for the F-14As to be operational by April 1973. As the 67th F-14A comes off the line, production is scheduled to switch to the more powerful B-version. First introduction of the F-14C all-weather air-to-ground weapon delivery version with an advanced avionics system for improved fire control will not take place until at least 1976, and probably later. Grumman is also doing some preliminary investigation on an RF-14 reconnaissance version as a possible replacement for RF-4Bs and RA-5Cs late in the 1970s.
If the F-14 development and production programme continues to progress as it has so far, without serious incident or delay, Grumman will show by its own example the leve lto which the US aerospace industry is capable of rising in airborne weapons systems development. The US industry has had its problems in recent years, not the least of which is the present funding crisis it is now experiencing. An F-14A that meets its design specifications and proves itself upon introduction to the Fleet will be welcomed not only by Grumman but also by many other members of the US aerospace industry.
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