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VFAX / NACF - Navy Air Combat Fighter

Northrop knew that the performance of its YF-17 could quickly be enhanced. This, plus the greater air-to-ground payload inherent in its design, attracted the interest of the US Navy. With the help of McDonnell Douglas, the YF-17 evolved into the dual-purpose F/A-18 Hornet which will be the Navy's primary fighter and light attack plane well into the next century.

The Navy Air Combat Fighter (NACF) was intended to be a low cost complement to the operational F-14 fighter and a replacement for the F-4 and A-7 aircraft. The NACF resulted from the Department of Defense (DOD) effort to turn away from the increasingly complex top-of-the-line fighter aircraft, as exemplified by the Navy F-14 and the Air Force F-15, and to seek less expensive complements to these weapon systems. The NACF program was the result of several years of exchanges between Congress and the DOD regarding the type of aircraft considered most appropriate for future Navy use, and evolved from earlier Navy efforts to procure needed levels of VFAX combat aircraft.

The Navy initiated a program to develop a new VFAX in the early 1970s. On 28 August 1974 the Chief of Naval Operations released a formal VFAX operational requirement directing NAVAIR to perform industrial solicitation and full-scale development. The VFAX concept was by this time under management by NAVAIRís PMA-265. The aircraft that finally emerged from the VFAX concept was the McDonnell Douglas F/A-18 Hornet.

The VFAX aircraft was designed to replace two aircraft in the Navyís inventory, the F-4 Phantom II and the A-7 Corsair II. This program was reinstituting an old Navy policy, whereby, multimission requirements for attack and fighter, be incorporated into a single aircraft. Fighter and light attack missions had previously been assigned to various types of aircraft, particularly in the period prior to World War II and also in the 1950s. The Navy was now reverting to an old policy and designing a plane with a dual capacity as a fighter and an attack aircraft to meet new multimission requirements.

The passage of the FY1975 Defense Authorization Act had not signaled the end of congressional opposition to the VFAX. When the 1975 DOD appropriation bill came before the House Appropriations Committee, the Committee recommended deletion of all funds requested for the VFAX. However, the Senate Committee on Appropriations recommended the inclusion of $20 million for the VFAX [S. Report No. 93-1104, 93d Cong., 2d Sess. 174 (1974)]. This difference was finally resolved by the conference committee on the bill, which also recommended an appropriation of $20 million but indicated that the funds were to be spent on a new program element which was designated the NACF: "The Managers are in agreement on the appropriation of $20,000,000 as proposed by the Senate instead of no funding as proposed by the House for the VFAX aircraft. The conferees support the need for a lower cost alternative fighter to complement the F-14A and replace F-4 and A-7 aircraft; however, the conferees direct that the development of this aircraft make maximum use of the Air Force Lightweight Fighter and Air Combat Fighter technology and hardware. The $20,000,000 provided is to be placed in a new program element titled "Navy Air Combat Fighter" rather than VFAX, Adaptation of the selected Air Force Air Combat Fighter to be capable of carrier operations is the prerequisite for use of the funds provided. Funds may be released to a contractor for the purpose of designing tile modifications required for Navy use. Future funding is to be contingent upon the capability of the Navy to produce a derivative of the selected Air Force Air Combat Fighter design." [H.B. Report No. 93-1363, 93d Cong., 2d Sess. 27 (1974)].

The DOD Appropriation Act was enacted on October 8, 1974, as Public Law 93-437 (88 Stat. 1212). However, the language of the Act itself did not include any specific direction as to how the funds were to be spent. It stated only the following: "[T]he following sums are appropriated, out of any money in the Treasury not otherwise appropriated, for the fiscal year ending Juiie 30, 1975, for military functions administered by the Department of Defense, and for other purposes namely: * * * * * * * RESEARCH, DEVELOPMENT, TEST, AND EVALUATION, NAVY For expenses necessary for basic and applied scientific research, development, test, and evalution, including maintenance, rehabilitation, lease, and operation of facilities and equipment, as authorized by law; $8,006,914,000, to remain available for obligation until June 30, 1976."

While Congress was considering the relative merits of the VFAX, NACF, and ACF programs, both the Air Force and the Navy were moving ahead on their respective programs. On September 3, 1974, the Air Force solicited full-scale development proposals for the ACF from both GD and Northrop, whose prototype aircraft had been undergoing comprehensive flight test programs. At approximately the same time, the Chief of Naval Operations released the formal VFAX Operational Requirement and directed NAVAIR to prepare an industry solicitation for VFAX Contract Definition and full-scale development. However, in view of the language in H.R. Report No. 93-1363, quoted above, DOD directed NAVAIR to limit the planned solicitation to derivatives of the LWF and ACF designs. This limitation, the Navy believed, was in accord with the Congressional guidance provided in that report.

Since neither GD nor Northrop (the ACF competitors) had built carrier-capable aircraft, the Navy asked each contractor to develop a partnership arrangement with carrier-capable companies for the NACF procurement in accordance with Armed Services Procurement Regulation (ASPR) 4-117 (1974 ed.). After a period of discussion, MDC and Northrop entered into a teaming arrangement on October 2, 1974, with MDC as the prime contractor for the NACF effort. On that same day, GD and LTV also entered into a teaming agreement, which provided that GD would be the prime contractor to the Air Force and that LTV would be the prime contractor to the Navy for any derivative versions of the YF-16.

The agreement further provided that if the YF-18 were not selected by the Air Force, then GD would be the prime contractor to the Navy for the NACF. Those contractor relationships were approved by the Navy. On October 12, 1974, the Air Force, on behalf of the Navy, issued request for quotations (RFQ) No. N00019-75-Q-0029 to the ACF contractors. The RFQ was originally designed for the VFAX. however, as issued, it solicited proposals for the design, development, test and demonstration of the NACF. The RFQ called for a cost reimbursement type contract, incrementally funded in part, with proposals to be submitted on a cost-plus incentive- fee basis. It indicated that proposals should be based on the incorporation of the essential characteristics of the former VFAX into the design of the NACF, and that significant emphasis would be placed on the design-to-cost method of contracting and on life cycle costing. It also advised that proposals should include a technical proposal and trade-off analysis, a test and evaluation plan, a management/ capability/facility submission, a design to cost analysis, an ACF derivative analysis, a cost proposal, and an executive summary.

To support the contractor design effort called for by the RFQ, the Navy proposed to utilize approximately $12 million of the $20 million designated by the congressional conferees as available for the NACF program. By letter dated November 1, 1974, DOD so informed the Chairmen of the Senate and House Committees on Appropriations. Both Chairmen subsequently responded that their Committees had no objection to the proposed expenditures.

Preliminary responses from both LTV and MDC were submitted on December 2, 1974. Complete RFQ responses were received on January 13, 1975, and contractor technical discussions were held a few days later. LTV proposed two designs essentially based on the YF-16 model, the model 1601 and model 1600, while MDC proposed its niodel 267, which was essentially based on the F-17. The Navy regarded these initially proposed designs to be unacceptable for carrier use. However, both sets of designs were determined to merit further consideration as capable of being made acceptable. The Navy then entered into discussions with LTV and MDC, pointing out what it considered to be unacceptable areas in the proposals. Discussions and proposal revisions continued into March 1975, when LTV offered an additional design it designated the model 1602.

During this period, the Air Force, on January 13, 1975, announced the selection of the General Dynamics design, redesignated as the F-16, as the Air Force ACF choice over the F-17. This decision was explained by the Secretary of Defense at a January 14, 1975, news conference as follows: "In the ease of the YF-16 selection by the Air Force, that is one of those happy circumstances in which the aircraft with a higher performance happened to provide the lower cost. * * * We have carefully reviewed the data, and, according to the Air Force data, over a 15-year life cycle, with constant 1975 dollars, the savings for the Air Force by going in the direction of the YF-16 should amount to something on the order of $1.3 million in R&D, in production costs and in life cycle costs-operation to maintenance costs. * * *"

On April 4, 1975, the Navy solicited "best and final" offers from LTV and MDC. Also on that date, the original RFQ was redesignated request for proposals (RFP) No. N00019-75-R-0084 (for MDC) and RFP No. 00019-75-R-0085 (for LTV). Both RFPs were essentially the same (with certain clauses and provisions individually tailored to the proposals of the specific contractors) and essentially similar to the RFQ, except that the RFPs contemplated a letter contract and revised the contract fee arrangement from an incentive fee basis to an incentive fee/award fee basis. "Best and final" offers were received on April 15, 1975.

On May 2, 1975, the Navy announced the selection of the MDC design and the resulting award of sustaining engineering contracts to MDC ($4.4 million) and GE ($2 million), the engine developer. Both contracts were to last approximately 4 months, pending award of full-scale development contracts.

Although LTV's designs were in varying degrees based on the F-16 design, the Navy ultimately determined that only the MDC entry, which was based on the F-17 design not selected by the Air Force, was suitable for the Navy. As a result of that determination, the Navy selected the MDC entry, designated it the F-18, and on May 2, 1975, awarded sustaining engineering contracts to MT)C and also to General Electric Company (GE) (which is to develop the, engines for the aircraft).

After the Air Force selected the F-16 to be produced for the Tactical Air Command in 1975, and the Navy was directed by Congress to base the VFAX on either the YF-16 or YF-17 designs. Two of the companies having a major interest in the VFAX, which was redesignated the Navy Air Combat Fighter, paired with the F-16/17 builders; neither of the latter had experience in producing Navy carrier fighters. Vought as a prime contractor teamed with General Dynamics on a single-engined F-16 derivative, while McDonnell Douglas became the prime, paired with Northrop, on an F-17 derivative.

To meet Navy requirements, considerable improvements in areas such as combat radius and radar capability were incorporated, in addition to carrier suitability features. The resulting redesign was extensive and, when the McDonnell Douglas design was selected as winner in 1976, it was assigned the F-18A designation. The developed versions of the YF-17's YJ101 engines were redesignated F404s.

The formidable task of converting the land-based YF-17 lightweight day fighter into an all-weather fighter-attack aircraft capable of carrier operations with heavy ordnance loads required significant changes from the earlier configuration. Structural strengthening and a new landing gear design were required for catapult launches and arrested landings.

The aircraft gross weight rapidly grew from 23,000 lb for the YF-17 to a projected weight over 33,000 lb. The original YF-17 had a wingspan of 35 ft and a wing area of 350 sq. ft. For the F/A-18A the corresponding numbers are 37.5 ft and 400 sq. ft. While the basic aerodynamic concept of the YF-17 and the F/A-18A were essentially the same, the interior of the F/A-18A was completely redesigned.

Dimensions YF-17 F/A-18A F/A-18E
Span (without missiles)35.0ft 37.6ft 42.9ft
Length 56.0ft 56.0ft 60.2ft
Height 14.5ft 15.3ft 15.8ft
Tail span 22.2ft 21.6ft 23.3ft
Wheel track 06.9ft 10.2ft 10.45ft
Wing area 350sq ft 400sq ft 500sq ft
Empty 17,000lb21,830lb 30,600lb
Fighter configuration 23,000lb 34,700lb 47,900lb
Maximum 51,900lb 66,000lb

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