The McDonnell Douglas (now Boeing) F/A-18 Hornet is a twin-engine supersonic, all-weather carrier-capable multirole combat jet, designed as both a fighter and attack aircraft (F/A designation for Fighter/Attack). Designed by McDonnell Douglas and Northrop, the F/A-18 was derived from the latter's YF-17 in the 1970s for use by the United States Navy and Marine Corps. The Hornet is also used by the air forces of several other nations. The U.S. Navy's Flight Demonstration Squadron, the Blue Angels, has used the Hornet since 1986.
The F/A-18 has a top speed of Mach 1.8 (1,190 mph or 1,915 km/h at 40,000 ft or 12,190 m). It can carry a wide variety of bombs and missiles, including air-to-air and air-to-ground, supplemented by the 20 mm M61 Vulcan cannon. It is powered by two General Electric F404 turbofan engines, which give the aircraft a high thrust-to-weight ratio. The F/A-18 has excellent aerodynamic characteristics, primarily attributed to its leading edge extensions (LEX). The fighter's primary missions are fighter escort, fleet air defense, Suppression of Enemy Air Defenses (SEAD), air interdiction, close air support and aerial reconnaissance. Its versatility and reliability have proven it to be a valuable carrier asset, though it has been criticized for its lack of range and payload compared to its earlier contemporaries, such as the Grumman F-14 Tomcat in the fighter and strike fighter role, and the Grumman A-6 Intruder and LTV A-7 Corsair II in the attack role.
The Hornet saw its first combat action in 1986 during Operation El Dorado Canyon and subsequently participated in 1991 Operation Desert Storm and 2003 Operation Iraqi Freedom. The F/A-18 Hornet provided the baseline design for the Boeing F/A-18E/F Super Hornet, a larger, evolutionary redesign of the F/A-18.
Development:
Origins
The U.S. Navy started the Naval Fighter-Attack, Experimental (VFAX) program to procure a multirole aircraft to replace the Douglas A-4 Skyhawk, the A-7 Corsair II, and the remaining McDonnell Douglas F-4 Phantom IIs, and to complement the F-14 Tomcat. Vice Admiral Kent Lee, then head of Naval Air Systems Command (NAVAIR), was the lead advocate for the VFAX against strong opposition from many Navy officers, including Vice Admiral William D. Houser, deputy chief of naval operations for air warfare – the highest ranking naval aviator.
In August 1973, Congress mandated that the Navy pursue a lower-cost alternative to the F-14. Grumman proposed a stripped F-14 designated the F-14X, while McDonnell Douglas proposed a naval variant of the F-15, but both were nearly as expensive as the F-14. That summer, Secretary of Defense Schlesinger ordered the Navy to evaluate the competitors in the Air Force's Lightweight Fighter (LWF) program, the General Dynamics YF-16 and Northrop YF-17. The Air Force competition specified a day fighter with no strike capability. In May 1974, the House Armed Services Committee redirected $34 million from the VFAX to a new program, the Navy Air Combat Fighter (NACF), intended to make maximum use of the technology developed for the LWF program.
Redesigning the YF-17
Though the YF-16 won the LWF competition, the Navy was skeptical that an aircraft with one engine and narrow landing gear could be easily or economically adapted to carrier service, and refused to adopt an F-16 derivative. On 2 May 1975 the Navy announced its selection of the YF-17. Since the LWF did not share the design requirements of the VFAX, the Navy asked McDonnell Douglas and Northrop to develop a new aircraft from the design and principles of the YF-17. On 1 March 1977 Secretary of the Navy W. Graham Claytor announced that the F-18 would be named "Hornet".
Northrop had partnered with McDonnell Douglas as a secondary contractor on NACF to capitalize on the latter's experience in building carrier aircraft, including the widely used F-4 Phantom II. On the F-18, the two companies agreed to evenly split component manufacturing, with McDonnell Douglas conducting final assembly. McDonnell Douglas would build the wings, stabilators, and forward fuselage; while Northrop would build the center and aft fuselage and vertical stabilizers. McDonnell Douglas was the prime contractor for the naval versions, and Northrop would be the prime contractor for the F-18L land-based version which Northrop hoped to sell on the export market.
The F-18, initially known as McDonnell Douglas Model 267, was drastically modified from the YF-17. For carrier operations, the airframe, undercarriage, and arrestor hook were strengthened, folding wings and catapult attachments were added, and the landing gear widened. To meet Navy range and reserves requirements, McDonnell increased fuel capacity by 4,460 pounds (2,020 kg), by enlarging the dorsal spine and adding a 96 gallon fuel tank to each wing. A "snag" was added to the wing's leading edge and stabilators to prevent a flutter discovered in the F-15 stabilator. The wings and stabilators were enlarged, the aft fuselage widened by 4 inches (102 mm), and the engines canted outward at the front. These changes added 10,000 lb (4,540 kg) to the gross weight, bringing it to 37,000 lb (16,800 kg). The YF-17's control system was replaced with a fully digital fly-by-wire system with quadruple-redundancy, the first to be installed in a production fighter.
Originally, it was planned to acquire a total of 780 aircraft of three variants: the single seat F-18A fighter and A-18A attack aircraft, differing only in avionics; and the dual-seat TF-18A, which retained full mission capability of the F-18 with a reduced fuel load. Following improvements in avionics and multifunction displays, and a redesign of stores stations, the A-18A and F-18A were able to be combined into one aircraft. Starting in 1980, the aircraft began to be referred to as the F/A-18A, and the designation was officially announced on 1 April 1984. The TF-18A was redesignated F/A-18B.
Northrop's F-18L
Northrop developed the F-18L as a potential export aircraft. Since it was not strengthened for carrier service, it was expected to be lighter and better performing, and a strong competitor to the F-16 Fighting Falcon then being offered to American allies. The F-18L's maximum gross weight was 7,700 pounds (3,490 kg) (approximately 30%) lighter than the F/A-18A, via lighter landing gear, lack of wing folding mechanism, reduced part thickness in areas, and lower fuel-carrying capacity. Though the aircraft retained a lightened arresting hook, the most obvious external difference was removed "snags" on the leading edge of the wings and stabilators. It still retained 71% commonality with the F/A-18 by parts weight, and 90% of the high-value systems, including the avionics, radar, and ECM suite, though alternatives were offered. Unlike the F/A-18, the F-18L carried no fuel in its wings and lacked weapons stations on the intakes. It had three underwing pylons on each side instead.
The F/A-18L version followed to coincide with the US Navy's F/A-18A as a land-based export alternative. This was essentially an F/A-18A lightened by approximately 2,500 to 3,000 pounds (1,130 to 1,360 kg); weight was reduced by removing the folding wing and associated actuators, by implementing a simpler landing gear (single wheel nose gear and cantilever oleo main gear), and change to a land-based tail-hook. The revised F/A-18L included wing fuel tanks and fuselage stations of the F/A-18A. Its weapons capacity would increase from 13,700 to 20,000 pounds (6,210 to 9,070 kg); largely due to the addition of a third underwing pylon and strengthened wingtips (11 stations in total vs 9 stations of the F/A-18A). Compared to the F-18L, the outboard weapons pylons are moved closer to the wingtip missile rails. Because of the strengthened non-folding wing, the wingtip missile rails were designed to carry either the AIM-7 Sparrow or Skyflash medium-range air-to-air missiles, in addition to the AIM-9 Sidewinder as found on the F/A-18A. The F/A-18L was strengthened for a 9 g design load factor compared to the F/A-18A's 7.5 g factor.
The partnership between McDonnell Douglas and Northrop soured over competition for foreign sales for the two models. Northrop felt that McDonnell Douglas would put the F/A-18 in direct competition with the F-18L. In October 1979, Northrop filed a series of lawsuits charging that McDonnell was using Northrop technology developed for the F-18L for foreign sales in violation of their agreement, and asked for a moratorium on foreign sales of the Hornet via McDonnell Douglas. The case was resolved in 1985 when McDonnell agreed to pay Northrop $50 million for complete rights to the design, with no admission of wrongdoing. By then Northrop had ceased work on the F-18L, and most export orders were captured by the F-16 or the F/A-18.
Into production
During flight testing, the snag on the leading edge of the stabilators was filled in, and the gap between the Leading edge extensions (LEX) and the fuselage mostly filled in. The gaps, called the boundary layer air discharge (BLAD) slots, controlled the vortices generated by the LEX and presented clean air to the vertical stabilizers at high angles of attack, but they also generated a great deal of parasitic drag, worsening the problem of the F/A-18's inadequate range. McDonnell filled in 80% of the gap, leaving a small slot to bleed air from the engine intake. This may have contributed to early problems with fatigue cracks appearing on the vertical stabilizers due to extreme aerodynamic loads, resulting in a short grounding in 1984 until the stabilizers were strengthened. Starting in May 1988, a small vertical fence was added to the top of each LEX to broaden the vortices and direct them away from the vertical stabilizers. This also provided a minor increase in controllability as a side effect. F/A-18s of early versions had a problem with insufficient rate of roll, exacerbated by the insufficient wing stiffness, especially with heavy underwing ordnance loads.
The first production F/A-18A flew on 12 April 1980. After a production run of 380 F/A-18As (including the nine assigned to flight systems development), manufacture shifted to the F/A-18C in September 1987.
Improvements and design changes
In the 1990s, the U.S. Navy faced the need to replace its aging A-6 Intruders, and A-7 Corsair IIs with no replacement in development. To answer this deficiency, the Navy commissioned development of the F/A-18E/F Super Hornet. Despite its designation, it is not just an upgrade of the F/A-18 Hornet, but rather, a new, larger airframe using the design concepts of the Hornet.
Hornets and Super Hornets will serve complementary roles in the U.S. Navy carrier fleet until the Hornet A-D models are completely replaced by the F-35C Lightning II. The Marines have chosen to extend the use of certain of their F/A-18s up to 10000 flight hours, due to delays in the F-35B version.
Design
The F/A-18 is a twin engine, mid-wing, multi-mission tactical aircraft. It is highly maneuverable, owing to its good thrust to weight ratio, digital fly-by-wire control system, and leading edge extensions (LEX). The LEX allow the Hornet to remain controllable at high angles of attack. The wing is a trapezoidal shape with 20-degree sweepback on the leading edge and a straight trailing edge. The wing has full-span leading edge flaps and the trailing edge has single-slotted flaps and ailerons over the entire span.
Canted vertical stabilizers are another distinguishing design element, one among several other such elements that enable the Hornet's excellent high angle-of-attack ability include oversized horizontal stabilators, oversized trailing edge flaps that operate as flaperons, large full-length leading edge slats, and flight control computer programming that multiplies the movement of each control surface at low speeds and moves the vertical rudders inboard instead of simply left and right. The Hornet's normally high angle-of-attack performance envelope was put to rigorous testing and enhanced in the NASA F-18 High Alpha Research Vehicle (HARV). NASA used the F-18 HARV to demonstrate flight handling characteristics at high angle-of-attack (alpha) of 65–70 degrees using thrust vectoring vanes. F/A-18 stabilators were also used as canards on NASA's F-15S/MTD.
The Hornet was among the first aircraft to heavily use multi-function displays, which at the switch of a button allow a pilot to perform either fighter or attack roles or both. This "force multiplier" ability gives the operational commander more flexibility to employ tactical aircraft in a fast-changing battle scenario. It was the first Navy aircraft to incorporate a digital multiplex avionics bus, enabling easy upgrades.
The Hornet is also notable for having been designed to reduce maintenance, and as a result has required far less downtime than its heavier counterparts, the F-14 Tomcat and the A-6 Intruder. Its mean time between failure is three times greater than any other Navy strike aircraft, and requires half the maintenance time. Its General Electric F404 engines were also innovative in that they were designed with operability, reliability and maintainability first. The engine, while unexceptional in rated performance, demonstrates exceptional robustness under various conditions and is resistant to stall and flameout. The F404 engine connects to the airframe at only 10 points and can be replaced without special equipment; a four person team can remove the engine within 20 minutes.
The engine air inlets of the Hornet, like that of the F-16, are of a simpler "fixed" design, while those of the F-4, F-14, and F-15 have variable geometry or variable ramp air inlets. This is a speed limiting factor in the Hornet design. Instead, the Hornet uses bleed air vents on the inboard surface of the engine air intake ducts to slow and reduce the amount of air reaching the engine. While not as effective as variable geometry, the bleed air technique functions well enough to achieve near Mach 2 speeds, which is within the designed mission requirements.
A 1989 USMC study found that single seat fighters were well suited to air to air combat missions while dual seat fighters were favored for complex strike missions against heavy air and ground defenses in adverse weather—the question being not so much as to whether a second pair of eyes would be useful, but as to having the second crewman sit in the same fighter or in a second fighter. Single-seat fighters that lacked wingmen were shown to be especially vulnerable.
Operational history:
United States, Entry into service
McDonnell Douglas rolled out the first F/A-18A on 13 September 1978, in blue-on-white colors marked with "Navy" on the left and "Marines" on the right. Its first flight was on 18 November. In a break with tradition, the Navy pioneered the "principal site concept" with the F/A-18, where almost all testing was done at Naval Air Station Patuxent River, instead of near the site of manufacture, and using Navy and Marine Corps test pilots instead of civilians early in development. In March 1979, Lt. Cdr. John Padgett became the first Navy pilot to fly the F/A-18.
Following trials and operational testing by VX-4 and VX-5, Hornets began to fill the Fleet Replacement Squadrons (FRS) VFA-125, VFA-106, and VMFAT-101, where pilots are introduced to the F/A-18. The Hornet entered operational service with Marine Corps squadron VMFA-314 at MCAS El Toro on 7 January 1983, and with Navy squadron VFA-25 in March 1983, replacing F-4s and A-7Es, respectively.
The initial fleet reports were complimentary, indicating that the Hornet was extraordinarily reliable, a major change from its predecessor, the F-4J. Other squadrons that switched to F/A-18 are VFA-146 "Blue diamonds", and VFA-147 "Argonauts". In January 1985, the VFA-131 "Wildcats" and the VFA-132 "Privateers" moved from Naval Air Station Lemoore, California to Naval Air Station Cecil Field, Florida, and became the Atlantic Fleet's first F/A-18 squadrons.
The US Navy's Blue Angels Flight Demonstration Squadron switched to the F/A-18 Hornet in 1986, when it replaced the A-4 Skyhawk. The Blue Angels perform in F/A-18A and B models at air shows and other special events across the US and worldwide. Blue Angels pilots must have 1,350 hours and an aircraft carrier certification. The two-seat B model is typically used to give rides to VIPs, but can also fill in for other aircraft in the squadron in a normal show, if the need arises.
Combat operations
The F/A-18 first saw combat action in April 1986, when VFA-131, VFA-132, VMFA-314, and VMFA-323 Hornets from USS Coral Sea flew SEAD missions against Libyan air defenses during Operation Prairie Fire and an attack on Benghazi as part of Operation El Dorado Canyon.
During the Gulf War of 1991, the Navy deployed 106 F/A-18A/C Hornets and Marine Corps deployed 84 F/A-18A/C/D Hornets. F/A-18 pilots were credited with two kills during the Gulf War, both MiG-21s. On 17 January, the first day of the war, U.S. Navy pilots Lieutenant Commander Mark I. Fox and his wingman, Lieutenant Nick Mongilio were sent from USS Saratoga in the Red Sea to bomb an airfield in southwestern Iraq. While en route, they were warned by an E-2C of approaching MiG-21 aircraft. The Hornets shot down the two MiGs with AIM-7 and AIM-9 missiles in a brief dogfight. The F/A-18s, each carrying four 2,000 lb (910 kg) bombs, then resumed their bombing run before returning to Saratoga.
The Hornet's survivability was demonstrated when a Hornet took hits in both engines and flew 125 mi (201 km) back to base. It was repaired and flying within a few days. F/A-18s flew 4,551 sorties with 10 Hornets damaged including two losses. The two losses were U.S. Navy F/A-18s and their pilots were lost. On 17 January 1991, Lieutenant Commander Scott Speicher of VFA-81 was shot down and killed in the crash of his aircraft. An unclassified summary of a 2001 CIA report suggests that Speicher's aircraft was shot down by a missile fired from an Iraqi Air Force aircraft, most likely a MiG-25. The other F/A-18, piloted by Lieutenant Robert Dwyer was lost over the North Persian Gulf after a successful mission to Iraq; he was officially listed as killed in action, body not recovered.
As the A-6 Intruder was retired in the 1990s, its role was filled by the F/A-18. The F/A-18 demonstrated its versatility and reliability during Operation Desert Storm, shooting down enemy fighters and subsequently bombing enemy targets with the same aircraft on the same mission. It broke records for tactical aircraft in availability, reliability, and maintainability.
Both U.S. Navy F/A-18A/C models and Marine F/A-18A/C/D models were used continuously in Operation Southern Watch and over Bosnia and Kosovo in the 1990s. U.S. Navy Hornets flew during Operation Enduring Freedom in 2001 from carriers operating in the North Arabian Sea. Both the F/A-18A/C and newer F/A-18E/F variants were used during Operation Iraqi Freedom in 2003, operating from aircraft carriers as well from an air base in Kuwait. Later in the conflict USMC A+, C, and primarily D models operated from bases within Iraq.
An F/A-18C was accidentally downed in a friendly fire incident by a Patriot missile when a pilot tried to evade two missiles fired at him and crashed. Two others collided over Iraq in May 2005. In January 2007, two Navy F/A-18E/F Super Hornets collided in midair and crashed in the Persian Gulf.
Source: Wikipedia