CRITICS OF THE McDonnell Douglas (MDC) F-18E/F argue that the aircraft does not represent enough of an advance over the current F-18C/D to justify the $63 billion programme cost. The US Navy , however, believes that the E/F structural upgrade restarts the growth cycle and prepares the aircraft to replace not only today's F-18s, but also Grumman F-14s, A-6s and EA-6s on aircraft-carriers after the turn of the century.
With sea trials scheduled to begin on 17 January (involving the first two-seater, aircraft F1, and the Navy's latest carrier, USS Stennis) the service's principal contention - that the E/F upgrade is critical to the continued carrier suitability of the F-18 - will be put to the test.
The F-18E/F came under attack in 1996 from the US General Accounting Office (GAO), which recommended that the US Department of Defense cancel the programme and continue buying F-18C/Ds until the Joint Strike Fighter (JSF) becomes available around 2010. The Congressional watchdog's central argument was that Navy concerns about the continued carrier suitability of the C/D have not materialised, and that today's aircraft could remain viable with "minor" upgrades.
The Navy totally disagrees. At the heart of the argument is the issue of recovery payload - the weight of fuel and weapons with which the F-18 can be returned to the carrier deck. In justifying development of the F-18E/F, the Navy forecast that weight growth during the C/D's operational life would erode the aircraft's recovery payload to an unacceptable degree. The GAO believes that it has evidence that the problem is not as severe as the Navy projected.
COST EFFECTIVE
"If we could have upgraded the F-18C/D, we would have," says Rear Adm Dennis McGinn, US Navy director of air warfare. Starting in 1998, MDC and the Navy studied 12 different F-18 upgrade configurations before determining that the E/F offered the best combination of cost and operational effectiveness - a conclusion upheld by several subsequent analyses. "They did a great engineering analysis, and came up with the F-18E/F," says McGinn
Capt Joe Dyer, the Navy's F-18 programme manager, should know better than most what could be done with today's C/D - in the late 1980s, he led the 'Red Team' set up to criticise the E/F upgrade. "The payload recovery issue with the C/D is the overarching imperative," he emphasises, adding that increased range and endurance "-is an important requirement - the C/D range needed to be fixed".
Dyer argues that the GAO, while ostensibly comparing the E/F with the C/D, in fact compared the aircraft with "-a mythical C/D, fixed but delivered at the C/D price". He dismisses the GAO's contention that larger external fuel-tanks and a strengthened landing-gear would overcome the C/D's operational deficiencies.
"The GAO gets low marks for system engineering," he says. Raising the landing weight to increase recovery payload, as proposed by the GAO, would require strengthening of the internal structure, further increasing weight, Dyer argues. "Increase weight, and now the approach speed is too fast. You have to increase wing area, which increases drag, so you have to re-engine the aircraft - that's what led to development of the E/F design," he says.
The GAO was encouraged in its belief by the fact that the Navy has increased the F-18C/D's maximum carrier-landing weight by 450kg, to 15,400kg, while the aircraft's empty weight has not grown as much as expected. Dyer acknowledges that F-18 squadrons have been allowed to operate the aircraft at a higher weight, but says that the dispensation brings with it operational restrictions.
Requirements for a higher wind-over-deck, shallower approach angle and limits on asymmetric stores carriage "-restrict the commander's room to manoeuvre", he says. "Those are burdensome restrictions in wartime."
RETURNING WEAPONS
The higher landing weight was introduced for F-18 patrols over Bosnia, enabling aircraft to be recovered with weapons unused. At the unrestricted carrier-landing weight of 15,000kg, the typical Bosnian stores load of some 1,500kg would have reduced the fuel available to an unacceptably low 900kg, so the landing weight was raised to increase the "first-pass" fuel allowance to almost 1,400kg.
This is still less than would normally be required for safe operations. The Navy says that carrier air wings usually set first-pass fuel at 1,800kg for day operations and almost 2,300kg for night operations. As pilots become more experienced, these allowances are reduced to 1,600kg day/2,000kg night.
Dyer says that the F-18C/D's recovery payload of 2,500kg, at the unrestricted landing weight of 15,000kg, allows around 700kg of weapons and 1,800kg of fuel to be returned to the carrier. The F-18E/F, he says, can be recovered with 1,800kg fuel and almost 2,300kg of weapons at its 19,500kg maximum carrier-landing weight - figures which do not yet benefit from the fact that the F-18E/F is now some 450kg below its specification weight.
The advent of precision-guided munitions has increased the importance of recovery payload, as the Navy does not want to have to drop valuable weapons just to get its aircraft back on to the carrier. Dyer points out that the Joint Direct Attack Munition and Joint Stand-Off Weapon, which will make up the bulk of the F-18's future weapons load, are both 900kg stores.
Dyer maintains that F-18 weight growth as a result of adding capability to the aircraft has encroached on fuel and is forcing commanders to trade off safety against flexibility of operations. McGinn describes flexibility as a "core competency" of carrier-based aviation. He says: "We know the future is uncertain. The antidote to uncertainty is flexibility. The growth [available] in the F-18E/F gives us that flexibility."
Conceived as one half of a double act, the F-18E/F assumed paramount importance for the Navy with cancellation of the companion A/F-X strike fighter. In addition to replacing existing multi-role F-18s, the Navy now plans to replace air-defence F-14s with the two-seat F-18F and is studying a command-and-control warfare (C2W) variant of the F to replace its EA-6Bs.
The Navy is also interested in the F-18E/F's potential as a tanker and as a precision-strike aircraft. These are all roles which would be difficult to perform with the F-18C/D because of range and endurance restrictions imposed by carrier operations.
UNDER PRESSURE
Emergence of the JSF programme has increased pressure on the F-18E/F, with the GAO comparing the projected $43.6 million flyaway cost of the F-18E/F unfavourably with the estimated $32.5 million flyaway cost of the Navy's JSF . "It's all a matter of timing," says McGinn. "The initial operating capability of the JSF is 2008 at the earliest. That is too long to wait for the capability and flexibility [needed] to increase the sphere of influence of the carrier battle group," he maintains.
The Navy plans to buy relatively few JSFs - just 300 for use as "first-day-of-war" stealthy strike aircraft. In contrast, the service plans to buy at least 1,000 F-18E/Fs. The GAO has questioned this number, noting that the original 1,000-aircraft plan consisted of 660 for the Navy and 340 for the US Marine Corps, which has decided not to procure the F-18E/F.
Dyer says that the Navy's original 660-aircraft requirement did not reflect the decision to replace F-14s with F-18Fs. Also, the service has an unfunded requirement for as many as 150 F-18C2Ws to replace its electronic-warfare EA-6Bs. The Navy's requirement for 1,000 aircraft "-is very real", he says.
The C2W is the first identified variant of the basic F-18E/F. MDC and F-18 principal subcontractor Northrop Grumman are spending their own money to explore the concept, conducting windtunnel, simulator and other testing, but are pushing for Navy funding to begin development in 1999. The team has chosen 2008 as the target in-service data for the F-18C2W (Flight International, 13-19 November, 1996, P17).
Based on the two-seat F-18F, the C2W has wingtip pods (housing receiver antennas) and electronic-attack pods (housing the jamming system) which can be carried under the fuselage or wing. The rear cockpit is modified to enable the C2W's two crewmembers to perform the task of the EA-6B's four crew.
Consideration of the F-18C2W, and a possible future precision-strike variant of the F-18F, is possible because of the greater carrier-based payload, range and endurance capability of the E/F. The airframe is 20% larger than that of the C/D, but internal fuel capacity is increased by one-third and the E/F can carry larger external tanks. The GAO has questioned the E/F's range capability, but McGinn says that early operational assessment (EOA) of the aircraft proved that "-the promises were true".
"Statements of [E/F] range performance are reality; they have been demonstrated in flight," says Dyer. With the same external tanks, he says, the E/F has 40-50% more range than does the C/D. The Navy's EOA involved flight tests of the first two F-18E/Fs to measure range performance, and results "-were a little better than predicted", Dyer says. The E/F is now projected to have a low-altitude interdiction-mission radius of action of 865km (465nm), compared with the specified 720km, and the C/D's 565km.
The Navy is also excited by the potential for use the F-18E/F as a "buddy" tanker. Offloading 2,900kg of fuel to another E/F at 610km would enable the refuelled aircraft to reach a radius of almost 1,600km. The new SLAMER stand-off missile would extend the aircraft's reach to 1,850km, the Navy calculates. The "tanker" aircraft, meanwhile, could remain on combat air-patrol to defend the carrier.
"The F-18C/D does not have enough endurance or fuel [to perform this mission]," the Navy argues.
This contention will shortly be put to the test: the GAO has succeeded in persuading Congress to direct the Navy to produce a report directly comparing the E/F with the C/D. The report is to be submitted in March, before the Defense Acquisition Board meets to decide whether or not low-rate initial production of the F-18E/F should proceed.
Source: Flight International
