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AWST 29 April 1991Grumman Naval Aircraft Design Concepts
Evolving From Current F-14 Versions
STANLEY W. KANDEBO/BETHPAGE, N. Y.
Extended glove vanes and a slightly larger horizontal stabilizer are two external features that distinguish the Grumman Super Tomcat 21 from the F-14D. The aircraft is an advanced tighter based on the F-4D. A dedicated attack version at the Super Tomcat 21 also has been defined.
Design concepts developed by Grumman for emerging U. S. Navy fighter and attack requirements center on several advanced versions of the F-14 incorporat- ing evolutionary upgrades that can be added, in building block fashion, to the existing F-14D.
Although Grumman has been working on F—14 upgrades that would improve upon the current F-14D for several years, the latest designs and configurations were developed at the Navy’s request following cancellation of the A-12 attack aircraft program and postponement of a naval version of the advanced tactical fighter. “Grumman’s ground rules though were that each evolution had to be retrofittable into the F-14D,” Paul C. Bavitz, Grumman’s vice president for advanced F-l4 programs, said. This approach would allow the Navy to improve the aircraft through periodic block upgrades that it could define based on budgets and cost. This method also would allow the service to continue building F-14s until it decides where naval avi- ation should go, he said.
The evolutionary progression of the F- 14, defined by Grumman includes:
F-14 Quick Strike, an aircraft that improves the strike capability of the F-14 by adding stand-off weapon capability and more radar modes to the basic F-14D design. The improvements, which are common to technologies found in the F-15E and A-6F, could be retrofitted into all F- 14Ds. Design options also could improve survivability and reduce aircraft vulnera- bility. Super Tomcat 21, a fighter with improved engines, cockpits and sensors; increased-lift wing slats and flaps, and greater internal fuel capacity. This design also would address F-14 vulnerability, reliability and maintainability issues. The Super Tomcat 21 would feature al- most an order-of—magnitude reduction in the F-14D’s vulnerable areas. The aircraft also would incorporate a single-point maintenance panel, improved diagnostics and upgraded servicing systems that, when combined with its advanced avionics, would reduce unscheduled maintenance manhours per flight hour 40% when compared to the F-14A.
Attack Super Tomcat 21, a dedicated, interim attack aircraft derived from the Super Tomcat 21 that is capable of Mach 2 at high altitudes and 600 kt. speeds without afterburner at low altitudes. This attack aircraft, which would incorporate the Super Tomcat 21’s improvements and retain the fighter’s gun, also probably could carry the radar developed for the A-12. Adding thicker outer wing panels would boost the at- tack aircraft’s capability to carry fuel in- ternally. In addition to the Quick Strike and Super Tomcat 21 family, a more revolutionary strike fighter called the ASF-14 also was considered. With an R&D cost of about $4 billion, this aircraft could be de- veloped as a lower cost alternative to the naval version of the advanced tactical fighter by incorporating ATF engines and electronics into the F-14 airframe. It has received less attention in recent months than the other F-14 derivatives, Bavitz said. The Quick Strike retains the F-14D’s four fuselage rails, each with five substations, and the two wing weapon pylons, both with two substations, as well as the F-14’s two nacelle drop tank stations. Ac- cording to Bavitz, this aircraft configuration, which was studied before the A-12 was canceled, offers the Navy options to improve the ground attack capability of the F-14. Development costs could be $100-200 million, depending on the options select- ed. It would take about two years to develop and test the required software, and a Quick Strike aircraft could be available about one year after that, he said. A key aspect of the QuickStrike would be improvements made to the F- l4’s Hughes AN/APG-71 radar. Several of the improvements—including a synthetic aperture radar mode for high-resolution ground mapping; a Doppler beam sharpening mode for wide-sector, medi- um-resolution ground mapping; and a fixed target track mode—were developed for the F-15E’s AN/APG-70 radar and could be transitioned to the F-14 easily, Bavitz said. A sea surface search mode and a terrain avoidance feature would require some development, however, he said. Other sensor changes to the aircraft include addition of a Flir navigation pod and a targeting Flir pod that includes a laser range finder and designator. The Flir pods could be mounted on the aircraft’s wing pylons. Stand-off weapon capability could be added by modifying the F-14D’s stores management system. The required software for this change and the necessary weapon interface card for the F-14D’s encoder/decoder box would be based on items developed for the A—6F, Bavitz said.
The AYK-14 mission computer software required for aircraft radar and weapon controls, as well as the necessary display system software changes, also would be based on work done for the A- 6F, he said. These changes would allow the aircraft to carry laser-guided bombs, imaging-infrared Maverick missiles, Stand-off Land Attack Missiles and the data link pod required for SLAM control. Predeployment improvements scheduled for the F-14D already add Harpoon and HARM capa- bility, Bavitz said.
Other aircraft improvements would center on the cockpit, where color displays, a digital color map system and a head—up display for the Flir, all night-vision compatible, could be added. To increase mission radius, the aircraft’s wing pylons, already fitted with plumbing to handle drop tanks, could be fitted with a pair of 300-gal. drop tanks. They could also be fitted onto the aircraft’s aft fuselage weapons rails, which would allow Flir sensors to be carried on the pylons. This added fuel would in- crease the combat radius of the Quick Strike by about 80 naut. mi. when compared to the F-14D, Bavitz said. The two aircraft receiving the most attention from the Navy, however, are the Super Tomcat 21 and Attack Super Tomcat 21. According to Bavitz, a Super Tomcat 21, which, depending upon the mission, would have a flight radius 50- 100% better than the F-14D’s, could be built and begin flight test in about three years. Production deliveries could begin in about six years.
Grumman estimates the R&D cost of the aircraft and its sensors at “somewhat less than $2 billion,” which is about half the price the Defense Dept. plans to spend on F/A-18E/F airframe R&D. Central to the Super Tomcat 21 design is an improved high-lift system consisting of a composite single-slotted Fowler flap and a blunter, extended chord composite slat that more than compensates for the 2,000 lb. this design adds to the zero- eight of the F-14D. Grumman and the Navy have wind-tunnel-tested this system twice, and each time they found it pro- duced 25% more lift, through maximum angle of attack, than the current system did. With 25% more lift and only 5% more weight, this aircraft—equipped with two 280-ga1. drop tanks—could be launched from a carrier with zero kt. of minimum wind across the deck, Bavitz said. Air- craft recovery speeds are about 15 kt. lower than those of the F-14D, and the bring- back capability of the Super Tomcat 21 is about 2.5 times that of the A-6, he noted. Other external changes to the aircraft include using the F-14’s inboard wing gloves for fuel storage, a modification that requires an increase in the trailing edge of the aircraft horizontal stabilizer. But using the glove areas for fuel storage adds about 2,200 lb. of internally carried fuel. With two 280-gal. nacelle-mounted drop tanks, which the F-14 regularly carries and retains during supersonic flight, and two 300-gal. drop tanks mounted on the aircraft’s wing pylons, a Super Tomcat 21 armed with four air-to—ground and two self-defense missiles could be launched from a carrier carrying slightly less than 28,000 lb. of fuel. If 425-gal. nacelle-mounted drop tanks are substituted, more than 28,000 lb. of fuel can be carried. And increasing the size of the nacelle tanks does not affect weapons car- riage or release.
According to Bavitz, all mission calculations and signature characteristics were developed with each size of nacelle drop tank installed. The aircraft also can land on a carrier with both size tanks, he said. Gas turbine changes in the Super Tomcat 21 center on the installation of an aux- iliary power unit (APU) and use of a new powerplant, a version of General Electric’s F1 10-GE-129 improved performance en- gine adapted for the Navy. This power- plant would provide about 35% more thrust in mid-altitude, transonic flight conditions than the F110—400 engines now in the F—14D can provide. The new engine also would allow the aircraft to supercruise at about Mach 1.3 while carrying four air- to—air missiles, Bavitz said.
NOZZLE NEED REDUCED
A vectoring, axisymmetric engine exhaust nozzle also is a possibility, but the high angle of attack capability demonstrated by the F-14—77 deg—reduces the need for this type of nozzle. The APU was positioned where the F- 14D’s vent tanks are located, requiring the tanks to be moved to the vertical sta- bilizers. Inside the aircraft, the crew stations would feature large multicolor displays, helmet-mounted displays and sights, and a single-piece windscreen (AW&ST Apr.1, p. 17). Aircraft controls would be upgrad- ed to an electronic system. Very-high- speed integrated circuit (VHSIC)pro- cessor modules would be used to improve signal processing throughput and increase memory capacity. The processors also would be used to fuse all aircraft sensor data, providing one track for each target, regardless of which sensor is following the target. A shortfall in the F-14D, which has only sensor correlation capability, is that each sensor generates a track for each tar- get. VHSIC processors are considered a low-risk development item because they have been demonstrated in AYK-14 mis- sion computers, Bavitz said. Aircraft data links probably would remain the same as in the F—14D, with joint tactical informa- tion distribution system and the ASW— 27C being used. The most substantial changes to the aircraft are in the sensor area, however. The aircraft would incorporate a multimode radar that employs two-dimensional, passive, electronically scanned array technology. This would double the power of the AN/APG-71 radar now in the F-14D. It also could be equipped with inverse synthetic aperture radar and ground-moving target indicator modes. Other technologies could double the detection capability of the radar, Bavitz said.
Infrared search and track systems and a television camera system would be re- tained, and a navigation Flir and an at- tack Flir with a laser rangefinder/target designator would be added. For signature and drag reduction, the Flirs would be installed on either side of the aircraft in fairings ahead of two weapon launch rails, Bavitz said.
In addition to signature reduction techniques, other items will be added to improve survivability. The Super Tomcat 21 would carry more than twice the expendables, boosting the chaff/flare packets carried on the F—14D from 60 to 135. And if additional expendables are required, 320 more packets of BOL chaff can be carried in LAU-7 launchers. These would be mounted on the aircraft stations that normally carry AIM-9 missiles. “Almost half of the 2,000 lb. added to the aircraft were due to survivability items,” Bavitz said. The aircraft also would be equipped with an ALQ-l65 jammer with two trans- mitters, one being dedicated to low-band jamming. The F—14D now is equipped with a version of the jammer that has a single transmitter. The attack version of the aircraft, the Attack Super Tomcat 21, would be highly common with the fighter aircraft, and would retain most of its features, including the aircraft’s M61-A1 20—mm. gun and 700 rounds of ammunition, improved performance engines, APU, survivability improvements, advanced cockpits and improved high-lift system. The attack ver— sion would contain several more features that would improve strike capability. Global positioning satellite navigation capability would be added and when coupled with a terrain following/terrain avoidance radar mode, a navigation Flir, a digital data-driven moving map and a wide field of view head-up display, the aircraft would be capable of making high-speed, low-altitude penetrations. As an altemative, the radar developed for the A-12 could be installed, an option unavailable for the F/A-18 due to the size limitations of the aircraft, Bavitz said. The Attack Super Tomcat 21 would be capable of low-level speeds of 600 kt. without afterbumer and 700 kt. in full afterbumer while carrying ground attack weapons, Bavitz said. In an antisurface warfare configuration, the aircraft would be equipped with two HARMs, four Harpoons, two self-defense missiles and two 280-gal. nacelle-mounted drop tanks. The aircraft, which could de- liver nuclear weapons, also could carry up to 24 Mk. 82 bombs, 14 Mk. 83s, six Mk. 84s or six Harpoons on its fuselage and wing pylons.
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