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Saturday, November 1, 2003

New HUD for the Tomcat

A NavAir-Northrop Grumman team has applied off-the-shelf technology to equip the U.S. Navy’s F-14B with a new vertical display indicator group. Its benefits were demonstrated recently during Operation Iraqi Freedom.

John Gulick

The U.S. Navy’s F-14B pilots now enjoy greater situational awareness, thanks to the replacement of the combat aircraft’s vertical display indicator group (VDIG), the avionics portion of a larger upgrade program. The Naval Air Systems Command (NavAir) and Northrop Grumman made a point of using commercial off-the-shelf (COTS) technology to get the improved Tomcat avionics system to the fleet in the most cost-effective manner. Navy pilots have tested the results in combat in Iraq.

Justifying VDIG-R

Introduced in the late 1980s and incorporating more powerful engines, the F-14B retained the avionics of the older F-14A, which joined the Navy in the early 1970s. An F-14B avionics upgrade program began in the early 1990s, but, due to funding constraints, did not replace the VDIG. The later upgrade described here comprises the head-up display (HUD), a modular mission display processor (MMDP), and the vertical display indicator (VDI). This VDI includes the legacy multifunction display (MFD) assembly and serves as the mechanical mount and electrical interface for the HUD. ("Vertical" in this context refers to the orientation of the MFD.)

In order to implement the logistic engineering change proposal (LECP) to replace the B model’s VDIG, the NavAir-Northrop Grumman team first had to demonstrate that such a move made sense from both a mission and fiscal standpoint, especially during an era of dwindling budgets and curtailed programs. (The F-14Bs still had sufficient fatigue life to keep flying for an additional 10 to 12 years.) What was needed, the team reasoned, was a timely and cost-effective solution that could further update the F-14B, as the Navy looked forward to the more advanced F/A-18 Super Hornet and the multiservice Joint Strike Fighter.

The team found improvements were essential to erase the continual erosion of the VDI reliability, coupled with a marginally effective HUD. Fleet experience, plus test results validated by an early F-14B upgrade aircraft, confirmed what pilots had known for years: the VDI and HUD were simply inadequate and outdated for the mission. This meant that a new VDIG suite would be needed.

COTS Mandated

Against this background, Northrop Grumman launched a competitive procurement in 1997 that mandated a COTS avionics solution. After evaluating a number of competitive bids, Northrop Grumman selected Flight Visions Inc. (now CMC Electronics), Sugar Grove, Ill., to retrofit the Navy’s F-14B fleet with its SparrowHawk HUD and FV-3000 modular mission display processor. The company’s HUD originally was developed for commercial use and is flying on a number of turboprop trainer aircraft around the world.

Now, some five years after contract award, the fleet of 64 Navy F-14B aircraft is operational with an updated vertical display indicator group replacement (VDIG-R) system. The SparrowHawk HUD provides pilots a 25-degree total field of view with a 5-inch (12.7-cm) aperture in a unit lighter than the previous system. Features include a built-in-test capability for simplified maintenance and internal data logging and continuous testing to track system conditions during flight.

The HUD symbology is presented in a clear, sharp display with high brightness and clarity that allow pilots to increase their aiming envelope and benefit from greater overall accuracy and an enhanced combat safety margin.

All Navy F-14Bs with the new VDIG-R upgrade are assigned to squadrons at Naval Air Station (NAS) Oceana, Va. Those include VF-32, VF-11, VF-143 and VF-103, which support the Navy strike fighter role, and VF-101, which supports the F-14 training command.

The first modified F-14B with upgraded avionics flew in December 1999 just 14 months after contract award. Since then, 60 B models have received the VDIG-R modification at Oceania NAS, three at Point Mugu, Calif., and one at the Naval Air Test Center, Patuxent River Naval Air Station, Md. The last VDIG-R- equipped F-14B was delivered to the Navy on Aug. 8, 2003.

The HUD and MMDP (including mounting assembly) are both COTS components while the VDI is an F-14B legacy display that has been retained and reworked into the VDIG-R system.

The HUD includes an integral color camera that records an image of the pilot’s view through the dual combiner glass. It captures both the outside scene and the HUD symbology that is superimposed into the outside scene. The camera is mounted aft of the combiner glass and also provides turn and slip indicators and master caution light information.

The VDI includes a number of subassemblies:

  • The master arm panel that allows the pilot to interlock weapons;

  • An air combat maneuver guard panel, which allows all weapons–except the Sidewinder air-to-air missile–to be jettisoned unfired from the airplane;

  • Collision and master arm lights that alert the pilot to avoid the intake of any collision debris; and

  • Right and left fire warning lights that indicate fire in either of the aircraft’s two engines.

Also included is a HUD/VDI control panel that controls brightness and contrast levels, and provides barometric altimeter information. The upgraded F-14B also has a missile mode panel that contains missile prep and launch switches and controls to allow the pilot to cool the Sidewinder missile by flowing nitrogen to the missile’s head. And it is equipped with a data link group that provides fighter-to-fighter and carrier-landing information, as well as wing-sweep warning lights to indicate the position of the F-14 wings.

Equally important, the VDIG-R gives pilots enhanced situational awareness by providing primary flight information and navigation data on the HUD, as well as on the panel displays. Pilots, therefore, do not have to look down for essential flight information, such as dive angle, angle of attack, airspeed, altitude, horizon, velocity vector and steering cues. It also provides weather landing data, target, peak aircraft "g" loading, and heading and barometric altimeter readings, as well as weapons symbology projected in both the air-to-ground and air-to-air modes. With all this information provided at eye level, F-14B pilots have experienced less fatigue, achieved greater situational awareness, and improved combat proficiency during more than 10,000 flying hours with the VDIG-R fleet-wide.

In comparison to the previous windscreen projection system in the F-14B, the new HUD’s dual combiner glass doubles the field of view, provides more accurate symbol placement, and gives the pilot an improved working velocity vector and the flexibility to more easily change functions. The graphical display of aircraft information allows the pilot to assess aircraft performance and fly more precisely while reducing "eyes-in-the-cockpit" during critical flight maneuvers and weapons delivery operations.

Anything But Routine

Some may think the VDIG-R program was pretty straightforward. However, it was anything but routine. The system had to accommodate existing equipment in the F-14B cockpit, thus presenting challenges to both the hardware and software engineers. Consider the following:

  • First, CMC Electronics had to upgrade the existing VDIG subsystem with minimal aircraft changes and with no impact to the existing aircraft electrical and cooling requirements.

  • Second, the company had to modify and use the existing VDIG chassis to act as a structural and electrical adapter for the SparrowHawk HUD, while retaining the VDI cathode ray tube system and existing aircraft wiring.

  • Third, a new HUD had to be installed that met or exceeded the instantaneous field of view of the HUD previously installed in the F-14B Tomcat.

  • Fourth, CMC Electronics had to integrate a color capable HUD camera on the pilot display unit that intruded minimally into the pilot’s field of view, while maintaining coverage of all HUD symbology and visibility to external cockpit viewing.

  • And fifth, the new FV-3000 MMDP had to be a lightweight, modular computer for mission processing and capable of interfacing with existing aircraft data buses as well as with other installed interfaces.

On top of all this, the system had to be more reliable, more maintainable and, in the case of the HUD, surpass the performance of the more sophisticated HUD in the F-14D, which was built by Kaiser Electronics. Reliability was key. Specifically, mean time between maintenance actions (MTBMA) had to be improved over the current rate of 50 hours, and the program goal is to reach at least 750 hours MTBMA.

Aside from the hardware and software challenges, the program demanded a new perspective and understanding of how commercially available equipment could address military objectives in a more cost-effective manner. This represented an "unprecedented change in the make-up and nature of the national and defense industrial bases," wrote Assistant Secretary of Defense Arthur Money and Undersecretary of Defense Jacques Gansler, in a July 2000 memorandum to industry.

"Working a COTS solution into a military requirement is no cake walk, but definitely worth the effort," says Bob Atac, CMC Electronics’ vice president of military aviation. "Properly executed, you will end up with a COTS system meeting the performance and environmental requirements imposed on military specified equipment."

Seeing Action in Iraq

Flying from the USS Harry S. Truman, Navy VF-32 was the first VDIG-R equipped F-14B squadron to deploy in support of combat operations during Operation Iraqi Freedom. The Tomcats flew 239 combat sorties and 1,194.8 hours, according to Navy statistics. "More importantly, the squadron experienced no aborts [during the conflict] due to any avionics malfunctions," reports Chris Dalessio, a CMC Electronics field technician who spent four months on the Truman.

Mean time between failure (MTBF) rates for the HUD have "far exceeded the reliability achieved with the previous HUD," adds Steve Minnich, Navy program manager for the VDIG-R. Minnich admits that reliability statistics for the MMDP and VDI were, at first, "disappointing," but they now achieve MTBFs much greater than those of the legacy components. He also indicated that additional reliability enhancements are being incorporated into the system that should further increase MTBF.

Navy is Pleased

According to the F-14 program manager, Rear Adm. (Select) Peter Williams, "The new HUD provides significantly more flight information and weapon systems symbology than the original 1960s-design HUD."

In addition, the VDIG-R program has realized new synergies between the F-14 B and D models that should yield further benefits. Since the symbology produced for the HUDS in the F-14B and F-14D are similar, Navy pilots can more easily cross-train between models. And because the SparrowHawk HUD operates independently of the F-14B windscreen (unlike the original F-14B system) the Navy can replace the windscreen with a version more compatible with the night vision systems, such as on the F-14D.

The new HUD also incorporates electronic bore sighting that simplified the installation process and results in overall greater system accuracy. Previously the F-14B equipment had to be aligned manually, which required longer maintenance hours.

The Navy is apparently pleased with the VDIG-R program. Williams concludes, "There is no doubt the VDIG-R program has successfully demonstrated that you can use COTS combined with reworked U.S, military equipment to satisfy program requirements."

John Gulick is a public relations professional, freelance writer and co-author of Media Isn’t A Four Letter Word. He lives in Northern Virginia.

SparrowHawk HUD

Weight

17.25 pounds/7.8 kg.

Display Color

Green P-53 phosphor

Combiner

Single or dual

Dual Combiner

80 percent transmissivity

Field of View

25 degrees

Aperture

5 inches/12.7 cm

Draw Rate

135,000 degrees/sec maximum

Image Distortion

Less than 1 percent

Accuracy

0.0 to 2.0 milliradians

Contrast Ratio

1.3 to 1 against 10,000 foot lamberts

Reliability

3,500 hours MTBF

Environmental

Mil-Std-810E per Mil-5400 Class 1

Electromagentic Interference

Mil-Std-461D/462D

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