Ran in The Weaponeer on 15 April 1999

WD and AD team with contractor on a quick-reaction project for F/A-18

China Lake, CA-China Lake, Patuxent River and Boeing completed a quick-reaction, joint F/A-18 E/F project on Feb. 3. The F/A-18 Team successfully measured the noise and vibration environment that will affect the new Advanced Targeting Forward Looking Infrared (ATFLIR) pod. This was accomplished in one-third the normal time and with no impact on the ongoing, intensive F/A-18 E/F flight test program.

The design and acquisition of the new ATFLIR system for the Super Hornet started last year. Each new F/A-18E/F aircraft will have an ATFLIR installed as it comes off the Boeing assembly line on the semi-recessed, fuselage "cheek" station - just aft of the engine inlet. This is the station that normally carries an AMRAAM or Sparrow missile. During engineering and manufacturing development (EMD) of the F/A-18, it was suspected that the in-flight environment at this aircraft station may be significantly different from the A/B and C/D versions of the aircraft. These differences were identified in wind tunnel tests and verified during weapons separation testing. "It was vital to characterize this environment quickly so we could provide the correct design data to the new ATFLIR engineers," said Darrell Grandjean, project lead. "Any delay would result in a new ATFLIR that may not operate and may not even survive the in-flight environment."

In August 1998, the team started to characterize the environment on the E and F aircraft. They discussed the task with the Boeing Aircraft Company, and they provided cost estimates to conduct the tests using traditional methods. Unfortunately, the proposed test program would have had an alarming impact on the E/F flight-test schedule. The only way the team could conceivably measure the environment was to invent a stand-alone, internal, ATFLIR-shaped, noise and vibration system.

NAWCWD China Lake quickly responded to the challenge. The team presented an approach to NAVAIR, received a go-ahead and launched a three-month noise and vibration program during the second week of August. They decided to use the existing AN/AAS-46 TFLIR by replacing the laser power supply with a custom enclosure that contained very sensitive "brassboard" noise and vibration instrumentation. The plan included designing the hardware, performing a stress analysis, procuring long-lead hardware, building the test hardware, preparing a documentation package and completing an end-to-end checkout.

The project was barely under way when the schedule was shortened to 30 days for programmatic reasons. "But the team accepted this challenge and worked as a finely tuned instrument," said Grandjean. "We had to use many innovative processes and spend many late nights at work." For example, they designed the hardware with rough sketches and then worked closely with the craftsman during the hardware fabrication process. They documented the hardware during fabrication so they could concurrently perform the structural analysis.

These activities led to flight clearance for the full-flight environment of both the C/D and E/F aircraft.

"Buying hardware on such short notice was a real potential showstopper," said Grandjean. "We had to beat the bushes for hardware. Our NAWCAD teammate was able to dig up enough environmental sensor components to provide the first prototype unit. Meanwhile, the China Lake team expedited procurements with incentive fees. We knew that broken hardware and aggressive test schedules were always time consumers. To get around this we produced three sets of machined flight hardware and qualified the equipment for either the China Lake or Patuxent River range. Flight and telemetry frequency clearances at both bases were worked simultaneously to provide two test site choices.

During last week of September 1998, China Lake team members went to Patuxent River to perform the system integration and flight test of the system in an AN/AAS-46. "We established a collaborative agreement between NAWCWD and NAWCAD to blend our two test philosophies and ways of doing business," said Grandjean. "The team was now an integral blend of both China Lake and Paxtuent River participants with an ambitious attitude to proceed and succeed."

The joint team fitted the noise and vibration flight tests into the existing, hectic, E/F EMD flight test program. "Four weeks later, we successfully completed the flight testing," Grandjean said. "Both our team and Boeing continue to analyze this environmental flight data to ensure the new FLIR pod will be operationally effective in the fleet."