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Navy Fixes Carrier Catapult to Launch Jets with External Fuel Tanks

Ford carrierThe Navy plans to fix the software on its new carrier-based electromagnetic catapult system so that it can launching F/A-18s and Growlers carrying additional external fuel tanks under the wings, service officials said.

The changes will be finished on the Navy’s Electro Magnetic Aircraft Launch System, or EMALS, in time for operational testing aboard the Navy’s first Ford-class carrier -- the USS Gerald R. Ford -- in 2017, said Navy Cmdr. Thurraya Kent.

In April 2014, the Navy discovered an issue during testing at its facility in Lakehurst, N.J., that prevents the system from launching F/A-18 Super Hornets and EA-18 Growlers that are configured with external wing tanks, service officials said.

“The Navy understands the issue and will address it with a software modification well before any planned operational launch and recovery of aircraft.  The fix will only involve a software change and will be completed well before any planned operational launch and recovery of aircraft,” she said.

The external fuel tanks, positioned beneath the wings on the E/A-18G Growler electronic jamming aircraft and F/A-18s, add additional stress to the aircraft when launched by EMALS, an issue which could wind up shortening the operational life of the aircraft.

The software updates are anticipated to begin by March of next year.

“No additional hardware or hardware changes to equipment already installed onboard CVN 78 are required, and there are no modifications required for any of the aircraft affected," Kent explained.

EMALS is a next-generation carrier-deck launch systems engineered to replace existing steam catapults and go on the services’ new Ford-class carriers.

The first EMALS system has been under construction for several years aboard the USS Gerald R. Ford, or CVN 78, the first in class of the new carriers expected to deliver to the Navy next year.

The USS Ford has been heavily criticized by lawmakers and government watchdog groups for cost overruns and delays with the new technologies. The ship is on track to come in under its congressionally-mandated cost cap of $12.9 billion.

“Two of the four catapults are completely built. The other two are almost built,” said Rear Adm. Thomas Moore, Program Executive Officer, Carriers.

The system is part of a new series of carrier-based technologies designed to significantly increase the sortie rate and engineer a tailorable catapult that can achieve the desired amount of power for a an aircraft’s dimensions and weight – all while reducing wear and tear on airframes.

“EMALS gives the Navy the flexibility to make adjustments based on aircraft weight and configuration to accommodate a wider range of aircraft, including lightweight unmanned aerial vehicles that cannot be launched with a steam catapult,” Kent said. “EMALS can be adjusted more optimally and rapidly than a steam catapult could accommodate, providing the Navy with the ability to increase sortie generation rate for our entire inventory of combat aircraft.”

Additional laboratory testing of the software glitches will be performed this year before control algorithms and fine-tuning can take place, Kent added.

“This will be followed by dead load launches, comparative steam catapult launches and aircraft launches at Lakehurst next fiscal year,” she said.

The fixes are designed to build upon how EMALS is engineered to adjust power and thrust depending upon the weight of the aircraft.  As a result, Navy officials say the system can be adjusted to accommodate the aircraft loaded with extra fuel tanks under the wings.

“EMALS will allow us to do the fine-tuning as necessary,” Kent said. “The resolution of this issue is straight-forward because the Navy will leverage this inherent capability of the system to tune the catapult forces for these wing tank configurations. There is no impact to ongoing shipboard installation or shipboard testing and this will not delay any CVN 78 milestones,” Kent said.

On the USS Ford, the below-deck EMALS equipment has been installed. This consists of a series of transformers and rectifiers designed to convert and store electrical power through a series of motor generators before brining power to the launch motors on the catapults, Moore explained.

"By having this electrical pulse come down, you are pulling the aircraft down to the catapult to launch it. You can dial in the precise weight of the aircraft. As you accelerate the aircraft down the catapult, you can accelerate it to the precise speed it needs to launch," Moore said.

Unlike steam catapults which use pressurized steam, a launch valve and a piston to catapult aircraft, EMALS uses a precisely determined amount of electrical energy. As a result, EMALS is designed to more smoothly launch aircraft while reducing stress and wear and tear on the airframes themselves, he added.

"By the time the aircraft gets to the catapult it is at the right speed. Minimizing stress on the airframe, over time, reduces maintenance," Moore added.

On the ship, EMALS will be engineered such that any of the ship's four catapults will be able to draw power from any one of three energy storage groups on the ship, he said.

-- Kris Osborn can be reached at Kris.Osborn@military.com

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