F-35C, Jet Blast Deflector (JBD) 테스트 완료 소식

 

美 해군이 차기 항모운용 전투기로 도입 예정인 Lockheed Martin F-35 Lightning II 의 Carrier Variant (CV) 형 F-35C 에

대한 Jet Blast Deflector (JBD) 시험이 최근 완료되었다는 소식과 함깨 관련 동영상과 사진들을 소개 합니다.

 

美 동부 New Jersey 州 Lakehurst 해군항공기지 (Joint Base McGuire-Dix-Lakehurst) 에서 실시된 JBD 시험에는 동부

Maryland 州 Patuxent River 해군항공기지에서 시험 비행에 투입되고 있는 F-35C CF-02 기가 6월 25일, Lakehurst 기지

로 이동하여 7월 8일까지 JBD 시험에 투입되었습니다.

 

JBD 는 항공모함 갑판에 설치된 것으로, 함재기 이륙시 발생되는 고온고압의 엔진 배기열이 이륙을 준비하는 다른 항공기

및 갑판 운용 요원들에게 피해가 가지 않도록 막아주는 일종의 반사판 기능을 하는 장치 입니다.

 

JBD 시험과 관련하여 금주에 발행된 AW&ST 의 상세한 기사 전문을 아래 소개 합니다.

 

지난 6월 25일 Lakehurst 기지로 이동하는 CF-02 기의 모습은 아래 링크를 참조하시면 됩니다.  --->

 

F-35C CF-02 arrives at Lakehurst for JBD test

 

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Not Just Hot Air

Jet-blast deflector tests set stage for carrier-based F-35 cat/trap work

Aviation Week & Space Technology, 07/18/2011

Author : Amy Butler

 

The multinational Joint Strike Fighter drew fire last year from all sides, including its international customers, the U.S. Congress and — most publicly — then-Defense Secretary Robert Gates owing to ballooning cost, delayed deliveries and unacceptably slow testing progress. Gates admonished prime contractor Lockheed Martin by withholding more than $600 million of award fee, fired the project’s two-star general officer, and slowed the development and production portions of the F-35, the largest single aviation program in Pentagon history. Seven months into 2011, Vice Adm. David Venlet has begun to express cautious optimism about the numerous steps needed to begin pilot training in the fall, progress toward ship-based trials of the F-35B short-takeoff-and-vertical-landing (Stovl) Marine Corps variant, and improvements in the overall pace of testing. These are key strides toward fielding the stealthy, single-engine F-35 in the U.S. and abroad, but years of work still lie ahead. Senior Pentagon Editor Amy Butler was given exclusive access to view a portion of the trials at Joint Base McGuire-Dix-Lakehurst, N.J., designed to validate models for the interface between the carrier-based F-35C and the jet-blast deflectors, which are used for catapult launches from ships.

 

Early results from testing the interface of the F-35C and ship-based jet-blast deflectors (JBDs) are easing the minds of experts in the field about how the new fighter will operate at sea.

 

Use of the F-35C with JBDs is only one of many pieces that must be validated prior to shipboard trials on a U.S. aircraft carrier in 2013, but the results so far are promising, says Kathy Donnelly, director of engineering for aircraft launch and recovery equipment at Lakehurst. “If you got asked a year ago [about this interface], we would have been much more pessimistic,” she told Aviation Week as the F-35C’s F135 engine roared only yards away during a test run.

 

Thus far, the testing is validating computer models that provide detailed predictions of how much heat a JBD must withstand to support routine operations of the F-35C at sea. JBDs are panels on the decks of aircraft carriers used to physically divert the hot exhaust as aircraft take off for missions. As an aircraft is prepared for flight, it rolls over the JBD into position on a catapult and the JBD is then hydraulically lifted at an angle behind it. The deflectors protect the deck from excessive heating while allowing for other aircraft to line up behind the launching aircraft; this supports rapid takeoffs, which are especially critical for surveillance and strike missions.

 

At first glance, JBDs do not look sophisticated; they appear as panels of concrete and metal. However, their design is based on precise engineering, says Donnelly. As new jet fighters are introduced into the fleet, engineers must validate the JBD design against the hot emissions of the new engines; modern fighter exhaust can reach temperatures of 2,300F or higher.

 

Water veins are designed in a precise pattern in the JBD to keep it relatively cool and to allow for more rapid aircraft launch tempos — in this case, simulating up to six successive launches. The most recent JBD design was crafted to support introduction of the Boeing F/A‑18E/F Super Hornet onto the decks of U.S. carriers. With its two General Electric F414 engines, this aircraft emits a different heat signature from that of the single Pratt & Whitney F135 on the F-35. While testing is aimed at exploring whether changes need to be made to the cooling-vein pattern on the JBD for F-35C operations, another goal is to determine if these deflectors can support both types of aircraft.

 

CF-02 was flown to Lakehurst June 25 for roughly two weeks of the F-35-only phase of JBD testing, which wrapped up July 8. The aircraft returned to NAS Patuxent River, Md., to join the carrier-version test fleet. CF-01 was originally slated to conduct the JBD testing, but its sister aircraft was substituted in at the last minute owing to a maintenance issue; CF-01 remains at NAS Patuxent River, Md. Alex Cadiz, a Navy chief aviation structural mechanic, says switching out the aircraft was seamless. CF-02 was outfitted with microphones on its vertical tails, as one of the goals of the trials is to examine the acoustics around the aircraft as it launches from a carrier. This will aid in crafting ear-protection devices for deck crews if new equipment is needed.

 

During the test runs, CF-02 is tethered; actual takeoffs and landings do not take place. The aircraft is planted at varying distances from the JBD and at different angles to simulate actual launch positions, says Tom Briggs, the flight-test engineer overseeing JBD testing. The trials are also designed to understand how common deck problems, such as a catapult malfunction, could affect the JBD; in one scenario, the launching aircraft blasted hot exhaust onto the JBD for a longer duration than a simple aircraft launch.

 

Lockheed Martin test pilot Dan Canin commanded different levels of engine power for various intervals. One example of a cycle is 10 sec. of standard military power, 30 sec. of limited afterburner and another 60 sec. at idle.

 

Ambient temperatures exceeded 90F with extremely high humidity during the JBD testing. This, however, is well within the normal operating temperatures on carrier decks. Briggs notes that carrier decks can reach 120F in some areas, such as the Mediterranean Sea.

 

Lakehurst is the only land-based facility of its kind in the world that is able to conduct detailed data collection of this sort, says Jonathan Myers, the lead JBD site engineer here. The JBD facility had been virtually dormant since the Super Hornet was tested during its development. As part of a year-long preparation of the site for JSF, officials procured six JBD “panels” and added instruments to collect data. Each aircraft carrier has three catapults operating with six-panel JBDs, and a single position — the outermost from the control tower — functions with four panels. The test configuration can be adjusted to collect readings on both types.

 

New for the F-35 testing was the installation of a 30,000-gal. water tank, designed to cool the fluid being fed into the JBD veins. While at sea, ships have an unlimited supply of cool ocean water to circulate through the JBD. But during Super Hornet tests, engineers were forced to stop and start the trials owing to problems with keeping the JBD water supply cool, Myers says.

 

Available instruments were also limited in number and function during the Super Hornet JBD trials. The instruments placed on intricate scaffolding behind the JBD have roughly doubled for the F-35 work. And Myers says these sensors are more sophisticated. During F/A-18 E/F trials, the sensors could measure only temperatures and wind in a single direction, says Tony Favorito, an aerospace engineer at Lakehurst. The sensors today can “measure anything coming at them” and take pressure readings from various directions. This is optimal because air behind the jet engine is “typically turbulent,” he notes. These readings are providing data on the air temperatures as well as helping to shape a more reliable picture of how air behind the F-35 will behave during actual launch operations at sea.

 

Even without the more extensive data provided by today’s sensor array, Super Hornet engineers gained valuable experience during JBD trials that led to a change in how the aircraft is launched. During testing, hot air was inadvertently recirculated into the air intake of the Super Hornet, prompting a “pop stall,” or hiccup in the airflow for the propulsion system. The result was a dangerous fireball coughing from the back of the Super Hornet, says Briggs.

 

The design fix was the creation of a limited afterburner setting for launch. Engineers crafted software such that the engine is at 122% of military power when a pilot sets it to afterburner. By the time the jet reaches the edge of the deck, the system automatically opens the throttle to full afterburner at 150% of power without intervention by the pilot, says Briggs.

 

Because of this lesson, the limited afterburner setting was designed into the F-35 in its infancy.

 

Thus far, Myers says, “I hate to say it [but] it has been very uneventful in terms of bad things happening” during testing. “We haven’t had any significant problems.”

 

Engineers are examining the data to figure out how, if at all, the pattern in the JBD’s cooling veins may need work. Additionally, engineers are paying close attention to whether side-panel cooling will be needed, especially on the second and fifth panels in the six-panel configuration, says Myers. The JBDs in the fleet today have side-panel cooling only on the middle two panels.

 

In the meantime, officials are shifting their focus to trials using a Super Hornet in JBD testing to revalidate older models. Ultimately, the goal is to conduct a final round of JBD tests with two aircraft, one emitting heat in front of the deflector and one behind. Officials have not yet decided if that will involve two F-35Cs or if there will be a mix of the Super Hornet and JSF.

 

Finally, the F-35C will begin catapult launch and arrested landing tests in early August. The goal is to conduct early trials at Lakehurst, shift to Patuxent River and then return to Lakehurst late in the month for a final round of trials using “degraded” catapults, says Myers. This would simulate when a launch system malfunctions or fails to produce the optimum amount of steam for takeoff.

 

As of June 30, Lockheed Martin officials say the F-35 program has accomplished 18% more flights than the planned 378 and 30% more test points than the planned 2,996. They break down by variant as follows:

 

• F-35A conventional version with 208 flights (180 planned).

• F-35B Stovl with 170 flights (138 planned).

• F-35C with 70 flights (60 planned).

 

Test-point statistics are:

 

• F-35A with 1,578 (1,533 planned).

• F-35B with 1,528 (1,072 planned).

• F-35C with 765 (391 planned).

 

The Stovl version has also executed 116 vertical landings to date.

 

 

  ⓒ Lockheed Martin

 

  ⓒ Lockheed Martin

 

  ⓒ Lockheed Martin

 

  ⓒ Lockheed Martin

 

  ⓒ US Navy