U.S. Navy Takes Delivery of 400th F/A-18E/F Super Hornet

[razgriz19]

U.S. Navy Tests Biofuel-Powered 'Green Hornet'
UNITED STATES - 22 APRIL 2010

WASHINGTON -- The U.S. Navy celebrated Earth Day April 22 by showcasing a flight test of the "Green Hornet," an F/A-18 Super Hornet multirole fighter jet powered by a biofuel blend.

The test, conducted at Naval Air Station Patuxent River, Md., drew hundreds of onlookers, including Secretary of the Navy Ray Mabus, who has made the exploration and adoption of alternative fuels a priority for the Navy and Marine Corps.

Mabus observed the flight and tracked its data from a Project Engineering Station at the air station's Atlantic Test Range. After the jet landed, he met the pilot, Lt. Cmdr. Tom Weaver, of Billerica, Mass.

"The alternative fuels test program is a significant milestone in the certification and ultimate operational use of biofuels by the Navy and Marine Corps," said Mabus. It's important to emphasize, especially on Earth Day, the Navy's commitment to reducing dependence on foreign oil as well as safeguarding our environment. Our Navy, alongside industry, the other services and federal agency partners, will continue to be an early adopter of alternative energy sources."

The Green Hornet runs on a 50/50 blend of conventional jet fuel and a biofuel that comes from camelina, a hardy U.S.-grown plant that can thrive even in difficult soil.

The Defense Energy Support Center, which oversees procurement of biofuel for the Navy, recently awarded a $2.7 million contract to Sustainable Oils of Seattle and Bozeman, Mont., for 40,000 gallons of camelina-based fuel. The Navy's ultimate goal is to develop protocols to certify alternative fuels for use in its aircraft and ships.
"The aircraft flew exactly as we expected- no surprises," said Weaver, F/A-18 project officer for Air Test and Evaluation Squadron (VX) 23 and pilot for the Earth Day flight test. "The fuel works so well, all I needed to do was just fly the plane."

"Our mission today and for the rest of the flight tests is to confirm that the fuel makes no difference in performance across the Super Hornet's entire flight envelope, from subsonic to supersonic operations," said Mark Swierczek, Naval Air Systems Command propulsion flight test engineer. "Preliminary results show there was no difference in engine ops attributable to the biofuel. Engine performance is normal and as expected."

The Navy Fuels Lab at Patuxent River is developing certification standards for a variety of renewable, alternative fuel sources.

"These flight tests are part of an extensive test and evaluation process that started last fall," said Rick Kamin, the Navy's Fuels team lead. "The fuel's chemical and physical properties were first analyzed in the lab, followed by component and engine performance testing - and now in a series of flight tests covering the entire flight envelope of the Super Hornet – including supersonic operations."

According to Kamin, final approval and certification for the camelina-based biofuel could take an additional six to nine months after flight test April 22. The Earth Day flight test is one of 15 planned test flights requiring approximately 23 flight-hours to complete, starting in mid-April 2010 and completing by mid-June 2010. The Earth Day flight lasted about 45 minutes.

The Green Hornet biofuel program is the first aviation test program to test and evaluate the performance of a 50/50 biofuel blend in supersonic (above mach 1) operations – a critical test point to successfully clear the F/A-18 E/F for biofuel operations through its entire flight envelope. Once successfully demonstrated on the F/A-18 F414 engine, the Navy will expand its certification efforts to other Navy and Marine Corps aircraft and Navy tactical systems.

PATUXENT RIVER, Md. (April 22, 2010) The U.S. Navy celebrates Earth Day by showcasing a supersonic flight test of the "Green Hornet," an F/A-18 Super Hornet strike fighter jet powered by a 50/50 biofuel blend. The test, conducted at Naval Air Station Patuxent River, Md., drew hundreds of onlookers that included Secretary of the Navy Ray Mabus, who has made research, development, and increased use of alternative fuels a priority for the Department of the Navy.

the landing gear is a bit wierd..

 

[gambit]

the landing gear is a bit wierd..

The F-18's main landing gear is one of the more complex, if not THE most complex landing gear design on such a small aircraft.

First...Understand that the YF-17 was originally for the USAF...

Northrop YF-17 - Wikipedia, the free encyclopedia

Although it lost the LWF competition to the F-16, the YF-17 was selected for the new VFAX specification. In enlarged form, the F/A-18 Hornet was adopted by the United States Navy and United States Marine Corps to replace the A-7 Corsair II and F-4 Phantom II, complementing the more expensive F-14 Tomcat.[1] This design, conceived as a small and lightweight fighter, would ironically be scaled up to the F/A-18E/F Super Hornet, which is similar in size to the original F-15. The Super Hornet has replaced the F-14 in USN inventory, and performs all jet combat aircraft roles in the Navy from attack to fighter, tanker and electronic warfare.

For carrier operation, the Navy prefer to have the landing gear of its fighters, or similar class aircrafts, be further back as Navy aircraft usually land with slightly higher angle-of-attack than Air Force aircrafts. Not much higher, but still higher. This is to help cushion the harder landing impact and because of the slightly higher AoA, this more rearward position would prevent the tail from hitting the deck.

But when the Navy picked up the YF-17, any redesign of the main landing gear system to meet Navy preferences would require redesign of other major parts of the aircraft as well. Not impossible but very difficult and costly. The decision was to leave the main landing gear position as originally designed, but to install a bending structure, which was called a 'knee', to position the wheel itself further back to where the Navy prefers.

Here is how this repositioning ended up looking...

So for the F-18, do not confuse the main gear strut with the main gear wheel/tire locations. As seen above, they are some distance (rearward) apart.

So AFTER the decision to leave the main gear strut in its original location in the fuselage, the Sparrow missile mount points, also seen above, complicated the matter even further. Weapons mount points, bombs and missiles, are not arbitrary and is its own can of worms. Suffice for this explanation is that with the desire to mount the new Sparrow missile, with its head-on attack capability compared to rear chase only for the Sidewinder, a redesign of the main gear, from below the main strut, was necessary.

MD/Northrop engineers originally wanted to leave the Sparrow off the aircraft altogether as at that time the missile was still too new and did not have a good testing record. But the Pentagon decided that even if the Sparrow does have a spotty record at head-on radar guidance, the fact that an air adversary now have a chance of being killed in such a scenario was worth the redesign. Robert H Thompson, who worked for Admiral William Houser...

William D. Houser - Wikipedia, the free encyclopedia

...And Thompson himself was a Top Gun instructor, compared the new Sparrow to that of a drunk armed with a pistol. Thompson argued that it did not matter much that the new Sparrow was not as good at such a head-on scenario, like how it was unimportant that the drunk would not be a good shot, the fact that the drunk is armed is enough to compel you to alter your tactics. MD/Northrop was told that either their engineers come up with a new main landing gear system that would withstand the harsh landing, prevent the tail from scraping the deck and accommodate the Sparrow misisle...Or lose the contract.

The result was one of the more, if not the most, complex landing gear system to date on such a small aircraft. At weight-off-wheels, the gear simply dangle at that 'weird' angle, then the 'knee' bends and rotates, then the wheel twists, then the entire assembly folds.

890 F2d 698 Kleemann Ss v. McDonnell Douglas Corporation Kleemann | Open Jurist

On December 3, 1985, Captain Henry M. Kleemann, a U.S. Navy pilot, was killed when his F/A-18 aircraft went out of control during landing, left the runway, and overturned. Defendant McDonnell Douglas Corporation (MDC) had designed the F/A-18 for the Navy. The Navy concluded that Captain Kleemann's accident was caused, in part, by failure of the planing link assembly on the main landing gear. The planing link assembly was designed to assist folding and unfolding the wheel assemblies into and from the wheel well and to lock the wheels appropriately for takeoff and landing. It allows the wheels to "deplane," or move out of line with the direction of the aircraft, during retraction and extension of the landing gear.

The hypothesis was that after take-off, the wheels are usually still spinning, once they are fully nested inside the wheel wells, the brakes are automatically applied to stop them from spinning. This is applicable to all aircrafts. For the F-18, that particular mishap occurred when the brake was applied, the spinning wheel stopped suddenly enough to bend the left link. When Kleeman arrived at Point Mugu, the left main gear failed to properly aligned so when he landed, the F-18 veered sharply left, ran off the runway into the rain soaked grass, and flipped upside down.

Note this paragraph in the above lawsuit...

For example, the main landing gear at issue here had to absorb extremely high amounts of energy generated upon landing on a carrier. On the other hand, stowage of the gears could not interfere with external weapon storage. These competing concerns required a unique "levered gear" design to provide adequate distance between the extended right and left main landing gears and thereby ensure stability of the aircraft upon landing. The design, developed by MDC and approved by the Navy, employed a planing link assembly to deplane the wheels during retraction and extension of the landing gear.

The sad irony here is that if this mishap occurred on an actual carrier landing, the arrest cable would most likely prevented the aircraft from flipping upside down as his stop would be far shorter and quicker than a conventional runway landing. If the captain was alerted in the cockpit that his left gear was not properly aligned, he could have called a 'trap', Point Mugu would create that carrier landing situation -- raise the arrest cable located at end-of-runway.

Hope this raise awareness to interested readers as to how complex designing an aircraft, let alone a warfighter, can be -- from just the landing gear system.

 

[gowthamraj]

@gambit. . . Is export version also have the same landing gear for f18 that for AF not AC

 

[gambit]

@gambit. . . Is export version also have the same landing gear for f18 that for AF not AC

As far as I know, all F-18s, including the current evolution, has the same design. Individual components have been upgraded but the overall design is still the same.