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US Navy aircraft carriers
Aircraft carriers are the centerpiece of America’s Naval forces – the most adaptable and survivable airfields in the world.
US Navy flat tops support and operate aircraft that engage in attacks on airborne, afloat and ashore targets that threaten free use of the sea and engage in sustained power projection operations in support of US and coalition forces. Aircraft carriers must be able to launch these aircraft in such a small space. With so much chaos in such a small area, engineers have had to design catapults, simple yet effective devices to help manage the process.
Cat shot
Getting air moving over the deck is important, but the primary takeoff assistance comes from the carrier’s four catapults, which get the planes up to high speeds in a very short distance. Each catapult consists of two pistons that sit inside two parallel cylinders, each about as long as a football field, positioned under the deck. According to How Stuff Works, the pistons each have a metal lug on their tip, which protrudes through a narrow gap along the top of each cylinder. The two lugs extend through rubber flanges, which seal the cylinders, and through a gap in the flight deck, where they attach to a small shuttle.
A catapult shot (or cat shot) usually generates up to 4 Gs and the airspeed will go from zero to 160mph in just two seconds.
Green shirts showing pilots gross weight of their aircraft
What is the green shirt (actually green shirts are responsible for Catapult and Arresting Gear aboard an aircraft carrier) in the photo of this post showing to the F/A-18 Super Hornet pilot before catapult launch?
‘He is showing to the pilot what he believes is the gross weight of the aircraft on the catapult. This weight is extremely important. It needs to be known for proper setting of the catapult,’ says John Chesire, former Naval Aviator, on Quora.
‘Usually, the planned or estimated gross weight before taxiing will be written in chalk on the aircraft’s nose-gear door. The guy in green will show this weight to the pilot for confirmation. If the pilot agrees with that weight displayed, he will give a “thumbs up”. If the pilot knows that weight shown to him is incorrect, he will signal with his hands to raise or lower the displayed weight until it matches the correct gross weight. He then will give a thumbs up; the catapult crew will set in the proper adjustments for that weight, and the aircraft will soon be shot off the deck.’
Chesire concludes;
‘This occurs on every flight and launch.’
Photo credit: U.S. Navy
