A top view of an improved Nimitz-class (CVN-68) nuclear-powered aircraft carrier. JACK RYAN ENTERPRISES, LTD., BY LAURA DENINNO

If you move aft from the bow down the 'Street,' you walk between the two bow catapults, each as long as an American football field. And there is a similar catapult arrangement on the landing 'angle' on the port side. Most of the machinery for each C13 Mod. 1 catapult is concealed under the flight deck: two slotted cylinders in a long steel trough, each with a narrow gap along the top. Overlapping synthetic rubber flangles cover and seal the gaps. In each cylinder is a piston, with a lug projecting through the sealing strips on top. Each of these lugs leads to a small crablike fixture called a 'shuttle,' which is up on the flight deck.

When an aircraft is ready to launch, it is maneuvered into position under the guidance of a plane handler. When the nosewheel is just behind the shuttle, a metal attachment on the gear strut, called a towbar, is lowered into a slot on the shuttle. Meanwhile, the Jet Blast Deflector (JBD) just aft of the plane is raised, and another mechanical arm is attached to the rear of the nose gear strut with a device called a 'holdback.'[37] This allows the aircraft to run its engines up to full power, far beyond the ability of the plane's brakes to keep it on the deck. In this way, the bird will have a considerable forward thrust even before it starts moving. Each aircraft type in the wing has its own special color-coded holdback, to prevent them from being used mistakenly on the wrong bird. The exceptions are the F-14 Tomcat and F/ A-18 Hornet, which have permanent holdback devices built into their nosewheelgear struts.

The nose gear of an F/A-18C Hornet on the #1 Catapult of the USS George Washington (CVN-73). The forward towbar is linked to the catapult shuttle, and the holdback device is in position. JOHN D. GRESHAM

Once the aircraft is properly hooked up by one of the green-shirted catapult crewmen, another 'green shirt' holds up a chalkboard with the plane's expected takeoff weight written on it for the pilot and catapult officer (down in the catapult control pod) to see. If both agree that the number is correct (confirmed by hand signals), then the catapult officer (known as the 'shooter') begins to fill the twin pistons with a pressurized charge of saturated steam from the ship's reactor plant.[38] The steam pressure is carefully regulated to match the takeoff weight of the aircraft, the speed of the wind over the deck (this is the natural wind speed plus the speed of the ship), and other factors like heat, air pressure/density, and humidity. This has to be very precise. Too much pressure will rip the nosewheel gear out of the plane, while too little will cause a 'cold shot.' In a cold shot, the aircraft runs down the deck and never reaches takeoff speed; the catapult then hurls it into the water ahead of the onrushing carrier.[39] At best, the crew will eject and the aircraft will be lost. At worst, both the aircraft and flight crew will be lost. As might be imagined, catapult officers (who are themselves veteran carrier aviators) take this highly responsible job quite seriously.

Once the pressure is at the desired level, there is a final check of the aircraft by the green shirts. If all appears to be at readiness, the catapult officer signals this to the pilot. The pilot selects the proper engine setting (usually maximum power or afterburner), snaps a salute back to the catapult officer in the pod, and braces for what is about to come. At that point, the catapult 'shooter' hits a button in the control pod, and the twin cylinders are released. This snaps the holdback and throws the aircraft down the catapult track. The pilot/crew is hit with several times the force of gravity (what pilots call 'G' forces), and their eyes are driven back into their sockets. Approximately one hundred yards/ninety meters and two seconds later, the towbar pops out of the shuttle, and the aircraft is on its own. Having achieved flying speed (usually around 150 knots), the pilot has now gained control of the airplane (that is, he or she can actually fly it).

Back on deck, a cable and pulley system retracts the shuttle to its start position, and the cycle repeats. A well-trained crew can complete this process in less than two minutes. A normal launch sequence using all four catapults can put an airplane into the air every twenty to thirty seconds. This means that launch events for several dozen aircraft can take less than fifteen minutes from start to finish. However, since the aircraft just launched will be back to land in only a couple of hours, the timing of what gets done next can be critical.

Configuring the flight deck for a landing 'event' requires that the deck be 'respotted,' with as many aircraft as possible moved forward. In most cases, these are parked on Rows 1 and 2, so that the 'angle' will be clear for returning aircraft; and this means that Catapults 1 and 2 are now blocked and unavailable for use. While it is theoretically possible to launch aircraft during landing operations, this is rarely done. To do so would require much of the air wing to be struck below to the hangar deck, a time-consuming and tiring exercise for the deck crews. In fact, carrier captains like to use the aircraft elevators as little as possible, since these constitute part of the flight deck and parking area for aircraft when they are in the 'up' position. It's hard to find anything more precious to a carrier skipper than flight deck space, and even the four and a half acres on a Nimitz- class flattop seems small when filled with airplanes, ordnance, equipment, and people.

The flight deck can not only get crowded, it can easily become dangerous. For this reason aircraft that are not actually taking off or landing are parked and chained down as quickly as possible. Chaining down is also necessary because a slight list on a slick deck can send an aircraft sliding around like a rogue hockey puck on an ice rink. In fact, almost everything on deck is chained down when it is not in use, including the low-rise firefighting and aircraft tractor vehicles. Normally, as soon as an aircraft is shut down and parked, a crew of strong-backed young blue shirts moves in to attach tie-down chains to some of the thousands of tie-down points imbedded in the plating of the flight deck.

On the port side aft is a sponson holding what is called the 'Lens.' This is a stabilized (against the motion of the ship) system of lights and directional lenses, designed to provide approaching pilots with a visual glide path down to the deck. If an approaching aircraft has the proper attitude and sink rate, then the pilot sees an amber light-or 'meatball'-from the system. If the pilot can keep the 'ball' centered (with a row of green lights) all the way down (any offset from the proper attitude shows the pilot a row of 'red' lights), then it should put him down in the perfect spot for a landing on the deck aft.

Once the flight deck has been respotted for the coming landing event, and the ship has once again come into the wind, things again get exciting. Modern carrier aircraft are too heavy and their stall speeds are too high to possibly land in the roughly 500 feet/152 meters of space on the flight deck. In fact, the only way to get a high- performance airplane onto a carrier deck is to literally fly it to a 'controlled' crash, and stop it forcibly before it falls into the sea. The lens system and other special landing instruments (some aircraft even have an automatic landing system) are useful aids, but pilots usually need additional help. This formidable task is the job of a lot of very special equipment and is overseen by the Landing Signals Officers (LSOs). Back in the old days of propeller-driven planes and the early jets, LSOs were the only landing aid for pilots. They did their job with nothing more than a pair of lighted paddles (to show the pilots their landing attitude) and a few hand signals. LSOs today do their job from a small platform on the port side aft, and it is there that we now will go to get a perspective on the fine art of a carrier landing.

Landing a carrier aircraft starts in the aircraft cockpit, when the pilot makes the break into the ship's landing pattern. The pattern itself is controlled by the Carrier Air Traffic Control Center (CATCC) located one level down from the flight deck. The CATCC is a miniature of what you would find at any major airport, and it functions in exactly the same way. The controller's job is to 'stack' the aircraft, prioritize them into an oval-shaped pattern about a mile wide and four miles long around the port side of the carrier, and 'stagger' them, so the LSO has the necessary time to bring each aboard. (They can land an aircraft about every thirty seconds under good conditions.) The aircraft in the pattern are prioritized by their 'fuel state,' a polite way of saying that the first planes to be brought aboard are the ones that are about to fall into the ocean from fuel starvation. Just to be sure this does not happen, the carrier usually has an airborne tanker overhead during flight operations to refuel airplanes too close to the Empty point on their fuel gauges.

When the landing event has been properly organized, the 'Lens' is turned on, and the first pilot in the pattern makes the 'break' out of the pattern to line up on the stern of the carrier. During the 'downwind' leg of the pattern, the pilot drops the plane's landing gear, tailhook, and flaps, makes sure the radio is set up on the LSO frequency, and turns left toward the boat. Assuming all this has been done properly, the aircraft should start its final approach at eight hundred feet altitude, about three-quarters of a mile from the stern of the carrier, and just

Добавить отзыв
ВСЕ ОТЗЫВЫ О КНИГЕ В ИЗБРАННОЕ

0

Вы можете отметить интересные вам фрагменты текста, которые будут доступны по уникальной ссылке в адресной строке браузера.

Отметить Добавить цитату