Self Boarding

For decades, one of the requirements for Navy carrier-based aircraft was self-boarding. Ladders were anathema on a crowded, windy carrier deck full of whirling propellers and jet intakes. This became more and more difficult to accommodate with jets, particularly those with long nose gears to provide a high angle of attack for takeoff and landing. In the case of the XF3H Demon, for example, McDonnell expected the pilot to scale the nose landing gear until he could reach the hand/foot holds at the bottom of the black stripes and put his right foot on the black non-slip area on the nose gear door. After that, the ascent was fairly straight forward.

This concept was arguably more challenging than the production version shown in a prior post (http://thanlont.blogspot.com/2008/05/i-had-hoped-to-find-picture-like-this.html), which required the pilot to clamber up onto the wing from its trailing edge, walk up to the leading edge, and then traverse the fuselage from there to the cockpit by stepping on small pegs that extended out when the canopy was opened. Detachable ladders soon became acceptable and self-boarding was waived for the A4D Skyhawk and the production F4D Skyray.

Mark Nankivil provided the illustration from the XF3H Flight Manual.

For more on self-boarding, see http://thanlont.blogspot.com/2015/10/carrier-based-airplane-self-boarding.html

The General Purpose Fighter

One of the mission specifications during the early years of carrier-based jets was general purpose fighter. This was essentially a fighter being used as an attack aircraft. The McDonnell F3H Demon, originally intended to be a dedicated interceptor as an alternate to the Douglas F4D Skyray, was redirected to be also be an alternate to the Grumman F10F Jaguar with a general purpose fighter capability. This F3H-2N, BuNo 137029, is loaded for display purposes as a general purpose fighter with six small, box-tail, general-purpose bombs on the wings and two 1,000-lb low drag bombs on the belly. The picture was taken in May 1957 at Lambert Field in St. Louis by Aviation Week's Pete Bulban. (The aircraft in the background is McDonnell's XV-1 compound helicopter.)

Before Steam Catapults

In the early 1950s, the weight and end speed requirements of new jet airplanes were at the upper limits of the capability of existing hydraulic catapults. One technique explored to get the maximum benefit out of what was available was the tail-down launch at maximum angle of attack.

The F7U Cutlass was already positioned at an exaggerated nose-up attitude when on its wheels but this catapult lash-up made it more so. The holdback fitting, main gear strut extension and position (it was angled forward for takeoff), and the little "grocery-cart" wheels added under the vertical fins allowed the catapult crew to tension the airplane at the steepest possible angle. You'll note that the tires are notably flattened by the forces involved.

However, the shore-based trials at Patuxent River demonstrated that there was no benefit relative to a more conventional hookup to the catapult: The angle of attack off the bow was greater but the end speed less, so the lift attained at the end of the catapult stroke was about the same. The extra time required to force the airplane into this position for launch was also a drawback. In any event and fortunately for Naval aviation,  Colin Campbell Mitchell's timely development of the steam catapult allowed a significant increase in the upper weight and end speed limits.

Waving Them Aboard

Pictured is an Loening OL-8 landing aboard Lexington, CV-2, with the Landing Signal Officer (LSO) giving the Roger signal, for the pilot being at the right airspeed and altitude and lined up correctly, and about to give the cut for descent and touchdown.

The LSO was one of the earliest innovations in landing aircraft aboard carriers. He stood on the port side of the deck near the ramp and by using a standard set of signals, assisted the pilot in touching down among the arresting wires at minimum speed and a low rate of descent.

For some reason, the Royal and U.S. Navies developed slightly different techniques for landing aboard. Royal Navy pilots were taught a descending approach and the LSO signal for the pilot being above the correct approach path was lowered paddles, meaning descend. The U.S. pilot made a low, flat approach and the LSO signal for being too high was raised paddles. (The signals for lineup were the same since the U.S. Navy signals for correcting height and lineup were inconsistent, like tilting down to the pilot's left to ask for tightening the turn and raising the paddles up for descend.) Fortunately, there was very little cross decking between the services during the war.

In 1948, the Royal Navy elected to change to the U.S. Navy LSO signals and shortly after that, adopted the low, flat approach as well. A reduction in accident rate resulted although it's not clear why. The British subsequently developed the mirror landing approach aid. The mechanics of the mirror concept combined the original British descending approach and the American signal for being too high, with the ball on the mirror going up when the airplane was above the desired "glide" slope.

Following the transition to the mirror-guided approach, the LSO role was initially downgraded to more of an administrative one in the belief that the pilot no longer needed his guidance. It was soon established that the LSO could detect a trend quicker than the pilot and moreover, had a better sense of deck motion, which affected the validity of the mirror display even though it was gyro stabilized. As a result, the LSO was again established as the controlling authority for the approach.

The Way It Was

The bridle is already positioned on the catapult shuttle and two green shirts are waiting for the F2H to taxi forward into position for hookup. The catapult hooks are located on each side of the fuselage just aft of the engine inlets at the juncture of the fuselage and engine nacelle. The two green shirts lying on the deck have the holdback pendant. The Banshee taxis over them to be in position for the hookup on the aft fuselage. After the green shirts connect the bridle and holdback to the aircraft, they will stay there until the shuttle is tensioned to insure that the whole lash up stays in position, as shown here on an A3J-1.

Making Life Easier for the Green Shirts

Up until the early 1960s, catapult launches were accomplished by connecting the aircraft to the catapult shuttle with a heavy cable, called a pendant or a bridle depending on the hookup configuration. A separate hookup held the aircraft from moving even under full power until the catapult fired and a weak link in the holdback failed with the increase in pull.

This was hard, dangerous work. The cables were heavy and the hookup point on the aircraft generally uncomfortably close to the jet engine inlets or the propellers. The holdback connection was under the aft fuselage, just forward of the jet engine exhaust, a dark, dirty, noisy place, usually requiring a very low squat to access the fuselage hookup point.

The replacement was the addition of both the catapult and holdback hookups onto the nose landing gear. Grumman developed the concept and introduced it with A-6 Intruder and the E-2 Hawkeye. The launch bar was located on the front of the nose gear strut and could be raised and lowered by the pilot; the holdback connection was on the aft side of the nose gear strut.

The pilot simply taxied forward onto the catapult hook up point and lowered the launch bar. The green shirts then attached the holdback bar (color coded for each aircraft type) to the aircraft and the deck and signaled for the shuttle to be moved aft until the front end of the launch bar was positioned in the cavity at the front of the shuttle. The shuttle was then moved forward to fully engage the launch bar and establish tension. Once the pilot was ready; full takeoff thrust applied; and final checking accomplished, the catapult was fired; the holdback connection released (leaving the holdback bar on the deck); and the aircraft was on its way.

The two different launch hookups coexisted for a time, since retrofit of the concept would have required extensive structural modification to the aircraft. Eventually, however, the last of the pendant/bridle-launched aircraft was retired.

If You Can Read This...

Ramp strikes occur when a pilot gets too low on an approach to the carrier and hits the round-down at the aft end of the deck. Many end very badly unless it is just a hook slap. Rare now, they occurred more frequently before the advent of the angled deck as pilots were concerned about landing long on an axial deck and crashing into the barriers that protected the people and airplanes forward. The landing signal officer will call "power" if the approaching airplane begins to sink below the proper glide path.

Several years ago, I spent a day and a night as a guest aboard the carrier Eisenhower off Norfolk while it was being used for carrier qualifications by F-18 Hornet pilots. Day landings were straight forward, with few bolters, fewer waveoffs, and an occasional desultory call by the Landing Signal Officer for "power". Night landings were entirely different. Frequent waveoffs and bolters, and often the call for "Power, Power!, POWER!!" After one of these, the LSO went so far as to call the pilot on his downwind and say, "When I say Power, you add Power. Don't second-guess me. Do it again and I'm sending you to the beach."

If you click on the picture*, you should be able to read the warning on the ramp...

*USN 090415-N-7241L-239 by Specialist second class Nathan Laird