Aircraft Landing System, Part 2

Seahawk Helicopter landing with RAST System

Comrade Misfit denounced my big idea as old hat, and suggested I look up the RAST system, so I did. The Navy stole my idea before I even thought of it. Durn their hides anyhoo. Works with the Navy's SH-60B helicopter, an eight ton behemoth.

From Global Security's article on the SH-60B Seahawk:

The Seahawk helicopter differs from other helicopters in the Navy inventory in that, the Recovery Assist, Secure and Traverse (RAST) landing system is used. This system allows for recovery of aircraft in high sea states (6 degrees pitch, and 15 degrees roll). During RAST operations, the helicopter lowers a messenger cable that is connected to the ship’s haul down cable. The messenger cable is raised and locked into the helicopter’s RAST probe. Four thousand PSI of force is applied to the haul down cable which guides the probe into the locking beams of the Rapid Securing Device (RSD). The RSD also serves as the motive force to traverse the helicopter into and out of the hanger. The main rotor blades and tail pylon can be folded for storage. Movement of the SH-60B by hand is prohibited except during emergencies due to the 15,500 pound empty weight. In addition, the helicopter can operate from non-RAST equipped combatants and a variety of other naval ships.

On a pitching ship, where the flight (or landing) deck is moving up and down, there is going to be considerable stress on the chopper. Every time the deck goes up, the rotors need to producing enough lift to keep the line taught, and every time the deck goes down the chopper is going to be dragged down through the air.

Curtis Wright builds the system. I only found one video of it in use. It looks like a dry run in good weather and it's hard to tell if it is even doing anything.

Update November 26, 2010: An anonymous source provided me with a more accurate description of how this thing works. The cable doesn't actually pull the helicopter down. It acts more like a guide to ensure that the probe on the bottom of the chopper is caught by the trap on the deck on the ship (the life raft looking thing sitting on the deck directly underneath the chopper). The shipboard winch reels and unreels the cable to maintain constant tension. So the force of impact when the chopper actually touches down is still in the hands of the pilot and depends on gauging the distance from the deck, how fast it is moving and in what direction. I imagine that's were the cable and all it's associated equipment comes in. A very tricky bit of flying in any case. You also have the added terror of being chained to the boat, though I imagine there is a quick release for emergencies.

Originally posted November 20, 2010.

Update February 2017 replaced missing picture.