In the 35th America’s Cup, ORACLE TEAM USA will compete in the AC50 race yacht, powered by the Parker Hannifin control system.
As the world leader in motion and control, Parker has combined its aerospace expertise and knowledge in flight controls along with its breadth of products to provide a lightweight, reliable and responsive hydraulic system.
With the majority of the yacht controls being fly-by-wire, the power and control to move the wing, sail and foils comes from the on-board hydraulics. This power is generated, stored and managed by the Parker products – designed and supported by the Parker team in Bermuda specifically for the America’s Cup. The control surfaces on the yacht include:
- Daggerboard Up/Down
- Daggerboard Pitch
- Daggerboard Cant
- Rudder Rake
- Jib Sheet
- Jib Lead
- Jib Cunningham
- Wing Camber
- Wing Twist
- Wing Inversion
- Utilities and plumbing to connect and control the system
As we move toward the America’s Cup race in 2017, we also celebrate the 100th anniversary of Parker – an achievement that brings with it extensive experience in hydraulic controls to give the team a competitive advantage to win!
As an innovation partner, Parker has provided engineering expertise in component and system controls to give the team an engineering solution to boat control.
As these boats have evolved, the design problems to solve become similar to those in aircraft. The hardware must be lightweight and reliable. The control logic must optimize the operating conditions to provide fast response and high accuracy to move the control surfaces of the boat and wing.
To achieve this, custom designs were created to meet the sailor needs using aerospace quality materials to provide high strength-to-weight characteristics with proven material properties including corrosion resistance for the demanding environment. Actuation for the control surfaces is optimized to minimize oil volume use while ensuring a capable load path for the high speed forces experienced and held in place with sealing solutions that prevent surface creep while minimizing friction.
The system incorporates aerospace type valving from Parker that is tuned within the electronics by engineers daily to continually optimize performance.
A change to the race rule in the 35th America’s Cup is the ability for the teams to use stored energy on the boat to move control surfaces. Because these boats now travel at such high speeds while flying above the water, safety becomes of critical importance. Were the sailors to lose the control of their foils’ angle-of-attack in the water, it could have catastrophic results. Therefore, the America’s Cup committee has allowed the use of Parker's fully composite, carbon hydraulic accumulators on the boat. As the sailors grind the pumps to create hydraulic energy, they can select to port some of this oil into the accumulators. This way, there is always a reliable source of hydraulic power.
The use of accumulators is only allowed for the foil pitch control and dagger board motion in and out of the water. As you view the boat sailing, watch as the dagger boards launch out from under the boat and power into the ocean. You will see how the team is able to maintain stable flight with the pitch control.
The accumulators used are the same in the boats of all teams. They are Parker composite accumulators fabricated specifically for the 35th America’s Cup campaign and designed to meet the harsh environmental conditions and performance needs of these race boats.
Manually generated power
Most of the controls on the boat are now fly-by-wire. Meaning that instead of manually pulling on lines and turning winches to move surfaces of the boat in maneuvers, the crew is able to push buttons and similar cockpit controls that electrically command the operation of the boat controls. This is made possible with the use of hydraulics. As the sailors grind on the pedestals, they are manually rotating hydraulic pumps which creates pressure and oil flow that can then be commanded to move the control surfaces when desired.
This makes for a difficult engineering problem as not only are the loads on the boat changing with varied wind and boat speeds, but the pressure generated by the sailors varies. The Parker controls must be responsive across the full spectrum of these operational parameters.
Efficiency is key
The use of manually generated power using hydraulics (which is relatively inefficient) draws a thorough detail in the design of the system. Efficiency becomes king. Any wasted energy diminishes the competitive edge of the system. Therefore, every detail is reviewed: pump displacements, operating pressures, leakage, valve types, actuator sizing, plumbing sizing, lengths and bends, etc. Detailed math modeling tools are used to ensure every aspect of the system provides the best weight to performance trade off.
With a maximum of four of the sailing crew generating hydraulic power at any time and each one producing about 300 Watts, the amount of energy available to control this high speed boat is about as much as it takes to make a small pot of coffee or toast over the course of a race.
Early in the system development, it was reviewed whether it would be more effective to use arm (grinding) or leg (cycling) for generating the necessary power. Although the results showed some potential for more power with legs, it was resolved that the crew would be able to better operate controls on the boat while grinding while being in a safer position in the event of a crash down as well as keeping their legs from getting weak when needed for traversing the boat during maneuvers.
Closed loop controls
Another change to the rule in the 35th America’s Cup includes the ability to use closed loop control. This means that teams can use an electrical sensor to monitor the position of the actuators that move the boat control surfaces and use that information to control where the actuator moves to at any time.
At the speeds that the boat is flying above water, the control of the foil pitch is critical for responsiveness, accuracy and safety. For monitoring actuator position, the Parker Intellinder system is used. This is an optical sensor that is mounted to the actuator body and reads the piston position via bar code striping. By using the on-board electronics to monitor the position of the Parker actuators from the Intellinder position sensors, the sailors can command the foils to move to a position and the closed loop control algorithms position the board exactly as desired in minimal time without overshoot. The Intellinder position sensor has proved to be a reliable, lightweight and accurate means of accomplishing this task.
Although every function on the boat must be initiated by the sailors on board, this closed loop control is allowed for the rudder and board pitch control.
Watch this video about the Parker Intellinder System
This post was contributed by Stuart Meurer, Parker project manager on the ORACLE TEAM USA yacht, Parker Aerospace.