The Science & Technology of the MAGLift™ Rotor
Welcome to Quantum’s MAGLift™ Stabilizer System, truly one of the most unique stabilizing products available for both private, commercial, and military vessels today. This video provides an understanding of the Magnus effect, along with the various applications it has been applied to over the last century, including but not limited to Quantum’s series of underway and Zero Speed™ stabilizing products.
The Magnus effect, first investigated in 1883, is the generation of a force on a spherical or cylindrical body that’s rotating within a fluid or gas. There must be a relative motion between the fluid and the body to produce this force; meaning that the fluid must be moving over the body, or the body must be moving through the fluid. The direction of the force generated by the Magnus Effect is perpendicular to the direction of fluid movement.
Examining a scenario in which the fluid is moving horizontally, the force generated on the rotating body may either be in the up or down direction, depending on both the direction of fluid flow, and the body’s direction of rotation (referred to as the spin direction).
The magnitude of the force created is determined by the rotational speed of the rotor, called the spin speed. Though Quantum was the first to successfully apply the Magnus effect to the stabilization of ships, scientists and inventors have previously developed many methods of utilizing the Magnus effect.
The most famously known example is the Flettner rotor, in which a pair of rotors were vertically installed on the main deck of the ship, the Buckau, in 1925. With no propulsion other than the rotors, the ship could travel perpendicular to the wind direction, harnessing the Magnus effect. The ship successfully sailed across the Atlantic Ocean in 1926.
Another novel example of the Magnus effect being applied is the Plymouth AA 2004 rotor plane, built-in 1930. Featuring a spinning rotor on each side that replaced the typical airplane wing, the plane was reported to have successfully flown between New York and Connecticut.
Quantum’s system can utilize the Magnus effect to create stabilizing forces while a vessel is underway or stationary. To understand how the MAGLift™ Rotor can generate these forces, we must take a closer look at what’s happening to the fluid as it travels around the rotating rotor. We must compare the fluid flow path over the top of the rotor, as well as underneath.
When the rotor is deployed and spinning, fluid particles in the flow path above the rotor are propelled by the rotation and move faster as they move over the rotor. At the same time, the fluid particles in the bottom flow path are impeded, and their speed decreases. This results in the flow path above the rotor having a faster velocity than the flow path beneath it.
According to the Bernoulli Principle, an increase in fluid velocity is coupled with a decrease in fluid pressure. Thus, the flow path above the rotor, where the speed has increased, will experience a decrease in pressure, while the flow path beneath the rotor, where the speed has decreased, experiences an increase in pressure. This scenario produces a pressure differential across the body of the rotor, resulting in a force-directed from the high-pressure side of the rotor to the low-pressure side: in this case, upward.
A downward force would simultaneously be produced by the rotor on the opposite side of the vessel. The forces are transmitted to the ship, diminishing the unwanted rolling motions. The MAGLift™ Stabilizer System has the capability of retracting into a recessed pocket during inactivity, and extending beyond the hull envelope during operation, creating a longer lever arm for the force to act upon. As described earlier, the direction of the force generated by the Magnus effect is a function of the rotor’s spin direction, spin speed, and the direction of fluid flow.
While a vessel is underway, the water relative to the rotor travels in one constant direction. For underway operation, the rotor is deployed and maintains a position perpendicular to the hull. Quantum uses a bent access hydraulic piston motor to control the spin speed of the rotor, up to 500 rpm. To create both upward and downward forces to counteract a vessel’s natural roll, the spin direction of the rotor is alternated by changing the direction of oil flow through the hydraulic motor. This is achieved through precision control of a pressure differential valve.
When a vessel is stationary, a new problem arises. Without the vessel moving through the water, there is no relative movement between the rotor and the fluid. In Zero Speed™ mode, Quantum’s MAGLift™ system employs hydraulic cylinders to articulate a rack and pinion gear to swing the rotor back and forth 120 degrees through the water, effectively creating flow over the rotor.
The direction of fluid flow will now alternate each time the swing direction changes. In this scenario, the spin speed and spin direction of the rotor will remain constant, while the swing direction is manipulated to alternate the forces as needed to neutralize undesired rolling of the vessel.
Thanks again for joining us here at Quantum to learn about the compact, efficient, and extremely powerful system that is the MAGLift™ stabilizer.