Modeling and Simulation: Aircraft Ailerons and the Mode Valve

Aircraft ailerons are important flight surfaces, providing pilots increased control during rolls to conduct safe changes in flight paths. Aileron functionality can be made possible through the use of Aircraft Hydraulic Actuation Systems (AHAS), those of which utilize a mix of technology to adjust surfaces in an efficient and reliable manner. One important element of aileron actuation systems is the mode valve, that of which we will discuss more in detail in this blog so that you may understand its role in simulation and modeling.

For the A320 aileron actuator model, development included the use of all components that would be necessary to simulate the active mode of the valve. This is when the actuator would utilize commands from the Actuator Control Electronic, and switches between modes would be carried out by the mode valve. For this specific model, the mode valve comes in the form of a two position valve with four ports, and it is situated between the actuator and servo valve with ports connected to servo valve and cylinder chambers. When the active mode is used, the mode valve will ensure a connection between the control ports of the servo valve and the cylinder ports so that nominal functioning of the system could be upheld. Meanwhile, the mode valve would isolate the servo valve control ports while using a damping orifice and anti-cavitation valves to connect the cylinder chambers during the stand-by mode.

As such control valves would not be able to work straight from the shelf for most needs, different applications would require custom created valves to ensure proper combinations. However, general directional control valves would provide four ports and two positions. The A320 aileron mode valve would also provide three possible paths out of the six normalized flow paths, those of which are the PA, BT, and AB paths. To control the mode valve, a unique solenoid valve would be needed to offer either supply or return pressure to the spool surface so that it may adjust between positions.

When simulating both aileron actuators on a control surface, scenarios are often run where the actuator initially acts in the active mode while switching to the damping mode after 0.5 seconds. When the actuator is faced with a sine antagonist load which should be handled by the hydraulic actuator in an active mode, the actuator is driven in the by-pass mode.

For aircraft such as the A320, it would be most realistic to have two actuators on a single control, though this is not always the case in situations where a variant mode valve would have a blocking mode. While the normal position consists of having cylinder chambers connected to their respective servo valve ports, the by-pass mode is when the cylinder chambers are connected without any relevant restriction. The blocked mode, meanwhile, does not permit any fluids to enter or leave by having both cylinder chambers isolated.

With a general understanding of how the mode valve can work for ailerons within modeling and simulation, one can better understand how such assemblies could be customized to fit the needs of various aircraft. Here at ASAP Fasteners, we can help you secure all of the actuation parts and aviation items you require to carry out your operations. Whether you are interested in items that are new, used, obsolete, or hard-to-find, we only stock parts from top global manufacturers that we trust to ensure the highest caliber products with each purchase. Take the time to explore our offerings, and utilize our online RFQ forms to quickly and easily request quotes for your comparisons. Additionally, you can also speak directly with our team members through phone or email, and we would be happy to assist you however we can! Let us serve as your strategic sourcing partner for all your operational needs when you get in touch with a team member today!


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