Engine management

 

Engine management represents the power related aspect of the handling of the liftoplane. The action of this management overlaps with the biangular handling in two aspects. At first, a change in the rotation speed of the rotors modifies the airflow condition on the wings and is reflected in a change in the PGS-state at fixed values of the biangular handling. At second, a change in the rotation moment of the rotors modifies the entire rotation moment of the aircraft and is reflected in a change in the state of the "stream following" system used to maintain a steady reference frame required for the biangular handling. In this regard, this management reflects these two aspects in construction and functionality. The diagram below represents the functionality of this management.

Engine management diagram

The rotor of each side is connected to the corresponding electric engine by a central shaft of the light gray color. These shafts are connected each other, so there is a common powering shaft. This provides a sufficient level of redundancy. So, the liftoplane can fly on one engine. Each engine has a power circuit, which provides a bidirectional exchanging of the power between the engine and the accumulators in a high range of the rotation speeds. Winding Speed (WS) is used as a primary representation of this rotation speed. This winding speed is defined as the linear speed at a certain radius of this combined rotor. This radius is equal to the radius of the pivot positions of all wings. See also the diagram for biangular handling.

 

The winding speed has two representations with respect to time. At first, there is an instantaneous winding speed, which I call the actual winding speed (WSA). At second, there is an anticipated winding speed, which the rotor is required to have finally as a result of this management. I call this speed the target winding speed (WST). For safety reasons this WST should be tied to a mechanical handling domain. This tying provides stability by having a state value whose rate of change is limited. An angular encoder depicted in the dark yellow color is used for this. This encoder is rotationally connected to a WST trimmer of the green color for precise control.

 

There is a significant rotation moment applied to the rotor for any particular winding speed. The direction (i.e. sign) of this moment does not depend on the direction of the winding speed itself. This feature is originated from the "flying elevator" concept and reflects the same feature for a force acting on an imaginable "lift" with a variable direction of its movement. On the other hand, a variation of the winding speed imposes a respective variation of the rotation moment with a change in sign. A Moment Ratio (MR) is used as a primary representation of the rotation moment applied to the entire aircraft. This moment ratio is defined as the ratio of an equivalent rotation force acting in the pivot position of the forward wing that creates the equal rotation moment, to the weight force of the entire aircraft. This general moment ratio has two particular components. The first component represents a moment rising from a reaction force from the rotor of the engine to its stator through the magnetic force interaction. By that way, the rotation moment of the rotor of the engine aggregates all external (in the respect rotor-stator) rotation moments. So, the first component can be called the External Moment Ratio (EMR). The remaining second component can be called the Internal Moment Ratio (IMR), and it represents the moment arising from the forces induced by the wings on the mechanical elements of steering the pitches of such wings. The sum of the aerodynamic moments of all the wings in with respect to their pivots creates this IMR, and it is relatively small in comparison to the EMR.

 

Due to the matter exposed at the beginning of the previous paragraph, it is clear that EMR also has two components. The first component represents the rotation moment originated from aerodynamic forces compensating the entire weight of the aircraft. The second component represents inertia forces originated from changing the winding speed. The latter component can be significantly high during high acceleration or deceleration of the rotors, leading to adverse effects. So, such cases should be avoided. Using the trimmer for the WST management acts as the first level of such avoidance. The pilot can change the WST slowly and precisely. A remained difference between WST and WSA is used for correcting the winding speed using circuits of an Engine Controller. This controller uses the WST value to provide instantaneous managing signals for power circuits, having feedback from them about the instantaneous phase state and power consumption of the engines. These values of the phase state and power consumption allow to deduce the WSA and EMR and apply an instantaneous management action to correct the WSA and maintain the EMR variations within moderate limits.

 

At the same time, the engine controller provides output of the WSA and EMR to indicators on the indicator panel of the cockpit. In particular, the EMR is represented as MR on the corresponding indicator, and the WSA has, in addition to its WSA indicator, the representation of the corresponding RPM value on another separate indicator.

 

The WST-trimmer can also be managed electromechanically using its servo. A low level of such management is provided by a pair of buttons on the control panel of the cockpit near this trimmer to incrementally increase or decrease the WST. Additionally, the central computer can provide a higher level of such management by having a more sophisticated treatment of the relationship between the WSA and EMR and more complex operations. For example, it can perform a command to stop the engines before locking the rotors. For such management the central computer uses the values of the WST, WSA and EMR provided by the engine controller. Additionally, the central computer can utilize the phase state, provided by the engine controller, for modeling the state of both rotors during flight.

 

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