Rotor-to-Wing Conversion for Tail Sitter Aircraft
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Solution Overview
Problem
Tail sitter aircraft face inefficiencies in propulsion during forward flight, limiting their endurance due to propulsion system inefficiencies and difficulties in control during hover and vertical takeoff/landing transitions.
Innovation Solution
The design incorporates a dual rotor configuration for vertical takeoff and landing, with one rotor assembly providing forward thrust and the other forming wings for lift during forward flight, featuring torque matching, cyclic, and collective control mechanisms to optimize thrust and lift generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rotary propulsion system is used for vertical takeoff and landing, then vertical thrust is generated, but propulsion efficiency during forward flight deteriorates
Solution Approach 1:
The rotor assembly is made dynamically reconfigurable, allowing it to transition between rotational modes. During vertical takeoff and landing, the rotor rotates about the longitudinal axis to generate vertical thrust. During forward flight, the rotor transitions to rotating about the vertical axis, converting from a helicopter-like propulsion system to a propeller-like configuration that generates horizontal thrust while the wing generates lift, thereby improving propulsion efficiency during forward flight
Solution Approach 2:
The invention changes the operational parameters of the rotor assembly by altering its axis of rotation. The rotor can change its rotational axis from longitudinal (for vertical thrust) to vertical (for forward thrust), effectively changing the direction and type of thrust generated. This parameter change allows the same component to optimize performance for different flight phases
2Adaptability or versatility
If a tail sitter configuration is used for vertical takeoff and landing, then runway requirement is eliminated, but control capability during hover deteriorates
Solution Approach 1:
The control system is made dynamic and adaptive based on flight phase. During hover and vertical operations, the rotor rotates about the longitudinal axis providing full rotational control for hover management. During forward flight, the system transitions to propeller mode with the rotor rotating about the vertical axis. The flight control system dynamically adjusts control inputs and rotor behavior based on the current flight phase, maintaining ease of operation across all modes
Solution Approach 2:
The rotor assembly serves multiple functions depending on its operational mode. It can generate vertical thrust during takeoff and landing, provide hover control, and generate forward thrust during cruise. The same physical component adapts its function based on the flight phase, reducing the need for separate specialized systems while maintaining control capability
3Power
If dual rotor assemblies are used for vertical thrust, then vertical takeoff and landing is enabled, but device complexity increases
Solution Approach 1:
The invention merges the functions of multiple rotor systems into a single reconfigurable rotor assembly. Instead of having separate rotors for vertical thrust and forward flight, one rotor assembly performs both functions by changing its axis of rotation. This combining of functions reduces mechanical complexity, eliminates the need for multiple independent rotor systems, and simplifies the overall aircraft architecture while maintaining vertical thrust capability
Solution Approach 2:
The single rotor assembly is designed to be universal, performing multiple functions across different flight phases. It generates vertical thrust during takeoff and landing, provides hover control, and generates forward thrust during cruise flight. This multi-functionality eliminates the need for separate specialized rotor systems, thereby reducing device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the aircraft's endurance and control capabilities by improving propulsion efficiency during forward flight and stabilizing vertical takeoff and landing operations, while reducing aircraft geometry for storage and increasing versatility.
Implementation Method 1
A first rotor assembly positioned proximate the first rotor station and a second rotor assembly positioned proximate the second rotor station rotate about the fuselage to provide vertical thrust
Implementation Method 2
The first rotor assembly rotates about the fuselage to provide forward thrust
Implementation Method 3
the second rotor assembly is non-rotatable about the fuselage forming wings to provide lift
Data Source
AI summary
A tail sitter aircraft includes a fuselage having a forward portion and an aft portion. The forward portion of the fuselage includes first and second rotor stations. A first rotor assembly is positioned proximate the first rotor station. A second rotor assembly is positioned proximate the second rotor station. A tailboom assembly extends from the aft portion of the fuselage. The tailboom assembly includes a plurality of landing members. In a vertical takeoff and landing mode of the aircraft, the first and second rotor assemblies rotate about the fuselage to provide vertical thrust. In a forward flight mode of the aircraft, the first rotor assembly rotates about the fuselage to provide forward thrust and the second rotor assembly is non-rotatable about the fuselage forming wings to provide lift.