Coaxial Rotor and Propeller Control for Level High-Speed Flight
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Solution Overview
Problem
Rotary wing aircraft lack sufficient maneuverability beyond vertical take-off and land capabilities, and existing control systems are inefficient in transitioning between hover and forward flight, limiting their operational range and agility.
Innovation Solution
A dual rotor, counter-rotating coaxial helicopter design with a propeller for translational thrust, coupled with a fly-by-wire flight control system that allows independent control of rotor pitch and propeller thrust, enabling stable flight at various airspeeds and attitudes without the need for tilting the airframe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional helicopter design with main rotor for lift and tail rotor for anti-torque is used, then vertical take-off and landing capability is achieved, but maneuverability beyond basic hover and forward flight is limited
Solution Approach 1:
The aircraft separates the functions of lift generation and translational thrust into distinct systems: the main rotor assembly provides lift while the propeller provides forward thrust. This functional segmentation allows independent control of vertical and horizontal motion, dramatically increasing maneuverability without requiring complex coupling between control systems.
Solution Approach 2:
The flight control system dynamically adjusts rotor pitch and propeller thrust independently based on desired flight attitude and speed. The system can maintain stable flight at various airspeeds from 0 to 240 knots while maintaining constant altitude, with the ability to hover with nose pitched up or down, demonstrating dynamic adaptability across multiple flight regimes.
2Productivity
If a flight control system with lift control algorithm is used to coordinate transition between hover and forward flight, then transition efficiency is improved, but the system complexity and noise increase
Solution Approach 1:
The control system is segmented into independent algorithms: a lift control algorithm that manages rotor pitch for vertical motion and a separate translational control algorithm that manages propeller thrust for horizontal motion. This segmentation allows optimized control for each function, improving transition efficiency while reducing the noise associated with complex integrated control systems.
3Speed
If the aircraft tilts the airframe to achieve forward flight, then translational movement is enabled, but drag increases and stability is reduced
Solution Approach 1:
The aircraft maintains a level airframe attitude during forward flight by separating the thrust generation function (propeller) from the lift generation function (main rotor). The propeller provides translational thrust while the rotor maintains vertical lift, allowing the airframe to remain stable and level across the full airspeed range from hover to 240 knots, significantly reducing drag compared to tilted airframe configurations.
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
Enables the aircraft to maintain stable pitch attitudes at various airspeeds from 0 to 240 knots while maintaining constant altitude, increasing maneuverability and reducing noise through independent control of rotor and propeller systems, and reduces drag with a sealed rotor hub fairing.
Implementation Method 1
Aircraft and Method of Orienting an Airframe of an Aircraft... dual, counter rotating, coaxial main rotor assembly... capable of vertically taking off and landing
Implementation Method 2
translational thrust system... propeller... capable of flying at airspeed of about 0 knots to 240 knots
Implementation Method 3
reduces drag with a sealed rotor hub fairing
Data Source
Figure 1
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AI summary
An aircraft includes an airframe, an extending tail, a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly, a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; and a horizontal stabilizer positioned at the extending tail, the horizontal stabilizer having one or more elevators; wherein the aircraft is configured to mix at least two of the main rotor assembly collective pitch, the main rotor assembly cyclic pitch, the elevator deflection, and the translational thrust system thrust to trim the aircraft attitude.