Fixed Outboard Engine Tiltrotor with Angled Rotation Spindle
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Solution Overview
Problem
Existing rotorcraft drive systems face challenges in efficiently transitioning between hover and forward flight modes while maintaining power transmission and structural integrity, particularly with fixed outboard engines and spindle configurations that compromise aerodynamics and structural support.
Innovation Solution
A rotorcraft drive system featuring a fixed outboard engine positioned between mid-wing and aft-wing spars, with an angled rotation spindle supported by multiple bearings and a tilt axis driveshaft connected via bevel gears, allowing seamless power transmission to the proprotor gearbox during transitions between hover and forward flight positions without loss of power, and providing structural continuity for rotor loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the engine is positioned forward of the spar to improve hover performance and reduce structural weight, then the main rotor cannot be directly coupled to the engine, requiring complex drive paths with multiple shafts and gears that increase device complexity and potential power loss
Solution Approach 1:
The drive system is segmented into distinct functional components: the engine remains fixed forward of the spar for optimal hover performance, while the proprotor pylon with its own gearbox is positioned at the wing tip. The drive path is divided into manageable segments (interconnect drive shaft, tilt axis driveshaft, gears) that can be independently optimized and maintained, reducing overall system complexity despite the extended drive path.
Solution Approach 2:
An interconnect drive shaft acts as an intermediary component, mechanically coupling the engine (fixed forward of spar) to the proprotor pylon (at wing tip). This intermediary shaft allows power transmission across the structural boundary (through the spar) without requiring the engine to be repositioned or the pylon to be directly coupled to the engine, thus maintaining both hover performance and structural integrity.
2Adaptability or versatility
If the spindle is allowed to rotate between hover and forward flight positions, then the proprotor can transition between vertical and horizontal orientations, but maintaining power transmission throughout the transition requires a complex system of gears and shafts that may cause power loss
Solution Approach 1:
The tilt axis driveshaft is designed to dynamically adjust its orientation as the proprotor pylon transitions between hover and forward flight positions. The driveshaft rotates with the pylon, maintaining continuous mechanical coupling between the engine and proprotor gearbox throughout the transition. This dynamic adaptation ensures uninterrupted power transmission while accommodating the full range of motion required for flight mode changes.
Solution Approach 2:
The drive system maintains continuous power transmission during the entire transition process. The interconnect drive shaft and tilt axis driveshaft are designed to remain engaged throughout the rotation, ensuring that the useful action of power transmission never中断. This continuity eliminates power loss that would occur if the drive path were disengaged or reconfigured during transition.
3Device complexity
If the engine is fixed in position to simplify the drive system, then the drive path becomes longer requiring more shafts and gears, but this fixes the engine at a suboptimal location for both hover and forward flight performance
Solution Approach 1:
The system employs asymmetric positioning: the engine is fixed forward of the spar (asymmetric location) to optimize hover performance, while the proprotor pylon is positioned at the wing tip (asymmetric location). This asymmetric configuration accepts a longer drive path but gains superior performance in both hover and forward flight modes, as the engine location is optimized for the more demanding hover condition.
4Shape
If the spindle gearbox is positioned at the wing tip to improve aerodynamics, then the drive path must pass through the wing structure requiring shafts to pass through spars that compromise structural integrity
Solution Approach 1:
The proprotor pylon with its gearbox is extracted and positioned at the wing tip, separate from the engine location. This allows the aerodynamic shape of the wing to be maintained without the engine or drive system components interfering with the airflow. The drive path is routed through the wing structure in a way that minimizes structural compromise, with shafts passing through designated openings in the spars.
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 structural weight reduction, improves hover and cruise performance, and accommodates various wing sweep angles, ensuring efficient power transmission and structural integrity across different flight modes.
Implementation Method 1
a tilt axis driveshaft connected to the engine by a bevel gear, and connected to a plurality of gears and shafts that transmit power from the engine to a proprotor gear box
Implementation Method 2
an angled rotation spindle supported by multiple bearings
Data Source
AI summary
The present invention includes a rotorcraft drive system comprising: an engine positioned at an end of a wing between a mid-wing spar and an aft-wing spar; a spindle positioned forward from the engine, the spindle capable of rotation between a hover and forward flight position, wherein the spindle rotates about a rotation bearing on an inboard split rib and an outboard tip rib or in a cantilevered spindle configuration supported by the inboard tip rib; and a tilt axis driveshaft connected to the engine, wherein the tilt axis drive shaft connects to a plurality of gears and shafts that transmit power from the engine to a proprotor gear box when the spindle is in: a forward position, a hover position, and during a transition between the forward position and the hover position without loss of power to the proprotor gear box.