Retractable Aircraft Undercarriage Reducing Drag and Fuel Consumption
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Solution Overview
Problem
Conventional tubular undercarriages for rotary wing aircraft, such as helicopters, suffer from aerodynamic inefficiencies, increased fuel consumption, and unfavorable aesthetics, while also being heavy and prone to resonance issues during landing, which can damage the aircraft.
Innovation Solution
A retractable undercarriage system with threaded rod and motor-driven pivot arms and skids made of lightweight materials, such as aluminum or composite materials, that can absorb landing impacts and rotor-induced motion without increasing weight, featuring a resilient sleeve for damping and electrical or hydraulic control for improved aerodynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid tubular undercarriage structure is used, then the undercarriage can withstand high stress and absorb landing energy, but it harms aerodynamics and increases fuel consumption
Solution Approach 1:
The undercarriage transitions from a static rigid structure to a dynamic retractable system. The longitudinal portions can move between extended and retracted positions based on flight conditions, allowing the structure to adapt its configuration to minimize aerodynamic drag during cruise while maintaining structural integrity during landing.
Solution Approach 2:
The undercarriage is divided into separate retractable longitudinal portions that can independently move. Each portion can be retracted into the aircraft body or extended outward, allowing selective configuration based on operational needs to balance aerodynamic efficiency and landing capability.
2Loss of energy
If a retractable undercarriage is implemented, then aerodynamics improve and fuel consumption decreases, but the device complexity increases
Solution Approach 1:
The undercarriage system incorporates self-supporting motors that can operate autonomously to move the longitudinal portions between positions. The threaded rods with motor-driven screws provide self-contained actuation mechanisms that reduce the need for external control systems and simplify the overall actuation architecture.
Solution Approach 2:
Traditional mechanical linkages and hydraulic/pneumatic actuation systems are replaced with electric motors directly integrated into the threaded rod mechanisms. This substitution simplifies the control system, reduces leakage issues, and allows for more precise control of the retractable portions.
3Strength
If metal or composite tubular structures are used, then the undercarriage can absorb landing impacts, but it presents resonance risks and has unfavorable appearance
Solution Approach 1:
The physical parameters of the undercarriage structure are modified by making the longitudinal portions retractable rather than fixed. This changes the structural configuration parameter, allowing the system to avoid resonance by retracting the tubular portions during cruise flight when aerodynamic resonance could occur, while extending them only when needed for landing impact absorption.
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
The solution enhances aerodynamics, reduces fuel consumption, maintains mechanical integrity, and simplifies maintenance while avoiding weight increase, offering a cost-effective and efficient undercarriage system.
Implementation Method 1
the drive means comprise a respective threaded rod having one end that is free and having its other end that is designed to be hinged to a stationary support, said threaded rod passing through one end, referred to as the inside end of the corresponding pivot arm
Implementation Method 2
each pivot arm includes a pivot inserted in a resilient sleeve for damping the motion transmitted to said undercarriage, as a function of frequencies of the rotor system
Data Source
AI summary
An undercarriage for a rotary wing aircraft, includes a tubular structure (7) with skids, the tubular structure (7) being designed to be mounted under or in a bottom portion (4) of the aircraft, the undercarriage being characterized in that the tubular structure (7) includes left and right longitudinal portions that are retractable, each of which portions is suitable for moving between a retracted position in a cruising flight configuration and a deployed configuration in a landing configuration.