Rear-mounted Jet Engine Vertical Maintenance Access
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Solution Overview
Problem
Aircraft configurations with odd numbers of turbojet engines face challenges in aerodynamic integration, maintenance accessibility, and noise reduction, particularly when engines are mounted at the rear, leading to inefficiencies and increased maintenance complexities.
Innovation Solution
The proposed solution involves mounting turbojet engines at the rear of the aircraft using conventional nacelles attached to a horizontal or vertical aerodynamic surface, allowing for easy installation and removal, improved aerodynamic integration, and enhanced acoustic masking to reduce noise radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If jet engines are mounted at the rear of the fuselage, then aerodynamic integration is improved, but maintenance accessibility deteriorates
Solution Approach 1:
The patent positions jet engines at the rear of the aircraft but elevates them vertically above the fuselage axis, utilizing the vertical dimension to resolve the contradiction. This spatial reconfiguration allows engines to benefit from improved aerodynamic integration at the rear while maintaining accessibility through vertical movement during maintenance operations.
Solution Approach 2:
The patent introduces a vertical movement mechanism as an intermediary means to facilitate maintenance operations. This mechanism allows maintenance personnel to access engines positioned at the rear by enabling vertical movement, thus mediating between the conflicting requirements of rear mounting for aerodynamic benefits and accessibility for maintenance.
2Strength
If jet engines are placed close to the fuselage, then structural integration is improved, but aerodynamic efficiency deteriorates
Solution Approach 1:
The patent resolves this contradiction by utilizing the vertical dimension. Engines are positioned at the rear but elevated above the fuselage axis, allowing close structural integration while maintaining sufficient distance from the fuselage surface to preserve aerodynamic efficiency and reduce flow distortion.
3Ease of operation
If conventional nacelles are used for rear engine mounting, then ease of installation is improved, but aerodynamic integration deteriorates
Solution Approach 1:
The patent applies universality by adapting conventional nacelle designs for rear engine mounting. The nacelles are designed to be multi-functional, capable of accommodating engines in rear positions while maintaining compatibility with standard installation procedures, thus bridging the gap between ease of installation and aerodynamic integration.
Solution Approach 2:
By positioning engines vertically above the fuselage axis rather than directly on the fuselage surface, the patent enables the use of conventional nacelles for rear mounting. This vertical arrangement allows standard nacelle designs to be adapted while achieving improved aerodynamic integration through better airflow characteristics.
4Object-affected harmful factors
If noise reduction measures are implemented, then acoustic pollution is reduced, but jet engine efficiency deteriorates
Solution Approach 1:
The patent addresses noise reduction by utilizing the vertical dimension to position engines above the fuselage axis. This configuration creates acoustic masking effects where the fuselage and tail structures partially shield the engines from ground-level noise propagation, reducing acoustic pollution without requiring modifications that would compromise engine efficiency.
Data Source
AI summary
When an aircraft is propelled by at least one jet engine fixed in a rear part of the aircraft, at least one substantially horizontal rear aerodynamic surface, the rear horizontal surface, is arranged at the rear of the aircraft and at least one jet engine is fixed under the rear horizontal surface by an attachment mast fixed by its upper part to the rear horizontal surface and maintains, by its lower part, the jet engine. The rear horizontal surface is also the horizontal tail unit of the aircraft or a horizontal surface maintained above the fuselage. The rear surfaces and the fuselage are arranged such that the engines are installed and removed using a vertical movement of the engines, which are advantageously one, two or three in number, in the rear zone of the aircraft.