Hinged Cradle for Aircraft Fan Cowls Reducing Hyperstaticity
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Solution Overview
Problem
The existing engine mounting structures for aircraft experience significant deformation and misalignment of fan cowls during stress conditions like take-off and turbulence, leading to degraded aerodynamic performance due to high hyperstaticity and direct mechanical links that constrain the cradle's movement.
Innovation Solution
The engine assembly features a fore aerodynamic structure with a cradle that is hinge-mounted to the fan housing and air intake, allowing the fan cowls to move between open and closed positions, decoupling from the engine mounting structure in closed position to reduce hyperstaticity and accommodate deformations, and supported by the thrust reverser system, maintaining the nominal geometry of the nacelle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cradle is directly mechanically linked to the engine mounting structure, then the structural strength and stress transmission are improved, but the deformation and misalignment of fan cowls increase under stress conditions
Solution Approach 1:
The cradle is made movable relative to the engine mounting structure through a hinge connection at the fore end, allowing it to dynamically adjust its position and orientation in response to stress conditions, thereby maintaining fan cowl geometry while still providing structural support
2Reliability
If the fan cowls are locked to each other in closed position, then the aerodynamic sealing is improved, but the hyperstaticity and constraint on cradle movement increase
Solution Approach 1:
The fan cowls are designed to be hinged rather than rigidly locked, allowing them to maintain a closed sealing position during normal operation while permitting controlled movement of the cradle under stress conditions, thus reducing hyperstaticity while maintaining aerodynamic reliability
3Manufacturing precision
If the cradle is fixed to the engine mounting structure, then the manufacturing precision and assembly alignment are improved, but the adaptability to stress-induced deformations decreases
Solution Approach 1:
The hinge connection at the fore end of the cradle allows for controlled movement and adaptation to stress-induced deformations while maintaining proper alignment through the hinge's rotational degrees of freedom, combining adaptability with functional alignment
Data Source
AI summary
The invention relates to an engine assembly for aircraft in which the coupling device comprises a fore aerodynamic structure having a cradle equipped with an aerodynamic cowling, the cradle being hinge mounted on the air intake of the engine, and the fan cowls being mounted to move on the cradle so as to be able to occupy an open position as well as a closed position in which they are supported by the air intake and by a thrust reverser. According to the invention, when the cowls are in open position, the cradle adopts a first configuration in which its aft end rests on a span of the engine mounting structure, and when the cowls are in closed position, the cradle, borne by said cowls, adopts a second configuration in which it is lacking any direct mechanical link with the other elements of the engine mounting structure.