In-flight Refueling Probe Frangible Fastener Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing in-flight refueling systems lack an effective mechanism for automatic separation of the nozzle from the refueling probe assembly when stuck, potentially causing damage to both aircraft and requiring non-reusable components or generating debris upon separation.
Innovation Solution
A refueling probe design featuring a tubular member with a convex end and a cylindrical member connected by strength-limited fasteners, such as rivets, that break under a specific load to separate the nozzle from the receptacle without causing damage, allowing for reusability and minimal debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fuse-based separation system is used to prevent damage when the nozzle becomes stuck, then damage to aircraft is prevented, but the system requires complex automatic actuation mechanisms and may leave debris upon separation
Solution Approach 1:
The patent employs disposable fasteners (such as breakaway bolts or frangible connectors) that are designed to fail at a predetermined load. These fasteners are replaced after each use, eliminating the need for complex automatic separation systems while ensuring clean separation without debris. The fastener itself becomes the sacrificial element that protects the aircraft.
2Extent of automation
If a bolted flange designed to break under overload is used, then automatic separation is achieved, but a portion of the refueling line remains attached to the aircraft being refueled
Solution Approach 1:
The refueling probe assembly is segmented into distinct components connected by frangible fasteners. The fastener is positioned such that when it fails, both the nozzle and the refueling line separate completely from the aircraft being refueled. This segmentation ensures that no portion of the refueling system remains attached after separation.
3Stability of the object's composition
If a tubular retainer held together by a cup-shaped clamp is used, then the probe structure is maintained, but the retainer can hit the aircraft being refueled upon breaking
Solution Approach 1:
The potential harmful element (the retainer or clamp) is extracted or isolated from the separation path. The frangible fastener is designed to fail in a controlled manner that directs debris away from the aircraft, or the retainer is positioned such that it cannot contact the aircraft upon separation. This removes the harmful impact effect while maintaining structural integrity during normal operation.
4Ease of operation
If a hydraulically actuated moveable sleeve with ball detents is used for emergency disconnect, then separation can be achieved, but the system does not automatically operate upon overload and requires complex actuation mechanisms
Solution Approach 1:
The fastener system is designed to automatically detect and respond to overload conditions without requiring external actuation. The frangible fastener inherently senses the excessive load through stress concentration and fails automatically when the predetermined load is exceeded, providing self-service separation functionality.
Data Source
AI summary
An in flight refueling probe for an aircraft includes a circular shaped hollow tubular member having a first end attached to the aircraft and a second end extending from the aircraft terminating in an external convex shape with a plurality of first holes equally spaced thereabout. A cylindrical member having a first end with an internal curved surface convex shaped end of the tubular member with a plurality of second holes there through in alignment with the plurality of first holes in the second end of the tubular member with fasteners installed in the holes joining the cylindrical member to the tubular member. The fasteners have a strength limited to a value that will break under a specific load on the probe. A nozzle assembly is mounted to the second end of the cylindrical member for coupling to the receptacle on a fuel dispensing aircraft.