Dual Mode Frangible Refueling Nozzle for Aircraft
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Solution Overview
Problem
Current in-flight refueling systems face challenges with the detachment of refueling probes from aircraft, particularly due to excessive forces such as bumps, stuck drogue release latches, improper drogue separation, and hose whip, which can lead to damage and Foreign Object Debris (FOD) risks.
Innovation Solution
A refueling probe assembly with a frangible tip and multiple break points, featuring a tethering member that remains intact at low tensile forces but ruptures at higher forces to control the detachment of the second tubular member from the first, preventing undesirable force transmission and ensuring safe separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the refueling probe uses a rigid connection between the first and second tubular members, then the structural strength is improved, but the risk of damage from excessive forces (bumps, hose whip, stuck latches) increases
Solution Approach 1:
The refueling probe is divided into multiple segments (first tubular member, second tubular member, nozzle) connected by frangible connections that can break at predetermined locations. This segmentation allows the probe to detach in a controlled manner when subjected to excessive forces, preventing damage to the aircraft while maintaining structural integrity during normal operation.
Solution Approach 2:
Frangible tips and controlled break points are pre-positioned at strategic locations along the refueling probe. These predetermined weak points act as sacrificial elements that will fail first under excessive force, cushioning the impact and preventing force transmission to critical components like the aircraft fuel system.
2Reliability
If the refueling probe uses a fixed connection that prevents detachment, then the reliability of fuel transfer is improved, but the ability to respond to abnormal conditions (excessive bump, stuck latch, hose whip) is reduced
Solution Approach 1:
The connection between tubular members transitions from a fixed rigid state during normal fuel transfer to a detachable state when abnormal forces are detected. The frangible connections remain intact during proper operation ensuring reliable fuel transfer, but can break at predetermined points when subjected to excessive forces or stuck latches, allowing the system to adapt to abnormal conditions.
Solution Approach 2:
The mechanical properties of the connection points are designed to change under different force conditions. During normal operation, the frangible connections maintain full strength for reliable fuel transfer. When force exceeds predetermined thresholds, the connections undergo controlled failure, changing the system state from connected to detached to prevent damage.
3Ease of operation
If the refueling probe allows easy detachment of the second tubular member, then the ease of operation is improved, but the risk of unintended separation under excessive forces increases
Solution Approach 1:
The frangible connections are pre-configured with predetermined break points that will fail at specific force thresholds. This preliminary preparation ensures that when excessive forces occur, the detachment happens at the correct location and time, rather than requiring manual intervention or risking uncontrolled separation.
Solution Approach 2:
The frangible connection acts as an intermediary element between the first and second tubular members. It provides a controlled interface that allows easy detachment when needed while preventing unintended separation through its predetermined failure characteristics. The intermediary absorbs the decision-making function of when and where detachment should occur.
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 effectively manages the detachment of the refueling probe, preventing damage to the aircraft and reducing FOD risks by allowing controlled separation under various operational conditions, ensuring safe and efficient refueling operations.
Implementation Method 1
The tethering member remains intact to connect the detached second tubular member to the first tubular member when a first tensile force is applied to the tethering member. The tethering member ruptures to disconnect the detached second tubular member from the first tubular member when a second tensile force greater than the first tensile force is applied to the tethering member.
Data Source
AI summary
An in-flight refueling probe includes a first tubular member secured to an aircraft and a second tubular member having a releasable connection with the first tubular member such that the second tubular member detaches from the first tubular member in response to a predetermined force applied to the connection. A nozzle secured to the second tubular member can be coupled to a receptacle of a fuel dispensing aircraft. A tethering member is connected to the first tubular member and one of the second tubular member and the nozzle. The tethering member remains intact to connect the detached second tubular member to the first tubular member when a first tensile force is applied to the tethering member. The tethering member ruptures to disconnect the detached second tubular member from the first tubular member when a second tensile force greater than the first tensile force is applied to the tethering member.