Rotatable Fastener for Aircraft Store Drag Reduction
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Solution Overview
Problem
Existing retractable hooks for securing missiles to aircraft are bulky and heavy due to the need to withstand high stresses during flight, take-off, and landing, leading to increased drag and reduced fuel efficiency.
Innovation Solution
A rotatable fastening system with L-shaped legs and double actuators that securely attach to the aircraft, allowing for efficient stress distribution and reduced size and weight, while rotating to minimize drag during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If linearly retractable hooks are used to withstand large stresses during aircraft operation, then the hooks can maintain structural integrity, but the space and weight within the missile increase significantly
Solution Approach 1:
The patent applies a rotatable fastener that can dynamically change its orientation between an extended position during launch (to withstand stress) and a retracted position during flight (to reduce drag). This dynamic reconfiguration allows the system to optimize its structural properties based on operational phase, eliminating the need for oversized permanent stress-resistance structures
Solution Approach 2:
The invention introduces rotational movement as an additional degree of freedom, allowing the fastener to transition between dimensional states. By rotating the fastener body, the engagement surfaces can be positioned optimally for stress distribution during launch, then repositioned to minimize aerodynamic drag during flight, effectively using spatial reconfiguration to resolve the contradiction
2Strength
If linearly retractable hooks are used to withstand large stresses during aircraft operation, then the hooks can maintain structural integrity, but the space required within the missile increases
Solution Approach 1:
The rotatable fastener dynamically adjusts its configuration based on operational requirements. During launch, the fastener extends to provide maximum stress resistance. During flight, it rotates to a compact position that minimizes the volume it occupies within the missile, thereby reducing the overall space requirement without compromising strength when needed
3Strength
If fixed hooks are used on the missile, then the hooks can withstand large stresses during aircraft operation, but the drag coefficient of the aircraft store increases
Solution Approach 1:
The fastener system transitions from a static fixed-hook design to a dynamic rotatable design. During the launch phase, the fastener extends to engage with the aircraft pylon for maximum stress resistance. Once launched, the fastener rotates to retract behind the missile body, eliminating the protruding geometry that causes high drag, thus dynamically optimizing both strength and aerodynamic performance
Solution Approach 2:
The rotatable fastener is pre-configured to automatically assume the optimal position for each operational phase. The rotation mechanism is designed so that the fastener naturally transitions to the retracted position after launch, preliminarily preparing the aerodynamic profile for efficient flight before drag becomes a significant factor
Data Source
AI summary
A fastening system with a rotatable fastener that may secure an aircraft store to an aircraft and may rotate to reduce a drag coefficient of the aircraft store. Reducing the drag coefficient of the aircraft store may increase fuel efficiency of the aircraft store by requiring less energy to propel the aircraft store at a given speed or acceleration.The rotatable fastener allows the aircraft store to attach to the aircraft and to possess a low drag coefficient once the aircraft store is deployed. The rotatable fastener member may be configured to conform to attachment interface standards, such as Standardization Agreement (“STANAG”) 3842 or any other suitable aircraft store attachment interface standard.