Collapsible SMA Nose Cone for Air Vehicle Drag and Protection
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Solution Overview
Problem
Air vehicle seeker domes are vulnerable to damage during handling and aerodynamic drag during flight, and existing nose cone designs fail to provide adequate protection and drag reduction without increasing vehicle volume or requiring costly redesigns.
Innovation Solution
A collapsible nose cone made from shape memory alloy (SMA) that collapses for storage, deploys at launch to a memorized shape for protection and reduced drag, and is shed for terminal maneuvers, using temperature or strain-induced phase changes to achieve these transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blunt dome shape is used to protect the seeker, then protection is provided, but aerodynamic drag increases significantly at supersonic speeds
Solution Approach 1:
The nose cone is designed to change its shape dynamically based on flight conditions. During atmospheric flight, the nose cone maintains a blunt dome shape to protect the seeker. When the vehicle reaches supersonic speeds, the nose cone transitions to a more pointed shape to reduce aerodynamic drag. This dynamic shape transformation resolves the contradiction between protection and drag reduction.
Solution Approach 2:
The nose cone utilizes shape memory alloy materials that change their physical parameters (shape) in response to temperature changes. By controlling the phase transition of the SMA material, the nose cone can switch between a blunt protective shape and a pointed low-drag shape, allowing the vehicle to optimize both protection and aerodynamic performance at different flight stages.
2Object-generated harmful factors
If a fixed nose cone is used to reduce drag during flight, then aerodynamic performance improves, but the vehicle volume increases requiring redesign of launch tubes
Solution Approach 1:
The nose cone transitions from a fixed to a dynamic structure that can change volume and shape. During storage and launch, the nose cone is in a compact state that fits within existing launch tube constraints. During supersonic flight, it expands to a more pointed shape to reduce drag, thereby resolving the contradiction between drag reduction and volume constraints.
Solution Approach 2:
The nose cone utilizes shape memory alloy materials that change their physical parameters (shape and volume) in response to temperature changes. By controlling the phase transition of the SMA material, the nose cone can switch between a compact storage configuration and an expanded low-drag flight configuration, allowing the vehicle to optimize both drag reduction and volume constraints at different operational stages.
3Volume of moving object
If the nose cone is made collapsible to reduce volume, then storage space is reduced, but structural complexity increases
Solution Approach 1:
The nose cone utilizes shape memory alloy materials that automatically change their shape in response to temperature changes without requiring external actuators or complex control systems. The SMA material's inherent phase transition properties enable the nose cone to collapse for storage and expand for flight automatically, significantly reducing structural complexity while achieving volume reduction.
Solution Approach 2:
The nose cone is designed to be self-actuating through the use of shape memory alloy materials. The SMA material automatically transforms between collapsed and extended states based on temperature changes, eliminating the need for external motors, hydraulics, or control systems. This self-service capability achieves volume reduction while minimizing structural complexity.
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 SMA nose cone effectively protects the seeker dome and reduces aerodynamic drag during flight without increasing vehicle volume, allowing for retrofitting to existing air vehicles and integration into new designs without requiring changes to launch tubes or platforms, while enabling the seeker to image the scene during terminal maneuvers.
Implementation Method 1
The SMA is shape-set at elevated temperatures in its Austenite phase with a memorized shape... The temperature is reduced and the SMA collapsed to conform to the curvature of the sensor dome... the mechanism heats the SMA above the Austenite finish (Af) temperature to return the material to its memorized shape
Implementation Method 2
the SMA is stored below its Martensite finish (Mf) temperature in a temperature-induced Martensite phase... the SMA is stored above its Austenite finish temperature in which case collapsing the SMA places the material in a strain-induced Martensite phase
Implementation Method 3
collapsing the SMA places the material in a strain-induced Martensite phase... allowing the SMA to twist as it collapses reduces the strain
Data Source
AI summary
A nose cone formed from a shape memory alloy (SMA) having a recoverable strain of at least 2% collapses about the dome for storage, deploys at launch to protect the sensor dome and reduce drag during atmospheric flight and is shed to allow sensing for terminal maneuvers. The SMA is shape-set at elevated temperatures in its Austenite phase with a memorized shape having a radius of curvature greater than that of the sensor dome to reduce aerodynamic drag. The temperature is reduced and the SMA collapsed to conform to the curvature of the sensor dome within the recoverable strain for storage. A first mechanism is configured to return the collapsed SMA to its memorized shape at launch or prior to going supersonic. In one embodiment, the SMA is stored below its Martensite finish temperature in a temperature-induced Martensite phase in which case the mechanism heats the SMA above the Austenite finish temperature to return the material to its memorized shape. In another embodiment, the SMA is stored above its Austenite finish temperature in which case collapsing the SMA places the material in a strain-induced Martensite phase. The mechanism holds the collapsed SMA in place and the releases the stored energy allowing the SMA to return to the memorized shape.