Internal Sensor Mach Number Measurement for Munitions
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Solution Overview
Problem
Existing systems for measuring Mach number and dynamic pressure in munitions rely on external sensors that can be inconvenient, prone to clogging, and provide unreliable results, especially in dynamic flight conditions, leading to suboptimal autopilot performance.
Innovation Solution
Implementing a system with internal sensors, including an accelerometer and pressure sensor, to calculate Mach number and dynamic pressure from axial acceleration and static pressure measurements, eliminating the need for external sensors and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors (pitot tubes) are used to measure dynamic pressure, then measurement capability is provided, but the sensors become clogged with debris and produce unreliable results
Solution Approach 1:
The patent extracts the measurement function from external sensors and relocates it to internal sensors within the munition body. The dynamic pressure measurement is performed by internal pressure sensors that detect pressure changes within the sealed or partially sealed sensor housing, eliminating the need for external pitot tubes that are susceptible to clogging and damage.
Solution Approach 2:
The patent introduces an intermediary sensor housing structure that mediates between the external environment and the measurement function. The housing with its specific geometry and opening configurations acts as an intermediary that converts external dynamic pressure conditions into measurable internal pressure changes, while protecting the sensor from direct exposure to debris and harsh conditions.
2Measurement precision
If external sensors are mounted on the munition surface, then dynamic pressure can be measured, but the sensors can be damaged during transport or launch under high G environment
Solution Approach 1:
The patent embeds the pressure sensor within the munition body structure, creating a nested configuration where the sensor is protected by the surrounding housing and structural elements. This nesting provides mechanical protection during launch and transport while maintaining the sensor's ability to measure dynamic pressure through the housing structure.
Solution Approach 2:
The sensor housing is designed with beforehand cushioning features including shock-absorbing materials, compliant mounting structures, and protective geometries that cushion the sensor against high G forces and mechanical impacts during launch and transport, preventing damage before it occurs.
3Measurement precision
If pitot tubes are used for measurement, then dynamic pressure can be detected, but adjacent rockets can clog the pitot tube with exhaust fumes
Solution Approach 1:
The patent removes the measurement function from external pitot tubes that are vulnerable to exhaust fume contamination. Instead, internal pressure sensors within the munition body detect dynamic pressure through pressure changes in the housing structure, completely eliminating the problem of exhaust fumes clogging the sensor opening.
Solution Approach 2:
The housing structure serves as an intermediary that transmits dynamic pressure information to the internal sensor while blocking the direct path of exhaust fumes from adjacent rockets. The housing geometry and sealing mechanisms create a protective barrier that prevents contamination while maintaining pressure transmission.
4Extent of automation
If preprogrammed gain scheduling is used, then autopilot control can be implemented, but the system cannot adapt to differing flight paths and conditions
Solution Approach 1:
The patent implements feedback by using real-time dynamic pressure measurements from internal sensors to continuously update and adjust autopilot gain parameters. This closed-loop feedback system allows the autopilot to adapt to actual flight conditions and deviating trajectories, replacing rigid preprogrammed schedules with dynamic, condition-based control adjustments.
Solution Approach 2:
The patent transitions from static preprogrammed gain schedules to dynamic gain adjustment based on real-time measurements. The autopilot control parameters are made dynamic, continuously adapting to changing flight conditions, Mach numbers, and dynamic pressure values as measured by the internal sensors throughout the munition's flight trajectory.
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
Enables real-time measurement of dynamic pressure and Mach number, enhancing autopilot performance by providing adaptive control and maintaining sensor integrity across various flight conditions.
Implementation Method 1
An internal accelerometer is located within the system body
Implementation Method 2
An internal pressure sensor is located in the system body, wherein the internal pressure sensor is not hermetically sealed within the system body and capable of measuring the static pressure of the ambient atmosphere
Data Source
AI summary
A system for calculating airspeed and dynamic pressure comprises a system body, an internal accelerometer, located within the system body, an internal pressure sensor, located in the system body, the internal pressure sensor being not hermetically sealed within the system body and capable of measuring the static pressure of the ambient atmosphere, and a processor in reception of the internal accelerometer, and the internal pressure sensor, capable of calculating Mach number via an axial acceleration, and capable of calculating a dynamic pressure and a true airspeed via the Mach number.