Deployable Fabric Fairing for Artillery Shell Drag Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Artillery shells experience increased drag due to airflow separation at the rear surface, limiting their range, and existing solutions like base-bleed techniques or inflatable tail sections have limitations in effectiveness and applicability.
Innovation Solution
A deployable fabric fairing driven by high-pressure gun gases is deployed after the shell clears the gun tube, using a piston and chamber system to reduce the area behind the shell, thereby reducing aerodynamic drag without the need for active propellants or inflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a rear surface that does not taper or tapers too quickly is used, then airflow separation is reduced, but the area behind the shell increases causing greater drag
Solution Approach 1:
The patent employs a dynamic fairing that transitions from a stowed configuration during launch to a deployed configuration during flight. This dynamic adjustment allows the shell to have a compact rear surface during firing (reducing launch tube pressure requirements) and an extended tapered fairing during flight (reducing base drag), thus resolving the contradiction between minimizing airflow separation and minimizing the area behind the shell.
Solution Approach 2:
The fairing is segmented into multiple panels that can independently deploy and form a tapered surface. This segmentation allows the fairing to be compact during launch and then expand into an aerodynamically optimized shape during flight, addressing both the airflow separation and drag area concerns.
2Productivity
If a deployable fairing is used to reduce drag, then range is extended, but device complexity increases
Solution Approach 1:
The patent uses pneumatic pressure from the propellant gases to automatically deploy the fairing. The high-pressure gases generated during firing naturally inflate the fairing without requiring separate actuators or complex mechanical deployment mechanisms, thus extending range while minimizing added complexity.
Solution Approach 2:
The fairing deployment system is self-actuating using the propellant gas pressure already present in the system. The fairing inflates automatically as the propellant burns and pressure builds, eliminating the need for external control systems or additional energy sources, thereby extending range without proportionally increasing complexity.
3Productivity
If base-bleed technique is used to reduce drag, then range increases, but propellant charge size must increase
Solution Approach 1:
The patent extracts the drag reduction function from the propellant charge itself by using the existing propellant gases to inflate the fairing. Instead of adding base-bleed propellant to the main charge, the system utilizes the propellant gases already present to serve a dual purpose: driving the shell and deploying the drag-reducing fairing, thus increasing range without increasing propellant quantity.
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 extends the range of artillery shells by minimizing drag forces through the deployment of a fabric fairing, which is locked in place after deployment, ensuring consistent drag reduction throughout the shell's trajectory.
Implementation Method 1
the pressure aft of the shell drops from the high pressure inside the tube to at or below the atmospheric pressure outside the tube. The high-pressure gun gasses stored in the chamber produce a pressure that acts on the top surface of the piston to drive the piston aft against the much lower atmospheric pressure behind the shell
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A employable fairing is driven off of high-pressure gun gases to reduce aerodynamic drag and extend the range of the artillery shell. An artillery shell is provided with a fabric fairing and a piston attached thereto in a rear section of the shell in a stowed state and a chamber. During launch high-pressure gun gasses are captured and stored in the chamber. Once the shell clears the end of the artillery tube, the pressure aft of the shell drops from the high pressure inside the tube to atmospheric pressure outside the tube. The high pressure gun gasses stored in the chamber act over the top surface of the piston to drive the piston aft against the much lower pressure behind the projectile to deploy the fabric fairing attached thereto to reduce the base area of the projectile creating or extending the boat-tail of the shell, hence reduce aerodynamic drag. The aft driven piston engages a locking mechanism that locks the piston in a deployed position.