Propellant Crater Design for Controlled Gas Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing propellants in gun cartridges generate gas pressure rapidly at the start, leading to high initial pressure followed by a decrease as the surface area burns down, resulting in inefficient projectile acceleration and increased maximum pressure tolerance requirements for gun barrels, making them heavy and costly.
Innovation Solution
A propellant surface is coated with a deterrent to create spaced areas that, when ignited, generate craters exposing increasing surface areas, controlling the rate of gas pressure increase by progressively increasing the burning surface area, allowing for a more gradual and efficient pressure build-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the outer surface of propellant grains is used for burning, then the propellant ignites quickly and generates gas pressure, but the surface area rapidly decreases leading to extremely high initial pressure followed by progressively lesser pressure
Solution Approach 1:
The propellant grain is segmented into multiple burning surfaces by creating hollow internal cavities. This segmentation allows the burning process to occur simultaneously on multiple surfaces (outer surface and internal cavity surfaces), preventing rapid surface area depletion and controlling pressure generation rates.
Solution Approach 2:
Hollow internal cavities are nested within the propellant grain structure. These internal cavities provide additional burning surfaces that are consumed progressively, extending the burning duration and controlling the pressure profile without requiring external surface area reduction.
2Stress or pressure
If deterrent material is applied to propellant surfaces to slow down initial gas evolution, then the initial pressure spike is reduced, but the overall gas generation rate decreases
Solution Approach 1:
The burning surface is extended from a two-dimensional outer surface to include three-dimensional internal cavity surfaces. This dimensional transition provides additional burning area that compensates for the deterrent coating's retarding effect, maintaining overall gas generation productivity while controlling initial pressure spikes.
Solution Approach 2:
Hollow internal cavities are pre-formed within the propellant grain before ignition. These pre-existing structures provide immediate additional burning surfaces upon ignition, ensuring controlled pressure generation from the start without requiring deterrent materials that would reduce overall productivity.
3Volume of stationary object
If the volume occupied by gas increases as the projectile moves downstream, then the gas pressure decreases, but this reduces the accelerating force on the projectile
Solution Approach 1:
The propellant burning process is designed to continue producing gas pressure throughout the entire projectile travel distance. By providing extensive internal cavity burning surfaces, the propellant maintains effective pressure generation even as gas volume increases, ensuring continuous accelerating force from upstream to downstream end of the barrel.
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
This solution enables a controlled and sustained increase in gas pressure, reducing the maximum pressure tolerance requirement, allowing for lighter and less expensive gun barrel materials and improving projectile acceleration.
Implementation Method 1
a deterrent applied to a second surface area defined by the first surface area
Implementation Method 2
when the primer is activated, the third surface area of the propellant is ignited
Implementation Method 3
the third surface area of the propellant while burning exposes a progressively increasing surface area of the propellant for burning together with an associated increased generation of gas
Data Source
AI summary
A device is disclosed for controlling a rate of gas pressure increase generated by a propellant for propelling a projectile from an upstream towards a downstream end of a gun barrel. The device includes a first surface area defined by the propellant and a deterrent applied to a second surface area defined by the first surface area, the second surface area being less than the first surface area. The arrangement is such that the second surface area defines a deterrent free third surface area of the propellant. A primer is operatively disposed relative to the third surface area such that when the primer is activated, the third surface area of the propellant is ignited. The arrangement is such that firstly, while the third surface area is burning and generating gas between the upstream end of the gun barrel and the projectile, the rate of gas pressure increase begins to propel the projectile towards the downstream end of the gun barrel. Secondly, the third surface area of the propellant while burning exposes a progressively increasing surface area of the propellant for burning together with an associated increased generation of gas, the increasing surface area of the propellant defining a concave crater, the crater having a wall which progressively increases in surface area during the burning such that the rate of increase in gas pressure continues to increase for accelerating the projectile towards the downstream end of the gun barrel.