Variable Thrust Rocket Motor for Non-Lethal Projectile Kinetic Energy Control
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Solution Overview
Problem
Existing gun-launched non-lethal anti-personnel projectiles face limitations in maintaining effective impact momentum at both close and long ranges, as limiting launch velocity or mass affects their performance, leading to suboptimal performance beyond 400 meters.
Innovation Solution
A gun-launched non-lethal anti-personnel cartridge with a variable thrust, solid propellant rocket motor that maintains constant kinetic energy by varying the burn rate and thrust profile, using multiple propellant segments with different burn rates and cross-sectional areas to ensure effective performance from 5 meters to 400 meters without exceeding lethal thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the launch velocity of the projectile is limited to maintain non-lethal impact momentum at close range, then the projectile can safely impact at close range, but the projectile achieves lower downrange velocities and experiences longer flight times resulting in greater gravity drop, reducing performance at longer ranges
Solution Approach 1:
The rocket motor provides continuous variable thrust during flight to dynamically adjust the projectile's velocity profile. The thrust magnitude varies with time and altitude to compensate for gravity and drag, maintaining optimal downrange velocity without exceeding close-range lethal thresholds. This dynamic propulsion allows the projectile to achieve both safe close-range impact and effective long-range performance.
Solution Approach 2:
The system changes the propulsion parameter from a fixed gun-launched impulse to a variable continuous rocket thrust. By controlling the rocket motor's thrust profile (magnitude and duration), the system adjusts the projectile's velocity-time relationship to maintain kinetic energy within non-lethal bounds at close range while ensuring sufficient velocity retention at long ranges.
2Object-affected harmful factors
If the mass of the projectile is limited to maintain non-lethal impact momentum at close range, then the projectile can safely impact at close range, but the projectile has a low ballistic coefficient resulting in great loss of velocity at longer ranges
Solution Approach 1:
The rocket motor dynamically compensates for the low ballistic coefficient by providing continuous thrust during flight. This active propulsion counteracts the increased drag effects on low-mass projectiles, maintaining velocity throughout the flight trajectory and ensuring effective performance at long ranges without requiring increased projectile mass.
Solution Approach 2:
The system replaces passive ballistic trajectory (relying solely on initial gun launch velocity and projectile mass) with active rocket propulsion. This substitution allows low-mass projectiles to overcome atmospheric drag and gravity more effectively, maintaining velocity and kinetic energy throughout the flight path without increasing mass.
3Length of stationary object
If a conventional gun-launched projectile uses fixed propulsion to achieve long range, then the projectile can travel long distances, but the impact momentum exceeds lethal thresholds at close range or insufficient at long range
Solution Approach 1:
The rocket motor provides dynamically adjustable thrust that varies during flight based on range and kinetic energy considerations. For close-range threats, the system limits thrust or shuts down early to maintain non-lethal impact momentum. For long-range threats, the system sustains thrust longer to maintain velocity and kinetic energy, ensuring effective impact momentum at extended ranges.
Solution Approach 2:
The rocket motor system incorporates feedback control based on flight distance and kinetic energy measurements. The control system monitors projectile position and adjusts thrust magnitude and duration to maintain kinetic energy within non-lethal bounds at close range while ensuring sufficient energy for long-range effectiveness. This feedback mechanism allows adaptive propulsion tailored to specific engagement ranges.
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 cartridge maintains kinetic energy below lethal thresholds across varying ranges by balancing thrust, mass loss, and flight time, ensuring effective non-lethal performance at both short and long ranges through tailored thrust profiles and propellant configurations.
Implementation Method 1
A non-lethal projectile is disposed in the casing forward of the propellant and has a central longitudinal axis. The projectile includes a soft nose and a variable thrust, solid propellant rocket motor disposed aft of the nose.
Data Source
AI summary
A gun-launched, non-lethal, anti-personnel projectile includes a variable thrust, solid propellant rocket motor. The rocket motor has a variable thrust profile that maintains a substantially constant kinetic energy of the projectile below a lethal threshold from a range of about 5 meters to about 400 meters.