Pulley Projectile Launcher Drawstring Force Reduction
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Solution Overview
Problem
Projectile launchers, such as crossbows and slingshots, face challenges in achieving high firing speeds while requiring excessive force to draw the string, complicating the system and making it difficult for shooters to easily arm the launcher.
Innovation Solution
Incorporating a plurality of drawstring pulleys that reroute the drawstring to reduce the draw weight, allowing for a more efficient loading of flexible limbs with less pulling force, thereby increasing firing speed without sacrificing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the force required to load the flexible limbs is increased to achieve higher firing speed, then the firing speed increases, but the force required to draw the drawstring increases excessively
Solution Approach 1:
The patent introduces drawstring pulleys as intermediary components between the drawstring and the flexible limbs. These pulleys act as mediators that change the direction and distribution of the drawing force, allowing the shooter to apply less force while still achieving the necessary limb loading. The pulleys system distributes the draw weight across multiple contact points and reduces the mechanical disadvantage that would otherwise require excessive drawing force.
Solution Approach 2:
The patent utilizes the spatial arrangement of multiple pulleys to redirect the drawstring force through different dimensional paths. Instead of a direct linear pull on the limbs, the drawstring force is routed through multiple pulleys that change the force vector directions, effectively using spatial geometry to reduce the required drawing force while maintaining the same limb loading effect.
2Ease of operation
If drawing aids and let-off cams are utilized to reduce the force required to draw the drawstring, then the ease of operation improves, but the device complexity increases
Solution Approach 1:
The drawstring pulleys serve as simple intermediary components that reduce drawing force without requiring complex mechanisms. Unlike let-off cams that require intricate cam profiles and locking mechanisms, or drawing aids that may involve springs and levers, the pulley system achieves force reduction through simple rotational elements that guide the drawstring, thereby maintaining operational ease while minimizing added 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 use of drawstring pulleys reduces the force needed to draw the string, enabling faster and more accurate projectile firing while maintaining a compact and stable launcher design.
Implementation Method 1
The plurality of first and second power group drawstring pulleys are configured to reduce a draw weight of the drawstring
Implementation Method 2
a first flexible limb and a second flexible limb, each first and second limb having a first end attached to the frame and a second end. The first and second flexible limbs are in an unloaded position when the projectile launcher is undrawn and in a loaded position when the projectile launcher is drawn
Data Source
AI summary
A projectile launcher includes a frame and a projectile moves within a horizontal projectile plane and along the projectile axis. The projectile is fired from a front end of the frame. The projectile launcher includes a first power group at a first frame side. The first power group includes a plurality of first power group drawstring pulleys. At least one of the plurality of first power group drawstring pulleys is attached to the frame. The projectile launcher further includes a second power group at a second frame side. The second power group includes a plurality of second power group drawstring pulleys. At least one of the plurality of second power group drawstring pulleys is attached to the frame. The drawstring is configured to be routed at least partially around the first and second power group drawstring pulleys.