Crossbow Elongated Draw Length and Rearward String Release
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Solution Overview
Problem
Conventional crossbows have limited draw length and power stroke, requiring high draw weights to achieve suitable arrow speeds, making them cumbersome and difficult to cock.
Innovation Solution
A crossbow design with an elongated draw length and string compression levers that allow for a longer power stroke without increasing overall size, reducing draw weight and enhancing safety and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the draw length of a conventional crossbow is increased to achieve a longer power stroke, then the arrow speed and kinetic energy improve, but the crossbow becomes heavier, bulkier and more difficult to handle
Solution Approach 1:
The patent relocates the string release from a forward position to a rearward position near the shooter's face, effectively utilizing the rearward space along the stock length dimension. This dimensional reconfiguration allows the power stroke to extend the full length of the stock rather than being limited to the forward portion, achieving longer draw length without increasing overall crossbow dimensions or weight.
Solution Approach 2:
Instead of extending the crossbow forward to increase draw length, the invention inverts the approach by placing the string release at the rear end of the stock near the shooter's face. This inversion allows the string to be drawn backward through the stock, utilizing the previously unused rearward space to achieve elongated draw length without making the crossbow bulkier.
2Speed
If the draw weight of a conventional crossbow is increased to achieve suitable arrow speeds with limited power stroke, then the arrow kinetic energy improves, but the difficulty of cocking the crossbow increases
Solution Approach 1:
By extending the power stroke in the longitudinal dimension of the stock, the invention reduces the required draw weight to achieve the same arrow kinetic energy. The longer power stroke allows energy to be applied over a greater distance, reducing the force (draw weight) needed while maintaining the same work output (kinetic energy), thereby making cocking easier.
3Device complexity
If the string release is positioned forward in conventional crossbows, then the mechanism is simpler, but the draw length is limited and the string is in front of the shooter's face when aiming
Solution Approach 1:
The patent moves the string release along the longitudinal dimension of the stock from the forward position to the rearward position near the shooter's face. This positional change in the longitudinal dimension allows the draw length to extend the full length of the stock while keeping the release mechanism itself relatively simple, avoiding the need for complex mechanical modifications.
Solution Approach 2:
Instead of having the string release forward and the string extending backward, the invention inverts the arrangement by placing the string release at the rear end near the shooter's face, with the string extending forward through the stock. This inversion resolves the limitation of forward string release while maintaining mechanical simplicity.
Data Source
AI summary
A novel embodiment of a crossbow (10) includes an elongated draw length and a rifle-type stock (134) with a tubular barrel (106) designed to shoot standard three-fletch arrows (120) with a three-blade hunting tip. When the main string (105) of the crossbow (10) is fully drawn and cocked, the string compression levers (110) that are pivoted so that the pulleys (113) on levers (110) engage the string (105) and deflect the string (105) toward the barrel (106) until the string compression levers 110 rest against the side of the barrel (106). The crossbow (10) has a draw length significantly longer than the draw length of a conventional crossbow of the same overall size, thereby providing a larger power stroke with less draw weight. In the other embodiments, the crossbow (20, 30) may include a barrel (106) with rectangular cross section for shooting shot filled sabots for bird hunting, small game hunting or trap shooting or a barrel (106) with a circular cross section for shooting paint-ball filled sabots for paint ball games.