Note that if the handle uses an open-ended hook as a pivot point, going way past 90 degrees may not be possible.īoth of these optimizations are intended to allow making C as short as possible, which in turn makes the wippe as light and as manageable as possible. Maximize the rotation angle of the wippe handle (BC).Make B as short as possible for the chosen draw length.There are two factors you can adjust to do this: The one thing you definitely want to do is maximize the advantage in leverage the wippe provides. Probably the easiest way to find out the correct dimensions is to test different lengths using a CAD program or even cardboard templates. The problem is that there's no simple formula for determining the dimensions of these parts. If the trigger is spring-loaded or correctly balanced, it will also rotate and lock the nut in place automatically, making cocking the crossbow smooth and easy.īesides these potential caveats, correctly selecting the length of A and B can be tricky. This allows the bowstring to automatically rotate the nut back to shooting position. The Medieval Crossbow: A Weapon Fit to Kill a King by Stuart Ellis-Gorman (Goodreads Author) really liked it 4.00 Rating details 2 ratings 2 reviews The crossbow is an iconic weapon of the Middle Ages and, alongside the longbow, one of the most effective ranged weapons of the pre-gunpowder era. The wippe must be able to push the bowstring past the nut.This can be avoided by keeping the maximum angle clearly below 45 degrees. If the angle between the stock and A is too obtuse, the wippe will be unable to push the bowstring back towards the lock rather, it just pushes the it against the stock.If the distance between D and E is not sufficiently long, the top of the stock prevents the wippe from moving through it's entire range of motion.When designing a wippe, there are a number of potential caveats that need to be avoided: (D) steel loop around which wippe's hook rotates, attached to the stock using bow irons.(A) rotating part of the wippe which pushes the bowstring towards the lock.The diagram below shows wippe operation in three distinct phases and illustrates some of these key design principles: The core parts of the wippe are shown in the below pictures:Īlthough the wippe looks deceivingly simple, there are several caveats you may run into while making one. In addition the front end of the crossbow has to have a metal loop, around which the lever's metal hook rotates. Wooden part pivoted to the wooden lever using the steel axle.Therefore this article puts much emphasis on wippe's operating principles and the issues that may arise during use. While making the wippe parts is easy, designing it so that the lever operates just right with a given crossbow is not. However, cocking a bow with a wippe is much faster than with a cranequin or a winch. A wippe-operated crossbow is somewhat slower to cock than a crossbow cocked by hand. Up to a point lengthening the lever allows even stronger crossbows to be cocked. Cocking a ~300 pound crossbow with a wippe is very smooth and easy with a lever that's only 80cm long. A wippe made of wood is also much easier to manufacture than a goat's foot lever, which can only be made by blacksmith. Unlike goat's foot lever which pulls the string to the nut, wippe pushes it there. It is basically a much simplified version of the goat's foot lever. Wippe is an simple wooden lever that can be used to cock a crossbow of moderate strength.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |