10-28-2010, 01:17 PM
Quote:When you add pulleys and increase the amount of draw length in the Hatra, the effect is doubled according to the mechanical advantage you assign to it.The draw-length of the Hatra design can clearly be lengthened -- Mike Lewis has restricted it (to 103/105 degrees) by the positioning of the rear stanchions, but these can be moved. (I have not measured the theoretical maximum.)
Quote:When you increase the amount of horizontal movement by adding an additional 15-20 degrees of movement to the Orsova design, you end up with a discrepency in performance between the two. Clearly the Hatra with only 105 total degrees of movement is at a disadvantage in range and velocity not only as the Orsova now has a greater usable rotational range.This is more tricky, as the Orsova design has a built-in restriction -- the bow-arms can only move within the range dictated by the vertical iron struts. (I have not measured this, but hopefully Nick based his kambestria -- the vertical spring-frames -- on the actual Orsova example.)
