After bumbling through half a dozen different designs for the new limb irons, this one seems the best of the bunch.  According to the computer model, the steel in it will have a volume of 12.55 cubic inches.  This should give it a weight of 3.55 lbs, which is 3/4 of a pound lighter than the limb irons that just failed on the old limbs.  All the steel used will be heat treated car spring material.

The round biscuit that can be seen on the underside of the top strap is 1/4″ thick and puts a lot of section directly where it is needed in the area of maximum stress.  A matching groove will be cut in the limb to accommodate it. The raised area on the surface of the top strap is where impact will occur against the curved pocket on the field frame.    That smaller separate piece of steel on the bottom will be pegged and then bound with an epoxy soaked Dacron whipping  onto the underside of the limb.  It will serve to both protect  the wood from the bite of the inboard bundle,  while its hook will help to keep the bundle from slipping off the heel of the limb.  This latter is not as much of a problem as it is with the outboard bundle because the twisting of this half of the spring serves to move the bundle up toward the limb tip;  but even so, it is good to have something to help control it when the limb goes into its bouncing routine at the end of the power stroke.

It is time to go and rest my head bone.   The old brain needs to sleep on all this awhile before we lunge ahead with anything new.  Making changes on a full scale catapult takes time.  It doesn’t exactly turn on a dime.

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