Pioneering
Catapult Project
The Project: Each Patrol is divided into two-man
teams. One team will assemble the trestle and the other team the side braces.
Notes on Trestle :Assembly Be sure that each patrol follows the diagram carefully.
Make sure that all lashings are tight. Wrap working end around a sturdy stick
and pull each lashing tight. Lash the diagonal braces high enough on the legs
so as not to interfere with the function of the thrower.
Notes on Side Braces Follow the diagram carefully. Be sure to square lash butt
ends. Be sure to frap square lashing to facilitate twists of spars.
Set Up Raise the trestle when ready. Transom and ledger should be parallel to
the ground. One team should now lash the side braces to the trestle while the
other begins assembly of the thrower.
Lash lower trestle side braces to outside of trestle legs first. Tilt the trestle
back about 15 to 20 degrees from vertical. The Project Instructor should sight
check each catapult. Lash the upper trestle side braces making sure trestle
legs are parallel when viewed from the side. After the side braces are lashed
into place, the tie piece should be force-wedged into position according to
the diagram.
Notes on the Thrower Follow the diagram carefully. Note which spars are lashed
to the top side and underside of the arms.
Critical Note: Before lashing cross pieces on the thrower arms place pivot crosspiece
into position on trestle assembly. MARK THE PIVOT CROSSPIECE SO THERE WILL BE
ONE INCH OF CLEARANCE BETWEEN THE THROWER ARM AND THE TRESTLE LEG ON EACH SIDE.
There must be enough clearance so that the thrower arms do not hang up between
the trestle legs. A one-inch clearance is absolute minimum.
After the cross pieces have been lashed to the thrower arms one team can prepare
the basket while the other lashes the
counterbalance into position.
Notes on the Basket If the Basket is too deep, the object being thrown will
remain in the basket. If it is too shallow the object will roll off.
After the thrower assembly is finished, raise it into position on the trestle
assembly according to the diagram.
Rigging: One team should now loose-lash the pivot cross piece into position
while the other attaches the two pulleys, shown on the diagram, to the ledger.
Two lines are now run from the counterbalance through the pulleys to the rear
of the catapult.