Meccano Society of Scotland
The Challenge this year was to construct a Trebuchet. Click here for the detailed rules
In the event there were 5 entries. Two of these did not fall within the rules. One was spring operated. By definition a trebuchet was weight operated. The Oxford English Dictionary defines a trebuchet as "a machine for projecting missiles against defences". While this is a necessary condition of being a trebuchet, it is not sufficient to completely define the machine. The rules originators did not consider it necessary to include a "no springs" rule, it having been assumed that the weight operated condition would be well understood by entrants. The other entry that did not meet the criteria was one which had a sling attached. As it was 15½" high and the sling was attached at the top, in operation it was going to be outwith the 15½" arc defined by rule 4.
From left to right in the general picture below are:
- Douglas Carson's entry. Highly ingenious design with the weight falling vertically and activating a lever system which caused the arm to flick over at high speed. Projected the missile further than anyone else but unfortunately disqualified as the sling on top did not operated within the specified 15½" arc.
- Bill Jack's entry. A conventional design. Probably had the greatest activating weight.
- Bobby Middlemass' entry. Spring operated and therefore not within the rules.
- Robert Jones' entry. Another conventional design having the pivot point on the projecting arm very close to the weight.
- Rod Bessent's entry. Very well engineered machine with a geared wind up device for the weight. Projecting arm at right angles to arm bearing weight. The overall winner.
In the event each machine was required to project three missiles:
- A matchbox with a small number of ball bearings
- A matchbox filled with ball bearings
- A practice golf ball (i.e. a hollow plastic sphere with a perforated surface).
The results are shown in the table below:-
|Entrant||DISTANCE PROJECTED (inches)|
|Light Matchbox||Heavy matchbox||Practice golf ball|
For some reason the performance of Robert Jones' entry with the golf ball was not recorded. Douglas Carson's sling would not hold the ball and his machine therefore did not project it.
Rod Bessent was the overall winner with the missile specified in the rules. Interestingly Bill Jack's machine outperformed it when the golf ball was used as a missile. Douglas Carson's machine was so much better at projecting the matchbox that one is left wondering if a better design within the rules might have been a shorter projecting arm with a sling to bring the operating arc up to the specified arc. Or was his success due to the ingenious vertically falling weight mechanism referred to earlier?