Model Maker: Volume 1, Issue 3 – February 1951

MOE incorporaling Mm a K THE MODEL MECHANIC & MODEL CARS VOLUME 1 IN THIS ISSUE: Daughter : Making a Micrometer : Scenic Effects for Model Buildings An ETA Engined Speed Model Car Cornish Harbour : : Trams and Tramway Modelling : : : Vice Clam Mould : : On the Right Track eal ee x, . my. ji TE : * 7 A Model of Pharoah’s Se 5 es : : A Model Self-Oiling Lathe Centre Australian Model Car Championships Load Waterline Calculations B.R.M. Prototype Car : Building a Skirrow Midget Model Car Grindstones Driven by Lathe Motor : New Model Car Rail Track & Novice Starts Model Engineering ee Gear FEBRUARY 1951 NUMBER 3 (New Series) “— : : Coastal Sailing Barge New ‘00’ Series : : Braine Features MODEL MAKER The Braine Automatic Steering ; i Z_TENSION’ COR a Lo Tes | sek ! 7 > ay – << el S Teae A y* \ = DRILL & TAP 6BA. SPINNA KER Uv RADIUS teuilout e BEFORE the advent of the automatic steering gear the model yachtsman carried . a pocketful of swing rudders of varying weights which he changed to suit the prevailing wind. Under these conditions the steering of a model was a very haphazard affair. The Braine Steering Gear, conceived by Mr. Braine of the M.Y.A., has changed all that and is now al- most universally used. A few years ago a Swedish model yachtsman invented a pivoted vane steering gear which has a growing following. It consists of a light vane attached to the rudder head actuated by the wind, the movement being controlled by rather a complicated arrangement of links, too complicated for the novice to worry about. The Braine gear consists of a quadrant (Fig. 14), a pair of pulleys (Fig. 13) and two quadrant hooks for the steering lines. Fig. 23 shows a plan view of the complete gear when fitted. Note the crossed lines which is an essential feature of the device. The principle of the gear is as follows: — As the wind on the mainsail exerts pressure on the main boom (to which the lines are attached) the windward line, being crossed over, pulls on the lee arm of the quadrant. The quadrant being fixed to the rudder head pulls over the rudder blade thus preventing the yacht from running up into the wind. When the model is put about on the opposite tack the slack lee sheet becomes taut and operates the rudder in the opposite direction. The quadrant has a series of holes drilled along the arm which enables the leverage to be altered by inserting the quadrant hooks in different holes. From this it will be seen that the farther towards the extremities of the arm the hooks are placed the greater the leverage and, therefore, the greater the angle of the rudder blade. on a pintle bearing. v3 4, iy: Ae enk i QUADRANT 5! | 4 HOOKS. tee RUDDER POST { Wp i FOR . | | : Ses rc H F F oni 694 + RR eae = ——. past 9 sell rire ce me SKEG PLATE. to its central position, which it cannot do if any friction or binding is present. Only practice will enable the novice to use the gear to its best advantage, but the following hints will help him to grasp the main principles. If the model keeps off wind when it falls light the elastic adjustment is too slack. If, under the same conditions the model turns into the wind, the elastic is too tight. When the wind freshens and she keeps off the wind, less leverage on the quadrant is required so move the hooks nearer to the centre. If the reverse, more leverage must be applied by moving the hooks towards the end of the quadrant arms. When the exact settings have been found they will be correct for all time, so make notes of the various settings under different conditions. If you can enlist the services of an experienced fellow yachtsman so much the better. It is well to remember that all adjustments should be slight, or progressive, until the correct setting has been found. Do not be discouraged by the erratic performance of your model at first, such as the keel out of line, any tendency to poor steering performance is probably due to your inexperience. There is only one condition under which the Braine gear is not used. That is beating, or sailing into the wind. A well built model will, under these conditions, steer by the trim of the sails. When beating slack off the steering lines and attach the beating sheet to the main horse. It is of the utmost importance to see that the rudder be free, but not slack, in its tube, and for this reason the heel is fitted pri 4 A rubber centreing cord is fitted, which is adjusta ble as to tension, to ensure that the rudder always returns 154 February 1951 Gear & how to use tt “LADY BETTY” 36 in. PART V. RESTRICTED CLASS YACHT BY SHIPWRYGHT FIG 13. DECK PULLEY & DECK PLATE. FIG. 14. QUADRANT & RUDDER ASSEMBLY HOLE FOR ELASTIC Above : The completed ''Lady Betty'' Yacht. Left : A typical 6-metre showing the Braine steering gear in operation. Although not strictly connected with the Braine + _ = gear there is a device which is part of the steering apparatus of a model yacht. This is known as the beating gye. This enables a model to go about, or change course, after reaching a pre-determined posi- tion when making alternate short and long legs up the course. It consists of an adjustable cord with elastic tensioning (Fig. 24). One end is attached to the outboard end of the main boom, the other end to an eye on the gunwale on the weather quarter. To operate, adjust the elastic so that it is fully stretched when the sail pulls on the beating sheet. The gye then gradually exerts pressure on the main boom until the boom swings over and the model goes about on the opposite tack, holding that tack until she reaches the shore on the next leg where she is put about once more by hand. If this action takes place too quickly the elastic tension is too tight. Should she fail to go about before reaching the shore the elastic is too slack to exert the necessary pressure on the boom. Here again practice is necessary for its successful operation, but it is one which will often win a close race when operated by an experienced skipper . 155 Sv STEERING LINES TENSION corD FIG.23. PLAN OF BRAINE STEERING GEAR. (DIAGR AM ONLY.)