4. The Fuselage, Front Section I

Figure 9 shows the mounting for the engine crankshaft. A 2 1/2" girder 15 is bolted to 5 1/2" x 2 1/2" flat plate 16. The flat plate extends one hole beyond the girder. A 2 1/2" triangular flat plate 17 is bolted onto the front of the girder and a crank 18 bolted to the rear of the triangular plate provides a journal for the crankshaft. A washer should be used between the crank and the triangular plate in the centre hole of the crank.

Bolt a reverse angle bracket (Figure 11, 22) to the underside of the flat plate, through the central hole of girder 15. Bolt the flat plate to the slot of the reverse angle bracket, so that it can be adjusted if needs be. The two holes of the bracket will rest in the angle of the 1" x 1/2" angle bracket (Fig 6, 4) in the engine cowling.

Figure 10 shows the addition of a second girder and triangular plate along the same lines, but with no crank, to strengthen the mounting for the crankshaft. A threaded pin 19 also gives a little support at the top hole of the triangular plates. The engine and motor have also been added.

In a real rotary engine, the crankshaft is fixed and the engine rotates around it. In the model, the crankshaft rotates with the engine and the airscrew all of a piece. Because of the weight of the engine, it's important to make sure the mounting is secure and the shaft moves as easily as possible in the bearings, given that the weight of the engine will tend to pull downwards on the crankshaft. Of course, when it reaches the right speed in rotation, the downward pressure on the crankshaft is eased as centrifugal force directs the pressure outwards instead of downwards.

In the model, a Meccano M0 motor is used to drive the crankshaft. The gear train consists of a 13-tooth pinion 20, from the Meccano No 1 clockwork motor, and a 50-tooth gear wheel 21. The motor requires rather more power than is provided by the battery packs which are usually sold with it, and modellers may wish to use a more powerful motor and devise a different gear train. In the model, an 18-volt 1.5A controllable transformer was used to provide a powerful boost on startup, and then the motor was 'blipped' while running, lessening and increasing the power in short bursts, much as the pilots controlled the speed of the original engine. But I would recommend using a more powerful DC motor and building a gear train to suit. Some possible areas for improvement are discussed at the end of these instructions.

Figure 11 shows the underside of the front fuselage with the undercarriage bolted in place. This will have to be done before the front fuselage is completed. Note reverse angle bracket 22 which connects the engine cowling to the front fuselage as previously described.

Two 2 1/2" flat plates 23 are also bolted to flat plate 16, set back three holes from the front edge of flat plate 16, as shown. These will provide a base to which the lower wings are bolted later.

All bolts 24 have a washer between flat plates 23 and flat plate 16 which tilt flat plates 23 slightly upwards, to assist the lower wings in obtaining the correct upward tilt.

The engine can now be put onto the crankshaft, making sure there is room for the airscrew to fit onto the shaft as well, and the engine cowling bolted in place onto the reverse angle bracket.

Check that the motor will drive the engine, and adjust the cowling to make sure nothing impedes the rotation of the engine cylinders and the airscrew. It should be possible to tighten the grub screws in the flanged wheels of the engine crankcase through holes in the engine cowling.