ORIGINAL: Ameisenbar

Part of the ingenuity of the original design by Dornier was that they could use a pair of identical engines, eg not a handed pair like a normal twin would have. This gives opposite rotation as seen from the front, and needs a pusher propellor. It also makes maintenance easier, eg spare engines are all the same. Luckily they never got enough into service for that to matter anyway. With both engines going the torque reactions cancel out. If one fails there is no assymetrical thrust and only a normal amount of torque reaction, which will be left for one of the engines and right for the other.

For a model I am not sure that this is too important. We are not overpowering our models quite so much as the full size.So although the counter rotating props would be nice to have, if the pusher one is not readily available I wouldn't worry, at least for the electric guys. Torque effects should be no worse than if a single engine in the front is providing all the power. Of course with IC engines reversing the direction is not such an easy option.

I asked a while back if anyone knew what all the servos were supposed to be for. Having studied the comic book in more detail I have now figured it out. They are allowing for an ignition switch servo for the front engine, and when you add the rear engine, that gets one too. This is despite the fact that in the little picture the rear engine looks rather like a glow fourstroke. Anyway, these days, I would suggest that rather than using a servo to push a switch, one should use one of those little optically coupled switches made for the job...lighter than a servo and switch, and less prone to failure from vibration.

John