Hi All,

To continue the discussion from a couple of weeks back... (I have been away).

My dad (Nick) is going to write a more detailed article to go in the gray mag, those of you who had read about the floppy flywheels prior to the article in the association mag he did write something in the Bristol Club mag year ago (ish).

I will be doing a full 3D CAD model of the modified flywheel for the purpose of graphics for the mag and to create a full set of drawings.

Malcolm Watts asked if a clutch plate had been considered. For the purpose of the seven engine and the masses involved it was important to ensure the natural frequency of the spring & mass system was significantly below the speed the engine could run, even on a very low tick over. The clutch plate is much stiffer than the strips dad uses, it is possible the natural frequency would be too high.

I was discussing the idea of the floppy flywheel with one of my university lecturers, he was fairly sure he had seen a similar device possibly on a Lanchester which he was fairly sure used something along the lines of a spring steel plate, however the mass of the flywheel would have been much higher so the natural frequency would have been suitable.

Steve Martin commented on harmonic dampers as used on modern car engines. In these the spring in between the mass and the shaft acts in the rotational direction to damp out torque vibrations. The springing in the floppy flywheel acts in the axial direction but is stiff in the rotational direction but essentially the idea is the same.

Steve also commented on the danger of the flywheel falling apart, one of the early versions did this in our opal at about 65mph and went eccentric. The flywheel was also lightened so the starter ring was the largest diameter part of the flywheel, it machined a good notch round the inside of the bell housing and made an incredible noise!!!

Regards

Rob Beck

Rob,

as one VERY interested enthusiast, I look forward to your information, thank you to both you and your Dad !

kind regards to you both,

Malcolm

Thanks Bob,

Now that I am back from a weekend of A7 touring in Dorset it looks like you have committed me to sort some details out.

Nick.

Dr Frederick Lanchester designed a couple of devices for reducing torsional vibration stress in crankshaft systems, which are used today in marine diesel engines and some cars. The first was a flywheel with a loose rim, which can move independently of the driving portion and is connected to the driving portion by a spring/s as in the Doxford-Bibby and Geislinger damper/coupling, which are oil damped. The second, you either like or loath, consists usually of 4 shafts, 2 at each end of the engine, each with a counterweight running at twice engine speed. These can found on 4-cylinder inline and 8 and 10 cylinder vee marine engines and when things go wrong it spells disaster big time especially if the gears aren’t timed correctly. These can also be found on some cars like Mercedes and Saab where the sales people make a big play on the Lanchester balancer-for me the less moving parts the better. Dave.