Click on images to view larger picture.
The WAF-3.5 was made by Walter A. Frisch of Berlin-Lubars in the mid-1950ís. Frisch had begun making model engines in 1953 with his 1cc WAF-1 diesel which remained in production for about 5 years. This engine was given a favourable review in British magazine, Model Aircraft, of December 1953.
Regarding the 3.5cc pictured here, in 1954 Frisch was encouraged by the sales of the WAF-1 to consider expanding the range. He made a run of just ten examples (good Germanic, metric thinking) of a proposed 3.5 cc model for testing and to obtain some modellerís impressions. The project never seems to have progressed beyond this stage, making this example a rather rare engine.
Visually and structurally, it is pretty much exactly like a scaled-up WAF-1, the giveaway being the extended, brass venture intake and the "3.5" embossing on the left side of the crankcase. It retains the characteristic "assymmetric bend" comp screw of the WAF-1, the bend at one end presumably being intended to eliminate ambiguity regarding the comp setting. Internally, the porting arrangements are identical to those reported in Model Aircraft for the WAF-1.
Bore and stroke of this motor are 15.6mm x 18.0mm, giving a capacity of 3.44 cc. For purposes of comparison, the last photo above shows the WAF-3.5 posed beside a 1cc ED Bee Mk II which gives a good indication of its gigantic size. The long stroke of the WAF results in the engine being unusually tall for its capacity, just like the WAF-1, a factor which gives it a rather old-fashioned appearance and may have told against it in potential sales terms. At 213 gm (about 7.25 oz), it is a bit porky in terms of weight, much of which is in the very heavy cylinder. However, it runs very strongly and is easy to start, as is reported for the 1cc model.
Thanks go to Adrian Duncan for the pictures and story.