Crank shaft OK

Yesterday picked up the crank shaft as it had a bit more testing to be done. All fine, so that’s really good!!
But the bearing that was on it had to be forced of it and need to be replaced. Now I was thinking of putting 3 new bearings on, so now I am forced to do, I am sort of happy that I don’t have to make decision anymore, its going to happen!

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Oil pump

Ooops, yes finished the pistons.

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Today I started cutting gaskets, for the oil pump and carburetor. Not sure about the gasket in the oil pump. Might be a little to thick and not getting the pressure high enough. Going to test the pump anyway and find out how it performs, before it goes on the engine.

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Also started cleaning the first cylinder. All looking good so far (see valve on the right).

Just an hour ago, got an email from Jack who sold me the engine. One of his friends saw my pictures and was surprised to see what looked like a gasket on the cylinder flange where it bolts to the crankcase.

He had always heard that this wasn’t done because the constant pounding would compress the gasket and cause loss of torque at the attached nuts and eventual failure of the studs. So checking that out….

5 min later,
Already had a reply from my propeller guy, who has a Velie:

A thin paper gasket, not more then .015″ (= .38mm) with sealant was common on low compression engines of that era. I used that with no problems for 100 hrs. Never┬ácompare modern aircraft engine methodology to antique engine methodology. There are many dissimilarities.
So yes that’s what I will do.

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Ordered the Propeller

I got some good references from other people in the US about Chad, so yes I got more and more confident he was the one that was going to make my propeller.

Today I accepted his quote, and ordered the propeller, made from Mahogany !!!

Next I started working on transferring money to his bank account, not that simple, but managed to get it done on the 13th of Nov !!!!

Propeller design

I asked Chad more questions about propeller design and the relation with the engine and the Bleriot:

Gert,

People misunderstand the relationship between a propeller design and engine rpm. It is only partly true, and only with clean modern airframes, that an engine should turn it’s maximum rated rpm in full throttle level flight (see below 1). For a fixed pitch prop this means it will run 2-400 rpm less during takeoff and climb when slow airspeed doesn’t allow the prop to unload. The misunderstanding comes from the idea that lack of maximum rpm is “throwing away performance” or that somehow the prop design is “wrong” is false. In the case of very high drag antique airframes this “maximum rpm” concept is even more utterly false.

Performance of propellers on antique airplanes is largely self governing. If the prop rpm is faster it means the primary load, the diameter is less. Lack of diameter is a critical failing in antique prop design because diameter is leverage and leverage is the most important aspect of good design for high drag antiques. If the prop rpm is lower it means that leverage is greater, an ideal situation for high drag airframes. These two scenarios happen to balance themselves perfectly, rpm vs diameter. They do not take into account other important factors such as planform, pitch, blade chord, airfoil and thickness however, and those become real issues of design for best performance. They are commonly referred to collectively as “the black art” of prop design. And I’m not going to go into detail about those here, except to say that they become the cumulative smaller issues that go into making a propeller great compared to having a so-so prop or worse, a club. The club will also fly the airplane by the way, but never well. For antique airplanes and engines, engine maximum rpm or engine over-speed is a critical loss of performance, while engine under-speed, low rpm, is not only acceptable but often results in a much better propeller/airframe/engine combination, provided that other factors (cumulative smaller issues as above) are not in error to begin with.

Lastly, some people may also not have the understanding, and maybe don’t have the experience. They insist on seeing a particular rpm number on their tachometer. They may (wrongly) believe that the perfect accuracy of a given rpm number is very important. It is not at all important if other factors are in error. In general it is correct on a clean modern airframe, but not on a very high drag antique airframes.

Chad

(1) Correct rpm is no indicator of correct prop design. Only that the overall load matches the engine.