Model Flyer February 2000 compressed air regulator valve article

[Nigel_M]

I have part 2 of an at least 3-part series on compressed air engines by Norman Fallows which, I presume, ran from December 1999 to Febuary 2000, because Part 2 is in Jan 2000 issue of Model Flyer. The Part 2 which I have mentions a regulator valve which Norman designed and built and states the design is described in Part 3. I'd like to read that if possible and have fingers crossed it includes at least a GA diagram.

My interest is not so much in the compressed air engines but I want to find if anyone has developed a constant pressure regulator suitable for our CO2 engines. To the best of my knowledge, most if not all CO2 model engine regulators are simple flow regulators that only reduce the supply pressure by a constant proportion. For constant speed, the bane of CO2 motor operation, we need constant supply pressure to the motor which equates to constant gas pressure on the outlet from the regulator.

The design is well established - search on gas pressure regulator valve, Wikipedia is ok if a bit OTT - the design effort required will be to find a spring and suitable diaphragm areas that work at our sort of scales. It might not be possible ie practical within sensible weight limits. I wondered if this article might have made a workable design; it looks promising from a photo of the parts in Part 2 but the working pressures might be completely different.

Thanks

[Nigel_M]

I've sourced some pages from Feb 2000 but it is a short article whereas most in the series are quite long - I wonder if my source only copied info on the engine and not some other pages which describe the valve, as promised in the January article. However, the description of the February engine stated it used a different approach to regulating the amount of air admitted each cycle - a spring concentric with the pin on the piston crown. The spring would partially compress when opening the ball valve, and more so if the pressure bearing down on the ball is higher, making the effect in some way related to supply pressure. An interesting concept. So maybe the regulator description was deemed unecessary and dropped from the article?
I've also been reading Doug McHard's articles on compressed air motors which have some useful info. Perhaps most relevant is that his regulator weighed 20+ grams so is perhaps too heavy for many models. I will keep searching.

[SP250]

I seem to recall in talking to Mr Stefan Gasparin once, when he was over here, that he was about to bring out a servo controlled throttle valve for the GM 300 motor to use in RC models.  Maybe that would be a starting point Nigel if you can get details of it from the current guy selling Gasparin CO2 motors, or someone on here who owns one.
John M