rickharris
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- Jan 19, 2008
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I woke this morning with a nagging thought I cant get out of my head. I am sure this is a silly idea but cant see why.
From what I read most people in this business dont use live steam for some good reasons most are using compressed air. Compressors are noisy and not very house friendly.
If you need say 25 Psi to run your engine this could be generated by putting a weight on a piston in a cylinder.
OK:
Say a small wobbler such as Elmers has a swept vol of .32 cu inch (about 5 cc) we want to run it at 200 RPM. Assuming no losses/leaks(!) it will use some 1000 cc of air a min (1 ltr).
As pressure is related to surface area if we put a 1 lb weight on a piston 4 inches dia it will generate 12.5 PSI so 2 lbs will produce about 25 PSI 4 lbs about 50 PSI.
A 1 litre volume of dry air under 25 PSI would need to start out at 1.26 ltr (I think!) and would last for about 1 min. (5cc swept x 200rpm).
Recharging the system would only call for lifting the weight. So making such a structure to charge say 5 ltrs to get a run of 5 mins doesnt seem too difficult.
My mental picture is of several tubes to make up the 5 ltr or what ever you choose kind of bicycle pumps bonded together with the weight on the top. By using a cup valve as in a bike pump sealing is easier and accuracy of build less critical.
Of course a suitable 5 ltr vessel could also be used its not that big, about a gallon. A wider vessel would correspondingly require less weight.
Am I totally missing the point and getting it all wrong?? wouldnt be the first time
From what I read most people in this business dont use live steam for some good reasons most are using compressed air. Compressors are noisy and not very house friendly.
If you need say 25 Psi to run your engine this could be generated by putting a weight on a piston in a cylinder.
OK:
Say a small wobbler such as Elmers has a swept vol of .32 cu inch (about 5 cc) we want to run it at 200 RPM. Assuming no losses/leaks(!) it will use some 1000 cc of air a min (1 ltr).
As pressure is related to surface area if we put a 1 lb weight on a piston 4 inches dia it will generate 12.5 PSI so 2 lbs will produce about 25 PSI 4 lbs about 50 PSI.
A 1 litre volume of dry air under 25 PSI would need to start out at 1.26 ltr (I think!) and would last for about 1 min. (5cc swept x 200rpm).
Recharging the system would only call for lifting the weight. So making such a structure to charge say 5 ltrs to get a run of 5 mins doesnt seem too difficult.
My mental picture is of several tubes to make up the 5 ltr or what ever you choose kind of bicycle pumps bonded together with the weight on the top. By using a cup valve as in a bike pump sealing is easier and accuracy of build less critical.
Of course a suitable 5 ltr vessel could also be used its not that big, about a gallon. A wider vessel would correspondingly require less weight.
Am I totally missing the point and getting it all wrong?? wouldnt be the first time