hopper

[David Gundling]

Message text written by INTERNET:discussion at nsrca.org
>I am with you on this one. Running a Y.S. 140 without a hopper tank
and than changing to a hopper tank setup I have found that I could lean
the engine by 3 clicks on the needle. Going back to just a main tank
without the hopper the engine was set to lean. This should prove that
it is of benefit to run a hopper tank for any set up with the main tank
near the C.G., crankcase pressure or pipe pressure, 2 stroke or 4 stroke.
<

Karl,

Never played with a hopper tank, however, I suspect that the discussion has
apparently missed the friction factor. There is friction in moving fuel
through a small tube. The hopper tank reduces that friction in the vertical
or any nose up attitude. Wonder if the same effect could be achieved by
making a fitting to allow larger ID fuel tubing to be used? I have measured
muffler pressures with a manometer  as high as 1 psi. That should be able
to lift fuel more than a foot or two even acounting for G loads during
maneuvers. Could it be that suction is not capable of overcoming both
gravity and the friction force at the present high fuel flow rates?

Dave
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