Robin van Spaandonk wrote:
six "power strokes" per cycle
As well as multiplying the power strokes, you also multiply the sticky points.
Yes, of course. I think you got almost there - to finding a glimmer of
the ultimate tactic to push this to the limit. What we need to add into
the explanatory mix, in order to understand why this is not just an
exercise in grade school arithmetic is the this:
You have a certain amount of stored angular momentum in any flywheel,
based on its mass - the purpose of which can be labeled as "continuity"
or "smoothing out" the bumps, meaning that it is designed to average-out
the ups and downs of incremental torque and incremental drag, at the
various stages of one revolution. Flywheels are absolutely necessary for
low RPM devices like the old steam engine - which had plenty of both
peak incremental torque and peak incremental drag.
*Peak drag* per any segment of one revolution (but NOT net total drag)
would seem to be the all-important variable for flywheel mass. You can
lower the peak of each of the two variables (boost and drag) by adding
more cylinders in an auto engine, for instance, and this decreases the
necessary flywheel size. Same with the number of EMILE "arms" ? Glad she
isn't named Helena.
A rule of thumb for flywheel mass in low RPM situations as witnessed by
the single cylinder engines of 80 years ago (which had 500 pound
flywheels) and this may also be a function of the Aspden effect - is the
larger the better - if you can start it. Modern automobiles do not have
a big flywheel because they have effectively lowered 'peak drag' with
more cylinders - and also they require the quick variability of engine
speed for acceleration, so they sacrifice the advantages of a flywheel,
if any are truly a significant part of the Aspden effect.
When drag can be reduced from its peak level - even if the average is
the same, one can effectively use lesser weighted flywheels. This is as
much an educated guess as a well-researched finding. But so long as you
do not need to vary the speed of the device quickly, and if you can
start it up by hand without needing a larger starting boost, then we
would be talking about matching the net angular momentum against the
highest level of drag, ERGO when you divide by three - even though the
net drag is the same - the peak is one third less and the flywheel mass
can be reduced correspondingly without gearing. For EMILE this might be
the difference between a 20 kg flywheel and a 60 kg one. I have no idea
what is easily doable in that circumstance - but even with the old model
adding a 60 kg flywheel and ditching the solenoid - could seemingly be
done in a day or so.
Bottom line - yes you have more sticky points with more arms - but the
peak drag is much less even though the average drag is the same - and in
order to avoid gearing, you can use a lighter flywheel with the design
change --- or --- why not try the proverbial "super-size-it" BF-Flywheel
first? Here's on that granny sez - you can if if you carry it out:
http://www.oldengine.org/members/diesel/Scrap/Scrap12.jpg
That is my take on the situation - and again it would seem that the more
ramps and arms which are provided - the lower the mass of and effective
flywheel size - but at some point you would run into the problem of eddy
heating of the magnets and NIBS have a low Curie point.
Maybe IF the thing is really OU (big grin) then at the same time, it
will be self-cooling as well - but as I am (figuratively) from Mizzou,
and as they say in the South - show me!
Jones
