[python] Re: Leverarm Python - @25hz: do you know of studies supporting your assesments?
- From: Ronald Hongsermeier <rwhongser@xxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Thu, 08 Nov 2007 12:13:37 +0100
Hoi 25hz / other Listies,
This is a little more off topic, so please look by it if boats and being
physically challenged don't concern.
> > can keep up with that at max effort. Adding a 2nd leg is less than
> > twice as efficient because the body can't fuel both to 100% capacity.
> > Add arms to the equation, and there's even less efficiency gain ....
>
My long-term interest in pedal powered watercraft fuels this comment. /*Greg,
if you're still following the list, send me a smile or something ;-) */
I haven't had my hands on a mirage drive system from Hobie, but depending on
whether it is so-construed or could be modified to do so, one could drive it as
below described.
This seems to say that a system that could alternately use one or the other of
the legs (possibly adding the opposing arm just to stay loose?!?) might be the
best for a system, say for powering a vehicle for a long day. Harry Bryant, a
canadian boatbuilder who's written quite a few articles for Wooden Boat, once
said something to the effect that the simple back and forth motion of his
trailing fin drive was more efficient than using a cog-system to drive it. I
don't know if this is true, but it could point to an advantage for a 24-hr. run
if the necessary watts to keep the system moving above the necessary pace could
be maintained with one leg.
I often see bicycles here in the area modified for someone who has a serious
leg injury where the "lame-side" pedal is on a free running shaft a short
radius from the bb. This evidently produces a massage effect that on the one
hand keeps the crotch area from getting abnormally abraided by keeping the
motion evened out on both sides and also moves the "passive" leg, increasing
its circulation. Whether the lame leg is totally passive or can actually
provide some motive power depends on the length of the lever arm of the
shortened pedal arm to which the "lame pedal" is attached...
On re-reading this I notice that it suffers in clarity a bit by mixing the two
contexts. Sorry.
Ron
> -----Ursprüngliche Nachricht-----
> Von: python@xxxxxxxxxxxxx
> Gesendet: 08.11.07 02:46:00
> An: <python@xxxxxxxxxxxxx>
> Betreff: [python] Re: Leverarm Python - @25hz: do you know of studies
> supporting your assesments?
>
> I found it in a Google search while looking for somethinga little different
> in topic. I don't think those results are counterintuitive though. Most
> people close their eyes and see someone pedalling with their legs and
> pedalling with their arms. They don't even think about all the back,
> stomach, shoulder, chest, glute and hip muscles being employed to stiffen
> the body so force can be applied with all 4 limbs. On top of that, the body
> is no different from any other system where the more parts doing work, the
> less efficient the overall system is. While the body is a magnificent
> machine, it still has to answer to the laws of physics.
>
> > > Actually, the more limbs used, the less efficient it gets. The most
> > > efficient system is using one leg. The cardio and circulatory system
> > > can keep up with that at max effort. Adding a 2nd leg is less than
> > > twice as efficient because the body can't fuel both to 100% capacity.
> > > Add arms to the equation, and there's even less efficiency gain ....
> >
> > 25hz,
> >
> > that might be true, but it's somewhat counterintuitive. Then again, HPV
> > helicopters and planes built by university labs, where every little
> > efficiency gain is essential, are all legs only driven, afaik. Anyway, do
> > you know of studies supporting your assessments?
> >
> > Marek
> >
> >
> > Marek Möhling
> > Naunynstr. 82
> > 10997 Berlin
> > Tel: +49 30 627 341 29
> > Fax: +49 30 484 988 218
> >
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