[python] Re: some thoughts
- From: "Dirk Jan Luiting" <djl@xxxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Thu, 13 Oct 2005 23:44:57 +0200
Hi Oivind,
i think it is partly a good idea,
mounting a backfin behind the backwheelaxel should give you a correct moment,
good thought,
however i guess the turbulence behind the riders back ruins the effect of it.
and i guess mounting it higher you get other effects,
like side winds push your bike over?
maybe 1 backfin behind the backwheel just over the ground?
maybe 2 sidefins low to the ground behind the backaxel?
(the more behind the backaxel the better for the turningmoment)
(backaxel because the construction rotates around the contact the backwheel has
with the ground)
its also mainly a problem in the front, and there i try to solve it
its a bit like the driving wind is pushing me to the left so i correct it at
the spot.
a risk with such an active construction is destabilising overcorrections,
like when you get into a flutter (left, overcorrection to the right, even more
overcorrection to the left etc.)
but i am also counting on the rider input or damping factor :-)
hmmm, who is going to test such a system 50 km/h downhill, not me? (lol)
a backfin is always better, because it is an uncomplicated passive never
overcorrecting system.
but here we dont have a streamlined body,
where you can at least hope the airflow will follow the body nicely to the end
or as far as it gets.
(the whole point of streamline bodies is doing just that,
keeping the difference between the front pressure area and the back pr.a. as
small as possible)
ps. while we are at it,
one good aspect of the design of the python is that is is so low.
near to the ground you have less wind (like in the weather, wind).
so when the person on the diamondframe is pushing against bad headwind,
apart form the normal recumbant advantage (smaller frontal profile),
you will actually experience less headwind down below.
//dj
> Hi all,
>
> I've been following the discussion for a couple of days. I am thinking
> about
> building a Python, and in my opinion the only real drawback of the design
> is
> the poor stability when coasting at high speed. So I want to find a
> solution.
>
> Regarding the tailfin, Dirk Jan, are you sure it couldn't work? Since the
> pivot point is between the front and the rear wheel, a force trying to
> straighten up the rear wheel would also indirectly try to straighten up
> the
> front wheel, shouldn't it? If so, one could either place the fin far enough
> behind the rider to avoid the turbulence or place it right behind the rear
> wheel, but lifted up above the turbulence from the rider.
>
>
> Oivind
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