[python] Re: Python stability
- From: Jürgen Mages <jmages@xxxxxx>
- To: <python@xxxxxxxxxxxxx>
- Date: Wed, 16 Feb 2005 13:33:22 +0100
Hello Ray,
welcome to our list. I think you are member #50.
Great to have some more mathematical brain power
here. Dirk already made some nice calculation works.
The most important is smallish negative trail, no more than
-4cm. A longer wheelbase, with rear mass CG more forward,
a more horizontal pivot angle and several others can add stability.
I have heard that NT bikes could be stable, if the trail
is not too big and if there is enough weight on the
front wheel. Maybe that corresponds to your idea.
So far we have the practical affirmation that a python
with the usual dimensions is fairly rideable with
45 km/h on flat terrain and 50 km/h (14 m/s) coasting
downhills.
The latter requires more skill because the front wheel
is not pulled but pushed.
At low speed (< 10 km/h), the python is more stable than the
flevo.
I noted that the "height" of the pivot is not the real factor,
it is the angle and trail it creates.
Right.
It appears that if the pivot was directly in front of one's
crotch (!) it would add self-stability, but as it got higher
up it would seem to make leg-steering awkward.
According to most people, the steering axis has to go
through the middle between the two hip joints to minimize
the pedalling/steering interferences.
I wonder how the Tom Traylor like bikes are rideable.
I'm still working on the script and understanding the meanings
of the stability matrix equations, hopefully I'll be able to
contribute something more concrete soon.
We are looking forward to your work.
In the next time I will build a scrap python which will
undergo a lot of geometry and steering experiments.
Some of them are: rubber pivot, four bar linkage pivot,
shallow steering angles around 50 degrees and lesser
negative trail. Will let you know.
Cheers,
Jürgen.
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