[python] Re: Birdcage Python 2561 km
- From: "Matthias P. Nowak" <MatthiasPeter.Nowak@xxxxxxxxxxxxxxxxxx>
- To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
- Date: Wed, 09 Sep 2009 12:25:08 +0200
Jürgen Mages wrote:
> Hello Serge,
>
>> I reached 2561 Km with my Python Birdcage
>
> To avoid misunderstandings: While pedalling, the python is stable at any
> reachable speed. The pulling front wheel counteracts and outweighs the
> negative trail effect. The speed issues are limited to coasting.
This confirms what I think is the reason for stability. The usual upright bike
theory
says that the python is not stable - under the assumption that there are no
forces beside
the linkages between the 4 bodies - the 2 wheels, front and rear section.
One of the old papers I found, mentions that negative trail is unstable unless
one
applies a constant spring to the steering. And one python-rider mentions that he
accelerates when he gets into trouble and that this helps.
Hence, the front pulling the rear part, and the push forces of the legs are
presumingly
the forces that are needed for stability.
A direct conclusion of this line of thought is that one should use the rear
brake when
in stability trouble.
>
>> If the speed of 35 kmh is reached the bike becomes very stable, I
>> think it's a consequence of the rotating forces ...
Gyroscopic effects are thought to be just marginal. Maybe I should crunch the
numbers this fall and do some calculations using Octave.
> I have no problems with that. My P3 looks homebuilt, even for
> non-skilled viewers ;-) Yours is indeed truly beautiful.
Oh yes, I'm admiring this construction.
best regards, Matthias
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