[python] Re: python stability, again...
- From: Patrick van Gompel <patrick_van_gompel@xxxxxxxxxxx>
- To: "python@xxxxxxxxxxxxx" <python@xxxxxxxxxxxxx>
- Date: Tue, 16 Apr 2013 14:23:49 +0200
Hello Peter,
I don't know that program and I don't have answers to all your questions about
it, but a stable bike is not only about centre of gravity (CoG). Just a simple
example: you have a bike which seems to be stable with a 100kg load right in
the middle. Now, take 50kg and put that 1 meter to the rear and put that other
50kg 1 meter to the front. Your CoG hasn't changed, but your (steering)
stability has. For example, I think it's almost impossible to drive a Python
with a 50kg load on the front near the pedals. Your front end will probably
flip left or right and your legs won't be strong enough to keep it centre.
Keep in mind that CoG is an idea to simplify things. Although it can be used to
calculate things like the load on both wheels, for stability you need quite a
bit more.
A good question might be why your other bike isn't stable. Is it because of the
steering, position of mass or a weak construction?
Hope that helps a bit, but I am sure others know much more about it.
Patrick
> From: peter.svancarek@xxxxxxxx
> To: python@xxxxxxxxxxxxx
> Subject: [python] python stability, again...
> Date: Tue, 16 Apr 2013 13:52:44 +0200
>
> Hi,
> I was looking for bicycle stability calculator becase I ran into problems
> with stability of my little rowing bike project model. It is model(to this
> time without drive) where I could change to some degree parametres of
> steering. But that beast is is not very stable, even if it is possible to
> ride it. So before I will built final recumbent I must obtain reasonably
> stable model :)
>
> I found this little program on this mailing list (
> http://rjs.org/Python/FrameGeometry.zip ). I even changed a few values to
> obtain selfstable bike at 6.4 km/h, but while I understand some of
> variables, others I don’t understand.
>
> Front mass to pivot, front mass to height... Why not give there only data
> about centre of gravity? While on projected bike will be mass moved(both
> legs and torso of rider) during driving, the centre of gravity would be more
> or less in the same position. And centre of mass is what is loading the
> wheels, isn't it so?
>
> what is "tortional K to pivot axis" ? What is inertial factor and "inertial
> angle of front mass from horizontal"? "inertial angle of front mass from
> horizontal? Front mass and main mass???
> Cheers Peter
>
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