Hi Dave:
I agree the length of the arm affects torque but me thinks it affects
distance traveled also. The two are interrelated. I was only using the top
Fuel tire to illustrate a point about squat or footprint. I also should have
said effective ratio and not gear ratio which is mechanically fixed.
The amount of belt squirming out in front and back (creating the contact
patch) is not adding to forward motion. For example you could have 12 inches
of foot print or 2 inches of footprint. They both eat up HP and
circumference but the shorter one gives more efficient forward travel. But
since we are talking about LSR tires with little or no squat I agree the
effect is negligible as well. Since I am moving I should not have started
this thread. Let's continue this at salt talks. :-) -Elon
-----Original Message-----
From: Dave Dahlgren [mailto:ddahlgren@snet.net]
Sent: Friday, April 25, 2008 10:18 PM
To: Elon; land-speed submit
Subject: Re: [Land-speed] A Protocol Question...
The lever arm affects torque but not gear ratio the whole 'belt has to touch
the ground before you can have another rev. If you think not tell me why.
Get an old or new lol fan belt and play with different shapes, round oval
etc. and see what I mean. With a TF car the OD of the belt changes I doubt
if that happens to a large degree with a LSR tire run at an appropriate
pressure like 75 to 90 psi,
Dave
----- Original Message -----
From: "Elon" <saltfever@comcast.net>
To: "land-speed submit" <land-speed@autox.team.net>
Sent: Friday, April 25, 2008 10:20 PM
Subject: [Land-speed] A Protocol Question...
> Hi Jon. Think of the lower tire radius as a lever arm. It's the lever arm
> (and its length) that does all the work to move the car forward. That
> length
> of the arm also affects the overall gear ratio. And you know gear ratio is
> directly coupled to revs per mile. Think of a top fuel car and the wheel
> growth at speed. As the tires grows in height the lever arm increases in
> length. You might say tire growth is an infinitely variable ratio. Maybe
> this is a poor example, but how about a track-laying Caterpillar tractor?
> The ratios and revs per distance is controlled by the diameter (or radius)
> of the sprocket and not the length of the track. Your tires footprint
> (squat) is a semi-type of track layer, no? -Elon
>
>
>
> while the radius on the bottom half is smaller than that of the top, when
> loaded
>
> -- I don't understand how that would change the circumference. That
>
> is, the distance all the way around the tire does not change -- all of
>
> the rubber must still roll down the road, even if the axle gets closer
>
> to the ground.
>
> Jon Wennerberg
>
> Tall guy with moustache
>
> and a pair of 2 Club hats
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