OK, I'm willing to concede this arguement, chalking it up to semantics, differences in definitions, and assumptions used by the author. Using my definition of agility (the ability to change direction quickly, a very small aspect of the overall handling characteristic of a car), I do beleive that a car with the CG as far back as possible, thus moving the CG closer to the center of rotation of a fixed reference frame, is ideal. This will disrupt the 50/50 weight distribution, considered to be important in the overall handling characteristics of a car (another illistration, a childs wagon with the front axle/handle turned 90 deg, will it be easier to pull if a heavy box is located at the rear of the wagon, or the center?). But if the author meant more by using the word "agile", by also meaning the ability to sustain high speed through a sustained turn, then a 50/50 distribution is important, and to keep this, a smallest moment of inertia about the CG, or geometric center, is desired. And if a moving reference frame is used (although I still think that it needs to be transformed to a fixed reference frame to be of most use), the car will rotate about it's CG or geometric center.

 

God, I love this board.

Armchair rocket scientists and real rocket scientists have a theorhetical debate. Cool!

I've owned a 911 Turbo (rear engine), Ferrari 308GTS(Mid Engine) and now a S2000 (front-mid). All I can say is that the S2000 feels the most nimble when stock. The 911 felt faster but "twitchy". The Ferrari was a pig, but a sweet sounding pig. Of course the Ferrari was a 1979, the Porsche a 1988 and the S2000 brand new. So the cumulative years of automotive advances may have had a lot to do with it.

 

someone please LOcK this thread!...they reminded me of my physics teacher. YOIK!

 

I think I need an aspirin and a "Physics for Dummies" book.

 

It is possible but unlikely that you will find a front engined car and a rear engined car with the same MOI - even if they both have 50/50 weight distributions.

In any case, 50/50 weight distribution helps in steady state balance of a car in a turn - ie. a skidpad or constant radius turn situation. However, what may affect this is a difference in front/rear tire width difference as well as in suspension tuning. Having a 50/50 to start with makes suspension and tire tuning easier.

Having a low or more centralized MOI makes the care more responsive to changes - whether if driver or environment induced.

 

I thought Polar Moment of Inertia was when a Polar Bear can't stop at the edge of the ice, and slides into the water on accident.

Now I am really confused.

 

I never thought this post would generate so much discussion!

I'll have to leaf through a Physics text book for more topics!!!

 

That was fun. Find another article I can pick apart.

 

Thanks for a little comic relief from what was becoming a tiresome discussion

[QUOTE]Originally posted by Bobway:
[B]I thought Polar Moment of Inertia was when a Polar Bear can't stop at the edge of the ice, and slides into the water on accident.

Now I am really confused.

 

[QUOTE]Originally posted by Bobway:
[B]I thought Polar Moment of Inertia was when a Polar Bear can't stop at the edge of the ice, and slides into the water on accident.

Now I am really confused.