[Petrus]

Works a treat btw.

 

[Petrus]

Removing weight at the far end of the car is more significant than at the center of the car, just as you explained. Although this weight saving is something I'll prob never do unless it becomes a track car, it's an interesting topic.

Ever watched ice skating? The pirouette? The skater increases rotational speed by centering his/her mass. The exact same mass, just moved inwards; the same angular moment, more speed.
Now translate that to the car changing direction; ´rotating´, with/without weight at the far end(s). Remove weight and it will change direction quicker.

Whether ´you´ will notice that on the road depends.
A perspective being that some owners actually ádd some weight to the frump (like moving the tool bag there and adding extra stuff) to make the car feel less skittish on the highway. Same thing and appearantly noticed
One owner on the UK forum actually tríed test my proza by adding/deleting weight to/from the front bucket and was baffled about how obvious the difference was

 

[SDSUsnowboards]

If I had no understanding of your limited options, due to the nanny-state you live in, I'd say the bag is going too far. Instead, I'll say you didn't go far enough. I'd put it against the firewall.

There really can't be any doubt that weight distribution matters. One experiment I like to tell people to try is to go to a place with shopping carts. Then place one heavy object, such as a 40 lb kitty litter, in the cart at the front. Try to move the cart forward and do a slalom. Then place that weight in the back of the cart and try again. It sufficiently illustrates the difference. Examples like ice skating are a bit abstract. Who has ever done a pirouette ice skating?

An on that note, it seems to me all of the follow hang beyond the axles:
radiator, washer fluid, coolant reservoir, 75% of the exhaust, and power steering pump. It seems to me all of these can be moved, and some lightened.

 

[Petrus]

If I had no understanding of your limited options, due to the nanny-state you live in, I'd say the bag is going too far. Instead, I'll say you didn't go far enough. I'd put it against the firewall.

I have meanwhile shifted it a bit further back but have still used the original wiring and tubing. Good enough now

Lightened the exhaust móre than 75%, deleted the p.a.s. and... then some; about 40 kgs in total deleted from beyond the axles. Imagine that with the shopping cart

 

[Petrus]

Examples like ice skating are a bit abstract. Who has ever done a pirouette ice skating?

Sit yourself on a swiveling desk chair.
Stretch arms & legs out wide.
Have someone push/pull you to spin.
Now pull legs & arms in.
Your rotacional speel will increase.

By all means try it with dumb bells in your hands. For max effect simply drop those when pulling your extremities inwards.

 

[SDSUsnowboards]

I have meanwhile shifted it a bit further back but have still used the original wiring and tubing. Good enough now

Lightened the exhaust móre than 75%, deleted the p.a.s. and... then some; about 40 kgs in total deleted from beyond the axles. Imagine that with the shopping cart

Better, but still a compromise. Plastic tubing and wiring is cheap and easy to mess with. Or better yet, remove the washer equipment. Any situation justifying the use of washer fluid could be resolved with a pre-drive wipe from a squeegee.

The chair example is improved, because someone can try it at home, but then raises the question, do I want my car to spin faster? No, I don't! It's still a little abstract insofar as imagining how that same mechanism allows for quicker changes in direction (which is really the benefit you are chasing by removing polar inertia).

 

[Petrus]

Better, but still a compromise. Plastic tubing and wiring is cheap and easy to mess with. Or better yet, remove the washer equipment. Any situation justifying the use of washer fluid could be resolved with a pre-drive wipe from a squeegee.

Unfortunately a non working washer is a fail for anual inspection.

The chair example is improved, because someone can try it at home, but then raises the question, do I want my car to spin faster? No, I don't! It's still a little abstract insofar as imagining how that same mechanism allows for quicker changes in direction (which is really the benefit you are chasing by removing polar inertia).

Ah well, If someone still does not understand it I say ´tant pis´.
It seems rather obvious to me as it is the essence of the whole concept of the car; it is even expressed as MR2

 

[rmeller]

...Now pull legs & arms in.
Your rotacional speel will increase...

Well, true, but rotational speed is not the object. Lateral acceleration is the object. You need angular acceleration to get into the corner and get out of it again, but it won't help you go faster, as long as you plan your corners correctly. A car with quick angular response is fun to drive on the road, however, because it lets you do more spontaneous maneuvers. That also applies to emergency maneuvers. So, maybe you can say that it does let you drive faster, because you can press your luck further and still get away with it.

Keep in mind that the wheelbase is just as important as the rotational inertia. This car has an enormous wheelbase, and that is often overlooked. The maximum angular acceleration that the car can achieve is roughly proportional to the ratio of the wheelbase to the rotational inertia.

 

[Petrus]

Well, true, but rotational speed is not the object. Lateral acceleration is the object. You need angular acceleration to get into the corner and get out of it again, but it won't help you go faster, as long as you plan your corners correctly. A car with quick angular response is fun to drive on the road, however, because it lets you do more spontaneous maneuvers. That also applies to emergency maneuvers. So, maybe you can say that it does let you drive faster, because you can press your luck further and still get away with it.

Keep in mind that the wheelbase is just as important as the rotational inertia. This car has an enormous wheelbase, and that is often overlooked. The maximum angular acceleration that the car can achieve is roughly proportional to the ratio of the wheelbase to the rotational inertia.

Example and semantics apart, a lower pmi means less effort needed for a directional deflection. This translates in a potentially quicker movement as well as less lateral friction needed.

A corner is a continuous change of direction. Less pmi means the tyres need to excert less deflecting force at the same speed, meaning more grip left.
This can be kept as reserve for the unexpected or .... for higher corner speed.

I am aware of the wheelbase related properties but since it is a given a moot point no?!

As a side-effect of checking the OBD2 port connections deleted the plastic panel; 403 gramms.