zero polar moment of inertia

[darksag3x]

how would an F1 car behave/perform on a track with zero polar moment of inertia?

[Cyco]

The car would be be so hard to control due to its propensity to spin it would not be useful.

[RH1300S]

Surely that's impossible to achieve, so a bit of a daft question..........

[ss.vamsikrishna]

darksag3x ur topic is bit confusing , u were talking about the car's polar moment of inertia........right.............please do correct me if i am wrong..
it will be more interesting to watch a F1 car with high polar moment of inertia as it will be very stable and totally in control, so speeds will definetly increase.....

[Guest]

High Polar Moment of Interia will not make the car go faster. I might make it more predicatable. F1 designers go to great lengths to lower MOI. With a lower MOI the car turns in easier and is more responsive to corrections (of course it might be over-responsive to some).

I am pretty sure that a lower MOI is kinder to the tyres too as it takes less energy to initiate the turn.

[ss.vamsikrishna]

then i would say , F1 car designers have to strike a balance between high
moment of inertia and low moment of inertia as if it is very low MOI it will spin the car , and very much soon out of control at turns.and it may depend on track to track , more of straight line track - high moment of inertia and more of curves - low moment of inertia......


u can check the following site

http://www.k12.nf.ca/gc/Staff/Teachers/ ... moment.htm

"high polar moment of inertia Designs such as these are very stable in straight line travel, making them "safe" handling designs "

[RH1300S]

High Polar Moment of Interia will not make the car go faster. I might make it more predicatable. F1 designers go to great lengths to lower MOI. With a lower MOI the car turns in easier and is more responsive to corrections (of course it might be over-responsive to some).

I am pretty sure that a lower MOI is kinder to the tyres too as it takes less energy to initiate the turn.

BTW - that was me, didn't realise I wasn't logged in.

[RH1300S]

No, a low MOI won't spin the car. Losing grip in a low MOI car will make a spin more likely. Until the car loses grip it is bound to turn (respond to the wheel) faster with a lower MOI. Typically F1 cars don't assume a four wheel drift in corners, so logically the lower the MOI the better. It's up to the (very well paid and top class) drivers to not overstep the limit and when they do to have the necessary car control to bring it back. Don't forget a lower MOI car will respond to corrections faster too.

I'm sure that there is such a thing is too low MOI, but we aren't there yet.

Back in the days of drifting cars, some manufacturers aimed for higher MOI's to make the car drivable beyond the limit. But cars like the Lotus 49 showed that in the right hands a lower MOI car would be the quickest way around (Ok, it had other advantages too)

[Ayrton]

increasing MOI increases STABILITY decreases RESPONSE
decreasing MOI decreases STABILITY increases RESPONSE

it's up to the engineer and driver to find an optimal compromise

[West]

Engineers would probably want the lowest polar moment of inertia possible... why do you think they've been shifting weight forwards over the years

If you want to increase stability while reducing polar moment of inertia, the team should be increasing mechanical/aero grip, alter differential and traction control settings, etc

[Ayrton]

Engineers would probably want the lowest polar moment of inertia possible... why do you think they've been shifting weight forwards over the years

If you want to increase stability while reducing polar moment of inertia, the team should be increasing mechanical/aero grip, alter differential and traction control settings, etc

You are right in what you say, but let's say for instance the driver complains that the car is too "nervous", meaning reacts too quickly for the driver, then weight can be shifted, be it ballasts or moving components of the car, such that the MOI is increased the car will rotate, roll or yaw in a slower manner and thus more predictable way and more STABLE...giving the driver more time to control the desired path. But obviously both the driver and engineer want the maximum amount of response given this condition. Same goes for the response inherent in tires.

[Jersey Tom]

You'd always want to bring the MOI down as low as possible. There's no way in hell you're going to get it "tiny", theres a physical and practical limit, but you might as well see how close to that limit as you can get. Lower MOI, less it takes to yaw the car around.

[Ciro Pabón]

I do not know if you have seen the thread I started on spherical wheels: with them the rotational inertia is of no importance. You can keep the car pointed in any direction you want while you take the curve.

Besides this concept, the only thing I know with zero MOI is a geometrical point. I have not seen cars with such a low MOI that they become "nervous". If you have one, I want it. Probably, it is a bike.

To answer the question: you could rotate the car in any direction without any effort.

[ginsu]

I don't think you play with the MOI very much when designing the F1 car. I would think that the engineers would design the car with as little MOI as possible and use the dampers and rollbars to fine tune the handling. The only way that an increase in MOI would be favourable is for a car that is not going to turn, i.e. a drag racer.

yes, a sphere is ideal from a rotation standpoint, but i don't see how you could make a spherical car. although, it would change direction quite well if you could.

[Ciro Pabón]

i don't see how you could make a spherical car. although, it would change direction quite well if you could.

It is not an spherical car, only the wheels. You can keep the car pointed in any direction while the wheels push it sideways. You do not have to rotate the car.

BTW, I have seen, maybe a year ago, a radical car (Peugeot?) that has a giant wheel that goes round the cockpit. It is beautiful, but I have not been able to find it on the web again.

I forgot to mention that a car with zero moment of inertia would have zero resistance to bending. It would be the worst chassis in the world. When you design a bridge (or a chassis, I imagine) the torsional and bending moment resistance depends on the third moment of inertia, wich is the integral of the area, when you "turn" it around an axis perpendicular to the load. No inertia, no resistance.