gyroscopic effect of high RPMs

[zak]

I spent the sun filled weekend bombing around in my 250 SL and loving it. My home  area is all hills and switchbacks and the car at 35 - 45 MPG and 4000 RPMs just eats them up.
It seems that driving at 4500 rpms the car handles much better then if I drive at a higher gear and lower rpms.
Does the engine act as a gyroscope to steady the handling or is … just my imagination ?
jz

[Chris Long]

Would expect it to be more about the power band and increased engine breaking when coming off power.

[thelews]

35-45 mpg?  That's quite the mileage.

[RobSirg]

Have to assume you mean MPH (not MPG) and also assume that you have a 4 speed.

I concede that driving a 250SL 4 speed through the hills at speed is a lot of fun.

I would agree with Arct1k that the better handling is probably attributed to the better control we have over the car at high revs by using the engine braking.

Here's something else I notice - I believe Pagoda's handle the best when the Hardtop is off and the soft top is folded away. Obviously the hardtop being so heavy I can feel more torque without that extra weight. As for the soft top - I believe having it folded behind us gives the car better F-R weight distribution and better balance.

Either that, or its the feeling of the wind rushing through my non-existent hair 

[stickandrudderman]

There would be more of a gyroscopic effect from the wheels (especially if steel) than the engine and although I'm not a chassis dynamics engineer, I would expect that to have a negative effect on handling rather than positive.

[MikeSimon]

The gyroscopic effect works in the plane of rotation and will make it difficult to move a rotating body out of that plane. That means, if there would be any effect it would - like stick says - have to come from the wheels. It would make it harder to steer, i.e.; move the front wheels out of the plane of rotation.

[mdsalemi]

There would be more of a gyroscopic effect from the wheels (especially if steel) than the engine and although I'm not a chassis dynamics engineer, I would expect that to have a negative effect on handling rather than positive.

I too, am not a chassis dynamics engineer, but do know that true gyroscopes have their mass at the far edge on a rotor, off the center axis (and gimbal mounts, of course). Remove the mass on the rotor, and the effect is somewhat nil. Thus on our wheels, to use Stick's point, the mass is at the axis (hub and bearings); gets a bit lighter as you move away from the axis (wheel) and is lightest at the edges (tire). Doesn't mean there isn't an effect, just that it isn't an optimal one. You need that "flywheel".

All that being said, I've never heard anyone ever bring up "gyroscopic effect" when talking about anything on automotive handling!

[JamesL]

Drive it like you stole it and smile. 

[cfm65@me.com]

Zak,
Me thinks, you are misunderstanding the terms, torque effect and gyroscopic effect.
Try again.
Chris
Cape Town

[zak]

Thanks for the replies and the physics and dynamics lessons....
Yes, I meant MPH, not MPG, sorry.
The engine breaking and downshifting do add the verve.
I am just starting to lose my fear of higher rpms, but my steady engine temp tells me all is well at 4500.
So I will drive as stolen and smile some more.
thanks,

jz 

[stickandrudderman]

I put the question to a friend who is currently employed by one of the top F1 teams as a chassis dynamics engineer and this was his response:
"Yes, you do get a gyroscopic effect on steering weight and self-centering effect. It's quite dependent on the suspension geometry, especially how much castor you have."

[mdsalemi]

"Yes, you do get a gyroscopic effect on steering weight and self-centering effect. It's quite dependent on the suspension geometry, especially how much castor you have."

...and this tells us...what?

[zak]

it tells us that maybe the engine does hunker down the car at high RPMs and high speeds.
Hunker ?

jz