Would the M15 have even better roadholding if....

[CRB1]

The slope of the back clam continued to the very rear of the car (rather than levelling off), thus reducing the depth of boot space particularly at the rear. This would enable a second and perhaps third horizontal plane to be inserted underneath the existing one?

Would this improve roadholding because of more downforce?

[joust]

From my discussions with Lee the fact that it stays level actually improves downforce at the same time as reducing drag as AFAICR it reduces the vortices at the rear.

It follows the F1 "long tail" idea I suppose?

J

[paulcundy]

CRB1 said:

The slope of the back clam continued to the very rear of the car (rather than levelling off), thus reducing the depth of boot space particularly at the rear. This would enable a second and perhaps third horizontal plane to be inserted underneath the existing one?

Would this improve roadholding because of more downforce?

No

[paulcundy]

paulcundy said:

CRB1 said:

The slope of the back clam continued to the very rear of the car (rather than levelling off), thus reducing the depth of boot space particularly at the rear. This would enable a second and perhaps third horizontal plane to be inserted underneath the existing one?

Would this improve roadholding because of more downforce?

No

Dear CRB1,
Apologies for appearing rather terse and perfunctary but its been a busy day.
Regards
Paul C

[DanH]

A rounded rear is bad news in terms of downforce. Look at something like a Mosler with extended and fairly abrupt rear.

[m12_nathan]

DanH said:

A rounded rear is bad news in terms of downforce. Look at something like a Mosler with extended and fairly abrupt rear.

Kamm Tail I think it's called.

[joust]

m12_nathan said:

Kamm Tail I think it's called.

Looks like it..

kamm tail:
It was once thought that a long tapered end in the shape of a vehicle would give it the most aerodynamic configuration. W. Kamm discovered that the length of the end would have to be so long as to make the vehicle unpractical. There would also be an increase in surface area which would also create its own frictiondrag. He found that if he cut the theoretically long tail in half he would have both good aerodynamics and minimal surface drag. This sharply cut off rear end is named after him.

http://en.wikipedia.org/wiki/Kammback

J

[paulcundy]

DanH said:

A rounded rear is bad news in terms of downforce. Look at something like a Mosler with extended and fairly abrupt rear.

Or the Audi TT. These fell of the road due to their rounded ends . They stopped when they put that little gurney across the top of the boot.

It is unbeleivably counter-intuitive that a flat vertical wall facing the airflow can reduce drag.

Regards
PauL C

[mindgam3]

The more curved the shape, the more chance the flow has to seperate.... seperation = more drag, less downforce

[GreenV8S]

mindgam3 said:

The more curved the shape, the more chance the flow has to seperate.... seperation = more drag, less downforce

A curved rear surface in a low pressure zone will produce lift and drag, and since the air flow is bound to separate at some point the amount of drag could be quite high.

[Mannginger]

joust said:

m12_nathan said:

Kamm Tail I think it's called.

Looks like it..

kamm tail:
It was once thought that a long tapered end in the shape of a vehicle would give it the most aerodynamic configuration. W. Kamm discovered that the length of the end would have to be so long as to make the vehicle unpractical. There would also be an increase in surface area which would also create its own frictiondrag. He found that if he cut the theoretically long tail in half he would have both good aerodynamics and minimal surface drag. This sharply cut off rear end is named after him.

http://en.wikipedia.org/wiki/Kammback

J

Aha so that's what this is all about then?

Edited by Mannginger on Monday 3rd July 08:58

[V6GTO]