Tandem front axle

[Dave K]

I was looking at the Covini Engineering C6W:

http://www.coviniengineering.com/english/c6w_1.htm

and had some questions/thoughts, regarding the engineering theory behind the use of tandem front axles...

1) Do you reduce the front spring rates by 1/2, since you have twice as many?

2) Ackermann must be interesting to figure out, with 2 turning sets of tires.

3) Does oversteer increase, with twice as much front contact patch?

Any thoughts on this?

-Dave

http://www.moslerauto.com

 

[PTwizz]

Hi Gunman,

1) You would indeed reduce spring rates by something close to half. The pair of springs on each side of the twin axles act in paralell, so their rates are added together to produce the desired rate to support the corner weight. The text mentions the use of hydro-pneumatic front suspension, and its use in contolling weight distribution between the front wheels. This suggests some coupling between the axles, possibly involving a shared (gas) spring.

2) Ackermann (and steering rate) is calculated for each axle with respect to it's distance from the rear axle(s) centre.

3) The increase in contact patch will tend to increase oversteer, all other things being equal. All other things will not, however, be equal.

Looking at the pictures, I would suggest that the total front contact patch is probably not much different to that of a more conventional sports car with larger diameter, wider front tyres.

Interesting project, nevertheless.

Pete.

 

[yoyo133]

I believe it was Tyrell in the very early 70's that built a formula-1 race car with four wheels up front. Their objective was the use of much smaller diameter tire to reduce the frontal area and improve aerodynamics. It also, as noted, gave it better front end grip. They raced it a few times and I seem to recall that they may have won a race where upon it was banned. This is all from memory so I won't swear by it. The Covini in the real world?? If you build it someone will buy it just because it is different.

 

[MarkEE]

I don't beleive the Tyrell P34 was banned. I think it was the fact that Goodyear had to make the special fronts just for this car which became impracticle.

MarkEE

 

[patprimmer]

I heard it was banned, but that is only anecdotal. I have no evidence to support it

Regards
pat

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