How much steering lock is "enough"

[debgeo]

Plus they use tire stagger and rear end to steer thru corners.

[John Burk]

"John are you talking about centrifugal force in cornering?"

jl , how would you do it ?
 

[jl222]

"John are you talking about centrifugal force in cornering?"

jl , how would you do it ?
 

  I don't know how to do it but in Tune To Win there's a chart with slip angles of tires '' the angular displacement
between the plane of rotation of the wheel [the direction in which the rim is pointing] and the path that the rolling tire will follow on the road surface'' Depending on type of tire at .6 coeficient of friction the slip angle varies from
2---6 degrees. Exceeding these values the tire brakes loose. Using the smaller bville tires and running on salt your calks look pretty close and show why Ab Jenkins needed such a big circle for those endurance runs.
  I would still like enough steering to be able to steer into a spin even if it didn't do any good

                        JL222

[John Burk]

The formula for centrifugal force is :
 weight x speed squared / acceleration of gravity x radius

Because the sum is Gs the weight is 1
1 x 294 ft/sec squared / 32 x 4500 ft radius = .6 Gs (salt traction)

[gidge348]

Thank you all for the comments and PM's that is really good input and seems to make sense now.
Please let me know if I have got it wrong....

So if we work on 0.6g being the maximum traction available on salt, at 200 mph the minimum radius would need to be no less than 4500 ft.

A 4500ft circle would have a circumference of 14,136 ft (4500 x 3.1415).
My car has a wheelbase of 210 inches or 17.5ft.

In order to find the angle of the steering we take circumference divided by the wheelbase of the car to give the amount of the circle covered by the car and divide that into 360 to give the angle of the steering.
360 / (14,136/17.5) or 360/807 or 0.44 degrees........ not very much.

So if I get anywhere near 5 degrees it would be pretty much game over anyway and probably better to take a spin rather than get into a tank slapper.

Here’s another problem for the learned people of this site.

Take a worst case scenario, a spin & travelling sideways down the salt 200 mph.

Now if we take the maximum traction available as 0.6g, the cars track width is 32 inches, the height is 30 inches. I do not have a height yet for the centre of gravity but let’s say its 12 inches.

What would be the calculations to work out if it definitely would start to roll disregarding hitting a hole, crack, debris, blown tyre etc.

Lower COG, wider track, less speed or less traction would all make the chances of rolling less but it would good to have a calculation that could change variables to make sure there is a safety margin.    

[SPARKY]

Some keep the throttle nailed if they KNOW they are going around---let up if they think they can get it to stop the rotation--Lakesters usually dont snap like a roadsters.

[jl222]

  I would have enough steering angle to be able to steer into the spin, the 222 Camaro has been saved more than once by this ability

            JL222

[bvillercr]

When ever I get too sideways to continue I always put in the clutch, we have a lock rear end and if you don't clutch it you will go around.  If you don't have enough steering you will never be able to save a spin.  Here is a video of me getting out of shape at El Mirage, you can see how far I move my hands to steer the car.

http://www.youtube.com/watch?v=Udo7XM472Qk

another run, but an easy one trying to get through the lights under power.  Didn't make it and get sideways again.


http://www.youtube.com/watch?v=NJZbf4_IUeo

[jl222]

  Just stopped by to see Arley Langlo's streamliner build and he has about 10 degrees of steering, anymore and
tires would hid frame.

                    JL222

[fastman614]

The steering stops rule was not always in the rule book. I do not remember exactly when it was put in .... I do know that we had to retrofit steering stops on to our Vega, so i am guessing it was early 1990s.... what I recollect is that was NOT to physically linit your car to a certain amount of degrees- no fis ands or buts- it was about not loading your steering box or rack and pinion and destroying it in the even of a spin and your steering getting away on you.  We have our Vega limited to about 15 degrees..... on a 100" WB car, it turns fine in the pits..... the lakester is also about 15 degrees.... on a 220" WB car, it takes a bit of planning to make a turn in the pit area.