Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: gidge348 on September 16, 2010, 03:47:12 AM
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I have been reading though these illustrious pages for a while and have seen a lot of different takes on this question.
“How many degrees of wheel movement is enough”
I have seen a lot of mentions of 3 degrees each way, 5 degrees each way etc, these seem quite small? Previous racing was on speedway where 90 degrees is not enough sometimes :-P
I would be interested in opinions for a 210 inch wheel base streamliner.
Obviously the more the better, particularly when things get ugly, but more lock needs more room and things a pretty tight at the moment.
Any suggestions?
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the rule is 15 degrees left and 15 degrees right maximum---you will need all of that to get around the pits --next month at el mirage i will measure how many degrees it actually takes to make a run and to get off of the track and post it on this thread willie buchta
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It's a car, willie.
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my bike is a sidecar same principles apply as a car except the 15 degree rule willie buchta
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Turn steering until it hits the stops, then apply full throttle. This will work for both bikes and cars. You will be surprised and pleased how little space it takes to make a turn, especially if you are on a slick surface. Nearby spectators will also be impressed.
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Gidge,
My lakester turns 7 deg. in and 7 deg. out. It has 188" wheel base and 1.5" ground clearance and I tow it around on the salt with a dolly that has wagon type steering. This setup raises the front wheels up about 7 inch's, turns tight and helps to get it on the trailer with out dragging.
harvey
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Gidge,
My lakester turns 7 deg. in and 7 deg. out. It has 188" wheel base and 1.5" ground clearance and I tow it around on the salt with a dolly that has wagon type steering. This setup raises the front wheels up about 7 inch's, turns tight and helps to get it on the trailer with out dragging.
harvey
Hi Harvey,
Thanks for that, have you ever come close to full lock when you are on a run?
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My experience has been "WHEN" :-o I needed that much it didnt respond to the earlier little ones :-D Yes I have a "SPIN PIN"
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Thanks for that Harvey, I thought that may be the case.
I just wanted to make sure that I didn't run out of steering before I ran out of .....options, track and ability :-D :-D :-D
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the rule is 15 degrees left and 15 degrees right maximum---you will need all of that to get around the pits --next month at el mirage i will measure how many degrees it actually takes to make a run and to get off of the track and post it on this thread willie buchta
OK, I admit I am slow at times. I cannot find any mention of this in the '10 rulebook, so, either I am missing a whole section or it is no longer specified?
I am laying out the steering and have worked up ackerman to give 14.7° on outside wheel and 15.9° on the inside.
Thoughts, comments?
Thanks, John
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Willie's response was referring to motorcycles. You can set up your steering to your preference. You will need to clear the course and want to move the car in the pits and shop.
DW
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At 200 mph , using the formula for centrifugal force , the most the front wheels can turn without sliding is about 1/10 deg . 6 deg or whatever is for in the pits .
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At 200 mph , using the formula for centrifugal force , the most the front wheels can turn without sliding is about 1/10 deg . 6 deg or whatever is for in the pits .
How do race cars go around corners or make rapid lane changes if that was the case, and how much slip angle of tire-vertical load-coefficient of friction of tire are in formula?
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Jl , at Bonneville the radius of a 200 mph .6 G turn is about 4500 ft . Daytona turn radius is about 1200 ft . The difference is banked turns and more traction .
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Jl , at Bonneville the radius of a 200 mph .6 G turn is about 4500 ft . Daytona turn radius is about 1200 ft . The difference is banked turns and more traction .
John are you talking about centrifugal force in cornering?
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Plus they use tire stagger and rear end to steer thru corners.
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"John are you talking about centrifugal force in cornering?"
jl , how would you do it ?
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"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 :cheers:
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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)
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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.
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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.
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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 :-P
JL222
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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
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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
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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.