Braking retardation..MathsGraph Help needed

[Toltec]

Cockey said:

So all this assumes both cars brake at the same rate.

How far back would you have to be to avoid going up the back of a fully braking GT3, if you were driving an average car?

At sixty providing you start breaking about a second before you reach the point at which the gt3 started braking then you can brake half as hard and still miss it. To put it another way if you have a two second gap and start braking within one second even a Ford Anglia would just stop in time.

At eighty this becomes 1.4 seconds, however if you can brake a little harder at around 3/4 of a fairly average car then you are back to just needing a second leeway.

For the pub discussion-

At a second behind you will need to be fully on the brakes of your gt86 within 3/4 of a second or you will be parked in the back of the gt3. If your car is not quite as good as a GT86 then at a second gap you will need to be very quick on the brakes.

At three seconds behind you can stop comfortably using less than half braking.

Edited by Toltec on Friday 29th November 21:14

[cptsideways]

What car does your son drive? What tyres?? ABS? EBD? Brake Assist? Check out tyre reviews...


I'd suggest a little empty dual carriageway practice, son offset at his desired gap in the other lane versus yourself. He has to react to you. I guarantee he will be stopping past you especially if your car has brake assist & you know how to set it off

Mind you I'd check he can at least cadence brake if he has no ABS & has the ability to stop in straight line first, starting from lower speeds.

[PhillipM]

I'd just suggest a slap. Repeat as necessary.

[jmcc500]

two seconds minimum, OR zero seconds, literally touching bumpers. That way the relative speed at which contact is made is zero.

HTH

[Kozy]

silverfoxcc said:

Kozy, a great graph, a vitual bottle of malt, should you partake, for your effort.

Indeed I do! I agree, a good discussion has been had.

I've updated my online chart now so it makes a bit more sense. Get your nipper to have a look at that and try different reaction times, acceleration rates and gap times. In particular, change the default two second gap to one second, and then see how small a margin of error there is for reaction time and/or acceleration before a collision happens. Hopefully it'll be illuminating to him!



Stopping Distance Charts

I had one of the reaction time controls locked at 0.7s which was giving dodgy results earlier.

Edited by Kozy on Saturday 30th November 07:51