Time To Turn

Most instructions in rallying provide you with the distance that you should travel to arrive at the next turn, plus the speed at which you should travel. In "time to turn" instructions, the Rally Master gives you the speed at which you should travel and the time at which you should turn.

If you will recall from an earlier column on timing,

time = distance / speed

...and if you remember your algebra, this equation also reads:

distance = speed x time

Now, to make this work, the speed needs to be expressed in the same units as the time. If you are looking at time in minutes, the speed must be in kilometers per minute. If you are in seconds, the speed is kilometers per second. In other words, 66KPH = 1.1 KPM = .0183 KPS.

I find that sections with these instructions need to be worked out in advance of arriving at the start of the section. Otherwise the turns seem to come entirely too quickly! The instructions can be worked out manually as described or, if you use a programmable calculator, they can be worked out by running them quickly through the program and writing out the distance for each turn. I like to get this done at the odometer check if possible. Otherwise, I abandon my driver to do his own timing! Be alert to the fact that not all speed changes will come at corners. If your next turn takes you beyond the speed change, you will need to calculate the time used to get to the speed change and then the distance that you will travel at the new speed to arrive at the specified time.

It all sounds simple doesn't it? Work through this sample and see if you arrive at the same distance as is shown below. Times are non-accumulative and shown as minutes and hundreths of minutes. Distance is shown from start of section.

CAS 70.4 1.01  TSSA 1.19 Km
  .80  L 2.12 Km
CAS 54 1.78  SA 4.21 Km
  2.29  L 6.27 Km
  .04  L 6.31 Km
  1.38  SA 7.55 Km

I hope that it all seems simple now. You never know when one of these sections is coming your way!

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Last Updated: 2002-01-17
Copyright © 2001 Gail L. Walker, reproduction forbidden without written authorization.