At first glance the newer all-black Halda Speedpilots all look the same; but they are not the same. The differences are worth knowing if you considering buying a Speedpilot for use in a rally. The Halda Speedpilot was developed in the 1950s to help keep rallyists on time. Two of the last models that were produced were the Speedpilot Model IV and the last, the Speedpilot Model V. These two models of Speedpilots are shown in the photo below.
Halda Speedpilot Model IV, on left, and Model V, on right
In those days almost all rallies were timed to the minute. Teams were required to check into the controls on their target minute. The Speedpilot was set up for a leg by first making sure that the clock was wound sufficiently and set for the right time according to the rallymasters time. The clock is wound by turning the lower right hand knob to the right. The clock time is set by pulling the lower right-hand knob out and turning the hands to the proper time.
Once the clock is correct, the odometer needs to be set at zero at the start of the leg. This was done by turning the lower left hand knob. Next the start time has to be set. This is done by pulling the bottom center knob out which then turns the red hand on the clock face. The red clock hand is then turned to the start time minute. For example, on the Speedpilot Model V shown above, the red clock hand is set at 15 minutes past the hour. This would be the set point if the out time was at 8:15AM, for example.
The last set up activity is to set the required average speed for the leg. This is done by turning the lower center knob which turns the red hand on the left side dial face. Again looking at the Speedpilot Model V in the photo above, the target average speed is set at 30 miles per hour.
Once the leg starts, the goal is to keep the white clock minute hand aligned with red minute hand on the clock dial. If the red minute hand falls behind the white minute hand then the car needs to travel faster and conversely if the red minute hand gets ahead of the red hand, then the car should slow down. Think of it as the car’s average speed is reflected by the speed red minute or pilot hand.
Close Up Of The Speedpilot Model IV
The main difference between the Speedpilot Model IV and the Model V is the operation of the knob on the upper right hand side. On the above picture of the Model IV, no setting is visible next to the upper left hand knob. On the Model IV that means that the Speedpilot is operating in its normal mode. In the photo of the Speedpilot Model IV below, the upper left knob is turned to display a reading that says “1/2 Scale”. That means the effective average speed is half of the value set on the left hand speed dial. In the case shown below the average speed dial is set at 38 miles per hour, so at half scale, the actual average speed setting is 19 miles per hour.
Speedpilot Model IV Set To Half-Scale Speed
The Speedpilot Model V works in a similar fashion except that the upper left knob has a third setting labelled “Off”. This is shown in the photo of the Speedpilot Model V below. This is a very useful setting as it turns the Speedpilot off or in effect sets the required average speed to zero.
Halda Speedpilot Model V
This feature is very useful. Say, for example, you miss a turn then realize a minute or so later that you are off course. Find a clear reference point, turn the Speedpilot to the “Off” position, and then turn the car around. At the reference point, note the mileage in your main odometer, say a Halda Twinmaster and measure the distance from the reference point to the point where you are back on course. Say, for discussion purposes, that the distance from the reference point back to the proper course is 1.32 miles. Once you have regained the course, follow the proper course 1.32 miles, then at that point turn the Speedpilot back on again and continue to follow the course. The Speedpilot Model V will be displaying the correct values and you will know how much time that you need to make up. Without this feature, using the Speedpilot after you go off course becomes more complicated. For this reason alone, the Model V is much more desirable than the Model IV in a car rally.
The is another additional feature that is available in a Halda Speedpilot Model V as compared to a Speedpilot Model IV. That feature is found with the odometer knob on the lower left hand side. On both models rotating the knob will allow navigators to reset the odometer to zero. On a Model V, navigators can pull out this knob to a secondary position. By turning this knob clockwise, distance can be added to the odometer reading. At the same time as the odometer is advanced, the red minute hand on the clock advances according to the setting on the average speed dial.
As a result of the increased functionality of the upper and lower left hand side knobs in the Halda Speedpilot Model V, it is possible for the navigator to maintain the correct odometer reading and timing along the rally course. For example, suppose that the official mileage to a sign was 23.63 miles, then if the odometer value of 23.63 is reached on the Speedpilot Model V before the sign is reached, then the navigator should use the upper left hand knob to turn the Speedpilot off until the sign is reached and turned it back on at that point. If on the other hand, the value of 23.63 is not reached when the car get to the sign. Then the navigator should note the mileage displayed at the sign and compare this to the official mileage. Suppose that the displayed mileage at the sign is 23.58 instead of 23.63. This would mean that the mileage on the Speedpilot is 0.05 too small or short. To correct this on a Speedpilot Model V, the navigator should pull the odometer knob out on the lower left hand side and turn it clockwise to add 0.05 miles to the current odometer reading. This will simultaneously adjust the red timing hand on the right hand dial as well. These features on the Halda Speedpilot Model V will assist greatly with keeping the rally car on time.
There is another difference between these two models that is of interest to rally navigators. Take a careful look at the hands on the Model IV and then look at the hands on the Model V. The ends of the hands on the Model V are much narrower, which will permit a more accurate setting and reading of the hands. In addition, the ends of the hands are bent down close to the face of the dials to reduce parallax errors when reading or setting the hands on the Speedpilot. These are small but important improvements that were made by Halda when they upgraded the Speedpilot from the Model IV to the Model V.
Note that the scales of both of these Halda Speedpilot go from 25 to 90. This is because the face is set up to read in miles per hour. Some Halda Speedpilot models read from 40 to 150. These models are set up to read in kilometers per hour. Be sure that you know what navigation units you will be working in before you buy your Speedpilot.
I hope that this discussion helps when you are considering purchasing a Halda Speedpilot. By the way, I have a Halda Speedpilot Model IV for sale. See the photo of this unit in this post.