I keep seeing references to how the Curta was great for use in rallying.

I can imagine it was much easier to use than a slide rule with all the motion in the car, but what exactly were they calculating?

Isn't rallying just getting from point A to point B as fast as possible without crashing?

Has rallying changed since those days? The only rallying I see now is where the co-driver is shouting out pace notes. He'd have no time for calculating anything anyway.

https://stevemckelvie.wordpress.com/2011/02/18/rallying-with-a-curta-calculator-part-1/

and

http://www.rallyracingnews.com/manuals/curtaman.html

Thank you for the links.

While they go into detail about how they use the curta, I am still no wiser in what they are actually trying to calculate and why.

Is this a different sort of rallying than Colin McRea did?

My understanding is Road Rallying is about percise timing, hit mileage at exact times. Most odometers are off a bit, so one thing they need to correct on the fly is the actual distance traveled vs what there odometer says. This way they can be at the right place right on time and take no penelties.

at least thats my understanding.

u/davhamm is right I believe; they used the Curta as an abacus, an adder-upper, a totalizer, against a stopwatch, to make sure they were hitting their targets.

You calculate a running average of speed or total distance travelled - sometimes you run a regularity rally in which it is important to travel at e.g. 50 mph exactly. The advantage of a mechanical calculator is that you cannot accidentally reset it, which is a problem with electronic ones. For the same reason a mechanical calculator is great for tallying the totals in e.g. a game of cards or scrabble.

stenella wrote:

You calculate a running average of speed or total distance travelled - sometimes you run a regularity rally in which it is important to travel at e.g. 50 mph exactly. The advantage of a mechanical calculator is that you cannot accidentally reset it, which is a problem with electronic ones. For the same reason a mechanical calculator is great for tallying the totals in e.g. a game of cards or scrabble.

And of course it will never switch itself off.

So they still have their uses today