New Cosmonaute...dumb question...

[CarolinaReef]

I love the 24 hour display:-) Already have the Chronomat Evolution and now learning the slide-rule. However...

What are the inside dial numbers 1:10, 1:20, 1:30.....etc for? O|

Thanks

[altro]

I love the 24 hour display:-) Already have the Chronomat Evolution and now learning the slide-rule. However...

What are the inside dial numbers 1:10, 1:20, 1:30.....etc for? O|

Thanks

Hi CarolinaReef,

The scale you mention is used for conversion between hours and minutes - in truth something that most of us do mentally quickly and easily. But this scale is not unique to the latest Cosmonautes; I can't think of any Cosmonautes that don't have it (please correct me if I'm wrong).

It was there on the very first Navitimer in 1952 to use the "Type 52" slide rule and as far as I can recollect there has only been one slide-rule Navitimer that did not have it. (There were a few non-slide rule Navitimers of various designs during the 1950/60's to 80's).

Check out Jean-Michel's site for a few more thoughts and a picture:

http://www.lesmala.net/jean-michel/navitimer/convert.htm

Cheers,

[Kurt Koerfgen]

I love the 24 hour display:-) Already have the Chronomat Evolution and now learning the slide-rule. However...

What are the inside dial numbers 1:10, 1:20, 1:30.....etc for? O|

Thanks



Not a dumb question at all.....


The Navitimer is in essence a combination of navigation sliderule and watch. That is where the term NAVI-TIMER originated from.

Technically speaking; the sliderule part allows you to perform multiplications and division by adding, or subtracting logarithms.

For example:
If you were to figure out how long it would take you to fly 70 miles at a ground speed of 460 knots you would move the 460 over 60 and read slightly over 9 (minutes) under the 70. In this case the moveable bezel would represent distance or speed values and the fixed dial would represent time values.

How about flying 700 miles at 460 knots?
You could either use the same scale and read slightly over 90 minutes, or read the inner scale and get slightly over 1:10 (1 hour 30 minutes) instead.

The inner scale is just a convenience for values that are bigger than the one shown on the outer scale (of the fixed part of the dial).


I hope it could make this clear enough as, with the ariival of more convenient electronic calculators, the basics of sliderules have largely been forgotten.





Best regards,




Kurt
Moderator