OT: Jeppesen E6B Wind-Easy Computer (Slide Rule)


Jeppesen E6B Wind Easy Computer

I need to spend more time with it. I have never owned a specialized slide rule like this. Super cool.


The title now has the correct model name - thank you Geoff for showing me the error of my ways.

Edited: 12 Oct 2013, 10:57 a.m. after one or more responses were posted



If you were a student pilot (in my case, in the 70s) you had one of these (or similar). I used it mostly for wind triangles (which you could also solve with your HP35 and some knowledge of trig). You had to figure out what your magnetic heading should be, based on your desired direction of travel, the speed of your plane, and the speed & direction of the (predicted!) winds aloft. Potentially, lots of error in that last one.

I'm not sure what they learn with these days - probably the pilot app on your android/iphone!


Hi Eddie, that's an E6B, not '8'.

Still used today on smaller aircraft, and still required for all pilot exams. You must have backup to GPS on smaller aircraft (civilian ) in case the batteries die on your handheld and be able to demonstrate its use.

Standard flight computer with the ability to do point to point nav on the wind side as well as wind vector analysis. I use the jepessen CR3 at work. Still use the cr3 although that was in the analog 737 alot, and not so much in the 777.

Fun items, my Breitling from 1965 and LED version from 74 both have the sliderule portions:


Edited: 10 Oct 2013, 11:18 p.m.


A little trivia: did you know that wristwatches were just ladies' accessories before a Brazilian inventor and aviator, one Alberto Santos-Dumont, started using one aboard his experimental flying devices? :-)


Hello Gerson,

While Santos-Dumont was responsible for one of the most famous and timeless designs, the Tank watch produced by Cartier (a friend of the family) there is a controversy as to who did create the first wristwatch for men. That title may go to Zenith or Omega. Even though wikpedia mentions him as the creator of the wristwatch, it was probably Zenith or Omega because of the timeline. The controversy probably revolves around production series or first production.

During the second Boer war (1898) a Canadian officer in the infantry in charge of a platoon asked Omega to create three wristlets as holding a pocket watch and aiming a rifle were not conducive to good targeting. Omega created three wristlets which were not converted ladies pocket watch movements but in fact redesigned to accommodate a winder at 3 o’clock; the lugs at 12 and 6 and a sub seconds at the six

Zenith was asked by a German naval officer at the turn of the century (previous) for the same wristlet design.

Once the watch was worn by the tough men of the military it was no longer deemed effeminate.

I have been (another hobby) restoring wristwatches for 25 years and have this beauty by Omega. The serial number puts it as one of the first dedicated wristlets made for men circa 1900

The last two were created for the first World War officers and are actually called Officers Trench Watches. One is 1918 and the other 1916:

Cheers, Geoff

Edited: 11 Oct 2013, 2:17 a.m.


Wedding gift from my wife, 1991. Still runs!



Yes, actually the Wikipedia article states that "Santos-Dumont played an important role in popularizing its use by men", not that he was the first man to ever wear a writswatch. I think I'd heard about wristwatch first being used during a war, but I had forgotten. Thanks for reminding me!




The red LED Navitimer is very nice. Can you confirm whether the display state is usually blank and only illuminated for a short period by pressing a button on the side?



Yes, only nine hundred made. Also chronograph up to 99h59m .



Thanks - I am going to correct my first post. Amazing the slide rules are still used today.

The watches are super cool.


...that's an E6B, not '8'.

Or originally, E-6B. The US military assigned an official Joint Army-Navy designation more than 50 years ago of CPU-26A/P. That's a slightly irregular JAN nomenclature for this Computer, Air Navigation.

It should actually have been CP-26A/P, for

Unit indicator: CP - A mechanical and/or electronic mathematical calculating device

Model: 26

Modification: A

Installation indicator: P - used only when the equipment is specifically designed to operate while being carried by a person.

Of course, no one in the US military ever actually refers to the device as a CPU-26A/P, even a half century after that designation. But the designation does point out that it is officially considered a portable calculating device...just like most other things we talk about here. So it's not very OT. :-)

My CPU-26A/P is extremely well made. It is surprising how cheaply they go on ebay. There always seems to be about 15 of them on auction for give-away bids, considering the quality of the device, and the doubtless high original cost to the military.


That quartz Navitimer is indeed a very interesting piece of kit. It's hard to believe that Breitling once thought digital watches were a good idea.... I remember my father getting a demonstration of an analog watch with all bells and whistles sometime in the 70s but then going for a digital watch because it was cheaper and more accurate.

I do like to have a circular computer on my watches, too, but find I hardly use it since area navigation / FMS has become mandatory. I was very close to getting a Breitling Cosmonaut once but settled for a Swatch 24hr dial watch and a citizen solar powered model for budgetary reasons ;) (but the Swatch broke after a few years and the Citizen required a lot of repair, too, so the Breitling might have been the better option in the long term).

Thanks to the OP for bringing back memories of flight training days.


Love those Breitlings! A buddy of mine had the Breitling Aerospace, which had both LCD displays and analogue hands driven by stepper motors, so that they could whiz around to the correct time when you changed the time zones. No whiz-wheel, though - in the end, I settled for the Citizen Eco-Drive equivalent, which is great for daily wear and does have a slide rule bezel:

That's the "Blue Angels" model, btw. Like the Breitling Aerospace, it uses stepper motors, but should never need a battery change (the commonest cause of failure of electronic watches, imho) since it has a small solar cell in the face. To conserve power, the second hand stops after dark - when you bring it into the light, it whizzes around to the correct position, something that still amuses me when I see it. And of course, pressing both the big buttons swaps the time on the LCD display for the "analogue" time, causing the hour hand to swing around, forwards or even backwards, to the correct time (the minutes hand moves, too, for those weird half-hour time zones).

You also made me drag out the nav computers I used back in the day, so I set them up on my desk (right-to-left, chronologically - I wasn't planning ahead!). At extreme right, a Pooley's (UK) CRP-1, which has a wind side very like the E-6B. I graduated from there to a Jeppesen CR-5, which fit conveniently in a shirt pocket - but the wind side on the CR devices is much less intuitive and tricky to use. Ironically, the Pooley's device looks as good as new, while the CR-5 is very yellowed with age.

Finally, of course, the 41CX with Aviation Pac, which I used for a while for planning, especially with the ability to print on the 82143A. I also have an original Sporty's E6B calculator around here, somewhere. They both soon gave way to computerized flight planning programs, including one I wrote myself, but the CR-5 stayed in my shirt pocket for many years and I still used it occasionally when flying.


--- Les


Edited: 12 Oct 2013, 11:19 p.m.


Hi Les!

I wear this since five years:



Oh, nice! I eyed that model up, but I'm too far from WWV for it to work usefully. :(


--- Les



Hi Eddie,

This is my self made replica of a B-24 Liberator's E-6B. The airplane crashed in Hungary in 1944.


Now that is neat!


Wow! That is a beauty, George.

If I may ask, was the slide rule made from spare parts?


Thanks. :)

Yes. The paper phototypes from the original slide rule are cemented to a 5 mm and some 1.5 mm thickness plywoods. These parts are covered with transparent plastic film. The white moving scale and the matt transparent round window in the back side are from a russian aerial slide rule. The moving ring in the corner is from duralumin.

Edited: 12 Oct 2013, 5:00 p.m.

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