This is pure mechanical genius! Too bad they sell for over $1000 today.

Anybody here ever use one?

Curta calculator

I think rally navigators used to use them.

Found this: https://curta.org/
There's a flash emulator there that seems interesting.

JP

There's a model somewhere for 3D printing a replica, but it has to be about three times the size of the original (so maybe coffee can sized) because of the lower precision of the parts.

They are neat for sure.

A family member used to have a Type II Curta - more digits.

Some people nicknamed them "pepper grinders" due to the sound they made when you used the crank. Turning it in the down position was addition - lift it up to the next detent and you were using subtraction.

Other than a neat mechanical/technical exercise...why?

quote:

Originally posted by sjtill:
I think rally navigators used to use them.

Agreed.

quote:

Originally posted by PHPaul:

Other than a neat mechanical/technical exercise...why?

An excellent device to calculate the cost of restoring a bulldozer.

I've watched several interesting videos on YouTube about the Curta.
https://www.youtube.com/result...ery=curta+calculator

Before integrated circuits made reasonably-sized calculators/computers possible, this is what you used … if you had the money. Other examples of mechanical computers are the Norden Bombsight:



Enigma machine:



Barr & Stroud rangefinder:

Time was when there were no computers or electronic calculators, and yet some people nevertheless thought mathematical calculations were important for any number of different reasons. You know, for stuff like building dams or railroads or airplanes. I was tempted to buy a Curta by a rally enthusiast, but it was just too expensive for a staff sergeant living in the D.C. area. What I really wanted shortly thereafter was the first HP (35?) calculator, but that was unthinkable. A year or so after coming back from Korea in 1972, TI came out with an affordable calculator (at $125), the SR-10, that had a π key and a square root function! I sold that some years later but still have the ones I bought after that.

quote:

What I really wanted shortly thereafter was the first HP (35?) calculator

Yes, it was the 35. My brother bought one circa 1974 or 75. It was some $400 then, a huge expense for a guy living on the GI Bill and a little bit of savings. (He has always been really good at that.) The equivalent in function calculator today is about one tenth of that.

quote:

Originally posted by egregore:
The equivalent in function calculator today is about one tenth of that.

Yes, and in 40 of today’s dollars versus 400 dollars then. According to the inflation calculator, $400 in 1972 when I heard about the HP-35 was equivalent to over $2400 today, plus I had a lot less disposable income then.

And thanks for the photo of the Norden bombsight. I’ve read about it countless times, but had no idea what it looked like. What was always a mystery to me, though, was the obsessive secrecy about it during the war, and yet there must have been countless examples that fell into German hands due to the number of aircraft that were shot down over the continent.

Mark 1 Fire Control Computer is a great analog machine. Version for 5” guns shown below.

It would calculate the correction in 16” fire control solution to correct for coriolis effect, among other things...



The Computer Mark 1 consists of four sections:

THE TRACKING SECTION
The Relative Motion Group combines the motions of OwnShip and Target into three rates of Relative Motion in relation to the Line of Sight, Elevation Rate, Deflection Rate, and Range Rate.
The Integrator Group uses these rates to generate changes of Target Position in Range, Elevation, and Bearing. These changes are continuously transmitted to the Director to position the telescopes and the Range Finder.
If the generated values of Target Position do not keep the sights on the Target, the operators in the Director press their Rate Control keys and turn their handwheels to keep the sights on the Target.
Turning the handwheels with the Rate Control keys closed sends Rate Control corrections to the Rate Control Group in the Computer.
The Rate Control Group applies these corrections to the values of Target Motion and sends the corrected values back to the Relative Motion Group.
The Deck Tilt Group computes the correction necessary to convert Director Train in the deck plane to Relative Target Bearing in the horizontal plane.
The Synchronize Elevation Group converts Director Elevation above the deck to Target Elevation above the horizontal.

THE PREDICTION SECTION
Uses the three Relative Motion Rates to compute the amount the guns must lead the Target. It computes two lead angles and a fuse setting order.
The Lead Angles include computation for the change in Target Position while the projectile is in the air and for the projectile's curved path. The Prediction Section computes the Target Position at the end of the Time of Flight and corrections for the effect of gravity, drift, wind, and changes in initial velocity on the projectile's path.
The Fuse Setting Order includes a correction for the change in Range during the time the projectile is being loaded.

THE TRUNNION TILT SECTION
Computes corrections for the effects of pitch and roll on the gun trunnions. The lead angles and the Trunnion Tilt Corrections are combined with Director Elevation and Train to form the two Gun Orders.

THE PARALLAX SECTION
Computes Train and Elevation Parallax Corrections for a horizontal distance of 100 yards along the fore and aft axis. Each gun or Director may use a fraction of each correction acording to its distance from the Reference Point.

http://www.navweaps.com/index_tech/tech-056.php

quote:

Originally posted by feersum dreadnaught:
Mark 1 Fire Control Computer is a great analog machine.

Another amazing device. Any idea how much training was required to operate it?

quote:

Originally posted by sigfreund:

quote:

Originally posted by feersum dreadnaught:
Mark 1 Fire Control Computer is a great analog machine.

Another amazing device. Any idea how much training was required to operate it?

It was relatively simple to operate. IIRC 8 operators stood around it each with specific data entry functions i.e. range data, speed, course, ete.. and the system output went directly to the gun mount. Now maintaining it is a different story.

In 1969. when I was at the U. of Michigan, there was this antique electric calculator on display on a table in the hall of the math building. Looked kind of like a wide carriage typewriter, perhaps 30" wide, but no paper, instead a series of rectangular cut-outs, that exposed numerals on rotating cylinders. I couldn't resist, after a few simple calculations, I entered a divide by zero problem just to see what would happen. Thing started spinning its wheels frantically, practically hopping in place. I kept expecting to start seeing smoke coming out of it. After about twenty minutes of waiting for it to give up, I pulled the plug to "reset" it. When I plugged it back in, it resumed its manic behavior. My first "hack!"

^^^^^^^^
Pulling the plug on mechanical devices seldom resets them.

Reminds me of a joke: “If I’m ever on life support, unplug me. Then plug me back in – see if that works.”

I have two of them, the large one and the small one.

I used them for Time-Speed-Distance rallies in the 70's and 80's. They are a true marvel. In the right hands (not mine) they are still competitive in the historical/vintage class.

Back in the day, if you had a Curta, a Halda Twin Master odometer and a Heuer Sebring stop watch you were well equipped.

Before the advent or electronic calculators, they were used by Engineers and Surveyors. They were more accurate than slide rules because of the number of decimal points that could be figured.

One of my old time friends specializes in rebuilding them.

My Dad brought me one from one of his overseas trip to Japan. I used to spend hours playing with it. It was sort of a modern version of the abacus.