Thread: Making Big Wooden Propellers

Anyone seen the movie 'Numbers'

Originally Posted by rwbuild

Anyone seen the movie 'Numbers'

I loved the film “Hidden Figures” about three brilliant African-American women and the flight of John Glenn.

Originally Posted by Lappa

I loved the film “Hidden Figures” about three brilliant African-American women and the flight of John Glenn.

They were some of the human computers the book was based on. https://www.newscientist.com/article...nasas-success/

Thats my seniors moment, I did mean 'Hidden Figures', brilliant

Amazing video. Ingenuity and design.
Some of those workers looked like kids and there were a whole heap of them.
Thank you!!

Originally Posted by Chris Parks

I read a very interesting book about the Langley operation recently. Apparently they ransacked all the educational facilities in the US looking for human computers (mostly women) and the book I read looked at the Negro female human computers who were part of it. It seems strange to see mathematicians called human computers but they were.

The first atomic bombs and many WWII code breaker calculations used human computers - mostly women.

In most cases the rooms full of women had no clue what they were involved with, they were just given a bunch of numbers and told to perform certain calculations (+ - x / etc) and pass them on.

The first Atomic bomb calculators were managed and quality controlled by the later Nobel prize winner, Richard Feyman, at a large high security military facility . Feynman was in his early 20's when he set up this computer and also later adopted punch card systems for use in the calculations. He worked out a generic system for the "computer" to calculate things using his computer that left him lots of free time to goof off. One of his tricks was to break into Army safes and secure areas and leave notes with "Igor was here" to show how crap the security was.

I recently read the history of the Aussie code breakers in WWII pacific theatre. In it they describe the computer facility in Melbourne staffed mainly by women that did a lot of code breaking work along teh lines of Bletchley Park in the UK.

The other skill needed was real time radio interception at which the aussies became the experts in the pacific theatre. When McArthur invaded the Philippines he took no Aussie troops and left them behind to clean up New Guinea etc, he took no Aussie Female computers but he did take American females, but he did take a group of Aussie radio interceptors including a woman. These guys had to write down the radio traffic and pass it on and would hit the beaches within hours of landings and set up radio reception bases on the backs of trucks and start passing on the info to field commanders.

Code breakers by Craig Collie - a 400 page, fairly technical book with a fascinating insight into what went on and it covers most of the major events in the Pacific theatre, worth a read in my book.

Re "computers" being human computers. That was the normal meaning till electronic computers became widespread. Another interesting story can be found in Nevil Shutes autobiography "Sliderule" where he describes how the computers would calculate the stresses in the ring frames of the airship (R100) that they were designing. Basically they would guess what the stress in one girder was then calculate around the ring (and bracing wires) and if they got back to the start, and their initial estimate was right then it was all good. If not, make a new guess and start again. Each set of calculations would take a couple of days and there were two guys doing it in parallel so if they got different answers at the end of the couple of days they could go back and try to track down where they dropped the minus sign or whatever. It took months to do each ring frame.

There was also a thing on Radio National Science Show in the last few days about a guy (Lewis Fry Richardson) who was trying to do weather prediction calculations in the first half of the 20th century. He worked out the maths to predict up coming weather (from past weather) and then concluded that to do it fast enough to be useful would take about 60000 computers (people). The impression I got from the radio show was that this was considered as a plausible project, until he realised he was a bit out in his numbers and would need more than 200 thousand computers! )

Regards
SWK

It's not just computation that computers have had a big impact on.

A friend of mine did his PhD in theoretical nuclear physics in the early 60's, His superviser used a large room set up with dozens of long trestle tables on which rolls of butcher paper were unfurled. The Equations were often many metres long and written out on the butchers paper and when they ran out of room on one piece of paper they moved to the next table - they left it all laid out so multiple checks of everything could be performed. It would taken him many weeks to perform some of the calculations and he spent over 3 years doing this before he got some results worth publishing and another couple of years to write it all up into a thesis.

In the late 80s the algebraic capability of computers improved so rapidly whereby he was able to use a computer program called Mathematica to solve his PhD equations in minutes. Like most situations it took him far longer to enter and check the inputs than the computer took to solve the equations.

Originally Posted by swk

Re "computers" being human computers. That was the normal meaning till electronic computers became widespread. Another interesting story can be found in Nevil Shutes autobiography "Sliderule" where he describes how the computers would calculate the stresses in the ring frames of the airship (R100) that they were designing. Basically they would guess what the stress in one girder was then calculate around the ring (and bracing wires) and if they got back to the start, and their initial estimate was right then it was all good. If not, make a new guess and start again. Each set of calculations would take a couple of days and there were two guys doing it in parallel so if they got different answers at the end of the couple of days they could go back and try to track down where they dropped the minus sign or whatever. It took months to do each ring frame.

There was also a thing on Radio National Science Show in the last few days about a guy (Lewis Fry Richardson) who was trying to do weather prediction calculations in the first half of the 20th century. He worked out the maths to predict up coming weather (from past weather) and then concluded that to do it fast enough to be useful would take about 60000 computers (people). The impression I got from the radio show was that this was considered as a plausible project, until he realised he was a bit out in his numbers and would need more than 200 thousand computers! )

Regards
SWK

Neville Shute's autobiography Slide Rule was a very interesting book and I would recommend it to everyone to read. Not overly technical but the author explained all the issues really well. Sometimes they would work for a week on one computation, get the wrong answer and have to start again.

The making of the atomic bomb was also an interesting book tracing the start from the late 19th century right through to the dropping in Japan and all the people and how they came to be involved. The American government took a lot of convincing to go ahead and it was a very compressed project towards the end with some dissension in the scientific ranks due to ethics reasons.

Amazing video, thanks for posting. Can you imagine the pressure on everyone during the glue-up, I'm sure some choice words were often quoted

Nice to watch thanks Chris. I liked these clamps they were using at the 2.20 mark . Double sided like a hair pin. They would not be to hard to make and give good even pressure with out the flexing sash clamps can give at times for panel glueing like that .
IMG_8194.JPG

Originally Posted by auscab

Nice to watch thanks Chris. I liked these clamps they were using at the 2.20 mark . Double sided like a hair pin. They would not be to hard to make and give good even pressure with out the flexing sash clamps can give at times for panel glueing like that .
IMG_8194.JPG

You could do that with a very slight radius in one of the legs like the cambered cauls some people use...