Slide Rule

[Tim Hooper]

Seems to be an open secret that Neville Shute saw his prolific novel writing as a mere hobby, and that his 'real' career (under his given name of Neville Shute Norway) was that of aeronautical engineer.

He worked as a designer for Vickers and de Havilland, before becominmg a founder of the Airspeed company.

His biog (written in 1954, four years before his death) is the remarkable tale of his career - both from a technical point of view and as a businessman from the end of WW! to the 1950's.

Recommended!

tim

[Plummet]

Coincidence time. I was at college before calculators were allowed in exams, and so my trusty slide rule was my friend. Yesterday I used my slide rule again for the first time, probably since leaving college, because I was talking to a group about the history of computing.

I was also playing with a Comptometer. Can anyone explain to me how to use a comptometer to subtract and divide?

I read Slide Rule years ago. I concurr with your recommendation.

Plummet

[Alan Randall]

Nevil Shute Norway worked for Barns Wallis on the R100 airship as a stress calculator. His description of resolving the stresses in the main frames was interesting because what would take a computer seconds could take several people a fortnight.

[PatMc]

I always found it quicker & less prone to error to use log tables than a slide rule. Mine was used more often to draw straight lines although it was a handy place to hide cribbed formulae etc at exam time.

Never read any of Nevil Shute's books. SWMBO got a copy of "Landfall" from a charity shop, she thought it would interst me because it had a drawing of an aeroplane (Avro Anson) on the cover. I think I'll put it on my next read list.

[Fun Flyer]

Shute's "Trustee From The Toolroom" is another good read. As are most if not all his writing.

[kc]

I must read 'Slide Rule' again........

2 other books which are worth reading by aeromodellers are

New Science of Strong Materials

Structures or why things dont fall down.

both by J.E. Gordon. Published by Penguin Science. These dont sound like aero books but Prof Gordon was involved in research on planes during WW2 and his explanations of Hurricane , Mosquito problems and the wing failures of Fokker D7 are worth reading ( differs to other Fokker explanantions ) Also as a simple book to explain all sorts of structural things it is exceptional. Necessary reading for aeromodellers who are interested in light strong structures! Borrow it from the library and then you will want to buy your own copy!

[Geoff Jackson]

Still got my slide rule! When I did my O levels (just given my age away) we had to state on all the maths papers whether a slide rule was used! I think they also did that when calculators arrived. I may still have my first Texas Instruments scientific calculator as well.

Must read the Neville Shute books though.

[kc]

Plummets comptometer question.........I cannot find any info for certain, but on the old type that looks like a bus conductors ticket machine my wife seems to think you wind the handle forward until the bell rings and then wind it back! On the old National adding machines ( hand or electric) I seem to remember keeping the 'plus' button pressed down and pressing 'return' a number of times did something like subtract or divide.

But it's lost in the mists of time now but all I can remember is that you could use pounds shillings & pence machine for tons hundredweights and quarters using pounds for tons, shillings for hundredweight and threepence for a quarterhundredweight , sixpence for 2 quarters and ninepence for threequarters! You cannot do that with an electronic calculator!

[Phil Brooks]

I still remember being gobsmacked when watching The film of "Apollo 13" and the scene where the NASA experts are sitting around a table trying to work out how to get the astronauts back to earth. All are wielding slide rules, not even a calculator is in sight, let alone a computer of any description! Times sure have changed!

 

Back closer to original topic, Yes, some of Shute's books are a bit dated, his interest in spiritualism is a bit off putting to some, but his description of the in-fighting and rivalry in the R100/R101 competition is fascinating.

Edited By Phil Brooks on 18/04/2012 14:20:50

Edited By Phil Brooks on 18/04/2012 14:21:14

[PatMc]

Posted by Phil Brooks on 18/04/2012 14:17:37:

I still remember being gobsmacked when watching The film of "Apollo 13" and the scene where the NASA experts are sitting around a table trying to work out how to get the astronauts back to earth. All are wielding slide rules, not even a calculator is in sight, let alone a computer of any description! Times sure have changed!

There was a documentary recently explaining the licence between fact & drama used in the film. There were certainly pocket calculators generaly available in the early 1970's & office computors were quite common then to.

I remember a sequence in the film where Lovell (Tom Hanks) is showing people around the visitors centre. He points out how small & powerful their computor is as it only take up a single room. However I don't recall seeing slide rules in use but I suspect they may have been shown in the film just for dramatic effect since most people have no idea how inaccurate they are but they do look more technicaly impressive than a calculator to the layman.

[Jon Laughton]

Still have my original paperback copy of J E Gordon's 'New Science of Strong Materials' that I bought in 1977 as a recommended 'pre-reader' for the university course i started that Autumn - I must dig it out for another read. Thanks for the prompt kc!

[Erfolg]

Patmac is certainly correct n stating that in the early 70s, the calculator had arrived. A single Hewlett Packard was available in our office for all to use. Sinclair was marketed at the college and private user, using Reverse Polish Notation, which our lecturer made great play of being far more logical from an arithmetic view point. In my case I bought a Commodore 8120, as it was a little more expensive but simple to use.

On the subject of slide rules, I have also still got my own, a Faber Castell. A true work of art, made from laminated wood, brass strip, with plastic faces. Al supplied in a clear front case with a green rear. The outstanding virtue of the investment, that all the basic relationships of maths and engineering science were on the rear of the rule. I guess the true virtue of the slide rule, is that you were not drawn into the temptation of providing an answer to 5 or so decimal points, as is common with calculators. You thought about the viable level of accuracy.

As with most people, I used my slide rule mainly for drawing lines and measuring.

[PatMc]

I too still have my slide rule, it's in it's original case somewhere in the attic. They always looked more impressive than calculators. The poseurs at college used to carry the 6" versions in their top pocket. The rest of us knew them as "guessing sticks" & preferred using log tables.

[Andy Palmer]

I live just north of Portsmouth where Airspeed were based so there are some local connections. A couple of years ago the guy that lives 3 doors away was telling me that the previous owners of his house were friends of Nevil Shute and he often used to visit the house. He also told me that Norway Road is named after him, and of course Nevil Shute Road, both next to the old Portsmouth Airport, now sadly gone. He lent me a Nevil Shute book to read (forget which one) which was fascinating and I keep meaning to search out some of his others.

On the subject of slide rules, I used to love my long gone British Thornton one and must have spoken about it to my wife, as on my 60th birthday she presented me with a slide rule she had spotted in a charity shop. I agree that log tables are of course more accurate and I used to enjoy using them but somehow the 'magic stick' always had a special appeal!

[Olly P]

Must dig out my slide rule. I don't use it often, but love having it on my desk to confuse young engineers with.....

[buster prop]

Still got my slide rule as well! Mine's a BRL 'Academy' which I used back in the late '60's when doing HNC as a day release course (remember those?). My youngest son was intrigued by it, I showed him how to multiply, divide, find square roots, sines, tangents and reciprocals all without needing a battery. He was impressed but doubted it's accuracy because of the non-linear logarithmic scales. I also read a few Nevil Shute books, one I particularly remember is 'No Highway' about metal fatigue in a ficticious airliner, called the Reindeer, I think. The mention of comptometers rang a bell, there was once a firm called Sumlock which made an early electronic adding machine which was also called a comptometer. The Nevil Shute books I've read are 'A Town Like Alice', 'On the Beach' and 'Slide Rule'. He was an under rated author in my opinion.

[kc]

Jon L. It's the Structures book, not the New Science Strong Materials book, that contains the Fokker D8 explanantion ( not D7. my error ) which is very relevent to aeromodelling.

Bletchley Park contains a computer museum that has every type of calculator device as well as computors. You could see a huge range of devices that we all remember. The very knowledgeable staff would surely know how Plummets comptometer works. It's an extra cost museum within Bletchley Pk and only open certain times. When I went last year they were looking for working radio valves etc if anyone has any to donate.

By 1973 electronic calculators ( mains power) were normal office equipment so NASA would have had them much earlier than that.

[Geoff Jackson]

I was at Bletchley Park as an apprentice with the Board of Trade when GCHQ was till there. I never knew till 10 years ago what happened there - it was still secret. I still have my official secrets letter. i've been back to see the Bombes and Enigma and realised our old social club was the hut Alan Turing was in. I had the time of my life there and now realise what a huge importance this small place was. You have to visit to realise the impact it had on the war's outcome. I'd recommend it to anyone and will be visiting it again. They still have to fight for funding to protect it from all our shortsighted political parties!!

[Erfolg]

Well I have had a look for my slide rules, my treasured Faber Castell and a few British Thorntons (one company issue before calculators were standard issue). Of course missing without trace. I assume in the loft, with a hundred weight off text books. I do threaten to get them down from time to time, then realise I have no room for my recreational (aircraft0 books, never mind books which were essentially reference.

With respect to the D8 wing failures, if the suggestion was aeroelasticity, it seems unlikely with the D8. Other WW1 aircraft probably did including the Handley Page 400 and the lower wing on both the Albatros and Nieuports of the 27 type.

It is more probable that it ws poor workmanship due to subcontractors planing away parts of the spars to fit the wing ribs.

The plywood covering, should have been an improvement on most WW1 wings, irrespective of the bracing wires.

There has also been suggestions that the ailerons could have fluttered, yet again, this must have been an issue for most WW1 fighters, other than the D8 had possibly beefier ailerons than most, moving the CG of the ailerons back, certainly relative to many open structure types.

[Plummet]

Posted by kc on 18/04/2012 12:59:05:

I must read 'Slide Rule' again........

2 other books which are worth reading by aeromodellers are

New Science of Strong Materials

Structures or why things dont fall down.

both by J.E. Gordon. Published by Penguin Science...<snip>

I second this recommendation. They were recommended reading when I was at college - and unlike a lot of the stuff I did or didn't learn there, stuff from these books still comes to mind.

Plummet

[kc]

Prof Gordons books probably deserve a seperate thread on 'Book Club' ( didnt realise it existed when I posted -sorry to interrupt your thread Tim ) and I will do that in due course All i will say here is they are very easy books to read with excellent illustrations.

You should read Prof Gordons full explanation of the D8 wing failure -it's completely different to Erfolgs view. Basically the Prof's explanantion is Anthony Fokker realised that the Centre of Flexure was a long way behind Centre of Pressure & much too near mid chord,this caused the wing to twist as it bent. A sort of aileron reversal. What the pilot did made matters worse until the wing failed. Therefore strengthening the rear spar ( after first crashes ) made matters even worse so the answer was to REDUCE the strength of the rear spar. My simple version has left out a few facts so read the very full account in 'Structures' .

[Erfolg]

The D8 wing failure has been attributed to many features of the wing and has been the subject to many explanations by many leaned bodies and individuals.

The rear spar strengthening was the explanation of Anthony Fokker. A number of learned people have dismissed this explanation as AF endeavoured to lay the blame at the door of German Luftwaffe engineers, who had requested this feature. It also, allowed AF to have been the first individual to lay claim to have recognised aeroelasticity as a phenomena, retrospectively in "The Flying Dutchman".

On the other hand, a number of wings which had been pulled from aircraft, which had been received for service, failed at significantly less than 6g.

On the other hand, wings closely supervised during construction failed at +6g.

Examination of a number of wings submitted for service, by dismantling, were found to have major deficiencies in construction, particularly of the front spar.

The wings were then futher modified and the aircraft redesignated, for reasons of politics and moral. AF not addmitting fault as his design, the German Engineers feeling they were slighted and the need to gain acceptence of a particular aircraft.

The aeroelasticity was I investigated by Dr Bublitz, and he did claim some torsional twisting at the tips. I understand by others assessment if the mainspar was below specification

I personally suspect it was a number of issues. The weakened mainspar being one of the issues. Though I do think we need to bare in mind the speeds being flown at, even in a dive and pulling out.

By the standards of the day, the wing was very thick, due to copying Hugo Junkers design. The ply covering being far stiffer to torsion than simple cloth stitched wing.

I guess at this juncture we will never really know, if aeroelasticity was an inherent design fault, or due to manufacturing issues, or the failure was a bending failure due to overstressing, again due to a faulty mainspar.

[PeD]

Re-Plummets request "comptometer"

I worked for Bell at Hanger Lane as a repair tech, when young and foolish.

The Sumlock comps. had a + & - rocker switch which you preselected to add and take away from the mechanically stored "memory". I think it wasn't until the "Anita", the first electronic machine came out from Bell that true divide was possible.

Whilst we techies had some neat tricks to test all functions of the machine, the girls in the Mars factory accnts. section could do amazing things with theres.

And with that I'm going to lie down in a dark room and have a cold shower.

Cheers