Slide Rule Lecture...

[Martin Brown]

Went to an interesting talk stemming from lockdown (when he really
started collecting in earnest) where a former ICI executive showed off
his extensive slide rule collection and demonstrated to the youngsters
in the local university ChemSoc audience how to use a slide rule.

Presentation was a little odd using OHP slides rather than PPT.

He even had some \"chemistry\" slide rules that had atomic masses encoded
on them and the ability to solve redox and stochiometric composition
equations.

https://www.sliderulemuseum.com/Circular/Graphic_Chemical_Predictor_DonatedByNormanDFultonFamily.jpg

The one with chemical masses on must be incredibly rare. I saw one in
the flesh at his talk but I can\'t find an example anywhere on the ISRM
collection of circular slide rule.

The audience profile was very bimodal - students who had never even seen
a slide rule before and friends and associates of the lecturer who had
used them extensively early on in their own careers.

I learnt one new trick in the lecture (due to Newton) - how to solve a
cubic polynomial equation using three identical slide rules equally
spaced on a table and a straight edge - extremely cunning trick.

He had examples of ones used on the Manhattan project, Concorde design
and his pride and joy was an 8\" Gilson circular slide rule equivalent to
a straight one 7\' long! Identical to this one (possibly is this one)

https://www.sliderulemuseum.com/Circular/Gilson_Atlas_8inchCircularSlideRule.jpg

Needs incredibly good eyesight to use it. He also had Fowlers pocket
watch style slide rule where the winders move the verniers inside a
glass fronted case (allegedly once belonging to J.J. Thompson).

https://www.sliderulemuseum.com/Rarities/Fowlers_MagnumLongScaleCalculator_RodLovetteCollection_Variation1.jpg

This one would even be on topic here!
https://www.sliderulemuseum.com/Circular/Amphenol_CircularSlideRule_RF_SmithChart.jpg

And of course a classic linear workhorse the Picket S226

https://www.sliderulemuseum.com/Pickett/S226_Pickett_Model_3.jpg

Apparently MIT and a couple of other top universities have started
running freshman slide rule courses to help students grasp the idea of
\"right order of magnitude\" in physical problems.

You can waste ages on the ISR museum site :
https://www.sliderulemuseum.com

BTW one of this guy\'s other claims to fame was that he solved the
problem of polycarbonate fighter aircraft canopies crazing due to UV
exposure. The bad news is that what he did is still a classified secret.


--
Martin Brown

 

[Ralph Mowery]

In article <tvcfmd$551n$1@dont-email.me>, \'\'\'newspam\'\'\'@nonad.co.uk
says...

The audience profile was very bimodal - students who had never even seen
a slide rule before and friends and associates of the lecturer who had
used them extensively early on in their own careers.

The slide rule was all we had in 1970 when I was taking an electronics
engineering course. I doubt I could use one now other than multiplying
and square and cube roots. I still have one around the house but have
not used it in many years..
The CRC book was also a go to thing of the past.

 

[Jan Panteltje]

On a sunny day (Tue, 21 Mar 2023 14:41:14 +0000) it happened Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tvcfmd$551n$1@dont-email.me>:

Went to an interesting talk stemming from lockdown (when he really
started collecting in earnest) where a former ICI executive showed off
his extensive slide rule collection and demonstrated to the youngsters
in the local university ChemSoc audience how to use a slide rule.

Presentation was a little odd using OHP slides rather than PPT.

He even had some \"chemistry\" slide rules that had atomic masses encoded
on them and the ability to solve redox and stochiometric composition
equations.

https://www.sliderulemuseum.com/Circular/Graphic_Chemical_Predictor_DonatedByNormanDFultonFamily.jpg

The one with chemical masses on must be incredibly rare. I saw one in
the flesh at his talk but I can\'t find an example anywhere on the ISRM
collection of circular slide rule.

The audience profile was very bimodal - students who had never even seen
a slide rule before and friends and associates of the lecturer who had
used them extensively early on in their own careers.

I learnt one new trick in the lecture (due to Newton) - how to solve a
cubic polynomial equation using three identical slide rules equally
spaced on a table and a straight edge - extremely cunning trick.

He had examples of ones used on the Manhattan project, Concorde design
and his pride and joy was an 8\" Gilson circular slide rule equivalent to
a straight one 7\' long! Identical to this one (possibly is this one)

https://www.sliderulemuseum.com/Circular/Gilson_Atlas_8inchCircularSlideRule.jpg

Cool! spiral scale

Needs incredibly good eyesight to use it. He also had Fowlers pocket
watch style slide rule where the winders move the verniers inside a
glass fronted case (allegedly once belonging to J.J. Thompson).

https://www.sliderulemuseum.com/Rarities/Fowlers_MagnumLongScaleCalculator_RodLovetteCollection_Variation1.jpg

This one would even be on topic here!
https://www.sliderulemuseum.com/Circular/Amphenol_CircularSlideRule_RF_SmithChart.jpg

And of course a classic linear workhorse the Picket S226

https://www.sliderulemuseum.com/Pickett/S226_Pickett_Model_3.jpg

I had an Aristo Studio in my school days...

 

[Mike Monett VE3BTI]

Martin Brown <\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

And of course a classic linear workhorse the Picket S226

https://www.sliderulemuseum.com/Pickett/S226_Pickett_Model_3.jpg

A long time ago, circa 1955, I proposed to Pickett that they replace the
flat window with a circular one to magnify the readings and get more
accurate settings. About a year later, I saw slide rules with circular
windows on sale and I bought one. It worked so well I tossed my old ones in
the garbage and used the new one.

I have not been able to find any example of a slide rule with a circular
window in any of the historical sites.

Apparently MIT and a couple of other top universities have started
running freshman slide rule courses to help students grasp the idea of
\"right order of magnitude\" in physical problems.

You can waste ages on the ISR museum site :
https://www.sliderulemuseum.com

BTW one of this guy\'s other claims to fame was that he solved the
problem of polycarbonate fighter aircraft canopies crazing due to UV
exposure. The bad news is that what he did is still a classified secret.

I had a polycarbonate window in my Piper PA-46 Malibu, N4360V, and had no
problem with crazing.

http://www.jetphotos.net/viewphoto.php?id=5874208&nseq=0

I also had a Cessna 152 with a poly window and no problem with crazing. It
was for any of my employees who wanted to learn how to fly.

Poly windows have been used in aircraft windows since before WWII. As far
as I can tell, there have never been any problems with canopies crazing due
to UV exposure.

Polymethyl methacrylate (Plexiglas)

The material was developed in 1928 in several different laboratories by
many chemists.

Historically, PMMA was an important improvement in the design of aircraft
windows, making possible such iconic designs as the bombardier\'s
transparent nose compartment in the Boeing B-17 Flying Fortress.

From early on Plexiglas found a market in aviation, as the alternatives
were either flammable or too heavy.

https://aviation.stackexchange.com/questions/31423/when-airplanes-first-
got-windows-what-material-was-used





--
MRM

 

[Bob Engelhardt]

On 3/21/2023 1:25 PM, Mike Monett VE3BTI wrote:

I had a polycarbonate window in my Piper PA-46 Malibu, N4360V, and had no
problem with crazing.
[...]

Poly windows have been used in aircraft windows since before WWII. As far
as I can tell, there have never been any problems with canopies crazing due
to UV exposure.

Polymethyl methacrylate (Plexiglas)

[...]

Plexiglass is acrylic, not polycarbonate.

 

[Tauno Voipio]

On 22.3.2023 15.50, Bob Engelhardt wrote:

On 3/21/2023 1:25 PM, Mike Monett VE3BTI wrote:
I had a polycarbonate window in my Piper PA-46 Malibu, N4360V, and had no
problem with crazing.
[...]
Poly windows have been used in aircraft windows since before WWII. As far
as I can tell, there have never been any problems with canopies
crazing due
to UV exposure.

Polymethyl methacrylate (Plexiglas)

[...]

Plexiglass is acrylic, not polycarbonate.

Malibu is pressurized, and it may need heftier material than PMMA
for the windows. My old PA28RT201T Turbo arrow had PMMA (plexi)
windows.

--

-TV

 

[Mike Monett VE3BTI]

Bob Engelhardt <BobEngelhardt@comcast.net> wrote:

Poly windows have been used in aircraft windows since before WWII. As
far as I can tell, there have never been any problems with canopies
crazing due to UV exposure.

Polymethyl methacrylate (Plexiglas)

[...]

Plexiglass is acrylic, not polycarbonate.

Plexiglass is most assuredly not acrylic. Acrylic shatters, which is why it
is so hard to drill. It would be a disaster in aircraft. Even a small bird
strike would disable the pilot.

Plexiglass is polycarbonate and has been used in aircraft windshields since
before WWII. For example, in the DC-3, which is still flying today. It is
much stronger than acrylic, and takes much higher velocities to cause
damage. These velocities are not normally reached in civilian aircraft.

Military aircraft use bulletproof glass in the windshield, and plexiglass
for the canopy. Civilian jets use a multilayer combination of glass and a
shock absorbing layer. They are intensively tested before certification.

Please note, I have PLONKED you for a long time. The only reason I am
replying to you is someone included your post in a new one. I will probably
not see your reply and will not answer.


--
MRM

 

[Mike Monett VE3BTI]

Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote:

Malibu is pressurized, and it may need heftier material than PMMA
for the windows. My old PA28RT201T Turbo arrow had PMMA (plexi)
windows.


-TV

Just make it thicker.



--
MRM

 

[Carl]

On 3/22/23 21:57, Mike Monett VE3BTI wrote:

Bob Engelhardt <BobEngelhardt@comcast.net> wrote:

Poly windows have been used in aircraft windows since before WWII. As
far as I can tell, there have never been any problems with canopies
crazing due to UV exposure.

Polymethyl methacrylate (Plexiglas)

[...]

Plexiglass is acrylic, not polycarbonate.

Plexiglass is most assuredly not acrylic. Acrylic shatters, which is why it
is so hard to drill. It would be a disaster in aircraft. Even a small bird
strike would disable the pilot.

Plexiglass is polycarbonate and has been used in aircraft windshields since
before WWII. For example, in the DC-3, which is still flying today. It is
much stronger than acrylic, and takes much higher velocities to cause
damage. These velocities are not normally reached in civilian aircraft.

Military aircraft use bulletproof glass in the windshield, and plexiglass
for the canopy. Civilian jets use a multilayer combination of glass and a
shock absorbing layer. They are intensively tested before certification.

Please note, I have PLONKED you for a long time. The only reason I am
replying to you is someone included your post in a new one. I will probably
not see your reply and will not answer.

Plexiglas is a trademarked name for polymethylmethacrylate, definitely
an acrylic. Lexan is an early trademarked name for a family of
polycarbonates, most commonly made from bisphenol A. A bit of googling
or reading at Wikipedia (
https://en.wikipedia.org/wiki/Poly(methyl_methacrylate) and
https://en.wikipedia.org/wiki/Polycarbonate ) will confirm this.

--
Regards,
Carl

 

[Dave Platt]

In article <XnsAFCFDF5795BA5idtokenpost@88.198.57.247>,
Mike Monett VE3BTI <spamme@not.com> wrote:

Plexiglass is acrylic, not polycarbonate.

Plexiglass is most assuredly not acrylic. Acrylic shatters, which is why it
is so hard to drill.

Numerous references (plastic dealers, and the company which holds the
Plexiglas® trademark) disagree with you.

https://www.plexiglas.de/en/home
https://plasticsheetsshop.co.uk/the-difference-between-acrylic-and-plexiglass/
https://www.acplasticsinc.com/informationcenter/r/plexiglass-vs-plexiglas
https://www.acmeplastics.com/cast-vs-extruded

>Plexiglass is polycarbonate

Can you cite specific technical references which support this? All
the references I have ever seen, state that plexiglass and
polycarbonate are two different materials, with different properties.
LEXAN and Makrolon are the trade namea I\'ve usually seen associated
with polycarbonate, although there are plenty of others.

https://www.polymershapes.com/lexan-vs-plexiglass/

 

[Martin Brown]

On 23/03/2023 01:57, Mike Monett VE3BTI wrote:

Bob Engelhardt <BobEngelhardt@comcast.net> wrote:

Poly windows have been used in aircraft windows since before WWII. As
far as I can tell, there have never been any problems with canopies
crazing due to UV exposure.

Polymethyl methacrylate (Plexiglas)

[...]

Plexiglass is acrylic, not polycarbonate.

Plexiglass is most assuredly not acrylic. Acrylic shatters, which is why it
is so hard to drill. It would be a disaster in aircraft. Even a small bird
strike would disable the pilot.

Plexiglass was originally a brand name for a toughened cross linked
Acrylic. The cheaper grades are more thermoplastic and less strong.

https://en.wikipedia.org/wiki/Poly(methyl_methacrylate)

Today you can\'t be sure what material sold under \"Plexiglass\" brandname
means any more it has in some places become \"*any* water clear plastic\".

ICI\'s Perspex and Du Pont\'s Lucite brands were the main players in water
clear acrylic. ICI now absorbed into Lucite International.

Plexiglass is polycarbonate and has been used in aircraft windshields since
before WWII. For example, in the DC-3, which is still flying today. It is
much stronger than acrylic, and takes much higher velocities to cause
damage. These velocities are not normally reached in civilian aircraft.

It is a form of PMMA but more highly cross linked than the ordinary
thermal plastic extruded sheets.

Military aircraft use bulletproof glass in the windshield, and plexiglass
for the canopy. Civilian jets use a multilayer combination of glass and a
shock absorbing layer. They are intensively tested before certification.

The work on using Polycarbonate for the F16 canopy is still classified
in the UK but the US are a bit more cavalier these days. This URL of
declassified military research details some of the then classified
experiments on making Polycarbonate withstand the environmental rigours
of flying high UV and weather. Some clever chemistry was involved.

https://apps.dtic.mil/sti/pdfs/ADB061170.pdf

I particularly like the front page \"subject to export control laws and
various threats of fines\" section which hasn\'t been redacted. Fairly
pointless if you put the thing onto a server and let Google index it!

The redacted bits such as they are haven\'t been done very well either!

The key difference between clear acrylic and polycarbonate is that at
Mach 1+ a birdstrike often compromises acrylic but just bounces off
polycarbonate - it is much more of an engineering plastic with more
strength and toughness than acrylic for a given thickness and weight
really matters in a jet fighter.

--
Martin Brown

 

[Martin Brown]

On 21/03/2023 16:23, Jan Panteltje wrote:

On a sunny day (Tue, 21 Mar 2023 14:41:14 +0000) it happened Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tvcfmd$551n$1@dont-email.me>:

Went to an interesting talk stemming from lockdown (when he really
started collecting in earnest) where a former ICI executive showed off
his extensive slide rule collection and demonstrated to the youngsters
in the local university ChemSoc audience how to use a slide rule.

Presentation was a little odd using OHP slides rather than PPT.

He even had some \"chemistry\" slide rules that had atomic masses encoded
on them and the ability to solve redox and stochiometric composition
equations.

https://www.sliderulemuseum.com/Circular/Graphic_Chemical_Predictor_DonatedByNormanDFultonFamily.jpg

The one with chemical masses on must be incredibly rare. I saw one in
the flesh at his talk but I can\'t find an example anywhere on the ISRM
collection of circular slide rule.

The audience profile was very bimodal - students who had never even seen
a slide rule before and friends and associates of the lecturer who had
used them extensively early on in their own careers.

I learnt one new trick in the lecture (due to Newton) - how to solve a
cubic polynomial equation using three identical slide rules equally
spaced on a table and a straight edge - extremely cunning trick.

He had examples of ones used on the Manhattan project, Concorde design
and his pride and joy was an 8\" Gilson circular slide rule equivalent to
a straight one 7\' long! Identical to this one (possibly is this one)

https://www.sliderulemuseum.com/Circular/Gilson_Atlas_8inchCircularSlideRule.jpg

Cool! spiral scale

It took me a couple of minutes to get the hang of it but you can get
nearly 5 sig fig multiplies once you figure out how to set up the two
numbers to be multiplied. Two fine lines set the master to 1 and the
other to x, then move the master to the other number and the slave moves
with it. It really was quite something to behold.

The smaller very finely worked pocket watch one was even more impressive
but I needed two pairs of glasses on to read it!

Needs incredibly good eyesight to use it. He also had Fowlers pocket
watch style slide rule where the winders move the verniers inside a
glass fronted case (allegedly once belonging to J.J. Thompson).

https://www.sliderulemuseum.com/Rarities/Fowlers_MagnumLongScaleCalculator_RodLovetteCollection_Variation1.jpg

This one would even be on topic here!
https://www.sliderulemuseum.com/Circular/Amphenol_CircularSlideRule_RF_SmithChart.jpg

And of course a classic linear workhorse the Picket S226

https://www.sliderulemuseum.com/Pickett/S226_Pickett_Model_3.jpg

I had an Aristo Studio in my school days...

Mine was a random generic plastic one. In my school days I could pretty
much do 3 sig fig mental arithmetic and just scribbled SR in the
margins. I had to get a calculator at university - correct answers in
crystallography were at least 5 sig figures and sometime more.

My first calculator was a TI SR-51A.

--
Martin Brown

 

[Jan Panteltje]

On a sunny day (Thu, 23 Mar 2023 11:17:18 +0000) it happened Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tvhcg8$14a2p$1@dont-email.me>:

On 21/03/2023 16:23, Jan Panteltje wrote:
On a sunny day (Tue, 21 Mar 2023 14:41:14 +0000) it happened Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tvcfmd$551n$1@dont-email.me>:

Went to an interesting talk stemming from lockdown (when he really
started collecting in earnest) where a former ICI executive showed off
his extensive slide rule collection and demonstrated to the youngsters
in the local university ChemSoc audience how to use a slide rule.

Presentation was a little odd using OHP slides rather than PPT.

He even had some \"chemistry\" slide rules that had atomic masses encoded
on them and the ability to solve redox and stochiometric composition
equations.

https://www.sliderulemuseum.com/Circular/Graphic_Chemical_Predictor_DonatedByNormanDFultonFamily.jpg

The one with chemical masses on must be incredibly rare. I saw one in
the flesh at his talk but I can\'t find an example anywhere on the ISRM
collection of circular slide rule.

The audience profile was very bimodal - students who had never even seen
a slide rule before and friends and associates of the lecturer who had
used them extensively early on in their own careers.

I learnt one new trick in the lecture (due to Newton) - how to solve a
cubic polynomial equation using three identical slide rules equally
spaced on a table and a straight edge - extremely cunning trick.

He had examples of ones used on the Manhattan project, Concorde design
and his pride and joy was an 8\" Gilson circular slide rule equivalent to
a straight one 7\' long! Identical to this one (possibly is this one)

https://www.sliderulemuseum.com/Circular/Gilson_Atlas_8inchCircularSlideRule.jpg

Cool! spiral scale

It took me a couple of minutes to get the hang of it but you can get
nearly 5 sig fig multiplies once you figure out how to set up the two
numbers to be multiplied. Two fine lines set the master to 1 and the
other to x, then move the master to the other number and the slave moves
with it. It really was quite something to behold.

The smaller very finely worked pocket watch one was even more impressive
but I needed two pairs of glasses on to read it!

Needs incredibly good eyesight to use it. He also had Fowlers pocket
watch style slide rule where the winders move the verniers inside a
glass fronted case (allegedly once belonging to J.J. Thompson).

https://www.sliderulemuseum.com/Rarities/Fowlers_MagnumLongScaleCalculator_RodLovetteCollection_Variation1.jpg

This one would even be on topic here!
https://www.sliderulemuseum.com/Circular/Amphenol_CircularSlideRule_RF_SmithChart.jpg

And of course a classic linear workhorse the Picket S226

https://www.sliderulemuseum.com/Pickett/S226_Pickett_Model_3.jpg

I had an Aristo Studio in my school days...

Mine was a random generic plastic one. In my school days I could pretty
much do 3 sig fig mental arithmetic and just scribbled SR in the
margins. I had to get a calculator at university - correct answers in
crystallography were at least 5 sig figures and sometime more.

My first calculator was a TI SR-51A.

I do not remember the make, but bought my first calculator in London
around .. now let me think... 1976? tried it and did some simple things
2 x 4 turned out to be different from 8..
So brought it back, \'Oh the man set, its made in the UK,
here is one made in the US\', that one worked!
My first computah I bought was a Sinclair ZX80 in the very early eighties
(had worked with a PDP10 or 11 before in 1978 or so, knew about Unix and some guys had a Motorola maxboard at work,
and I had designed a hardware video digitizer back then).
Had Brian Kernighan and Dennis M. Ritchie \'The C Programming Language\' too.

At that time I had the TV repair shop, added a thermal printer and printed receipts and
stuff... Wrote the code and made an RS232 interface for the printer.
Then when ZX81 came out things really took of, added memory, I/O board, EPROM programmer board,
modem board and finally wrote a CP/M clone for it so I could run programs from the CP/M user club
they were on Viditel, an internet predecessor:
https://historiek.net/viditel-eerste-publieke-onlinedienst-van-nederland/143609/

https://panteltje.nl/panteltje/z80/index.html
https://panteltje.nl/panteltje/z80/system14/index.html
https://panteltje.nl/panteltje/z80/system14/diagrams/index.html
By that time I was working with IBM stuff for a big company,
designing ISA cards and embedded stuff.
But the ZX81 stayed my home computer for a long time... added a IBM keyboard, and a 5 1/4 inch floppy drive
In 1998 I found a CD with SLS Linux that came with some magazine
and from then on it was Linux only.
No problem I had a nice Unix book too, just took off! Free gcc compiler!

I did have a PC with Microsoft win 3.1 or something and trumpet winsock for the internet at that time...
And Free Agent for Usenet.
No such thing for Linux existed, so I wrote NewsFleX (as Unix and C exercise):
https://panteltje.nl/panteltje/newsflex/index.html
still using it, right now, ported to a Raspberry Pi4.

Linux has been polluted (to say the least) by RatHead\'s systemd,
was looking for a way to get rid of it for the Raspberry Pi4 I have,
There is a lot online.

What happened to that calculator and slide rule I do not know, I did donate a lot of stuff when moving house..
Still have boxes full of electronics stuff...

 

[Bob Engelhardt]

On 3/22/2023 9:57 PM, Mike Monett VE3BTI wrote:

[...]
Please note, I have PLONKED you for a long time. The only reason I am
replying to you is someone included your post in a new one. I will probably
not see your reply and will not answer.

Thanks. I will appreciate your not answering.

(Would someone do me the favor of quoting this so he will see it. Thanks)