Nav Tools

--> Most recent Blog

Comments Policy
Maths trivia
Search this site
RSS feed for Stu Savory's Blog RSS Feed

Stu Savory School report for Stu Savory
Eunoia, who is a grumpy, overeducated, facetious, multilingual ex-pat Scot, blatantly opinionated, old (1944-vintage), amateur cryptologist, computer consultant, atheist, flying instructor, bulldog-lover, Beetle-driver, textbook-writer, long-distance biker, geocacher and blogger living in the foothills south of the northern German plains. Not too shy to reveal his true name or even whereabouts, he blogs his opinions, and humour and rants irregularly. Stubbornly he clings to his beliefs, e.g. that Faith does not give answers, it only prevents you doing any goddamn questioning. You are as atheist as he is. When you understand why you don't believe in all the other gods, you will know why he does not believe in yours :-) Oh, and he also has a neat English Bulldog called 'Kosmo'.

Some of my bikes

My Crypto Pages

My Maths Pages

Thursday, August 24, 2017

3 Neat Eclipse Photos :-)

Over here in Germany we didn't get to see even a partial eclipse of the sun on the 21st. So I've been scanning many US blogs to see the best eclipse photos, here are three I particularly like :-

This first one overlaps seven shots of the eclipse from partial through total and back to partial again. I like the way that this overlapping assembly demonstrates that the plane of the orbit of the moon around the earth is tilted about 5° off the plane of the orbit of the earth around the sun. If it weren't, we'd get a solar eclipse every month. The tilt makes them rarer.

This second photo is of totality. I've enhanced it with 3 green rings around solar protuberances which are looped back by the sun's magnetic field.

In this third shot, the photographer thought through ahead of time to work out where he would have to stand - and when - to get the shot. Well, actually six shots. They show the transit of the ISS space station across the disc of the sun during a partial phase of the eclipse. The other irregular dark spots are sunspots afaik. Well thought out, whoever you are! You got a spectacular photo :-)

Which do you like best?

Comments (1)
Cop Car wrote " I like the NASA photo mosaic showing the transit of ISS. NASA does fine work and credits: "Photo Credit: NASA/Joel Kowsky". "This composite image, made from seven frames, shows the International Space Station, with a crew of six onboard, as it transits the Sun at roughly five miles per second during a partial solar eclipse, Monday, Aug. 21, 2017 near Banner, Wyoming." Pergelator picked up the ball and ran with it; he has videos on his blog.

Monday, August 21, 2017

The Great American Darkness

Today a total solar eclipse crosses the USA, casting even less light upon the Great American Darkness. Expect chaos, not just during the eclipse :-(

Comments (1)
Ed (USA) writes "Too good to skip . . . Sun never went out when Obama was POTUS - just sayin' " Heh,heh, good one. Did you see that DT watched without glasses?

Saturday, August 19, 2017

Rare SG41 crypto-machine found!

Hikers, walking through the Bavarian forests near Munich, recently found a WW2 era SG41 crypto-machine which they took to be an old typewriter and turned it over to a Munich museum. Shame! Crypto geeks like yours-truly would have paid good money for that, it's very collectable.

Only 1000 were built, afaik. It was designed by the famous WW2 German cryptographer Fritz Menzer, who broke Hagelin's C36 rotor machine in 1936 and showed how to cryptanalyze their own Enigma. So the German military could have known not to use the Enigma and replaced it with something better (like the SG41), but, basically, they ignored him at the time.

In 1941/42 he designed the SG41 shown above, also referred to as the Hitlermuehle (Hitler's mill), which first went into production in 1944. About 1000 were built, most were destroyed by troops who realised they were losing the war. So they are pretty rare now. It uses the basic Hagelin design but improves it by having six mutually prime pinwheels and , most importantly, variable stepping. The key-space was at least 15,000 times larger than that of the Enigma which the SG41 was intended to replace. Bletchley Park did not, afaik, break it, although it seems to me to be susceptible to hill-climbing techniques (maybe that's how the hikers found it ;-)

In his various attempts to improve Enigma, which he knew to be crackable, Menzer also invented the hole-filling roller (1943) which would enable a standard Enigma to have variable stepping (but needed the users to make 2 more steps); key-device 39 (in 1939) which generated paper tapes (as the SG41 did); the key-case cipher box; the key-disc lock-washer designed for use by spies; and the key-wheel, an early stream cypher. All these were purely mechanical devices, like the M-209 the Americans used. The M-209 was a lug and pin design by Hagelin, an improved C-36, without a keyboard. Afaik, Hagelin never received royalties for it :-(

Tuesday, August 15, 2017

Hollywood Humour

Just passing on some Hollywood Humour recently passed to me, concerning new movies to be released soon :-

An instructional documentary about premature ejaculation : Coming Soon ;-)

Russel Crowe starring as a cannibal who was very happy that he ate both his wife AND his mother-in law : Glad he ate her too ;-)

Vin Diesel starring as a man angry about his premature ejaculation : The fast and the furious ;-)

And eternal pirate Johnny Depp, whose ship Black Pearl was sunk several times, points out to Donald Trump that the ship of state is the only one that leaks from the top ;-)

Friday, August 11, 2017


On monday evening, we had a partial eclipse of the moon over here. Sadly the sky was overcast here, so I've had to borrow this photo from a press site. These partial lunar eclipses are fairly common, but always nice to watch.

Several years ago, there was a total eclipse of the sun ( a rare event) here in Europe and so the wife and I drove the couple of hundred miles into the Elsass hills which were on the path of totality. Up on the hillside so we could watch the edge of the totality shadow come racing silently along the valley below at about Mach 3 (imagine a SR71 Blackbird at sea level). First time I've had an impression of how fast Mach 3 really is :-)

Some spectators there hadn't thought the eclipse thing through however. They wore T-shirts and were surprised when it got really cold even in the penumbral shadow and after totality even started to rain (the temperature had dropped below the dew-point). Don't say I didn't warn you!

Now the USA is getting a total eclipse of the sun (once a century) this month.

The path of totality crosses the whole of the continental US. A hundred million people or so live within a day's drive of the path of totality, so I recommend my US readers take that drive (as we did years ago), it will be the only opportunity in your lifetimes. Some car rental companies (e.g. Hertz) have overbooked already and are cancelling reservations (is that legal?):-(

Dress warmly in something waterproof. Get yourselves proper eye protection, enough for everybody so you don't have to share. Do NOT look at the sun directly lest you blind yourselves. We used a filter for the hydrogen-alpha spectral line and thus had the added benefit of seeing protuberences at the edge of the sun's disc. The corona was surprisingly large too, considering the sun is 93 million miles away!

NASA will be blogging it live of course, but if you get some good photos of the totality, be sure to blog them yourselves : expect to see this :-)

CC, you are almost on the line of totality at 13:08 on 8-21-2017, so just drive to northern KC, take a few photos and blog them for us please :-)

Comments (6)
Barbara (UK) asks "We are watching the Perseids right now (12th 11pm), how about you?" Sadly no shooting stars for us, 100% cloud cover here :-(
Hattie (Hawaii) wrote " We were planning to go to Eastern Oregon for the eclipse, but I can't travel now. Thanks for the tip about NASA's coverage. Better than nothing!" NASA will avoid any local cloud-cover problems.
John (UK) asks "Any other rare events seen? Yes, I've twice been present during volcano outbreaks, once in the Canary islands and the other in Iceland. Also we had good viewing of the transit of Venus in 2012 (on my birthday, too :-)
John writes "You'll never see a transit of Venus again, but there'll be a transit of Mercury on 11/11/2019 afternoon." If we live to see it ;-)
Cop Car wrote " Unfortunately, I won't be able to travel for the eclipse. The Red Cross has a bunch of us on standby for duty in the time surrounding the eclipse. (They aren't sure what, if anything, will actually take place in the way of civil happenings!) It'll be easy enough for me to punch a hole(s) in a piece of cardboard to view/photograph the [projections of the] shadows. As I recall, in about 1962 (had to have been after June 1960 and before June 1963), we did the pin-hole-thing with the kids for a partial eclipse that was visible from Derby. I, personally, plan to depend upon NASA to get good footage of the total eclipse. If I get anything from our local astronomers, I'll share it. Nice posting on eclipses, btw." Folks, you don't look through the pinhole. You let the sun shine through a pinhole on a piece of card projecting an image of the eclipse onto a second piece of white card (which you may photograph (without a flash). Just making it absolutely clear what Cop Car means :-)
Marie (F) writes "Not true. Total eclipses of the sun are NOT rare, they happen about every two and a half years, just not where you can see them easily!" Okay.

Sunday, August 6, 2017

Thin Man Fail

This being Atom-Bomb week (Hiroshima 1945 on the 6th and Nagasaki 1945 on the 9th), I thought I'd blog a bit of early nuclear history.

The Nagasaki bomb (August 9th 1945), called Fat Man, was an implosive design : a hollow sphere of fissile material had an outer shell of high-explosives. The segments of the outer shell were carefully timed to explode all at once, driving the fissile material (plutonium-239) into the centre where it achieved critical mass, exploding with 21 kilotons yield.

The Hiroshima bomb (August 6th 1945), called Little Boy, was a gun-barrel design : a "bullet" of fissile material was fired along a barrel into a sub-critical mass of the same fissile material (uranium-235) where it achieved critical mass, exploding with 15 kilotons yield.

Both designs need put the critical mass together very quickly to avoid a "fizzle" where the fissile material melts before contact. This was a problem for the first A-bomb design, the Thin Man.

The Thin Man gun-barrel needed a muzzle velocity of 3000 fps, in order to put the critical mass of plutonium together quickly enough, which was close to the maximum achievable in 1944. This meant that the gun-barrel would need to be 17 feet long! There was only one aircraft in the Allied inventory that could carry a Thin Man unmodified: the British Avro Lancaster. Unneccessary US patriotism however, demanded the use of a Boeing B-29 Superfortress which had to be modified to carry a Thin Man by removing part of the main wing spar(sic!) and the oxygen tanks located between the B-29's two bomb bays.

Not only this, but there were problems suspending the 8 ton bomb in the B-29 bomb bay. In several tests with dummy cases, the bomb pre-released before the bomb-doors opened, and the cases proved to be aerodynamically instable anyway. Furthermore, the spontaneous fission rate of their nuclear-reactor-bred plutonium was too high, meaning the A-bomb could have pre-detonated/fizzled too!

So the Thin Man effort was scrapped but the design was used for the Little Boy which used uranium-235 instead as a fissile material and so the gun-barrel only needed to be 9 feet long, fitting better into a B-29. The casing was aerodynamically stable too and weighed only 4.5 tons, putting less strain on the release mechanism.

Urban legend has it that Fat Man was named after Churchill and Thin Man after Roosevelt. Wikipedia provides a less glamourous naming though :-(

Comments (2)
Anon (D) asks "How many were made?" Thin Man zero, as explained above. Little Boy : six, or 10 or 25 depending on which source you believe. Fat Man : 120 (up to 1950). The subsequent design, the Mark 4, had a production run of 550; the Mark 6 numbered 1100.
Cop Car wrote " If you've not already seen it, I'll point out a novel that conjectures upon nuclear weapons' having been developed rapidly enough for use on Germany in 1944. Title: Berlin Project / Benford, Gregory Identifiers: LLCN 2016040114 (print) ISBN 9781481487641 (hardcover: acid-free paper) ISBN 9781481487665 (ebook) Of course, the points that you made in "Thin Man Fail" are made in the book - such as - the Lancaster being the only aircraft capable of delivery. I'm about ½-way through." Thanks for the ISBN, I must order it :-)

Recent Writings
3 Neat Eclipse Photos :-)
Great American Darkness
Rare SG41 found!
Hollywood Humour
Thin Man Fail
Visit to Venice
Lake Garda Mountains
LBGT marriages legal
Stagger McFly
Aircraft Museum
ecce libri : Hobbitus ille
The HP warehouse
Bode River scenery :-)
On turning 73
Time to die :-(
Learning to fly...
In Memoriam : Klacks
Pynchon turned 80
Oldtimer Meet in Boke
May Day ;-)

Ain Bulldog Blog
Balloon Juice
Cop Car
Earth-Bound Misfit
Fail Blog
Finding life hard?
Hattie (Hawaii)
Mostly Cajun
Not Always Right
Observing Hermann
Rants from t'Rookery
Yellowdog Grannie

Archive 2017:
Jan Feb Mar Apr
May Jun Jul
Archive 2016:
Jan Feb Mar Apr
May Jun Jul Aug
Sep Oct Nov Dec
Archive 2015:
Jan Feb Mar Apr
May Jun Jul Aug
Sep Oct Nov Dec
Archive 2014:
Jan Feb Mar Apr
May Jun Jul Aug
Sep Oct Nov Dec
This blog is getting really unmanagable, so I've taken the first 12 years' archives offline. My blog, my random decision. Tough shit; YOLO.
Link Disclaimer
ENGLISH : I am not responsible for the contents or form of any external page to which this website links. I specifically do not adopt their content, nor do I make it mine.
DEUTSCH : Für alle Seiten, die auf dieser Website verlinkt sind, möchte ich betonen, dass ich keinerlei Einfluss auf deren Gestaltung und Inhalte habe. Deshalb distanziere ich mich ausdrücklich von allen Inhalten aller gelinkten Seiten und mache mir ihren Inhalt nicht zu eigen.

This Blog's Status is
Blog Dewey Decimal Classification : 153
FWIW, 153 is a triangular number, meaning that you can arrange 153 items into an equilateral triangle (with 17 items on a side). It is also one of the six known truncated triangular numbers, because 1 and 15 are triangular numbers as well. It is a hexagonal number, meaning that you can distribute 153 points evenly at the corners and along the sides of a hexagon. It is the smallest 3-narcissistic number. This means it’s the sum of the cubes of its digits. It is the sum of the first five positive factorials. Yup, this is a 153-type blog. QED ;-)
Books I have written

Index/Home Impressum Sitemap Search site/www