Eunoia
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> Most recent Blog Comments Policy DSGVO Impressum Maths trivia Search this site RSS Feed Eunoia, who is a grumpy, overeducated, facetious, multilingual naturalised German, blatantly opinionated, old (1944vintage), amateur cryptologist, computer consultant, atheist, flying instructor, bulldoglover, Porschedriver, textbookwriter 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 after the death of his old bulldog, Kosmo, he also has a new bulldog, Clara, since September 2018 :)
Some of my bikes
My Crypto Pages

Friday, June 28, 2024
A very amusing bookHere is yet another book I can thoroughly recommend. It was given to me as an 80th birthday present by friend Lothar, to whom many thanks. The author is Randall Munroe, probably better known in the internet as cartoonist "xkcd", so the illustrations are in his stickfigure style. I already own three of his previous books, What If ?, How To and Thing Explainer all geeky. This one gives serious scientific answers to the most absurd questions. The ISBN is 9781473680623. Hardback with about 350 pages. Do go get a copy and you will enjoy reading it, as I did. Tuesday, June 25, 2024
Pythagoras on a SphereBack in the old days of ancient Greece many people thought the Earth was flat (been reading too many Discworld^{®} novels probably). And so we got Euclidean geometry on a plane. Indeed, Pythagoras proved that A^{2} + B^{2} = C^{2} for rightangled triangles only on planes; something we all learned in school. Here's my proof of Pythagoras' theorem :) Now imagine if Pythagoras had known that the Earth is a ball, not a plane. What would his theorem look like for a spherical right triangle? Certainly not A^{2} + B^{2} = C^{2} ! First off, we need to define what we mean by a spherical triangle. A great circle on a sphere is any circle whose centre coincides with the centre of the sphere. Arcs of great circles are the shortest distance between two points on the surface. Long distance aircraft thus fly along arcs of great circles (ignoring the effects of winds), and ships sail along them too. There are four great circles in the sketch shown below.
A spherical triangle is any 3sided region enclosed by sides that are arcs of great circles. If one corner angle is a right angle, the triangle is a spherical right triangle. In a spherical right triangle, let C be the length of the side opposite the right angle (the hypoteneuse).
Let A and B be the lengths of the other two sides.
Let R denote the radius of the sphere (or Earth on our case).
Then Pythagoras' Theorem on a sphere tells us that
cosine(C/R) = cosine(A/R) * cosine(B/R). Now I won't bore you nonmathsgeeks with my proof thereof and
the mathsgeeks can surely derive it themselves. Please note that as R goes to infinity the world gets flat and this equation
devolves back to So when someone asks you about Pythagoras' theorem, just tell them cosine(C/R) = cosine(A/R) * cosine(B/R), after all, A^{2} + B^{2} = C^{2} is just a special case ;)
PS: I originally showed you this in 2009, so I am just repeating myself. Fryday, June 21
Dracarys!R ecently Chuckhas been writing about House of the Dragon and he has a theory,"I prefer to think the dragon legends come down to us from a previous civilization that had mechanized, flying war machines like the A10 Warthog. After that civilization collapsed and the art of heavierthanair aircraft was lost, how would you explain something like an A10 to your kids? "There were fire breathing monsters that flew through the air and destroyed everything in their path". That's how." Later, he did a post detailing how (wing area vs. mass) dragons flew etc, do go read it please. But I decided to follow up on the Warthog idea, as follows. The A10 Warthog is a plane carrying a really big Gatling gun. Or it is a really big Gatling gun which happens to be carried by an airplane, in the nose. The Warthog will do a lowaltitude strafing run at 300 Knots and, if it were to use all of its ammunition at once, would use it all up in just 17 seconds. Here is the maths I did. The plane flies at about 300 knots usually (roughly 156 m/sec) and weighs some 19 tons. The magazine can hold 1350 rounds, each weighing about a pound, of which the bullet weighs lets say 200 grams (guessing, in the absence of me knowing the facts). Muzzle velocity is Mach 3 = 1000 m/sec. So 1350 * 0.2 * 1000 = 270,000 kgm/s of bullets' momentum, divided by those 19 airplane tons implies 14.3 m/sec = about 28 knots of deceleration for firing all that ammo; more when the bigger magazines were later introduced. So 30028 = 272 knots speed at the end of this example Dracarys run. After the strafing run, the Warthog pulls up sharply to get out of enemy ground fire. But just how sharply? Well stall speed for a Warthog in level flight is given as 120 knots, but stall speed increases with the square of the Gloading of the pullup. Now 272/120 = 2.27 and 2.27^{2}= 5.1529, so let us say a 5G pullup would stall the plane. Even I could pull 5G when doing aerobatics in the Pitts biplane, but fighter jocks with the Gsuits (inflatable trousers) regularly can pull 9 G, so would have to be careful not to stall the Warthog. BTW, 17 seconds of firing at an average of 286 knots implies the target is a tank/vehicle column about 2.5 km long and straight, unlikely even for Russian tanks (do they have that many left?). So this is an unlikely scenario. And do you know why the Mother of Dragons uses the command Dracarys? Because Supermarine had already taken the English translation "Spit Fire!" ;) And why Mother of Dragons? Well, Lockheed had already used the name Dragon Lady for their U2 spyplane ;)
Comments (4) Sunday, June 16
A short history of photographyThe oldest photo Wikipedia knows about is from 1826, a French photo of a view from an upstairs window, using bitumen as the medium. Pinhole camera, exposure time was about 9 hours. In 1837 a pinhole camera took the first photo made in Germany; the photo is of the Frauenkirche (Our Lady`s church) in Munich, taken in March of 1837; exposure time was several hours. Sepia. 1860 saw the first aerial photo taken from a tethered balloon over Boston, Mass. 1861 : First colour photo. Tartan Ribbon, taken by no less a person than famous physicist James Clerk Maxwell in 1861, based on his 1855 research. 1882, showing Navajo youth Tom Torlino as he started the Carlisle Indian Industrial School (USA) and 3 years later, first Indian graduate there afaik. Another Black and White (sic!) photo. George Mclaurin, first black man to be admitted to the University of Oklahoma. It was 1948 and US was still segregated, so he had to sit separated from the white students. 1978 saw the start of Microsoft, who bought 86DOS 1.10, renamed it MSDOS. Our most recent photo, SWMBO and I on my 80th birthday; photo by Andreas.
Comments (2) Friday, June 14
That pale blue scytheWhile I was AFK over the past few weeks the scythe of the grim reaper took Hilde (Prof. Dr. phil), she was just 6 months older than I am and it also took Johannes (67); his ashes were scattered from an ultralight flying over Lake Geneva in Switzerland, a true pilot's burial. RIP both.Comments (1) Jenny (Ibiza) said "What makes you think the scythe is pale blue?" Novels by Terry Pratchett. Monday, June 10
Biker Birthday BashS aturday afternoon our street was permeated by the sound of rolling thunder as a dozen biker friends (un)surprisingly came to celebrate my 80th birthday. Luckily we had good weather and so could use the back garden. Here are some of my photos.L2R: Matthias, Andreas, Dieter, the other Matthias. On the left: Peter and Rüdiger Frank with Marion L2R: All in profile, Thomas, Marion, Dirk, HansJürgen Marion, Matthias, Dieter, HansJürgen, Dirk, Volker, Thomas listen as ... ..... Matthias reads his selfwritten Laudatio poem. And I just bask in the sunshine as his Laudatio is read. After all had gone, SWMBO relaxes in the hammock.
Comments (1) Saturday, June 8
OctogenarianTurned 80 today. Hurrah! Having been ill recently, I didn't think I was going to make it. Subdued party tomorrow, so photos to follow. Comments(12) Peter Harris (UK) wrote "Happy Birthday, Octoman!" Thanks. Dirk R. (B) whom shares with me an obsession with cryptography, wrote " Happy birthday… although, that’s historically and mathematically, long time ago, in some maternity ward. Still an odd phrase/expression. I whish you many more years alive and kicking, but since your still young, you have at least 20 years ahead before becoming adult ;]..... ....this on one big KL7 page (fortunately with a menu). See One big KL7 page . Hoooooowever, If you prefer to polish your motorcycle, no problem." Sold my motorcycle, due to my arthrose. Now have a Porsche 944 Oldtimer. A couple of dozen bikers turned up (un)surprisingly for a beer etc and several people called on the phone. Photos of the bikers tomorrow. Billions of Versions... wrote " Happy belated birthday. I'm about 2 1/2 years behind you. " Thanks Mike. Marie (A) sent this piccy she found on the web of other octogenarians : Bruce wrote "80? So you've caught up with Keith Richards. I'll catch up with you in September, but tS06:43:16 AM then Keith jumps ahead in December. For me saying 80 is a shock. A little pride that I'm that bad because the good die young. A little sad because it's a clear signal to the ladies that I'm out of the running. So happy belated birthday and wishing you many reruns." Thanks, stranger. Comrade Misfit wrote " Belatedly, happy birthday Stu." thanks, Stinson Gal! Fly safe! Link to the previous month's blog. 
Recent Writings A very amusing book Pythagoras on a sphere Dracarys! A history of photography That pale blue scythe Biker Birthday Bash Octogenarian Friend Hubert turns 60 Slaughtering the pig ;) Pentecostal Post Lufthansa routes 1937 Aurora Quax Hangar open day Titanic humour :( Walpurgisnacht Subtle Stupidity Plaques SWMBO turns 79 Speed Trap Week KTM Open Day The Judas Pyre Blogroll Ain Bulldog Blog All hat no cattle Balloon Juice Billions of Versions... Cop Car EarthBound Misfit Fail Blog Finding life hard? Hackwhackers Infidel753 Mockpaperscissors Mostly Cajun Not Always Right Observing Hermann Pergelator Starts with a Bang Yellow Dog Grannie Archive 2024: Jan Feb Mar Apr May Jun Archive 2023: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2022: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2021: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2020: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2019: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2018: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Archive 2017: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 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 3narcissistic 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 153type blog. QED ;) Books I've written

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