James' World

Nice article on what’s new in DNS in the past 2 years – not much apparently, according to Cricket Liu and ThousandEyes.

dnsdist

When deploying a production change, usually you have a rollback procedure – documented even! 🙂

But sometimes after a deploy, things don’t work exactly as expected. At that time, you need to decide which is better: rollback, or fail forward?

If it’s a small, isolated code change and you can operate with the old version, often it’s an easy decision to rollback.

But in more complex situations, sometimes it’s better to accept that the change wasn’t perfect, but:

• is still an improvement overall, and gets you closer to your goal
• or is equivalently bad to the previous situation, but in the right direction
• moves to a new target architecture that can’t be simulated in qa or stage for reasons of time, cost or complexity.
• serves as a commonly-understood stake in the ground, or anchor point. “Now that we’re here, we can see the right direction!”

and keep the change and fail forward instead of doing a rollback.

Generally to know if failing forward is an option, you need:

• enough personal and organizational responsibility to accept the risks and handle the consequences.
• a clear understanding of the overall IT systems and IT risks
• a clear understanding of the overall business systems and business risks
• availability of staff to do verification and fix small issues that arise
• to pick a good time for the change that minimizes stress and risk
• Monitoring and application logging tools help evaluate the situation. (I’d even suggest rounding out your tools inventory beforehand if failing forward is new to you.)
• communicate that you may fail forward if necessary, based on calculated, not reckless, risk assessment and that rollback is still an option.

Some actual examples of when I have failed forward successfully:

• firewall rule changes that were closer to the final goal, but broke a couple of servers temporarily.
• database schema changes that were correct, but required a day or two of minor internal application updates that were not in the original QA test plan.

Some actual examples of when fail forward was not acceptable, and rollback was required:

• changes from httpd 2.0 to 2.4 that actually required significant re-QA and updates to the deploy process
• database schema changes that were correct, but required a major application re-build and re-QA totalling more than 3 hours of downtime
• changes that affected legacy applications with no budget for developers or QA.

Especially with databases, the arrow of time cannot be reversed. So database restores results in the loss of data on busy systems, making fail forward the default policy at many SaaS companies. Additionally, failing forward helps with development velocity.

I recently created a new minimal build system, called pico-build, that is hosted on github.

pico-build is the world’s smallest, yet featureful, three-environment (dev, stage and prod) build and deploy system.

It uses make, but in a different way than normal – pico-build manages entire environments, not individual files.

$ make
usage: make [help|check|dev|stage|prod|dist|all]

It is intended for individual programmers and small teams who want to test and deploy to three environments, but don’t want to spend time setting up (and patching) Jenkins or building a CI/CD pipeline.

Folder structure of a website deployed with pico-build, showing the deploy flow in red

When I was working in Toronto in the mid-90’s, I was offered a game developer role at a downtown company.

At the time, I was one of the top arcade players on Centipede, Millipede, Battlezone and G-LOC. I had also written clones of Centipede for the PC in C and assembler.

They offered me exactly half the salary of another offer, and expected developers to sit shoulder-to-shoulder around wooden picnic tables. They oozed sketchiness, and I already knew how to write a game, so I passed. But hey, they had a blue screen room! 🙂

I moved into Internet Operations, ending up at Netscape. Eventually I did some consulting for a slot machine product which needed to pass Las Vegas gaming compliance. Small world! 🙂

To pass, one of the requirements was that the game had to be guaranteed to start in a known state each time, presumably in case employees or bettors tried to improve their odds by yanking the power and restarting the game.

That guarantee was accomplished by using a journalling filesystem and a built-in UPS with linux services carefully configured to start and stop reliably.

Some links showing how tough the game industry is in 2018:

The tragic end of Telltale Games
infinitroid.com: Did I just waste 3 years?
playstationlifestyle.net: More Than 1,000 Jobs Were Lost in the Games Industry Over the Past Year, 10 Studios Closed Doors

PSA: If you host domains with Godaddy, and you’re a day or two late in renewing a domain, it will be “parked” – in other words, assigned a different IP address than the previous one.

This is as bad as it sounds, since your site availability and SEO rank will be hurt as various crawlers will cache the random parking pages for varying periods of time, which can last for weeks.

To remove domain parking so that Internet users can see your site again:

1. login to your Godaddy account
2. pay for your domain renewal if still possible
3. find your domain and click on the DNS button
4. look for the parking widget form in the bottom right and click on the trash can to disable parking
5. next to your A record, the status “Parking” should disappear and the pencil icon should re-appear so you can edit it to the correct IP address again
6. do nothing at first for 60 minutes to avoid negative DNS caching. Then try your site, monitor Google search, etc.
7. for future reference, print out your DNS zone settings once it is working.
8. add application monitoring to your site to detect IP and content changes.

Otherwise, contact Godaddy support ASAP.

If you need quick temporary access for intranet/personal use, just add a hosts entry pointing to the domains and sudbdomains you need and restart your browser. Your site will work perfectly, but just for you.

Interesting Letter to Airmen about pilots taking shortcuts on Standard Instrument Departures (SIDs) at Van Nuys Airport (VNY.)

In the particular example supplied by the FAA, pilots are doing an early NW departure turn instead of SW and waiting for vectors, which in this case doesn’t look too bad from a terrain standpoint, but:

1. VNY is in a valley sandwiched by airports on 3 sides (Burbank, Santa Monica and LAX) plus it’s under the LAX veil.
2. the local airport area topography for the example turn (see below) looks flat on terrain maps, but cranes do get parked near airports and weather obscures those surrounding hills.
3. own navigation causes flow and communication surprises for ATC. The vector instruction may just exist to add time for the hand-off from Tower to Approach (as well as allow airport overflights to Burbank.) Reaching IPIHO before talking to Approach would get ugly.

On the other hand, we’re talking about a very compact area (4 NM x 2.2 NM according to DME) and ATC likely vectors pilots according to the shortcut anyway. Please leave a comment if you know what the real issue here is.

globalair.com: CANOGA TWO DEPARTURE
ainonline.com:VNY Pilots Turning Too Early on SIDs
faasafety.gov: Pilot deviations – Van Nuys Airport (VNY) – Standard Instrument Departure (SID) Procedures
faasafety.gov: Pilot deviations associated with Van Nuys Airport (VNY) Standard Instrument Departure (SID) procedures

As a commercially-rated airplane pilot who’s read over 2,000 accident reports, I followed the Southwest Flight 1380 fatal uncontained engine explosion closely.

Executive Summary:

The FAA is likely investigating the following concerns:

1. how well did the pilots handle the emergency (it appears well, handling the depressurization event and descending to a breathable altitude.)
2. engine turbine blade failure (engine design and maintenance)
3. uncontained engine shrapnel (engine design)
4. uncontained engine shrapnel into passenger cabin, resulting in the death of a passenger and 7 with minor injuries (plus psychological trauma, esp. to first responders) (fuselage design)
5. improper use of oxygen masks by most passengers (passenger safety briefing, oxygen mask design.)
6. the passenger killed was wearing a seatbelt, yet was partially blown out of the airplane. Was the seat belt worn snugly. If so, do we need 3-point or 5-point harnesses?
7. it’s the first US airline accident in 9 years, and the first en route fatal accident for Southwest. The FAA wants zero accidents for political reasons, and Southwest wants zero accidents as an operating airline.

The oxygen masks descended, but passengers wore the mask over their mouth. Masks are intended to be worn over the nose, so likely the mask shape will be changed and training materials updated.

There are FAA regulatory and political expectations that uncontained engine failures don’t happen. However the physics of large machines with rotating components says otherwise. Likely this will result in armoring the engine shroud and hull with kevlar or metal, and further engine design changes based on energy of rotating components.

There are FAA expectations that the aviation industry mitigates risk so that the uninformed flying public is not injured. However, a passenger died en route.

After the depressurization, oxygen masks were expected to descend and be used by passengers over their nose. Instead they were put over their mouth. Likely passenger briefings will become more detailed, and oxygen masks will be changed from a round to pear-shaped.

Fortunately the pilots descended relatively quickly, at 3,000 fpm, to 10,000′, as:

1. time of useful consciousness at 35,000′ is only about 1 minute
2. the masks were worn incorrectly
3. only about 10 minutes of oxygen is available in cannisters when properly provisioned

However, was the emergency descent actually fast enough? With an improperly-worn mask, generally-speaking the body needs sufficient cabin oxygen pressure within 4 minutes to prevent brain-damage or death.

avweb.com: Southwest Accident Brings Passenger Safety Briefings To The Forefront
philg: Southwest 1380: think about the flight attendants
avweb.com: Southwest 1380: “Flew Like a Rock”
ainonline.com: Southwest Airlines 1380 Engine Failure 4/17/2018 ATC Audio
1 killed as Southwest jet makes emergency landing after apparently blowing an engine in flight

Qantas Oxygen Mishaps (2007 and 2008)

These Qantas incidents illustrate the importance of vigilance when maintaining passenger oxygen canisters:

1) Careless filling with nitrogen instead of oxygen:

theage.com.au: Probe after Qantas pumps wrong gas into jets PPRuNe

2) Oxygen canister valve failure due to unknown cause:

nytimes.com: Officials Ask Qantas to Inspect Oxygen Canisters
telegraph.co.uk: Exploding oxygen bottle caused hole in Qantas jet
smh.com.au: Valve in oxygen cylinder the culprit in 747 explosion

Oxygen canister valve failure causes depressurization in Qantas 747 (2008)

I spent the afternoon at the amazing Hiller Aviation Museum at San Carlos Airport (SQL).

The museum is a real gem, with compact (3 hours to see everything) but nice exhibits in the areas of:

1) Hiller helicopters
2) flying platforms
3) engines from 30 HP (Wright B) to 3,500 HP (Wasp), including a Merlin
4) flight simulators
5) 727 and 747 “steam gauge” cockpits
6) a truly beautiful Grumman Albatross
7) models of most other aircraft

(The Boeing SST that was on loan has been returned to Boeing.)

Flight Simulators at Hiller

Hiller has done a great job of integrating modern computer displays and flight simulators into their exhibits:

Mechanical Flight Simulators

– Curtiss P-2 with map table
– portable flight director
– IFR simulator
– Stearman simulator

Computer Flight Simulators

– 16x PC on 2nd floor (FS9 with Saitek yoke, engine quadrant, and pedals with 3 monitors)
– 1x Redbird FMX full-motion AATD
– Google Earth “wall”
– Wright Flyer (MS FS9 with wood levers and 3 screens)
– a real helicopter with cyclic control and 1 screen

They are moving to X-Plane 11 as PC hardware compatibility leaves FS9 behind.

1) The 747-100 fuselage static display behind the museum lets you climb up the 1st class cabin and sit in the cockpit. It has 5 seats (pilot, copilot, navigator, radio and FAA.) It is closed at 4:30 pm.
2) Behind the 747-100 is a small platform where you can observe takeoffs and landings. It is closed at 4:30 pm.
3) The Burger King next door has a helicopter on static display outside, and historical aviation fotos and a “briefing area.”

avweb.com: Personal Flight Simulators: one-G Simulation

Congrats to SpaceX on the successful launch of Falcon Heavy, with a Tesla for ballast.

And yes, recovering two boosters simultaneously on adjacent pads is showing off, but of the best kind!

One of the main goals of this launch was to not blow up the launch pad, since that would:

1. halve the number of pads available
2. take a year to rebuild
3. and cost about $50 million.

Although it’s always uplifting to see a successful launch, it’s actually valuable to have failures early-on. Having a successful first launch means the rocket was likely over-engineered (ie. heavy.) Hopefully review of the sensor data can find something worth investigating and fixing before launching satellites or people.

One launch doesn’t mean the mechanical and acoustical vibrations between the 27 engines is dampened enough, or even understood at this point.

“In America, if you have lots of money, you can build a space program and launch your own car into heliocentric orbit.” 🙂

SpaceX launches Falcon Heavy, the world’s most powerful rocket
WATCH LIVE: SpaceX to Launch Falcon Heavy Rocket #MarsRocket @3:45pm EST delayed

I watched Superbowl 52 on restaurant cable. Great seat for a great game with the the most ground and air yardage in history.

PHI won 41 – 33 NE in Minneapolis with some nice trick plays in the end-zone.

Brady started the game with an injured hand and had to bench for a while.

Sadly Brandon Cooks didn’t see a legal but huge hit coming after a reception and ran into a player with helmet contact, resulting in a head injury.

The kickers said they “had problems with the in-turf logos.” There were a few missed field goals, including one that hit the post.

Justin Timberlake did the half-time show, but with only 15 minutes to perform his appearance was too brief.

Nick Foles, High-Powered Eagles Stun Tom Brady, Patriots to Win Super Bowl 52

Jack in the Box (Jack and Martha Stewart) and Amazon (Alexa “turks”) had some funny commercials.

time.com: These Are the Best 2018 Super Bowl Commercials

The last 747 has been retired from passenger service in the USA.

I’ll miss the 747 because it was the only widely-used airliner built for trans-oceanic flights:

1. For safety reasons, I’d rather have 4 engines than 2 for trans-oceanic flights. The slow acceptance of twin-engined airliners under ETOPS over the past few decades means greater fuel efficiency for airlines, but in a pinch you’re left with one engine, which is not a good situation for passengers.
2. The 777’s that I’ve flown on to Asia don’t have eyeball air vents, so I end up roasting on long flights.

Delta Retires Last USA 747 to Boneyard

Malaysia hunts owners of Three Boeing 747s abandoned at airport

Macbook Pro 2009/2010 notebooks came pre-installed with Snow Leopard (10.6) Mac OS X.

As of Dec. 2017, very little popular software will work or update on anything older than Mavericks (10.9):

• Several popular chat programs no longer work – Skype app, GotoMeeting, Google Hangouts, Highfive
• No major browsers are supported
• Even Apple updates require 10.8 or higher – for now.

Before you update Mac OS X, note that many users have complained of post-update issues including:

• failure to boot and very slow operation on hard disks. It is possible to downgrade later, but there’s no guarantee that your data will be ok. So backup your files first!
• new, empty keychain folder. Delete it and reboot. (You probably will have to re-enter all of your wifi, browser and application passwords.)
• Xcode will have to be upgraded. Virtualbox will have to be upgraded to open previous VMs, and if you use Dia, read this to fix it
• if your Mac was not purchased in your name, apps like iMovie will not be updatable from the App Store. (iPhoto 2011 will not work at all on High Sierra since it has been deprecated. Your photos will be migrated into the iCloud and accessed with the new Apple Photos app.)
• Restart and Shutdown takes a long time or hangs. If I need to restart with High Sierra, I close the apps manually and hold the power button for 6 seconds to force a power off.
• Resume (open lid to resume) is flaky. Always slow to resume, sometimes restarts.

The best way to update Mac OSX is to use the Apple softwareupdate command line interface (CLI) tool:

1. Confirm you have 2 GB RAM and at least 8 GB free disk space
2. plug your charger in and connect to a reliable WiFi hotspot, or find a tutorial on creating a USB update media
3. Close all open applications, including Textedit.app files
4. Backup your files and all passwords! If the in-place update fails, you may have to wipe OS X and do a fresh install, and the install will likely bork your keychain file.
5. open Terminal.app and run these commands to find out what updates are available, and then apply the updates:
   1. sudo softwareupdate -l (copy and paste the updates list to a file and save it for later reference)
   2. sudo softwareupdate -ia

$ sudo softwareupdate -l
Password:
Software Update Tool

Finding available software
Software Update found the following new or updated software:
   * macOS High Sierra 10.13.2 Supplemental Update- 
	macOS High Sierra 10.13.2 Supplemental Update ( ), 138293K [recommended] [restart]

Otherwise you need to register with the App Store using a credit card to use Software Update. Expect 10 or more reboots/logins and about 4 hours total time if everything goes smoothly. The final reboot will actually install the new software – it will take about 41 minutes on a hard drive, or 20 minutes on an SSD.

Tips

• if you want to keep all your windows open as long as possible, use “Apple … Restart” instead of the installer restart button until the installer says “Ready to Install”
• Command+L on the installer dialog window will show the installer log.

Troubleshooting

• If the install window closes and you want to retry running the installer, open the Applications folder in Finder and click on “Install macOS High Sierra”.
• After the installer is downloaded you will not be able to see the update label name in sudo softwareupdate -l
• An error dialog saying “The recovery server cannot be contacted.” means a network connection error or clock setting error that causes SSL certificate problems
• if the machine becomes not bootable, power cycle while holding Command+R to restore the old OS X and try again while following a recovery tutorial on another machine.

apple.com: High Sierra macOS freezing and stops, HN
W: Macintosh operating systems

PSA for Mac OS X users on older machines like Lion and Mountain Lion: if you’re stuck on Skype 6.15, and can’t do video chat after the Microsoft’s July 3, 2017 breaking update …

Apple Facetime is a free video chat application that comes with Mac OS X.

Some tips for using Facetime:

1. It seems to use an entire CPU core, and will quickly drain your battery, so plug in.
2. To add a new contact, you need to know their Apple ID email or their iPhone number. For phone numbers, use the full international prefix with 0 or 1, but without +.
3. By default if Facetime has a window visible (ie. it’s opened), it will enable the camera and consume power. To prevent that, click on the yellow dot to minimize it (ie. background it.)
4. To make Facetime wait for calls, minimize it (click on the yellow dot) or leave Contacts open.
5. If Facetime is not for you, try iMessage/Messages/iChat.
6. Facetime on iPhone is paused automatically when they switch apps and shows a “Paused” message. Facetime is not paused on Mac OS X.

HN Discussion

In the 90’s and 00’s, programmers used to scorn front-end designers who called writing HTML “programming.” That changed when CSS arrived and pixel-perfect results raised the bar.

Here’s some tips for programmers struggling with fixing CSS rendering problems:

Before Getting Started

1. Most programmers are not artists, so don’t write your own site-wide layout CSS. Either find a designer or use bootstrap or an alternative. If you’re doing more than minimal JavaScript programming (ie. using AJAX and/or modeless dialogs), use jquery or an alternative.
2. Treat a CSS project like learning a new programming language. Schedule a day when you’re fresh. You will need all of your concentration ability if you’re new to CSS because of the nested inheritance and browser quirks. If you finish early, that’s a nice bonus.

Getting Started

1. You may want to capture screenshots of what the original site looks like. The Mac OS X Preview app has professional-looking annotation features by Adobe under “Tools … Annotate.”
2. make a backup of the old CSS directory and save in a safe place. Then copy the CSS into a subdirectory so you can use the diff command on the old and new versions
3. if your site uses normalize.css, ensure it’s the most recent version, especially before mobile testing.
4. ensure your network environment has isolation: no load balancers, proxies or far future expires that can cache your old CSS files while testing
5. use the W3C HTML and CSS validators to get a feeling for what’s there and pair each div with /div (I helped debug the original HTML validator.) 🙂
6. use browser developer tools to examine the CSS. My favorite is Firefox’s Inspector.
7. remember the hierarchy with CSS:
   1. the most-specific style wins
   2. the last definition wins, whether at the block or file level
   3. id’s win over classes. (Use CSS classes whenever possible. id’s are more heavily used with JavaScript DOM code.)
   4. pseudo-classes: “Note: a:hover MUST come after a:link and a:visited in the CSS definition in order to be effective! a:active MUST come after a:hover in the CSS definition in order to be effective! Pseudo-class names are not case-sensitive.”
   5. !important wins. (Try to avoid this unless for example you’re fixing a browser z-order rendering problem.)
   6. all bets are off with syntax errors, missing semicolons, or mis-specified class name lists, so fix those first. See below.
8. do some reading online about block and inline element display. Some properties can only be applied to a block element, which usually means adding an enclosing div.
9. CSS uses the original C-style comments of slash-star. Invalid comment characters, like // and #, can cause surprising behavior. Firefox will log “Selector expected. Ruleset ignored due to bad selector.”
   “.

Note: if you’re paying for HTML or CSS, always validate it before payment. Even better, ask your designer to validate it weekly and before delivery.

Debugging Strategies

1. verify if there are any CSS media screen blocks that vary with resolution
2. verify the correctness of individual class definitions, especially lists. if “cascading seems broken”, most likely there is a syntactically-correct but stray ‘div’, ‘p’ or ‘input’ after a class name
3. once the CSS looks sane, you can debug problems by setting enclosing div classes to red or green and refresh your browser
4. if there’s multiple CSS files included, try varying the order
5. to debug rounded corners issues, try setting the background to black or white for maximum contrast
6. test on Firefox, Safari, Chrome and IE11. Budget twice as much time if you want to support IE9 and IE10
7. try overriding a CSS element or enclosing div with an inline style to narrow down a problem.

Emergency Fallbacks

If you’re on a deadline or don’t have story points for a CSS project, there are workarounds.

1. Although it’s better to write classes that apply to all elements, being more specific can fix individual form field problems
2. As a temporary fix, doing an inline style will guarantee what the element looks like.

Getting Done

1. if you’re not working solo, use the diff command to communicate changes to other developers and artists
2. coordinate the checkin. Note that artists often are not version control experts, so you need to find out what the natural flow is or somebody’s changes will get stepped on (seen it twice already.) Investing some time now could prevent big problems later

Little CSS Stuff Newcomers Get Confused About

Related Annoyances

1. maxlength doesn’t work on input type=number
2. it’s more difficult to left-justify and right-justify 2 items in CSS than with tables

Tools

uncss
jhead
CSS Stats
CompressPNG and tools family

TheRegister has an article about a Cisco recall on the ASR 920 Series Aggregation Services Routers PSUs

I enjoy reading TheRegister, but this article is a little light on research.

Looking around online, it turns out that PSUs are often designed for certain altitudes when using air as a dielectric and for cooling, and 2,000 meters is common. However, the current ASR 920 datasheet specifies 4,000 meters, hence the recall.

The real story is:

1. How did Cisco learn of the PSU problem? Device failure, or DC fire?
2. How many other models have the wrong PSU?

Various Configurations of the Cisco ASR 920

When you need to edit a PDF, you really need to edit a PDF.

The free Preview app that comes with Mac OS X can annotate and do some simple operations on PDF files, but does not have a feature to edit the actual text.

I tried the following free or trial PDF editors on Mac OS X 8.5 for editing text on a 30-page Firefox “print to PDF.”

iSkySoft Watermark

Multiple page support for Inkscape

Best Super Bowl that I can remember, with first Super Bowl Overtime.

The New England Patriots (QB Tom Brady) came from behind to win 34-28 over the Atlanta Falcons (QB Matt Ryan).

Atlanta scored 3 TD’s in Q2:

1. Freeman does 3 drives resulting in a flying landing in the endzone
2. xxx runs into endzone
3. did a 82-yard interception.

Patriots got a 41-yard field kick for the 3 points.

Lady Gaga’s half-time performance was good, with surprising acrobatics.

Then the Patriots scored 31 unanswered points to win.

Commercials ($5 million for 30 seconds) weren’t too good, although John Malkovich trying to get his vanity domain from a domain squatter was pretty good (squarespace.com.)

Seemed like mostly cell phone, car and VR-related ads.

W: Super Bowl LI

How to fix “SuccessSuccess” Wi-Fi issue on MacOS X Mavericks temporally

The big news from the SpaceX launch of 10 Aireon Iridium 2G “Next” satellites is that ADS-B was also included on each satellite.

ADS-B is used for tracking and sending ATC digital information to airplanes. The FAA has mandated that almost all aircraft will install ADS-B transceivers before 2020, at a cost of $5,000 to $1 million per airplane, plus downtime.

Since there’s 150,000 registered US aircraft and thousands of foreign airliners, that just isn’t going to happen with the existing number of Mx shops and remaining 1,080 days. 🙂

These are fairly large satellites at 860 kg each:

PSA:

“Changes to eBay Bucks Rewards Program starting January 1, 2017
Effective January 1, 2017 the Base earnings are changing from 2% to 1%.”

Guess I’ll be advising sellers to wait for 8% or 10% eBay Bucks days.

Last time I’ll see one of those.

Basic Economy Fares Don’t Lower Ticket Prices, They Increase Ticket Prices
The Champions of the 401(k) Lament the Revolution They Started

Avweb has an interesting article on ‘Extreme Maneuvering’ about practical applications of the FAA commercial aerobatic maneuvers (chandelles, lazy 8’s, steep spirals) that mentioned “rolling G’s.”

A rolling G occurs when you maneuver an aircraft in more than one axis at a time, causing the airframe or wing to twist. The rolling G design limit is considered to be 2/3 of the normal G limit, according to FAR 23.

Although I performed the commercial maneuvers during my Commercial Airplane practical test and Citabria checkout, I wasn’t really aware of two things:

1. airframe twisting from rolling G’s can more easily exceed a plane’s load limit. Those limits would be lower in older aircraft, possibly already damaged, than newer ones. It’s important to load the airplane one axis at a time.
2. the commercial maneuvers can be used to reverse in a box canyon. I know a private pilot who crashed in a box canyon (he luckily survived) because he knew of no course reversal methods, so this is handy to know.

Chandelle (Climbing, Reversing Turn) Animation

The asymmetric lift, resulting in a torque, caused by the ailerons travelling up and down simultaneously with yawing and pitching maneuvers is believed to have caused several airshow accidents in older airplanes, shearing the wing spar. Contributing factors are the acceleration rate of the control movement, airspeed above maneuvering speed, Va, and wing and fuselage harmonics. Sideslip also affects G limits.

It would be difficult to calculate actual rolling G limits without destroying several aircraft to build a mathematical model. There are a number of reasons for that, but primarily the problem is that dynamic torque must be calculated for multiple types of members, including spars, fuselage skin, and especially attach points. The latter is tricky because attach point hardware may be very strong in one axis, and very weak when loaded off-axis (or corroded.)

pprune.org: Why is Rolling G dangerous?, Normal G limits vs Rolling G limits?
W: Chandelle,
Ice and Tail Stalls

I don’t often go to the movies, but saw ‘Rogue One’ with a date.

The first half seemed kind of slow and disconnected, dealing with various rebel assassination plots (!) on Jedah and Eadu. Good visuals but weak story-telling.

The protagonist, Jyn Eros, portrayed by Felicity Jones, must be a pretty bad actor to have her mother killed in front of her, yet convey being unsympathetic and uninvolved throughout most of the film – I’d rather watch paint dry.

However, the second half dealing with the invasion and destruction of the Imperial base at Scarif and testing of the Death Star was riveting.

Darth Vader’s brutal but ultimately futile light-saber fight scene at the end will please action fans.

And seeing a youthful Princess Leia (CGI) at the end receiving the Deathstar plans was a nice surprise.

The rebels’ companion robot, a re-programmed Imperial model named K-2SO, was intelligent and funny enough to be unsettling. Admiral “Fishlips” Raddus a Mon Calamari, also provided comedic distraction.

Admiral “Fishlips” Raddus. Photo Credit: Lucasfilm

W: Rogue One
IMDB: Rogue One
Can we talk about that final Darth Vader scene in Rogue One?
bbc.com: Rogue One is Star Wars for Better and for Worse
Rogue One: Meet Admiral Raddus, thecharacter inspired by Winston Churchill
Behind the scenes of ‘Rogue One’ with director Gareth Edwards

The story behind Princess Leia’s hairstyle

Keywords: General Fishlips

The sorry tale of the Cessna 162 Light Sport Aircraft (LSA) has finally concluded. The remaining 80 airplanes have been crushed with a backhoe outside the the Chinese factory, including the installed engines and avionics.

It’s believed that liability insurance and parts support didn’t pencil out for the accountants. Crushing solved the liability problem, and also any agreements with suppliers like Continental and Garmin prohibiting resale.

Kind of a shame they couldn’t have sold them to the Chinese government for $1 for use in flight training in exchange for indemnity from lawsuits.

Of the original 1,000 projected orders, 200 were actually delivered and 80 crushed.

There were many problems with the 162:

1. capabilities were Day and Night VFR, not IMC.
2. 1,320 pounds gross weight only left room for one American after full fuel with this design
3. flight schools required a separate check-out, even if you had 152 and 172 experience. This involved additional expense and searching for a slender CFI.
4. price was high for flight schools given the above limitations. The 162 had teething problems, and some owners had to replace the ADHARS twice
5. assembled in China, unlike most trainers.

Cessna Scraps Unsold Skycatchers
Crushing More Than Airplanes
Skycatcher’s Demise: Barely a Ripple [2013]
W: ADHARS

Finally.

TransAsia Shuts Down Amid Safety, Financial Problems

Cirrus SF50 Vision Jet – almost actual size!

It’s a short-range single-engine 4-seat passenger jet for $1.5 million with a parachute that can be operated for $660/hour.

I’ve been following the news on this during the last decade of development. General Aviation (GA) moves slowly, but the SF50 and HondaJet show that eventually small aircraft do get certified.

The numbers:

1. 300 KTAS
2. 2036′ runway
3. 67 knots stall speed
4. FL280
5. FIKI
6. cabin height is only 4.1′.

Obviously it’s intended for existing Cirrus owners who want to step up to a jet.

It uses a Williams FJ33-5A jet engine, similar to the original $800,000 Eclipse 500 jet plans. Williams is a cruise-missile manufacturer, so has lots of manufacturing experience with small jet engines, but not much experience with passenger airplane maintenance.

The Cirrus SF50 is not like this, a Boeing Business Jet (BBJ)

China has bought most of the American GA manufacturing capacity out of bankruptcy in the past decade to position itself for growth in the emerging Chinese civilian market, including Continental Engines (2010), Superior Air Parts (2008), Mooney (2013) and Diamond Canada (2016.)

So far, that has resulted in much-needed investment, though it’s unclear what the long-term implications are for the USA.

avweb.com: Cirrus SF50 Vision Jet: Learning From the Past
aopa.org: Hourly operating costs of 45 jets compared
Mooney’s Fortunes Tied to China
Luxury VIP jets: How the super-rich fly
avweb.com: Checking The China Acquisition Score Card
Cirrus Delivers First Vision Jet

Disbelief at the death of Prince at the relatively young age of 57.

Prince was a musical genius, certainly one of the giants of this century – he wrote, sang, was a virtuoso of 2 dozen instruments, and played guitar at the level of Jimi Hendrix.

He could perform with everybody, or nobody, yet chose to mentor female musicians, introducing them by name in his shows.

I saw one of his shows, but wish I had gone to more.

For business reasons, he never allowed his catalog on YouTube, but there’s a few links from TV performances that indicate his brilliance and show him “bringing the funk”:

Prince & 3RDEYEGIRL Perform ‘She’s Always In My Hair’
Prince Saturday Night Live Full Performance (2014)
Prince playing piano over ‘Summertime’ at Soundcheck, Koshien, Hyogo Prefecture (1990)
PRINCE BET Interview with Tavis Smiley(1998)
“Stand Back” – Stevie Nicks (writer/vocals) with Prince (synths/drum machine), inspired by Little Red Corvette

cnn.com: Prince’s vision for lifting up black youths: Get them to code, Prince’s Death: Latest News
W: Prince
Nicole Scherzinger sings Purple Rain Tribute
Mayte Garcia on the Prince you didn’t know
PRINCE THE MAN BEHIND THE MUSIC ~ FULL DOCUMENTARY

There were a few major earthquakes this weekend:

• Ueki, Japan – 6.2 (foreshock)
• Kumamoto, Japan – 7.0
• Ecuador – 7.8

Hundreds of aftershocks have occurred in Japan.

You would think that Californians, of all people, would be concerned with earthquake safety, but the LA Times has reported on a building safety cover-up involving thousands of older schools and office buildings which will pancake in a major quake.

How Risky Are Older Concrete Buildings?
LA Times FAQ: Concrete buildings, earthquake safety and you
Non-ductile Concrete Buildings

I used to write telemetry collection software for the Space Shuttle, rockets and balloons, but even I watched the SpaceX barge landing with disbelief as the rocket smoothly rotated in all 11 or so degrees of freedom at the same time – no hesitation or staging before the touchdown.

It was like watching a really big lawn dart plant itself. 🙂

twitter: SpaceX
HN: SpaceX Launch Livestream: CRS-8 Dragon Hosted Webcast
theRegister: SpaceX finally lands Falcon rocket on robo-barge in one piece, SpaceX’s Musk: We’ll reuse today’s Falcon 9 rocket within 2 months

A few pieces of MH370, a Boeing 777-200ER, have recently been found on a Mozambique beach, and confirmed as authentic parts.

Their excellent condition and relatively large sizes indicate that the accident wasn’t a high-speed impact with an obstacle or water.

As a commercially-rated airplane pilot, my opinion is that leaves:

1. explosion or decompression
2. descent (or phugoid) into ocean at relatively low speed
3. “graveyard spiral dive” pulled the wings off.

An interesting question would be, “In modern airliners, especially Airbus, anti-phugoid software is deployed. How would that affect an uncontrolled airliner?” Sully said that anti-phugoid software in his Airbus prevented him from slowing descent before impacting the Hudson River.

MH370 Debris Storm
Tourist who found debris was searching for MH370
Turbulence V-Speeds
Australia Confirms Mozambique Debris Came from MH370
MH370: Debris found in March ‘almost certainly’ from missing plane
Investigators Report On MH370 Debris Analysis (2016)
ATSB MH370 Report [pdf]

ATSB Image

Congrats to the Laser Interferometer Gravitational-wave Observatory (LIGO) team for directly detecting gravitational waves for the first time.

LIGO was the NSF’s most expensive project, and took scientists basically from the 1960’s to 2015 to fully realize – initially nobody believed it was possible to actually build this instrument.

Two detector locations with perpendicular 4 km 4-mirror laser interferometers were able to detect gravitation waves from a billion year-old blackhole collision:

Direct Gravitational Wave Measurement of Two Black Holes Merging in 1/10 of a second!

The graph is very interesting and raises the questions:

1. do the pre-impact lobes represent the outer limits (presumably thinner than the center) of the black holes merging?
2. the slope of the lines in the main chirp are very steep … are those spikes much taller (or infinite) than we can resolve?
3. what do the small post-impact lobes mean exactly?

(The local speed of light in a medium is a constant, while gravitation waves distort space, thus changing an interference pattern.)

Basic science is always valuable, but just a few of the reasons why this experiment is important:

1. confirm the equations originally proposed by Einstein in 1915 for gravitation in the GTR and Standard Model
2. confirm experimentally that light and gravitation waves have different propagation characteristics
3. develop the technology to make observations at the sub-proton level
4. study large-scale cosmic events (black holes, colliding galaxies, supernova, binary star systems)
5. study the time of the Big Bang, as gravitational waves are not filtered like EM waves
6. confirm or deny cosmic observations and theories made in the EM spectrum, and provide advance notification of occurring events for study in the EM spectrum.

More generally, measurement tools are the highest form of technology, whether for time, space, EM, or gravity. Any investment of time or money in measurement tools is easily repaid 1000x. For example, the GPS system is the result of accurate time measurement using “atomic clocks.”

This decade is an exciting time for science, as several major terrestrial and space instruments come online or are upgraded.

It will be interesting to see if anybody develops a table-top model of LIGO. Experiments in the 60’s with non-laser methods were susceptible to ambient vibrations, but we’ll see. Cryogenics would likely have to be involved since random atomic motions are larger than the signal being acquired.

LIGO Detects Gravitational Waves for Third Time
Gravitational Waves Detected 100 Years After Einstein’s Prediction
SIGNAL PROCESSING WITH GW150914 OPEN DATA
W: LIGO
Reddit AMA
LIGO black hole echoes hint at general-relativity breakdown
On the time lags of the LIGO signals HN
Gravitational waves from a binary black hole merger observed by LIGO and Virgo
LIGO Architects Win Nobel Prize in Physics
LIGO and Virgo announce the detection of a black hole binary merger from June 8, 2017

Today was the last chance to see Babbage’s Difference Engine at the CHM in Mountain View before the owner makes it private again.

The Computer History Museum has certainly matured into a world-class museum over the years.

The docent talked for about 45 minutes. Unfortunately, it was displayed at the end of a hallway. So 100+ people with kids and strollers jostled to get a view.

It’s very impressive in person – consists of 8,000 parts, weighs five tons, and measures 11 feet long, moderately noisy and mesmerizing to watch. The cranker used a moderately strong rowing motion.

Babbage, in building the first computer, did not have the hindsight to start with a smaller version first. Thus he never finished building a working model despite a decade of funding from the British government and the remaining days of his life working on it.

CHM did a fantastic job on the DEC PDP-1 and IBM 1401 display rooms. Only about 50 PDP-1’s were made, so to have a working model is amazing.