Nine Years Later and No Closer To Shipping: Terrafugia Transition’s Continuously Slipping Delivery Date…

Terrafugia ship date slip chartTerrafugia incorporated in May, 2006 and now nine years later in May, 2015, their Transition aircraft remains the same “two years” away from first customer delivery as when they started.  Considering Terrafugia’s history of delivery estimates, prospective customers should probably toss their most recent estimate in the heap along with all of the other missed estimates that they’ve published.

This list of their most prominent public announcements about expected delivery of the first Transition aircraft to a customer shows no progress toward shipment.  It was compiled in hopes of discerning a trend that might indicate whether the company was closing in on a ship date; they’re not converging.  The estimates show quite the opposite; Terrafugia’s statements have stuck to using a date that’s always about two years from today (average 21.0 months, stdev.p 3.7), regardless of when today actually falls.  October, 2008 represented the high point for customers when Terrafugia proclaimed that they were only 15 months away from starting shipments.  On average since then, Terrafugia has pushed their deadline further into the future and assiduously avoided converging on a real ship date.

Terrafugia ship date slippage

Terrafugia Transition’s Estimated Ship Date moves in lock step with the calendar and they appear to be settling in on a delivery “estimate” that’s consistently “24 months in the future”. If Terrafugia were converging on a ship date, then the orange curve should flatten out and the blue one should curve down toward zero as press releases indicated progress toward an actual shipment.

It appears that either Terrafugia employs really poor forecasters, they’re trying to hide something from the public, or maybe it’s just far harder to bring an airplane to market than newly minted college graduates could have imagined?  Their announcements, whatever the motivation, really push the line between optimism and deception.

Update (later May 11, 2015): Only Terrafugia’s press releases indicate they’re making no progress. Their accomplishments do show advancement, just not at the optimistic pace their press releases would have you believe. They’ve certainly learned a lot from the Proof-Of-Concept and first prototype vehicles as well as from their positive FAA and DOT regulatory decisions.  Hopefully their press officer learns from this post too.

Pebble vs. WeLoop Tommy Smart Watch Specification Comparison

WeLoop, in cooperation with DealeXtreme, will release released the US$70 $75 Tommy smart watch on September 15, 2014. This table compares the technical specifications of the Tommy and Pebble smart watches; superior specs are highlighted in bold text.
Edit 2014-10-13: Updated prices
Edit 2014-12-11: WeLoop will release an SDK

Spec Pebble WeLoop Tommy
Price US$100 (Original), US$200 (Steel) US$75
Image Pebble originalPebble Steel WeLoop Tommy smart-watch
Dimensions    52 × 36 × 11.5 mm       46 × 34 × 10.5 mm (Steel) 45 × 34.5 × 11 mm
Case colors (Steel) Stainless steel in brushed silver or matte black;
(Original) Polycarbonate in fly blue, hot pink, fresh green, black, grey, white, orange, or red
Polycarbonate in black or red (white in the future)
Watch band(s) included (Steel) Proprietary watch band connector; stainless steel band in brushed silver or matte black matching watch plus a black leather band.
(Original) Standard 22m watch band connector; color matched 22mm band included: Silicone (black) or TPU (white, blue, pink, green).
Color matched TPU band, proprietary band connector.
CPU Cortex-M3, up to 80MHz Cortex-M0
RAM 128KB SoC 24KB (8KB SoC+16KB external)
Flash memory 4MB (8MB in Steel) external + 512KB SoC 512KB external + 256KB SoC
CPU Power usage  32 µW/MHz 13.36 µW/MHz
Battery 7 days, 130mAh 21 days, 110mAh
App store 1000’s of custom apps and watch faces
(including: pedometers, find my phone, RSS readers, swimming lap coach, home control, remote controls, and much, much more)
Update Dec, 2014: WeLoop announced they will release an SDK, date unknown
Common built-in apps Caller-id, accept/reject calls, notifications, multiple analog & digital watch faces, music control
Unique built-in apps Multiple alarms, RunKeeper display Notification filtering, pedometer, find my phone, camera remote
Sensors 3-axis accelerometer, magnetometer, ambient light, thermal 3-axis accelerometer
Crystal Material Scratch resistant polycarbonate (Original) Mineral glass
Gorilla Glass (Steel)
Backlight White Blue
Compatibility iOS & Android
Bluetooth 4.0+LE
Display Sharp 1.26″ Memory LCD, 144×168 monochrome pixels
Output Vibration
Waterproof 5 ATM

Personalize the Meaning of “Retina Display”

Apple’s Retina Display marketing broadly publicized the concept of retinal acuity, but each person’s vision differs; so, just how small do those pixels need to be for your vision?

Fortunately, inverting the well known Snellen notation (e.g. 20/20 corrected vision, 20/30 uncorrected vision, etc…) gives your personal visual acuity in minutes of arc. For example, inverting 20/20 = 1 meaning that 20/20 vision can resolve 1 arc minute sized details.  Similarly, someone with 20/60 vision has a visual acuity of 60/20 = 3.3 arc minutes; 20/15 vision can resolve 15/20 = 0.75 arc minutes.  Go ahead and calculate your own visual acuity in arc minutes.  Ready?

OK, let’s see how tiny the pixels on a screen need to be to make it a retina display for you.  To do this, we’ll calculate the smallest pixels that you can resolve at a given distance. For example, if you have 20/20, or 1 arc minute, vision and hold a smartphone 11 inches (28 cm) away, you’ll be able to resolve individual pixels if there are 313 pixels per inch (123 pixels/cm) or fewer; if it has more pixels than that per inch/cm (i.e. higher pixel density & smaller pixels), then it’s a “retina display”.

Here’s how to calculate the minimum number of pixels per distance to match your eyes (fill in your visual resolution in place of “1“:

tan(½ × 1 arc minute) × 2 × 11 inches = 0.0032 inches (or the inverse of 313 pixels per inch (ppi) or more)
tan(½ × 1 arc minute) × 2 × 28 cm       = 0.00814 cm (or 123 pixels per cm (ppcm) or more)

Spreadsheet formulas for this looks like:

<resolvable pixel> = tan(radians(0.5 * <your arc min.>/60)) * 2 * <distance>
<pixel density> = 1 / <resolvable pixel>

In more detail: to calculate the pixel size, s, opposite the viewer divide the angle, a, in half to give a right triangle with the viewing distance, d, adjacent to the angle and the length of ½ of a pixel opposite. 1 arc minute = 1/60 degree. Then with basic trigonometry:

tangent (angle) = opposite/adjacent
tangent (½ a= ½ s/d
½ s = tan( ½ a ) d
    s = tan( ½ a ) 2 d

Tangent of half of the angle time the distance equals the spacing needed

If you were looking at a television 5-½ feet away instead, then you’d only be able to resolve 52 ppi (20 ppcm):

tan(½ × 1 arc minute) × 2 ×   66 in.  = 0.0192 in. or 52 ppi
tan(½ × 1 arc minute) × 2 × 170 cm = 0.0495 cm or 20 ppcm

A 42-inch diagonal, full HD television (1920×1080) also happens to have 52 pixels per inch; therefore, when viewed from 5-½ feet or farther the pixels begin to blur together for 20/20 vision.  Homework: how close/far should you sit from your television to turn it into a “retina” display? Enjoy!

Snellen acuity Visual resolution (arc minutes) Retina display, iPhone Retina display, TV
(11 in, ppi) (28cm, ppcm) (9′, ppi) (2.75m, ppcm)
20/200 10 31 12 3 1
20/100 5 63 25 6 3
20/70 3.5 89 35 9 4
20/50 2.5 125 49 13 5
20/30 1.5 208 82 21 8
20/20 1 313 123 32 13
20/15 0.75 417 164 42 17

Spaceballs, Comic-Con & nubrella’s new backpack style umbrella

Submitted for your consideration: Nubrella’s backpack style hands-free umbrella (above), and Lord Dark Helmet seen visiting Comic-Con (right). Spaceballs fans everywhere, how cool would it be for them to add a Lord Dark Helmet, blacked-out model to their lineup!

Obfuscated Javascript.Explained()

And this, of course, evaluates to the string “fail”.
— Marcus Lagergren (@lagergren) May 23, 2013

Rewrite to show the four (string)[subscript] uses:
 (![]+[])        [+[]]
+(![]+[])        [+!+[]]
+([![]] + [][[]])[+!+[]+[+[]]]
+(![]+[])        [!+[]+!+[]];

Then evaluate each color-coded expression:
![]+[]  => "false"
+[]    => "0"
+!+[]  => "1"
!+[]   => 1

That third string really exercises those square brackets!
[![]] + [][[]] => "falseundefined"

Finally, we’re ready to ‘fail’:
 f + a +  i + l

XKCD Subways of North America – with !

XKCD comic #1196 – Subways has a great map of the subways in North America linked up by some fantastic, mythical branch lines. I started collecting the actual maps for all of the subways, until I recalled that the The Urban Mass Transit Systems of North America map from Yale Professor Bill Rankin on his web site Radical Cartography (ca 2006) has already done the work. That map scales, rotates, and geographically maps the subway systems to allow for accurate comparisons. Mr. Munroe probably got his inspiration from that map!

In case you’re interested, here’s the collection:




San Francisco (BART)

San Francisco (MUNI)




New York, New Jersey (PATH)


Mexico City

Google Glass’ Retina Display? Almost…

Google Glass Explorer edition

Google Glass’ Explorer hardware

The Explorer version of Google Glass pairs a Himax HX7309 nHD LCOS microdisplay with optics to project a “display [that] is the equivalent of a 25 inch (63.5 cm) [diagonal], high definition screen [viewed] from eight feet away.” and the UI-guidelines say to “target a 640×360 resolution” using a default text size of 40 px.

When viewed through the Explorer’s optics,  display appears like a 25 inch, 16:9 screen.  is 20 inches (51 cm) wide and when viewed from 8 feet (244 cm) away, each pixel subtends just over 1 arcminute in your visual field (67 arcseconds = 3600*degrees(2*atan(20/640/2/(8*12)) ). Typical 20/20 vision has a resolution of about 1 arcminute (60 arcseconds) and so Glass pixels are very close to qualifying as a “retina” display. The whole screen, however, fills just 14 degrees of your visual field. For reference, an iPhone held screen 11 inches (28 cm) away fills 18 degrees (or 20.6 degrees for an iPhone 5).

By the way, the TSA is going to have a field day with sousveillance!