2018-02-26 5 min read


A followup from last week, and a hat tip to Jim, who called me out on trying to call out The New Yorker (always a risky move) on the engineering of flight (something that I am *not* qualified to do). As Jim points out, the article's wording ("Because the top side of an airplane wing is curved, while the underside is flat, the air above moves faster than the air below, and the wing rises.") was vague, making my complaint about its accuracy a bit futile. Also, my own wording was sloppy. To clarify:

  • Airfoils come in a variety of shapes and configurations. Some are convex on top and less so (flat or otherwise) on bottom; Some are bent/curved but have constant thickness (like paper airplanes and traditional cloth sails; Some are tear shaped but symmetrical (like modern America's Cup boats' wings).
  • Pressure differentials do matter, but even lift itself is a necessary-but-not-sufficient ingredient in the recipe of flight. Also, the traditional explanation for how airfoils create pressure differentials (the "equal transit" theory; see the first item in Wikipedia's List of Common Misconceptions in Physics for an explainer) is just plain incorrect.
  • Newtonian mechanics + angle of attack matter a lot; to describe flight without mentioning them is a bit silly. See the Wikipedia page for Lift or this NASA K-12 explainer on what makes airplanes go up.

Lastly, I'll refer you to the Explain XKCD on airfoils, which sums the whole situation up nicely.

Thanks again to Jim for engaging me. I'm a generalist, and proud of it - but for pretty much any subject linked to in The Prepared, I *always* enjoy hearing from specialists :)

Planning & Strategy.

  • Another scathing postmortem of Immelt-era GE, this time focusing on the former CEO's judgment and leadership style. As Jordan wrote by email: "If I try to summarize the article's thesis, I read it as, 'GE over-indexed on shrinking markets and set its targets unrealistically high.' I buy that.

     I see two critical mistakes of the Immelt-era:

     1) A claim that GE was simplifying, when it fact it was increasing its complexity. Sure, GE shed its consumer units...but it also made giant acquisitions (Baker Hughes, Alstom) and managed to thoroughly frustrate its customers with its own complexity. The story I tell myself about these acquisitions was that it was the only way the heads of many GE divisions could find a way to make their revenue numbers (that is to say, by adding the receivables of their acquisitions).

     2) The Digital COE strategy sucked. They started with a platform strategy when they really needed to start with a division-by-division product strategy. They designed complexity into that org from the beginning, and it stymied their ability to get to market quickly and demonstrate results, particularly with O&G—as the article points out.

     The thing the article misses (as does almost everybody in our corporatist culture) is what role and accountabilities does the board play in these choices? It's so easy to blame Immelt, but I don't think it's unfair to guess where the insistence on these revenue targets were coming from..."
  • Oerlikon and Boeing are working together to create standard materials & processes for (presumably laser based) metal powder bed fusion, the most established method of metal 3D printing. This sounds to me essentially like a push to improve metal AM's manufacturing readiness level, which (even considering advances since this) is appropriate; I'm curious, though, how this will align with the standards that ASTM F42 is developing.
  • Trump's budget proposal eliminates $125MM from the Manufacturing Extension Partnership, "a program to support small manufacturers that officials say created or protected more than 100,000 jobs in the last fiscal year alone."
  • A handy little .bashrc configurator.

Making & Manufacturing.

  • A good video of Nablus/Nabulsi soap being made. I found this to be frustratingly un-ergonomic, though I suppose it's difficult to justify such affordances when you're manufacturing in disputed territory (the West Bank). I recommend watching this at 2x speed - except the packaging part, which is better in real time.
  • A Japanese forestry products company plans to build the tallest wooden building, which will eventually be about 2/3 as tall as the new World Trade Center. "The total construction costs are expected to be approximately ¥600bn (£4.02bn), almost double that of a conventional high-rise building. But Sumitomo Forestry Co said in a press release the total would probably be brought down by technological advances between now and the 2041 scheduled completion date."
  • Making an agate teapot.
  • Human-knit samples of patterns that were generated by a neural network.

Maintenance, Repair & Operations.

Distribution & Logistics.

  • When Planet Labs' Electron rocket was successfully launched last month, it included a feature not publicized before the launch: A kick stage, which was used to put part of the payload into a circular (as opposed to elliptical) orbit.

Inspection & Testing.


On Mr. Stephen, the fast supply vessel (cost: ~$2.7MM/year) that SpaceX is using to attempt recovery of Falcon 9 nose fairings (cost: $3MM/each).

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