I love everything about lists - to-do lists, bucket lists, inventory pick lists - they're all fantastic. For years, I started every year, week, and day with a list of intentions. Lists served as a clear declaration of what I set out to do, like a love letter from my past self telling me things that will make life better - read x number of books, meet someone new, go to a concert of a band you don’t know.
But I'm experiencing this sudden desire to deviate from all my lists. Something has changed, and it’s probably me. The advice that my past self lovingly wrote down doesn’t seem as valuable as the decisions I can make in the moment. Instead, I’ve been asking the question “What’s grabbing your attention right now?”, and chasing that. I still value the care and intention that goes into making lists, but I’m learning that my current self may just know more. In the past, I would have kept working through lists despite the shifts I was experiencing. Now, I'm letting my lists evolve over time - keeping some of the old parts, mixing in new parts, and ending up with something that is improved with age.
This newsletter, in some ways, is a list of items that captures the writer. When I look at my previous issues, it’s almost like reading something that someone else wrote. It makes me realize that they’re a list of things that were fascinating and fully consuming me – but only in the moment. And it’s kind of special to think of each issue as a moment in someone’s life. It’s even more special, to share this moment in my life, with you.
The most clicked link from last week's issue (~9% of opens) was a post about being glue in a technical organization, and taking on the less glamorous (and less promotable) work that sticks a team together. At The Prepared, we help our Members stick together. Two things that they can look forward to this week:
- In the Reading Group, we're starting Virginia Postrel's The Fabric of Civilization: How Textiles Made the World. Tune in asynchronously in the #reading-groups channel on Slack (and on Fridays on Zoom) to discuss the history of perhaps the most human technology (clothes) and how innovations in textile manufacturing have repeatedly shaped and upended society.
- In the #tools channel on Slack, folks ask for advice and post little love letters to things they're working with, from drill augers to analytical precision weights to electronics prototyping connector systems. Today we're also giving away an open source e-paper there; join us there by 17:00 ET and put your hat in the ring!
Planning & Strategy.
- I appreciated the depth of history in Flying Blind: The 737 MAX Tragedy and the Fall of Boeing by Peter Robinson. I worked at Boeing when the MAX was grounded, and appreciated the layers of nuance and complexity in the book compared to other media coverage. Robinson covers 100 years of history, including every Boeing commercial airplane program from 707 to the 737 MAX and a ton of context to the McDonnell Douglas merger. He also provides fun aviation trivia, like how 23,000 Boeing SPEEA union members held the largest white-collar strike in US history, which featured the greatest slogan: “No nerds, No birds.”
- Wet-bulb temperatures are incredibly important in the context of climate change, as they define the points at which sweat can no longer evaporate from the human body. When wet-bulb temperatures exceed 35°C, the body is no longer able to use sweat to regulate its temperature, resulting in overheating and, over time, death. There have been at least ten events that have exceeded a wet-bulb temperature of 35°C, and as the earth warms, they’re expected to occur more and more frequently. In a recent study on human health in 35°C environments, participants had to “swallow a tiny radio telemetry device encased in a capsule that measured their core temperature while performing tasks mimicking basic activities of daily life, until they could no longer maintain their core temperature without overheating.”
- A holacracy is a decentralized, self-organized team.
Making & Manufacturing.
- Metallic whiskering is a phenomenon that occurs in some metals where fuzzy, hair-like strands separate from the base material and can cause unexpected shorts in electronics. Whiskering is common in vacuum environments, adding a layer of complexity to material selection for in-space applications, especially those near sensitive satellite optical sensors. NASA has a list of materials that whisker, including zinc, cadmium, tin, and silver. Related fun fact: Lead is added to solder to mitigate whiskering.
- MoS2 is a common dry lubricant used for its low coefficient of friction. What makes MoS2 interesting to work with is that its coefficient of friction is far from constant - it’s anisotropic, load dependent, and temperature dependent. This neat paper covers the performance of MoS2 in different environments.
- I found this high-level overview of different types of mold release agents really informative. In the composites shop at work, Frekote, a solvent-based semi-permanent release agent, is a common mold release used to prevent adhesion between a part and its associated tool. Recently, I’ve been exploring paste wax release agents that are permanent barriers between the part and the tool and it’s been interesting to see the different off-the-shelf options available.
Maintenance, Repair & Operations.
- During the installation of an MRI machine at Morris Hospital near Chicago, 120 liters of liquid helium was vented into the building. Soon, something unexpected happened: many iPhones and Apple Watches stopped working entirely. This investigation into helium’s impact on iPhone components is fascinating - helium molecules are small enough to penetrate and disable the oscillator. While the behavior was initially pretty mysterious to everyone on site, it turns out the iPhone user guide acknowledges the problem.
- Watch a tear-down video by Becky Stern of the Gen 2 and Gen 3 Oura Ring, featuring a walk-through of the electrical components with David Cranor (who often writes this newsletter), and a neat accordion battery assembly.
Distribution & Logistics.
- Joby Aviation, one of the many electric vertical take-off and landing (eVOTL) startups, has received its Part 135 Air Carrier Certificate from the FAA. While this certification is just one of many required prior to approval for passenger flight, this milestone is a big deal given the recent changes to the FAA certification for eVOTLs.
A study analyzed how long different metals stay in circulation before becoming lost as a means to understand the future of metal recyclability. While loss during ore production averages around 15%, there are some notable (and alarming) exceptions:
About half of the cobalt, which is highly desired for many types of batteries, ends up being lost during production. Indium, used in many semiconductor products, sees losses hit 70 percent. And many metals have production losses of 95 percent or higher: arsenic, gallium, germanium, hafnium, scandium, selenium, and tellurium.
Inspection, Testing & Analysis.
- A neat and in-depth paper on deriving snow depth from space-borne lidar.
- While the capstan or belt friction equation, which relates frictional forces and tension, is common in the rock climbing and shipping world, this Hackaday article demonstrates its use with robotic cable mechanisms.
- Understanding slosh dynamics - the dynamics of fluids in moving containers - is critical when sizing and laying out aircraft fuel tanks, rocket fuel tanks, and cargo ships.
- A fantastic history of the manufacturing of biscuits and India’s love for them.
- A brief overview of the development and production of QuikClot, a popular military grade blood clotting agent.
- The Space Force allows for longer mustaches than the Air Force.