Understanding Product Reliability Through Bathtub Curves
The Analog #121
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There are two ways to think about reliability in a product. 1) reliability from development to production, where early prototypes often fail due to design flaws or manufacturing uncertainties. Over time, these issues are resolved but reliability can dip again when scaling during development phases and production. 2) the bathtub curve, a classic model that maps failure rates across a productās lifespan: early "infant mortality" failures, a long period of stable operation, and eventual "wear-out" due to aging and stress. This chapter from NASA provides an excellent overview of reliability engineering, covering failure types and statistical methods used to predict system performance.
We sometimes mix up the terminology ourselves, so hereās a simple way to remember: failure is when a product stops performing as expected, and reliability is the probability that it wonāt.
Have you ever asked yourself, āWhat is this connectorā? From the Electronic Connector book, an interactive chart of the most commonly searched connector types. Simply look for any connector type, and click to learn more about its specifications, vendors, and key features. A personal favorite is the lever wire splice, which we learned is not actually called a WAGO connector (thatās just the vendor name) and also comes in an in-line version.
A great video from Breaking Taps highlighting why designing space hardware is deceptively hard. He walks through a case study demonstrating why even a basic component like a hinge that works fine on Earth can fail in space for reasons you wouldnāt expect. A simple press-fit pin holding two aluminum sections together seems solid, but under the intense vibrations of launch it can work itself loose and in some cases lead to cold weldingāwhere identical metals bond together in vacuum conditions after their oxide layers wear away. The best designs avoid metal-on-metal contact, using engineered polymer bushings like Teflon or graphite-filled PEEK to prevent wear or galvanic corrosion related failures.
Despite a background in civil engineering, some of Brian Potterās most popular work with Construction Physics are on the subject of commercial aircraft development. Building commercial aircraft is notorious for its massive financial risk, with development costs in the billions and a market that sells only around 1,000 jets per year. To put cost into perspective: āThe $186 million Boeing spent developing its first jet airliner in 1952, the 707, was $36 million more than the company was worth.ā In his most recent post, he looks into the viability of Boom Supersonic actually building a commercial supersonic airliner. He does a great job outlining the extremely high bar for capital efficiency that Boom will have to meet going forward to make commercial success.
Heat people, not places. This is an interesting breakdown of how older heating systems worked compared to modern counterparts that predominantly rely on convection to warm entire spaces by heating the air. There are three types of (sensible) heat transfer: convection (the heating of air), conduction (heating through contact), and radiation (heating through EM waves). The old systems of providing heat relied upon radiation and conduction, where convection was a by-product. People found simple ways to stay warm: Dutch foot stoves, small wooden boxes with hot coals inside; the Afghan korsi, a low table with a heater underneath and a heavy quilt draped over it; and the Chinese kang, a raised brick platform heated from below, doubling as a bed.
A really cool video from the CEO of Zipline: how they use fog machines in cold conditions to simulate icing as a stress test for their second-gen drone system.
Sponsored: Summit Interconnect is hosting a webinar (Thursday, 3/13) on thermal management techniques in PCB designāregister here.
Startup News š
Google co-founder Larry Page has quietly launched Dynatomics, a new manufacturing startup applying large language models to automate product design and manufacturing. From early, somewhat vague reports online, the company aims to ācreate highly optimized designs for a wide variety of objects and then have a factory build them.ā The startup is led by the former CTO of Kitty Hawk, an electric air taxi startup that Page invested $100M in before closing down.
A product launch and a fundraising announcement in the battery sector:
Pila Energy emerged from stealth and announced a āmesh homeā battery designed to deliver intelligent, automatic backup power throughout the home. It's a scalable 1.6ā3.2 kWh lithium iron phosphate (LFP) battery pack capable of continuous 2400 W output and brief surges up to 7800 W. Details around funding are light, but the startup has secured early-stage backing from climate-focused investors. The founding team previously led product development at Span.
Moonwatt has raised $8.3M in seed funding for its sodium battery technology designed to make solar power storage more efficient and profitable. Moonwatt offers a scalable, cost-effective sodium-ion battery storage system that boosts solar power plant efficiency by up to 80%, and profitability by storing excess energy for high-demand periods. Founded by ex-Tesla colleagues, Moonwatt seeks to fill the gap in dedicated solar storage solutions, with plans for a European pilot in 2026 and commercial rollout by 2027. The round was co-led by Daphni and LEA Partners, with participation from Founders Future.
CarbonQuest has secured $20M in funding to expand its modular carbon capture systems, which trap CO2 emissions from buildings and onsite power generation for industrial reuse. Founded in 2019 and based in Spokane, WA, CarbonQuest plans to use the funds to accelerate system deployments following six successful commercial installations. The round was led by Riverbend Energy Group, with additional investments from Energy Capital Ventures and Aligned Climate Capital.
STAX Engineering, U.S.-based maritime emissions capture and control company, has secured $70M in funding, $60M in debt financing and $10M through a SAFE. The investment will scale its emissions capture technology and launch carbon capture trials with UK-based Seabound at the Port of Los Angeles. The trials integrate Seaboundās carbon dioxide capture system with STAXās mobile emissions control units to reduce vessel greenhouse gas footprints, with full-scale deployment planned for late 2025.
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