Archive for June, 2026
Don’t get burned by sunscreen myths
For those of us living in the Northern Hemisphere now is the time of maximum danger from exposure to sunlight. Thank goodness for highly effective sunscreens. On June 9th, the FDA approved a new chemical that filters ultraviolet rays—bemotrizinol (BMT). So, based on the experience of Europeans, who have used BMT for decades, those Americans who use sunscreen will soon be even better protected.
Unfortunately, many here in the USA either never use sunscreen (admitted by nearly third of all adults in a 2024 Yahoo News/YouGov 2024 survey) or they fall prey to these myths*:
- It is OK to skip sunscreen on cloudy days. “UV rays penetrate clouds,” says dermatologist Shari Lipner.
- Sunscreen is only needed if you are outdoors a long time. Lipner says “Incidental exposure adds up over time.”
- SPF in cosmetics protects you. Lipner says “it’s best viewed as a small bonus.”
Here are some suggestions on maximizing sunscreen effectiveness based on research reported in my July 1, 2018 blog post Are you seeing red sorting out how much sunscreen to apply and at what strength?:
- FDA statistics indicate that an SPF of 50 blocks 98% of UV rays versus 93.3% for a 15 SPF sunscreen. If SPF 50 is too pricey, consider downgrading to an SPF 30 offering 96.7% protection.
- To be effective, sunscreen must be applied to a thickness of at least 2 milligrams per square centimeter—about one-fifth the depth of a piece of paper. Although this seems very thin, most people only put on about half that amount, so you’d best apply your sunscreen twice. Doing so will also reduce the chances of missing exposed areas. This happened to me on a two-day paddle down the Saint Croix River bordering Minnesota and Wisconsin. I missed areas on my foot not covered by my water shoes and suffered painful burns on both ankles.
Bottom line: Go ahead and skip or skimp on sunscreen—your dermatologist’s boat payment depends on it. ; )
*Source: “How to Fight Sun Damage,” Consumer Reports, July-August, 2026 .
Wright Brothers’ brilliant launch of modern aerospace experimentation
Posted by mark in engineering on June 7, 2026
In late April my wife Karen and I made a pilgrimage to the Wright Brothers National Memorial—accomplishing a lifelong mission of mine. I’ve worked for decades helping aerospace scientists with their design of experiments (DOE). For example, a few weeks ago I helped a US Air Force project engineer set up a DOE to characterize the flowfield of a jet via testing at Hypervelocity Wind Tunnel 9.
According to a 2010 Defense Visual Information Distribution Service (DVIDS) press release (cited below with the quote), Tunnel 9 compresses nitrogen to 30,000 pounds per square inch and heats it to 3,000 degrees Fahrenheit to create a pressure ratio of about 1 million. Who knows how much more T9 can do now—16 years later.
“Wind tunnels, the tools used to simulate airspeed environments to test flight capabilities, have come a long way since the Wright brothers built a box with fans to test a kite model.”
– Ian Graham, author of Wind Tunnel Explores Dynamics of High-Speed Flight.
Though use of wind tunnels for aircraft development dates back to 1871, the Wright brothers revolutionized the use of these devices for testing during their pioneering studies in 1901. Of all the amazing artifacts at the Memorial, I was most impressed by the lift and drag measurement equipment—see these described and pictured at this NASA post. With this test capability in place, the Wright brothers achieved a design breakthrough that enabled their great achievement of the first flight of a powered, manned, and controlled heavier-than-air aircraft on December 17, 1903.
If you have not been to the Wright Brothers National Memorial, I highly recommend doing so, not just for the history, but also to take in the epic surroundings of North Carolina’s Outer Banks.