Tag Archives: aerodynamics

Time-Warp: The Unfolding Story of 4-D Printing

Image of printing press with legs holding a quill
It’s probably something like this.

4-D printing remains in its early stages, It’s certainly too early to tell if  it’s anything more than a buzzword, let alone if its promise will translate into practicality. But the sorts of people who bet on these kinds of things are betting on it.

And why not? Suppose a structure could unfold itself, like origami. Imagine if walls could flex or stiffen in response to shifting loads, or if a buried pipe could change shape to accommodate varying water flows — or to pump water via peristalsis, like your digestive system. Through 4-D printing, nothing is set in stone unless you want it to be.

How 4-D Printing Works

Blood Will Tell: A Blood Spatter Analysis Update

Eduard Piotrowski of Poland’s University of Krakow published the first major blood spatter study in 1895, but its impact was limited to a few inventive European sleuths like German chemist Paul Jeserich and French forensic scientist Victor Balthazard. The American legal system did not adopt spatter analysis as evidence until the landmark case of State of Ohio v. Samuel Sheppard, and the field did not truly take off until the 1970s, after forensics expert Herbert MacDonell published his influential Flight Characteristics of Human Blood and Stain Patterns.

Blood spatter analysis has undergone major refinements in methods and language since then, including a recent and growing shift toward incorporating computers. I discuss several of these shifts in my 2015 update of Shanna Freeman’s 2007 article:

How Bloodstain Pattern Analysis Works

Ramjets: Making Mock of Mach

1946 ramjet test. Image courtesy NASA.

The faster you go, the less inclined the air becomes to get out of your way. This simple fact, which stood for years as an impediment to breaking the sound barrier, can also be ingeniously harnessed to create an engine capable of zipping along at supersonic speeds without the fuel weight required by rockets.

In this article, I trace the history, science and engineering behind this revolutionary “flying stovepipe,” from its theoretical birth during the biplane era to its modern military and commercial offshoots. By the time we’re done, you’ll understand…

How Ramjets Work

Going the Extra Mile (on the Same Tank of Gas)

Photo of a gas price sign.
Photo by Ildar Sagdejev

Call it ecodriving, hypermiling or plain old frugality, people today are trying every trick they can think of to wring a few extra miles from a drop of gas. Unfortunately, most fuel-saving tips range from the dubious to the downright dimwitted. Even the ones that work — such as making only right turns — veer into the ridiculous. In this Top 5 list, I’ve separated the classics from the clunkers and saved you the trouble of doing your own Mythbusters episode. Read on to discover….

Everyday Driving Tips to Save Fuel

The Art of the Bunt: Deconstructing Dickey’s “Tricky Hit”

Aki Iwamura lays down a bunt. Photo by imagesbyferg.

Bunting, says Bill James of Sabermetrics fame, is “the only play in baseball that both sides applaud.” But years ago, every player – even sluggers like Babe Ruth and Mickey Mantle – used bunting as a fundamental part of the game, and some coaches still prefer the bankable bunt when it comes to advancing runners, especially when a weak hitter steps to the plate.

Whatever your viewpoint, there’s little doubt that bunting is an art. Read on for the ins-and-outs of this venerable and controversial technique.

How Bunting Works