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Trivia Testers

Galileo notwithstanding, with raindrops, the bigger they are, the faster they fall. (For objects of that size, the surface area to volume ratio dictates the extent to which it will overcome air resistance and viscous drag as it falls. Larger drops have a greater terminal velocity.) But when a raindrop falls faster than about 18 miles per hour (in still air) what will usually happen?

Where the Force Started
The US Air Force originated in

  1. 1907
  2. 1918
  3. 1926
  4. 1947

Answer: Uh...well, all four. Some purists might say choice A, some might say D. One could conceivably trace its roots back to the Balloon Corps of the Army of the Potomac, or 1863 when Congress authorized the Civil War Signal Corps. Primarily concerned with visual signaling, the Signal Corps also supplied telephone and telegraph communications, began the use of telephones in combat, used combat photography, and of course, balloons. But the precursor to the US Air Force originated on August 1, 1907 as the Aeronautical Division of the Army Signal Corps (later called the Aviation Section of the US Signal Corps). Total personnel strength was three: one Captain, one Corporal, and one Private First Class (who later went AWOL). In July 1914, the Aviation Section of the Signal Corps had 30 aircraft and 40 pilots. By 1916, total personnel strength was 311, and by 1918, it was about 195,000. The Signal Corps was the branch of the US Army that took charge of "all matters pertaining to military ballooning, air machines, and all kindred subjects." However, after America entered World War I in April of 1917, it was evident that the Signal Corps wasn't the right organization for our combat aviators, and the War Department created the Army Air Service on May 24, 1918. The forerunner of the US Army Air Corps, the Army Air Service was separated from the Signal Corps and made a separate combatant arm of the US Army in 1920, and renamed to the US Army Air Corps on July 2, 1926. A revised, expanded (and again renamed) Army Air Force replaced it on June 20, 1941. Although the Lampert Committee of the House of Represetatives had first proposed an Air Force independent of the Army and Navy back in 1925, the National Security Act which made it official wasn't until September 18, 1947.

Aces High
Arrange in their proper respective order the approximate numbers of American aces in the First World War, World War II, Korea, and Vietnam.

  1. 100, 1300 ,50, 3
  2. 30, 150, 150, 30
  3. 60, 600, 150, 15
  4. 20, 100, 500, 20

Answer. A. The ambiguity inherent in precisely quantifying the numbers of aerial victories in the confusing and (to say the least) stressful situation of aerial combat, where simply staying alive had to take precedence over keeping an accurate tally of who shot whom, and when, must be taken into account. Quantifying numbers of downed aircraft often bordered on the indiscriminate, and during the First World War many pilots flying for America originally came from the French Air Service or the Royal Flying Corps. (The same applied to a few of our WWII aces from the UK.) During the Korean War, about half of the "aces" (using the definition of five or more victories) had also scored during prior service in WWII. (So if you count everything, the number of US aces in Korea could be 56, or if you only considered US aerial combat that took place during the conflict, it might be only 41.) During Vietnam, Randy Cunningham and Richard Ritchie are credited with five kills, while Robin Olds had "only" four. But he still had thirteen victories from his service during World War II, two decades before! Does that mean he was no longer an "ace"? (I don't think that would be entirely fair, do you?) So the point is that such numbers will always be approximate. However, one general observation emerges from these numbers, vague though they are: During WWI, the few top American aces had scores of about twenty. During World War II, there were far fewer (less than two percent) credited with that many or more, and during Korea, the top aces could claim somewhere about 15. And to put things in perspective , Captain Charles D. DeBellevue, the leading US Air Force combat ace in Vietnam, shot down six enemy planes.

Fairly comprehensive listings of aces from all wars, and all countries, can be found on many web sites. One example is this Fighter Pilot Aces List. Based on these data, the approximate numbers and victories of all American aces would look something like this:

Ignoring for the moment the trailing thousand of so from WWII (those having less than a dozen victories) allows a closer look at relative performances during the other three wars. Apparently, the greater scale and refined lethality with which war was waged in the air may have been responsible for more "kills" in WWII, but then despite the smaller numbers in the relatively smaller conflicts in Korea and Vietnam, victories got progressively "harder" to come by as each side got better at tactics and defensive measures.

Raindrops Keep Falling On My Head...
Galileo notwithstanding, with raindrops, the bigger they are, the faster they fall. (For objects of that size, the surface area to volume ratio dictates the extent to which it will overcome air resistance and viscous drag as it falls. Larger drops have a greater terminal velocity.) But when a raindrop falls faster than about 18 miles per hour (in still air) what will usually happen?

  1. It will evaporate
  2. This is the point where raindrops change shape from a relatively flattened (oblate) blob of water to the familiar teardrop shape.
  3. It will break up into smaller raindrops (each of which will slow down somewhat).
  4. Nothing happens. You just get pelted real hard. This is a trick question.

Answer: C. Raindrops are formed when the innumerable numbers of tiny droplets within clouds grow in size as moisture from the surrounding air condenses on them, or as they coalesce with other droplets during their descent. Raindrops vary in size from about 0.02 in. (0.5 mm) to about 0.2 inches (about 5.5 mm). Rarely, drops as large as 0.33 in. (8 mm) have been reported during thunderstorms, although this is not as well documented. (The appearance of such large raindrops is always associated with convective activity, turbulence, and strong updrafts, which would allow raindrops to continue to grow.) From the time they leave their parent cloud, evaporation occurs, and if the cloud is high, the air is dry, and the raindrops are small enough, they may evaporate completely, before reaching the ground. When that happens, it's called virga. Generally though, the "average" raindrop (which falls at about 11 mph) holds together until its velocity reaches about 18 mph (barring turbulence, the relative motion of updrafts or downdrafts, etc.) After that, it breaks up into smaller raindrops. They actually do change shape, except that up to about 2 mm in size, raindrops are generally spherical, after which they become more oblate and their bottoms flatten out, until they come to resemble the top half of a hamburger bun in shape. (In addition to that, they oscillate in shape somewhat as they fall.) Once they reach about a fifth of an inch (about 5.5 mm) in size, raindrops become unstable and they break up. So, the next time you're caught in a rainstorm and it feels like a fusillade of bullets, really isn't that bad.

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