Why would any predictions of sunrise and sunset times for your local area, whether obtained from your new GPS display, the Daily Planet, or even the Nautical Almanac, be wrong?
- because they don’t include the effects of the eccentricity of the earth’s orbit
- because they don’t account for orbital eccentricity, and atmospheric refraction
- because they assume a sea level horizon
- They’re not wrong. This is just another blasted trick question!
The Boeing 717
A prototype of the venerable Boeing 707 launched the honored lineage of the Boeing 7-7 series of airliners when it made its maiden flight in July of 1954. The Boeing 727 was introduced into service in February, 1964. Since then, aside from that one gap, the series has continued uninterrupted. The commercial revenue service history of the 737 fleet began in 1968. In late September 1968, the first 747 rolled out of the Boeing factory. Boeing turned its first 757 loose early in 1982. The first 767 emerged from the Everett Washington Boeing plant in August of 1981. In June 1995, the first Boeing 777 entered revenue service. But what the blazes happened to the Boeing 717?
- There actually was a Boeing 717 detail specification, on paper, but its number was altered to patronize the whim of those in power, so a Boeing 717 was never made.
- The numbering sequence was originally intended to increment by 20, and only after the 727 was it changed.
- The number was intentionally skipped to cater to the whim of the then-president of United Airlines, a potential Boeing customer who favored another airplane manufacturer (which is basically choice A), however there actually now is a Boeing 717, although it didn’t see the light of day until after the 777.
- There was a 717, but the prototype was destroyed in an accident during flight testing. There were also no standing orders, so Boeing dropped it, and at that point it doubled its series increment from 10 to 20 (which was, of course, later changed).
Which among the following would you guess to be true?
- The Goodyear blimps have actually been around (no pun intended) continuously, since 1945.
- There are fewer persons possessing a “lighter-than-air” category rating for airships (okay, blimp pilots) than there are astronauts.
- The term “blimp” is believed to have onomatopoeic origins.
- The “effective landing weight” of the Goodyear Blimp can often be just 100 pounds.
- Airships are the only type of powered aircraft certified for flight without seat belts.
Answer: Sunrise is when the top of the sun appears on a sea level horizon; sunset is when the top of the sun sinks just beneath it. These times are dependent upon latitude, longitude, and the day of the year. And of course, they also depend on the local terrain. Published sunrise and sunset times are determined without considering the local geography however; they always assume a sea level horizon (yup, choice C). Also, due to atmospheric refraction, whenever you see a sunset, you’re looking three minutes into the past; the sun had already set, three minutes earlier. And when you see a sunrise, you’re also seeing the future (again, about three minutes worth), for the same reason.
The Boeing 717
Answer. If you are familiar with airline history, you probably guessed that the answer is choice C. There was indeed a Boeing 717 specification, and in fact it was used in preliminary negotiations with United Airlines. The president of United at that time was a William Patterson, and he strongly favored Douglas Aircraft. He had even said that he would never buy a Boeing 707 and that the 717 looked too much like a 707. This information reached those at Boeing who were responsible for drawing up the specification documents, and with one quick change to the title page, the 717 disappeared and became a 720 series. Of course, another more modern Boeing 717 appeared, following the merger of McDonnell Douglas and The Boeing Company in 1997. The 717 entered a rigorous flight-test program in September 1998 and received joint certification a year later. The Boeing 717 became the first commercial airplane to receive a “Concurrent and Cooperative Certification” from both the FAA and Europe’s Joint Aviation Authorities. The first 717 customer was AirTran Airways of Orlando, Florida (a.k.a. ValuJet, in a previous incarnation), which took delivery of the first one quite a bit more recently, in September 1999. Actually, according to Barry Schiff, who wrote an entire book about the first Boeing jetliner (The Boeing 707, published in 1967), the full story is that at Boeing at least, the original 717 was the Air Force C-135. When United ordered the smaller and lighter 707, they did so only if Boeing would call it something else because they, United, didn’t want their board of directors to wonder why they, United, had originally ordered DC-8s and didn’t want to be perceived as changing their minds. So Boeing called the lighter model of 707 a 720
Answer: Ah, blimps! And who hasn’t seen the Goodyear blimp? Whenever one is around, they’re certainly hard to miss. The father of what was to become such a well known corporate presence was an MIT graduate named P.W. Litchfield, who began working for Goodyear in 1900. Both his influence within the company and his futuristic romance with airships as the future of air travel grew, and by 1926, as the corporation’s new president, he christened its first one, named the Pilgrim. (Thus these most well known and familiar leviathans have actually been around for about three-quarters of a century, so that knocks out choice A.) Although a string of airship tragedies in the 1920s and 1930s (most not widely known, but one which became so) marked the decline of airships from America’s skies, and the Goodyear fleet shrunk from six to just one by the late 1950s, a marketing inspiration to use a blimp’s ample real estate as a very unmistakable advertising icon and public relations emissary rose to the point where, at present, its television exposure alone earns Goodyear about three times the cost of upkeep. (Their estimated annual operating costs are about seven million dollars.) The fraternity of airship pilots is indeed a small one; they are truly fewer in number than astronauts. A search of the FAA Airman Registry turned up just 140 individuals who are ATPs, commercial pilots, or private pilots holding a lighter-than-air, airship rating. (There don’t appear to be any recreational blimp pilots.) Many of these have European addresses. As a double check, my contact at the Airman Registry in Oklahoma City informed me that the number was 137 (as of early February, 2004). As far as the astronaut corps goes, even in the US alone, there are indeed more active astronauts (meaning astronauts who are currently eligible for flight assignment, including those who are assigned to crews). According to SpaceDaily, since 1978, some 237 astronauts have undergone shuttle and Space Station training. According to NASA, as of early 2004, there were 143 active and management astronauts, about 40 payload specialists, 25 international astronauts, and 133 former astronauts who were still living. That totals to an even higher number. So…check choice B (for blimp, not bogus).
They were known as blimps even before the first of the Goodyear fleet glided by spellbound crowds. The etymology of the word “blimp” is thought to be that in 1915, a Lieutenant Cunningham of the British Navy playfully poked an airship during an inspection at an English airstrip. Upon hearing the sound it made, he conjured up a humorous word by which to imitate it. (So choice C would count as a “yes”, also.)
There are 203,000 cubic feet of helium inside the two Goodyear Blimps based on either side of the US. (These are the older GZ-20 models; the “Eagle” in Carson California, and the Starts & Stripes in Pompano Beach Florida.) The third one, the “Spirit of Akron” which is based at the Goodyear headquarters in Akron, Ohio, is the newer and larger GZ-22, having an approximate 248,000 cubic foot capacity. (There are also two in South America, and two more in Europe.) Even in the GZ-20, its vast volume of helium can lift over six tons, but of course that’s just about what the rest of the ship weighs, although the envelope alone accounts for a bit less than two of those. (That effective weight could possibly be minus a few hundred pounds, on a hot day, when the helium acquires “superheat”-helium heats much faster than air-or plus a few hundred pounds, during a rapid descent.) When a blimp is at its so-called “E.Q.” or equilibrium, of course, it’s seemingly weightless. For the famous blimps, each hundred pounds from EQ will account for a vertical movement of about that many feet per minute (up or down, accordingly). Since they tend to slow to a very stately rate of descent as they approach their mooring and ground crews, they really do float gracefully in with what would be a net weight which is probably less than yours (choice D). Oh and in case you’re wondering, it costs about $20,000 to fill one of these babies up. (Also, because of diffusion of helium through the envelopes of each blimp, their crew must add approximately 10,000 cubic feet of helium per month.) The US seems to have a monopoly on this second-lightest element; there are over 32 billion cubic feet alone in one underground Texas reservoir, known as the Bush Dome. (That’s enough to fill about 130,000 of even the bigger Goodyear blimps.)
But the point here is that being nearly neutrally buoyant, they don’t exactly trace a wild and precipitous path through the skies. And their pilots and passengers usually don’t buckle up, which might lead you to conclude that choice E is for real, also. After all, blimps, being the docile and stately airborne cetaceans that they are, would certainly seem the perfect candidates for an aircraft wherein one might not even find seat belts. But you would be wrong.. (Interestingly, all Goodyear blimps are certified for IFR flight, day or night.) There is a section (1413) regarding the use of safety belts in the airworthiness requirements for the type certification of normal and commuter categories of airships. But you don’t have to hunt down this esoteric document to punch a hole in choice E. Check out CFR Title 14, Part 91.107(a), which states the requirements for having seat belts made available, notifications for their use to passengers, and of course, when they must be worn. The exceptions are free balloons (naturally) and airships that are type certificated before November 2nd, 1987. So although Goodyear and their corporate clients might not use them, it isn’t true that every airship doesn’t.
This one was quite a windbag. (Sorry, I got carried away.) The correct choices are the three middle ones: B, C, and D.