Speed Zone
We have supersonic jet fighters, but are they (or any other type of aircraft capable of supersonic flight) ever flown faster than Mach 1 over the continental United States? More than one may apply.
- Military aircraft flying combat air patrols are authorized to exceed Mach 1 on an as-needed basis.
- Regular supersonic flight over populated areas was discontinued in the 1960s.
- There are designated supersonic corridors and other areas in different locations around (and outside of) the Continental U.S. (such as in central Florida, where double sonic booms are often heard from returning Space Shuttles)
- Sonic booms cannot be heard when the aircraft is above FL 600
Answer: A and C. In general, only US Government aircraft can go supersonic over land. (But there are provisions for civil aircraft to exceed Mach 1 in Appendix B to CFR Title 14, Part 91.817, and such instances usually involve a darned good reason for some entity in the private sector to do so.) As to where NASA and Uncle Sam’s best boys and girls can give their airplanes a workout, one example is the 17-mile wide and 240-mile long Black Mountain High Altitude Supersonic Corridor, passing over Edwards AFB in California and extending towards Nellis AFB near Las Vegas, Nevada, over the Lake Mead National Recreation Area. It extends from Ventura County, California to Clark County in Nevada, and passes through portions of several other counties. It overlaps the R-2508 complex near EAFB, across the northern section of R-2515. (Actually, there are three designated corridors in that general area.) USAF aircraft going supersonic usually notify either the FAA High Desert Terminal Radar Approach Control facility (call sign JOSHUA) or the Air Force Flight Test Center Radar Control Facility (call sign SPORT). Also, these aren’t just Top Gun jocks doing it because they feel a Need For Speed. Each training base has a Letter Of Agreement on file with the FAA, and maintains a “boom log” to keep track of every supersonic flight. Additionally, authorized aircraft are actually permitted to go supersonic anywhere in the restricted airspace at Edwards, if they need to. They must however remain sensitive to the impact that may have on people who live beneath their route of flight. In the wake of the terrorist attacks on September 11 2001, F-16s on combat air patrols have exceeded Mach 1 (choice A), in order to catch up to airliners during air-rage incidents. But during most non-emergency peacetime conditions, overland supersonic flight activity is usually above 30,000 feet. (See USAF Instruction 11-202, Volume 3, Chapter 5, Section 5.7.1, and AFI 13-201, Supplement 1, Section 2.11, “Supersonic Operations”.)
As to choice D, whether a sonic boom is heard or not is a function of air pressure and temperature, humidity, load factor on the aircraft, terrain, Mach number of the aircraft, planform, inlet type, etc. According to Marta Bohn-Meyer (to whom I directed this specific question regarding any limiting altitude for sonic boom generation), even from 80,000 feet, sometimes the sonic boom from the SR-71 was hardly noticed on the ground…and sometimes, it was incredibly strong. (Marta has, as she puts it, the distinction of being the world’s only SR-71 crewmember who happens to be female.) Actually, as a reader pointed out to me, when he was flying F-104A’s in the 1950’s, they didn’t have to go supersonic to create a “sonic boom.” At about 0.98 Mach, a four to five-g pullout produced one, sometimes. (Marta’s answer to this was that in any turn, parts of the airplane are traveling faster than others, and the air around it goes faster, so if one measures Mach in the right places, the record will show that part of the airplane is supersonic. Although the boom requires supersonic flight, near-supersonic flight will cause the air to rumble. If you add load factor, which accelerates the air over the wing, you can and do go supersonic and can get a LIGHT boom. If you are low enough, it may be strong enough to feel or hear.) Marta has conducted research on exactly this subject for NASA. Here is what the vicinity of the Black Mountain corridor would look like on a sectional chart, followed by its actual depicted location.
Unusual Airplanes
What is unusual about N60094?
- It is currently the only registered experimental aircraft not fitting into any known category (the most commonly used term being “flying saucer”).
- It is the oldest airworthy aircraft in the United States.
- It is the only private aircraft in the United States that ever transported a US President while in office.
- It was last flown by Elvis Presley.
Answer: B. N60094 is a Bleriot XI monoplane, manufactured in 1909 (and listed in the Experimental category). It belongs to the Rhinebeck Aerodrome Museum. (There are two other Bleriot airplanes in the United States; one is in California and the other is in Oklahoma, but these are not flying.) It is the second oldest airplane in the world that is still airworthy. (However, according to information obtained from the Aerodrome, only the front and rear third are original; the wings, elevators, and horizontal stabilizer have been rebuilt.) The original aircraft had crashed in 1910; its remains were later removed from a junkyard and were stored for many years before Cole Palen returned it to flying condition. It is powered, as was the original, by an Anzani engine.
No Strings Attached
The connection between the helicopter and concert piano is that:
- the auditory alerts for the Army’s Comanche helicopter were played on a grand piano.
- someone cut a grand piano loose at 3000 feet from a cargo helicopter near Seattle, prior to a concert by Country Joe and the Fish in 1968 (and again for an MTV stunt out in California City in the fall of 2000, with pretty much the same results).
- if it weren’t for Sergei Rachmaninoff, Sikorsky Helicopters probably wouldn’t exist.
- A and B
Answer: C. Igor Sikorsky was born in Russia in 1889, built many airplanes for the Czar, became fairly wealthy, and built the world’s first four-engined airplane. But when he fled the Russian Revolution, he arrived flat broke in America. Six years later in 1923, with $800 in savings, he started the Sikorsky Aero Engineering Corporation. It was a rather humble emigre operation, strategically located…um…on a friend’s Long Island chicken farm. There were some twenty mechanics, several of whom were quite illustrious refugees, calling each other Baron, Count, or General, because they had been (although today that might conjure visions of asylum inmates). They made tools, as well as airplane parts, out of anything handy; their first project was a twin-engine passenger plane, the 29A. (It was Sikorsky’s 29th design, and the A simply stood for America.)
But you might say that the famed composer and pianist Sergei Rachmaninoff was instrumental (pardon my highbrow guffaw) in getting helicopters off the ground. Besides being a very tall man, and having phenomenally large hands–he could play a 13th on a piano keyboard?Rachmaninoff had another kind of reach: he kept a watchful eye out for his fellow Russians. He had heard about Sikorsky, and on the very day that he first came to see the “factory” he gave Sikorsky a check for $5000 (about $100,000 today) with (dare I say it) no strings attached. This enabled Sikorsky to relocate to a hangar at Roosevelt Field, and rescued his teetering company from the brink of oblivion. For that, Sikorsky made Rachmaninoff the Vice President of his company, and the two went on to become close personal friends. Fittingly, Sikorsky’s 29A made its first profit ferrying two pianos from New York to Washington. Not many years after Rachmaninoff’s generous assistance, Sikorsky sent Rachmaninoff a check for that $5000, plus interest.
