Pop Goes the Weasel
Regarding surplus military jet airplanes and ejection seats, which of the following statements is (are) true?
- Surplus military aircraft of any type must have their ejection seats deactivated prior to civilian use in the private sector.
- Only propeller-driven reciprocating or turbine engine aircraft are allowed to have ejection seats, once they have been decommissioned and begin use in the private sector.
- There are no unilateral prohibitions against the use of ejection seats in privately owned surplus military jet aircraft, even when they are operated by the use of pyrotechnic devices.
- Ejection seats are allowed, however only stored-energy “spring” types are allowed for aircraft having an Experimental Exhibition certificate, such as that assigned to the majority of jet trainers in civilian hands.
Don’t Leave Home Without It
You’re on an extended ocean-crossing flight. Which of the following might be a legitimate consideration regarding an addition to your list of carry-on items?
- suntan lotion to counter the extra ultraviolet radiation
- a couple of bananas for the extra sodium
- if you take your shoes off for any length of time near the end of the flight, a shoehorn
- earplugs
It’s All In the Wrist
If it weren’t for the pitch change of a helicopter’s main rotor blades at different points along their revolution around the main rotor hub, a helicopter would, at moderate speeds,
- roll over and crash
- reach a forward speed limit of approximately 15 knots
- only be able to fly in a circle
- begin flying straight up
The Answers…
Pop Goes the Weasel
Answer: You would expect that pilots who haven’t been exhaustively trained in the proper use of a device by which they could potentially punch out over a populated area would be absolutely forbidden from flying such a machine having a live, armed ejection seat. After all, who knows where the pilot-less airplane might fall? You would think that part of the dues one must pay to enjoy such an exquisite toy would be the requirement to ride it on down, unlike those pilots in the employ of Uncle Sam who get to “give it back to the taxpayer”. But you would be wrong! Live, pyrotechnically armed ejection seats are allowed. However, their upkeep and inspection regimen isn’t trivial. (Of course, if you have to ask the price…) As one example, take the L-39 Albatros jet trainer, originally manufactured by Aero Vodochody in the Czech Republic. There are about 220 of this type alone currently registered in the US. The FAA has an entire advisory circular (AC 43-209, “L-39 Albatross Military Jet Recommended Inspection Program”) devoted just to this very select group, in fact. In it, in its Appendix 2 (L-39 Ejection Seat/Canopy Inspection Program), it describes safety precautions for inspecting the seat and its ejection mechanism. The answer is choice C.
Don’t Leave Home Without It
Answer: The amount of increased ultraviolet radiation one encounters in or near the stratosphere on one airline flight or even a few isn’t terribly significant. The ozone layer, at between 20 to 25 Km, will still be well above you. (However, if your flight is in the southern hemisphere and you over-fly Antarctica, you might want to read up a bit more.) Your electrolyte balance won’t get too terribly out of whack, either. Scratch choices A and B. But if you’ve heard about deep vein thrombosis (essentially a blood clot in an extremity which has remained immobile for an extended interval), you might have had a suspicion about choice C (not that it has anything to do with your shoe size). Several hours in an airline cabin, even with its relatively subdued volume of whooshing air, can bring one to wish for a bit more peace and quiet, but that’s a matter of personal preference, not necessity. Some of the more well-endowed corporate jets can have passenger cabin noise levels below 50 decibels-normal conversation is about 60 dB-while some noisier airplanes have takeoff noise levels over 100 dB. Give yourself credit on that one. But there’s another one that most people wouldn’t think about: their shoes. The fact is that your heart is not the only thing in your body contributing to the circulation of blood; your leg muscles do, too. Bring on prolonged periods of sitting on your duff, and blood as well as other fluids will collect at the lowest point: your feet. If your shoes are a fairly tight fit to start with, leaving them on during the entire flight will prevent your having to pull out the shoehorn, although it won’t stop your feet from swelling up. The phenomenon isn’t confined to airliners of course; it can happen on trains and automobiles, also. You can mitigate problems associated with long periods of inactivity by exercising while seated or simply by getting out of your seat occasionally.) And incidentally, our feet swell somewhat during a normal day of activity, anyway. That’s probably why the American Podiatric Association suggests that our shoe purchases are best made in the afternoon. (They can be a half size, or even a full size larger.) So either C or D counts on this one.
It’s All In the Wrist
Answer: This one was a give-away. In case you didn’t catch on or didn’t notice my coy inference in the subject title, I’ll just flat-out tell you: it’s choice C. (Helicopters are dynamically unstable, but they’re not so unstable that they would immediately roll over and crash.) But here’s what’s going on: When in forward motion, a helicopter’s main rotor blades need to vary their angle of attack as they complete each rotation about the rotor hub. If a helicopter’s main rotor blades didn’t flap and feather automatically (either from hinges designed for the purpose or the entire span teetering to one side), whenever it was in forward motion, the dissymmetry of lift between the advancing blade or blades and the retreating blade(s) would cause the helicopter to begin doing exactly the same thing that a boomerang is designed to do: fly in a circle! (A boomerang of course has no articulating assemblages, and the greater lift on the advancing blades causes it to make its otherwise mystifying return to whence it came.) The answer is choice C. The upward flapping of the advancing blade causes its effective angle of attack and lift to be reduced; the downward flapping of the retreating blade has the opposite effect. The result is equalized lift on both sides. At excessive speeds, the limit of angle of attack on the retreating blade is eventually surpassed, and…choice A is pretty close (though the helicopter would begin to pitch upward, first).
