Answers to Pop-Rivet Quiz Test 3

1. It's D: 15 degrees, with opposite cyclic; a measly 6 without! But if it's shut down and plunked on a hillside with a crane somehow, it is a whopping 42 degrees! (That's independent of cyclic, of course. Being shut down, there's no collective raising the effective center of gravity.)

2. It's A: Jack be nimble, jack be quick, or Jack be day-ed. Robinsons are great, the engines are de-rated and almost never fail, but you can get carb ice...And unfortunately, they've got very LOW rotor ineria. Once you get below 70% rpm, it's over. And the rate of decay below that is much more rapid. (Some pilots have argued that the percentage rpm below which you cannot go is in the high 60s. We´d prefer to be a bit less optimistic--more conservative--and stick with the 70% figure.)

3. Of course, in the other case, you might not want to discuss it. It's B: Or, maybe B and D. (There really IS a window.)

4. The answer is (mostly) A and B. Sodium is the alkalai metal that "burns" in water.

5. The correct choice would be C. (That's my final answer.)

6. The answer is A . . . maybe. (Actually it's A, definitely.)

7. The answer, of course, is D. (Hmmm...AeroSpheroid?)

8. The answer is C. (On this scale, frictional and viscous forces greatly eclipse Coriolis forces, and a draining bathtub is really just cyclostrophic flow (a balance of pressure gradient and "centrifugal" forces.) When we see clockwise flow around an atmospheric high (up in the Northern hemisphere) we are really looking at a broader category called "geostrophic" motion--again a balance of pressure gradient and Coriolis forces. Coriolis forces (an apparent force, really, as it cannot cause a motion) only show up in nature at a scale of several hundred meters. This might be compressed down to dozens of meters in a fluid with absolutely no "vorticity", in a controlled chamber. My intuition tells me also that it would "work" better using a fluid that was less dense than water. Not good grounds for a funding request, though.

9. The answer is D. I mean, C.

10. The answer (which you probably guessed from the impassioned verbosity) is D--all three.

11. The answer is (B) When you think about the atomic numbers of hydrogen, oxygen, and nitrogen, it makes sense, after all!