Pound of Retention

Feb 21, 1998

RAY: We're back. You're listening to Car Talk with us, Click and Clack, the Tappet Brothers, and we're here to discuss,of course, cars, car repair, and-a, and-a.

TOM: And-a.

RAY: The new puzzler.

TOM: Yeah, I can hardly wait.

RAY: Well, I got an e-mail the other day from...

TOM: You read your e-mail now?

RAY: From -- not really?

TOM: Someone printed it out and handed it to you.

RAY: I got an e-mail the other day from someone who severely castigated me for not having good puzzlers every week.

TOM: Oh, really?

RAY: Yeah, I mean yes, I was.

TOM: That's unfair.

RAY: You know you've only got one puzzler a week to do. I mean how could it be so lousy. I mean what kind of a lazy bum could you be?

TOM: He's got a point, doesn't he?

RAY: He does.

TOM: Hit home didn't it?

RAY: It did. And if you really wanted to convey that to me Dad, you should have just called me on the phone. We could have discussed it.

TOM: E-mail was not necessary, and that phony e-mail name you...

RAY: All right, here it is. Where do I start? Now should I start at the beginning?

TOM: Yeah.

RAY: Sometime in the late 1930s, Germany's and perhaps other countries' aeronautical engineers were working on a device. Are you paying attention? All the details are embedded. All the essential information is embedded in this puzzler. A device -- and the device did the following. It took water vapor, which is one of the products of gasoline engine combustion, and would condense it into water and save it. You say well, not such a big deal. Well, it would save it in an interesting way. It would save it in such a way that the amount of water saved would be exactly the equivalent in weight as the amount of fuel that the engine burned. So as the engine burned, a pound of fuel or a kilogram of fuel...

TOM: You saved a pound of water.

RAY: It would save a pound of water and discard the rest. You got it?

TOM: Yeah, that way the plane always weighed the same.

RAY: Why would you want to do this?

TOM: I suppose if I want to answer it, why not? Why would you want to do this?

RAY: That's the question.

Answer: 

TOM: I remember saying something like that way the weight of the plane would remain constant.

RAY: You did say that.

TOM: Yeah.

RAY: Why would you want it to remain constant you might ask yourself?

TOM: The only thing I could think of was that it must have been a weapon of some kind and you wanted the weight to remain constant because there was some kind of a guidance system which wouldn't work properly if the weight kept changing.

RAY: Buzz bombs you're thinking of? Right?

TOM: Something like that.

RAY: No. That's not it either.

TOM: Nothing like that, huh?

RAY: So, as you might guess, as the engine burned a pound of fuel, a pound of water would be saved. Right?

TOM: Yeah.

RAY: You've come to that conclusion.

TOM: Yeah.

RAY: And the rest would be discarded, of course. The question is why would you want to do this. That was the question and obviously you've come upon weaponry which is not it. Airplanes was not it. Our engineer Jonathan Marston came up with submarines. Ooh. That's good. Huh?

TOM: Oh, that would be good.

RAY: Except why would you want to save water? You're what? You're immersed in water.

TOM: Wait a minute. You said aeronautical.

RAY: There you go.

TOM: And submarines aren't aeronautical, John.

RAY: Well, he wasn't paying attention. He's engineering the show. Damn it. He's got a lot of other important things to do, but he got the jist of it.

TOM: Yeah.

RAY: But he was close, I said.

TOM: Oh, dirigibles.

RAY: Exactly.

TOM: Of course.

RAY: At that time they had switched over from hydrogen as the levitating medium.

TOM: Yeah.

RAY: Which was a little dangerous.

TOM: Little dangerous.

RAY: To helium which was much safer, but very expensive.

TOM: Yeah.

RAY: And needless to say as you consume fuel and the craft becomes lighter and lighter --

TOM: You got to spew the stuff out.

RAY: You got to spew the stuff out, but you can't do that because it's expensive. So, you what you want to do is save some of the by-products so you keep the weight of the vehicle the same.

TOM: Oh, I love it.

RAY: Isn't it great? Dale Margie or Margy sent that in.

TOM: Actually, he's answered for me a question I've been struggling with for, uh, lo these many minutes which was the stoichiometry involved. That assumes, the whole question and answer assumes that you produce far more water.

RAY: It's 18 to 1.

TOM: Really?

RAY: Eighteen pounds of water.

TOM: No.

RAY: To every pound of... And that is the source of a greenhouse effect.

TOM: Of the greenhouse effect.

RAY: That is. We're adding water to the planet and in doing so, we're slowing down. Pretty soon the days are going to be 25 hours. We're slowing down the angular velocity of the planet.

TOM: Well, we knew that because of the billboard effect too.

RAY: Well, that too.

TOM: That's 26 hours.

RAY: Right.

TOM: Add that to it.

RAY: Yeah.

TOM: So, there's the billboard effect and the roof snow theory and --

RAY: All that. OK?


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