****
Aluminum has a high specific strength (yield strength/density)—6061-T6's is almost four times that of the steel 304SS at room temperature. But the specific strength declines rapidly with temperature, becoming equal to that of the steel at about 475oF. (Burns). This temperature is reached with 134oF superheat at 105 psig or 48oF at 285 psig. While it is possible nowadays to find an aluminum alloy (NASA 398) that can tolerate higher temperatures (750oF), it was developed after the RoF. (Lee).
So aluminum is acceptable from a strength standpoint only for saturated steam (it was used pre-RoF in certain residential boilers) or low superheat applications, and its high thermal conductivity would actually be disadvantageous for a boiler wall, forcing use of additional insulation.
Magnesium is even less suitable for boiler use than aluminum; "the common alloys begin to soften and weaken appreciably on exposure to temperatures as low as 200oF." (keytometals).
Titanium would be better; the commercially pure grade CP2 has a specific strength exceeding that of 304SS until the temperature reaches about 800oF. (Burns). That said, the preferred material for boilers and steam pipes is carbon steel (coupled with pH control) for low temperatures and pressures, and stainless or other alloy steel otherwise.
For cylinders, see the discussion of weight reduction for internal combustion powerplants in part 2.
As previously noted, a steam powerplant for an airship needs a condenser. For condenser tubes, the principal desiderata would be high thermal conductivity and corrosion resistance (Kutz 185). The traditional material is a copper-based alloy. Here, if available at a reasonable price, aluminum would be quite helpful. Titanium's higher corrosion resistance compensates for its lower conductivity.
Insofar as radiators are concerned, copper has a thermal conductivity almost twice that of aluminum, but weighs more than three times as much. If the radiator is simply a surface sheet fastened to the keel or hull of the airship, then its structural strength isn't important. Whether copper or aluminum is used will probably turn on cost.
Conclusion
While the efficiency of a condensing steam powerplant is higher than that of the traditional non-condensing one used in locomotives, and can be improved by superheaters, reheaters, and feedwater heaters, it's still a bit inferior to that of the gasoline (spark ignition) internal combustion engine, and even more so to the diesel (compression ignition) one.
As noted, the airship steam powerplant designed by the Bureau of Aeronautics weighed in at over 6 pounds/hp. The substitution of aluminum for copper where possible would probably reduce the W/P to perhaps 4, but the "efficiency add-ons" will bump it up a bit.
Steam is certainly a viable option for those airship builders who do not have access to up-time internal combustion engines, or their newly-built counterparts, but there will be a performance "hit." If fuel is cheap and abundant, the efficiency gap can perhaps be disregarded, and for large airships, the relatively poor power/weight ratio is less of a concern, as required power grows as the square of airship principal dimension, and available power and lift as the cube.
The ability to exploit solid fuel, notably coal, is nonetheless a big advantage for steam. That will be important in countries that are rich in coal and poor in oil, such as England, France or Germany. And the ability to use agricultural waste (e.g., bagasse from sugarcane) would be helpful in India, Africa and South America.
But what if we could propel an airship without any sort of fuel? I will look at exotic propulsion systems in part 4.
****
To be continued . . .
Heroes Rising
Written by Kristine Kathryn Rusch
I found out about the shooting in the midnight showing of The Dark Knight Rises about twelve hours after it happened. I overheard someone mention it on the local radio station, so I logged onto a news website, saw the story, and burst into tears.
Mass shootings are tragic, period, and some have touched my life in ways more personal than this: a friend lost his son in Virginia Tech, and I knew lots and lots of people connected to the Springfield, Oregon, school shooting more than a decade ago.
But this one struck me in the heart in an entirely different fashion. Movie theaters are places we go to escape our problems. And one of my biggest escapes has always been Batman. Of all the superheroes, he is—and probably always will be—my favorite. I remember reading Batman comics when I started reading. I had a crush on my decade-older cousin, not because he was handsome (he was) or because he was witty (he was) or because he was nice (he was), but because he gave me a book-length collection of Batman comics when I was seven. I still have that collection. I read and reread that book.
I scarfed up Batman comics like they were going out of style. I even remembered the cliff-hanger ending of one series for more than twenty years. Long after I had met Julius Schwartz, who ran DC Comics during my childhood years, I asked him how that cliff-hanger ended. I’m sure Julie didn’t remember, but he said, “Robin survived,” and that was all I needed to hear.
I had already been thinking about heroes when this summer’s crop of bestselling novels appeared. I read a few in June, and realized that most of the characters in these rather dispiriting novels were trapped in ugly lives, and let events happen to them. Between those books and a somewhat depressing run of Mad Men episodes, I realized just how much I expect my fictional counterparts to take action—even if they have no idea what the outcome to that action will be. I want characters who try to be heroes, rather than those who believe that heroes do not and cannot exist.
So the week after the horrible shootings, I read a box office report about declining theater attendance. One teenage boy who had looked forward to The Dark Knight Rises for almost a year decided not to go because the shootings confused him. A group of kids on our local NBC-affiliate spoke in short sound bites about the tragedy.
One little boy said it was clear to him now that there was true evil in the world, true villains, but there are no real heroes. Not like Batman.
I wanted to tell him how wrong he was. I wanted to point out how true heroics isn’t about donning a rubber suit and jumping off buildings or driving around in cool cars. It was about shielding the person next to you, a person you don’t know, with your own body so that she can escape. It was about driving an ambulance through crowded streets, carrying stretchers into carnage, placing bandages on the wounded.
It was about holding a door so that others could escape, even as the bad guy came at you with his semi-automatic weapon.
It was a brief moment of action in an unspeakable situation.
It doesn’t take courage to walk into a crowded place with a loaded gun. It takes a great deal of courage to remain in that crowded place with the wounded and dying to try to stop the person with that gun.
There were a lot of heroics that night. They just weren’t flashy heroics. They were simple ones, the ones that mean the difference between life and death. I wish I could tell the kid that.
But heroics like that, those small but extremely important things, are hard to see, especially if you’re not looking.
About two weeks after the shooting, I went to see The Dark Knight Rises. I’d be lying if I said I didn’t think about the shooting, but not in the way you think. Yes, I thought about the wounded and the dead, about the difficulty some moviegoers had on that night in telling what was real and what was fake in those precious few seconds.
But mostly, I thought about the actual meaning of Batman’s heroics. In the film, the villain Bane effectively neutralizes Batman for months. Batman cannot save his city; he can barely save himself.
The people in Gotham are left to survive. A small group finds heroism inside themselves as they struggle against unimaginable evil. They exhibit, in a fictional way, the kind of heroism real people showed in that Colorado theater in July.
The Dark Knight Rises is about the importance of heroism and also about the importance of the little guy. In Batman’s absence, others step
up. They might not be as talented or as smart or as rich as Bruce Wayne. They might not have the resources—both physical and mental—that he has. That’s what makes him a superhero. But they do their part.
And the movie makes us see that part.
I’d love to find that kid who lost his belief in heroes that night, and show him the real live people who are every day heroes. But I also want to show him that the best stories we tell, like The Dark Knight Rises, are about the heroes hidden inside us. Heroes we don’t discover unless we’re in the middle of something awful and traumatic and impossibly difficult.
Individually, we cannot be Batman. He’s a fictional construct, and the scars Bruce Wayne has on his body are minimal compared to the ones a real human would suffer in his stead.
But collectively, we are Batman and Superman and Spider-Man and all of those superheroes who protect the worlds of our imagination. Batman can’t—and doesn’t—save everyone in every single story. None of us can save everyone. But we can—and do—save more people than we lose. We work together to repair that hole in the universe the crazies with guns leave behind them.
We do the best we can, and what we can do is pretty damn startling, every single time.
****
Eavesdropping at the Keyhole to Forever
Written by Ronald D. Ferguson
"What'd ya hear, Doc?"
"Just you, asshole. Give me a break." I didn't mind that the hulking Jenkins called me Doc instead of Doctor Meyers—well, not much—but that was the third time in the last ten minutes that he had interrupted to ask what I heard. Irritation thinned my lips, however I refused to look up from the Mozart processor. I fine-tuned another mic input. "I'm trying to sort this out. You aren't helping."
"Do you think they suspect someone is listening?" He popped another jelly bean.
"Would you shut up? Of course they suspect. They squelched most of the mics we planted. They've got the band playing full tilt with a mob of people chattering away for cover. You don't have a conference under those conditions unless you're worried about listeners. Have you got an aspirin? My head's throbbing."
"Sure, Doc." Jenkins fumbled in his jacket pocket. "Uh, how about acetaminophen instead?"
Jenkins might be an oaf, but he never stumbled over any drug name.
I nodded and selected two of the proffered tablets from his meaty hands. Generic? Why not? Since the University declined to renew my contract, my whole life felt generic. My mouth was dry, but I choked down the tablets without water. Vodka would have been better. How did the Mozart program handle discrete Fourier transforms without a stiff drink?
Jenkins patted the processor. "Nothing out of Mozart so far, huh?"
"If I feed this noise to Mozart without labeling the melody instruments, it'll take a week of processing to sort what you want from all the conversations, and that includes the band. We'd get a complete orchestration for the music."
"Music? Melody instruments? Alls we need is what Mr. Kelso tells Big Louie. Mr. Thompson ain't gonna want no musical arrangements. That ain't why he hired you."
"I know why he hired me—industrial espionage. One more setting . . . got it. We can separate and process all the recorded noise later, but for now Mozart will tease out the tagged tunes." I linked the last voice sample to the parse criteria, slapped the Mozart go icon, and leaned back to massage my forehead. I glanced at Jenkins's puzzled face. "Tunes. Counterpoint conversation. Mozart will extract the, um, decompose the labeled noise into the conversations you want."
Jenkins flashed a lopsided smile that exaggerated his deviated septum—or was it a broken nose. He popped a jelly bean and slapped my shoulder. My headache went migraine. My ears rang, and a halo of light distorted my vision.
"Uh . . . Can you get me something with lots of caffeine?"
"Sure, Doc." Jenkins searched through his pockets. "Whatever you want. Mr. Thompson told me to take good care of you. Nope, no caffeine tablets. Say, I've got some oxycodone, if that will help."
****
Most of the extracted conversation between Kelso and Big Louie was about eliminating competition from a start-up called the Garza Brothers and made little sense to me, but Thompson seemed pleased with my efforts. Two days after the transcription, Jenkins paid me ten thousand in cash and suggested Thompson might have more work for me the following week. That was better pay than I had expected for a few days work—better than a tenured teacher takes home in two months—so I kept Mozart processing the recorded cacophony from the party just in case Thompson wanted more details. I had worked four years developing the Mozart technology, and with my academic career at an end, this was my best opportunity to make it pay.
While Mozart cranked away, I counted my cash at the kitchen table and wondered whether I could get back my old apartment—the new place was a dump.
The phone rang.
"Meyers here."
"Wally?"
Only one person called me Wally. "How did you find me, Christine?" I had expected to hear from her, but not so soon. Was I ready? Damn my weak backbone. Of course, I was ready. I could never resist her, and eventually, I would have called.
"Google, of course." Her giggle sounded forced, artificial. "Are you still angry?"
"I'm not angry, Christine." Best to take the high road rather than sound angry or grovel. After what she had done, taking the high road could only make her feel worse. So, I claimed the blame. "The whole thing was my fault."
Not true. Well, not completely true. Sure, I'd looked at another girl—geez, every guy looks—but I hadn't made any move, not unless you consider a smile and a pleasant hello a move: something I had never done before Christine. Hell, I hadn't the confidence to make the first move for my entire life. Not even with Christine. What would a girl like that be doing with a geek like me? Despite my excuses, she was persistent. Three times she suggested we go out before I lost sight of the student-teacher boundary.
After we were a couple, Christine did not become a jealous lunatic overnight. Not until—what was the girl's name?—smiled back at me. Insecurity? Perhaps with her as a twenty-two year old new graduate student and me as a six years older prof . . . Naw, that wasn't a big age difference. I should have apologized and sent her flowers, but who would expect a level-headed girl like Christine suddenly to run to the dean in a jealous rage. She reported me for an affair with a student—in this case, she was the student. I couldn't deny the charge, and that was the end of my wunderkind career. Defense? What was I going to do, publicly call the girl of my dreams a lying bitch?
"I miss you," she said.
Nice serve, just inside the center court line, but now I knew how to play this game. I backhanded. "Good to know."
She couldn't get me fired again, but she needed to learn to think before acting. I should have done the same before I let her talk me into that first date. What was I thinking? I wanted to be with her the first moment I saw her. How did I hold out until the third invitation?
I let the silence extend.
"Well, my number hasn't changed." She took a defensive position.
"You've already got my new number. Take care, Christine." Smiling, I hung up before she could respond. New game, first point to me. I would grow a backbone yet.
****
Jenkins brought me a recording on the following Monday.
"Mr. Thompson wants to know if you can make anything out of this. He had a high-gain recorder in his pocket at the mayor's weekend party."
"What's he looking for?"
The mayor's party? Politics or contract bids? Snooping on public contracts up for bid made me more uncomfortable than industrial espionage.
"He don't know. Separate it out and see what you find."
"Sure." I checked the length of the recording. "Any idea how many distinct voices?"
"Small party. No more than a hundred people. You want a jelly bean?"
"No, thanks. Without some target voice samples, this could take a couple of weeks. Most conversations at a
party have little semantic content, but you don't know that until you wade through them."
"I don't know nothing about semantics, but Mr. Thompson will make it worth your while. How about twenty big ones? Say did you see the news? Mr. Kelso had a fatal accident last night. Same kind of accident that killed the younger Garza brother."
"Mr. Kelso?" I suppressed a chill and pretended I didn't remember the subject of my previous eavesdrop. I had seen the news about Garza a few nights before, but hadn't connected that death to the startup company that Kelso wanted out of the way. What kind of business had Kelso run? What kind of business gets you killed? What was Thompson's interest?
"Kelso. Just a rival of the boss." Jenkins shrugged without breaking his smile. "No one important."
****
While Mozart digested the recording from the mayor's party, I reviewed the remainder of the output transcription of the Kelso data, searching for anything that could ease my apprehension. Once in analysis mode, I focused on stats for the data output. Despite the fact that I wrote the program, the decomposition statistics impressed me. Mozart had distinguished seventy-three distinctive voices. Eight were band instruments, three were barking dogs, sixty-one were people, and one was unknown.
The orchestration for the band looked pretty good. Marked as a separate conversation, Mozart had converted the songs to sheet music where each instrument voice had its own line. In a quick examination, I saw no outstanding orchestration errors. That didn't surprise me. Mozart made fewer than five percent errors when transcribing small bands. However, Mozart had included the dog barks as part of the musical score—too avant garde for my taste.
Although I had already given Mr. Thompson the extracted conversation between Kelso and Big Louie, I reviewed it again. With Garza and Kelso recently dead, seemingly innocent comments took on an ominous tone. Hoping I was wrong, I scanned the other conversations for support. The more I read and re-read, the more it sounded as if Kelso had subtly ordered Big Louie to kill the younger Garza, but who had ordered Kelso's death? The elder Garza brother in retaliation? Surely, not Thompson: I couldn't have involved myself in a murder.