...And We Will Have Snow

Chapter 5-10: Going Ballistic

They stayed in the alcove for quite a while. Bear and Newt had lots of questions about what it was like flying the drone across the country the way she had done. Dema and Cern remained quietly attentive, very interested in the World Dream idea and the way it was coming together. But when they felt all caught up and the boys still had questions, they begged off, said their goodbyes to Sedna, and went back to the dome.

When the questions from Bear and Newt finally began to wind down, and started to morph into a discussion of possibilities between the two of them, Sedna mentioned how long she was thinking it would take her to return from Houston to Seattle. "Probably hours and hours," she said.

Newt said, "Why don't you go ballistic?"

"I admit it's a bother, but I'm not really angry about it."

"No, I mean sub-orbital flight. Any flight over 500 miles can be faster if you go up and down. It's the reason no one is building longer Hyperloops."

"Huh? How's that?"

"You know how Hyperloops work, right? They can go fast because they run in a partial vacuum, with reduced air friction."

"Yeah, I guess."

"But it's only about a hundred miles up to get out of the atmosphere. Then you can go as fast as you want to the place you want to come down again. It's the first thing you learn in rocket school."

"I've never been to rocket school."

"Ready for Rockets 101?"

"O-kay..." Sedna was a bit noncommittal.

"The hard part is going a hundred miles straight up. But you can already do that. Once you get there, it's just a matter of how fast you can get to where you want to come down again."

"But you said 'ballistic.' That sounds like a hard landing."

"Yeah, that's more the cannonball model. The point of that is really that coming down is pretty much the reverse of going up, and that's true for powered flight."

"The rocket principle?"

"Exactly. You're flying a rocket. So you can do it all more gently."

"All that's pretty obvious. Where does Rockets 101 come in?"

"There's an optimum path. You could fly low to stay out of sight, hugging the terrain, but then you're limited by air friction. You could fly high, and go as fast as you like, with straight up and down takeoff and landing legs. But those legs add to the total distance you have to go. The optimum path is somewhere in between, including some horizontal travel in the up and down legs. Rockets 101 is about figuring out that optimum path."

"More like the cannonball path."

"Without the high-g start and stop. How many g's can your drone take?"

"I have no idea, but probably a lot."

"How about temperature?"

"What's the flash point of carbon fiber? Fahrenheit 451?"

"Ha ha, you're a Bradbury fan. That's what he said was the flash point of paper, a carbon compound. Pure carbon ignites and burns at a much higher temperature. Not much to worry about if you take it easy."

Bear said, "So what's the fastest way for Sis to get home?"

Newt said, "Well, let's think it through. She's not worried about running out of fuel, so she could just go straight up and hover. But that doesn't get her home. So let's say she takes a curved path, going straight up at first to get out of the lower atmosphere but curves over so she's going horizontal by the time she's a hundred miles up."

He pulled his PDA out of his pocket and started talking to it. Bear and Sedna heard him saying things like "hundred mile radius," "orbital velocity" and "two thousand miles." Then he looked at Sedna. "You can be home in about ten minutes."

"Ten minutes?"

"Well, eight really. Counting a minute up and a minute down. But it was a rough calculation."

Bear was looking as astonished as Sedna.

"I can have the drone home in time for dinner! I could visit you half a dozen times a day if I wanted to!" She raised her arms as if she wanted to give Newt a hug, then she thought better of it. "I could hug you," she said, "But you wouldn't want to be hugged by a drone."

Newt said, "Bring it on!" and she grinned at him, but didn't do the hug.

"This thing is stronger than it looks," she said, "And not nearly as soft as I am."

Newt pretended to be disappointed. He didn't have to pretend very hard.