“The area with the pipes and valves and their actuators and electrical runs must have a door!”
“I’m sure there’s a door,” Lee said. “We probably just didn’t notice it when we scrolled through.”
“No,” Kaem said, “There’s not. Besides, unless they’re planning to use very small people for the final assembly, they need two doors since the opening from one side of the plumbing chamber to the other is too small for normal-sized adults to squeeze through. Using Stade, they don’t have to worry about doors weakening the structure and a little design work should keep it from obstructing the outer airflow.”
“Next. I’d suggest they have us cast all their valves and piping and other small components in air-density Stade, not vacuum-density. That way they can assemble and weld them together with the pieces floating in the air and easy to handle. They won’t have to fight to keep them from shooting up to the ceiling. Admittedly, we’ve all learned to work with components that’re trying to fall to the floor, but humans have a lot of experience with gravity and we can reach the floor to get stuff we’ve dropped. If they’re going to assemble small, vacuum-density Stade components, they need to have an assembly room with a low enough ceiling that their workers can reach things that got away without getting a ladder.
“Another suggestion would be to cast the rocket body as a hinged clamshell. Then they can hang it over the assembly area and put major components like the engine block and plumbing block and tanks into one half of the opened clamshell. Once everything’s in there and welded together, they weld it to one side of the clam, then they close the clam and weld that. Voila, you’ve got a first stage rocket.”
He leaned back. “Any other issues you’d like me to look at?” When Kaem looked at her, he saw she’d been recording a video of his comments. Seemed smart, though Kaem didn’t have a feel for what it was like to not be able to remember things that were important.
Lee said, “Let me go over this some more. I may have some questions before I send our comments to Space-Gen.” She hesitated, then brought another window up on the screen. “Could you look at this for me?”
Kaem looked at it, “What is it?”
“It’s a run at a joint to hold together the sections of the space tower. I’m trying for something like a Morse taper so we’ll have a rigid fit.”
Kaem frowned, “What’s a Morse taper?”
“It’s a very shallow angled cone. You jam a male tapered cone into a female socket with the same taper and, with metal and the right angle, they wedge together and stick solidly together. Of course, with frictionless Stade, they’ll slip back apart, but if we force them together and hold them there, they’ll lock in without any jiggle at the joint. I’m thinking we’ll have to have some kind of threaded mechanism to keep them squeezed together.”
Kaem indicated her trackball, “Again?”
She nodded.
He took over the trackball and started rotating her drawing to see it from all angles. “You’re planning enclosed tubes?”
“Uh-huh. With rails on the outside that’d let us slide on additional parallel tubes when we have more traffic,” Lee said.
“I was picturing an open framework. Why are you going with enclosed tubes?”
“So we can evacuate them to reduce wind resistance to high-velocity launches.”
Kaem tilted his head, “It’s going to take a lot of energy to evacuate the tube. Are you sure you’ll save energy over the cost of forcing the craft up against air resistance? Especially considering that your launch will be moving slower down where the atmosphere is dense but that you’re going to have to evacuate the tube up to a pretty high altitude, then suddenly open a door when your vehicle reaches the upper end?”
“You’re thinking an open framework will allow the displaced air a way to escape?”
He nodded, “A really open framework. There’d be the launch rail with nothing around it.”
Looking appalled, Lee said, “But, at least down low we need to keep it all clean. Keep the bird crap off of it, and—”
Kaem interrupted, “It’s Stade, Lee. If birds try to perch on it, they’ll slide off. If they manage to crap on it anyway, that’ll slide off.”
She shook her head, “I’m thinking of the electromagnetic rails that are going to do the launching. We can’t have birds crap on them.”
“Oh,” Kaem said feeling a little surprised. “I guess we haven’t talked since I gave this more thought. We’ve always got to consider how to use the advantages Stade gives us. One of the advantages of the various linear motors is their ability to levitate the load off the rails to reduce friction. Since Stade’s frictionless, we don’t need that. Hundreds of kilometers of EM rails would add a lot of mass to your space elevator. Linear motors work as if you’d taken a rotational electric motor and unrolled it. If we think of it that way, instead of having one set of coils running around the circumference of a rotating motor, you’re going to have well over a hundred kilometers of linear motor. It’d be enormous! And massive.” He grinned, “And massively expensive.” He shrugged, “Besides, as you point out, birds crapping on that would cause a lot of problems.”
Lee narrowed her eyes. “Don’t tell me you’re going to use a rocket to push our spacecraft up the elevator! Why even have an elevator?”
“No, that’s not what I’m…” His eyes lost focus, “Though I would point out that
