Skyhooks and spacecraft

I've got a couple of new doodles today, mainly of two spacecraft as well as the rotovator I alluded to in some earlier posts. Let's look at the two spacecraft up close first!

These are two different vehicles drawn notionally to scale with each other, though they have a lot in common. Above we have the passenger tender, a smaller vehicle designed to ferry people to and from those big artificial gravity spaceliners. Below is a cargo freighter, with a much larger volume for shipping between worlds in the Rosa system.

Both of these spacecraft are powered by chemical rocket engines mounted in the back, with propellant stored fore and aft of a centrally located payload bay. In addition to some reaction control thrusters, both are equipped with some kind of metallic heat shield for atmospheric entry. Both reenter skydive-style, pancaking into the atmosphere, stabilized by four drag flaps (two of which are fixed). Finally, to accommodate the unique terrain and infrastructure available in the Rosa system, both vehicles deploy large inflatable lifting gas envelopes from dorsal compartments, arresting their descent until they become inert aerostats that can be manipulated by other vehicles.

Critically, these weirdos are both air-launched, in a way, although here we see some major operational differences. The passenger tender is air-launched "conventionally" as we might think of it today: carried beneath an aircraft (albeit a large airship rather than a fixed-wing aerodyne), dropped, and powered into space by its own propulsion. The tender must accelerate all the way up to escape velocity during this burn, which is made easier by the relatively small mass of the worlds in this system. As previously described, the tender can then rendezvous and dock with the spaceliners, which will hold them in transit before releasing them to perform atmospheric entry.

The freighters are a bit weirder, being integrated with the skyhook system; I've already talked about this, but due to generally lower g-limits for cargo compared to crew, freighters are well-suited to getting yoinked into space by the enormous sky pinwheel. Doing some preliminary math implies this could easily put them on interworld trajectories, so they could potentially use even more of their volume for cargo, with very little dedicated to propulsion at all - cool! That said, the scaled-up tender version with its vast fuel tanks and engines is still used quite a bit since the skyhook/rotavator/spintowininator (note to self: name it properly) is only available when travelling from Orus to another destination.

Here's some more sketches of these dudes:

Notice the much wider planform of the freighter and its beefier engine section (only present on some models!). At bottom-center is a depiction of the freighter exchange process: three hybrid cargo carrier airships have aligned in formation, each carrying three freighters in a line down its back. Arriving in sync with a rotovator endpoint, all 9 spacecraft are lifted off the decks and begin the long climb to escape...at lower left is an exaggerated depiction of the multi-armed rotovator concept I've been thinking about, with six separate endpoints. At the top of their arc the spacecraft all separate at once, firing RCS in an enormous plume to disperse from each other, the grid formation uniformly expanding as the tether curves away beneath them.

Finally, here's a dramatic angle of the rotovator hub as it orbits languidly above Orus. The center is probably a command station home to a team of traffic controllers, working overtime to keep this mega-infrastructure (infra-megastructure?) running smoothly.

One of these days I want to model both spacecraft, perhaps in Solidworks so I can try for pretty accurate geometry. But that's a project for another time. That's all for today!