Low-tech space entry vehicle (no space elevator mountains needed)

Build two giant airships – lash them together like a tri marine with a central platform suspended between them – build a big catapult & bolt it to the centre platform

Of course when I say ‘catapult’ I’m really thinking of some kind of faux rail gun powered by stored kinetic energy, probably compressed air (so a giant air rifle)

You're using a traditional airship design with a gas compressor to reduce lift (works a bit like a fishes swim bladder)

This puppies going to be big so we don’t want it going hindenburg on us which means we’re probably using helium – which means for the same lift it needs to be a whole lot bigger than the hindenburg, besides which we want a lot more lift than that anyway as conservatively speaking it needs to get something as heavy as a half size space shuttle as high as you can go & then has to have enough lift to absorb the downward thrust of the catapult without losing altitude (causing a loss of upward thrust from the catapult)

Hmmm – hydrogen will get you higher than helium anyway won’t it – maybe we’ll just have to risk it

What was that guy who did the high altitude parachute jump using in his balloon?

Once you reach maximum altitude you use the catapult to launch your shuttle toward space & it ignites its engines at the zenith of the arc thus imparted

The airship returns to earth by compressing some of its gas to lose lift – probably using solar panel powered electric motors (the whole point is to cut back the fuel requirements necessary to achieve escape velocity as much as possible after all) to pick up a new payload (a fresh shuttle) & get the catapult reset

Anyone know precisely how close to space you can get with hydrogen & helium balloons respectively?

Hopefully we can get high enough to launch small payloads to escape velocity with a big catapult alone if we design it with modern materials & engineering

As for re-entry, I’d hope for something with sufficient wingspan to weight ratio for un-powered gliding once it reaches adequate air density (of course a wingspan like that wouldn’t survive traditional re-entry so they probably need to be retractable) though it might be nice to have a small onboard atmosphere engine for powered flight if needed (an electric solar power / alcohol fuel hybrid engine maybe with a propeller or air turbine perhaps – we could even have the air turbine reversible so it generates power from the airflow in the early stage of decent after it’s re-entered the atmosphere which can be used to power it when it reaches lower altitudes)