We have been using the same propellant system for rockets since before 1000 A.D. with volleys of bo hiya at the siege of Yuzhan.
While bamboo works well enough to generate force from expanding gases, they have never passed the flash and weapon stage. Yet, with enough gas and fire in a tube, you can break the gravitational hold of the earth.
From gunpowder to liquid propellants to solid rocket boosters and a few trials of nuclear fuel, only size, volume, and chemistry has changed for over a thousand years.
We propose a new paradigm using old methods: Keep the chemistry, drop the booster, hide the nuclear fuel and add a balloon/solar sail.
LiftShips™ (pat. pend.)
Use a Hydrogen balloon for the initial launch.
At the apex, the Hydrogen is compressed, pumped out to nozzles, combined with Oxygen and ignited to
push the LiftShip™ just high enough to use the depleted balloon as a solar sail.
Of course, new materials can be developed for a balloon with high burst resistance and characteristics necessary to convert to a solar sail.
Propulsion systems such as nuclear, ion engines and solar sails are all options once the gravity bonds of earth have been broken, but are not viable as launch systems. Other launch options such as magnetic rail guns or space elevators are possible, but haven’t been developed yet.
It takes energy to get lift and higher energy systems generate more lift, but as you move up the periodic table, you have waste products that are toxic downstream from the output.
Our popular fantasy TV and movies all have some unspecified, powerful propulsion system that can easily break our gravity well to send us to outer space, none of them are available today and are still fantasy in our world.
Sure, Dilithium crystals are wonderful and the “boop-boop-boop” of the Jetson’s car are bound to be a huge source of cheap, safe, unlimited power, someday, in some future time, maybe.
We have the materials available now to bring cheap, effective access to space for humans who aren’t rich or lucky.
Hydrogen, Helium and Methane are molecules which are lighter than air, although only Hydrogen and Helium are typically used to lift objects in our atmosphere over the at least the last 200 years.
You can float to a neutral point in the sky using any of the gases, with some obvious limitations; When the atmospheric pressure is decreased below the tensile strength of the shell, the balloon bursts and the device plummets to earth.
With a few modifications, such as nano-particle bonded fabric, we can take a balloon system to the next level:
Use Hydrogen for lift (careful, explosive), to take the system to the upper atmospheric reaches.
When the balloon ascent stops, pump in oxygen (from on-board cylinders), simultaneously pumping down the hydrogen and fire off a small rocket engine.
After the engine boost, the empty shell can be pulled around an internal framework as a solar sail for additional lift.
Of course, this is a radical, untested system, but if it works, it could open up space flight to the rest of the world and we can start finding the hyper-sonic Dilithium crystals our movies tell us will replace all other propulsion systems.