The pressure-fed engine is a class of rocket engine designs. A separate gas supply, usually helium, pressurizes the propellant tanks to force fuel and oxidizer to the combustion chamber. To maintain adequate flow, the tank pressures must exceed the combustion chamber pressure.
Pressure fed engines have simple plumbing and lack complex and often unreliable turbopumps. A typical startup procedure begins with opening a valve, often a one-shot pyrotechnic device, to allow the pressurizing gas to flow through check valves into the propellant tanks. Then the propellant valves in the engine itself are opened. If the fuel and oxidizer are hypergolic, they burn on contact; non-hypergolic fuels require an igniter. Multiple burns can be conducted by merely opening and closing the propellant valves as needed, if the pressurization system also has activating valves. They can be operated electrically, or by gas pressure controlled by smaller electrically operated valves.
Care must be taken, especially during long burns, to avoid excessive cooling of the pressurizing gas due to adiabatic expansion. Cold helium won't liquify, but it could freeze a propellant, decrease tank pressures, or damage components not designed for low temperatures. The Apollo Lunar Module Descent Propulsion System was unusual in storing its helium in a supercritical but very cold state. It was warmed as it was withdrawn through a heat exchanger from the ambient temperature fuel.
Meth can be continuously produced in massive amounts in an automated closed system with very basic ingredients, Ammonia/Lithium for example are abundant throughout the universe. Not only does the synthesis of meth create a lot of energy, waste and gas, the vaporization and combustion of the drug creates a massive flow of endless supercharged vapors.
I think this principle could be used like some kind of tweeker gyroscope that constantly burns meth rocks at a rate of 1kg/minute and the energy produced from this infinite boiling puddle of meth vapors being re melted, smoked. THe meth fumes with push us across the universe.
The only thing missing is an oxidizer, maybe Ammonium nitrate? lolz.
