The Ultimate Sliding Rocket

I am improving on my collapsible rocket idea. I propose the use of encapsulated liquid acetylene as the fuel and liquid nitrous oxide as the oxidizer. The boiling point of acetylene is -84 °C and nitrous oxide is -88.5 °C. At -89 °C both are liquid. Both the fuel and the oxidizer will be stored inside Kevlar-Kapton bags. Both materials are strong at very low temperatures, flexible and light weight.

The second stage of the rocket would slide inside the first stage over the Teflon railings to minimize friction. The new design allows solid rocket casing with no deformation and aerodynamic change during flight. The liquid propellent would be squeezed out of the flexible bags. The weight of the second stage and the payload would provide the pressure needed for thrust. This design removes the need for complex turbo pumps, propellent cooling and pressurizing Helium tanks. The propellent remains liquid throughout the flight due to constant pressure and decreasing container volume.

The stage would be much lighter than a traditional rocket stage. All the fuel inside the stage can be burned. The reusability would be achieved by the Catcher in the Fly and the stage would slow down using the on-board parachute.

During stage separation the outer walls of the first stage would act like a barrel of a cannon which would repel the first stage (slowing it down) and transfer more forward momentum on the second stage compared to traditional rocket designs.

This design can also be used on the second stage as well. This time the payload would slide inside the second stage and provide the weight pressure on the propellent.