Solid Booster Revisited

I had previously proposed a deep space propulsion system. I improved the design so that it can be used both on the first and the second stages of a rocket as well.

The solid booster would be composed of three sections.

The booster section where the solid propellent is burned and the thrust is generated. This section needs to withstand high temperature and pressure.

The transfer section where the stacked solid propellant is transferred to the booster section. This section should have enough opening to allow the booster section doors to open. This section needs to withstand moderately high temperatures and pressures because the new propellant block needs to be transferred to the booster section while it is still hot and has some pressure.

The storage section where the stacked propellant is stored. This section has no particular temperature and pressure requirement.

The solid booster will fire when the storage section is full and the booster section is loaded with a propellant block. Once the solid propellant inside the booster section is consumed, the booster section doors will open. Then the release latch will be opened to release a propellant block into the booster section. After that the booster section doors will close and the rocket will be fired once more. Finally, the release latch will be closed and the holder latch will be opened to allow the remaining blocks to slide down.

The solid propellant blocks will be molded inside a plastic shell like HDPE. This will allow them to slide down more easily and prevent cracks to the solid blocks. HDPE burns out completely into carbon dioxide and water vapor which would contribute to thrust as well. The solid blocks will have different grain geometries and height to suit to the thrust need. The initially fired block will be optimized for high peak thrust and short burn time to allow takeoff. As the rocket gets lighter, the grain geometry will allow more burn time and lower peak thrust.

The solid boosters require strong shells that are heavy. By shrinking the booster section, the weight saving would be high. Additionally, as the propellent is consumed inside the booster, the thrust goes down due to increased combustion volume due to the void of the consumed fuel. Burning propellant in sections and keeping the combustion volume small increases the efficiency of the rocket.