Laika

Plumbing and Instrumentation

The Laika plumbing system will need to be able to supply a steady oxidizer mass flow while being able to support repeated test fires of N2O. N2O is a non-toxic, non-corrosive, transparent, and odorless gas. It can be stored as a liquid with a density of 0.745 g/cm3 at 56 bar at room temperature, 20˚ C. Nitrous oxide exhibits a self-pressurizing behavior due to its high vapor pressure, which is an advantage for Laika’s plumbing system, and thus a blow-down plumbing system will be utilized.

In reference to the plumbing and instrumentation diagram. The main line will be 0.25” stainless steel piping and the N2O tank (Tk-N2O-001) will be a stainless-steel gas cylinder. The manual valve immediately after the N2O tank will ensure the tank can be disconnected from the main line and allow for service of downstream components. Following the manual valve (Mv-001) there is a regulator (Rg-001) that will control the downstream pressure immediately after it. 

Due to the self-pressurizing behavior of N2O, the tank will maintain a specific pressure based on the ambient temperature of the tank. Therefore, an onsite heat management solution may be required to ensure consistent output pressure. This pressure will fluctuate due to the ambient temperature outside the tank and cooling as the N2O leaves the tank, so the regulator will ensure that the oxidizer is supplied at a set pressure. The regulator (Rg-001) is subject to change or removal in future designs. 

Beyond the regulator, the main line will intersect with the vent line which will provide an access point for the solenoid actuated vent line valve (Sv-002) and the pressure relief valve (Pr-001), the vent line valve will give remote control over purging of the plumbing system and diverting the flow to vent from main line flow. The pressure relief valve will be set to a cracking pressure of 1500psi, this being 15% greater than our expected maximum operating pressure of 1275psi, and 500 psi greater than our line rating of 2000 psi. Next, the solenoid actuated main line valve (Sv-001) will be the main control over the flow of N2O. Following this is a check valve (Cv-001) that will prevent backflow of combustion gases from downstream. 

Just before the injector, there will be a pressure transducer to measure the pressure immediately before injection into the combustion chamber to ensure nominal pressure drops across the plumbing, as well as providing a pre-injector pressure for calculating change in pressure across the injector. The final connections to the manifold and injector will be a segment of flexible tubing to minimize effects of vibrations and movement of the engine on the plumbing.