Designed and validated two coaxial sleeve valves for use on Waterloo Rocketry's 2026 Rocket, Polaris. Increased flow rate through the injector valves by 40% will reducing mass by 60% and simultaneously reducing footprint. Performed stress analysis to ensure reliable operation for fluid pressures up to 800 psi. Performed force balance calculations in order to ensure reliable sealing and opening of both valves at various working pressures. Developed test procedure to characterize pressure drop across coaxial sleeve valves and used the data to inform valve sizing. Validated the valves through high pressure hydrostatic and pneumostatic testing.