Solid Rocket Motors for High Performance Interceptors

Corvid Technologies, in partnership with Aerojet-Rocketdyne, proposes the development of a highly loaded grain (HLG) rocket motor that will exceed the total impulse of the current baseline motor by a minimum of 20%. To achieve this, Corvid will first define a baseline rocket motor that is consistent with current available technologies. Next, Corvid will develop an advanced nozzle concept to improve efficiency throughout the flight profile and allow the propellant combustion chamber to be expanded. Corvid will then develop an innovative three-dimensional, functionally-graded propellant grain for the HLG rocket motor, leveraging high burn-rate, high specific-impulse propellants to achieve the desired burn-rate and surface regression profile while maximizing propellant mass within the grain. In order to improve technology readiness level (TRL), Insensitive Munitions (IM) requirements will be considered for these propellants. A comprehensive performance assessment will be conducted to compare the HLG rocket motor with the enhancing technologies against the baseline rocket motor configuration to determine if solicitation objectives have been achieved. The proposed AED nozzle is a refinement of the Expansion-Deflection (ED) nozzle originally developed and investigated in the 1960s through 1990s at Rocketdyne (now Aerojet-Rocketdyne). ED nozzles compensate for altitude and are substantially shorter than comparable internal-flow nozzles, allowing for more propellant in space-constrained motor designs. Historically, the challenges of designing ED nozzles have been cooling and structurally supporting the central plug to reduce ablation and prevent structural failure. The AED nozzle will use modern refractory metals, shape memory alloys (SMA), and additive manufacturing processes to structurally support the plug, eliminate the need for active cooling, and allow the shape to adapt over time to compensate for ablation and provide more optimal performance over a range of altitudes. Achieving adequate performance over the flight profile is challenging with HLG propellant grains. This is due to the reduced initial surface area available for burning and the patterns in which the surface regresses. Furthermore, complex grain geometries are often required to regulate burn rates and surface regression, resulting in risk of the structural integrity of the grain or a part of the grain being compromised during the burn. To achieve high loading and mitigate the risks, Corvid will focus on two methods of regulating burn rates and surface regression in order to achieve this technical objective: Functional grading of the propellant constituents throughout the grain Slot perforations at the grain base as necessary to reach operational pressure and optimize burn rates These two methods provide flexibility to achieve acceptable burn rates and chamber pressures of the intended flight profile while maintaining structural integrity of the grain. Approved for Public Release | 20-MDA-10643 (3 Dec 20)