Affectionately known as GAR-E (“Gary”), this engine system shares nearly all the same propellant, control, and testing infrastructure as Borealis. This means it’s also an EthaNOS engine, using a nitrogen pressure feed system. The very first iteration of GAR-E also shares the same combustion geometry as Borealis.

Where GAR-E differs is its construction and use case, made of a Garolite chamber and nozzle inside a reusable aluminum casing. Garolite is a fiberglass-reinforced laminate composite material used in a variety of applications. GAR-E uses this, specifically FR-4, for the combustion chamber and nozzle. Garolite is an excellent silica phenolic ablative, a family of materials with extensive flight heritage and use in rocket engines. Most importantly, FR-4 is extremely economical and machineable, allowing us to test different chamber geometries and easily upscale our designs.

While the first iteration of GAR-E will perform identically to Borealis, the goal of the GAR-E family is a larger 1500 lbf thrust engine of the same overall design. This is our performance target for the flightweight engine, which will use the same combustion geometry validated by GAR-E, with higher-performance materials and an even lighter construction. Larger SRAD propellant tanks to support the high-thrust engine are also under development, giving us experience in advanced manufacturing techniques for flightweight structural tanks.