One of the first test engines has been assembled today and is being tested before a hot fire. In this process we've been learning a lot about designing for manufacturability and cost with larger, future propulsion systems in mind.

One of our main concerns was with the high temperature seals between the combustion chamber and the injector plate, which was required for modularity, and the dissimilar materials used in the construction of the engine which might reduce the efficacy of the seals further under extreme temperature differentials. Some initial testing indicated that our designs were adequate but we will find out during the full-on test. 

In the end, the engine weighed just under a kilogram. Even though it was never designed for flight, we still had a pretty good thrust-to-weight ratio of 25:1.