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Completed TRL 1 (started at 1, targeting 3)
The primary objective of this program is to develop a low-cost engine for use on spacecraft. The target price for commercially available engines at production rates is $100,000 per engine. Additional objectives are to meet 300 seconds of specific impulse (Isp) in a lightweight package. The main requirement is to be in the 100 pound-thrust class, which means, in this case, a thrust level between approximately 100 to 150 pounds. The propellants used will be monomethyl hydrazine (MMH) and mixed oxides of nitrogen (MON). The engine will be designed to the desired MON level, which can vary between MON3 and MON30. The engine can potentially be designed for use with multiple MON levels. This engine must also be of sufficient size, weight, and performance suitable for use on spacecraft. This engine will be based on an injector designed and developed by FAC on IR&D.
At the conclusion of this program, FAC will deliver two prototype engines that meet the design criteria, a technical report that includes analysis showing that the engine can be tested successfully, and a cost estimate showing that production engines can be made commercially available at the $100k price point. This work will be performed with the support of NASA MSFC, utilizing MSFC’s expertise in analysis and manufacturing.
The objective of this program is to develop low-cost in-space bi-propellant engines. This objective will be met by developing and manufacturing two prototype engines. The design will be driven by the need to minimize production costs. The design process will be documented with supporting evidence to indicate the performance and stability of the engines. These engines will be assembled and delivered ready for test at the completion of the program.
The technical approach to these engines is a departure from what is currently commercially available because they are designed for use on a variety of systems, not for a specific system. These engines will be available individually and not as part of a system. FAC is unaware of competing engines that can meet this low price point. The program begins with a kick-off meeting at FAC, which is the first milestone. This is followed by the order of long lead material and hardware. This includes cartridge-type solenoid valves, Teflon-coated spring energized seals, and niobium C-103 powder/bar for the thrust chamber. C-103 powder is used for development and build of additive manufactured (AM) chambers. C-103 bar will be a backup for machining of chambers, if necessary. Two valves are used per engine which allows individual control of fuel and oxidizer timing. FAC has two valve designs that are correctly sized for this engine, which will contribute to initial design maturity.
These valve designs meet the necessary flow rates. Valves and chamber material are the primary long lead items, which will take up to 5 months to receive. Orders from these suppliers will have weekly meetings with the supplier until products are received. This is to ensure adherence to the planned schedule. Technical and status meetings with MSFC are anticipated every two weeks throughout the course of the program. Immediately following the order of long lead parts, design of the engine will take place. This includes reuse of an FAC internally developed injector. Rough initial sizing calculations will take place to determine desired sizing. The design effort is for a workhorse style engine with a bolted (not a welded) chamber and injector. The engine design is based on an engine currently in development known as the Deep Space Engine (DSE) axial, which uses a FAC internally developed injector.
The combustion chamber will be based on existing FAC designs and will target 300 seconds Isp. With the final design selected, detailed performance analysis will commence. Start-up, transient, and steady-state performance will be predicted based on in-house software tools. This is to ensure meeting the requirement of stable combustion with 300 seconds Isp. NASA MSFC will support FAC by analyzing the injector manifold. This analysis will be reviewed with FAC. MSFC will then design a new manifold with improvements to the flow passages for additive manufacturing using MSFC tool results and expertise.
Following analysis will be a FAC internal design and manufacturing review, a major milestone, held at FAC. Detailed drawings of parts, assemblies, and tooling will be in work during analysis and mostly complete by the review. Upon successful completion of this review, manufacturing of parts will begin.
The parts that will be manufactured include the injector faceplate, injector body, acoustic cavity ring, combustion chamber, valve housing, and valve nut. Enough parts will be made for two thrusters, including some spares. Both a machined injector and an additive injector will be manufactured, one for each engine. MSFC will produce the additive manufactured injector. The AM injector will be final machined and EDM drilled as a final operation. The combustion chambers are planned to be made using additive manufacturing machines with niobium C-103 powder. If additive manufacturing is not possible due to schedule or availability, chambers will be manufactured with conventional machines.
The receipt of all hardware, excluding the MSFC provided AM injector, is a major milestone. It allows engine processing to continue, which is almost entirely performed locally. Once chamber manufacturing is completed, both chambers will have a silicide coating applied. All parts will be inspected for quality verification. The faceplate will be EDM drilled and inspected at a different location following initial machining.
The machined injector body, faceplate, and ring will be cleaned, prepared, and assembled into FAC internally designed tooling for the diffusion bonding process. This process fuses the material together so that it performs similar to wrought material. After diffusion bonding, helium leak check is performed for bond verification. Final machining is then performed on the bonded injector, followed by cleaning. The final assembly step is assembly of the bonded injector, thrust chamber, valve body, and valves. The final assembly is leak checked again. At this point, the engines are ready for testing and will be delivered to NASA MSFC. This marks another major milestone. Finally, a project report is composed documenting the design and manufacturing processes. This includes stability and performance predictions. Completion and delivery of the report is another milestone. The program concludes with a closeout meeting, the final milestone.
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