Firefly Aerospace Completes Risk Reduction Testing for Critical Miranda Engine Components

Based on the company’s flight-proven Reaver engines, Miranda quickly scales to support Medium Launch Vehicle

Cedar Park, Texas, March 22, 2023 – Firefly Aerospace, Inc., an end-to-end space transportation company, recently completed risk reduction testing for critical Miranda engine components ahead of the first hot fire scheduled this summer. As a larger, scaled-up version of the company’s Reaver engines, Miranda will power the Medium Launch Vehicle (MLV) Firefly is co-developing with Northrop Grumman.

“We are making significant progress in the development of our Miranda engines that started less than a year ago,” said Bill Weber, CEO of Firefly Aerospace. “By leveraging our flight-proven engine architecture and our team’s propulsion expertise, we are conducting a hot fire test in just a few months.”

The risk reduction testing was successfully completed for Miranda’s main fuel valve and the throttle valve hot seal design. The hot seal was tested several times during routine Reaver engine hot fires. Due to the commonalty of Firefly’s engine designs, the team can conduct robust flight-like testing and validate performance for both Alpha and MLV.

“We built prototypes and successfully tested Miranda’s most complicated components first, and now we’re in the final stages of building the first development engines,” said Brigette Oakes, Ph.D., Director of Propulsion at Firefly. “Our engines are designed to allow for the natural evolution to considerably higher thrust.”

With 230,000 pounds of thrust (lbf), Miranda is building on the success of Lightning (15,759 lbf) and Reaver (45,000 lbf) with proven engine scalability. Miranda uses the same engine architecture, injector design, and patented tap-off cycle as the Reaver and Lightning engines that power Firefly’s orbital Alpha vehicle. Miranda also incorporates a scaled-up version of Reaver’s turbopump, fluid systems, and valve technology. The company used extensive data from more than 500 Reaver and Lightning engine tests, accounting for more than two hours of run-time, to scale the Miranda engines and improve reliability.

Following Miranda’s first hot fire test this summer, Firefly will start engine qualification this fall. The company’s culture of rapid design, iteration, and agility further enables Firefly to meet MLV’s schedule with a cost-effective, high-performing solution.

About Firefly Aerospace

Firefly Aerospace is an end-to-end space transportation company developing a family of launch vehicles, in-space vehicles, and services to provide industry-leading affordability, convenience, and reliability to government and commercial customers. Firefly’s small- to medium-lift launch vehicles, combined with its spacecraft, such as the Space Utility Vehicle (SUV) and Blue Ghost lunar lander, provide the space industry with a single source for missions from LEO to the surface of the Moon and beyond. For more information, visit


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Firefly’s first Miranda engine chamber hardware for development testing; January 2023
Miranda’s throttle valve being tested on a Reaver engine; February 2023
Miranda’s throttle valve being tested on a Reaver engine; February 2023
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