Engine developer and manufacturer Ursa Major has hot-fired its new Draper liquid engine dozens of times since the first test in early March, a strong early endorsement of the performance and reliability of the 4,000-pound thrust powerplant that the company touts as well suited for hypersonic defense and target applications, and for in-space propulsion.
The 50-plus hot-firings of the first test article at Ursa Major’s headquarters north of Denver in Berthoud, Colo., have occurred under a year-old contract with the Air Force Research Laboratory (AFRL), which also enabled the building of a test stand specific to Draper, the startup company said on Thursday. The AFRL award was signed March 10, 2023 and lasts 27 months.
Joe Laurienti, Ursa Major’s founder and CEO, said on Wednesday that he has worked on seven or eight liquid engine programs in his career and “definitely I’ve never seen a first article engine last 50 fires.” Given the performance and reliability shown so far, he likened the initial testing to the development of aircraft engines rather than a hypersonic rocket engine.
“And it’s probably very fitting for its hypersonic use cases that it’s intended to be just ultra-reliable and ultra-operable,” he told reporters during a virtual media roundtable ahead of the announcement.
The AFRL contract is aimed at designing, building, and then verifying the operability of Draper’s architecture and testing has already gone well beyond that, he said.
Laurienti was a propulsion engineer with rocket companies SpaceX and then Blue Origin before founding Ursa Major in 2015.
“Perhaps the most impressive aspect of this program is the delivery of a versatile, storable rocket engine in such an incredibly short timeframe,” Shawn Phillips, chief of AFRL’s Rocket Propulsion Division, said in a statement.
Laurienti in March mentioned the first hot fire of Draper following the successful first flight test of another of the company’s liquid engines, the 5,000-pound thrust Hadley, which boosted the first powered flight of Stratolaunch’s Talon-A test vehicle to high supersonic speeds (Defense Daily, March 11). Stratolaunch is developing Talon as a privately funded hypersonic test capability.
Ursa Major describes the non-cryogenic liquid propellants of Draper as having the storability of a solid rocket motor, which means it is safe for future hypersonic applications where it must be ready to fire at a moment’s notice. The engine is fueled by hydrogen peroxide and kerosene—the kerosene can be shut off so that it runs on a single propellant—and can be throttled down below 10 percent of maximum power, a feature that Laurienti said “is really nice for applications like terminal phase or landing on a non-terrestrial surface.”
AFRL first approached Ursa Major several years ago saying it wanted an engine like Hadley but with storable propellants, so Draper grew out of “thought experiments” around this need for a hypersonic engine that meets these operability, safety, reliability, and performance needs, Laurienti said.
The initial hot fire tests were two to three seconds and, so far, none have been fired for a minute, Laurienti said. Testing has been done in mono- and bi-propellant modes, he said. Laurienti described the current testing as the “fun phase” in terms of pushing Draper’s limits, understanding the environments it can operate in, the “keep out zones,” and “where does the engine not like to run?”
About 10 engines will be manufactured for testing into 2025 to continue assessing Draper’s characteristics and limits, Laurienti said, highlighting that the “hardware variability of engine-to-engine changes are dramatic.” The company is aiming to have Draper qualified in 2025, and Ursa Major is in talks with partners for flight-testing to begin in 2026, he said.
Draper is designed to be built on the same production line as Hadley, for which the company has demonstrated production of one engine a week and the expectations are the same with Draper, Laurienti said. One U.S. Combatant Command has asked what it would take to increase production of the engine by 10 times, he said.
The current planning horizon is to get to building one Draper a week, Laurienti said, adding that “we’re still a couple of years away from going beyond 50 engines in a year.”
Ursa Major is “most interested” in aerial target applications for Draper, including in uses to simulate hypersonic weapons, boost glide systems, and cruise missiles, Laurienti said. Other potential uses include with defensive hypersonic weapons given the engine’s active throttle control and throttle range, in-orbit transfer vehicles for large spacecraft, in-space avoidance, insertion into cislunar environment, as a lander engine, and in rotating detonating rocket engines, he said.