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Stoke Space Hotfire Tests New Booster Engine For First Time

Stoke Space has successfully completed the first hotfire test of their new full-flow, staged-combustion (FFSC) rocket engine; which is set to power the first stage of Nova, Stoke's fully reusable medium-lift launch vehicle.

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Zac Aubert

Zac Aubert

Tue Jun 11 2024Written by Zac Aubert

Stoke Space has successfully completed the first hotfire test of their new full-flow, staged-combustion (FFSC) rocket engine; which is set to power the first stage of Nova, Stoke's fully reusable medium-lift launch vehicle.

The test was conducted on June 5 at Stoke's testing site in Moses Lake, Washington.

During the test the engine; designed to produce up to 100,000 pounds of thrust, reached 50% of its rated thrust during the two-second test. Going from rest to producing the equivalent of 350,000 horsepower in just under one second. The engine then held the power level before shutting down.

The test aimed to assess the engine's startup and shutdown processes.

"All of the complexity and a lot of the risk is in that startup transient and shutdown transient...The duration of the test was short because the goal was to demonstrate the transient and then back out." - Andy Lapsa, CEO of Stoke Space

The engine utilizes a full-flow staged combustion design, where both the fuel (liquified natural gas) and the oxidizer (liquid oxygen) pass through separate preburners before entering the main combustion chamber. Stoke plans to use seven of these engines on the first stage of Nova.

The FFSC engine is widely regarded as the pinnacle of rocket propulsion technology due to its unmatched efficiency and performance. This approach offers greater efficiency and a longer engine life but is more complex to develop. Currently, only SpaceX's Raptor engines, which power the Starship vehicle, use this technology.

"In a world of rapid reuse, you need high performance...Full-flow staged combustion gives you the highest performance possible under the least stressing conditions." - Andy Lapsa, CEO of Stoke Space

This advanced engine technology is set to enable Stoke's reusable vehicle to undertake missions to various orbital destinations while maintaining the conservative margins necessary for a long service life.

"We are incredibly proud of this achievement...Our team has worked tirelessly to bring this engine to life in record time. This successful test is a testament to their talent and dedication, and it puts us one big step closer to bringing the Nova launch vehicle to market. Nova has unique capabilities that give commercial, civil, and defense customers access to, through, and from space." - Andy Lapsa, CEO of Stoke Space

Remarkably, Stoke's engineering team designed and manufactured this first-stage engine in just 18 months.

Stoke's conducted a successful vertical takeoff and vertical landing (VTVL) developmental test flight of its reusable second stage in September 2023.

The upper stage employs a different engine technology, with liquid oxygen and liquid hydrogen fueling an engine integrated into an actively cooled heat shield to allow the upper stage to return for a powered landing.

Throughout 2024, Stoke aims to refine its engine and vehicle design while scaling operations for orbital launch.

While there are some commonalities between the booster and upper stage engines in terms of technology used in the engines' turbomachinery and analysis tools, Stoke has confirmed that the first stage booster is very much an entirely new and different system.

Stoke is progressing on other vehicle aspects as well. The engine tests used flight avionics and software, and the company is undergoing a "design iteration" on the upper stage. This work is funded by a $100 million Series B round raised last October.

Stoke set an internal goal of starting orbital flight tests in 2025, with a desire to expedite this timeline, no target launch windows or updates have been given yet as it depends on when the company can begin work on the vehicle's launch site at Cape Canaveral’s Launch Complex 14; which was allocated by the Space Force last year.

"I think that you’ll find over time, just like fully rapidly reusable rockets will render all others obsolete, I think that these high-performing engines that make that mission possible will render over time the lower-performing variants also obsolete. I think it’s an essential technology mountain to climb, and I’m really excited to be on that mountain." - Andy Lapsa, CEO of Stoke Space

About Stoke Space

Stoke Space is revolutionizing the space economy by providing low-cost, on-demand transport to, through, and from space.

It is developing fully and rapidly reusable rockets and space vehicles designed to operate with aircraft-like frequency.

Stoke’s technology development is funded by the U.S. Space Force, NASA, the National Science Foundation, and other government and private partners.