HOUSTON SPACEPORT—On a cloudy day in late March, Andrew Duggleby guided me to a safe distance from a rocket engine. We didn’t have to go far, maybe about 50 meters, because the prototype machine designed and built by his small engineering team was not that big.
We waited a few minutes before steam started to hiss from the engine. And then, for a few seconds, the machine made a strange whistling sound. “There!” exclaimed Duggleby. Through this, he meant the sound of the rotating detonation engine firing after its ignition. The sound indicates that a reaction is successfully rotating 20,000 times a second around the engine.
Duggleby is chief technology officer of a company he founded with his wife, Sassie. Venus Aerospace aims to build a hypersonic aircraft that can carry perhaps a dozen passengers and travel at the super-fast speed of Mach 9, or more than 11,000 kilometers per hour.
“How much would the world change if you could get anywhere in an hour?” Sassie Duggleby asked me.
will go Really fast
Quite a few, probably. And I went to Venus Aerospace’s facilities in southeast Houston to see if there was any chance the company would reach this ambitious goal.
Certainly, I had some doubts. One problem is that Mach 9 is actually very fast. No plane has ever landed this fast. The fastest plane ever built was Lockheed’s SR-71 “Blackbird,” which traveled at Mach 3.2. Anything above Mach 9 and you lose communication with the ground, as the plasma begins to envelop the vehicle, as if it were a spacecraft returning to Earth through the upper atmosphere.
In terms of passenger travel comparisons, the Concorde supersonic airliner traveled at Mach 2, or about 2,100 km/hour. Most of the newer generation of supersonic aircraft being built today are in roughly the same range, such as the Boom Supersonic’s cruising speed of Mach 1.7
Duggleby’s suggests a unique flight profile. They intend to fly their aircraft and then perform a 10-minute boost with its rocket engine. This will send the aircraft to an altitude of about 50 km, or half way to space. Oh, and they aim for an airport-like rhythm of operating four flights a day.
To that end, the company recently decided on a fuel mix for its engine: room-temperature hydrogen peroxide and Jet-A, the fuel used by the majority of jet aircraft already flying at airports. The company’s engineers also recently achieved liquid peroxide and Jet A detonation, which is important for the use of a stable fuel composition.
A great machine
A key to making all this work is the use of a new type of engine based on “rotating detonation.” Governments around the world have been researching this technology for more than a decade because it has the potential to increase fuel efficiency in a variety of applications, from US Navy ships to rocket engines.
In a traditional rocket engine, a high-pressure propellant and an oxidizer are injected into a combustion chamber where they burn and produce a powerful plume of exhaust—Newton’s second law of motion in action. A rotating detonation engine is different in that a detonation wave travels around a circular channel. It is sustained by fuel injection and oxidizer and produces a shockwave that travels outward at supersonic speeds.
It’s all a bit complicated and, well, it is. But a growing number of groups in Japan, Europe, the United States, and elsewhere have built and tested such machines, so they are more than theoretical. In lab tests, the engines provided about a 10 percent increase in fuel efficiency.
That may not sound like a whole lot, but it’s a make-or-break number for Venus Aerospace. By mass, hypersonic aircraft are about 80 percent fuel and oxidizer. By increasing fuel efficiency, there is actually mass left over for essentials like landing gear, wings, and even some passengers. “This allows us to truly build a vehicle that looks like an airplane,” said Andrew Duggleby.
Send in the drones
Along with Venus Aerospace working on its rocket engine, the company has also started testing drones to refine the shape of its plane. Recently, a 5-foot-long drone demonstrated fully autonomous flight in California. Venus aims to go supersonic with an 8-foot drone before the end of this year and reach Mach 3 in early 2024 with a rotating detonation engine.
The company has about 80 full-time employees and 20 contractors, most of whom work at the company’s hangar at the Houston Spaceport. Venus Aerospace has so far raised $41 million, led by Prime Movers Lab, and Sassie Duggleby says she is working on raising a second round of funding.
He and his wife both previously worked at Virgin Orbit before founding Venus Aerospace in the summer of 2020. They felt it was important to have a company that both worked hard, but also worked reasonable hours.
“We like to say ‘Home for dinner,'” he said. “That’s both for our employees and our customers who travel around the world.”
Venus Aerospace has a very long journey. But it seems to be taking the right steps at the beginning of its journey.