Houston SpaceportOn a cloudy day in late March, Andrew Doggleby guided me to a safe distance away from the rocket engine. We didn’t have to go very far, maybe 50 metres, because the prototype engine designed and built by his small engineering team isn’t that big.
We waited a few minutes before steam started coming out of the engine. And then, for a few seconds, the engine made a characteristic whistling sound. “that is it!” exclaimed Duggleby. by He. SheHe meant the sound of a rotating detonation engine firing after it was ignited. The sound indicates that the reaction has been successfully rotating at 20,000 times per second around the engine.
Duggleby is the chief technology officer of a company he co-founded with his wife, Sassy. Venus Aerospace aims to build a hypersonic aircraft that can carry perhaps a dozen passengers and travel at the astounding 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?” Sassi Doglebi asked me.
Going truly fast
Too many, probably. And I came to Venus Aerospace’s facilities in southeast Houston to see if there was any chance the company would achieve this ambitious goal.
Of course, I had some doubts. One problem is that the Mach 9 is really, really fast. No plane has moved so fast. The fastest aircraft ever built is the Lockheed SR-71 “Blackbird”, which traveled at Mach 3.2. Anything above Mach 9 will lose communications with Earth, as plasma begins to envelop the craft, as if it were a spacecraft returning to Earth through the upper atmosphere.
In terms of passenger travel comparisons, the supersonic Concorde traveled at Mach 2, or about 2,100 km/h. Most of the newer generation supersonic aircraft in development today are in about the same range, such as the Boom Supersonic’s cruising speed of Mach 1.7.
Duggleby’s suggests a radically different flight profile. They intend to take off their planes and then make a 10-minute boost with their rocket engine. This will send the aircraft about 50 km high, or half the distance into space. Oh, and they’re aiming for an airport-like operating cadence of four flights a day.
To that end, the company recently decided to use a fuel blend for its engine: room-temperature hydrogen peroxide and Jet-A, the fuel used by the majority of jetliners already flying at airports. The company’s engineers also recently achieved liquid peroxide detonation and Jet A, which is important for using a stable fuel formulation.
One key to making all of this work is to use a new type of engine based on “rotary 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 missile engines.
In a conventional rocket engine, a high-pressure propellant and an oxidizer are injected into the combustion chamber where they burn and produce a high-energy plume of exhaust—Newton’s second law of motion. The rotary detonation engine differs in that the detonation wave travels around a circular channel. This is maintained by the injection of fuel and oxidizer and produces a shock wave that travels outward at supersonic speed.
This all sounds rather complicated, and it is. But a growing number of groups in Japan, Europe, the United States, and elsewhere have produced and tested such engines, so it’s more than just a theory. In lab tests, the engines provided a 10 percent increase in fuel efficiency.
It may not sound like much, but it’s a standout number for Venus Aerospace. By mass, hypersonic aircraft make up about 80 percent of the fuel and oxidizer. By increasing this fuel efficiency, there is actually mass left over for important things like landing gear, wings, and even some passengers. “It really allows us to build a vehicle that is more like an airplane,” said Andrew Doggleby.
At the same time that Venus Aerospace is working on its rocket engine, the company has also begun testing drones to improve the shape of its aircraft. Recently, a 5-foot-tall drone demonstrated fully autonomous flight in California. Venus aims to reach supersonic speed with an 8-foot drone before the end of this year and hit Mach 3 by early 2024 with a rotating detonation engine.
The company has about 80 full-time employees and 20 contractors, most of whom work out of the company’s hangar at Spaceport Houston. Venus Aerospace has raised $41 million to date, led by Prime Movers Lab, and Sassi Doglebi said it’s working to raise a second round of funding.
She and her husband previously worked at Virgin Orbit before founding Venus Aerospace in the summer of 2020. They feel it’s important to have a company that works hard, but also works reasonable hours.
“We like to say ‘home at dinner,’” she said. “This is for both our employees and our customers who travel the world.”
Venus Aerospace still has a very long way to go. But it appears she is taking the right steps at the beginning of her journey.
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