A Houston Hypersonic Transport Startup Promises Passenger Flights From L.A. To Tokyo In An Hour

If you’ve been around long enough, you may remember eyeglass retailer LensCrafters catchy advertising slogan, “Glasses in about hour!” Houston-based startup, Venus Aerospace promises it’ll transport you from Los Angeles to Tokyo in the same span using a spaceplane starting in 2030. It’s a promise that’s hard to see.

The company hasn’t released images of the design of its 12-passenger airliner. On the other hand, it has just issued a release touting the $20 million Series A funding it has raised in conjunction with Prime Movers Lab, a Wyoming venture capital firm that describes itself as investing in “breakthrough scientific startups.”

Venus Aerospace has now raised a total of $33 million. In its year-plus in existence, the startup has grown to 40 employees and operates from a hangar at the Houston Spaceport (Ellington Airport). The release boldly states that “Venus Aerospace is building a zero-carbon emission spaceplane that will enable one-hour global travel.”

However, Venus’ hypersonic transport will not be carbon emissions-free. Nor will it be a spaceplane. Venus joins an emerging slate of hypersonic transport hopefuls, including Atlanta-based Hermeus and the just-announced Beijing-based Space Transportation, which says it will fly passengers from Shanghi to New York in just two hours.

All three claim they’ll be flying full-scale airplanes at Mach 5-plus (where hypersonic speed begins) by 2030. All three embrace the idea of bringing the world together through high-speed transport, as does the comparatively pokey supersonic aspirant Boom.

Venus has tossed around the catch phrase “Home By Dinner” to describe a theoretical L.A. to Tokyo round trip in a business day by a smart executive bent on supping with the family. Hermeus swaggeringly issues the challenge “Race You There.”

The vision and the hype bear some resemblance to the low-altitude but metaphorically high-flying Urban Air Mobility scene and its as yet unrealized (but always just around the corner) market.

What destination Venus Aerospace and its would-be competitors are realistically heading to is a worthwhile question.

A Hypersonic Hybrid

One might compare Venus’ proposed aircraft to a hybrid car. Like the parallel combustion engine and electric drivetrains common in such vehicles, the company’s hypersonic design will rely on two propulsion systems — a conventional jet engine and a rocket.

It’s a strategy that differs markedly from Hermeus’ air-breathing Turbine-Based Combined Cycle Propulsion (TBCC) engine approach or what looks to be Space Transportation’s solid rocket booster-liquid-fueled main rocket combination.

Venus’ theoretical operational concept is what drives the choice, according to company co-founders and spouses Sarah and Andrew Duggleby. Both are aerospace veterans with stints at Virgin Orbit and Virgin Galactic. Both have engineering backgrounds (Andrew is a former mechanical engineering professor at Virginia Tech and Texas A&M and a Navy reserve engineering duty officer), with Sarah (or Sassie as she’s known) serving as CEO and Andrew as CTO.

The aircraft that Venus says it will build is intended to largely plug into the existing air transportation infrastructure. They say it will be able to take off from a standard runway at LAX and climb to a nominal conventional cruise altitude (35,000 feet or thereabouts) using its jet engine. Then the jet is shut down and its inlet/exhaust is closed off. As that happens, a liquid-fueled rocket engine fires.

The rocket accelerates the aircraft to Mach 9 (about 6,850 mph) at approximately 0.5 g of acceleration (slightly more than an airplane on takeoff, according to Andrew) as it climbs to a peak altitude of 170,000 feet. It takes roughly 10 minutes for the airplane to reach Mach 9, a speed it holds for a further five minutes.

The rocket then goes out and the airliner becomes a hypersonic glider, descending unpowered toward its destination for 45 minutes, decelerating at around 0.1 g. Once back to near 35,000 feet, the jet engine is restarted and the aircraft joins common airliners in the air traffic control queue for vectors to landing at Narita (Tokyo).

It sounds potentially doable at some point in the future, but a lack of specificity about the details and business plan is glaring.

Impossible To Hard

Andrew Duggleby says that in Venus Aerospace’ short history, “We’ve gone from the impossible to the hard but there are still a lot of hard things left.”

The Venus team say they’ve made three key advances that have moved the project out of the realm of the impossible. The first is a patented rotating detonation rocket engine (RDRE). The second is the aircraft shape. The third is an active cooling system.

In simple terms, an RDRE detonates rather than combusts its liquid propellant. A ring-shaped (annular) reactor within triggers chemical reactions that push concentric pulses of supersonic gas out the exhaust nozzle, generating thrust.

RDREs are noted for producing more thrust with less fuel than conventional rockets, burning the fuel more completely at higher temperatures. They potentially offer heat transfer and other advantages including weight and compactness. Andrew says the engine Venus has developed and lab tested at small scale is 15% more fuel efficient than comparable rockets, freeing aircraft mass for passengers and practical things like a pressurized cabin and landing gear.

The funding Venus has raised so far has allowed it to get to a point where, “We have proved that we have a way to achieve our detonation engine, that there are ways to keep it cooler,” Duggleby maintains.

He has loosely compared the fuel his engine will use to the mixture used by the Space Shuttle, whose main engine burned liquid hydrogen and liquid oxygen. But unlike hypersonic cargo aircraft developer Dawn Aerospace, which has revealed its rocket engine will use a liquid mixture of high-test peroxide (HTP) and kerosene, Venus isn’t sharing the composition of its liquid fuel, stating that it is a “key part of how we keep the engine cool.”

The company is also staying silent on the design of its airframe, which will have to fly and maneuver well at both slow subsonic and hypersonic speeds. Duggleby allows that it is a “waverider,” shaped to create a single shockwave and to trap a pocket of high-pressure air under the belly of the vehicle for increased lift.

NASA’s Boeing X-51 is a useful waverider example but whatever Venus comes out with (it has yet to narrow from five candidate shapes) will likely look different. For a start it will have passenger windows and a conventional tail. Whether it has front cockpit windows for pilots has not yet been determined.

Andrew Duggleby says Venus will “hopefully be unveiling” the airframe soon but won’t discuss a timeline. Subscale model tests have been done at the University of Arizona’s Mach 5 wind tunnel, where Venus has even done some validation “at that speed.”

As with other hypersonic concepts, moving at Mach 9 can be expected to generate a lot of heat. Duggleby says doing so at 170,000 feet is an advantage because the thin atmosphere there offers less heat friction than at lower altitudes. Heat will affect the aircraft’s nose in particular, a problem Venus says it will surmount with a 3D-printed nose with a novel internal cooling scheme. Duggleby describes it as a “heat pipe on the leading edge which actually spreads the heat out.” The leading edges of the wings may include a similar system.

The rest of the airplane, he says, will not use exotic materials to dissipate heat. It will utilize “standard aerospace material” to keep costs down, though Duggleby won’t specify what.

Despite a decided lack of public information on its three technology keys, Venus Aerospace enjoys the confidence of its venture capital backers. Sassie Duggleby characterizes the group of investors assembled by Prime Movers Lab as “patient capital.”

Prime Movers Lab technical partner Liz Stein says the startup has a “hardware rich program,” citing the successful hot-fire of its proof-of-concept engine, subscale model wind tunnel testing and collaboration with Georgia Tech for the leading edge cooling design.

Stein added that Prime Movers has supported Venus with introductions to hypersonics personnel at NASA, and shared analysis tools and research papers. She also pointed to NASA-Deloitte and NASA-SAIC market studies describing the demand for hypersonic air transport, which Stein asserts suggest that “the market demand signal is there for high-speed flight systems to operate profitably without government assistance.”

Not everyone agrees and many point to the example of the Concorde, which required the support of multiple governments and never broke even.

“Haters always point to the Concorde to dismiss the commercial viability of high speed flight, without understanding why Concorde failed,” Stein says.

She maintains that it had to do with the massive upfront capital required ($18.8 billion) and the operational recurring costs. Chief among the latter was fuel gobbled by the Concorde’s Olympus 593 engine whose afterburners used so much juice on takeoff that “more than half the take-off weight of the Concorde was fuel.”

That, in turn, required untenable per-seat ticket prices for the approximately 100-passenger supersonic airliner. The implication is that Venus’ hypersonic transport will not have such a problem. However, since we don’t know what rocket fuel mixture it will use and liquid propellant costs widely vary, estimating cost is difficult to impossible.

Venus’ proposed aircraft will carry fewer passengers and likely be smaller than Concorde. With its hybrid propulsion it may consume less net energy but its fuel cost (and overall operating cost) will be spread across just 12 seats on every flight. Calculating a fuel bill for an aircraft not even experimentally realized seems a risky exercise for the most patient investor. That may not matter, however.

Several reports on Venus Aerospace suggest it is on track to achieve revenue generation in the next two years. It would presumably do so by sharing its intellectual property with the Defense Department. As AFWERX’ $60 million investment in Hermeus shows, the Air Force and DoD in general are in a lather about advancing hypersonic technology for missiles, reusable drones, satellites and aircraft, as well as spurring private sector growth.

DoD’s enthusiasm is not for hypersonic commercial transports. Rather it’s seeking realistically achievable smaller vehicles on short timelines. A senior official in the defense/government science and technology establishment told me, “If DoD is concerned about hypersonic, they might be concentrated on defeat [i.e. countering hypersonic weapons]. They might need to test defeat [systems] and a drone might enable that.”

Like Hermeus, Venus Aerospace is planning to develop a drone first to prove out its technology. Whether either company eventually gets to a hypersonic transport arguably isn’t central to their respective business cases or to their investors.

Spaceplane or Bust

It’s been estimated that Boom, which is further along its path than Venus, will need well over a billion dollars to realize its supersonic transport.

When asked about total costs for Venus, after a long pause, Sassie Duggleby says their estimate is in the “billion-dollar range.” She couples this with the caveat that Venus has “opportunities for early stage revenue with the drone. It’s not spaceplane-or-bust.”

“Using government funding to help buy down this risk is one of our key things, she says. “We don’t believe we need a full billion dollars in venture capital funding before we get there.”

Venus says it already has some government funding to help it get there. That may come from an AFWERX Small Business Technology Transfer (STTR, Phase I-II) contract, though I was unable to confirm this. If so, it has probably yielded Venus around $800,000.

The startup path is one the couple say they’ve eagerly embraced after years with established companies. In that vein, Sassie says, “Are we going to learn things and think we need to pivot? Sure, but that’s the joy of the startup world. That’s the joy of innovation.”

It seems like mixed messaging, a feature also lodged in Venus Aerospace’ claims to build a carbon-free spaceplane and be flying by 2030. Those paying close attention will realize that space is generally agreed to start at 62 miles (330,000) above the Earth. Sassie Duggleby acknowledges that Venus’ notional vehicle only gets about halfway to space — or to the Mach it would need to escape earth’s gravity. Why call it a spaceplane then?

“We call it a spaceplane because it gets mostly there,” Andrew Duggleby offers. “We are not an air-breathing vehicle. We’re not just a fast jet. So it’s better to call it a spaceplane.”

When I point out that fare-paying passengers might expect to go to space on a spaceplane, Sassie replies that, “When you say spaceplane, people tend to understand that it’s not just a standard jet.”

They might also understand that Venus’ jet and rocket are unlikely to be carbon emissions-free (not to mention the inputs to building such a transport). Lower carbon biofuels and synthetic aviation fuels are on the horizon but whether they’ll be widely available (or price competitive) by 2030 is a question.

As for the rocket, the Space Shuttle emitted mostly water vapor from the liquid fuel it burned. Venus’ aircraft isn’t expected to run on the same stuff. And scientists say we don’t have very good data on what liquid fueled rockets emit, particularly in the upper atmosphere. Whatever rocket fuel a hypersonic Venus Aerospace airliner burns, it will also need special handling at airports or spaceports.

Andrew Duggleby says this isn’t a major challenge though fuels and security experts may disagree. One may remember that Airbus’ huge A380 has been shut out of a number of airports for considerations as mundane as a need for reinforced ramp/runway material and different air bridges for passenger emplaning/de-planing.

One would also have to guess that Venus’ hypersonic airliner would need 10,000-foot runways (Andrew says they have 15 candidate routes/destinations) and possibly have a high final approach speed with air traffic implications. The Dugglebys don’t see any major bumps in the road there.

Surprisingly, they say that Venus will be vertically integrated, including building its own rocket engines. The usual suspects from United Launch Alliance to Northrop-Grumman to SpaceX aren’t part of their plan, which will apparently see engines manufactured at the company’s Houston Spaceport facilities.

Some portion of Venus’ 40-member staff has rocket building experience its chief officers say. Whether that experience is more drone/subscale vehicle focused than full-scale vehicle I didn’t ask. What volumes will be needed is another question that went unanswered. It gets to the heart of the business proposition.

Venus has made no public projections on the cost of its aircraft. What tickets might cost is similarly unknown. Sassie says the company has internal cost models. “We would like to keep it close to a first-class ticket price. There are lots of factors and we’re still in the early stages of what that will actually look like.”

Those factors include flight frequency. Venus’ cooling methodology and airframe design will make a two-hour aircraft turnaround possible, Andrew Duggelby maintains. Venus is targeting four flights a day. Unlike the Space Shuttle’s main rockets which had to be torn down after every flight, the RDREs in Venus’ airplanes will perform 100 scheduled flights before necessary engine checks and 1,000 flights before a rebuild level check. “Yes, this is a tall order,” Andrew acknowledges, “but our initial design shows feasibility.

Feasibility has been a question as long as serious hypersonic flight efforts have been around from British Aerospace’ early 1980s HOTOL reusable conventional takeoff/landing vehicle to NASA’s Reagan-inspired late 1980s Orient Express hypersonic plane project.

Venus Aerospace’ CEO referred to the venture several times as an “early stage technology company,” which it undoubtedly is. Its parts may in fact be worth more than the whole. That’s why it curious that Venus or other would-be hypersonic transport builders would publicly trumpet a 2030 “gonna-fly” goal.

The reason, says AeroDynamic Advisory’s Richard Aboulafia, comes down to investment dollars. “HOTOL, Orient Express and others were five to 10 years away’ in the 1980s. Today hypersonic [transports] are five to 10 years away. What a surprise.”

“Urban Air Mobility has attracted billions of dollars. Yes, a lot of it is ridiculously over-hyped but the objective [of UAM companies] is to accrue money. That’s job one.”

Could Venus Aerospace attract the billion dollars it says it needs to build a hypersonic transport? “Look at the investment that UAM attracted last year,” Aboulafia says. “The joke’s on us. As for a billion, spoiler alert — it’s not enough.”

The Dugglebys extend the “Home By Dinner” metaphor to Venus Aerospace’ focus on work-life balance, a feature missing from most aerospace companies they say. How that matches up with designing, testing and building a full-scale flying hypersonic airliner by 2030 isn’t clear. Assiduously avoiding the things that delay a project timeline – misdirected work, re-work, over complication – will help, they assert.

Pressed further, Andrew says the 2030 objective is really a “no earlier-than” timeline. Sassie says it’s something to strive for, that maybe it takes an extra five years to “get to a product as fast as possible.”

“We’re not compromising on our mission statement as a company,” she affirms. Hypersonic transport is “absolutely the reason we decided to start the company two years ago. The market opportunity is incredible.”

When LensCrafters got going in the early 1980s, it linked its tagline to a commercially and technologically achievable goal. As things stand in 2022, it seems it would take some special glasses to see if Venus Aerospace has done the same.


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