Transcend Air plans to launch production of its high speed VTOL hybrid-electric tilt-wing transport in 2025. On the way there it’s stopping at New England Dragway to refine its aerodynamics and flight control system.
Founded a little over a decade ago, the Boston-based company is seeking to upend the regional helicopter transport market with a high-speed tilt-wing aircraft designed to transport four to five passengers and baggage 300-400 miles at cruise speeds up to 400 mph. While Transcend’s Vy 400 will capitalize on vertical takeoff and landing capability to fly from midtown-to-midtown vertiports, it is not designed to compete in the short haul, all-electric Urban Air Mobility (UAM) market.
On the contrary, the Vy 400 combines the familiar tilt-wing, tilt-rotor configuration increasingly adopted by would-be UAM makers with a parallel hybrid propulsion system consisting of a turboshaft engine which distributes power mechanically to its twin prop-rotors and a battery/motor which in turn electrically powers its articulating tail-fan. General Electric’s
Transcend claims the combination will allow the Vy 400 to fly three times farther and twice as fast as battery-enabled eVTOLs. Its use of a largely known configuration with a certified, field-proven turboshaft engine, fly-by-wire flight control and simplified internal systems (no cables, hydraulics, or fuel lines) will allow it to get through FAA certification and to market faster than UAM aircraft as well.
Transcend Air COO and co-founder Peter Schmidt says the company will finalize its design by year’s end. Though he says Transcend is already “in talks” with FAA regarding certification, it has yet to submit its design to the agency. It hopes to speed the validation it needs to do that by speeding down a drag strip.
If these near-term goals sound eerily familiar to claims in the inexplicably well-funded Wild West of UAM, it is worth considering that Transcend has flown 16 subscale prototype VTOL aircraft in the last 12 years and that it has landed four U.S. Air Force science and technology OTA (Other Transactions Authority) contracts as part of the service’s High-Speed VTOL Challenge (HSVTOL), a collaboration between AFWERX, and U.S. Special Operations Command (SOCOM). Transcend is partnering with Kaman Aerospace to build both the Vy 400 and a larger military HSVTOL variant called the V-500 Catamount.
“Our approach has always been to fly at subscale as an efficient way to collect necessary data,” Schmidt says. Transcend has verified the scalablity of the Vy 400 architecture using virtual tools like computational fluid dynamics, in-house software and third-party analyses while it concurrently flew VTOL prototypes including the 55-pound one-fifth scale prototype pictured with the headline above.
Its next phase of testing prior to building a full-scale 7,000 pound demonstrator centers on developing integrated flight control laws for its fly-by-wire flight control system for the transitional phase of flight (the transition between hover and forward cruise flight). Transcend could refine its control laws, tilt-wing actuation, power gain tuning, and control surface responses in a wind tunnel as big airframers traditionally do. But that would be very expensive and time consuming.
Instead, Transcend is taking a page from aircraft designers stretching back to the Wright Brothers and Burt Rutan (of Scaled Composites, Voyager fame) who used ground bound test rigs (from bicycles to station wagons) to quickly and cheaply verify aerodynamics. In Transcend’s case the rig includes a 2006 Toyota Sequoia SUV with a 15-foot articulating boom mounted to its lower front frame and rear roof structure.
“It’s a small, small fraction [of wind tunnel cost],” Schmidt affirms. “We’re saving vast sums of money and as importantly, we have much more access and flexibility of access.”
With demand for wind tunnel facilities in the U.S. well outstripping supply, Schmidt says simply scheduling the block of time Transcend would need to test a model of the Vy 400 could take up to 18 months.
“If I had to do 650 or 1,000 test points in a wind tunnel with the inevitable things that don’t go exactly as you want, that could be two weeks of wind tunnel time. That could be half a million dollars in some of these wind tunnels.”
Real-world subscale ground tests are a practical alternative though the venues for such testing are usually airport runways. In fact, Schmidt and company have carried out a few airport-based ground tests. They work but getting cooperation from airports and competing with air traffic means they are far less flexible in terms of test availability.
But Schmidt and one of his colleagues at Transcend have done some amateur drag racing. Their experience acquainted them with New England Dragway, a renowned drag strip in Epping, New Hampshire, that hosts annual NHRA events with 300-plus mph Top Fuel dragsters, among others. They realized that the level smoothness of the drag strip, its quarter-mile of sticky pavement and additional over-run out to 4,000 feet would work for their test rig.
Additionally, they could inexpensively rent the track for a day or successive days in the off-season, practically at their leisure, and make pass after pass all day, accruing the data they require in a hurry. “There’s no competing air traffic,” Schmidt enthuses. “We feel very fortunate to be able to run at New England Dragway.”
As they do so, they’ll use the one-fifth scale Vy 400 model they built for subscale flight tests. It sits atop a servo-actuated mount at the end of the boom which can yaw and pitch the model for desired aero loads. The Vy 400 model itself uses onboard lithium batteries to deflect its tilt-wing/rotor nacelles, tail fan and control surfaces. The Sequoia’s own battery and charging system provide power for boom servos, onboard test software and data collection unit, and cameras.
The whole affair was built and fabricated in-house by Transcend taking inspiration both from other ground aero testing rigs and Hollywood film camera vehicles. The system’s in-house design extends to code, says Schmidt, whose background is in software and embedded systems. His cofounder designed it to be fully automated with aural instructions.
“You literally start with an Excel spreadsheet of test points. The software interprets it. It notices when you apply throttle to the truck at the start line and tells you what speed to run for that test point, when you have enough data for that test point, logs it all and does the initial data-reduction for us – all built into the truck.”
The speeds required are target airspeeds. That’s why you’ll notice the spear-like pitot air data measurement system at the very forward tip of the boom below the Vy 400. Since the model is to scale, they translate well below what the full-size air vehicle will see and are expressed in miles per hour (for the Sequoia driver) as well as knots.
For the tests Transcend will undertake, it will need to go as fast as 105 mph. The overall 4,000-foot length of New England Dragway will be useful as the heavy, brick-shaped Toyota, laden with boom rig and model won’t jump off the line like a dragster. At the model’s one-fifth scale 105 mph is “well into our [full scale] level flight cruise-speed but still pretty far from the scale top speed which would be closer to 180 mph.”
A crew of two – a driver and flight test engineer – will pilot the Vy 400 rig down the track, coached by the aurally-enabled onboard test system. As soon as the driver starts accelerating, the software starts talking “It’ll say, ‘Your target is 63 mph,’ ” Schmidt explains. “It will inform you in increments as you go faster. We’re using airspeed obviously from the air data system, not the speedometer of the truck. When you get to the required speed for the test point, it’ll tell you to hold it. Then it will tell you, ‘Test complete.’ You decelerate, turn around and repeat.”
There will no doubt be many repeat runs down the right and left lanes at New England Dragway when the Transcend team goes there, possibly as early as next week or shortly after Thanksgiving. The iterative test process may one day help produce both a speedy regional tilt wing and a high-speed military VTOL aircraft, suitable for island hopping missions in the Indo-Pacific.
“You circle in on your design and get closer and closer to something that you have strong evidence is going to work. Based on that evidence you invest the money to build something big,” Schmidt says.
If Transcend does, they can partly thank an unlikely pair — a 6,000 pound Toyota SUV and a historic drag strip.