Horizon Aircraft just made aviation history, becoming the first eVTOL to achieve a stable wing-borne flight transition using a fan-in-wing design with its "large-scale" Cavorite X7 demonstrator. The best part is that this particular aircraft is meant to be just that, a conventional aircraft – that just happens to be able to take off and land vertically like a helicopter.
It works by having 14 fans embedded within the wings. Five per main wing with a pair in each forward canard. Horizon designed a clever patented mechanism that allows the wing surfaces to slide open for vertical lift from the battery-powered fans, and slide closed as the X7 transitions to forward winged-flight, like a normal plane, with a gas-powered turbine engine powering the rear push-prop.
Using this system, the turbine would also charge the power-hungry fan system mid-flight, giving you a full battery when you arrive at your destination. And this is one of the important bits: Being able to charge while in flight means quick turnarounds. Be it rescue missions or ferrying people across town and back. Topped-up batteries at your destination will give you the choice to land conventionally or simply toss the X7 into hover mode and land anywhere you can fit a 50-ft (15-m) wingspan and 38-foot (11.6-m) fuselage.
That means almost any H1-H3 rated helipad, aircraft carrier, hospital roof, ski resort, you name it – as long as the final approach and takeoff area (FATO) is 1.5 times the overall length of the X7 and the touchdown and lift-off area (TLOF) weight isn't exceeded.
The Cavorite – named after the fictional anti-gravity substance from H.G. Wells' 1901 book The First Men in the Moon – is designed to carry six passengers plus a pilot. With a maximum gross weight of 5,500 lbs (2,500 kg), it can haul up to 1,500 lb (680 kg) of cargo for vertical takeoffs, or 1,800 lbs (815 kg) for conventional runway launches.
Because it can operate as a conventional plane, the X7 will be rated for both instrument flight rules (IFR) and visual flight rules (VFR) operations, capable of handling all weather conditions – including known icing conditions. If certified, it will become the very first in its class to have such a rating.
Also, unlike most air taxis we've seen, the Cavorite X7 is built for serious speed and range. Horizon says it'll be good for a 288-mph (463-km/h) cruising speed with an impressive 500-mile (800-km) range with reserves. That's around five times further than competitor Archer Aviation's all-electric Midnight eVTOL.
There is some competition, however, as last year, Joby put a hydrogen-electric variant of its flagship, five-seat, tiltrotor "hexaprop" S4 air taxi to the test, completing an unprecedented 523-mile (841-km) non-stop flight ... with only water for emissions. But that was a one-off (perhaps more to come though?). The standard all-electric S4 has a cruise speed of 200 mph (322 km/h) and a range of up to 150 miles (241 km) before it needs recharging.
So why fans in wings?
"We wanted to take a normal airplane and not mess with it too much. It needs to return to normal wing-borne lift as soon as possible," Brandon Robinson, CEO (and co-founder with his dad, Brian) of Horizon Aircraft and former USAF F-18 fighter pilot told New Atlas. "When you watch a helicopter take off, they don't rise up vertically for 500 feet. They transition to forward movement very quickly."
Using wings for lift during forward movement is far more efficient than using fans or rotors. Especially when paired with a turbine engine providing propulsion. The forward-swept wing design isn't just because it looks cool either. The design improves handling at low speed and higher angles of attack (AoA), which is critical for transitioning smoothly from hover to winged flight. Typically, anything between 15° to 20° is considered a high AoA – lots of lift, but lots of drag. And the slower you go, the more unstable such an AoA becomes, so forward-swept wings were the obvious choice.
Because of its high AoA design, the X7 also has STOL capability. A runway of only 1,000 ft (305 m) should be plenty for the X7 to do short takeoffs and landings. That puts it on the extreme minimum end as the most popular 4-seater, single-engine private plane in the world – the Cessna 172 – which can generally get airborne in about 1,000 feet with a really light load in perfect conditions.
The 14-fan system is highly redundant and compartmentalized. The unmanned demonstrator was able to hover with 30% of its fans turned off. Each fan is electrically, thermally, and mechanically isolated, meaning one fan failing won't cripple the entire aircraft. And electric fans are much quieter for urban operations where this type of aircraft is likely to spend a majority of it's low-altitude time.
Horizon has stated on its website that as battery technology evolves and becomes better, the Cavorite can become fully electric.
It's been years in the making, with New Atlas having covered Horizon's unique eVTOL design as early as 2021 and when the company was still talking about building a 1:6 scale Cavorite X5 demonstrator. Only a few short years ago, the Toronto-based company considered using a Chevy LS3 V8 engine on pump gas as its powerplant coupled with a battery system.
"From a certification perspective, what I like about our design specifically is that we can talk to the FAA regulators and say 'Look, this is a normal airplane. It never has to be a VTOL. The VTOL portion of this airplane is just a layer of safety on top. It's automated. If you go too slow, instead of the airplane stalling, the wings open and it hangs out. It's good to go.'" said Robinson in an earlier interview with New Atlas.
The design hasn't really changed much since 2021. Frankly, it doesn't look like it needs to. It looks like a hammerhead shark with wings, and that's just cool.
Source: Horizon Aircraft
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