Joby Aviation SHy4 (technology demonstrator)

(Photo credit: Joby Aviation)

SHy4 (technology demonstrator)
Joby Aviation
Santa Cruz, California, USA
www.jobyaviation.com

Founded in 2009 by JoeBen Bevirt, CEO, Joby Aviation is a venture-backed startup aerospace company is located in Santa Cruz and San Carlos, California (USA), that is developing and will manufacture piloted all-electric vertical takeoff and landing (eVTOL) passenger aircraft for fast, quiet, and affordable on-demand air taxi services for the advanced air mobility (AAM) industry. Joby plans to start commercial operations as soon as 2025. Bevirt had previously founded the photography accessory company, JOBY (now owned by the British company, Vivendum). 

Joby Aviation purchased the leading hydrogen aviation developer H2FLY, based in Stuttgart, Germany in 2021 (see “eVTOL Leaders Continue Apace,” Vertiflite, July/August 2022). It has been reported that Joby Aviation has 1,422 employees as of January 2023. According to the SMG AAM Reality Index, Joby Aviation has raised over $2.25 billion USD in funding as of June 2024.

Joby SHy4 hydrogen eVTOL technology demonstrator aircraft
On June 21, 2024, the Vertical Flight Society broke the news (see "Hydrogen Begins to Take Off," Vertiflite, July/August 2024) that the US Air Force was funding Joby “for full-scale prototype and testing of novel hydrogen powerplants for airborne applications.” This had never been explicitly acknowledged before in public.

A few weeks later, on July 11, 2024, the company revealed in a press release and a blog post that their Joby S4 2.0 demonstrator had been modified as a liquid hydrogen eVTOL technology demonstrator. The airframe being used for the technology demonstrator is the Joby S4 2.0 pre-production prototype all-battery aircraft with the FAA tail number N542BJ (the second pre-production prototype), which had been retired after its final battery-eVTOL flight on May 2, 2024. A company representative stated the aircraft, before being transformed into a hybrid-electric liquid hydrogen fuel cell eVTOL aircraft, had already flown more than 25,000 miles (40,000 km) on battery power alone. The conversion from battery-electric to hydrogen-electric took place in a matter of weeks. Internally, the aircraft is referred to as the "SHy4" (pronounced "shy-four") — derived from the designations of Joby's "S4" and H2FLY's "HY4" demonstrator — as indicated by the filenames of the photo in the news release and the photo in the blog post.

The Joby SHy4 set a world record with the longest hydrogen-electric VTOL aircraft flight to date, flying 523 miles (842 km), as no other large VTOL aircraft has flown more than 1,000 feet (300 m) on hydrogen fuel cells. The milestone flight took place near the company's test facilities in Marina, California, USA, on June 24, 2024. The company reported the aircraft landed with 10% of its hydrogen fuel remaining. The company changed the color of aircraft tail and outboard propeller nacelles, as well as the forward surfaces of all of the propeller blades, to a light blue, to indicate that it was a now a hydrogen demonstrator, and the words "hydrogen-electric demonstrator aircraft" were added on the aircraft's inner tilt-prop wing nacelle.

At a high level, 90% of the systems on the aircraft stay the same, says Joby founder and CEO JoeBen Bevirt. We add the fuel cell, the liquid hydrogen system, modify the batteries and we get an aircraft with dramatically more range and endurance.

The pre-production all-battery prototype was retrofitted with a 40-kg (88-lb) vacuum jacketed liquid hydrogen fuel tank installed in the fuselage. The hydrogen in the tank is around 22ºK (-423ºF), with the exterior remaining at ambient temperature, Joby stated. A heat exchanger was also installed under the fuselage to cool the fuel cell assembly. The "H2F-175" fuel cell used was developed by H2FLY, while the insulated hydrogen tank and heat exchanger was developed by Joby Aviation. Joby noted that using most of its own proprietary components reduced the complexity and length of the project. The byproducts of a hydrogen fuel cell powertrain is electricity, water and heat, making this power source environmentally clean.

The company noted that a hydrogen fuel system allows much greater range and payload since hydrogen is much lighter than batteries. Liquid hydrogen in storage expands to a gas and feeds the fuel cells, which then power the aircraft and recharge the batteries in cruise flight. The energy needs for the high power requirements during vertical takeoff and landing come directly from the combination of the fuel cells and the batteries. The original S4 batteries were replaced by a lighter load of supplemental batteries.

The SHy4 aircraft's maximum speed is 200 mph (322 km/h). The demonstrator has a range greater than 500 miles (>804 km) with reserve power. The maximum payload weight of the aircraft is 1,000 lb (454 kg). The aircraft has a very sleek modern design with one high main gull wing, six tilt-props, six high-performance electric motors, its liquid hydrogen fuel cell power source, a V-tail, one front fixed landing strut and two rear fixed wheeled landing gear

Hydrogen is one of the best energy carriers in the world because it’s three times lighter than jet fuel and because we can convert the chemical energy that it contains into propulsion twice as efficiently as a small turbine can convert jet fuel into propulsion, Bevirt says.

Although the SHy4 was only a demonstrator, a future Joby hydrogen eVTOL aircraft would be complementary to their S4 all-battery eVTOL aircraft. Therefore, Joby plans to eventually manufacture aircraft for both short-range intra-city and long-range inter-city (regional) trips. For example, in the USA, a hydrogen eVTOL aircraft could fly from San Francisco to San Diego, California, or fly from Boston, Massachusetts, to Baltimore, Maryland, with no carbon emissions. These flights could bypass the large fixed airports that are limited in capacity by available real-estate and fly directly between vertiports within the cities. Joby noted that if you wanted to design an all-battery aircraft for long range trips, the weight of all the batteries would make the aircraft too heavy to take off. Hydrogen fuel cell aircraft excel for longer flight destinations because liquid hydrogen is 100 times lighter than batteries and three-times lighter than jet fuel.

Joby CEO Bevirt wrote in a blog post that "broadly commercializing hydrogen" requires significant work on "regulation and infrastructure, along with fuel storage and distribution, but we have demonstrated that regional hydrogen-electric flight is possible today." The SHy4 demonstration is hoped to inspire industry and governments to invest the necessary time, effort and capital to expedite the transition of aviation away from fossil fuels.

Specifications:

• Aircraft type: Hydrogen eVTOL technology demonstrator aircraft
• Piloting: 1 pilot
• Maximum speed: 200 mph (322 km/h)
• Range: >500 miles (>804 km) plus reserve power
• Maximum payload weight: 1,000 lb (454 kg)
• Propellers: 6 tilt-props, 4 tilt-propellers tilt vertically including the entire motor nacelle, 2 propellers tilt vertically with a linkage mechanism
• Motors: 6 high performance electric motors
• Power source: Has a hybrid-electric power source using batteries, liquid hydrogen, fuel cells and has a heat exchanger to cool the fuel cell assembly
• Fuselage: Carbon fiber composite
• Windows: Large windows allowing forward, left and right visibility
• Wings: 1 main high gull wing
• Tail: 1 V tail
• Landing gear: 1 front fixed landing strut and 2 rear fixed wheeled landing gear
• Safety features: Distributed Electric Propulsion (DEP) means having multiple propellers (or electric ducted fans) and multiple electric motors on an aircraft so if one or more propellers (or electric ducted fans) or some electric motors fail, the other working propellers (or electric ducted fans) and electric motors can safely land the aircraft. DEP provides safety through redundancy for passengers or cargo. There are also redundancies of critical components in the sub-systems of the aircraft providing safety through redundancy. Having multiple redundant systems on any aircraft decreases having any single point of failure.

Related Aircraft:

• Joby Aviation Monarch (defunct)
• Joby Aviation Lotus (defunct)
• Joby Aviation S2 (defunct)
• Joby Aviation S4 1.0 (technology demonstrator)
• Joby Aviation S4 2.0 (pre-production prototype)
• Joby Aviation S4 (production prototype)

Company Insights:

• Crunchbase
• Future Flight
• MarketWatch
• Pitchbook
• Tracxn

Resources:

• Joby Aviation website
• Joby Aviation Press Release, Blog Posts, Media Coverage web page
• Joby Aviation Facebook
• Joby Aviation Twitter
• Joby Aviation YouTube
• Joby Aviation Instagram
• Joby Aviation LinkedIn
• Article: Joby Delivers, Vertiflite, November/December 2023
• Article: Hydrogen Begins to Take Off, Vertiflite, July/August 2024
• Video: Flying 523 Miles, Emissions-Free: Joby's Hydrogen-Electric Demonstrator, Joby Aviation, July 11, 2024
• Article: Joby Beats Range Target For Hydrogen-Electric Air Taxi Demonstrator, Aviation Week, July 11, 2024
• Article: Joby completes ‘landmark’ 523-mile hydrogen-electric VTOL flight, Vertical Magazine, July 11, 2024
• Article: Joby demonstrates potential for emissions-free regional journeys with landmark 523-mile hydrogen-electric flight, Joby Aviation, July 11, 2024