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Joby Aviation S4 2.0 (pre-production prototype)

Joby S4

(Photo credit: Joby Aviation)

S4 2.0 (pre-production prototype)
Joby Aviation
Santa Cruz, California, USA

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.

The company combines elements of helicopters and small airplanes, offering benefits that include high reliability, zero emissions, fast flight speeds, quiet operations, lower operating costs, lower costs of maintenance, and enhanced safety features. Their former projects include the Joby S2, Joby Lotus, and Joby Monarch.

Joby Aviation has been relatively secret with its S4 aircraft, but it was derived from the Joby S2 design. Some few computer images of the S4 were presented at the 2nd Annual AHS Transformative Vertical Flight Workshop held at the NASA Ames Research Center in August 2015. At the Vertical Flight Society’s 6th Annual eVTOL Symposium in January 2019, Joby revealed additional information and initial performance details of test flights of scale and full-sized demonstrators. On Jan. 15, 2020, they revealed full scale pictures of their S4 eVTOL aircraft (see above and directly below) and additional specifications about their aircraft, the use of the aircraft and their company.

At the 7th Annual eVTOL Symposium on Jan. 22, 2020, founder JoeBen Bevirt gave a banquet keynote address and gave insights into the history of the company and the air taxi development.

At the US Air Force Agility Prime Launch Event on April 27, 2020, Joby Aviation Executive Chairman Paul Sciarra provided highlights into the company’s flight testing over the past five years, and showed the history of flight testing its subscale model, its four-seat Generation 1 aircraft and its five-seat Generation 2 aircraft, which is now moving through the FAA Type Certification process.

Agility Prime has Joby Aviation Paul Sciarra review their flight testing from 2015-2019 on Zoom April 2020.

Joby Executive Chairman Paul Sciarra briefed at the Agility Prime launch in April 2020.

A July 17, 2020 article on eVTOL.com detailed the air lift transfer by helicopter of the second generation S4 from Santa Cruz to US Army Garrison Fort Hunter Liggett in southern Monterey County on July 7.

A Sept. 25, 2020 Aviation Week article included the first photo of the aircraft in flight (other than a photo in January with it hovering just a few feet off the ground) and reiterated that the original unmanned prototype sized for four seats is referred to as "1.0" and the second aircraft, sized for five seats, is referred to as "2.0" or "second generation."

Sized to carry four passengers and one pilot, it will be capable of operating day/night flights in instrument or visual flight rules up to 150 nm. Although only 21 ft. [6.4 m] long overall, the aircraft has a wingspan of 38 ft. [11.6 m] ...


Subscale S4 prototypes were flown more than 700 times starting in 2015, and in 2017 the company began remotely piloted tests of the first-generation, full-scale “1.0” version. Building on this high-wing, six-propeller configuration, Joby started flight tests in 2019 of the second-generation “2.0” version. Changes included increased gross weight—up to 4,800 lb. [2,177 kg] — and a revised swept-forward V-tail.

Joby says “several hundred” flights have been completed to date, including some with a pilot onboard. Although some testing can be flown remotely, the certified S4 will be piloted to enable integration into the existing national airspace.

Joby Unveils EVTOL Design Details And Certification Plans, Aviation Week Network, Sept. 25, 2020

In October, Joby filed a number of patent applications, with additional details and drawings of the S4 air taxi 2.0.

On Nov. 23, Forbes.com published a pair of articles on Bevirt and Joby. In conjunction with this, Joby updated their website with a number of photos of the aircraft in flight, including one in full transition (unmanned).

Joby Aviation S4 2.0 (pre-production prototype) aircraft design and features
Joby Aviation's S4 2.0 (Generation 2 pre-production prototype) is a five-seater (one pilot and four passengers) eVTOL air taxi aircraft using six tilting propellers which are located on both the fixed high-wing and its V-tail. Four propellers tilt vertically including its entire motor nacelle, and two of the propellers tilt vertically with a linkage mechanism. The aircraft has as very modern and futuristic design with large windows for spectacular views and has a tricycle-type retractable wheeled landing gear. The company reports their aircraft is 100 times quieter than a helicopter during takeoff and landing with a near-silent flyover.

A distributed electric propulsion (DEP) system (leveraged by NASA’s LEAPTech demonstrations) can take the aircraft to speeds of 200 mph (322 km/h) which are powered by lithium-nickel-cobalt-manganese-oxide batteries, providing a range of 150 miles (241 km). The vehicle employs a unified flight control system to reduce pilot workload during the conversion to and from VTOL to horizontal flight mode.

DEP on eVTOL aircraft provide multiple advantages, including greater stability of the aircraft in regular and gusty wind conditions, a much quieter aircraft, no emissions, lower weight, higher reliability, lower cost to operate, more compact, higher efficiency, no start-up or shut-down delay, and safety through redundancy for its passengers. If one or two motors or propellers fail, the other working propellers can safely land the aircraft.

In a demonstration for Bloomberg News, the S4 completed a piloted test flight that included a vertical takeoff, 15 minutes of flight along a 15 mile (24.1 km) course, and a controlled landing." The flight took place in early 2017.

Honors and FAA registry
Joby was honored in May 2018 with the Vertical Flight Society's Paul E. Haueter Award, given for an outstanding technical contribution to the field of VTOL aircraft development other than a helicopter or an operational vertical flight aircraft was awarded to JoeBen Bevirt, the founder and chief executive officer of Joby Aviation Inc., for successfully demonstrating the world’s first high-speed multi-passenger electric VTOL aircraft.

Joby has registered the following aircraft in the FAA Aircraft Registry:

  • The unmanned Generation 1.0 demonstrator has the registration N541JA, model number JAS4-1 and and serial number JAS4-101 ("Joby Aircraft S4, Generation 1, Aircraft 1"). The test vehicle was originally nicknamed "Rachel."
  • The second aircraft — the manned Generation 2.0 prototype — was registered as N542AJ in August 2019 with model JAS4-2 and serial number JAS4-201 ("Joby Aircraft S4, Generation 2, Aircraft 1") .
  • The second Generation 2.0 prototype was registered as N542BJ in March 2021 with model JAS4-2 and serial number JAS4-202 ("Joby Aircraft S4, Generation 2, Aircraft 2").

On an April 14 webinar by IPO Edge, Joby executive chairman Paul Sciarra said that its US Air Force Agility Prime Small Business Innovation Research (SBIR) Phase II Plus contract last year was for Joby to deliver two aircraft to the Air Force in 2021. If awarded a Phase III extension, Joby could deliver 10–30 aircraft for on-base operations.

Funding and partnerships
Joby was initially funded by JoeBen Bevirt, Paul Sciarra and others. Series A and Series B investments reached $130 million USD in 2018. In January of 2017, Joby Aviation received $970,000.00 USD from the Defense Innovation Unit Experimental (DIUx), a Pentagon organization that focuses on implementing cutting-edge technology into the U.S. Military. Joby’s efforts are backed by at least five large investors (Capricorn Investment Group, Intel Capital, JetBlue Technology Ventures, and Toyota AI Ventures). On Jan. 15, 2020, it was announced that Toyota provided Joby Aviation with $394 million USD in funding, bringing the total money raised so far for the company, to a grand total of $720 million USD.

On Dec. 20, 2019, Uber announced that the company had signed a multi-year commercial partnership with Joby Aviation to launch a fast, reliable, clean and affordable urban air taxi service in select markets. Joby will supply and operate the electric air taxis, and Uber will provide airspace support services, skyport infrastructure, connections to ground transportation and customer interfaces through its aerial rideshare network. With this agreement, Joby Aviation becomes the first partner in Uber’s Elevate initiative with a committed timetable to deploy air taxi services by 2023. The company expects the cost per trip, over time, to be in the similar price range of ground transportation.

Flight testing
At the VFS 6th Annual Electric VTOL Symposium on Jan. 29, 2019, Joby noted that the company had "Successfully flown sub-scale and full scale demonstrators" and provided the following details on the S4:

  • Safety assurance in excess of CS-23 cert requirements
  • Unified flight control – extremely simple vehicle operations (SVO)
  • All electric CTOL/VTOL
  • 200 mph cruise speed (322 km/h)
  • 150 mile range (241 km)
  • 100 times quieter than a helicopter

Joby plans on continuing to make prototype aircraft in Marina, California, USA and will use Toyota production facilities to mass produce the aircraft. The company is expecting the Federal Aviation Administration (FAA), USA, to provide certification for their aircraft by 2022 and expect the public to ride-share their aircraft in 2023. The company is also seeking certification for their aircraft in countries around the world. The aircraft will be used for on-demand urban air mobility (UAM), an air taxi, and the aircraft will not be for sale to the consumer.

Manufacturing plant
On Jan. 16, 2020, it was reported by the Monterey County Weekly that an estimated 1,600 high-paying tech jobs could be hired by Joby. Joby Aviation plans to build an eVTOL manufacturing plant in the city of Marina, California (USA), which will ultimately be as large as 580,000 square feet. The manufacturing plant would be approximately 34 miles (55 km) from Joby Aviation’s headquarters in Santa Cruz. Construction for plant is planned to start by April 2021.

Safer flight for urban air mobility
During the Vertical Flight Society’s 7th Annual Electric VTOL Symposium held on Jan. 21-23, 2020, Justin Paines, Chef Test Pilot for Joby Aviation talked about how unified flight control was first developed in 1980. It reduces pilot error and makes it easier to fly the aircraft. All eVTOLs should operate like this, he stated. This is how the Lockheed Martin F-35 combat aircraft controls are made. It means having a good pilot aircraft interface which prevents the pilot from killing himself/herself and his/her passengers.

The idea behind unified flight control is to reduce the ability for the pilot to make errors and crash the aircraft. The argument is not against automation, it’s against partial automation. Pilots can still run out of fuel, run into the ground, hill or mountain, have mid-air collisions and when landing, can have ground collisions. The technology to avoid this pilot error is here and the aircraft will take over the aircraft, when needed, to land safely. The pilot can retake control of the aircraft when the aircraft takes over but it is not be recommended because you’ll probably die. Pilots unable to deal with emergency situations will not crash their aircraft, with this type of technology.

Paines stated that you either you keep things the same or you make it better, it’s called Simplified Vehicle Operations.

  • We must avoid accidents
  • Have simplified Vehicle Operations
  • Lower pilot training costs
  • Keep the pilot from killing himself and his passengers
  • Joby believes the UAM community will lead the way here

Joby's demonstration simulator
Guy Norris, a Senior Editor for Aviation Week, had the opportunity to fly in Joby's demonstration simulator for the Joby S4 eVTOL aircraft, to get a feel for its flight characteristics. Norris wrote about his experience in an Aviation Week, Sept. 25, 2020 article titled, "Catch An Air Taxi? Aviation Week Flies Joby’s EVTOL Simulator". Quoting from the article, "The simulator experience showed that, just as in the F-35, developers have taken away the concerns over flying the aircraft to enable the pilot to focus on the mission. At no point had I become worried about piloting the aircraft or about issues such as stall speed or, as a rotary-wing pilot, an overwhelming workload."

Joby reveals more information, including FAA certification update, battery briefing and more
According to another September 25, 2020, Aviation Week article written by the same author, titled, "Joby Unveils EVTOL Design Details And Certification Plans" the Joby S4 eVTOL aircraft doesn't have the familiar high-pitched sounds a small drone makes. The S4 eVTOL aircraft during its start up and take off, makes a lower-pitched and lower-frequency type sound and when hovering, the sound is much less than the sound of a helicopter. The reporter stated that Joby's claim that their S4 is 100 times quieter than a helicopter appears to be a true statement and the aircraft is almost silent in forward flight.

Bevirt was quoted in the above article as saying, "The number one priority is safety and at a level you see in commercial aviation, which is the safest mode of transportation we have." The second priority is that eVTOL air taxi service has to be very affordable, over time. The article also states that Joby is now 70-80% complete to certify the S4 with the Federal Aviation Administration (FAA). Joby is projecting that certification of the S4 will take place by the end of 2023. The S4 name is not the official name of the aircraft according the above Aviation Week article, the aircraft was designated the S4 for FAA certification purposes.

When it comes to battery technology, Joby has met all range and flight operation parameters with current lithium-ion batteries. Therefore, Joby is not waiting for any type of new battery technology break-throughs at this time because this is not necessary for successful short-haul Urban Air Mobility. The aircraft will be able to make short intracity flights (flights within the same city), intra-suburban flights and intercity (between cities) flights.

Recap of Joby's eVTOL aircraft evolution
Joby Aviation's Monarch personal eVTOL concept was unveiled in 2011. After that, the S2 two passenger eVTOL with 12 tilting and folding propellers was designed. In 2015, a subscale S4 eVTOL was flown over 700 times. In 2017, the full scale S4 eVTOL 1.0 version was being remotely flown with a high-wing and six propellers. In 2019, the S4 eVTOL 2.0 version with several engineering design changes, including the revised swept-forward V-tail, began conducting remote flight testing. Some early piloted hover testing was also conducted by Joby test pilots Justin Paines and James “Buddy” Denham.

Since 2009, the company has focused mainly on the development of their eVTOL aircraft (and also in secrecy) but as of 2020, Joby Aviation is now more focused on certification, initial production, then large scale production and laying the groundwork for commercial operations. The three key pillars for Joby is safety, low noise and affordability for the consumer. As seen the last several paragraphs, Joby is now revealing more about their aircraft, company and future goals and are slowly lifting their veil of secrecy.

Joby will either operate their own aircraft or be in partnership with other ride share companies with Uber. Joby Aviation has stated on their website, they have become the first partner in Uber’s Elevate initiative with a committed timetable to deploy air taxi services. As of the fall 2020, it has been reported that Joby is the farthest ahead of all UAM manufacturing companies and Joby is expected to be in operational service in 2023.

Latest developments
On Dec. 8, 2020,
Joby Aviation announced they will acquire Uber Elevate and that both Uber and Joby will integrate their respective services into each other's apps, enabling seamless integration between ground and air travel for future customers.

The company revealed in a Wall Street Journal article on Dec. 10 that it had received the first ever airworthiness approval for an eVTOL vehicle by the U.S. military, through the U.S. Air Force's Agility Prime program. This means that Joby Aviation is the first eVTOL manufacturer to be certified to fly military personnel. According to the WSJ article, "The Air Force will help accelerate safety analyses by conducting flight tests, pledging to pay for contracts seeking to verify vehicle reliability and generally vetting the capabilities of vehicles through direct and indirect funding of the company."

Agility Prime is a non-traditional program, headed by the U.S. Air Force, to help accelerate the commercial manufacturing of electric aircraft with the ultimate goal of adding hybrid-electric and eVTOL aircraft into the U.S. Air Force's fleet and to also pave the way for all U.S. military branches to begin using eVTOL aircraft.

On Feb. 9, 2021, Joby Aviation announced it had "begun generating revenue as part of achieving another major milestone in the Agility Prime program." According to the press release, the partnership will allow Joby Aviation to gain "key research facilities and equipment, as well as an opportunity to prove out the maturity and reliability of its aircraft years in advance of entering commercial service." In return, the US government will receive valuable data and insight to how eVTOL will perform in real world so the military can determine where and how eVTOL aircraft will help in military operations. It has been reported that because the Urban Air Mobility market (or air taxi market) is projected to be so massive, that it is a matter of national security to ensure the success of U.S. based commercial eVTOL air taxi companies.

The press release also announced that Joby had "agreed to a ‘G1’ certification basis for its aircraft with the FAA in 2020. A ‘G1’ outlines the criteria that need to be met in order for an aircraft to be certified for civil commercial operations, and reaching the milestone marks a key step on the way towards certifying any new aircraft in the US. Joby’s aircraft will be certified in line with the FAA’s existing Part 23 requirements for Normal Category Airplanes, with special conditions introduced to address requirements specific to Joby’s unique aircraft. These special conditions, defined in the ‘G1’ document, are expected to be published in the US Federal Register in the coming months."

“With ten years of engineering and more than a 1000 test flights [including subscale testing, see graphic below] behind us, we’re excited to now be playing a key role in demonstrating the potential of this new sector while giving the US Government a front row seat,” Bevirt said in the press release.

In February 2021, it has been reported in several articles that Joby Aviation now foresees their air taxi service to start in 2024.

On Feb. 11, 2021, eVTOL Magazine reported that "Joby Aviation is close to a deal to go public via a merger with blank-check company Reinvent Technology Partners (NYSE: RTP) in a deal that will value the eVTOL developer at $5.7 billion, according to the Financial Times."

Joby Aviation will merge with special purpose acquisition company Reinvent Technology Partners (RTP) in a deal that provides the Santa Cruz-based eVTOL developer with approximately $1.6 billion in cash, resulting in a post-money valuation of $6.6 billion. The transaction, expected to close in Q2 of 2021, will see Joby Aviation listed on the New York Stock Exchange under the ticker “JOBY” as the company continues working toward its long-term vision of saving a billion people an hour a day via quiet, affordable electric vertical flight.

Each aircraft is projected to cost $1.3 million to manufacture and generate $2.2 million in annual revenue, resulting in a payback period of 1.3 years per plane based on an assumed passenger load factor of 2.3 and approximately 4,500 operating hours per year.

eVTOL Magazine, Feb. 24, 2021

On Feb. 24, 2021, Joby stated they are projecting on having under 1,000 eVTOL aircraft in air taxi service by 2026. Then in 10 years, will have made over 10,000 eVTOL aircraft providing air taxi service in 20 cities around the world and make more than $20 billion USD for the year 2031.

A June 2, 2021 Bloomberg article reveals that Joby Aviation predicts it will begin commercial eVTOL passenger service in 2024 in cities such as Los Angeles, Miami, New York and San Francisco.

On Jan. 6, 2022, Joby confirmed it received a FAA Special Airworthiness Certification and a US Air Force Airworthiness Approval for a second pre-production prototype aircraft in December 2021, as expected. Joby also stated their first pre-production prototype, the Joby S4, has generated 65 terabytes of test data in 2021, flying more than 5,300 miles (8,529.52 km). The company also believes they have flown the longest flight of an eVTOL passenger aircraft to date, at 154.6 miles (248.8 km) on a single charge, the fastest eVTOL flight at 205 mph (330 km/h) and the highest flights of any eVTOL aircraft to date, of over 7,000 feet (1.3 miles) .

In February and June of 2021 and in January 2022, several articles have reported that Joby Aviation foresees their air taxi service to start in 2024.

On Jan. 28, 2022, TechCrunch reported that, "Joby Aviation is seeking permission for a series of high-profile air taxi flights over San Francisco Bay [California, USA], according to documents filed with the FCC and obtained by TechCrunch". During these demonstration flights, the aircraft will be flown by remote control, fly over the San Francisco bay, most likely and would carry no passengers. One of the major tests of these flights would be to test the radio equipment inside the aircraft according to Joby Aviation. In the same TechCrunch article, it was reported the company expects to build at least four S4 eVTOL prototypes and fly approximately 600 test flights over the next two years.

On May 26, 2022, the Joby Aviation announced it received the Part 135 Air Carrier Certificate from the Federal Aviation Administration (FAA) so it can now begin offering on-demand commercial air taxi operations, using conventional aircraft such as helicopters, airplanes or jets. The company plans to start providing air taxi service with conventional aircraft to test and validate their on-demand service technologies.

At this time, the company has not be certified by the FAA to provide air taxi service with its Joby S4 eVTOL passenger air taxi aircraft. However, Joby Aviation is in the process of working with the FAA to make this happen. The eVTOL maker will also need to have a Type Certificate for their eVTOL aircraft (a type certificate signifies the airworthiness of a particular category of aircraft) and a Production Certificate by the FAA to produce their Joby S4 eVTOL aircraft at their manufacturing plant.

First crewed flight of Joby S4 2.0b eVTOL passenger aircraft in New York City, November 12, 2023
The first crewed flight of the Joby S4 2.0b (tail number N542BJ) eVTOL passenger aircraft in New York City took place on Sunday, November 12, 2023. The exhibition flight took off from the downtown heliport in Manhattan marking the first ever eVTOL flight in the city and the first time that Joby Aviation has flown their aircraft in an urban city. Mayor Eric Adams, the mayor of New York City, stated it was the intention of the city to electrify the heliport and for the city to be a global leader of clean and quiet air taxi flight.

Joby Aviation and Delta Airlines are in partnership to provide air taxi service from Manhattan to John F. Kennedy International Airport and  LaGuardia International Airport. By car, the trip from Manhattan to John F. Kennedy International Airport takes approximately an hour and is estimated to take only seven minutes by air taxi service. Joby Aviation and Delta Airlines are working with the Port Authority of New York and the New York City Economic Development Corporation to make this happen.

Expected air taxi service target date
The Joby Aviation S4 eVTOL passenger and cargo production prototype is not expected to be certified for commercial operations until 2025 and the company is planning to start air taxi service in U.S. cities such as Los Angeles and New York City in 2025.


  • Aircraft type: eVTOL passenger air taxi pre-production prototype aircraft
  • Pilot: 1 pilot
  • Passengers: 4 passengers
  • Maximum speed: 200 mph (322 km/h)
  • Range: 150 miles (241.4 km)
  • Propellers: 6 tilt-prop, 4 propellers tilt vertically including the entire motor nacelle, 2 propellers tilt vertically with a linkage mechanism
  • Motors: 6 high performance electric motors
  • Power source; Lithium-nickel-cobalt-manganese-oxide batteries with a cutting-edge battery pack design
  • Wingspan: 35 ft (10.7 m)
  • Length: 24 ft (7.3 m)
  • Weight: 4,000 lb (1,815 kg)
  • Windows: Large windows for spectacular views for the passengers
  • Fuselage: Carbon fiber composite
  • Wing: 1 high main gull wing
  • Tail: 1 V tail
  • Landing gear: Tricycle wheeled retractable landing gear
  • Safety features: Distributed Electric Propulsion (DEP), provides safety through redundancy for its passengers and/or cargo. DEP means having multiple propellers (or ducted fans) and motors on the aircraft so if one or more propellers (ducted fans) or motors fail, the other working propellers (or ducted fans) and motors can safely land the aircraft. There are also redundancies of critical components in the sub-systems of the aircraft. The aircraft can also land like an airplane if necessary and has reserve battery power if there is an unexpected delayed when landing.

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