X-57 Maxwell

NASA’s X-57 ‘Maxwell’ is the agency’s first allelectric experimental aircraft, or X-plane, and is 

NASA’s first crewed X-plane in two decades. The 

primary goal of the X-57 project is to share the 

aircraft’s electric-propulsion-focused design and 

airworthiness process with regulators, which will 

advance certification approaches for distributed 

electric propulsion in emerging electric aircraft 

markets.

The X-57 will undergo as many as three configurations as an electric aircraft, with the final configuration to feature 14 electric motors and propellers 

(12 high-lift motors along the leading edge of the 

wing and two large wingtip cruise motors). 

The X-57 team is using a “design driver” as a technical challenge, to drive lessons learned, as well 

as best practices. This design driver includes a 500 

percent increase in high-speed cruise efficiency, 

zero in-flight carbon emissions, and flight that is 

much quieter for the community on the ground. 

Produced by converting an existing general 

aviation aircraft

The X-plane is being built by modifying a baseline Italian Tecnam P2006T to be powered by an 

electric propulsion system. The advantage of using 

an existing aircraft design is that data from the 

baseline model, powered by traditional combustion 

engines, can be compared to data produced by the 

same model powered by electric propulsion. 

The project is being executed through four phases, 

referred to as “modifications”, of testing.

Modification I

The first phase of investigating the potential for 

electric propulsion included defining the requirements of the research, along with systems analysis, 

design, and a number of tests, both in the air and on 

the ground. 

LEAPTech

One of the earliest evaluations during the Modification I phase included ground validation of the 

distributed electric propulsion high-lift system. The 

Leading Edge Asynchronous Propeller Technology 

testing, or LEAPTech, performed this validation on 

the Rogers Dry Lakebed at Edwards Air Force Base 

in California. The project was a collaboration between NASA and California companies Empirical 

Systems Aerospace of San Luis Obispo, and Joby 

Aviation of Santa Cruz.

An experimental electric wing, named the Hybrid 

Electric Integrated Systems Testbed, or HEIST, 

was hoisted atop a heavily modified big rig, which 

drove at speeds close to 80 mph to simulate the effects of a wind tunnel. The wing was outfitted with 

Artist concept of the X-57 Maxwell in flight.
X-57 Maxwell 2 NASA Facts

18 electric motors and propellers, which ran simultaneously 

during the lakebed runs. 

The tests, performed in May 2015 showed that the motors produced a total of 300 horsepower. It validated that the airflow from 

the distributed 18 motors generated more than double the lift of 

the unblown wing.

Baseline Tecnam Data Collection

In 2015, NASA pilots and engineers also performed test flights of 

a production-instrumented Tecnam P2006T in the skies above and 

around Edwards Air Force Base. The purpose of the flights was to 

collect data, such as lift, drag, cruise efficiency, energy usage and 

ride quality.

The X-57 is a P2006T integrated with an electric propulsion system, which will be flown to gather data from similar flights. The 

two sets of data will be analyzed and compared, helping NASA’s 

X-57 team to meet its design driver of validating the ability of 

distributed electric propulsion to improve efficiency.

Modification II

The project’s second phase includes several milestones for X-57. 

In addition to continued systems testing and validation, Mod II 

marked the beginning of physical integration of X-57 itself into 

its earliest stage as an electric aircraft. 

Battery Redesign and Validation

As an all-electric experimental aircraft, X-57 will be powered 

through the use of lithium ion battery systems. In order to 

implement these systems as safely as possible, NASA first had 

to validate that the batteries could safely power an entire flight 

profile, and demonstrate the system’s ability to isolate any rapid 

temperature increase to prevent it from spreading, and escalating 

into a fire – an event known as a “thermal runaway”. 

NASA engineers achieved this milestone following a system redesign in 2017, allowing the batteries to be fabricated, and ensuring 

a safe environment for the test program. The successful battery 

redesign was shared publicly, providing an immediate benefit to 

the industry as a result of the research.

Simulator

Pilots and engineers developed and began flying an X-57 simulator at NASA’s Armstrong Flight Research Center in California, 

designed to feature the specifications of the electric propulsion 

system. The interactive simulator began preparing pilots for 

X-57’s future flight testing phase.

Flight control engineers and technicians at NASA Armstrong developed the simulator to provide a virtual flight experience based 

on what the X-plane itself will actually feel like when it’s in the 

air. The system helps familiarize pilots with the system and makes 

them more adept with reaction times and maneuvers.

Airvolt

Before an experimental electric system could be integrated into an 

aircraft, it had to first be tested and validated. A 13.5-foot tall test 

stand helped NASA researchers better understand the intricacies of 

electric motor systems, and provided validation for the thrust of the 

electric motors. In addition to helping engineers anticipate system 

integration challenges, the stand helped to verify the components of 

electric propulsion.

As early-stage technology is further evaluated, confidence in its use 

for future systems is established. Managing the differences between 

traditional aircraft propulsion and distributed electric propulsion is 

made easier by finding methods of managing those differences.

Initial Electric Retrofit and Testing

The Modification II version of the X-57 looks similar to the baseline 2006T, except the two traditional inboard combustion engines 

are replaced by two inboard electric motors, essentially turning 

the aircraft’s propulsion system electric. 

Ground taxi tests at NASA Armstrong help to examine and 

validate the safety and functionality of the electric system, while 

flight tests will seek to validate the X-57’s electric motors, battery, and instrumentation.

Modification III

Work on the third phase of the project began in tandem with 

Modification II, with the goal of taking the X-57 to a new level of 

experimental electric-powered flight.

High Aspect Ratio Experimental Wing 

Perhaps the most noticeable difference from the X-57’s Modification II configuration is the development and integration of an 

experimental, high-aspect ratio wing. Designed by Xperimental of 

San Luis Obispo, California, the wing features a large reduction 

in area, with wing loading increasing from 17 pounds per square 

foot to 45 pounds per square foot.

The reduction in wing area also contributes to more efficient 

cruise flight through decreasing friction drag. The final Modification IV effort will demonstrate that the high aspect ratio wing 

The integrated experimental testbed reached speeds of up to 

73 mph in data collection to create the effect of a wind tunnel 

on the ground. (NASA Photo/Tom Tschida)
FS-2019-10-109 AFRC

National Aeronautics and Space Administration

Armstrong Flight Research Center

P.O. Box 273

Edwards, California 93523

NASA Facts

with the integrated high lift motor system will allow the X-57 to 

take off and land at the same speed as the baseline P2006T. The 

aircraft will also be less sensitive to gusts and turbulence, leading 

to a smoother flight.

Relocation of Cruise Motors to Wingtips

One of the most critical, and noticeable, elements of the high 

aspect ratio wing is the relocation of the large cruise motors to 

the wing tips. The replacement of 100-horsepower Rotax 912S 

engines with 60-kilowatt motors, developed by Joby Aviation, reduce the weight of each motor and propeller from approximately 

125 pounds to about 57 pounds. 

The much lighter-weight electric motors allow for their relocation 

outboard. By moving the cruise motors from their Mod II inboard 

position to the wingtips for Mod III, the cruise motors recover 

energy that would otherwise be lost in the wingtip vortices.

Nacelles, which are outer casings that can generally act as housing 

for an aircraft’s engine, are also installed along the leading edge of 

the wing where 12 high-lift motors will eventually be positioned.

Modification IV

The final configuration of the X-57 presents the X-plane in its 

full, experimental configuration.

12 Leading Edge High-Lift Motors

The X-57, in its final form of the project, features 12 high-lift 

motors along the leading edge of the distributed electric propulsion wing. Similar to the 18 small motors used during LEAPTech 

ground tests, the high-lift motors are electrically powered to generate enough lift for X-57 to be able to take off at standard Tecnam 

P2006T speeds, even with the high aspect ratio experimental wing.

The high-lift motors and propellers are designed to activate, along 

with the wingtip cruise motors, to get the X-plane airborne. When 

the plane levels out for cruise mode, the high-lift motors will then 

deactivate, and the five propeller blades for each motor will then 

stop rotating, and will fold into the nacelles, so that they don’t 

create unwanted drag during cruise. The two wingtip cruise motors 

will maintain flight during this phase of the flight.

When the time comes to land, the motors will then reactivate, and 

centrifugal force will cause the propeller blades to unfold and create the appropriate lift for approach and landing.

Validation of Environmentally Friendly Aviation

The design driver for X-57 will also seek to reach the goal of zero 

carbon emissions in flight, which would surpass the 2035 N+3 

efficiency goals. Electric propulsion provides not only a five-to-ten 

times reduction in greenhouse gas emissions, but it also provides 

a technology path for aircraft to eliminate 100 Low Lead AvGas, 

which is the leading contributor to current lead environmental 

emissions.

Additionally, since the X-57 will be battery-powered, it can run off 

renewable based electricity, making clear the environmental and 

economic advantages.

Specifications (based on the Mod. IV configuration)

Goal – Help develop certification standards for emerging electric 

aircraft markets.

Design Driver - 500 percent increase in high-speed cruise efficiency, zero in-flight carbon emissions, and flight that is much 

quieter for the community on the ground.

Objectives are to:

• Mod II – demonstrate 3.3x lower energy use at high speed 

compared to original P2006T.

• Mod III – demonstrate 1.5x lower energy use at high speed 

compared to Mod II.

Aircraft Weight – Approximately 3,000 pounds.

Maximum Operational Altitude – 14,000 feet.

Cruise Speed – 172 mph (at 8,000 feet).

Critical Takeoff Speed – 58 knots (67 mph).

Batteries

• Lithium Ion.

• 860 pounds.

• 69.1 kilowatt hours (47 kilowatt hours usable)

Cruise Motors and Propellers (2)

• 60 kilowatt.

• Air-cooled.

• 5-feet diameter propeller.

• Out-runner, 14-inch diameter.

• 117 pounds each, combined weight.

High-Lift Motors and Propellers (12)

• 5-blade, folding propeller.

• 10.5 kilowatts.

• Air-cooled.

• 1.9 foot diameter propeller.

• 15 pounds each, combined weight.