The World's Fastest Electric Airplane

this episode is brought to you by brilliant on november 16 2021 an experimental aircraft called the spirit of innovation designed by rolls royce would record an average speed of just under 556g kilometers an hour or 345 miles per hour over a three kilometer span in subsequent testing a peak speed of 623 kilometers an hour or about 387 miles per hour would then be achieved by modern aviation standards these velocities aren't particularly noteworthy however what makes them a breakthrough is in how they were realized the spirit of innovation is the world's fastest all-electric aircraft [Music] partially funded by the uk's airspace technology institute the spirit of innovation represents a huge leap forward in electric aviation propulsion research it surpassed the previous record set by the siemens e-aircraft extra 330le aerobatic aircraft in 2017 by over 213 kilometers an hour or 132 miles per hour and it also climbed over 60 seconds faster to 3000 meters or about 10 000 feet this speed increase over such a brief period of time was unprecedented in the history of aviation record attempts highlighting the rapid pace at which the aerospace industry is being electrified the spirit of innovation is part of the cell or accelerating the electrification of flight project a joint program spearheaded by rolls-royce and partially funded by the uk government to bring together bleeding-edge technologies and electric propulsion for flight in addition electroflight an aviation startup that specializes in energy storage and uk electric motor and controller manufacturer yasa limited were also major contributing partners on the project the spirit of innovation is designed around an existing airframe that was already known for breaking records the sharp nemesis nxt is a us-designed carbon fiber two-seat single-engine low-wing retractable gear kit aircraft specifically designed for ear racing as designed the aircraft is powered by a highly tuned lycoming tio 540 nxt thunderbolt 6-cylinder engine producing around 400 horsepower on july 30th 2008 the sharp had set a class world record clearing a three kilometer course at 573 kilometers an hour or about 356 miles per hour by september the following year it would hit 653 kilometers an hour or about 406 miles per hour becoming the first home built aircraft ever to exceed a 400 mile per hour average race speed in may 2018 two nemesis airframes were procured and delivered to electroflight at gloucester airport with one being designated for test flights and the other for ground testing the lycoming engine was replaced by three electric motors and the fuel tank by three battery packs combined the battery packs motors and control equipment were similar in weight to the existing power plant however this fully electric system was now capable of outputting around 530 horsepower continuously and almost 1 000 horsepower in bursts among the many challenges of the conversion faced by the a cell team was complications with managing weight distribution throughout a flight while the electric motors were lighter than the original engine the battery packs remain the same weight as they discharged by comparison in a conventional aircraft the overall weight is reduced as fuel is used up to compensate for this the aircraft was converted to a single seater to reduce weight further though at the cost of moving the center of gravity slightly forward because the battery packs took up a large portion of the aircraft keeping both their weight and volume to an acceptable range proved to be one of the main design challenges described as a flying battery with an aircraft attached the spirit of innovation's propulsion system represents a complex juggling act between weight heat and power usage traditional electric vehicle battery pack designs are far too heavy for aviation use so the accel team looked to formula e formula e is the premier single seater motorsport championship for electric race cars and it proved to be the perfect source for innovations in lightweight battery packaging ultimately a battery pack designed around 18 modules each containing 120 cylindrical lithium cells was chosen the cell dimension utilized was the popular 18650 unit that is based on nickel magnese cobalt chemistry within each module the cells are closely packed and a liquid cooling system composed of a cell contacting cooling plate was developed that circulated a water glycol mixture throughout them each module produced 120 volts with a capacity of four kilowatt hours and were capable of fully discharging in a little over three minutes when combined into a battery pack these 18 modules resulted in a 720 volt battery with a capacity of 72 kilowatt hours giving the entire three pack propulsion system a capacity of 216 kilowatt hours employing techniques used by formula e teams to reduce packaging to battery cell weight ratio the accel team had designed a special containment system for the batteries that used portuguese cork for installation and also served as a structural part of the aircraft from this the entire 450 kilogram battery compartment was able to contain a little over 300 kilograms of battery cells by comparison in most electric cars this weight proportion of cells to packaging structure is typically closer to a ratio of one to one the a cell battery pack comes out to a specific energy of 168 watt hours per kilogram making it the highest energy density battery ever used on an electric aircraft though it is similar in density to the battery packs found in most electric cars under cruise conditions it's estimated that this battery system is capable of a flight range of up to 320 kilometers or about 200 miles however battery technology is still a long way from the 500 watt hours per kilogram needed to compete with traditional jet propulsion aircraft for commercial flights designing the propulsion unit for the spirit of innovation was also another major hurdle for the accel team not only must the electric motor be compact and powerful but also possess a high degree of reliability and the ability to tolerate failures for aviation use because no single electric motor was commercially available that would meet these requirements the team decided on a propulsion configuration composed of a stack of three yasa 750r axial flux electric motors coupled by a single shaft running through them the shaft drives a single three blade propeller spinning at 2400 rpm axial flux motors have spinning rotors that are thinner but larger in diameter than conventional radial motors that turn alongside the stator rather than inside it this larger radius delivers 30 percent higher torque density for the same permanent magnet and copper winding provision as a conventional radial motor yas's motor topology known as yokeless and segmented armature further enhances the design with the removal of the stator yoke reducing the mass and increasing power density for the more yasses armature winding consists of separate segments ideally suited to mass manufacture with minimal application specific engineering capable of operating at near 95 efficiency the yaser 750r motor proved to be extremely rigid and easy to integrate coming in at just 98 millimeters or just under 4 inches in axial length however while the yasa 750r can generate 790 newton meters or about 580 foot-pounds of peak torque its peak power output is limited to 250 kilowatts or about 335 horsepower at 3250 rpm using three of these motors in tandem not only met the power requirements of the acell team but it also offered redundancy against motor failure while the entire triple motor system weighed just 111 kilograms or about 244 pounds it was capable of generating around 750 kilowatts or 1000 horsepower though continuous total power is limited to around 210 kilowatts or about 280 horsepower due to thermal constraints unlike road-going vehicles aircraft require relatively larger amounts of continuous power simply to cruise for an electric aircraft this creates safety concerns as the high wattage draw combined with the density of the propulsion system's packaging generates significant amounts of heat additionally the failure mode of the batteries must be accounted for lithium-ion batteries can catch fire and easily trigger a domino effect leading to a disastrous thermal runaway in order to manage the temperature of the battery packs and the motors two actively managed independent liquid cooling systems with four coolant pumps in total were fitted to the aircraft that funneled heat absorbed through the battery cooling plates and the motor's internal cooling passages to a side mounted radiator within the battery pack each individual cell was fitted with both voltage and temperature sensors this robust sensor array not only drove the thermal management system but also served as a safety mechanism providing the pilot information on the health of the battery as well as alerting to potential failure conditions in the event of catastrophic battery failure the thermally insulated containment structure is designed to be fireproof making use of a purging mechanism that maintained an inert argon atmosphere within it this system also vents any built up gases that are generated within the compartment in addition to the motors and the battery packs the aircraft also required a power distribution system control hardware and electronics to manage the nearly 20 000 onboard sensors this was all housed within an avionics bay fitted directly behind the battery packs with the exception of the motor controlling inverter being mounted near the cooling system's radiator because the majority of the aircraft's control systems avionics and the cooling system run on low voltage power the power distribution unit also contained multiple redundant low voltage power supplies before flight testing of the spirit of innovation an extensive series of ground tests were conducted on one of the sharp kits constructed as a wingless static test aircraft known as the ion bird by september 2020 over 122 hours of ground tests were performed on the test rig with a strong emphasis on proving the reliability of the battery system in testing the battery packs are subjected to abuse to the point of failure and their behavior recorded across the anticipated envelope of flight operation this allowed the team to determine a strategy for extracting the maximum possible performance from the battery system for the flight testing on september 15 2020 rolls royce chief test pilot phil o'dell flew the spirit of innovation for the first time while the flight lasted just 15 minutes it achieved the speed of kilometers per hour or 210 miles per hour over the next few weeks around 30 15 minute flights were conducted with each gradually increasing flying speeds as the functionality of the propulsion system was validated it was soon discovered that the cooling systems performed beyond what was expected from ground testing due to the addition of the ram air effect in flight as speeds increased rolls royce had to make use of a spitfire as the chase plane to keep up with the electric aircraft because the aim of the acell project was to fly at high speeds the batteries were designed to provide a high power output for a short period of time most flights consisted of 7-8 minutes of high-speed flight near peak power with the remaining capacity reserved for landing and emergency use while odell described the aircraft as being not very different to fly than the existing aircraft he was familiar with its electric propulsion system did present some unique characteristics because the motors did not need to idle the propellers would completely stop when taxiing confusing traffic controllers though once in the air they provided thrust in a very linear and responsive manner unlike any combustion engine in between flights the battery packs could be recharged individually within an hour though this was primarily limited by the electrical infrastructure that the team operated from it's estimated that this charge time could be reduced to as little as 30 minutes beyond top speeds the a cell program also provided a great deal of insight into the behavior of high-capacity batteries in aviation use unlike electric cars high-voltage batteries in aviation use are at higher risk for arcing from corona effect due to the lower air density at higher altitudes as operating voltages are increased to reduce component weight the greater this risk while this risk can be mitigated by cable separation this becomes difficult in smaller airframes future electric aircraft designs may need to adopt a staged operating voltage system that can balance the risk of arcing with the aircraft's size power requirements and altitude additionally electric aircraft subject their batteries to far more frequent full discharges than road electric vehicles which drastically affects battery life for example the accel team had determined that their batteries can only be recharged from 500 to 1500 cycles before they degrade beyond the safe limit for flight airports will also need to be equipped with higher capacity battery charging infrastructure to practically operate even small electric aircraft the experience gained from the accel project is expected to pivot rolls royce into the development of complete electric propulsion systems for commercial electric vertical takeoff and landing air taxis and larger electric powered commuter aircraft currently partnerships with several electric propulsion aircraft projects throughout europe are being explored with several of these projects even looking towards transitional technologies to power large aircraft such as hybrid electric systems advanced gas turbine engines and sustainable aviation fuels all with an encompassing goal of bringing aviation into a new era of electric flight one of the more fascinating challenges of fitting an electric propulsion system into an existing airframe isn't in the propulsion system's operation but rather how drastically it changes the flight characteristics of the aircraft engineers must evaluate decisions that span across a multitude of disciplines to hone in on a balance that results in an effective design scientific thinking in a multi-faceted approach is a critical part of engineering and with brilliant building critical thinking skills to attack design challenges has never been easier brilliant is my go-to tool for diving head first into learning a new concept it's a website and app built off the principle of active problem solving because to truly learn something it takes more than just watching it you have to experience it with this in mind brilliant has been tirelessly revamping their courses to introduce even more interactivity and with their recently updated scientific thinking course you'll be able to examine the world around us through the eyes of scientific principles in this course you'll dispense with number crunching and mathematics in search of something more useful physical insight you'll be able to discover the truth for yourself using interactive exercises that let you experience the principles of science firsthand with brilliant you learn in depth and at your own pace it's not about memorizing or regurgitating facts you simply pick a course you're interested in and get started if you feel stuck or made a mistake an explanation is always available to help you through the learning process if you'd like to try out brilliant for free and get 20 off a year of stem learning click the link in the description below or visit brilliant.org forward slash new mind you

Channel: New Mind

Views: 792,512

Keywords: electric aircraft, spirit of innovation, rolls royce, accel, siemens eaircraft, eaircraft, lithium powered flight, electric aviation, electric flight, fastest electric aircraft

Id: GsXGJ1O3ccQ

Length: 16min 29sec (989 seconds)

Published: Sat Jan 15 2022