Electric Planes — They Can Happen!

Electric Planes — They Can Happen!

Hi! I’m Jim Felder. I work at the NASA Glenn Research Center and this summer I m leading a team of students examining an all-electric regional aircraft. I’m Mike Romanko. I’m Rebecca Navarro I’m Nomita Vazirani And I’m Raul Rios and this is what we ve been working on all summer. Every day 2 million passengers board flights within the U.S. Planes take off once every 3 seconds and burn large amounts of fuel. In fact, airlines spent 209 billion dollars on fuel alone in 2012, and it is estimated that fuel comprises a third of airline operating costs. One avenue that is being pursued to lower fuel consumption and emissions is the use of electric aircraft. Electric planes are already being flown on a small scale using Lithium-polymer batteries. In order to spur research in this area, NASA announced the Green Flight Challenge with the goal to fly 200 miles using less than a gallon of fuel per passenger. The winner was the Pipistrel Taurus G4 with 2 passengers and a fuel efficiency of over 400 miles per gallon. To further this branch of research we aim to model a 50-passenger electric plane with a range of 500 nautical miles. We started by conducting background research involving relevant paper studies going over previously investigated technologies, such as hybrid-electric and turbo-electric propulsion. These methods of incorporating electricity involve either two power sources, a gas breathing engine and batteries, or the standard engine being mounted to a generator, converting the energy into electricity to be distributed. Corporations such as Boeing and ES Aero have already looked into these technologies for large capacity concept airplanes. We wanted to take this a step further and go all-electric on a smaller aircraft. For our baseline model, we used the ATR-42 600 series, which seats 49 passengers and has two Pratt and Whittney turbopropellers, each with a max rating of 2800hp. To create our all-electric airplane, we will strip the ATR-42 of its engines and fuel and replace them with our electric propulsion system and power sources. To model this propulsion system, we used the Numerical Propulsion System Simulation (NPSS) to simulate and optimize the electric motor and propellor, including the inverter and all associated losses. We use aggressive predictions for technological improvements in power and energy densities. We also added improvements to our airframe design such as wing-tip propellers and distributed propulsion. The distributed propulsion allows more air to go over the wing, letting us resize it for max efficiency. The wing tip propellers counter any vortices that form on the tip due to aerodynamic effects, thereby reducing the induced drag on the plane (this is a good thing!). The result of our research is an analysis code that calculates the range for an all-electric aircraft. The analysis code takes in inputs that include the aircraft size, weight, and aerodynamic characteristics, as well as the stored energy in the batteries or flywheels. The code first analyzes the takeoff, climb, descent, and landing segments and calculates the energy used. It also calculates a balanced field length, which is a minimum runway length for takeoff. The cruise segment is then analyzed, with all remaining stored energy, minus some for reserves, being used to determine the cruise range. The final output is a total possible range in nautical miles. Here are some results from our code analyzing an all-electric version of the ATR-42 using batteries and flywheels as power sources. The horizontal and vertical axes represent range in nautical miles, and payload in pounds. The black line represents a fully loaded aircraft with passengers and luggage. Using lithium sulfur batteries with projected performance in 30 years, our aircraft has a maximum range of about 250 nautical miles. These next lines show the higher performing lithium air batteries, reaching a maximum range of about 390 nautical miles in 30 years. The next added lines show flywheels, with an expected range of 500 miles in 30 years. The next plot shows these results compared to the current fuel burning baseline aircraft. Fully loaded, we are close to its maximum range of 800 nautical miles. With lighter payloads, much longer ranges are possible, showing the true limitation of an all-electric configuration compared to a fuel burning one; however this is irrelevant to us, since regional aircraft predominantly fly fully loaded, and routes shorter than 500 nautical miles. This open vehicle sketchpad model of our aircraft shows our implementation of distributed propulsion and wingtip propellers to our baseline aircraft. Due to the novelty of this leading edge technology, the validity of the results of this feasibility study is difficult to determine. Very little has been done before with a specific emphasis on all-electric commuter aircraft technology. However, our study can be compared to the original ATR 42-600 airplane when modeled in FLOPS, a NASA flight optimization software. We can also make sure we are meeting core federal aviation requirements, such as requirements for minimum climb rates in engine out scenarios. Our study provides certain advancements that may help the development of all-electric aircraft. This includes the first simulation of an all-electric propeller in NPSS. Our code can also establish a basis for determining the feasibility of electric aircraft with a sensitivity analysis of various technological advances. In conclusion, our study has taken an ATR-42 600 airplane and retrofitted it to implement all-electric technology. To increase its efficiency, distributed propulsion and wing tip propellers were implemented. Results from MATLAB and NPSS have determined that it is possible to achieve at least a 500 nautical mile range using expected technological advancements in the next 30 years. More work is yet to be done to optimize our design and show it can be feasible in less than 30 years. We would like to thank James Felder, Mark Moore, Karl Geiselhart, Craig Nikol, Ruben Del Rosario, Tom Benson and our colleagues in the Aeronautics and Space Academies.

Eugene Islam

1 thought on “Electric Planes — They Can Happen!

  1. Great work, guys! The industry is overdue for a replacement for the metro23 and similar sized aircraft, have you considered the 19 seat class?

Leave a Reply

Your email address will not be published. Required fields are marked *