Rolls-Royce Aerospace manufactures jet engines that power many planes around the world. While they are at the cutting edge of technology in terms of efficiency, they also leave behind a lot of greenhouse gas emissions.
The company has been a leader in the development of electric propulsion systems for airplanes to help move the world towards a future of zero emission flight. Getting there will involve many innovations. The main obstacle is that batteries have a much lower energy density per unit weight than jet fuel.
Let’s dig into that a bit. According to JetPack Aviation, a liter of jet fuel has an energy density of 9.6 kWh and weighs approximately 0.8 kilograms. This translates to 12 kWh per kilogram. In comparison, some of the best lithium-ion batteries have an energy density of 265 Wh per kilogram. The net result? Jet fuel has nearly 50 times more energy available per kilogram to power an aircraft than batteries.
But the analysis does not stop there. While jet fuel is energy dense, even the best combustion engines are not very efficient at converting that energy into forward motion. JetPack says the inefficiency of internal combustion means that 1,000 pounds (453.59 kg) of jet fuel produces only about 14 times more horsepower than 1,000 pounds (453.59 kg) of batteries. Much of this wasted energy exits the rear of the engine and ends up in the atmosphere.
The net result is that the âfuel loadâ for an electric aircraft will be much greater than it would be for a conventional jet aircraft. In fact, cramming enough batteries into an airplane to make it fly leaves a very small carrying capacity for cargo and passengers, let alone a pilot.
Rolls-Royce Aerospace has worked hard to develop an electric aircraft capable of flying over 300 mph (or 483 km / h for those who insist on using the metric system), making it the fastest electric aircraft ever built. . This week, the completed aircraft made its first sustained flight. It was in the air for 15 minutes. I’ll leave it to you to convert this to parsecs if you wish. And if you think 15 minutes isn’t that long, remember that Wilbur and Orville Wright’s first powered flight to Kitty Hawk was only 12 seconds and that led to some pretty amazing things.
Rolls-Royce Aerospace says the test flight is “the start of an intensive flight test phase during which we will collect valuable performance data on the aircraft’s power and propulsion system. “, according to Committed. The company claims the single-seater aircraft has “the most powerful battery ever assembled for an aircraft,” but gives no details. It uses a 6000-cell battery with a three-engine powertrain that currently delivers 400 kW (500+ horsepower).
The flight took place about a year after the initially planned take-off and about six months after the taxiing tests. Rolls-Royce is developing an air taxi with aircraft manufacturer Tecnam with the aim of providing an âall-electric passenger plane for the commuter marketâ. She also worked with Siemens and Airbus on another concept of electric aircraft.
The project is funded by the Aerospace Technology Institute and the UK government as a preliminary step towards the creation of all-electric passenger aircraft. âIt’s not just about breaking a world record; the advanced battery and propulsion technology developed for this program has exciting applications for the urban air mobility market and can help make ‘jet zero’ a reality, âsaid Warren East, CEO of Rolls-Royce.
Eviation has already created a production prototype of a 9-passenger electric commuter aircraft with a range of 440 nautical miles (815 km) and a cruising speed of 220 knots (407.44 km / h, 253 mph, or 317 feet per second, if you prefer). United Airlines has also invested in Swedish start-up Heart Aerospace and has ordered 100 of its short-haul electric planes to be delivered by the end of this decade.
Electric flight is coming, maybe not tomorrow, but soon. Batteries with higher energy densities will be the key to unlocking their potential. Air travel accounts for around 7% of global emissions, so anything that reduces the amount of aircraft emissions is welcome. Our children will surely be flying in electric planes and will not find anything remarkable in doing so.
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