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Do electric planes make any difference in terms of noise? When an electric vehicle is in motion most of the noise I can tell are from the tires. A electric pow

Do electric planes make any difference in terms of noise? When an electric vehicle is in motion most of the noise I can tell are from the tires. A electric powered propeller plane would most likely still have most of its noise generated by the propeller, not the internal combustion engine. I presume the same is with jets.

bdamm 6y ago
High torque at lower RPMs is still an untapped potential of electrification for aviation. Having more options for placement of propeller (behind the rudder, for example, where a larger and slower propeller could be placed) is huge. NASA is also experimenting with many small propellers placed ahead of the wings which can result in higher efficiency at cruise, but unfortunately doing their most work when the plane is flying slowest (just before landing). We'll see! But many exciting possibilities.
jillesvangurp 6y ago
Yes in several ways: - No noise when idling and more fine grained control over power. You can't tell apart a plane that is idling from one that is completely off with electric. Some turbo props on the other hand provide so much thrust when idling that you need to be on the brakes or it will start moving to quickly during taxiing. So, that amounts to a lot less noise for electrical planes while the plane is on the airport (i.e. where noise matters the most). - Not all propellers are made the same. They are generally matched to torque and rpm that can be provided by the engine. With an electric engine you'd have a wider range of both as the engine torque and rpm are more easily controlled. That means you can optimize for performance, noise, or both more easily. - Generally propellers get noisy when their tips break the speed of sound. Bigger propellers mean this happens at lower RPM. Smaller propellers can spin faster without having their tips breaking the sound barrier. Electrical engines can be small and light; meaning that you can choose to have a lot of smaller, less noisy ones instead of the big noisy ones. Also, because they can deliver more torque, you can increase the number of blades on the propeller to deliver more thrust and power at lower rpm (at the cost of more drag). - The frequency of the noise matters too. High pitched noise doesn't carry very far. Low pitched noise can be heard miles away. Like the noise of tonnes of kerosine being burned when a big jet takes off. Not a thing with electric. Big combustion engines can be similarly noisy. It's part of what makes them sound so exciting. You are right they won't be whisper silent but they will be a lot more silent overall, and noisy far less often (only when they need to; basically during take off).

bdamm 6y ago

High torque at lower RPMs is still an untapped potential of electrification for aviation. Having more options for placement of propeller (behind the rudder, for example, where a larger and slower propeller could be placed) is huge. NASA is also experimenting with many small propellers placed ahead of the wings which can result in higher efficiency at cruise, but unfortunately doing their most work when the plane is flying slowest (just before landing). We'll see! But many exciting possibilities.

jillesvangurp 6y ago

Yes in several ways: - No noise when idling and more fine grained control over power. You can't tell apart a plane that is idling from one that is completely off with electric. Some turbo props on the other hand provide so much thrust when idling that you need to be on the brakes or it will start moving to quickly during taxiing. So, that amounts to a lot less noise for electrical planes while the plane is on the airport (i.e. where noise matters the most). - Not all propellers are made the same. They are generally matched to torque and rpm that can be provided by the engine. With an electric engine you'd have a wider range of both as the engine torque and rpm are more easily controlled. That means you can optimize for performance, noise, or both more easily. - Generally propellers get noisy when their tips break the speed of sound. Bigger propellers mean this happens at lower RPM. Smaller propellers can spin faster without having their tips breaking the sound barrier. Electrical engines can be small and light; meaning that you can choose to have a lot of smaller, less noisy ones instead of the big noisy ones. Also, because they can deliver more torque, you can increase the number of blades on the propeller to deliver more thrust and power at lower rpm (at the cost of more drag). - The frequency of the noise matters too. High pitched noise doesn't carry very far. Low pitched noise can be heard miles away. Like the noise of tonnes of kerosine being burned when a big jet takes off. Not a thing with electric. Big combustion engines can be similarly noisy. It's part of what makes them sound so exciting. You are right they won't be whisper silent but they will be a lot more silent overall, and noisy far less often (only when they need to; basically during take off).