Bell’s new helicopter may look but it could reduce accidents and noise
1–10 of 14 posts
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#2I guess it must be a stealth helicopter as well
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#3The London Air Ambulance use helicopters with NOTAR (https://en.wikipedia.org/wiki/NOTAR). It's really noticeable how quiet they are compared to other helicopters. They also often land and takeoff on the street - which is pretty cool to encounter on your morning commute. https://www.youtube.com/watch?v=jHsd-YShYds
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#4My experience with computer fans is the smaller ones are much (much) noisier than larger ones moving the same amount of air (because they have to spin faster). Unclear why these are quieter - is it just the electrical power? From the article it seems like they have better control of the speed so can turn them off on the ground, so perhaps they're only quieter in some situations.
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#5My experience with computer fans is the smaller ones are much (much) noisier than larger ones moving the same amount of air (because they have to spin faster). Unclear why these are quieter - is it just the electrical power? From the article it seems like they have better control of the speed so can turn them off on the ground, so perhaps they're only quieter in some situations.
I thought the article explained it quite well:
1) somewhat counterintuitively, in small helicopters the tail rotor can be actually louder than the main one
2) with traditional design the rear rotor HAS TO spin if the main rotor is spinning
3) with this design the rear rotor can stay still, and actually as the article points out at speed you don't have to use it as the air generates enough force on the tail to keep the helicopter straight so to speak, so the entire machine should be quiter in flight.
4) and finally yes, you can keep the rear rotor still on the ground which is safer for ground crews and quiter at the same time
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#6I guess it must be a stealth helicopter as well
Ducted tail rotors are used on some stealth helicopters...but no, it's not.
Some basics: https://en.wikipedia.org/wiki/Stealth_helicopter
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#7Title is borked
Edit: Also from 2020, not really "new".
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#8Title is borked Edit: Also from 2020, not really "new".
The helicopter looks, but it can also hear, now that the noise is lower.
Re: Bell’s new helicopter may look but it could reduce accidents and noise
#9My experience with computer fans is the smaller ones are much (much) noisier than larger ones moving the same amount of air (because they have to spin faster). Unclear why these are quieter - is it just the electrical power? From the article it seems like they have better control of the speed so can turn them off on the ground, so perhaps they're only quieter in some situations.
I'd guess you're mostly correct. OTOH, though these fans could easily cost ~1,000X more than a computer fan. And that extra $$$ might unlock some pretty fancy noise-reduction technologies.