See the sound a helicopter makes caught on camera

General Discussions
Post Reply
User avatar
Nipuna
Moderator
Moderator
Posts: 2729
Joined: Mon Jan 04, 2010 8:02 pm
Location: Deraniyagala,SRI LANKA

See the sound a helicopter makes caught on camera

Post by Nipuna » Thu Jan 09, 2014 1:13 am

(Image: DLR)
(Image: DLR)
dn24836-1_1200[1].jpg (236.2 KiB) Viewed 4407 times
If you've ever wondered why helicopters make the noise they do, this photo has the answer. For the first time, the way the rotor blades produce sound has been caught on camera.

As a helicopter flies, a vortex forms at the tip of each of the blades, because there is a difference in pressure between the regions above and below them. The noise is caused by blades hitting the vortices created by their neighbours.

A research team led by Markus Raffel of the German Aerospace Center in Göttingen has developed a technique to take pictures of these vortices.

The method uses the same phenomenon that causes air above road surfaces to shimmer on a hot day. Light rays are bent as they travel through patches of air with different densities, and this can be seen clearly against suitable backgrounds.

A series of experiments using different natural backgrounds revealed that the most successful one for spotting vortices was a quarry in the Harz region of Germany. In this confined space, the helicopter had to be photographed rocking just 10 metres above the ground.

The researchers hope their work will help to make helicopters quieter and less prone to vibration.
jaheen100
Corporal
Corporal
Posts: 9
Joined: Fri Jan 03, 2014 4:17 pm

Re: See the sound a helicopter makes caught on camera

Post by jaheen100 » Thu Jan 09, 2014 3:51 pm

How it is possible to catch the sound of helicopter.?
User avatar
Nipuna
Moderator
Moderator
Posts: 2729
Joined: Mon Jan 04, 2010 8:02 pm
Location: Deraniyagala,SRI LANKA

Re: See the sound a helicopter makes caught on camera

Post by Nipuna » Thu Jan 09, 2014 4:00 pm

I have no idea :?

I got this article from New Scientist and posted here.
User avatar
Saman
Lieutenant Colonel
Lieutenant Colonel
Posts: 828
Joined: Fri Jul 31, 2009 10:32 pm
Location: Mount Lavinia

Re: See the sound a helicopter makes caught on camera

Post by Saman » Fri Jan 10, 2014 11:31 am

How it is possible to catch the sound of helicopter.?
Answer is in the article.
The method uses the same phenomenon that causes air above road surfaces to shimmer on a hot day. Light rays are bent as they travel through patches of air with different densities, and this can be seen clearly against suitable backgrounds.

A series of experiments using different natural backgrounds revealed that the most successful one for spotting vortices was a quarry in the Harz region of Germany. In this confined space, the helicopter had to be photographed rocking just 10 metres above the ground.
Post Reply

Return to “General Discussions”