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…hearing helicopters constantly overhead as they survey the Olympic Boroughs… …sonic influence into our process is inevitable…  …swinging microphones over our heads as the rest duck and weave underneath imagining their on the run across deserted cities… The source of the noise made by Helicopters are created by several things. The engines can make noise just like any airplane. The transmissions can make a high frequency noise. The destinctive sound of helicopters is the “whop-whop-whop” it makes. This is caused by the rotor blades as it rotates. One reason for this sound is one blade passes and creates a vortex(or whirling tunnel of air) and then the next blade slaps this vortex. Another reason is that each blade must change pitch angle as it rotates around the central mast. When the blade is on one side of the helicopter, it has a high pitch and creates a high lift and therefore a large turbulent vortex. Then as it rotates to the other side of the helicopter, the blade must decrease its pitch angle, sometimes to almost zero angle. This rapid change in high blade angle and low angle causes this blade sounds. Read more: http://wiki.answers.com/Q/Why_do_helicopters_make_noise#ixzz21IbXv6Oo mylifeaspetra: Landningsplatta på taket. Nästan. #helicopter #blue #sky (Taken with Instagram)

…hearing helicopters constantly overhead as they survey the Olympic Boroughs…

…sonic influence into our process is inevitable… 

…swinging microphones over our heads as the rest duck and weave underneath imagining their on the run across deserted cities…

The source of the noise made by Helicopters are created by several things. The engines can make noise just like any airplane. The transmissions can make a high frequency noise. The destinctive sound of helicopters is the “whop-whop-whop” it makes. This is caused by the rotor blades as it rotates. 


One reason for this sound is one blade passes and creates a vortex(or whirling tunnel of air) and then the next blade slaps this vortex. 


Another reason is that each blade must change pitch angle as it rotates around the central mast. When the blade is on one side of the helicopter, it has a high pitch and creates a high lift and therefore a large turbulent vortex. Then as it rotates to the other side of the helicopter, the blade must decrease its pitch angle, sometimes to almost zero angle. This rapid change in high blade angle and low angle causes this blade sounds. 

Read more: http://wiki.answers.com/Q/Why_do_helicopters_make_noise#ixzz21IbXv6Oo

mylifeaspetra:

Landningsplatta på taket. Nästan. #helicopter #blue #sky (Taken with Instagram)