Powerful helicopter sound Bell 407 OK-ALB

I just love this deep rich harmonic sound with some phase modulation! I've tried to capture it the last month and half and finally managed it. There's quite a lot of air traffic (planes and helicopters) here in Prague - Písnice, but most of the helicopters have poor sound.

It is Bell 407 helicopter OK-ALB in black/beige color operated by Blue sky service (http://www.ok-alb.com/). Flight MODE-S code A37A9EA. First it approaches with the deep harmonic sound, then it flies by overhead with a more noisy mid-spectrum sound.

Recorded on Zoom H4nSP, this time with 4GB SD card which has far lower startup time than 32 GB one (like 12 secs compared to more than a minute).

Besides the helicopter itself there are some birds singing, insects buzzing and some rumble from the wind (I didn't manage attach the deadcat windshield so quickly).

Basic frequency: ~ 33.87 Hz.

Original filename: 160703-000.wav