Bell UH-1 Iroquois helicopters have such a distinctive thumping sound and were first used during the Vietnam war. Back in the day the Royal New Zealand Air Force had an active fleet of 13 Iroquois, but retired them in 2016 as they were replaced by NH90 helicopters.
I made these recordings for a feature film back in 2012, with the RNZAF providing the Iroquois for recording at Ohakea Air Base. Note: these recordings are provided at cost: the small charge covers the admin & hosting charges.
Captured and delivered 24bit 96kHz with MKH8040 pair, MKH70 pair, MKH8050 plus an MKH8020 omni for that low frequency thwack!
Note: Cuelist is below.
It was not possible to record onboard, and my record list prioritised what we needed for the film.