Good Point PN, I do, bit of a diaphragm rattler is the beast. My dogs get restless shortly before even that!:uhoh:

Many moons ago (zzz) I had the privilege to fly the mighty BV234, and during training we were told that during some oil ops in Alaska/N Slope someone appeared at the heliport to meet a colleague inbound on one of the 234s. The unmistakable slap slap slap duly materilalised and our friend went outside into the minus 20deg cold to watch the arrival. After ten minutes or so the Ops bod got concerned and went out to tell the visitor, who was puzzled that the machine was not yet in sight, that they'd just called in their eta in 40 minutes time (ie nigh on 100 miles), and wouldn't he be more comfortable indoors?

My experience in more temperate climes was that the noise was very variable from arrival to arrival, and seemed to be related to small changes of wind direction or a/c heading - ie the loud stuff seemed very directional. At certain power settings (suspect in cruise-speed descent) the cannon-fire slap was very evident, though the Bell 214ST was capable of just as much, if not more in certain regimes of descent.
Again, huge broad blades slapping thru the vortices.

But Chinooks not audible seconds away? Hmm.

Around this part of the world they are clearly audible about five times earlier than the Apaches, Merlins and occasional Sea Kings that follow the ridgeline I live on.

Bless'em!

The cab may have been amazingly well rotor-tuned (unlikely - it's difficult to achieve), or could have been flying a little more slowly than the others you have heard, which quietens things down, but only a little. Poor viz, or a concealed approach may have meant the cab was being flown nearer to 80 knots rather than the more usual 120-135 knot cruise. Pure speculation, of course. If the route they were taking was to the south of you, the northerly drift would also affect the noise levels, as has already been suggested.

Apparenty Odious F&L are adding anti-knock to the F34.

They dare not add too much though in case the crews start to think they are chubby Benson mates flying quiet lttle plastic pigs, which would result in them ordering extra rats and more importantly, turning down any serials that require more than a Brigadier and his best chum from being lifted to a garden party.:}

Anyway, the Kamov Ka-26 and its derivatives beat the Chinook it into a cocked hat in the noise stakes. Replacement windows anyone?:uhoh:

As for noise complaints about the Wokkas around here, I point the locals at Middle Wallop.:E

Joking apart, most folk have seen the news footage of CasEvacs and accept the need to train low at night. Some of them also think that if the local HEMS is busy, the Wokkas/SAR Sea Kings will come to get 'em instead.

Theres some interesting replies coming in about Chinook blade slap noise. It will be almost impossible for me (who started this thread) to dispose of any reply v my hearing.

I accept my limited knowledge in this field will seem trivial to most, but as Razor61 and I regularly get overflown by Chinooks, our hearing has become tuned into the sound/frequency/decibel etc. The last 2 months i just find myself thinking, the Chinooks sound very quiet compared to before. And thats with 2 months of Chinook traffic at mostly low level and running in from the west and east in very differing weather conditions day and night.

They just sound different somehow!! Never mind..everyone, have a spiffing day and i thank you for your interest.

Coley

I remember when we got the first one and our exchange Auzzie pilot D**** W****x was on the ops desk when the phone rang from some discruntled farmer complaining that our new helicopter was scaring his horses/cows/sheep/old lady and he replied to him.... "well they better get used to it soon as there are another 30 odd on the way and they are going to be around for the next 30 to 40 years".... :D

Wooka Wookas, Wokka Wokkas or Bop Bops?
 

My younger son's first word for anything that flew was 'Bop Bop', thanks to the Chinooks passing over.

If you lived under their flightpath you would soon know which are Chinooks and which aren't, long before you see them.

We do get the occasional one which doesn't sound right though. It's as if one blade is at a different pitch or something.

I love seeing them, but some saddo in our estate notes down the time and direction of each one and regales it all at the residents association meeting each year. Some people should get a life!

Mechta, that's the blade tape coming off. MGD or one of the others can explain better what blade tape does!

My 4 1/2 year old daughter can clock a Chinook from over the horizon thanks to her excellent hearing and even if she can't see it coming she'll let me know so I can look in the directions she's not looking in to make sure she doesn't miss it.
She managed to upset a member of Chinook crew at the Leuchars airshow a couple of years ago by telling him "Its not a pretty helicopter, its a Chinook" much to his consternation, especially when he found that she was only 2 1/2 at the time! My daughter the spotter :8