Chinook blades

[coley chaos]

I live in a valley along Red Route 1 in Dorset within which your finest Chinook drivers fly very low level and mostly at night... ive been stumped by the fact that these aircraft can be heard a few miles away as they aproach (in both directions) , even in moderately windy conditions. But lately, the decibels have declined noticeably and the famous wooka wooka noise has now seemigly gone quieter.

Before you all talk about hearing problems/atmospherics... ive been here for over 2 years and have everything fly over with regularity, but the biggest noise change is our friend the Chinook. One went overhead low level last night and wouldnt have known he was there untill 200m away in calm conditions.

New quieter blades for the fleet coming in? or the new model HC3 blades making things quieter? Anyone shed any light or in this case...sound?

Coley.

[dakkg651]

They have replaced the standard blades with those from Blue Thunder.

[charliegolf]

Seven minutes- I checked.

CG

[cornish-stormrider]

Whisper mode on, hit the turbine boost. and where is the 20mm cannon?

[Training Risky]

Maybe you previously heard the loud results of blade slap, as the pilot pulled a lot of power on during a turn or climb? And the quiter noise is as a result of no turning point near your house, hence no blade slap? Or maybe MSD is now higher...?

[coley chaos]

TR...could be, however i have been under these guys for over 2 years of daily (18.00 - 01.00) and know most sounds from various angles and directions. They are deffo quieter these days...

[Runaway Gun]

Do you wear ANR headsets at home?
Have you had a hearing test lately? :ok:

[vernon99]

Well there was one passed here last night around 10-11pm going towards Lyneham just visible in the cloud base, and it was making a right din, strange as it was straight and level. They are not normally that noisy, have they fitted noise generating blades?:}

[whowhenwhy]

Normally the clattering is caused by the level of rejection from mother earth as she tries to push the nasty things away from her. Maybe the quiet flight was as a result of mother earth going down the pub or just giving in and letting the darn thing fly past unhindered! :E

[coley chaos]

Maybe upon reflection im being ultra sensitive...but hearing is 20/20... still insist that the noise has been reduced from WOOKA WOOKA to wooka wooka.... we do get mostly Chinooks through here, with Sea Kings from Yeovilton and Hercules all very low level but the Chinooks have percevably changed. My secretary knows a Sqd Leader at Odiham...perhaps she could find out if its not hush hush, wink wink, say no more!!

Someone must be thinking the same as me!!?:{

[Gainesy]

No difference up here. Mebbe if yer used two Ks instead of two Os it'd be louder?:)

[Razor61]

Get the same around here, normally Hercs, Chinooks and the Yeovilton stuff at night and i can say that i am not hearing the Chinooks half as early as i used to when either low or higher up.
Used to hear them miles off and wait for ages to see them whizz by but now it's short notice, 20-30 seconds atleast compared with much more previously.

Not saying that the Chinooks have a different blade fit but it's certainly less than it used to be in all conditions here. The daily A109's of Castle Air make more racket inbound than Chinooks now

[coley chaos]

Gainsey,

I too feel a little bit titified to of spelt Wokka wrongly...i do appologise, i was obviously typing with my elbows as my fingers were in my ears! :ugh:

[coley chaos]

Razor...

so im not the only one then!! Gods Potatoes, i thought it was all in my imagination for a second or two on this thread!

Theres deffo a decibel change...no real wokka sound for minutes before you see the beast?

Coley

[Razor61]

Well,
Used to be able to hear them very loud for minutes before they came over at night (not so during the daytime due to the noise outside anyway) but at night for sure...
Infact one came past the other night very low but could barely hear it even with the wind coming from that direction. Within seconds of it passing the sound was gone, which is again unusual. Can usually hear it just as long with it retreating!

Must be atmospherics? As i can't recall any of the Chinooks receiving such upgrades to make them quieter.

[coley chaos]

Razor,

Could be...although it does seem a trifle interesting that its been noticable on every Chinook fly over for the last month! interesting, very interesting. Would be very interesting to hear from any "able to confirm Chinook drivers".

[NutLoose]

Change of wind direction may do it carrying the sound away from you.

[MG]

The direction of the wind and the height at which they fly both make a huge difference to the footprint.
There have been no changes to the Chinooks, blades, not since the composite blades of 20 years ago nor do I think that the new 714 engines would make any difference to the blade slap. There's certainly nothing hush hush going on at Odiham, physically nor metaphorically.

Sorry to disappoint.

[Gainesy]

Have you actually seen them? Do you know they are Chinooks? Merlins are just as loud but with about 10sec rather than 10nm warning.

[Pontius Navigator]

Used to be able to hear them very loud for minutes before they came over at night

Yes but could you FEEL them before you heard them?

[Gainesy]

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

[Agaricus bisporus]

10nm warning.

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!

[nice castle]

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.

[The Helpful Stacker]

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.:}

[Gainesy]

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.

[coley chaos]

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

[NutLoose]

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

[Mechta]

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

Have you actually seen them? Do you know they are Chinooks? Merlins are just as loud but with about 10sec rather than 10nm warning.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!

[whowhenwhy]

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

[LBP PC DC]

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