No Wop Wop From A 205?

[Mark_]

There is presently a 205 in Banff, making daily flights. I see the machine every day but have yet to hear the classic Bell medium blade slap. What's up with that? At this altitude and temp I would assume the driver is pulling plenty of pitch. Maybe he's flying very light or maybe it's the angle / distance from the machine? The loudest sound from this machine is the TR. Any thoughts boys?

 

Mark

[Elvis]

Angle...most of the blade noise is projected foward, ever notice when a "Huey" passes over head the noise lowers.

[ChopperBob]

Thats why you can hear a huey coming from 5 million miles out, but when it passes, you only hear the tail rotor.

[cap]

Power setting. Any 205 check-out or course of good quality will have "Noise Abatement Settings and Procedures" as part of the Check-out. After many years of flying one, you can tell the A/S that the 205 is travelling and whether it's a 205 or a 212 because the blade sounds are different. If the 205 has "the pedal to the metal" then the blades will really "crack", but it gives away your power settings to the educated ear. With the advent of the new 205 conversions with the 212 M/R blades one has to be careful what they say in that regard lest they be wrong as it gets closer or passes.

[Mark_]

Thanks guys...angle from A/C and power setting...makes perfect sense.

Mark

[Bell Hell]

Seems like the 212 rotor really cracks when going downhill, otherwise it's pretty much the same in most phases of flight. It is different than a straight 205 rotor, whatever causes it.

[Elvis]

Blade profile, the thinner blade on the 212 is a little quieter

[Longdog]

Kudo's to the pilots involved for flying neighborly and realizing the nature and sensitivity of the people and wildlife in the area. This is the kind of professionalism that should be demonstrated while flying in a high profile area, to help with the acceptance of rotary wing operations. Good on you guys.

[cap]

Also to be remembered is the fact the some manufacturers changed the M/R blades from blunt 90 degree corners at the tip to a 45 degree angle cut-back from the leading edge to the trailing edge of the blade tips. This helped reduce the low pressure area created by the older blade tips and therfore took some of that 'crack' away that sometimes caused problems. You're going to get some M/R blade noise no matter what you do, but with the new blade technology, proper training and descent profiles, much of or all of that 'crack' can be dissipated.

[Skids Up]

...much of or all of that 'crack' can be dissipated.

 

Yeah, but Cap, what fun is that??? :lol:

 

"Can you hear me now?" :prop: