Fairey Rotodyne 2.0 - Finished pics page 14

[rickshaw]

I've started work on the rotors.  I'm in two minds over whether to use the standard tip jets or replace them with something bigger. 

The ""rotodyne"" project I was going to start will be much bigger. Planning on using either a Transall or C-130 fuselage. For the rotor tips, I was thinking of doing something like a BERP shaped tip, but then have three or four very small jets sandwiched in between the top an bottom of the shape. Something like that proposed hypersonic aircraft's wing that the Brits came up with.

Back in the early 1960s, that was what Fairey came up with basically.  It was a set of outlets along the rear edge if each blade tip.  Apparently it reduced the amount of noise considerably from the 60-80 decibels it normally emitted.   I modeled it on my RAN Rotodyne's blades:

[zenrat]

I'm aware of the low(er) noise tip design.
Unfortunately it proved impractical when used in conjunction with a Pegasus and was ditched in favour of soundproofing the cabin and moving the heliports further from the more expensive houses.

[NARSES2]

and moving the heliports further from the more expensive houses.

I'm surprised they didn't actually do that 

I suppose Battersea Heliport was stuck between the posh bit - Chelsea - and the working class, at the time anyway, bit - Battersea - so it wouldn't have taken much moving.

[rickshaw]

and moving the heliports further from the more expensive houses.

I'm surprised they didn't actually do that 

I suppose Battersea Heliport was stuck between the posh bit - Chelsea - and the working class, at the time anyway, bit - Battersea - so it wouldn't have taken much moving.

What has always surprised me is the complaint about the noise that the Rotodyne supposedly made and how loud it was.  Yet, today, we have the V-22 in Operation and it is noisier than the Rotodyne was...   

[PR19_Kit]

I think the 'dyne's noise, the sound that REALLY got to people, was a higher frequency than the V-22's sound. When the tip jets started up there was a high pitched whistle until the igniters lit, and they added a much louder roar to the whistle. All this on top of the twin Elands of course, but they sounded just like a couple of Darts, half a Viscount. When they did the approach test flights at Benson I could hear the tip jets start up before I could hear the Elands, and I could see them anyway as it made a sort of spiral smoke trail as it approached.

The V-22 sounds like a big turbo-prop with added helicopter Whup-Whup on top of it, and doesn't have the same high frequency input that the 'dyne had.

Having said that, Fairey made a lot of progress in quieting the 'dyne down later on apparently, but that was well after it left Benson so I never heard the 'quiet' version.

[kitnut617]

Interestingly I didn't find the V-22 that did the flying display at USMC Yuma airshow to be very noisy at all. Not compared to the Cobras that also did their flying display. I wasn't standing very far from the V-22 either.

[Caveman]

I may be misremembering but noise dBs go up with the cube of the exhaust velocity. Something to do with shear planes mixing different velocity air flows. High pitch sounds tend to be more annoying but attenuate in the atmosphere faster.

So helicopters have relatively noisy turbines which you can hear up close but at distance it's blade noise which dominates. Added to the fact that the engine exhaust is inside the rotor wash.

Rotordyne with its tip jets had very small exhaust areas and so required high speed exhausts to produce sufficient force. Small area made them high pitch too. So loud and annoying.

I think the modern winner of worst noise is F35 when hovering though.

[PR19_Kit]

I think the modern winner of worst noise is F35 when hovering though.

I'd agree with that too, possibly competing with a Typhoon doing a QRA take-off requiring full burner.

[kerick]

Saw and heard a Harrier at an airshow once hovering in front of the crowd. Now that was loud!!!
Plus IIRC the worst helicopter noise comes from the tail rotor as its higher RPM.

[Captain Canada]

For sure Robert, the Osprey is barely audible from what I remember of a Huey or a Cobra ! Mind you, those two were both the new Z's and barely audible at all. The Osprey did make some nice sounds at a few angles. Kind of like the USCG Dolphins we see all the time back home. They make some awesome sounds as they are turning !

[NARSES2]

I never heard the Rotodyne, or if I did I don't remember, but people I know who lived near Battersea Heliport at the time said it was the particular "whine" that got to you

[zenrat]

Started sanding off the zimmerit.  It's not going to look pretty but it is going to be smooth again and then I can repaint.

[zenrat]

Sand, sand, sand...

Nearly there.

[zenrat]

Sanding is almost completed.  I realised that as I wasn't scratchbuilding an interior I needed to glue the passenger access door into place.  There will be a smidge more sanding needed around that and then I can paint again.
It won't be done by May 31st but as I am on leave again for the first two weeks of June I am hopeful I can get it done before the extended GB deadline.

[zenrat]

Primer...

...again.