I don't get it.....

[mriya225]

<heli talk>
From everything I understand about the dual main rotor contra-prop configuration--it seems superior to the more traditional tail rotor set to equalize the torque of the transmission on the helicopter's frame... So what gives? Why don't we see it used more frequently? Is it something to do with maintenance, or undisclosed airframe issues?
</heli talk>

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"You did WHAT"?!

[SeeNext]

I've never flown in one but I have spoken to a few guys that have, and apparently the dual rotor configuration causes lots of vibes. Even more than the traditional configuration.

The Chinook (so I'm told) had something like a spring mounted floor to minimise the vibes transmitted to the passengers. Lots of these guys said that you felt very sick after flying in one of these blenders.

I understand there have also been one or two disasters where the synchronisation was lost between the meshing blades and both rotors smashed themselves to pieces.

Not good for public relations.

[mriya225]

That surprises me to hear (but that's not to say it can't be true) because some of those helis operate tight enough that they can virtually fly themselves.

I'm thinking maybe it's probably time to can the guy/gal who balanced the blades on that Chinook you mentioned though.

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"You did WHAT"?!

[Coriolis]

Suspect the answer to yr original question may have something to do with having twice the number of big gearboxes to maintain (plus angle-turners etc, and two major rotor heads instead of one biggie + a tiddler....
Re the BV234 that self-destructed in Shetland, don't think it was anything to do with blade balance, more a gearbox failure, which will not improve your day in any helo...a bit like a main spar failing in your average plank (sorry, stiff-wing), and about as common, thank God

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Ground tested, no fault found

[mriya225]

Awww, c'mon man.....

Where's your sense of adventure?
Jamming and stripping the gearbox and having your heli rattle itself apart around you, mid-air, can't be that bad.
Just bring me close enough to the ground that I'll only get a compound fracture in one of my legs... it's still Miller Time when I regain consciousness baby!

http://www.pprune.org/ubb/NonCGI/tongue.gif You Boys Are Such Whimps! http://www.pprune.org/ubb/NonCGI/tongue.gif

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"You did WHAT"?!

[Coriolis]

OK, I own up to being a wimp...
Ah just LURVE taking gearboxes to bits...
But only AFTER the beast is on the ground...

But then again you girlies always did know a fun thing when you see it ;)

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Ground tested, no fault found