Originally Posted by
AnFI
johnny
what are you trying to get at with this?
are you thinking that compressive elastomerics are better?
these (old fashioned) hinged heads are generally exceptionally smooth (when set up properly) and fly beautifully
the downside issue being bearing wear and lubrication (maintenance), otherwise pretty good eh?
or what is your thinking?
What I'm trying to do here is to gain knowledge.
For example, I know that a BO 105/BK 117 rotor head has four steel wire TT-straps with 12,000 windings of 0.25mm˛ steel wire each, which take the blades' centrifugal loads and allow smooth blade pitch change.
I've also seen a picture of an early version of that very head with laminated shim packs, similar to what the Hughes 500 series uses.
I know Bell also uses steel wire TT-straps on many helicopters, as well as elastomeric solutions on some. For most Western helicopters, a quick Google search brings up all kinds of material that answers the question of how things work, Robinson actually makes all their materials publically available I think.
I was just curious what is done in terms of blade retention in Eastern countries, as you obviously can't just look at a picture of the helicopter and see what's inside the main rotor hub. As many of the Mil helicopters were developed during the cold war, I suppose they might have gone a different way than the Western world, but that's just speculation.
It comes down to pure curiosity. I opened this thread because Google wouldn't bring up anything answering my question really, and I figured this would be read by people who might have worked with or on those helicopters.