HUB BARS ON GYRO'S FOOD FOR THOUGHT ONLY

[Brian]

Ding, I'm not sure of his surname but he was around back in 94 making rotors and he stopped about 5 years ago. He was from SA and he produced a very good rotor ! He stopped making them as he was having a lot of trouble getting the extusions from USA.Must be somebody out there who knows Ricks surname. Will post some pictures of his hub bar set up tomorrow Ding.Brian

[asra]

Rick Hutchins I think,I flew a set at the Watts Bridge Nationals, very nice and smooth with good lift. I can't recall the alloy, but it was soft compared with 6061 T6, Rick always insisted that the rotor be secured with a strap, as a bungy would distort the trailing edge. There are a few about, that's what is on the Hunter Valley trainer.John EvansThink logically and do things well, think laterally and do things better.

[Brian]

Thanks John !!!Okay, so the hub bar wasnt 6061 T6 . Anyone know what it was made out of ???Brian

[asra]

Oops, I think I've misled you Brian! The hub bar was probably 6061 but the blades were a softer alloy.John EvansThink logically and do things well, think laterally and do things better.

[asra]

Hi Y'all I have been following this thread and I was just wondering, how would a carbon fiber hub bar work? Hummm lighter, stronger, and you could lay it up to any size you wanted. But would it be flexable enough? I dunno. Just something to chew on I reckon.Cheers GuysSonnyIntelligence is not a privilege,it is a gift and should be used for the good of mankind.

[asra]

We have discussed this else where but John is correct, Rick Hutchens manufactured the blades and called them "Ricks Rotors". They were/are of the 8H12 profile and are/were manufactured by Vortech International in the states. Ben Showers Aviation is probably the best person to contact if you want a set.The blades originally called "Fleck" blades are supplied unassembled and you have to make the hub bar as well. There was some controversy over the design of the hub used with RR's, he used wedges at the end of the hub bar to introduce the conning angle of the rotor disk. As for the grade of alloy, I understand all 6061 T6 is imported from the states and the hub bar thickness for the blades was increased to 25mm (1") but in the end, Rick felt there was not the support or feedback in the Gyro movement here and he was concerned about possible litigation issues I believe so he quit.Image Insert: 13.84

[NiqueNaque]

Sonny,Carbon fibre could work but there are alot of issues to consider in its fabrication:Bolt Holes and the method of attachement of the blade roots to the bar.Of principal concern with any bolt hole is flogging out in the hole, considerable bearing area is required to achieve a good connection that will not fail, don't forget that it is a composite, most usually with an epoxy resin binder, and this resin is the weak point. With the right additives in the resin it too can be made as hard as nails, eg glass micro balls make it very hard.You will note that propellor hubs are metal for most carbon fibre blades.Another thing to note is the failure mode, I know aluminium isn't much of one to telegraph its punches, but it can be caught with judicious inspections. Carbon fibre, from what I understand requires only 1% deflection before it goes bang, if you've seen a prop blade failure, you'll know this.If it was designed properly a carbon fibre bar would be excellent as fatigue would not be an issue as carbon fibre has, from memory, no fatigue limit. It would be expensive though with 3k mat costing $60.00 per sq metre at last look 3 years ago, labour to fabricate one would be intensive as well. The resin may have a life when exposed to UV, that also is something to consider. You might as I've said before, make this wonderous hub bar, only to have the roots of the blades fail, one thing chases the other.Cheers,Nick.

[Des Garvin]

Hi Everyone, Thanks to all the people commenting here, you have been very informative with your discussions. Does enyone know if there has been the same cracking observed in the 3/4 inch (19 mm) hub bars or is it more prone to the 1 inch (26 mm) bars on the heavier machines? Des Garvin

[asra]

Bit late for a reply but sports copter has lead lag bushes in & outside hub bar maybe they knew somthing NAH blooby septic tanks! probably stole idea from an Ausie

[Des Garvin]

Well he I am again with more questions on the failures,1. On the hub bars that the cracks were detected did the cracks appear on any particular hole and not the other? (To keep all responces equal "as viewed from the above pillar block view ")2. What is the bolt dia and the distance of the hole edge from the hub bar edge?Thanks Des Garvin

[Brian]

Des, ring Tim McClure.Obviously all the findings are still being collected.Brian