HUB BARS ON GYRO'S FOOD FOR THOUGHT ONLY

[asra]

ive seen a long set of cheek plates, reinforced by tube or box half way along recently on another forum. this was to raise the rotor head without a new mast.could this be more or less able to flex???mabee a long set of cheek plates folowed by another small section of mast might create flexability in an otherwise rigid design???this would relive shake from the mast before it is attached to the mass of the rest of the machine ie.. engine and its thrust.could the thrust created pin the mast and amplify rigidity???should the mast be measured from the engines attachment to the mast when figuring out how much length there is to flex??could the engine be totaly mounted on the keel to give more freedom of resonence obsorbtion to the mast???the suport for the thrust could bypass [go around] the mast and be triangulated through the seat support to the front of the gyro.would require large plates attaching the mast to the keel though and there fore chasing tail for flexability[B)]how do tractor gyro's fair transfering thrust from the keel to the mast?my head is starting to hurt! i know, i know a head like this should hurt, hoodyps.. is the attachment at the top of my tall tail under high airflow mabee creating rigidness at the top of the mast???or mabee transfering one shake into another???

[asra]

Mark, can you check your e-mail address please? mrford61@yahoo.com.auBarry Ferguson,ASRA WebmasterPh (07)5464-4993Int +61 7 5464-4993

[mrford61]

Barry,When I tried to get into it a message comes up saying there is a temporary problem with access.Maybe it is because I hardly ever use it. To be honest I only opened the account to join a couple of forums. I will keep trying. Mark.

[asra]

Magni gyroplanes use a very different type of hub bar.Rather than being made of solid 1 inch flat, they use 2 x vertical flats with seperators, or spacers between them.The rotor head fitts between both, and Jesus bolt, sandwitches the lot.Could this be the answer to our hub bar problem ??????????? Tried to down load pic but failed, seems system has changed.Regards Sam. []

[mrford61]

Barry,Email is working again now. Mark.

[NiqueNaque]

Sam,Not necessarily, subject to design considerations you could just be moving the bottle neck as with lane changes in traffic.We may see blade root failures in the Magni in lieu of hub bar failures.. time will tell.As has been stressed before, check, check and check again. Any hub bar with some hours up is worthy of inspection, even a new one - I forget who had the Larkin bar with barely more than 100hrs, was it far Ken the gyro pilot? I would advocate that any hub bar beyond 250 hrs is worthy of a strip down and crack test, maybe an X ray at 500 would be a good idea as well for two seaters.. just to see how they are going.A good idea might be to stress test them, ie, when they are made they should be put in a jig and a load applied to the bar, the deflection and load should then be measured in 1G increments and recorded in the gyro's registration data base. With every registration or every 100 hours the same measurement should be taken to check for any variances in the deflection for the same load or if there has been any change of shape in the loaded or unloaded condition, this at the least should be an indicator, and if the bar is loaded up to, say, 5G (we should have this safety factor in such components) and visualy inspected for cracks with a penetrant dye (degreaser and water = bush mechanics dye test). This at least might help to detect problems.Cheers,Nick.

[asra]

have a very corroded 2ft 3/4 larkin hub bar available for destructive testing if it helps, wont use it ever, sept for the blocks mabee.have half of a 4ft 3/4 hub bar too, used a piece for reinforcing the nose wheel.hoody

[NiqueNaque]

Hoodman,Generous of you to offer..Cheers,nick.

[asra]

Magni Hub barImage Insert: 55.73

[Greg Mitchell]

This off the SSC. Similar to Magni but run on a std Benson type head. And the blades fold.Mitch.Image Insert: 55.65

[Greg Mitchell]

Gents,This shows how this system attaches to a std head.Image Insert: 55.46

[asra]

Ideally, there should be virtually no need for stiffness in the mast, except when taxiing.In a properly balanced system the roto pulls one way (varying according to control action)and the body pulls in the other direction, with the mast "stretched" between them.In theory (definitely not in practice - there would be numerous problems)), the mast could be replaced with a steel cable holding rotors to body.Mast stiffness is of minimal benefit. The longitudinal strength of the mast is more importantthan stiffness. Most masts are probably over-engineered to buggery(oops) in that sense.Their longitudinal strength is probably limited by all the holespeople drill in them for mounting points.Also, the square or rectangular profiles must do strange things to circular vibrational forces.I think I'd feel safer under a light tubular mast with a steel cable running up the centre for safety, mounted at the right place for minimal torsional forces.Don

[asra]

I'm a little concerned that this discussion is focussed on beefing things up to cope with the vibration, rather than eliminating the vibration.That will only delay the failure.

[Greg Mitchell]

Don, The system above is designed to be flown on two place Super Sky Car and has jump take off capability all running on std rotor head configuration. Soon, testing will determine its suitability.Cheers,Mitch.www.thebutterflyllc.com

[Brian]

One of the biggest problems I see is that in other parts of the world gyros are not flown anywhere near as much as they are in Australia and to compound the problem, we have been bought up with gyros actually being used like aerial motorbikes and that in itself has caused a new problem, with the availabilty of the Suby EA 81 and now with the Suby 2.2 and 2.5 being used to power gyros and of course, we have bigge fuel tanks, pods or canopys, plenty of instruments, radios [even a CD or Mp3 player and of course, a toolbox with associated spanners and fencing pliers we of course stick some bigger blades to lift all the mass described !!! 27 ft'ers are a bit small so hang a set of 28's Patroneys on and a way we go and do manourvers all day long and everyday we work that scare rotor builders to their socks!! Heavy weight gyros and high energy manourvers are going to try anything out and I believe that a lot of the options currently being presented are going to be found wanting in some way shape or form. I hope I'm wrong but most of the options being presented including Sportcopter blades [which I think are just great] DONT have any hours up on them of any consequence to prove their reliability.Till we see designs with 2000 plus hours on them, we have very little idea how great they are going to be!!! Its interesting that a set of Ricks 27's that have over 2000 hours of scrub cutting work behind them show no signs of hub bar cracking despite being used on the gyro mentioned above plus being used on strips so rough that a cow wouldnt walk on ! Its also interesting that Rick DIDNT bend the hub bar but used blocks at the ends to get the correct pitch etc. I personally dont like the idea of bending that hub bar !! Can anyone tell me why bending a 25 mm Aluminium hub bar WONT weaken it cause a bit of wire is strong till you bend it but then you hook a set of strainers on it and its going to break just where you bent it ??Brian