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Many thanks to Peter Lovegrove for his excellent article in the latest gyro news.Prior to flying my Butterfly after the Cooma event, I decided to ensure my rotor head system was set-up exactly right. I read the article several times and proceeded to action. I believe it is important to note here, that not all hub blocks are the same. For instance my old original 1978 Benson Blades and Hub Bar have what appeared to me to be circular machined rebates into each side of the hub block. Upon discussing same with a number of people I was assured that each side of the block had been warn in by previous teeter bushes (tophats). This seems logical as they are not the same depth.When I was advised to set my head up on Butterfly initially, the deal was to ensure a gap of 2.490" between inside faces of tophat teeter bushes. The distance between inside faces of towers 2.5".To ensure this gap we were to make up shims of 6061-T6 from .0025" material and to place them each side of the towers between the teeter bushes and the thrust washers. They would require machining down to give the correct gap and tolerances. This may well have been the go on a hub block with no side rebates.I have made up shims of same material one at 9 thou and the other at 14 thou that go between the inside faces of teeter towers and against the face of the hub block on both sides. Due to the different thickness, each face of the block and each shimm is marked, for correct placement. I now have about three thou float and the teeter bolt and block teeter on the bushes as required.After flying for a couple of hours with two mates yesterday, I was very pleased at how smooth the whole system was. I had a look at the rotor head set-up on another gyro. We found it had no float at all. He advised me he has a slight two per rev through the stick. We reviewed the article and discussed the fact that he would need to shim inside faces also.I would appreciate any further comment on this, it is so easy to get it wrong and I believe not fully understood or appreciated. The rebates in the hub block certainly caught me out. If it's not set-up correctly you can find the block sliding on the teeter bolt, causing excessive wear to bolt and block, ect. Cheers,Mitch.www.thebutterflyllc.com
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Mitch, zero to three thou side float is fine, with the teeter bolt correctly tensioned. Zero clearance can only correctly be achieved by starting with a shimmed clearance, gauge the clearance, and then remove only the correct thickness of shim to eliminate that clearance. It is far easier just to run a small clearance.Tim McClure
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Do I take it then Tim that no float at all is OK, cause Geofs has no perceptible float at all, neither of us could feel it, nor see it. The teeter bolt is teetering through the teeter bushes but seems to grip and stop then continue to rotate in unison with the bar. I was thinking maybe the boltis pinched up too tight and it's pulling his towers in a tad, didn't notice any witness marks on towers or block though. Am I right to think that we need to shim the inside of the bush face to the block, in order that we get the float occurring at the teeter bushes?And is no float at all OK?Thanks Tim.Mitch.www.thebutterflyllc.com
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Thanks Chuck,Good history and explaination of different set-ups.Butterfly has alum top hats, teflon thrust washer under brim of hat, then the machined 6061T-6 .0025" shim washer of desired thicknes. Top hat goes through a bronze phosphur oil impregnated bush. Due to my recessed holes in block I had to shim the inside face of top hats to hub block, with 6061-T6, so it's all the same material.Appreciate your help.Mitch.www.thebutterflyllc.com
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I have been using needle roller bearings in the towers and to control the end float for over 500 hrs now and they still look newGot the idea from owen dull years ago and have never had a problem...also run 0 clearance for end float..adjustable with a shim washer.Only percievable prob is getting dirt in them when transporting and as i tow with rotors on it hasnt been an issue.
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Hey Mark,That's pretty much what I'd been told by Paul, with respect to the O float and dirt grit.Thanks,Mitch.www.thebutterflyllc.com
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I received a suprise in the mail today, Peter Lovegrove has just brought out Volume 6 of 'Gyroplane Miscellavia', your Editor derived the article on setting up rotors from one of these volumes.Your Librarian has the 5 volume set available for loan. Fascinating stuff!John EvansThink logically and do things well, think laterally and do things better.
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Mark, what sort of setup do you use to transport with rotors on? Obviously you have supports under the blades , but how much of the blade weight needs to carried? Sure would make transporting a bit easier.
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No Mitch, Richard Douglas is now the Librarian, he's in the directry on page 4 of Gyro News.Peter Lovegrove has done an incredible job collecting a comprehensive array of articles from all over. It is all done from a British point of view, he is deeply envious of our freedoms, and frustrated by bureucratic obstruction. Much of the material was actually written by Peter and published in the British Rotorcraft Associaion magazine while he was its Editor. Some of the material was taken from Gyro News.John EvansThink logically and do things well, think laterally and do things better.
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Eric....this is how ive carried it half way round oz with no probs other than a high c of g.
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