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Posting these photos mainly for you Aussies who may not have seen much of this stuff!! We got plenty of it ere since the big rains.
But we call um wildflowers, and they come in mobs of
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It would reduce the trimm tension considerably.It would also make the stabelising effect of the offset [ floated stick] less effective, but not nuf to wurry bout.
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Im no rocket scientest Browny, i just take note. [ but sumtimes i have trouble readn me own riten.]
By efficiancy i mean the amount of power required to sustain xx AS and alt.An efficiant blade obviously will need less power to hold xx AS than an inefficiant set, all other things be"n equal.And governing the power required is drag wen it comes to rotors. If your holdn alt, they are both supplyn the same lift.And different profile/cruise rpm/lift blades have different props n cons.The most efficiant blade is longer [ lower loadn] with minimal cone.But longer blades are slower in cyclic responce, so you got to trade for your use.Generaly speakn, the greater the drag, the greater the trimm tension needed, and a smaller offset means the trimm tension dont need to be as high.All this goes against everythn a bloke has told me. This bloke [ Chuck Beaty] is my gyro god, there aint much he dont know. But he cant explain why my supposed primitive dragy profile blades need less power to do the same job as the more efficiant 8H12 profile. ???And Tony, id probably go to Birdsvill, it it wasnt so wet ere.
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Seems like this small difference in offset can make a huge change in the way a gyro reacts to inputs. Erring on the side of caution I`ll reduce the offset to 7/8 of an inch, then fly it, and see how it feels. My gyro had a set of Goodwin 25 footers and needed a fair ammount of spring tension. I now have a set of Patroney 26 footers and it needs lots less tension. So...can I assume that the Goodwins have greater drag...The other thing I noticed is how much heavier those Patroneys are.. I just about blew a pupu valve liftin them up on the tower ;D ;DFWIW I did quite a bit of experimenting with various torque tube offsets around 2003. I had a set of GG 30" blades that were more efficient than the RAF 30" BUT I had to reduce the 1" RAF offset. I was trying to find a set of Oz blades that would work with the RAF rotor head. At that time there was quite a market in the US for smoother 30" blades with the $ value at that time. Unfortunately people were not interested when they had to change the torque tube. Not long after that Raf sacked me as their agent due to my stability issues with their product. That when I decided to develop our Firebird.1" to 7/8" is a 12.5% change, a reasonable change in aviation. I went from 5/8" to 9/16" (10%) during one experiment.Also I found that by changing RAF blade pitch, thus altering rotor rpm, the tension of the trim springs changed quite a bit.Aussie Paul.
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G"Day Browny, I asume you are in "Aaterorora" I"ve been playing with alternators for 45 yrs. and we always had the policy of "the faster the better" The rotors are well balanced and if you don"t require electrical energy from the Alt the rotor simply becomes a flywheel. Some fords 1970 era had a big pulley on the V8s and a smaller pulley on the 6 cyls. I always assumed that was only the prevent belt slip with sudden acceleration. My advise is go for the small pulley. -- Love to come and fly through those southern alps. with you one day!
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Thanks for that guys. This computer stuff is a bit daunting with all the new gear out there now. There is a couple of specialised EFI tuning places not too far from here and they both reckon those Links are a good bit of gear, which they would want to be for the price!! Do you guys with EFI setups run two fuel pumps or just one?
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on my first set up I was advised to put [2 fuel pumps into 1] system and also advised to make up a simple check valve block, so if either pump failed the good pump wouldn"t simply pump fuel back through the failed pump. the check valve block always worked when tested but thankfully I never needed it through any pump failure. this doesn"t require any flicking a switch , so that has it"s bonuses.
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G"Day Mark. I machined down a subaru flywheel to lighten it for my rotax reduction on my EA81 and also for my Neal H. box on my EJ25. On both occasions I machined off all timing marks. After installation I set the engine at no. 1 TDC and put a dot punch somewhere covenant on the flywheel indicating TDC plus a few more dots at 5deg. intervals. Sounds like you could do with a pod and heater down there. Been raining here for 4 weeks. Got caught in one rain storm while flying. Stings a bit and motor started spluttering in protest but came right during landing.
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Heh Browny, Are you using the std EA81 bell housing, if so then the timing marks are viewed through a cut out on the right side , on the front of the bell housing. The timing marks are stamped on the flywheel. If you don"t have any of these, I"ll take some photos and send to you. Darrell
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Sounds like the suits a great idea if you go down in those Alps Browny. I"ve heard of some people surviving up there by sleeping inside a dead cow. As far as marking 5deg. on the fly-wheel I went to my craft to check the distance but can"t rotate the prop as it"s jammed in amongst 3 other gyro"s. As I am useless with maths and can"t work it out from diameter because I wagged maths classes at high school (Thats why I became a Gyro-naut instead of an Astra-naut) I adjusted the dividers until they walked around the fly-wheel 36 times and then halved the marks. Suppose you could use a protractor on the pulley. Good luck
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ok I was being lazy there for not helping, I only thought of my gyro at the glider strip. but
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Nose heavy blades are the same asa HS ona HTL machine, a bandaid.Theres no real reason to make them nose heavy.They make for heavy cyclic pressures, slow rotor responce so on a stable machine they make it less controlable. Ona unstable machine they dont stabilise, just hide the instability, to a point.Either machine can more easily run into its rotor if the rotor is too slow cyclicy.So yes, it should be considered to stay away from nose heavy blades.
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And Hi T-Bird,The Magni blades are the only "overbalanced" (ie, lower than 25%) that I know of at the moment. I have been waiting for a long time to get my hands on a beat up set of Dragon Wings that I can cut into cross-sections and then weigh and measure ..... any volunteers?
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Hi Mark thanks for your informative reply. Jukka also designed the rotorhead and hubbar for the Magni in 1974 with no structural failures to date. Some of these hubbars have done over 5000 hours in commercial operations.I assume from your reply that Magni is the only heavy nose gyro rotor.
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Hi T-Bird,The Magni blades are the only ones that I currently know of that come in at a true average 25% chord and which in the tip region are even a little "over-balanced", which is all good because they are only slightly "over balanced".Every other gyro blade that I"ve managed to get pieces of and weighed, measured and balanced is usually in the 30% region. From an aerodynamicist"s perspective, this would be unsatisfactory because the 8H12 should be balanced at 25%. Over the decades I"ve built up a nice collection of helicopter and gyro blade cross sections, and by studying those one can see that unless great care is taken to make the rear 60% of a blade as light as possible, it becomes very, very hard to maintain a quarter chord (25%) balance. This task is particularly hard with aluminium extruded blades, because the rear areas of extrusions with thin skin thicknesses towards the rear usually don"t extrude as well as the forward thicker sections, leading to an unacceptably high scrapping rate, as well as subtle wrinkling or "oil canning" and susceptibility to damage for the one"s that aren"t scrapped.Of course the solution is to have the extrusion come out with thicker rear skins balancing at something like a 33 to 35% balance, then to weight the nose to get the 25% balance. Where Magni uses lead, and Bell and Hughes used brass, our own Richard Myrtle at Yarrawonga (Vic) is experimenting with stainless steel rod in extrusions he got produced in China about 5 years ago. I am confident that Richard is "on the right track" and I commend him for his persistence and ingenuity.Aluminium extrusions work well in gyros because gyro blades are relatively short in span and extrusions are comparatively stiff, so there won"t be any significant risk of them twisting nose up at the relative airspeeds that our blades operate at. And, because our blades are rigidly bolted at a fixed pitch to a hub of some kind, we don"t have to worry about pitch-link overloads that helicopter designers fret over. In other words, in gyros with fixed pitch, if Blade A is wanting to twist nose-up, Blade B will probably be wanting to counteract that and those stresses and strains are carried through the hub without the pilot ever being aware of the torture that is occurring within the hub bar. It"s all very neat, really. Another area where the astonishing simplicity of gyros masks the underlying dynamic complexities of these rotating systems.Of course the real beauty of the Magni composite blade is that the internal spar tapers along its entire length, whereas extruded blades have a constant unvarying cross-section. This means that the outer 2/3rd of extruded blades are stiffer, stronger and heavier than they need to be. Being heavier than they need to be might not necessarily be a disadvantage because they"ll "hang on" longer during a flare.So far as your comment about the Magni sideplate style rotor head is concerned, yes, I agree. I"ve always been impressed by the sideplate style hub because its very simple and lots of project helicopters have been built similarly over the decades - and, there"s no hub bar in any conventional sense. So far as gyroplanes are concerned, I note that the big South African Wagtail gyro has a Magni-style-hub-on-steroids look to it.Cheers,Mark Regan
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