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quote:Originally posted by NiqueNaqueChuck,No doubt you've seen delta heads, how do they compare or work in comparison to a conventional head in say a three bladed rotor?Cheers,Nick.
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In view of the spate of failures the following info may be of interest.6061 T6 Ultimate tensile strength 310 mpa Yield 276 " Elongation 12%2024 T3 UTS 483 " Y 345 " E 18%4130N UTS 670 " Y 435 " E 25%4140 UTS 1020 "[spring steel]Y 675 " E 18%Density Aluminium 2.78 gm/cc Steel 7.85 "John EvansThink logically and do things well, think laterally and do things better.
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John, back in the early 80s the US hub bars seemed to be 2024-T3. If I remember correctly, I believe Gerry Goodwin used 2024-T3 back then. Anyone else remember?Aussie Paul. [
]www.firebirdgyros.com
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Paul,Back in the 80's - what was a gyro plane?? I saw little nellie, but I thought that was a helicopter..Cheers,Nick.
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Obviously fatigue resistance is more important than outright strength, hence some of the very important points Nick made some time ago on this and other threads regarding the effects of stress raisers such as holes and machining marks.Having said that, it raises the issue of hole locations near the edge, e.g. diagonal teeter block bolt holes. We are now seeing failures through these. I gather that the problem that emerged with 2024 involved corrosion stress raisers.It seems that the requirement for a safety factor of 10 for the rotor stems from the need to allow for the effects of these breaches in the integrity of the hub bar.The other side of the fatigue resistance question obviously involves the fatigue characteristics of the metal in use. My impression at the moment is that intelligent use of spring steel would allow the design of hub bars that flex to give the appropriate coning angle rather than use a rigid bar with the coning angle bent into it, or worse still, a straight bar with the coning angle provided by wedges at the ends, whereby inappropriate forces are applied to the hub bar.Neither 2024 or 6061 would seem to have fatigue characteristics as good as spring steel.John EvansThink logically and do things well, think laterally and do things better.
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