Dave24 Posted December 22, 2009 Share Posted December 22, 2009 Can anyone explain the safety issue thing with low or high attachment points? I wasn't aware of safety problems and as a newbie would like to avoid getting caught up in any problems. I tried to follow the recent link discussing it, but came away feeling lost since there wasn't a basic explanation of what the problems are. Thx Quote Link to comment Share on other sites More sharing options...
fanman Posted December 23, 2009 Share Posted December 23, 2009 Ok I know this doesn't fully answer your question but hang points aren't just high or low, they can also be at a multitude of points in between. Possibly the best answer for your question is here... http://footflyer.com/Equipment/Suspensi ... ystems.htm Quote Link to comment Share on other sites More sharing options...
alan_k Posted December 23, 2009 Share Posted December 23, 2009 Check out 'Harness Myths' accessible from the same page, or direct http://footflyer.com/Equipment/Suspensi ... /index.htm Alan Quote Link to comment Share on other sites More sharing options...
Dave24 Posted December 30, 2009 Author Share Posted December 30, 2009 Thanks for the link. I've read the articles but don't see any safety issues. I see the point that low hang points cause you to "wobble" under power more, but gives you a better ability to weight-shift. The opposite is true for high hang-points. I also see the comment that you get used to either way and notice that many people/motors use low and many use high hang-points. Is there something I'm missing, because I've heard about the "dangers" of low hang points, but don't actually see what the safety issue is. Thanks for any advice on this. Dave Quote Link to comment Share on other sites More sharing options...
norman Posted December 30, 2009 Share Posted December 30, 2009 'Dangers' might be too strong a word, more potential design vulnerabilities? If an arm breaks under load then you could be faced with an uncontrollable spiral due to the asymmetric loading. I believe this effect has been cited in one accident report. I know one very experienced instructor/constructor who prefers the high hang-point configuration for its inherent safety in this respect. Perhaps others more experienced could comment on the theme? Quote Link to comment Share on other sites More sharing options...
fanman Posted January 2, 2010 Share Posted January 2, 2010 The arms themselves tend not to be the failure point, it's usually the fittings, ie pivot bolts or shackles. Quote Link to comment Share on other sites More sharing options...
norman Posted January 2, 2010 Share Posted January 2, 2010 Fanman, Thanks for highlighting that important distinction. Lazy writing - yes, as i understand it, It is indeed component failure that mostly raises concerns, not necessarily the actual arm itself which tend to be easier to engineer strength and reliability into. To be more correct then; I point toward the whole assembly and the general design philosophy (swing arms in general) and their potential vulnerability. A graphic illustration of your point just received by email. The letter below discusses the question being raised here rather well. The letter, provided by the gentleman I referred to a short while ago, makes very interesting reading, particularly given the credentials of the author and his approach to the problem studied. Investigation into the failure of a swinging arm mounting bolt on a Clemente Snap 145 Paramotor. The lesson for me here is of the vital importance of a thorough pre-flight inspection.. every time. Should we might consider 'self-lifeing' the critical components that are under repeated, regular strain? Replacing these components (correctly with manufacturer approved items) after a suitable interval (flying hours) or when they show any sign of wear might contribute to our safety by preempting a failure. Sounds like one for our Engineering Members. Alan and Pete B might have some input for us. As ever - all comments and views welcome. Quote Link to comment Share on other sites More sharing options...
garyfreefly Posted January 2, 2010 Share Posted January 2, 2010 sounds like the man knows his stuff........ where can I get some high tensile replacement bolts for my Pap.....then as I am not going to have a fixed or high hang point again because I have been there ....before And I dont like them...... Quote Link to comment Share on other sites More sharing options...
pete_b Posted January 2, 2010 Share Posted January 2, 2010 sounds like the man knows his stuff........ as I am not going to have a fixed or high hang point again because I have been there ....before And I dont like them...... You should be able to get them from any iron mongers possibly DIY store. Parajet are the safest as far as I'm concerned in this area as the pin through the swing arm is supported on both ends. Sorry about the poor picture http://picasaweb.google.co.uk/lh/photo/MCY6x4eTTV5RqjaAH2EZng?authkey=Gv1sRgCJLFseGUvqOqIg&feat=directlink http://lh3.ggpht.com/_sw1nEFvUHPI/SilQWc4Q2iI/AAAAAAAABfc/0voaOtB-v18/IMG00016-20090604-1235.jpg' alt='IMG00016-20090604-1235.jpg'> Quote Link to comment Share on other sites More sharing options...
garyfreefly Posted January 2, 2010 Share Posted January 2, 2010 Yes it is a bad picture is it taken with Simons new singing dancing 12 million pixel camera Quote Link to comment Share on other sites More sharing options...
pete_b Posted January 2, 2010 Share Posted January 2, 2010 No its what was left of my motor Quote Link to comment Share on other sites More sharing options...
tommcb6016 Posted January 2, 2010 Share Posted January 2, 2010 sounds like the man knows his stuff........ as I am not going to have a fixed or high hang point again because I have been there ....before And I dont like them...... You should be able to get them from any iron mongers possibly DIY store. Parajet are the safest as far as I'm concerned in this area as the pin through the swing arm is supported on both ends. Sorry about the poor picture http://picasaweb.google.co.uk/lh/photo/MCY6x4eTTV5RqjaAH2EZng?authkey=Gv1sRgCJLFseGUvqOqIg&feat=directlink http://lh3.ggpht.com/_sw1nEFvUHPI/SilQWc4Q2iI/AAAAAAAABfc/0voaOtB-v18/IMG00016-20090604-1235.jpg' alt='IMG00016-20090604-1235.jpg'> And once the cage is in place it's not possible for the pin to come out. Should I be looking at replacing the pin periodically along with shackels and fittings? I just upgraded to stainless carabiner. Tom Quote Link to comment Share on other sites More sharing options...
pete_b Posted January 3, 2010 Share Posted January 3, 2010 sounds like the man knows his stuff........ as I am not going to have a fixed or high hang point again because I have been there ....before And I dont like them...... You should be able to get them from any iron mongers possibly DIY store. Parajet are the safest as far as I'm concerned in this area as the pin through the swing arm is supported on both ends. Sorry about the poor picture http://picasaweb.google.co.uk/lh/photo/MCY6x4eTTV5RqjaAH2EZng?authkey=Gv1sRgCJLFseGUvqOqIg&feat=directlink http://lh3.ggpht.com/_sw1nEFvUHPI/SilQWc4Q2iI/AAAAAAAABfc/0voaOtB-v18/IMG00016-20090604-1235.jpg' alt='IMG00016-20090604-1235.jpg'> And once the cage is in place it's not possible for the pin to come out. Should I be looking at replacing the pin periodically along with shackels and fittings? I just upgraded to stainless carabiner. Tom What ever you feel comfortable with, If you feel that you are happy taking them out and inspecting them for wear (visable ) then do that if not then replace them every 12 months. depends on how much value you put on your own peace of mind. Quote Link to comment Share on other sites More sharing options...
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