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Attachment points - Safety


darkwing
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Hi

I would like to read from people that have moved from high attachment point motors to low attachment points or low attachment points to high.

Have you found the sensation unnerving/unsafe?

Has the trade off between stability and maneouverability been worth the switch (high to low or low to high)?

Would low hang points (PAP/H&E/PXP style) be more unsafe than high hang points, in the event of shackle pin failure, in spite of the back up strap on the harness? There seem to have been a few fatalities where this could have been the cause...

I have only ever flown high attachment point machines hence the reason for the questions. I would love to try low attachment points but there is no one in my area who has such a machine. I am looking at either getting a Simonini powered machine (Fly Gold 115) with high attachment points or a PAP ROS 125 and at my weight (83kg), these motors should be fine. I like the idea of a clutch, the stainless frame and forced cooling but the attachment points on the PAP worry me a bit.

Any comments?

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Unless you are at cloud base with your engine off.

Or anywhere else (like thermalling) with your engine off for that matter... Crap with high hangies, and yes... I have tried it lots.

My 'personal' pref is for the low hang points, I just like the way it feels, and the ability to weight shift (something like a tiny bit closer to the way it feels on a Paraglider.)

SW :D

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Unless you are at cloud base with your engine off.

Or anywhere else (like thermalling) with your engine off for that matter... Crap with high hangies, and yes... I have tried it lots.

and (honestly) the ratio of time you spend in flight engine off to engine on is...? Is the OP planning to spend lots of time engine off to get these 'benefits'?

A friend and I have been conducting tests with a hang test frame with load measurement in the strops. We experimented with a Bailey (fixed mid hang points) and a Parajet (low active arms) and using the same pilot achieved identical figures for loading and unloading in each direction through weightshift. So the question is... active arms allow the unit to swivel but are they actually giving improved weightshift or is it partly psychosomatic that the weightshift is better than it really is? Paul Bailey recently said in conversation that he was adding active arms because that was the fashion these days and not because they actually improved a machine. It has become what many expect but do they really understand why?

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Thanks for all the response. It appears that it is more a preference than anything else - am I correct in assuming so?

No-one has mentioned anything about the safety aspect though. Would you believe one system to be safer than the other? i.e shackle pin breaks during a spiral dive - would it not make the situation worse? Or during turbulence, would one offer more safety/input for correction over the other?

If I don't post again, have a great Christmas!!!

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Well as far as safety goes, this might be controversial but I guess the fixed bars like on the flatop would be safest. There have been reports of problems with the moving arm types and also the over the shoulder high hang points. They all have secondary safety attachment systems to the harness etc, but even this might cause a spiral if set up badly.

That’s just my opinion, maybe some of the higher flight time guys have some more imput?

Cheers

Mikey

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  • 2 weeks later...
Darkwing, what's a shackle pin and how might it fail?

Dave

A shackle is a U shaped piece of metal with a pin that slots through the open end. The pin is threaded at one end. The shackles that concern us are used to secure the carabineers, and hence the wing, to the swinging arm on the motor.

Any failure of the shackle pin will result in you having a bad day.

There are a number of failure modes for the pin but the most likely are:-

1. Vibrating loose.

2. Metal fatigue

3. Excessive wear.

These failure modes can easily be mitigated by ensuring you use a secondary locking mechanism (key ring, locking wire or tie wrap), carry out regular checks on the pins to ensure no wear and only use manufacturer approved parts if you need to replace one. My policy is to replace shackles & carabineers no later than 50 flight hours to keep the risk ALARP.

Alan

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This is the swing arm on my H&E. The single marine type shackle and 4mm pin that was standard has been removed and replaced with heavier shackles. Also the pins have been removed from the shackle and the threaded end of the shackle drilled out so I now have 6mm stainless nut and bolts which I can replace routinely. If the swing arm is hollow it can cut into the bolt.

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I've flown both floating set ups and fixed hangpoints. I think the floating arms may help to combat some of the torque steer but there wasn't an issue so much with that on the PAP, H&E or the Parajet that I flew as they were rellatively low powered machines. I chose the Walkerjet firstly, before I upgraded to the Flat-Top, because of the strength of the forward pointing, fixed hangpoint bars. They could definately stop the weight of the motor from mashing you into the ground, in the event of a tumble. Something I've seen more than once and not nice. Secondly, the height of the hangpoints is not too low, so it feels very stable, but not too high either, so you can still get some weightshift. And last of all, the fixed bars make sure you are sat in a strong seat, 16 inches off the ground. Nice for strapping in, pre flight, or if you are too chicken to land on your feet, or stall the wing a few feet up, too high a drop to land using only your legs. You dont have to land on your coxix and risk spinal damage.

Someone said, "whatever you fly, you'll prefer"...... My instructor was a bit put out that I didn't go for the make he was offering. My advice.....do your own research, which, ofcourse, was how this thread started. The answers you get, however, aren't allways the ones you'll want to hear. In short, I'd say fly the safest unit you can buy, initially, then when more experienced, if the safest one doesn't satisfy all of your requirements, change for one that does.

Dave

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