DuPont Teflon Bearing Grease on Crossbar Hinge - Follow-up

A discussion restricted to the topic of hang gliding.
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NMERider
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Post by NMERider »

Dallas Willis wrote:…Again sorry for the derailment.
You actually brought up an important issue by talking about keel lubricant. Many pilots including myself have long believed that crossbar slider friction against the keel to be a major source of VG rope resistance. Another thing that may surprise you (and I'm glad you mentioned it) is that the pulleys are not only self-lubricating Delrin (acetal) against stainless steel balls but the only maintenance these require is to be flushed with fresh water periodically in order to remove any sand, grit or dust. These are all sailing dinghy blocks and are engineered to get wet. So they are designed to be flushed with a garden hose. Spraying Sailkote into the bearing balls and races may shorten their lifespan and increase friction along the way. You have brought up a good point.

Remember--it's not as if I presented Davis with a comprehensive and thoroughly researched, annotated and citated engineering dissertation for my PhD. It's been an ongoing learning experience that gets better with time. If you have more than 100 hours on your topless glider I highly recommend learning how to remove and re-install the hinge pins so you can perform this periodic maintenance. I have to say that it's so cool to be pulling the VG rope now and actually feel the sail tension through the rope rather that just feeling a lot of friction and frustration.
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Davis
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Post by Davis »

As Steve Pearson wrote (and which I pointed to):
I asked Steve Pearson what he thought about VG maintenance. He said:

There are several thing you can do to restore the VG performance.

1. Do not use silicone lubrication. Instead use Harken Sailkote http://www.mclubemarine.com/sailkote. We have it in stock or you can probably find it online. SailKote is very lubricious and does not leave a sticky residue. It also works well on zippers, battens, etc. Clean the keel surface and as much as possible under the large plastic saddle. Spray a heavy coating on the top of the keel and let it dry before activating the VG.
You just didn't follow the links far enough.
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Post by NMERider »

Davis wrote:As Steve Pearson wrote (and which I pointed to):
I asked Steve Pearson what he thought about VG maintenance. He said:

There are several thing you can do to restore the VG performance.

1. Do not use silicone lubrication. Instead use Harken Sailkote http://www.mclubemarine.com/sailkote. We have it in stock or you can probably find it online. SailKote is very lubricious and does not leave a sticky residue. It also works well on zippers, battens, etc. Clean the keel surface and as much as possible under the large plastic saddle. Spray a heavy coating on the top of the keel and let it dry before activating the VG.
You just didn't follow the links far enough.
The missing link is: http://ozreport.com/1427719439

In the long run it turns out that one of the most significant items 'to restore the VG performance' is cleaning the hinge pins and sockets and replacing the grease--preferably with something better than 'white grease'.
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Rich Diamond
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Re:Dupont ...

Post by Rich Diamond »

How about AP303 ?
I use it on all my Harness Zippers- works great
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Re:Dupont …

Post by NMERider »

Rich Diamond wrote:How about AP303 ?
I use it on all my Harness Zippers- works great

Rich,
Are you talking about 303® Aerospace Protectant™? Assuming you are, then where exactly were you thinking about using it?
It's my understanding that it damages the stabilizing resin in woven sail fabrics and should be kept away.
I can see where it may help Nylon Zippers resist the damaging effects of UV.
But I imagine no place on a hang glider other than possibly the sail zipper coils.
Cheers,
Jonathan
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Post by Gordo »

my two cents. have we considered phenolic resin bushes. hard wearing and and a great coefficient of friction. (The material looks a bit like old fashion circuit board material)
existance is a state of mind, choose your emotion wisely
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Post by NMERider »

Gordo wrote:my two cents. have we considered phenolic resin bushes. hard wearing and and a great coefficient of friction. (The material looks a bit like old fashion circuit board material)
Hi Gordon,
In a negative load situation where the glider is tail-down into the wind and the crossbar is undergoing large cantilever stresses the load on a sleeve-type bearings may destroy them.
The pilot won't know this until airborne. Then what? The best performing bearing I can find for our application is:
http://www.mcmaster.com/#standard-sleev ... s/=13lksoy
I have had such good results with high quality grease in extreme load applications that I think I'll just stick with that and 100-hour interval inspections and re-lube as needed.
Cheers,
Jonathan
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Rich Diamond
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Re:Dupont …

Post by Rich Diamond »

NMERider wrote:
Rich Diamond wrote:How about AP303 ?
I use it on all my Harness Zippers- works great

Rich,
Are you talking about 303® Aerospace Protectant™? Assuming you are, then where exactly were you thinking about using it?
It's my understanding that it damages the stabilizing resin in woven sail fabrics and should be kept away.
I can see where it may help Nylon Zippers resist the damaging effects of UV.
But I imagine no place on a hang glider other than possibly the sail zipper coils.
Cheers,
Jonathan

Yes same stuff, i have used it on all nylon zippers, as well as VG Pulleys, & Haulback Pulleys on my Predator 142
I Never put it on my Dacron !
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Post by Gordo »

NMERider wrote:
Gordo wrote:my two cents. have we considered phenolic resin bushes. hard wearing and and a great coefficient of friction. (The material looks a bit like old fashion circuit board material)
Hi Gordon,
In a negative load situation where the glider is tail-down into the wind and the crossbar is undergoing large cantilever stresses the load on a sleeve-type bearings may destroy them.
The pilot won't know this until airborne. Then what? The best performing bearing I can find for our application is:
http://www.mcmaster.com/#standard-sleev ... s/=13lksoy
I have had such good results with high quality grease in extreme load applications that I think I'll just stick with that and 100-hour interval inspections and re-lube as needed.
Cheers,
Jonathan
My bad, should have explained a tad clearer. I meant the entire pulley(s) to be made from phenolic resin not just a sleeve.
Though as you have suggested a disassembly, clean and re-lube of steel bearings should produce min friction and extended life (I am just being lazy)
existance is a state of mind, choose your emotion wisely
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Post by NMERider »

Gordo wrote:....My bad, should have explained a tad clearer. I meant the entire pulley(s) to be made from phenolic resin not just a sleeve.
Though as you have suggested a disassembly, clean and re-lube of steel bearings should produce min friction and extended life (I am just being lazy)
For any given interval of time--say one UK season, the total work saved via reduced VG rope pull effort will be handsomely offset by the work required to do an annual hinge pin clean and re-lube.
Figure on 175 Kcal spent on the maintenance and 75 Kcal/flight saved on reduced rope pull energy spent. It only requires 3 average flights to come out ahead in the deal.
So the lazy pilot will wind up doing considerably more work in a any typical season's flying than the more maintenance-inclined pilot.

Speaking of maintenance effort versus flying benefits, I learned something very interesting about Mylar inserts and tie-down methods. I'll save it for another letter to the editor.

Cheers,
Jonathan