Safety thong broke

[Mike Krizan]

Flying yesterday. Was flying my profile cardinal and took off very rich. Long story. Tried a figure eight and lost line tension. Was hoping it would fly out and all would be good.  Regained tension @ 10 feet and jerked my arm hard enough to pull handle out of my hand and broke my safety thong. Thong was made of braided leather.

[Dennis Toth]

Mike,
I assume the plane when in and did not get lose so the thong did it's job. The thong material needs to be looked at as you start you flying day to see if it is dried out or cracked as leather can do from sweat and ground moisture.

Good for all of us to be conscious of, thanks for bringing this up.

Best,    DennisT

[Dan McEntee]

   Leather isn't a good choice for a safety thong. I tried those early on an almost all of them broke during testing. At a contest, they should pull test the thong for the reasons that you discovered the hard way! I have resorted to using parachute cord. I bought bright orange for extra visibility is finding my handles in the grass. These should last a life time. Braided nylon boot laces work well, but small nicks and cuts will get to them over time but still last longer that leather. WHat ever you decide to try, test it yourself so you know how much abuse it will take.
   Type at you later,
  Dan McEntee

[Peter in Fairfax, VA]

Dan,

Thanks for mentioning that some contests pull test the thong.  How?

The reason I ask is that many thongs are set to pull on the down line.  Is the idea to test twice, first pull testing handle to plane, then handle to thong?

Some thongs attach via a split ring, which is also a potential point of failure.

Peter

[Donald Main]

I have done pull testing at the Nats and I always pulled tested the thong. I've seen plastic beads fly apart, thongs that were attached by a repair tag split ring and leather that was dry rotted.

[Peter in Fairfax, VA]

Donald,

Yes, I'm aware that split rings failed during Nats pull testing.  Precisely how was the testing done?

thanks,

Peter

[Peter in Fairfax, VA]

Thanks for the details and reports.  Sounds like the better technique is "pull twice," as expected.  That would be expected to catch weak thongs or their attachments, and has, based on the Nats reports. 

Is it possible that an actual strong thong jolt might affect the plane / lines differently than the two test pulls, focusing on one line and the structure of any bellcrank stop structure in the plane, but still the "double pull" style makes sense.

Peter

[Larry Fruits]

  I was one of the pull testers at this years Nat's. Two pulls are required to test the entire system. One with handle, lines and plane, the second with handle and thong. I had three thong failures this year, and surprisingly one of them was on a multinational and world champion's equipment. He was surprised too, and admitted that it was old. He repaired the thong, retested, and was good to go. Stuff happens, but all parts of the system need to be maintained.

 Blessings;
   Larry     

[Tim Wescott]

I use 1/4" clothsline, just in case my wrist is "pull tested" in flight.

[Dan McEntee]

  I was one of the pull testers at this years Nat's. Two pulls are required to test the entire system. One with handle, lines and plane, the second with handle and thong. I had three thong failures this year, and surprisingly one of them was on a multinational and world champion's equipment. He was surprised too, and admitted that it was old. He repaired the thong, retested, and was good to go. Stuff happens, but all parts of the system need to be maintained.

 Blessings;
   Larry   

   And that is why you pull test it!! My handles are all wood, and have enough area at the bottom to drill a hole to pass the cord through, with the cord melted and sealed at the end as mentioned, and then just tie an over hand knot in the end. The knot is much bigger than the hole, and it can not pull through. On the other end, I seal the cord the same way, and form a loop on it and bind the two cords together with fine wire, much mike you make up the ends on flying lines. I work my way towards the loop with the wire, and before the hole gets too small, I put the other end through the loop, then finish up the wrap a nd make the loop snug with some resistance on the cord. This is all done before you attach it to the handle. This lets you snug up the thing on your wrist, and stay that way, and then loosen it up when finished flying. After I'm satisfied with the thong loop, then I install it on the handle. I don't make the thon too long here it is in the way, or can catch on anything, but long enough so it's comfortable. No plastic beads to break  or crack and fail. I have never had one of these pull out of the handle even up over my body weight hanging on it. Small nylon cord can age, get nicked up and fail eventually, but is easily replaced. Parachute cord , I think , will last the life of the model and the person flying it!!
  Type at you later,
   Dan McEntee

[Brett Buck]

Flying yesterday. Was flying my profile cardinal and took off very rich. Long story. Tried a figure eight and lost line tension. Was hoping it would fly out and all would be good.  Regained tension @ 10 feet and jerked my arm hard enough to pull handle out of my hand and broke my safety thong. Thong was made of braided leather.

     I have found leather to degenerate pretty quickly. It's plenty strong enough when new, but mine all failed after about a year at very low loads.

  I recommend nylon bootlaces, just like you get at the notions rack at Safeway or Kroger. I think my #1 handle still has one from the 98 NATS.

  Brett

[Trostle]

Dan,

Thanks for mentioning that some contests pull test the thong.  How?


Peter

Simply pull the thong from its attachment point on the handle.  There is no need to place any load on the model control system/lines/line attachments on the handle during the separate thong pull test.

Keith

[Mike Krizan]

Leather past the sell by date. Sentimental value, was made for me by Bob Libscomb. Great builder, flier, and friend.  MK

[Brett Buck]

Leather past the sell by date. Sentimental value, was made for me by Bob Libscomb. Great builder, flier, and friend.  MK

    Great guy!


    Brett

[Ken Culbertson]

Leather past the sell by date. Sentimental value, was made for me by Bob Libscomb. Great builder, flier, and friend.  MK

Mike, I piloted Rat for Bob back in the 60's,  Evan as a nimble teenager I could barely keep up with him.  I heard that he had passed but I have no idea when or how.  Last I saw him was '66.   His planes and his pitting skills were world class.

Ken

[bob whitney]

ACE HARDWARE sells real thin pull ropes for weed eaters by the ft  .perfect for wrist straps

[Mike Krizan]

Bob is still with us. He is in an assisted living center in Georgetown Texas. Will pass along thoughts. Thanks, MK