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Author Topic: Scale Nats question 2  (Read 388 times)

Offline Hemi Steve

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Scale Nats question 2
« on: October 01, 2019, 08:22:01 AM »
In the Control Line General Rules paragraph 5.1 discusses line connectors and states that "each load bearing line connector shall have a test rating equal to at least the total pull test required on the model".  it goes on to say that the "burden of proof of the test ratings of line connectors shall be the contestant's responsibility".

I typically use the extra large Brodak connectors as in the attached picture.  Brodak does not specify a proof load on this style connector.  My LHS owner says AMA does not allow this type but I see no such prohibition in the rules.

Assuming these are allowed does the successful control system pull test satisfy the burden of proof of an adequate test rating"?

In a related area, Miss L.A. has plug-in wings and the lead outs need to be disconnected from the bellcrank to facilitate the wing removal and to clean up the exterior for static judging.  To facilitate this I have fabricated a 0.062" piano wire elongated loop with a bound and soldered closure that connects to the bellcrank.  The loop can be extended to the outside of the fuselage where the extra large Brodak connector is used to fasten the leadouts.  I have tested these to the required 5g pull test for this model.  So, the same question as above.

See pictures.

Thanks

Steve



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Offline john e. holliday

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Re: Scale Nats question 2
« Reply #1 on: October 01, 2019, 10:20:47 AM »
I quit using those slide connecters years and years ago.   Lee Machine Shop makes a tool for making line connecters and also has the required wire.   I've seen too many planes lost with those slide connecters when not closed properly.  If you browse this forum you will see what they look like. D>K
John E. "DOC" Holliday
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Offline chuck snyder

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Re: Scale Nats question 2
« Reply #2 on: October 01, 2019, 11:21:33 AM »
Steve,
I have been flying a Typhoon and Henschel 129 that both weigh 15#. I use terminations made by wrapping with copper wire. That is what was in the rule book 60 years ago when I started flying control line. Never bothered to change. Both those models have connectors without the slide. Supposedly they are better, and I have a bunch.

My models have always been given a pull test at the Nats, but I do not recall ever having the line diameter checked with a micrometer or having the terminations inspected.
Chuck

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #3 on: October 01, 2019, 12:51:37 PM »
Doc
I have one of the connector tools and I have used them on my 45 oz stunters using the 0.051" wire.  They look awfully light for a 10+ lb plane.  I'll do a pull test on one and see how they fare.  Brodak sells some heavy proof load clips similar to the ones you can make with the Lee Machine tool.  I have found that they can get crooked on the "double hooked" end...I don't like that.

Chuck
I've seen pictures of your Henschel....very very nice to say the least.  Where do you get your connectors?

Steve

Offline chuck snyder

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Re: Scale Nats question 2
« Reply #4 on: October 01, 2019, 04:01:50 PM »
Steve, I have had the connectors for years; no telling where i got them. Try this website; they may be the "squeeze" connectors listed. http://www.mbsmodelsupply.com/Catalog.pdf
Chuck

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #5 on: October 01, 2019, 06:22:09 PM »
Thanks Chuck
They have a lot of the little bits and pieces that you can't typically find at the LHS.  I'll get some of them.  Pretty inexpensive as things go.

Steve

Offline T.J. Vieira

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Re: Scale Nats question 2
« Reply #6 on: October 02, 2019, 06:19:21 AM »
General rules section 5 sates that no more than two connectors shall be used per line.  This is there to allow for connections on either side of your flying wires.  not sure if an additional connector at the bellcrank would fly, and would likely fall under whether the judges found it suitable.  that being said, if you were to switch to solid leadouts, and button bellcracnk, you'd probably be OK.

the slide connectors you show are "allowed" by the AMA, however, the confusion comes down to the wording of the rules, and with the CD having final say.  if he doesn't like them, they aren't going to be allowed.  if he does, they are fine.  i know people who use them, i prefer the "Hawaiian snaps" however.

burden of proof is during pull test.  And, if there were a failure of the snap (any type) during a flight causing damage (insurance claim) or DQ from the contest (rules violation), you'd need to prove that you were using the correct hardware.

Offline Paul Smith

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Re: Scale Nats question 2
« Reply #7 on: October 02, 2019, 07:32:12 AM »
I quit using those slide connecters years and years ago.   Lee Machine Shop makes a tool for making line connecters and also has the required wire.   I've seen too many planes lost with those slide connecters when not closed properly.  If you browse this forum you will see what they look like. D>K

While above is true, there are also many failures due to the (preferred) scissors type clips getting twisted out of position and shortening one line. I have NEVER had the slightest problem with slide clips, other than over-zealous event directors with a scissors clip fetish.

It would be cheap and easy enough to set up a test rig with a short sample your intended leadouts, clips and flying lines.
Test this to failure. 
I would wager that the flying lines will break before ANY clip.
Paul Smith

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #8 on: October 02, 2019, 08:04:35 AM »
T.J. Thanks for the reply.

I read section 5 and thought about its meaning/purpose regarding the limit of 2 connectors per line.  Here's my thoughts:

1. I would distinguish between control lines and leadouts where control lines go from the handle to the model (wing tip) and leadouts go from the bellcrank to the control lines.

2. I think the purpose of the 2 connector limit is to prevent a contestant from adjusting the length of a control line by connecting multiple segments together.

Regarding the button style bellcrank:  I've never actually seen one but I've seen pictures and read about them and it seems like they are mostly used on smaller race planes I've not read anything about their use on large models.  As I understand them, they provide a bolted connection between the leadouts and the bellcrank and provide reduced wear and friction in the connection.  I'm not sure why you would have to use solid leadouts. At the end of the day it is a removable connector that needs a tool rather than fingers to disconnect.  Also, I've not found a commercial source for button bellcranks other than perhaps the  unit being sold in the Stunt Hangar Store as the "New Bellcrank"

I have no problem making a button bellcrank and using that design to dismount the leadouts if necessary.  it just adds complexity to the task.

Finally, what is a Hawaiian snap connector?

Thanks

Steve

Offline T.J. Vieira

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Re: Scale Nats question 2
« Reply #9 on: October 02, 2019, 12:12:19 PM »
button cranks are also used on speed planes, they can certainly handle a bit of force (think of a D speed...!)  the solid wire leadout allows for the little bit of "spring" needed to mount/dismount them as needed.

the Hawaiian snaps are the "scissor connectors" most people prefer.  the only real issue with them is if you are using the wrong size eyelet for them, they can kinda "kink up" by letting the eyelet move around.  i always grab both lines when heading to the center, tugging on it a bit to make sure they stay "set" out of an over abundance of caution.  i've never had an issue with those, but have had the slide connectors come loose on my before (discovered after landing).

Online bill bischoff

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Re: Scale Nats question 2
« Reply #10 on: October 02, 2019, 02:32:24 PM »
In answer to the original question, the big slide connectors sold by Perfect (and others) are rated 49 lbs. If your pull test is less than 49 lbs, you are OK per the rule book. For your own satisfaction, fill a bucket with 49 lbs of something, connect to your handle with the clip in question, and lift. It will either hold or fail. This is more accurate than trying to measure it with a spring scale.

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #11 on: October 02, 2019, 04:14:29 PM »
Bill,
I tested one along with a scissor connector that I just made on my bending jig.  My spring scale only goes to 50 lb as up to this point we only fly up to 40 size stunters at my club. Anyway, both the Brodak "extra large" slider and my formed scissor connector made with 0.047 piano wire passed a 50 lb pull with no hint of deformation.  So, my measured 50 lb proof test would equate to a 100 lb pull test on a 2 line model.  I was surprised how strong the 0.047" piano wire connectors are. I have them on a couple 45 oz stunters and they easily pass the 10 g pull.

Steve

Online bill bischoff

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Re: Scale Nats question 2
« Reply #12 on: October 02, 2019, 06:58:33 PM »
Please reread your first post. Each line connector must be rated for the ENTIRE pull test, not just its own portion of the pull test.

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #13 on: October 03, 2019, 06:18:00 AM »
Thanks Bill
You are right...My bad.  The devil always resides in the details.  I guess I need to get a bucket of gravel to test connectors.

Steve

Offline Hemi Steve

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Re: Scale Nats question 2
« Reply #14 on: October 05, 2019, 06:31:47 PM »
All
Thanks for all of the terrific feedback in my questions.  Based on the responses I'm going to switch from slider line connectors to scissor (pinch) connectors. Amoment of inattention to the details and leaving a connector open could have a bad outcome.  I will also switch from crimped terminations to the wrapped terminations as depicted in the general rules as figure 3 on page 8.  I also believe I have a solution for the leadout connection to the bellcrank that will allow me to easily remove the plug-in wings and also be able to display the model for static judging without seeing the leadouts or the leadout guide without an added connector.

To accomplish this  I will open up the holes in the adjustable leadout guide slider so that the leadout eyelets can be fed through. The openings in the fuselage sides are already large enough to deal with the arc of the lines as the bellcrank moves through its arc and can clear the eyelets.  For static display I will simply coil the leadouts inside of the fuselage.  The top hatch is very large and I can easily do this.  The leadout guides are already removable for static display.  10 minutes in the milling machine will do it.  I will now be able to permanently connect the leadouts to the bellcrank and do a wrapped termination.

Thanks to everyone who gave this problem some thought and offered their ideas.  This forum is great for this kind of interaction.

Steve


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