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Author Topic: Spectra lines for stunt  (Read 6217 times)
Steve Helmick
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« Reply #50 on: November 30, 2016, 09:28:26 PM »

"We need real life experience in the stunt competition arena to really learn what spectra can or cannot do for us."

How do we get "real life experience in the stunt competition arena" when it's not legal to use in competition? How do you propose measuring the diameter of Spectra line?

Just looking for practical answers to both questions!  Hoff Steve
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

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Brett Buck
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« Reply #51 on: November 30, 2016, 11:20:38 PM »


What would be required? Per the CL General rules on applicability of spectra lines:

5.3.5.1 Spectra Lines Lines made of Spectra fiber, made of gel spun ultra-high molecular weight polyethylene are permitted for sport flying and demonstration purposes. Spectra lines are not permitted in competition unless the specific rules for the event flown expressly permit such use. The use of high visibility yellow lines is recommended, but not required. For sport and demonstration flying with two lines, Spectra lines shall have the following strengths:
 
Aircraft           Engine             Watts         Rated 
Weight       Displacement                        Spectra St.
 24 oz.              .09                 300        20 lbs. .010
 40 oz.              .25                 450        40 lbs. .013
 64 oz.              .40                 600        60 lbs. .016
 75 oz.              .75                 750      100 lbs. .018 


For stunt that would mean adding a sentence to Section 4.1 to specifically allow spectra then adding in the spectra line table from the CL General rules Section 5.3.5.1 into the line size table Precision Aerobatics rules.




   I am not sure how you would use the diameter, since it's not really round and it's not of constant cross-section. Do we put a micrometer on the lines and DQ someone for going under?

      Brett
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Jim Svitko
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« Reply #52 on: December 01, 2016, 05:12:39 AM »

The boxes of Power Pro brand Spectra show an "EQ. DIA." value.  I did not know what that EQ DIA meant but it was explained in another thread as equivalent monofilament diameter for reel capacity purposes.  Nevertheless, these numbers might still be of use to us.

When I measure the 50 lb. (12 EQ. DIA.) line I have, I measure 0.012 as soon as I feel resistance.  I can push a bit more and compress the line to 0.011.  The 65 lb. (16 EQ. DIA.) measures 0.016 and I can compress it to read 0.015.  So, it appears that we can still get an accurate enough measurement to determine line size, as the chart shows in the general rules.

These values vary slightly along a length of line but I do not see that it is enough to matter.

I have not tried any of the inferior clones of Spectra that we have been warned about.  Maybe the inferior products will produce different measurement results.  If so, then that might be a way to identify them.  Also, I have not tried any other brand of Spectra, of reputable manufacture, other than Power Pro.  Do other manufacturers have a different EQ DIA value for a given test rating of line?  The fishermen among us might have some experience here with different brands.



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Dennis Adamisin
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« Reply #53 on: December 01, 2016, 09:18:16 AM »

The Combat guys are couple years into this - they have experience on whether there is a measurement issue and how to deal with it.
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Denny Adamisin
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Brett Buck
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« Reply #54 on: December 01, 2016, 09:54:17 AM »

The Combat guys are couple years into this - they have experience on whether there is a measurement issue and how to deal with it.

    There *is* an issue - just look at the stuff. I would suggest removing the diameter specification entirely.

     Brett
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Jim Carter
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« Reply #55 on: December 01, 2016, 01:22:53 PM »

Per the CL General rules on applicability of spectra lines:

5.3.5.1 Spectra Lines made of Spectra fiber, made of gel spun ultra-high molecular weight polyethylene are permitted for sport flying, demonstration and competition.  The use of high visibility yellow lines is recommended, but not required.  Spectra lines shall have the minimum strengths as follows:
 
Aircraft           Engine             Watts         Rated 
Weight       Displacement                        Spectra St.
 24 oz.              .09                 300        20 lbs. .010
 40 oz.              .25                 450        40 lbs. .013
 64 oz.              .40                 600        60 lbs. .016
 75 oz.              .75                 750      100 lbs. .018 

Hi Dennis!  I'm not much of a formalist but why can't the proposal/rule be written as above??  If there's any question, it could only be "proving" that a specific set of lines are truly Spectra versus some knockoff product that can only be chemically analyzed being one molecule from the "brand" named product and I doubt anyone would go through that level of analysis for even FAI competition!!
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Jim Svitko
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« Reply #56 on: December 01, 2016, 06:47:32 PM »

A suggestion, for what it is worth:

The Pull Test table in paragraph 5 of the CL Stunt rules provides information on steel line requirements.  Nothing in the table about engine displacement or watts.  The pull test is determined by model weight.

The table can be expanded for Spectra lines.  In place of "Required Minimum Diameter of Each Line (in)" we would put "Required Minimum Test Load Rating (lb).  There would be no need for "Single Strand" or "Multi-Strand" headings for Spectra.  The model weight divisions can remain as they are.  And, since Spectra line diameter is, apparently, of limited use for our purposes, no heading needed for diameter, either.  Although the Spectra diameter might be considered useless for our purposes, it could serve one function:  it might help verify the test load rating of the lines in use.  It might be difficult to determine that just by looking at them.  Even though the measurement is not as precise as for measuring steel lines, it may be precise enough to determine if the line is 40 lb., 50 lb., 65 lb., etc.

Spectra minimum required strengths are given in paragraph 5.3.5.1 of CL General rules.  Maybe these values are good enough to be used in the table in paragraph 5 of the CL Stunt rules for Spectra lines.

Maybe this is not an ideal solution but it is the only thing I can come up with right now.

Thoughts, anyone?  
« Last Edit: December 04, 2016, 09:52:30 AM by Jim Svitko » Logged
Don Coe
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« Reply #57 on: December 02, 2016, 04:51:04 AM »

Jim - That seems like a sound reasonable approach.  How can we get behind this and move it forward?
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Phil Krankowski
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« Reply #58 on: December 02, 2016, 07:55:57 AM »

While you are at it can you add in 15# and 10# for 1/2a, keeping at 40g for two lines
15# would be AUW of 12 oz
10# would be AUW of 8 oz

((#test_rating) * (2 lines) * (16 oz/lb)) / (40 g) = AUW in oz

Everything is pulled to 10g so there should be no concerns with this at all. 

I have hesitated to go below 20# for sport flying since it isn't listed.

Phil
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john e. holliday
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« Reply #59 on: December 03, 2016, 08:28:44 AM »

Jim - That seems like a sound reasonable approach.  How can we get behind this and move it forward?


Make a proposal and then contact your district person on the rules board for control line aerobatics.  Of course when I was a member of the board I got more responses from out side my district. Head bang
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« Reply #60 on: December 04, 2016, 01:10:53 PM »

What about 80 lb test. No 60 powered plane can snap 80 lb test spectra lines. Actually, this question is academic because, I've got 150 yards of 80 lb test coming.
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Milton "Proparc" Graham
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« Reply #61 on: December 08, 2016, 10:47:55 PM »

Well, I'm still curious how you'd work this. If you can't reliably measure the OD, are you just planning on accepting the contestant's statement that "this here line is 50 lb test" (whatever you put on the chart for the weight of his plane)? Isn't this pretty much like what the FAI does, allowing anything that will pass the pull test? Is that good enough to suit your idea of what's safe? Would it have an effect on our AMA insurance? Etc.....  Huh Steve

PS: Bravo, Milton! I hope you have good luck and find some good methods and data to make a proposal to the CLCB. 
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.
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« Reply #62 on: December 09, 2016, 05:31:13 AM »

Even if the diameter COULD be measured, as with steel lines, it still falls back on the pull test anyways.  Lines can be damaged and damage overlooked surprisingly easily. 

Phil
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john e. holliday
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« Reply #63 on: December 09, 2016, 10:57:36 AM »

I too think a pull test should do it.   I know cable if pulled enough times will have smaller diameter in places.   At one NATS a set of lines was measured in four places before it was declared legal.  The lines were also pulled to 100 pounds.   Another case was lines measured great but failed pull test when bell crank tried to come out the wing tip on a 35 pound pull.


At Tulsa this year I flew a plane on .018 cable instead of .015 cable it usually flew on.   Reason was the contest required them.   The plane will now fly on .018 lines as I had better feel from them. Hoff
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John E. "DOC" Holliday
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Steve Helmick
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« Reply #64 on: December 11, 2016, 09:03:43 PM »

At Tulsa this year I flew a plane on .018 cable instead of .015 cable it usually flew on.   Reason was the contest required them.   The plane will now fly on .018 lines as I had better feel from them. Hoff

Doc, seems like there must be something else going on here. Was the airplane close to weight break where the next bigger size wire was required? If so, this is a problem of plane's weight and not that "the contest required them". IMO. Did the plane gain weight or was the official scale just different than yours?  Hoff Steve
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.
john e. holliday
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« Reply #65 on: December 12, 2016, 11:34:58 AM »

No, the problem was I didn't read the rules close enough.   
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« Reply #66 on: December 12, 2016, 12:44:58 PM »


 with the ok of the CD and all the other flyers ,one set of Brodak spectra type lines with crimped ends around a grommet and two sets of spectra lines with tied loop ends were used with no problems at the KOI
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john e. holliday
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« Reply #67 on: December 12, 2016, 12:49:57 PM »

Hope some one got a picture of them.
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John E. "DOC" Holliday
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« Reply #68 on: December 13, 2016, 05:26:12 PM »

No, the problem was I didn't read the rules close enough.   

Doc, you're making it sound like the contest management arbitrarily required everybody to fly "stunt" on .018" lines. Nobody would do that! So, what are the details? Were you flying an event other than stunt?  Huh  Hoff Steve
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In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.
phil c
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« Reply #69 on: December 13, 2016, 06:43:05 PM »

Phil, what soap/detergent do you use?  My oldest lines are getting oily  and they tend to stick together when wet. 
Nope.  If the lines get too dirty you can wash them off in water.  Grin 

Dirt will cause more abrasion, but the new line has a coating on the fibers so it takes quite some time for it to start showing signs of abrasion.  When you start seeing fuzzies it is time to retire the set of lines.

Phil

Phil has a good point.  Oily dust and dirt don't help anymore than they do on steel lines.

An  additional point to watch out for- don't run both lines through one LO guide.  It ends up making the line rub each other and the leadout guid all the time.  They can wear out quicker.  Nylon eyelets, especially if the sharp, molded edges are rounded, takes much longer to wear the lines.  The lines will still start to show 2-3in. where some of the braid start to show and eventually some fibers start to fray.  At that point either cut the lines down or start pull testing them individually to make sure they will still withstand at least 50% of the rated strength.
Unlike steel lines which can take a pull test even if they are fatigued and then break in flight, the Spectra seems to fail more gracefully.

Phil
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« Reply #70 on: December 14, 2016, 02:10:03 PM »

Doc, you're making it sound like the contest management arbitrarily required everybody to fly "stunt" on .018" lines. Nobody would do that! So, what are the details? Were you flying an event other than stunt?  Huh  Hoff Steve

This was not a stunt contest.  It was an event for their first Vintage Combat get together.    Hoff
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I was always taught to respect my elders, but it keeps getting harder to find one.
Today I broke my personal record for most consecutive days lived.
John E. "DOC" Holliday
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Steve Helmick
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« Reply #71 on: December 14, 2016, 04:33:53 PM »

Thanks for clearing that up, Doc. I believe Combat flew on .015" cables when I flew the event (mid-'60's), but has required .018" cables for quite awhile now. It would be required for Vintage Combat for insurance reasons; seems justifiable and unavoidable.  Hoff Steve

« Last Edit: December 15, 2016, 10:40:30 PM by Steve Helmick » Logged

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.

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