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Speed,Combat,Scale,Racing => Scale Models => Topic started by: Jim Roselle on September 18, 2015, 06:21:09 AM

Title: Line size question
Post by: Jim Roselle on September 18, 2015, 06:21:09 AM
If I am reading the rulebook correctly a model of 1.51-2.5lbs can fly on .012" lines and is pull tested to 5g's. Is that correct? It seems a little light to me but I'm no engineer .

Thank you,

 Jim
Title: Re: Line size question
Post by: Clancy Arnold on September 18, 2015, 08:08:50 PM
Jim
The .012 inch diameter is correct for a 1.51 to 2.50 pound control line scale model flying on multi-strand cables, either 2 or 3 lines supporting the load. 

There were many hours of engineering time that went into the new Line Size / Pull Test Chart in the revised Control Line Scale Rules.  Eight active CL Scale Contest fliers volunteered to serve on a committee to review the then current rules and make recommendations for changes.  As they each considered their own recommendations they also reviewed and commented on the recommendations from the other seven.  The CL Scale Rules as approved were the culmination of 18 months work by the committee.

Clancy
Title: Re: Line size question
Post by: Fred Cronenwett on September 18, 2015, 08:39:38 PM
I fly a 3.5 lbs model with 2 lines, .012 diameter with no problems. A model that weighs 2.5 lbs would have a line tension less than 15 lbs which is way below the ultimate or yield limit of the .012 wire. On top of that the line tension is shared between two lines which cuts the load in half.

The margin of safety on these lines exceeds 3.0 so you are in good shape. Typically the line itself isn't the weak point, the weak point is how the lines are wrapped or crimped and pull test will expose these flaws.

No worries

Fred
Title: Re: Line size question
Post by: Jim Roselle on September 18, 2015, 09:26:13 PM
Thank you gentelmen.
Title: Re: Line size question
Post by: RC Storick on October 05, 2015, 06:39:26 PM
Has the line requirements reverted back to sanity? Lets say for a 5.5 pound airplane what size lines do I need? 2 Line.
I talked to John Brodak and I was led to believe I could fly on .018 is this correct?
Title: Re: Line size question
Post by: pat king on October 05, 2015, 09:23:38 PM
The attached is from page 5 of the 2015-2016 C/L Scale rules.

Pat