This is "It makes Sense" Good news.  Now I can trim my 57 oz w/battery Bearcat for .015s.


linheart

Hi Linheart,

I'm glad to hear that your beautiful Bearcat is so light. Your scale plane was an inspiration to me, and got me started on my scale Extra. 

I thought the old limit was around 64 oz for .015? I flew my 59 oz plane on .015 at the last 7 contests and over 400 flights. At one contest I was too lazy to take off the Eagle Tree test equipment and flew at 62 oz. on the same lines. Maybe I had the wrong chart last year? Yikes, I'm saying this in public .... the line police may come for me now! At least I always passed the pull test. Would that be an adequate defense in USA CL?    I'm glad this correction helped you and your Bearcat! 

Hi Tim,

The reason for the change was because they made a math error in the old chart. If you look at the line size vs weight for each jump they are now in proportion to each other, as they should be. It was only the top jump that was incorrect in the past.

Going to the 10G pull test that the rest of the world has used forever was a good step in the right direction a few years ago. I just wish they would have gone all the way and just dropped the line dimension rules and only use the 10G pull test like 95% of the rest of the world uses. This would save us a lot of grief in ECL. But at least it is better now than it was last year! 

PS: Tim, you should have "PERFECT" props starting early next week! 

Warm Regards, 

This is good news.... but why did they not use the same rational for models in that maximum 64 oz category.....say extending that weight limit to 70 oz for 0.15's ??

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Well, the same rational WAS used for all weight classes. Each class was reviewed for the max pull test that would exist in each, and made sure the margin of safety  (allowable strength / appled load) was the same for all. When using that approach, it was very clear that the upper limit on 0.018" lines was too low, and needed to increase. At 90 ounces, the margin is the same as the other groups.

I was the person who was responsible for this change, so blame me if you don't think it correct. However, the CLPA rules committee approved this change.

Paul Walker

Indeed this is terrific news THANKS for taking the lead Paul!

(uhh, anyone need a set of .021x65's )

... a positive Impact ...

Maybe so.  We'll see how heavy that Impact comes out.

I have received a few e-mails on this subject, so a single response here is quicker.

The margins were calculated based on minimum breaking strength data received from Jersey Strand and Cable via AMA.

When using the upper weight limit of each range, the 10 times pull test was compared to the MBS of that size line in that range. All the margins were consistent except for the 0.018" ramge and the min line size range. Moving the 0.018" line range to 90 ounces made for a similar margin on the pull test as the other ranges.

No attempt has been made to quantify centrifugal force, or a capture of a plane that has come loose on the lines. The 10x criteria is the closest thing we have that covers that.  History has shown that there really isn't an issue with CLPA line sizes. We simply haven't had any significant number of issues.

Paul Walker