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Author Topic: Control Line Length Rules/Interpretations  (Read 5588 times)

Offline Jim Carter

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Control Line Length Rules/Interpretations
« on: April 22, 2015, 08:19:16 AM »
Fellow pilots!  Believe me, I'm not trying to start an argument because I understand and can accept the "rules are the rules" position, so to speak. However I truly don't understand the basis for the rule as currently interpreted. This interpretation can be/is a really expensive one for those who fly different types and classes of model airplanes. It's difficult for me to believe that all many of the really good pilots and even the ham-handers like me have a dedicated set of lines and handle for each plane. Am I wrong in this belief??

As I have read and understood the previous and current rules, the lines themselves were to be 35', 52', 60' etceteras. As a result, for the purpose of flight/calculating speed, the c/l of the plane to c/l of the handle dimension were to be taken into the measurement consideration. I mean that makes sense, know what I mean?? Besides, that's how the lines are marketed and sold commercially!!

However the other interpretation almost demands that a pilot must have a "dedicated" set of lines for each plane given the differences in wingspans and even the differences in handles. If this is true the lines manufacturers should/would be selling lines measured to the 1/4" to comply with the existing interpretation, wouldn't they?

I just think it's highly inefficient and fiscally wasteful because, in theory, I could build a couple of planes, one with a 48" wingspan with dedicated lines and handle and a backup plane with a 50" wingspan. Based upon the rules interpretation, technically, if I were to I crash the primary, plane those same lines could/should not be used on the backup plane at a contest. Am I correct in formulating my example??

Is there anything that can be done to modify or clarify the rule, as written or is this something "written in stone"?? Has the rule ever been challenged at a major contest or say, the NATS??

Jim

 


Offline john e. holliday

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Re: Control Line Length Rules/Interpretations
« Reply #1 on: April 22, 2015, 08:29:25 AM »
Don't know what you are starting here, but I have had one set of lines for stunt/sport depending on engine size of the plane.   Now the other competition events have set center to center requirements for the events(carrier, combat speed and racing).   Stunt has a maximum length.   Think there is a minimum but haven't seen it.   So me not being a top 40 at the NATS I have maybe three sets of lines, some times four, depending on the contest.    So now would you fly your 60 size ship on the same lines as your 25 size plane? VD~ S?P
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Offline Tim Wescott

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Re: Control Line Length Rules/Interpretations
« Reply #2 on: April 22, 2015, 08:52:05 AM »
I just think it's highly inefficient and fiscally wasteful because, in theory, I could build a couple of planes, one with a 48" wingspan with dedicated lines and handle and a backup plane with a 50" wingspan. Based upon the rules interpretation, technically, if I were to I crash the primary, plane those same lines could/should not be used on the backup plane at a contest. Am I correct in formulating my example??

Could you point to the specific rules you're talking about, and what class of competition you're engaged in?  This is not a big issue in Stunt because -- even putting aside the fact that the lines and handle are part of the package that you trim -- there's a very generous maximum and that's it.  For all other classes of competition the line lengths matter because it influences how well you do against your competitors.

You can save a lot on lines if you buy the stuff you need from Melvin Shute (MBS Model Supply).  You'll be paying something like $6 per line set.
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Offline Jim Carter

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Re: Control Line Length Rules/Interpretations
« Reply #3 on: April 22, 2015, 09:03:59 AM »
Don't know what you are starting here, but I have had one set of lines for stunt/sport depending on engine size of the plane.   Now the other competition events have set center to center requirements for the events(carrier, combat speed and racing).   Stunt has a maximum length.   Think there is a minimum but haven't seen it.   So me not being a top 40 at the NATS I have maybe three sets of lines, some times four, depending on the contest.    So now would you fly your 60 size ship on the same lines as your 25 size plane? VD~ S?P
L.O.L.!!  Hi Doc!  I guess I'm not communicating effectively, allow me to attempt to clarify what I'm facing.  As a matter of fact, I may even be posting in the wrong forum and if so, please forgive me and I would ask the moderator to move it to the appropriate forum.  In say AMA Profile Scale; the rules state:

"4.8.3. Control Line(s). The length of the control line(s) measured from the center point of the grip part of the control handle (device) to the fore and aft center line of the model shall be as specified in the CL Scale line size and pull test table. CL Scale Flying Table: Line Length and Size, and Pull Test Requirements
*Models weighing 1.5 pounds or less must use a minimum line length of 52-6‖ unless the total engine displacement is less than .130 cubic inches for a single-engined model, or the displacement of each engine of a multiengine model is less than .065 cubic inch. In such cases, minimum line length may be 35 feet."

In the General Section: "5.2. The length of the control system is measured from the center point of the grip part of the control handle (device) to the fore and aft center line of the model. All speed computations are to be based on the lengths specified for the event, and no allowance is to be made where lines used exceed those lengths."

On the face of 5.2, if the event specifies 35' lines c/l of plane to c/l of handle, and I have one plane with and 18" wingspan and another with 28" wingspan, based upon both of the rules as written, wouldn't I be required to have two sets of lines??  I recognize stunt and sport do not have the same restriction and that was not the basis for my inquiry .... I regret the confusion.

Offline Dane Martin

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Re: Control Line Length Rules/Interpretations
« Reply #4 on: April 22, 2015, 09:53:08 AM »
I think it's easier than that. I think in stunt or scale it's more like a min of 35' for small and a max of 70' . i think if you wanna go anywhere on between for power or lap times, that's up to the pilot.
I'm learning the speed side of it now, with one contest under my belt. Those seem to be much different so far requiring solids and what not. Like my 1/2A proto was on 42' lines. Kinda a weird length. So you just have to build your plane around that idea. I'm pretty fresh to CL competition, but this is how I'm seeing it so far.
 My first stunt contest, i used 60' .018s on an S1 ringmaster. Totally legal, but i probably could have made a better choice.

Offline Tim Wescott

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Re: Control Line Length Rules/Interpretations
« Reply #5 on: April 22, 2015, 10:27:29 AM »
In the General Section: "5.2. The length of the control system is measured from the center point of the grip part of the control handle (device) to the fore and aft center line of the model. All speed computations are to be based on the lengths specified for the event, and no allowance is to be made where lines used exceed those lengths."

On the face of 5.2, if the event specifies 35' lines c/l of plane to c/l of handle, and I have one plane with and 18" wingspan and another with 28" wingspan, based upon both of the rules as written, wouldn't I be required to have two sets of lines??  I recognize stunt and sport do not have the same restriction and that was not the basis for my inquiry .... I regret the confusion.

You can run longer lines in speed.  No one will say no.  They'll say "yes" with a smile and they may even snicker a bit.

Your speed is computed from your lap time (actually from your cumulative time for some number of laps, which ones are used varies from event to event) and a formula that assumes your lines are the minimum length.  If you run longer lines your computed speed will be lower than your actual speed by the same proportion as your lines are longer.

If you're serious about speed then handles and lines would be the least of your expenses, so I'm not sure where your worry is.
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Offline Jim Carter

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Re: Control Line Length Rules/Interpretations
« Reply #6 on: April 22, 2015, 10:42:05 AM »
You can run longer lines in speed.  No one will say no.  They'll say "yes" with a smile and they may even snicker a bit.

Your speed is computed from your lap time (actually from your cumulative time for some number of laps, which ones are used varies from event to event) and a formula that assumes your lines are the minimum length.  If you run longer lines your computed speed will be lower than your actual speed by the same proportion as your lines are longer.

If you're serious about speed then handles and lines would be the least of your expenses, so I'm not sure where your worry is.
Hi Bro Dane and Tim!  What you've written is correct and you may well be correct that I should not worry about the line lengths as a general rule.  I just wanted to be as "politically" correct as possible.  Mr Dan McEntee just wrote a very thoughtful and informative answer to my question on this same subject.  I just wanted to be comfortable and in compliance for any event participation.  Thanks guys!

Offline Brett Buck

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Re: Control Line Length Rules/Interpretations
« Reply #7 on: April 22, 2015, 11:17:56 AM »
On the face of 5.2, if the event specifies 35' lines c/l of plane to c/l of handle, and I have one plane with and 18" wingspan and another with 28" wingspan, based upon both of the rules as written, wouldn't I be required to have two sets of lines??

   Yes, if you connect to leadouts, you would need separate sets of lines, tailored to the airplane. For speed you are usually connecting the lines directly to the crank button, so it doesn't matter, or if you use internal leadouts, you can make them all the same length. The combat guys usually use leadouts, but you can make them as long as you want, so you can make them all the same.

  In stunt, of course you can use anything you want between the limits. I usually carry 4 sets of lines for each airplane - 2 of the "normal" length (whatever I have decided on as the baseline) one for the prime and one as the backup, then a set 1 foot or so shorter and a set 1 foot or so longer. I also *usually* carry 2 handles, one for the prime lines and one for the backup lines. Even though I build my lines as close to equal as possible, sometimes they wind up 1/64 or so different, so I adjust the handle for one set of lines and leave them like that. If I make an adjustment on the "prime" handle (spacing, overhang, or neutral) I transfer the same change to the backup.

    If push comes to shove I can usually switch handles and fly with whatever neutral I end up with, but it's usually better to have it one to one. I lost my handle for a while at the 2006 NATS and flew my first official flight with the Skyray handle, and it felt OK, but a little "soft". When I located my other handle, I found it was something like 1/2" narrower and the neutral was off by 1/16" - both of which are FAR larger than the changes I had made earlier in the week to compensate for the air. Ted and I also flew at the ARF-Off with the neutral off by something like 1/4" without knowing about it, and I thought it flew "OK" and Ted couldn't quite put his finger on it, but the airplane felt a bit "squirrely". That was in the flyoff and we were 1-2 in the contest with a dreadful airplane - which goes to show you how much you can overcome with sufficient concentration.

     Brett

Offline Trostle

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Re: Control Line Length Rules/Interpretations
« Reply #8 on: April 22, 2015, 05:24:07 PM »
 I guess I'm not communicating effectively, allow me to attempt to clarify what I'm facing.  As a matter of fact, I may even be posting in the wrong forum and if so, please forgive me and I would ask the moderator to move it to the appropriate forum.  In say AMA Profile Scale; the rules state:

"4.8.3. Control Line(s). The length of the control line(s) measured from the center point of the grip part of the control handle (device) to the fore and aft center line of the model shall be as specified in the CL Scale line size and pull test table. CL Scale Flying Table: Line Length and Size, and Pull Test Requirements
*Models weighing 1.5 pounds or less must use a minimum line length of 52-6‖ unless the total engine displacement is less than .130 cubic inches for a single-engined model, or the displacement of each engine of a multiengine model is less than .065 cubic inch. In such cases, minimum line length may be 35 feet."

In the General Section: "5.2. The length of the control system is measured from the center point of the grip part of the control handle (device) to the fore and aft center line of the model. All speed computations are to be based on the lengths specified for the event, and no allowance is to be made where lines used exceed those lengths."

On the face of 5.2, if the event specifies 35' lines c/l of plane to c/l of handle, and I have one plane with and 18" wingspan and another with 28" wingspan, based upon both of the rules as written, wouldn't I be required to have two sets of lines??  I recognize stunt and sport do not have the same restriction and that was not the basis for my inquiry .... I regret the confusion.

You are correct, you are not communicating effectively and you seem to be confused.  (Your "examples" make no sense.)  If you are talking about scale rules and line lengths for scale, then take this discussion to the scale section of this forum.  From those scale rules that you quote, please note that the "minimum line length may be 35 feet."  That rule does not require the line length to be 35 feet for that class of scale models using no more than 1cc engines.  If you are interested in CL scale, then pay attention to the control line requirements in the scale rules.  The "speed computations" as referenced in the General Section 5.2 that you referenced have no bearing on the scale CL rules.  The CL General line measurements do apply in that they define the line length as determined from the center of the handle and the centerline of the model.

Yes, there is a minimum line length also specified in the CLPA rules which is 25 feet.  This was adopted from the FAI F2B rules, where line length is determined in the same manner - center of the handle to centerline of the model.

Please note that in CL scale, the line length for all models, except for the 1cc powered models, can be up to 70 feet.  For the 1cc models the maximum line length is 52.5 feet.  So for your small 1cc (or less) powered scale model, the lines do not need to be only 35 feet.  They can be up to 52.5 feet.

Now, welcome to the world of "serious" control line flying where most "serious" control line flyers WILL have a dedicated set of lines for each individual model he flies.  In CLPA, part of the trimming process is to try various lengths of lines to get the best feel for the model.  This may take several sets of lines in as little as 6" increments.

For CL scale, the line length is not as critical, but still a better "feel" or a better flying airplane might be achieved by trying several sets of lines in say up to 2 foot increments.  On the other hand, commercially available lines cut to length can usually be found for your CL model given the possible range of models/power/size etc.  These commercially available lines will result in whatever the total line length will be as measured from the center of the handle to the centerline of the model.  That is just one of the facts of life one lives with when using commercially available lines with prepared ends.

In the overall scheme of things/cost of the model, having several sets of lines available to fly a certain model should not be too much of a financial overload to the modeler.

So what is it that you want modified?  For what event?  Are you talking about the CL General rules.  (These have been in effect in their current form for many years.)  Are you talking about the CL scale rules?  (These seem to be reasonably clear.)  You mentioned calculating the speed of the airplane.  Do you think for some reason that is important for CL scale or for CLPA.  (You know that this is a stunt forum that just happens to have a CL Scale column where your question/comments should probably be posted.)

Keith

Offline Howard Rush

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Re: Control Line Length Rules/Interpretations
« Reply #9 on: April 22, 2015, 06:01:29 PM »
My guess is that Jim is misinterpreting the definition of minimum.  All AMA events have generous tolerances from shortest permitted to longest permitted. 
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Offline Bill Little

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Re: Control Line Length Rules/Interpretations
« Reply #10 on: April 22, 2015, 06:44:29 PM »
Hi Jim,

You alluded to having a set of lines for each model.  In my case I do make up a set of lines and pick a handle whenever I get a new model ready to fly.  The original length is just a guess based on what length other similar models liked, and with maybe a foot added to it.  I expect to shorten the length of the lines so I start longer.  Once everything is settled, I use only these lines on this model.  When I did go to the NATS I would have a back up set made as identical as I could.  The line sets are all kept in individual zip lock bags and marked in Magic Marker as to which plane they are for.

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Offline Fred Cronenwett

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Re: Control Line Length Rules/Interpretations
« Reply #11 on: April 26, 2015, 06:54:40 AM »
The larger CL scale models that are 8 lbs and heavier require lines between 65' and 70' long center to center. The lighter models 1.5 lbs to 8 lbs have a 52' 6" minimum with a 70' maximum length. The line diameters change based upon weight and number of lines so in CL scale it's difficult to have one set of lines for all of your models. It is up to the pilot to decide how long they want the lines to be within those ranges.

I fly with a dedicated set of lines per model so I am not adjusting neutral elevator every time I fly the model. Once they are adjusted and the model is trimmed I attach the lines and I am ready to go. One connector stays on the model, the other connector stays on the lines.

This does mean I have invested some time making handles to support the numbers of lines that I have but it was worth it. I also adjust the line length to best fit the model like Kieth and others have suggested.

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Offline Jim Carter

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Re: Control Line Length Rules/Interpretations
« Reply #12 on: April 26, 2015, 07:41:26 AM »
Thanks Big Bear!!  Thanks Fred!  You and some of the others have been so patient and I've learned somethings I did not know!!  I really appreciate all of you being so patient and understanding.  Here I am, 66 and never knew it was acceptable, "normal" and essentially necessary to have more than one set of lines!  All these years .... I have maintained one each 35', 42', 52', 60' and 65' lines which I've flown my various planes and replaced as necessary along with a handle for each (the 35', 42' and 52' use the same handle and the 60' and 65' use the same handle).  Well, now I know!!  Thanks guys!

Offline Tom Foster

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Re: Control Line Length Rules/Interpretations
« Reply #13 on: January 02, 2018, 01:42:07 PM »
I just found this discussion and I think it is relevant to the Sportsman Stunt Speed event, the 'rules' for which specify 59' 6" line length.  So, if I interpret the discussion correctly 60' lines could be used if I/we accept the (minimal) reduction in speed effected by the longer lines on our lap time. Right? Wrong?

Online Paul Smith

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Re: Control Line Length Rules/Interpretations
« Reply #14 on: January 02, 2018, 02:26:02 PM »
In Stunt & Scale the overline length limit, 70' true, is the only rule that matters.

If interchangeability is your issue, simply create your own personal leadout length standard and build all your models to that standard. 

In events that hinge on speed (combat, speed, racing and carrier) the contestant strives to use the shortest lines that are legal for the event. 

The cost of wire is trivial in comparison to other costs in The World of Control Line.
Paul Smith

Online Paul Smith

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Re: Control Line Length Rules/Interpretations
« Reply #15 on: January 02, 2018, 02:30:00 PM »
I just found this discussion and I think it is relevant to the Sportsman Stunt Speed event, the 'rules' for which specify 59' 6" line length.  So, if I interpret the discussion correctly 60' lines could be used if I/we accept the (minimal) reduction in speed effected by the longer lines on our lap time. Right? Wrong?

Correct.  I set the limit at 59'-6" to be consistent with Foxberg Racing, Combat, and other events that allow the contestant +/-6" of tolerance.  In a "pure speed" world I should have said "60-feet minimum", but I am trying to get along with the other evenst at The Brodak.
Paul Smith

Offline Trostle

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Re: Control Line Length Rules/Interpretations
« Reply #16 on: January 02, 2018, 05:25:18 PM »

In Stunt & Scale the overline length limit, 70' true, is the only rule that matters.

(Clip)


Just to clarify, the maximum line length for CL Precision Aerobatics and CL scale is 70 feet, measured from the centerline of the model to the center of the handle.

Keith

Offline bill bischoff

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Re: Control Line Length Rules/Interpretations
« Reply #17 on: January 04, 2018, 10:43:41 AM »
In no instance relating to the rules does the actual length of the line (eyelet to eyelet) factor into the measurement. It is always measured from the center of the airplane to the grip of the handle. In stunt, where line length is one of many trimming variables, it is convenient to discuss the actual length of the lines when comparing one set to another. This is a separate consideration from the rule book minimums and maximums. I'm sorry if this is repetitious, but I'm not certain these points were completely clear.


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