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Author Topic: Line size for 15 Profile Carrier  (Read 4667 times)

Offline Paul Smith

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Line size for 15 Profile Carrier
« on: June 07, 2014, 10:25:26 AM »
According AMA CL General rules the line size in special non Rule Book events needs to be no less safe than similar Rule Book events.

Class II Carrier: three .018" lines (frontal area .054") or two .024" lines (frontal area .048").

Class I and Profile: three .015" lines (frontal area .045") or two .020" lines (frontal area .040").

As you can see, when you go from three lines down to two you must step up not just one, but two lines sizes.  I'm dabbling with a 2.4 Profile plane and I was a bit shocked that I needed .021" lines. I had assumed the hit would only be .018".  But realistically, .018" would have cut the frontal area down to only .036" thereby giving 2.4 a HUGE advantage over three line mechanical.

The Rule Book says .020" stranded, but there's no such product so the rule is effectively .021" stranded: .042" of frontal area.

In 15 Profile Carrier three .012" lines equal .036" of frontal area.  Two .018" lines also equal .036" of frontal area.  Fair is fair and safe is safe.  A 15 on .018" line?  Overkill maybe?  But flying my Profile on .021" is overkill too and that's the rule.


Paul Smith

Offline Trostle

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Re: Line size for 15 Profile Carrier
« Reply #1 on: June 07, 2014, 12:30:35 PM »
Well, I am not familiar with whatever the "rules" are for .15 Carrier, whether "unofficial" or "official" or whatever.  However, if anyone competing in this event following whatever those "unofficial" rules are, what difference does it make what the line sizes are?

As the famous once Secretary of State proclaimed "WHAT DIFFERENCE DOES IT MAKE?"

Yes, if the rules are to be interpreted as Paul suggests above, those line sizes seem a bit exaggerated, but if everybody is following those rule, then no one is being unfairly penalized.

Keith

Offline Paul Smith

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Re: Line size for 15 Profile Carrier
« Reply #2 on: June 08, 2014, 07:25:43 AM »
My point is that in unofficial non Rule Book events the safety rules need to be "no less safe" than rule book events.

When the 15 Profile Carrier rules were locally developed, they simply said .012" lines with the assumption that everybody uses three lines.  Now, with 2.4 engine control easily available, some competitors will be switching to two lines.  In the absence of legislation, they will fly with two .012" lines, thereby gaining overwhelming advantage in both high and low speed.

As Mr. Trostle is well aware, stunt flyers strive to use the thinnest lines that can get away with so as to maximize performance.  The same is true in carrier and most other events.  So it's up to the elders of the sport to define what the minimum line size is. 

I modified a 36 Profile Carrier model to 2.4 and was forced to change from three .015" lines to two .021" lines.  A couple of test flights verified that the upgrade in line size is fair and reasonable.

I just want to start the discussion on 15 Carrier planes with two lines.  In the absence of action I will just build one and fly it on .012" lines until the rule change comes.


Paul Smith

Offline Wayne J. Buran

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Re: Line size for 15 Profile Carrier
« Reply #3 on: June 08, 2014, 09:49:47 AM »
Good points Paul.
Wayne
Wayne Buran
Medina, Ohio
AMA 14986 CD
USAF Veteran 35 TAC GP/ 6236 CSG, DonMuang RTAFB, Bangkok, Thailand 65-66 North Coast Controliners   "A fine is a tax for doing wrong. A tax is a fine for doing well!

Joe Just

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Re: Line size for 15 Profile Carrier
« Reply #4 on: June 08, 2014, 10:28:22 AM »
Paul, good catch. Now, if we had required scale points in .15 I believe it would been a good idea. Perhaps the NCS and management could enact a .012x2 line ruling.

Offline eric david conley

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Re: Line size for 15 Profile Carrier
« Reply #5 on: June 08, 2014, 11:53:22 AM »
     I can give you a little history on line size for 15 carrier although it is my perceived history and might not line up with the facts as others see it. The NCS works pretty hard to keep the rules for the AMA events as clear as possible and still seems to generate a lot of heat for one reason or another. So to expect them to make rules for all of the current carrier events and then try to enforce them all across the Nation is a bit of a stretch I think. Except for Nostalgia events which are flown basically under the old AMA rules (back in the day) 15 carrier, Skyray 35, North West Sport 40, and several other events were local events with not much thought to whether they would go Nation or not.
     As the rule for 15 carrier states (which rule) line size will be .012, so I would think that that is the size of line to be used in 15 carrier. If I'm reading the line strength's right in the CL General Rules .012 line are good for around 40 pounds of pull which is certainly adequate for a 2 or 3 line plane that has a pull test of 25 pounds. So what is the big question? My best guess is, do you want to p-s off your fellow competitors or?  When I built my first electric 15 plane in 2012 I got into a conversation with Dick Perry the NCS president about line size for the plane. 2-.012s being my choice but thinking about the other competetors and thinking I better go to 2- .015s so I wouldn't get run out of town. I asked the question, Dick looked at me and smiled and said to the effect "thank goodness I don't have to make that choice because the NCS didn't write the rules for 15 carrier but in the entrusts of keeping the Peace you probably better go with the .015s" not a direct quote but words to that effect.
     Sooo, if I were Paul (ho,ho) I would go for the 2-.012s which are what the rules call for and are plenty strong for the task so that old Eric depending on the heat you take could maybe switch back to the .012s.
Eric

Offline Paul Smith

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Re: Line size for 15 Profile Carrier
« Reply #6 on: June 08, 2014, 04:11:14 PM »
We used to use .012" in FAI combat, but they broke just test-flying without a midair.
The sane guys went to .015" even before the rules change.
Some of us used .018' just to avoid lost airplanes.

In 15 Carrier: 

2 x .018" = a safe and level playing field.
2 x .015" = a reasonably safe event with a strong advantage for two lines vs three.
2 x .012" = a totally overwhelming advantage over three lines in both high & low speed and highly questionable safety.

As I said before, I'm planning to build a 2.4 15 Carrier plane soon.  In the absence of a ruling to the contrary, I will accept the advantage of 2 x .012" while it lasts.  Fair warning.




Paul Smith

Offline Mike Anderson

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Re: Line size for 15 Profile Carrier
« Reply #7 on: June 08, 2014, 05:11:50 PM »
We kicked this around a little this weekend at our Midwest CarrierFest - and reached about the same conclusion.  That moving up two line sizes (from .012 to .018) would keep the drag about equal, as was done in the AMA events and would be more than adequate safety-wise.

I suppose that NCS should probably incorporate some changes so that there is equality in the Top 20 posting or in the unofficial Nats events.  Otherwise, at the local level if some areas want to just go with .015's, I seriously doubt there would be much impact on scores, given the 70 mph speed limit.

Mike@   AMA 10086
Central Iowa

Offline eric david conley

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Re: Line size for 15 Profile Carrier
« Reply #8 on: June 09, 2014, 01:58:02 PM »
     We have to be very careful when trying to "equalize" line drag when talking about 2-lines verses 3-lines. When I went from 3-.012 lines to 2-.015 lines I didn't feel any difference in the HS portion of the flight. I felt the difference in the LS portion of the flight. It was more difficult to keep the plane out on the end of the lines and the sag was much more apparent. I have experienced the same thing when I went from 3-.015 to 2-.021 and also going from 3-.018 to 2-.024.
     When I look at the difference in the AMA carrier rule that cover line size for 2 or 3 line systems the 2 wire systems have an advantage as far as combined diameters. The AMA rule has to cover the breaking strength of the two systems and is there so that we all can pull those terrible pull test figures with out the lines breaking (never mind your poor airplane). I don't think the AMA was looking at line diameters at all, it was "is this going to be strong enough to be used in the pull test". Having said that, the pull test for .15 carrier is 25 pounds.
     Another thing I noticed when going from the 3 line to the 2 line was I filled up the reals to a much greater extent with the larger line size lines and they were much heavier.
Eric

Offline Paul Smith

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Re: Line size for 15 Profile Carrier
« Reply #9 on: June 09, 2014, 06:22:22 PM »
In consideration of the 70 MPH speed limit, line drag is still a huge key issue.   With less line drag it is possible to hit 70 MPH and set up for a MUCH lower low with smaller lines. 

I am sure I can do 70 MPH with .012", .015", or .018" lines.  But the thinner lines will allow a MUCH lower low speed. 

So the question is simply this:
Do we want to let three-line and two-line systems compete as equals, or do we want to skew it so three lines are rendered obsolete?

The Rule Book events have done a decent job addressing this.  I hope the non-Rule Book events follow suit.
Paul Smith

Offline Robert Frogner

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Re: Line size for 15 Profile Carrier
« Reply #10 on: August 23, 2015, 10:29:04 PM »
So I see a lot of discussion here but no conclusion.

What is the rule for 2 line 15 carrier competion?

Is 2 line 15 carrier  required to have .015 dia lines? Or something different?

What was requiered at this years Nats unofficial event for 15 carrier?

Thanks for any updates.

Offline eric david conley

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Re: Line size for 15 Profile Carrier
« Reply #11 on: August 24, 2015, 09:53:06 AM »
     Hello Bob, it is nice to see you asking questions about 15 or for that matter anything else. I've missed seeing you at the Carrier Plus contests in Phoenix. On the control line question it is .015s for 2 wire and .012s for 3 wire. A lot of talk about it, and it was decided to up the size to try to equal the drag thing and was not because 2 .012s wouldn't have worked OK. Are you flying at the contests in Oakland? I'm having very good luck with the e-15 although Burt can beat me if things (weather) are equal, he is flying a Nelson 15 with I think combat wing from a FAI type combat ship. So nice to see your name. Eric
Eric

Offline Mike Anderson

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Re: Line size for 15 Profile Carrier
« Reply #12 on: August 24, 2015, 10:09:04 AM »
Welcome back, Bob.  This was discussed at the NCS meeting at the NATS.  As Eric mentions, the decision was to go to .015 x 2 in .15 Carrier. Th ere was some discussion of whether we needed to go to .018 x 2 (to equalize the cross-sectional area with .012 x 3) but the general consensus was that the difference is negligible.
Mike@   AMA 10086
Central Iowa

Offline Robert Frogner

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Re: Line size for 15 Profile Carrier
« Reply #13 on: August 24, 2015, 11:17:28 AM »
Eric and Mike,

Thanks for the quick reply. I have been out of flying for a while now, somewhat due to my medical issues, but have regained interest lately. Haven't flow anything for probably 3 or 4 years. However I have been thinking about the 2.4 Ghz setups and thought it would be good to try. I have some basic stuff, transmitter and batteries, coming from HobbyKing and found a good replacement motor for my old and well used Sniper. I had converted the Sniper to electric a long time ago (I think it was 2007 or so) and thought that I could bring it up to modern standards by installing the 2.4 throttle control. I am hoping to have it flying in the next month or so with an eye on getting to Phoenix again this year in Oct. Hopefully it all comes together and I can make the trip.


Offline eric david conley

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Re: Line size for 15 Profile Carrier
« Reply #14 on: August 24, 2015, 11:29:07 AM »
     I guess I should have gone back and read the whole Topic on this subject before I jumped in with my comment. After I went back and reread what Paul and Mike said I think I got a little ahead of myself. I do remember the discussion (sort of) on the subject and Dick Perry said the NCS did not write the rules on 15 carrier and therefore couldn't change them. So I'm thinking ---------------------------------------hummm? Sorry Bob, might as well forget what I said above other than it was nice to know that your still thinking about the carrier planes. It was you that got me thinking about the electric 15 thing. Eric
    
Eric

Offline Paul Smith

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Re: Line size for 15 Profile Carrier
« Reply #15 on: August 24, 2015, 03:51:42 PM »
If nobody wants to change the rule, it's OK with me.

The rule says ".012" lines.  So you can fly with TWO .012" lines if you want.

I have stepped into the new millennium and gone to 2.4.  So flying on two .012's is OK with me until somebody changes the rule.
Paul Smith

Offline Mike Anderson

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Re: Line size for 15 Profile Carrier
« Reply #16 on: August 25, 2015, 01:52:30 PM »
I just heard back from Dick Perry, regarding the line sizes for .15 and the discussion at the NCS membership meeting.  It was voted to make it 2 x .015's for 2 line setups.  That does not make it an 'official' NCS rule change until voted on by the NCS membership, which has not yet been done.
Mike@   AMA 10086
Central Iowa

Offline john vlna

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Re: Line size for 15 Profile Carrier
« Reply #17 on: August 26, 2015, 11:19:07 AM »
At the Brodak FlyIn when we started allowing electric powered models we modified the line rule for 15’s. At that time 2.4Ghz was not legal so to have a two line electric throttle or electric motor insulated lines were needed. Commercial nylon coated lines were typically used although you could make your own and indeed that is what I did. The commercial lines were close to .015(not including the nylon insulation), but most measured at .0147 or so. With the help of Everett Shoemaker we did some stress analysis and determined that .014 was safe. Of course you can’t buy .014 stranded, they are .015, but the nylon insulated lines would then be legal.

To date, and we only have one more year, I am the only one to fly electric 15 at Brodak’s. I use .015 insulated lines. I don’t need the insulation today, but they are left over from before 2.4GHz was legalized. They were insulated by me so they aren’t as draggy as nylon lines.

These are also the lines I use at Muncie. Some day I’ll make new ones.

Here is the rule statement from the FlyIn web site.

All AMA Safety and general CL rules observed. Please note line lengths are specified differently than most other AMA events. Scale and AMA/Sportsman are 60ft. to 60 ft. 6 in. Not 60 ft. plus or minus 6 in. Similarly 15 profile is 52 ft. to 52 ft. 6 in. All are measured from the aircraft centerline to the handle grip center. (Where your palm rest on the handle.) Lines diameters (for three line systems) are .012 for 15, .015 for AMA/Sportsman and Class I, .018 for Class II.  For 2 line systems line diameters are .014 for 15 Profile, and per AMA rules for AMA/Sportsman and Class I & II.


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