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General control line discussion => Open Forum => Topic started by: Dwayne Donnelly on January 14, 2023, 06:32:45 AM
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The plans show the leadouts well behind the CG and I'm wondering if this is because of the I-Beam being in the way or is there something more to it? Was it a 50's thing to get more line tension with a Fox 35? Swept forward TE? Would it hurt if I moved the leadouts forward? This inquiring mind would like to know. ;D
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Dwayne,
The simple answer is to use an adjustable leadout slider. I would run Line III app to get a starting point for the center of the leadout position and adjust from there. You will likely get a number around 5/8" behind the CG. Hanging the ship from the leadouts is another way to get a starting position, nose should hang down a few degrees. One indication that the leadouts are too far back the ship hunts a little in a light breeze (usually cured by moving them forward 1/8" at a time). Are you using cable or solid leadouts? If solids drill out the slider holes to 3/32" to avoid binding.
Best, DennisT
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The location was pretty common for the time period AND the Fox. Rudder offset as well. I built a number of these years ago and a couple very similar recently and would suggest you keep it as shown but perhaps make them adjustable at least in small increments close to the shown position. You aren't going to have a piped .40 or .61 in the nose pulling the lines arrow straight from the handle. The norm for these airplanes will yield a wide bow in the lines from the handle to the airplane (but good line tension, properly set up). This will create a major trim issue if the lead out position is further forward. I'm not sure any mathematical formula will consider drag induced bow in the flying lines-at least to this extent.
Dave
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Thanks I should of added I'm using a Premier gray case Merco 40 so there will be more power than a fox 35, and using cable leadouts. Not sure how I would add adjustable leadouts with an I-beam, I watched Windy's I-beam Spitfire videos and it did not have adjustable leadouts but he did say he'd like to install one.
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One thing that is different now then back in the day is the pull test is based on model weight not engine size. For this ship you would have needed to fly on 0.015" cable. Since this ship should come in around 40 oz. ish you could use 0.012" cable and reduce the line drag and needed tip weight. The "Line III" app does take into account the line diameter, length and expected speed (should be a lap time around 4.8 sec on 60' C to C). Do search on this forum for Line III to get the app,
Best, DennisT
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One thing that is different now then back in the day is the pull test is based on model weight not engine size. For this ship you would have needed to fly on 0.015" cable. Since this ship should come in around 40 oz. ish you could use 0.012" cable and reduce the line drag and needed tip weight. The "Line III" app does take into account the line diameter, length and expected speed (should be a lap time around 4.8 sec on 60' C to C). Do search on this forum for Line III to get the app,
Best, DennisT
Hi Dennis the Line III download says "Resource has been removed"
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Dwayne,
Do the search of LineIII (no space). One source to look at is: http://www.tulsacl.com/Linelll.html
Best, Dennist
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Thanks I should of added I'm using a Premier gray case Merco 40 so there will be more power than a fox 35, and using cable leadouts. Not sure how I would add adjustable leadouts with an I-beam, I watched Windy's I-beam Spitfire videos and it did not have adjustable leadouts but he did say he'd like to install one.
Look at reply #37 in:
https://stunthanger.com/smf/gettin-all-amp'ed-up!/starting-to-build-a-59-ares-brodak-kit/
This is how I added an adjustable lead out. Haven't flown it yet so I don't have any adjustment data yet. I usually hang my airplanes from the lead outs and adjust for a 3 deeg noise down starting point.
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I made an adjustable lead out guide on my Argus using a maple motor mount, holes drilled for the eyelets, and a slot in between. Only difference is that i used solid lead outs, which should be fine for flexible lead outs too.
Kevin