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General control line discussion => Open Forum => Topic started by: Dan Miles on November 29, 2006, 02:57:49 PM
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anyone out there know how to calculate drag on lines. I would like to know how much the lines drag but don't know how to figure it.
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Dan,
Follow this link http://www.go-cl.se/cl.html and go down to the Team Racing section.
Look under "As I F2C it" for the team racing spreadsheet. Its a downloadable xls spreadsheet you can manipulate to get the results you want.
Scott
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Go to the download section of this forum and download LineIII, it includes a couple of PDF files that will tell you more than you ever wanted to know about line drag.
It isn't a simple calculation as too many things effect it.
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Dan,
You are not planning on getting technical on the group are you? The simple answer is that there is enough drag from the lines to make the airplane rotate 360° each lap...... n~
John
Good luck on your quest.
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I've been busy and didn't have time to get back till now sorry Here's what I'm getting to; We know that the plane should fly with it's front to back centerline 90 degrees to an imaginary line between the handle and the plane so it will turn loops without yawing around (speed planes can piont "in" a little and get a little more speed but they don't loop). All I'm saying is that the center of drag (including the lines) and the center of thrust should be the same or the plane will try to fly toward the drag. If the those centers were on the same line without lines then we need to add the amount of the lie drag on the outboard side. Bandaids can be used like engine offset, rudder offset, linerake and some others but they will cause other problems when the conditions change like a manuver, going into and outof the wind, going slower at the top of a wingover. So eventhough these bandaids seem to slove the problem under certain stiuations, it will not work throughout. If we can get the drag (including lines) and the thrust on the same line we will know that the problem is somewhere else. If your plane flies at you, points away from you or yaws around in manuvers, (like changing from inside to outside in an 8) you will know the planes (inculing the lines) aerodynamics is right i that respect.
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Sounds interesting, this would mean the engine needs to be someplace on the inboard wing in order for the center of thrust and center of drag to be in the same location. All you effectively would be doing is lengthening the outboard wing. Not sure if it's ever been tried, would take a ton of tip weight.
Every aspect of a stunt ships is a compromise of some fashion. If you make one aspect perfect something else could be off so far the model could very well be unflyable.
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Longer OB wing to make the thrust get in line with the drag.... Ok, now how would we compensate for the lift differential. There are many forces to think about here. I suppose the additional drag of the longer OB wing would require that the engine be brought closer to the center again...
John
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the outboard drag could be a fence like was on the Goldburg Wizzard ??. or some other way to get the thrust/darg (including lines) at the same place
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Longer OB wing to make the thrust get in line with the drag.... Ok, now how would we compensate for the lift differential. There are many forces to think about here. I suppose the additional drag of the longer OB wing would require that the engine be brought closer to the center again...
John
Hi John,
I don't know about how to get the thrust line/drag evened up, but I do know of a famous or rather infamous design that has a longer outboard panel. y1
Maybe the designer(he's a member) will pontificate ion that subject.
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If anyone remembers Dave Trible's Shameless design will have noticed that the outboard wing was longer. Of course it is a profile design. Daves theory was this was centering the the weight of fuse, engine and associated stuff on the center of the wing. I had mine out yesterday just to get a flight up. Keep forgetting what a terrific flying design it is. DOC Holliday