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Building Tips and technical articles. => 1/2 A building. => Topic started by: Ward Van Duzer on July 20, 2008, 02:44:04 PM
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Ok, just starting to fool around with some of this 1/2 A stuff! (Lots of questions). I'm using 8 lb Spider-wire for lines on a TeeDee powered stunter. This OK? Yes I'm CA'ing the knots! But what is appropriate length? Flew this AM with about 37+ feet and that seemed a little long...Using Cox grey 6 X 3 prop. OK? D--n broke one! Not too many left...Anything better out there? Would switch to a Bolly F/G if need be. My 15-20 year old Cox Competition fuel still seems to work. (Have about 3 pints left). What formulas are you guys using?
BTW, Had a ball! HH%%
Ward
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I usually fly .049-powered planes on 35' lines, up to 42' if I want slower lap times. 8-lb Spiderwire is sufficient; I have used 12#, depending on what is available when I go to buy a reel. Can't tell much (if any) difference in performance. My .061-powered models use 42' minimum line length, up to 52', again depending on the lap time I want. You have to be kinda masochistic to put an .061 on 35' lines, although I do it occasionally (too lazy to roll out another set of lines for maybe one flight).
You don't need to CA the knots if you use a Palomar knot, or two or three other kinds that are non-slip types. A standard double hard knot (square knot) will not hold in Spiderwire; it will slip out. (Unless CA'd I suppose!)
I don't have a TeeDee .049 so can't speak to the appropriate prop, but a 6x3 seems a little much, I would run that on an .061. My .049s (Norvel, VA, Black Widow, Brodak) mostly use 5" or smaller props, down to 4 1/4", x3" pitch. Whatever it takes to get the rpms up, the little engines don't lug well. The Cox black plastic 5x3 broad-blade prop is sort of my base, then I whittle down the diameter from there as needed. APC props perform better but will break, and will do more damage if you get a finger in one! I've found the APC 6x2 to be just about the ideal prop for an .061-powered stunter. APC makes a 5.5x2 that might work well on a good .049 for stunt.
Fuel, I've used everything from 10% to 35% nitro, castor oil and synthetic, it all seems to work pretty well--the higher nitro does I think result in easier starts. I don't habitually tach my engine runs, but I don't notice any real difference "by ear" in the various nitro levels.
You got pics of what you're flying?
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Ray,
I have a roll of 8# size (12# strength) Spiderwire as well, but haven't figured out how to hang a line clip on a Palomar knot? HB~>
The illustration shows the drop loop of a Palomar knot going through a fish hook eyelet, and then around the shank of the hook, before being pulled tight.
I've read here that using a too tight radius in the Spectra line termination can reduce the pull test to half the lines rated strength, and that seems a bit risky.
How do you connect your lines to a half A line clip?
Bill
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OK, here's what I'm flying! Not real hi-tek. Actually a Red Reinhardt design from the 50's. He called it the Snapper, a design in "Variable Dihedral"! Yup, the 1/8th sheet wing flexes considerably in manuvers. I re-published this in FM 12/89 as a take apart. Plans may still be available.
As to what kind of knot am I using...Yes, I am a fisherman but that spider web stuff is so fine I do it the simple way. An overhand loop. Now you know why I use the CA!
W. :P
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I have had good success with MAS 6 x 3 cut down to 5 1/2 on TD's. The APC 5.75 x 3 also works well. Usually used 42 ft 008 cables.
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I was not ready to post my latest information on 1/4A flying lines but!!!
I have not finished a series of tests on different weight lines but at present I can state that if you use any knot directly on the line clip it will fail at about 50% of the rated line test. I.E. 20 lb test line will break at about 10 lbs load.
BUT!!! If you tie the line around a ferrule, like you use on bigger steel lines, with a palomar knot it will hold to almost the rated breaking strength of the line.
I will add a sketch soon.
Also do not use monofilament line!!! Use only woven, non-stretch, line. Ask me how I know!
Clancy
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How about a source on those ferrules!
I used to do it the cheap way once upon a time. You know the little brass eyelet that was on the hanging items like Perfect and others? I would save these for my larger planes just for this purpose. Never had to buy any!
Robert
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Ward,
Thanks for the info. I have lots of CA! ;D
Clancy,
Looking forward to your article. H^^
Your earlier postings were the source of the line failures I cited.
Bill
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How about a source on those ferrules!
The best, IMO, is P/N 3436T12 on page 1390 of the McMaster-Carr online catalog. Not cheap (≈ 25¢ ea. if you order 50) but almost infinitely reusable, and good for any size controllines or leadouts.
Ralph
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Ralph,
Those look good, and the price is reasonable enough, but have you tried them?
If so, how sharp are the small open end edges, where the line would rub?
Bill