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Building Tips and technical articles. => ARF'S => Topic started by: Larry Renger on June 04, 2007, 07:05:04 PM
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I completed the Smoothie today, and checked the balance. It is at 3-1/4" back from the LE. The book says 2-1/2". What have actual flight trimmed models ended up? ???
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No further back than the spars, maybe a little further forward for first flights. Another is to hold it by the leadouts and see if it hangs nose down a little bit. DOC Holliday
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Larry,
Mine is right at the 2.5" point and seems to fly fine. I put it together for OTS at VSC and have not yet had any of the local experts check the trim. My engine is a Thunder Tiger 36 which weighs just over 8 oz bare. I started with a tongue muffler, but switched to a conventional when the CG came out a little aft. The airplane seems very responsive with the CG where it is, so I wouldn't think moving it aft very much would be a good idea. Got a heavy spinner around somewhere?
Steve
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Actually, what I did was put the stock Brodak muffler back on instead of the lightweight Hyflo. That put the CG right on the money. Eventually I may cut lightening holes in the aft fuselage and rudder and put the Hyflo on to save about 2 ounces. Currently the plane weighs exactly 42 ounces.
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Looks good Larry, nice pilot. VD~ VD~ VD~
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I put up one flight today. The plane looks like it will trim out in a real hurry. I need to tame the Brodak 40 though. I can't get a good needle setting with the 15% fuel I had along. I expect 5 - 10% is more like it, at least until I can get an extra head gasket or two.
I didn't notice any hingeing in hard corners, so I guess the fixed tab is about right.
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I have had my Smoothie for over 1 year and enjoying it very much with Fox35. Only issues were LG had to be re installed- after a few grass landings.
Second issue has been the covering is gradually failing- it is lifting up on the wing- and some trim is peeling off.
Anyone have hints on how to re attach the covering-i.e can I use Balserite and then re heat seal? I tried to use cyano and it doesn't adhere to plastic? Will epoxy finishing resin work?
If no good short term solution- Will I will have to strip and recover completely?
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Have you tryed the T/F trim solvent ?
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I've been doing this on my arf's for over a year now. I clean the covering with rubbing alcohol first. This includes the underside of the peeling portion as well. I wouldn't use Balsarite. A club member who used Balsarite ended up with a big mess. Balsarite has strong solvents just like dope in it. I'm sure if used very sparingly, it would do fine but It may take the color off of the covering during the ironing process. I've been using a product called Balsaloc. This is a water based product in my opinion its like Elmer's glue. I've had great success with this. Its water based so clean up is simple and it dries with very little residue.I've been meaning out of curiousity just to try Elmer's. It smells just like it. I apply it very thinly with a small artist brush and let it dry clear. The coverings used on the arf's seem to iron down better using lower heat temps. I use just enough heat in the repaired area to get it to stick down. I've had zero lifting problems in the repaired areas. I had some curling with the pressure sensitive decals as well, this stuff glued it right back down. The majority of my lifting problems occured where one color is laminated over another. This is always a problem especially when the seam is to the wind. This stuff works great. Good Luck, Ken
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I flew the Smootharf again today, and the plane is really a charmer. I still have some trim issues, but the engine is the main problem. The engine vibrated loose, I mean like the screws backing off 1/8"! I got that tightened up, and then the needle started backing out. I tried to tighten the needle collet and the whole needle assembly is rotating. AAAARGH. I will deal with this this week.
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Hey Larry and other Smoothie guys,
Did you hook up the flap and elevator pushrods into the suggested holes in the horns? Does the sugggested hook up give the right amount of flap and elevator movment?
Thanks,
Jim
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My SmoothARF is hooked up as per standard practice, center BC hole for flap pushrod, flap pushrod to top hole of flap horn, elevator pushrod from center hole to center hole, resulting in about equal degrees of defection on flaps and elevators. I have the luxury of being able to experiment as I built it as a fully take-apart model. Tried the elevator horn hole farthest from the pivot but this produced more flap than elevator deflection. I will post some photos if I can get them to load.
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I did not use the recommended hookup. I have the B/C rod going from the center hole to the 2nd hole in the flap horn. The elevator rod goes from the top hole in the flap horn to the 2nd hole in the elevator giving me about 3/2 elevator to flap movement. I am extremely pleased with this setup, it turns on a dime, but does not hunt.
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My control hook-up is the same as Larry's. The airplane flys really well like this and turns very tight when needed.
Steve
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Local Combat Ace, Jeffery Rein, has been campaigning an ARF Smoothie in OTS, Classic, Intermediate and now Advanced. It's powered by one of his old Magnum XL .36 (round cylinder) SLC engines, same venturi, same compression, different glowplug, different prop. We got him to open the venturi up from .250" to .265", and change from an 11-4 APC to a 10.5 x 4.5 APC fairly recently, so lookout! Stock muffler, OBTW, + metal uniflow tank.
Regarding the venturi size...it was either that, or shorter lines, as it sagged a bit overhead. A filter or layers of pantyhose will return the effective venturi size, if this is too large. It's looking better, tho the covering is starting to slide off onto the pasture like a hot cow pie. The Smoothie is a good flying model, if you get it all tweeked up right! LL~ Steve