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Building Tips and technical articles. => ARF'S => Topic started by: Tom Schwartz on August 25, 2011, 08:43:01 PM
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I just put together an Oriental ARF and powered it with a Fox 40. Although it flys wonderful and is rock steady, I am of the opinion that the control throw is very long and requires excessive wrist movement to get full control movement. The handle I am using has a 4.25" line spacing. Is this normal? ??? I used the center hole on the bellcrank as suggested in the plans.
Thanks,
Tom in NEPA
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Is it nose heavy? The Oriental ARF I built had a Brodak .40 with a tongue muffler. This is a fairly light set up. Even with this combo it was borderline nose heavy. The Fox weighs a LOT more! First thing I would do is check the CG.
Chris
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CG is good. The plane does respond well to inputs, It just seems to take lots of wrist movement to go from full up to full down.
Thanks
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So I measured the throw on my PT19 and my sons P40 since they are the only planes I have to compare against. The PT19 measures 1.5 inches from lead out up end to lead out down end at full throw. The P40 measures 2.0 inches. The Oriental measured 4.0 inches, so that is what I'm trying to describe. Maybe this is normal, but it's like going from a Ferrari to a station wagon in control. The difference caught me by surprise.
Thanks
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It sounds like you could use a wider line spacing on your handle. When I set up the line spacing on a handle my initial setting is the spacing that will move the controls their full travel with the airplane sitting on the ground. With the way I move my hand an airplane with a 4" bellcrank the spacing ends up at about 4 1/4, with the down line spacing more than the up line. If you know you are getting full mechanical throw and the plane still feels mushy, try some tailweight. That is what I did on my last plane. I keep a dedicated handle for the main stunt plane I fly, because a lot of the trimming is done on the handle end.
Mike Greb
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Remember that the plans/instructions will show the CG to be at a location that is "safe" for fliers of dubious skill levels. Since you are an excellent pilot, you will probably want to shift the CG aft to suit your taste. Remember that shifting the CG will also indicate a shift in the leadout position. LO's should be about 3/4"-1" behind the CG. Leadout position will affect the stability of the model also, so keep that in mind. y1 Steve
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I built both the kit and the arf. I found out early on prior to buying the arf that guys were flying the arf with the large 5" hot rock. I couldn't figure out why until I purchased the arf. The arf has a 4" bellcrank while the kit has a 3". I personally don't like the 4" bellcrank. The other point is the Oriental arf and also the kit was designed around the Fox.35. The Fox.40 is heavier which has you in a nose heavy condition. I built my arf with a LA.40 which was almost 3oz's. heavier than the Fox.35. I almost planted the plane on the first flight. The plane went into the inside fairly well but I barely had enough wrist action to recover. Although the larger bellcrank makes the movements more precise I wish I knew what I knew now. I certainly would've moved the pushrod to the inner hole. I ended up building a weight box into the tail which also allows me to adjust the clevis I installed. I started with 3oz's in the tail but I now fly with 2.75. Maybe a wood prop on the nose especially if your using a spinner to help lighten things up. Ken
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Remember that the plans/instructions will show the CG to be at a location that is "safe" for fliers of dubious skill levels. Since you are an excellent pilot, you will probably want to shift the CG aft to suit your taste. Remember that shifting the CG will also indicate a shift in the leadout position. LO's should be about 3/4"-1" behind the CG. Leadout position will affect the stability of the model also, so keep that in mind. y1 Steve
LOL, Only in my dreams! n~