dkshema
rrProfessor
Location: Cedar Rapids, IA
| That's not exactly true about not having to modify the tail case to clear the plastic ball link if you use the Z-bend up front.
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I have a C5 and its tail case is the older version that is straight off the Caliber 30. None of my three Caliber 30's OR my C5 had a clearance problem between the tail case and the plastic ball link at the rear.
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The tail rotor case on the Caliber 4 is a new version, one that showed up after the initial Caliber 5 kits were shipped.
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The early C5 kits were shipped with the same tail rotor cases that were used on the Caliber 30. There were quite a few reports of nearly instantaneous failures of the TR case on some of those early C5s. The actual cause was due to running longer, heavier TR blades on the C5 than were run on the Caliber 30. People didn't bother to balance the TR assembly out of the box. The added mass of the C5 tail rotor system, when unbalanced, pushed the TR case to the failure limit. Vibration fatigued the plastic at the transition joint between the TR tube and the rear half of the case that holds the TR shaft and bearings.
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Although balancing the TR system would have cured this problem and allowed the original Caliber 30 cases to be used (my original C5 has gone through its second season without a hint of TR case failure, and it has the original Caliber 30 style cases), Kyosho chose to modify the tail rotor case by adding two horizontal ribs on each side of the tail case.
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They started shipping those with the later C5 kits, and in the Caliber 4 kits.
When I built my C4 this fall, I found that the placement of the lower rib on the left side of the TR case limits the full throw of the TR pitch slider lever because the plastic ball link runs into the rib as it moves to full forward throw. The Z-bend has nothing to do with the geometry back there, because of the two pushrod guides that are installed between the Z-bend and the rear-end ball link. You can move the Z-bend end wherever you want, you won't affect the clearance at the rear of the pushrod because that clearance is determined by the placement of the rearmost pushrod guide. That guide sets the distance between the boom (and tail rotor case) and the pushrod. Moving the Z-bend can't change this distance with the guides in place.
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Earlier this year, I set up a fellow's C5 (which had the "new" TR case). I had binding problems at the TR case, and found the same problem -- the plastic ball link runs into the lower rib on the left side of the TR case. I had to modify the case to make clearance for the link to allow full rudder travel without binding.
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Yes, the Z keeps the rod from rotating, so that the plastic ball link always stays in the same relative position, no matter what the heli does. Unfortunately, the steel ball is mounted vertically on the bottom side of the pitch slider bellcrank, and the plastic link snaps onto it so that it is horizontal, (parallel to the bottom of the skids. In this position, the plastic link interferes with the lower rib on the TR case.
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I've not had any trouble with the Z-bends, my many year-old Caliber 30's attest to that. And yes, the servo arm hole does get bigger with time. I've just lived with that until recently.
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Of late, I've contemplated just whacking off the Z-bend, and using a 2mm die to thread the end, add a ball link, and do away with the Z completely. I haven't done it, only contemplated it, as I'd have to order a die to do the job. (LHS sucks here in Cedar Rapids).
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I don't believe the pull-pull system adds any friction, it's actually a much better design (a vertical shaft supported by two ball bearings), is more precise, is used on the flagship Caliber 90 kits, and recently found its way into the small 450V electric from Kyosho.
It's one of those "nice" stock design features that comes at little added cost overall, and sets the new Caliber designs apart from the rest of the world.
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Still, it would be nice to see more effort go into fielding an affordable "60/90" heli, than guilding the lily by cranking out endless variants of the 50-sized heli.
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* Making the World a Better Place -- One Helicopter at a time! *
Dave |
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