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Here’s the cyclic mod I posted on the ROG a while ago. The standard nylon bearing set-up is pretty naff and fundamentally flawed in principle. Changing to ball bearings seemed the way to go. I purchased some pretty good quality shielded bearings that are, coincidentally, exactly the same thickness as the nylon bushes supplied by RW (.026 in). Diameter and bore are again, the same. They are Japanese bearings and have the number IJK9R48 on them but I reckon they’re a universal standard size. I machined the welded steel bushes in the cyclic cross tube to 1.275 inches overall length. Thin stainless steel washers (0.026 in thick) between the fender washers and the bearings resulted in satisfactory clearance on the cyclic clevis. I expect that all clevis castings are slightly different so the above dimensions could change slightly from ship to ship.
Apparently, Rotorway once used bearings on this assembly but changed the design to the naff nylon bushes - probably to save costs.
I drilled all the foot pedal holes on my universal mill, keeping everything square with a simple spirit level and toolmakers square. The idea is for the holes to all be identically square and central to the tubes so that the parts can be interchanged if need be.
Not much to report on the collective and throttle control. I decided to have the main components chromed. This of course means assembly then disassembly - a very familiar concept to any Rotorway builder. Removing the nylon pivot bushed from the blind tubes necessitated a tool.
I folded this simple removal tool from a piece of 1/8 inch x 3/8 in stainless strip
Pretty obvious how it works. Grip the tool in a vice and tap off the tube.
Here I’m polishing in preparation for the Chrome plate. Most chrome platers will do this as part of the job but we’ve got the equipment so it saves a little money to do this part ourselves.
One little thing that niggled me slightly was the split tube peg drive on the removable passengers collective throttle rod. The standard installation leaves one roll pin right on the end of the split in the drive sleeve. I worried a little if the throttle ever became tight for whatever reason the sleeve may split
I made a counterbored replacement washer into which the end of the sleeve locates This will prevent the split tube from the possibility of opening up and splitting.
Makes sense to me but I’ll check it out with my CAA inspector.
Here’s the Chrome batch fresh from the platers.
Collective and throttle assembly fitted to the ship
Cyclic and cables all in place and adjusted
THROTTLE ‘B’ ARM UPDATE
Rotorway have issued an update Kit to correct a possible problem on Exec throttle linkages. It appears that you can find the engine revs increasing when you raise the collective to flare at the bottom of an Auto Rotation. The standard throttle linkage components can sometimes fail to allow sufficient free play in the throttle cable and achieve 100% throttle when required. Rotorway have addressed this problem by manufacturing an extended ‘H’ arm to replace the ‘B’ arm that connects to the throttle cable.
This is the kit that Rotorway supply. A new transfer shaft, new ‘B’ and ‘H’ arms and new bolts and spring pins.
From my preliminary checks on the old assembly it seemed that I would have had trouble achieving zero and 100% throttle openings at the relevant collective settings but Rotorway include new instructions on how to set up the throttle using the FADEC readout.
The build instructions call for a 90 to 95 degree angle between the H and B arms. To set this angle I used a simple protractor.
I measured the outside angle.
Then the inside angle. I subtracted one from the other and divided the answer by 2. I added this figure to 92.5 degrees to give me the correct inside angle.
Here’s the new ‘H’ arm which actually only partially solved the problem. I also needed to replace the eye bolt with a longer one. A stack of washers spaces the cable clevis to the correct position.
I machined some aluminium spacers to replace the washers and drilled the eye bolt. Perfect operation. I can now pull full collective without opening the throttle at all.
CYCLIC GAITERS
Rotorway supply a pair of rubber bellows type gaiters to seal around the cyclic lever to the GRP cover panel. I tried ‘em and they just don’t work. They’re too stiff and restrict free movement of the cyclic stick too much so I set about constructing a simple, light weight and neat replacement.
My company sells an Automotive Universal Leather Gear Gaiter glued to a rectangular chrome frame. It has a wide opening at the top secured with Velcro which is tightened with a lace cord. I discarded the frames and used the following method to make the leather gaiters fit my ship.
I rolled a piece of aluminium sheet into a tube to insert into the leather cone and spring it to size inside the hole in the GRP panel. I could move the leather cone up and down until it’s circumference perfectly matched the hole.
I machined rings of 2mm aluminium on my lathe.
The size is approximately 4 1/4 inches ID and 5 1/4 inches OD
I used the programmable readout on my milling machine to drill 10 equally spaced holes on a 4 3/4 inch PCD.
I drilled through the leather and GRP
and Clekoed the assembly together.
Finally riveting the GRP/Leather/Aluminium sandwich with countersunk rivets. It’ll be easy to push the gaiter through from above and mask up for painting. Simple, secure and lightweight.
HAND GRIP
The starter button is safely hidden under a sprung cover. The switch below is for the Landing Light and the round button on the side is a momentary push button that toggles through the radio frequencies stored in the memory. Push to talk is operated by a non-latching rocker switch on the underside of the grip.
PEDAL GAITERS
I played around with a rubber bellows -type gaiter at first but it didn’t really work. The pedals come through the floor panel leaning forward at an angle and move through quite long arc in comparison with their height. I eventually chose leather gaiters to match the cyclic ones. If the gaiters are left long and folded in on themselves there will be ample free movement and a nice draught proof seal around the pedal casting. I made the clearance holes around 5/8 inch larger then the full front to back pedal movement and a little wider than the pedal castings.
I stuffed the gaiter tightly with newspaper and settled it in the cut out, angled towards the front slightly.
I marked and trimmed the leather then drilled and Clekoed it to the underside of the panel using 3 mm washers under the Clekos. I may yet make aluminium frames to replace the washers but I may just glue and rivet it.
UPDATE:
Just a simple one. When I came to tighten and wire the collective fixing bolts, the threaded bush turned as I tightened. My solution - To file two ‘flats’ on the bush so it can be held with a large spanner whilst tightening. I also drilled through the frame and the bush for the locking wire.
I made a simple drilling jig for the safety rivets in all the cross tube ends. I used a 1 1/2 “ diameter aluminium disc with a 14.2 mm hole in the middle that locates over the 5/16 bolt head. The rivet guide holes are drilled 25 mm apart 3.5 mm from the edge. The sides are machined off so that the jig will fit in the folded Cyclic Mounting Bracket.
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