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« Reply #25 on: May 14, 2009, 07:47:55 PM »
RotorZone
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Thank you Sahil.

There are a few of things that came to my mind that I forgot to mention earlier.

Pinions: There is also a 10T pinion for the 3D maniacs. This will trade even more power for a shorter flying time.

It was probably not clear in the pictures, the servos are fixed by self tapping screws that thread on to the frame itself. There is no servo nut like in knight 3d. The standard size tail servo is the only one that uses plastic servo nuts. The mini tail servo does not use them. As with any self tapping screw installation, it is important not to over tighten the screw and strip the threads in the frame. If you do manage to do that somehow, you could replace with a bolt and nylock nut.

The overtightening thing applies to all heli assemblies irrespective of brand and also for bolts/machine screws. Don't be a gorilla tightening them. They are manufactured for a max torque specification, if you force them beyond that, there is a possibility that the bolt head will shear off. I learned this the hard way, but fortunately on the bench, not during a flight. The screws are not supposed to held by the tightness, but they should be snugged just enough and should be held in place by using thread lock. Make sure the threads are cleaned with any alcohol to remove oil residues before using thread lock. In short, always use thread lock when installing screws onto metal parts. You don't need to use a lot of thread lock, it just makes them more difficult to remove. You just need enough to wet 4 or 5 threads. I'm a bit more generous on parts that vibrate more like engine mounts. My bolt head shearing incident was due to over tightening and overuse of thread lock. It just wouldn't budge when I tried to remove it and finally the head just sheared off. However this incident convinced me that thread lock is doing its job very well. I use the blue one from anabond. The thread lock attacks some types of plastics, makes them brittle and ends in a slow failure, so never use them on plastic.

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« Reply #26 on: May 19, 2009, 12:14:04 AM »
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Neat one RotorZone, nice build log, pics and details. All the best Rajesh!
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Its better to Crash while Learning on a sim rather than Learn from Crashing on the field
 

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« Reply #27 on: May 21, 2009, 09:11:24 PM »
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Tail assembly out of the bag. The metal tail case is standard and is open for easy inspection. There are two shims provided in the bag. These are for taking out any play on the shaft. Mine didn't have any play, so I did not use them.

14052009278.jpg
Tail assembly
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« Reply #28 on: May 21, 2009, 09:12:30 PM »
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Warning on the tail belt not to crimp it while passing it through the tail boom. Crimping it could lead to premature failure.

14052009282.jpg
Belt warning
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« Reply #29 on: May 21, 2009, 09:14:09 PM »
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The tail assembly is fixed on to the boom by the two M2 bolts you see on the side. The boom should be fully pressed in while fixing the bolts. The manual asks you not to drill the boom and let the bolts make its own holes. I was apprehensive that this might deform the boom. Anyway I thought I'll respect the wisdom of the designers and screwed in the bolt slowly. It did work perfectly. I kept pressure pushing in the boom while threading it, this also should have helped the boom retain its shape.

Tail assembly shots showing lever and slider mechanism. There is absolutely no slop in this mechanism. Another feature that is not seen here is that there is a thrust bearing and radial bearing inside he blade grips. They are lubed already from the factory.


14052009283.jpg
Tail assembly
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« Reply #30 on: May 21, 2009, 09:17:03 PM »
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You need to take out one of the bolts to fix the vertical fin. So fix the tail fin before applying loctite to the bolts.

At this time the tail rod guides are also slid onto the boom. The guides are split ring and there is a screw to tighten it over the boom. If you forget to put in the guides at this stage, don't fret, they are quite flexible and you can snap it over the boom without removing the tail boom later.

Compass model helis have a little longer vertical fin, this gives the tail blades more clearance from the ground and saves the blades in case of a hard landing.

19052009305.jpg
Vertical tail fin and tail control rod guides
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« Reply #31 on: May 21, 2009, 09:19:50 PM »
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The main gear and auto rotation hub comes already assembled. I pulled out the hub to check if the one way bearing was lubed and indeed it was.

The gear has a recess that hold the hex nylock nut for the jesus bolt. In case you are not aware, it is called the jesus bolt because all the weight of the heli is supported by this one M2 (M3 in the 50 size helis) bolt. Just this one bolt coming off will detach the main rotor from the heli frame. Imagine the stress the bolt has to take when the 3D pros are flinging the heli around  Shocked. Some of you are going to be squirming a bit when you are around a screaming heli next time I guess Grin

Keep checking this bolt often and change it after every crash. I have seen it backing off over time in other helis. Also it is very important not to overtighten this bolt that could result in bolt shearing as I explained in an earlier post. Since there is plastic gear over which the bolt tightens in this case, the deformation of the gear is the more likely result of overtightening than shear.

19052009307.jpg
Main gear and autorotation clutch
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« Reply #32 on: May 21, 2009, 09:21:29 PM »
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There are two holes on the main shaft. The end with the hole nearer to the end is where the head goes.

There is a collar on the main shaft that should be snugged under the top bearing. There is a ridge on one side of the collar, this is the one that should go on the bearing side. This will ensure the collar is snug against the inner race of the bearing and the outer race and shield can rotate freely. I donn't tighten the collar bolt at this stage, it will be done as one of the last steps. Make sure there is no up and down play on the shaft when the collar is tightened. Also don't forget to use loctite on the screw. You might wonder if the collar will slip, but that has not happened yet for me on knight 3D for with much higher loads.

The motor mount is held by two screws. Loosening the screws allows you move the motor mount to adjust the gear mesh. I will cover the gear mesh adjustment later. Also don't forget to loctite the motor mount screws after final adjustment.

19052009310.jpg
Main shaft
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« Reply #33 on: May 21, 2009, 09:23:10 PM »
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Will cover the setup later. Just the pictures for now. Everything in the head, washout assembly and swash is metal.

19052009320.jpg
Head assembly
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« Reply #34 on: May 21, 2009, 09:24:36 PM »
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More pics

20052009324.jpg
Head assembly
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« Reply #35 on: May 21, 2009, 09:26:33 PM »
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Metal swash plate and wash out assembly.

There is just one phasing pin in the washout assembly unlike in bigger helis.

20052009327.jpg
Swash and washout
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