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Heads and Rotor Blades Heads and Rotor Blades Discussion


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Old 12-09-2018, 03:26 PM   #1 (permalink)
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Default Roban 5 blade head details

I recently got the 5 blade metal head for 10mm shafts.
The finish was impressive.
On dismantling, all the thrust bearing were greased (not something you can count on) and threadlock was mostly consistent although one of the blade grip bolts seemed to have none visible (but was still firm to unscrew)..

Here are the components in the blade grip


The "J" arms provide correct phasing and also replace the swash driver.
Here are the bearings. The arms felt a bit notchy and some had 3 shims. others had 2. A pain with the shallow pan head socket screws I find is that it's hard to get the hex driver to fit and the head is easily stripped. I gave up on removing a couple of the screws for checking - at least they seemed to be firmly threadlocked.


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Old 12-10-2018, 02:00 AM   #2 (permalink)
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Measurements:
82mm from centre to blade bolt centre
70mm diameter dome
Jesus bolt hole is approx 17 below blade centre





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Old 12-10-2018, 02:53 PM   #3 (permalink)
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looks nice, what heli do you plan to install on? and what swash do you think you will use?
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Old 12-10-2018, 03:02 PM   #4 (permalink)
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Quote:
Originally Posted by Car6on14 View Post
looks nice, what heli do you plan to install on? and what swash do you think you will use?
It comes with its own swash
https://www.motionrc.com/products/ro...ead-10mm-swash

It's going on a 600 size MD500E FunKey fuselage / T-Rex 550 frame.
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Old 12-11-2018, 10:29 AM   #5 (permalink)
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Nelson:


What gyro are you planning to use?


Don
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Old 12-11-2018, 01:22 PM   #6 (permalink)
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Nelson:

What gyro are you planning to use?

Don
Hi Don. I use the SK720.
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Old 12-11-2018, 06:27 PM   #7 (permalink)
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My personal preference would be to use much heavier duty straight turnbuckles and use the electronic phasing in the 720 to straighten up the swash to grip arm angle. I did that with my Heli-Baby with the three blade head and a slightly modified version for the MH-6. There is more than enough phasing range to use straight links but you will need to find a swash driver and a five blade swash plate with a threaded hole for the driver ball. Hope this gives you an alternative.


Don


PS: I'm moving this to the Heads and Blades section, Nelson.
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Old 12-11-2018, 06:38 PM   #8 (permalink)
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Quote:
Originally Posted by Keyrigger View Post
My personal preference would be to use much heavier duty straight turnbuckles and use the electronic phasing in the 720 to straighten up the swash to grip arm angle. I did that with my Heli-Baby with the three blade head and a slightly modified version for the MH-6. There is more than enough phasing range to use straight links but you will need to find a swash driver and a five blade swash plate with a threaded hole for the driver ball. Hope this gives you an alternative.


Don


PS: I'm moving this to the Heads and Blades section, Nelson.
Do you have reservations about the stock head links? Like so many issues here, some folk seem happy with a stock product, others are not.
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Old 12-12-2018, 12:02 PM   #9 (permalink)
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A few years ago, I was certain that I read a post on here or in scalerchelis.com where the 2mm threaded portion of the link snapped off either spooling up or in flight. The worst offenders for sloppiness were the massive clear finished aluminium "Super Scale" heads that had a very convoluted linkage to avoid the need to properly phase the head. In a sense, these "Z" links on your head are a simplification of that linkage system but they now are downloading the swash driver function to them, as well. My suggested method does require spending more money but when you think of the overall cost, it is not that bad to ensure a very solid pitch/swash linkage system. Hope this helps.


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Old 12-12-2018, 01:22 PM   #10 (permalink)
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Hmmm. Thanks for the information Don. Actually the supplied swash has several blank threaded holes, one of which is nicely centered between a pair of balls and so could anchor a swash driver. I agree that the phasing can be done via the SK720 - it looks peculiar when watching the swash respond but that's not a problem. I figure having 5 swash driver arms the load should be modest on any one. On the other hand rigid "DFC" systems can apparently incur stresses.
I was looking up swash drivers and at this size they seem to have 2 attachment points to the the swash - I wonder how they would go just using one side.
Anyway, this head does seem to have been widely used and I am inclined to trust it.

Edit - do you know of a suitable swash driver with just one attachment ball?
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Old 12-12-2018, 06:03 PM   #11 (permalink)
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I an using one drive point for my three, four, and five blade heads. Most of my two blade heads have two drive links with the one exception of a DFC head on my F3C helicopter. Take care.

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Old 12-12-2018, 06:40 PM   #12 (permalink)
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Quote:
Originally Posted by Keyrigger View Post
I an using one drive point for my three, four, and five blade heads. Most of my two blade heads have two drive links with the one exception of a DFC head on my F3C helicopter. Take care.

Don
Like the stock T-Rex 550/600 double arm driver but just using one side?
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Old 12-12-2018, 07:08 PM   #13 (permalink)
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Have a look at swash drivers from Vario and sk-rotorkopf. I like all metal ones rather than mostly plastic. Naturally, they will all have plastic/nylon links, that goes without saying. I have also used a single armed version of a Logo 500 swash driver and that worked very well on my MH-6 (TOW Defender previously) and still works great. There are more but these are ones I have or have used. Hope this helps.

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Old 12-13-2018, 07:30 AM   #14 (permalink)
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I used the swash driver from vario on both my 4 blade 500C and 5 blade 500E. It is a little pricey but the quality is spot on. Also they sell rods of various lengths to eliminate the j hooks.

Ron
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Old 12-15-2018, 10:33 PM   #15 (permalink)
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I placed the swash and head on a shaft and connected the 5 links. The 5th link did not quite match the ball position and needed slight "persuasion" to attach. On measuring I found that the balls were not exactly equally spaced which would explain the lack of smooth fit.

Next I Iooked for tension by hand turning the head while holding the swash still. At neutral cyclic all was smooth, but when the swash was tilted there was some interaction, i.e. it was difficult to hold the swash at a fixed tilt while rotating the head: the swash tilt shifted slightly with each head rotation. Conversely if the swash was tightly gripped in a fixed tilt the there was some resistance at some point in the head rotation.
I don't know if making the ball spacing more uniform and hence removing the tension needed to attach the 5th link would fix the situation. I could perhaps ask for a replacement swash.
I'll post this also on ScaleRChelis.
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Old 12-16-2018, 10:17 AM   #16 (permalink)
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With a regular head with straight linkage rods the position of the ball on the swash would not matter in terms of the resistance you are reporting, though of course it would affect flight characteristics. With the J-arms that could be different, since they act more like DFC arms in the sense that they eliminate the need for a swash driver.
I guess you'll have to ask for a replacement swash.
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Old 12-16-2018, 05:22 PM   #17 (permalink)
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I posted a question in the "physics and engineering" subforum
https://www.helifreak.com/showthread...57#post7662157
Hoping to get extra input on the DFC geometry. In swapping links around I'm not sure the swash ball spacing is making a difference - the J arms possibly also vary slightly in their angle.
I'm more looking towards a conventional swash driver and straight arms.
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Old 12-29-2018, 11:13 PM   #18 (permalink)
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I am running that same head on my G-JIVE and it has had hundreds of flights. I check it regularly and have had no issues at all.
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