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Home✈️Aircraft🚁HelicopterMiniature Aircraft Whiplash & Fury 55 › Fury 55 FBL Head on Older MA Machines
09-19-2020 02:38 AM  5 months ago
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helitom

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Pine Grove, Calif, USA

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Fury 55 FBL Head on Older MA Machines
Over the last several years I have converted some of my older MA machines (Furys - Expert and Extreme, Graphite SE's, and Stratus) using Whiplash FBL rotor heads. The results in every case has been as good or better than I expected.

I recently converted another Stratus, this time using a Fury 55 FBL rotor head. The first three flights went as well as I expected with a lot of scratching my head as to "what's causing that??", linkage adjustments, and FBL controler adjustments (Futaba CGY750). Pretty standard stuff for me. Actually, all was going well as I see things. Then, on flight four, coming in for touch down, I got a terrible head wobble.

I know how to track down dampner and shim problems (I think) but the wobble got my attention as to the suitability of using a Fury 55 FBL rotor head on a machine like the Stratus. The head looks stout enough to me and the same kind of head is spun up pretty good on my Fury 55 without issue.

Anyone have some experience with this kind of set up?
The older I get, the fewer things seem worth waiting in line for.
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09-19-2020 08:52 AM  5 months ago
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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First of all... You said nothing about your FBL controller.

We know that you are using a class 50 rotor head on a class 90 machine and should be a concern only on a 3D xtreme flights.

Base on your information, let's check the FBL controller first.

/
Saludos cordiales,
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10-03-2020 01:41 AM  5 months ago
helitom

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Pine Grove, Calif, USA

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For those who may have looked at my problem, I found and corrected the culprit. System = MA Stratus with a Fury 55 FBL rotor head; Futaba 9252 servos (with the standard Futaba servo output arms) and a CGY750 FBL controller. Problem was a rotor head wobble.

Turns out that one of the cyclic servos output arm had a worn out spline. The relative uncontrolled movement between the servo output shaft and the servo arm caused the head wobble. The output arm spline got worn out because the MA supplied brass servo bearing stud had come loose allowing movement between the servo arm and the servo output shaft. Once the servo output arm spline started wearing out the relative movement continued no matter how tight the bearing stud was made.

Something else to add to your check out list.........
The older I get, the fewer things seem worth waiting in line for.
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10-03-2020 02:51 AM  5 months ago
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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I would like to see some pics...

My fury have similar configuration so, I would like to check and figure it out...

Thank you in advance!

/
Saludos cordiales,
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10-03-2020 07:02 AM  5 months ago
wjvail

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Meridian, Mississippi

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Thanks for sharing what you learned. I'm never too old to add new knowledge to my heli tool kit. There is a very long list of ways to crash a model helicopter . Your discovery is a new one (for me).

I have two X-Cell Tempests that I still fly. One of them I converted to FBL. When I converted the model, I installed MKS X8 servos and removed the MA servo braces. Beyond the specs of the X8s, I like the MKS two piece metal arms attached to an oversized servo spline. You can actually get a proper hex wrench on the retaining screw.

As for X-Cell's braces, I always though they were messy and complex. They might have served some purpose with 100 oz*in plastic servos, but when using servos with metal cases/gears and 500 oz*in of torque, they are just untidy and pointless.

Again, thanks for taking the time to post what you learned.

"Well, nothing bad can happen now."
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10-03-2020 05:13 PM  5 months ago
jbjones

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Columbus, Mississippi

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helitom The output arm spline got worn out because the MA supplied brass servo bearing stud had come loose allowing movement between the servo arm and the servo output shaft.
This is how I lost my Stratus once. That stud backed out enough for the servo wheel to disengage from the servo shaft.

Like Bill said, thanks for posting. That is an interesting project!
J. B. Jones
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10-08-2020 02:34 AM  5 months ago
helitom

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Pine Grove, Calif, USA

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In reply to the request for pix, I've attached two. First is the type of servo mount used by MA in the Fury's, Stratus, Spectra and some others. This mount is supposed to add some rigidity to the servo control system. The second pix is the brass stud provided by MA for this assembly. The stud replaces the servo arm screw that came with the servo. The stud has two functions. It holds down the servo output arm and anchors the servo to the bracket assembly over the servo. If you are using plastic gear servos the problem is that the only provided brass stud type has machine threads, not self tapping size and type. When you tighten down the stud into the plastic servo output spline to hold down the output arm the plastic fairly quickly relaxes it's "bite" into the stud because there is not much threaded area on the stud. When that attachment between the servo arm and the servo output spline becomes loose the movement between the output spline and servo arm spline quickly wears out the servo arm and the arm ultimately slips.

If you are using metal output gear servo you can Locktite the stud and maybe forestall possible failure.

The older I get, the fewer things seem worth waiting in line for.
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