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Old Oct 27, 2012, 07:13 AM
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VCTRC 3GX Flybarless 3-Axis Gyro

Keris and mhills51 pointed out this gyro (thanks guys), so I thought I would get one to see what it was like.

No surprises, it seems to be very similar to the Microbeast v1 and the HB800, again boasting sat and sBus support, without the required menu features to be able to set the sat or sBus mode, so I'm not expecting this to work, like it doesn't with the HB800. The 3GX model number is a strange choice, as it bears no resemblance to the Align 3GX, at all (thank goodness). It will just cause a lot of confusion when referring to the gyro.

It was shipped in a resealable anti-static bag (no plastic box like the retail HB800), but it was packaged in bubble wrap. It's supplied with some good solid leads, a single piece of firm double sided foam and a small plastic screw driver, for adjusting the pots.







The first surprise was it's weight. 10.9g without leads, virtually the same as the ZYX. How have they done this? The case in now entirely made of plastic. Now I have two minds about this. The weight of the gyro and the foam can definitely help to remove vibration, but if you don't have excessive vibration, then the weight of the gyro becomes your enemy when doing sudden movements or stops. I fly 4 ZYX's and have never had any issues with vibration, so I'm happy this gyro is lighter than the MB, the HB800, and the G31.

The units measurements are:
37mm x 27mm x 14mm









The only negative for me was that the metal bottom case in the MB and HB800, was also a heatsink for the two MEMS sensors (keeping them the same temperature), which can be a big advantage when it comes to avoiding drifting issues. Now there are two small plastic posts touching the top of the MEMS sensors to hold that end of the board down.



Again other gyros don't use a heatsink on the MEMS sensors (min blue Vbar for example), so this may have been an overkill by MB anyway, and we are a few years down the track from when the MB was designed. I'm sure the MEMS sensors have improved since then. We'll see when I get to fly this unit.

Looking at the internals, the soldering is very good. The part numbers have been removed from the IC's, but from looking at the HB800, it's obvious what they are. All up it looks well made with good quality components.







Bench Test
Bench tested the VCTRC FBL unit tonight. All is working well. No drift after running the unit for over 10 minutes. The servos are silent at rest. Pots 1 & 2 are working in the correct direction, but I can't tell if pot 3 is working correctly on the bench.

Like the HB800, this gyro defaults to the highest setting (blue), for most of the settings.

To save you some time reading the entire thread, here are some highlights of my posts, the last one being a video showing the stability of the unit in wind (no 3D):
http://www.rcgroups.com/forums/showp...04&postcount=7
http://www.rcgroups.com/forums/showp...42&postcount=9
http://www.rcgroups.com/forums/showp...9&postcount=36
http://www.rcgroups.com/forums/showp...6&postcount=45
http://www.rcgroups.com/forums/showp...9&postcount=78
http://www.rcgroups.com/forums/showp...5&postcount=82
http://www.rcgroups.com/forums/showp...7&postcount=83
http://www.rcgroups.com/forums/showp...0&postcount=87
http://www.rcgroups.com/forums/showp...2&postcount=92
http://www.rcgroups.com/forums/showp...&postcount=146
http://www.rcgroups.com/forums/showp...&postcount=149
http://www.rcgroups.com/forums/showp...&postcount=154

Videos:
ALZRC Devil 450 FAST: http://www.rcgroups.com/forums/showp...&postcount=154
VCTRC 450 Pro DFC (thanks zhnme523): http://www.rcgroups.com/forums/showp...&postcount=303

.
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Old Oct 27, 2012, 09:39 AM
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2Doggs's Avatar
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Excellent pics! You'll have to do us a tutorial on attaching images to posts!

Look forward to your flight tests!
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Old Oct 27, 2012, 10:37 AM
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Really nice new product thread and layout! They need to hire you as product specialist
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Old Oct 27, 2012, 02:17 PM
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Excellent BF...looking for reviews..
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Old Oct 28, 2012, 04:33 AM
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Thanks, guys. It's just my way of paying back for all of the great info I find on RCG.

@2Doggs, to add the larger image to the post, in the advance post edit screen, right click on the file in the attached file list and copy the link location. Go to the position in the file you want the image and then using the insert image toolbar button, paste the copied link. It will appear with [IMG] and [/IMG] either side of it. Use preview to see the end result.
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Old Oct 28, 2012, 08:41 AM
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Thanks BF, I'll try to edit my blogs to add some images.

I see Alibaba are showing the VCTRC at estimated $45-50 in units of 500. Always interesting to know the wholesale price of stuff.
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Old Oct 30, 2012, 02:11 AM
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I've been trying to make up my mind what heli to put this on, keeping in mind that some are keen to hear how this gyro performs.

It wont fit on the 450 Sport with my current method of having the gyro in the frame under the gyro plate. It too tall and some of the LED's would be obstructed.

I don't want to remove the G31 from my ALZRC 450 Pro, as this gyro has great potential, and I'd like to see the tail bounce issue sorted first.

So I've decide to convert my 2nd 450 Pro FB to a rigid ALZRC Devil Pro 450 FAST DFC. I'll be using this fuselage:





And probably this Tarot DFC head:


I'm not sure how long the project will take. I've speed posted the FAST conversion kit, so I can get started on that as soon as possible.

It should be interesting. This heli has Henge 933's on cyclic and a SpringRC SM-S3471M on the tail (280Hz max). The motor is a ALZRC 3800kv running a 12T, IIRC. I will probably change this to an 11T slant and a 121T main. I probably should change the cyclic servos to something a bit faster, now that I've been spoiled by faster servos on my other 450's, but I don't have any other micro servos to replace them with, at the moment.

I'll keep you advised as the project progresses...
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Old Oct 30, 2012, 05:35 AM
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I see this gyro is also being sold as a RCX (RCX07-083):
http://www.myrcmart.com/rcx-3axis-fl...er-p-5005.html

Here's a link to the VCTRC manual:
http://www.myrcmart.com/download/man...al-English.zip

And a video of the VCTRC on a 450 Pro:
VCTRC flybarless system testing (3 min 35 sec)
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Old Oct 30, 2012, 08:00 AM
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That's a shame. The VCTRC FBL unit wont fit inside the 450 Pro frame. It's just too wide, and because the Devil 450 Pro has no AR gyro tray and limited space on the boom mount (because of the FAST FG boom), it looks like it will have to go on the right hand side, just behind the motor (under the main gear). At least it will be easier to see and program there.

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Old Oct 30, 2012, 08:40 AM
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Quote:
Originally Posted by beenflying View Post
It should be interesting. This heli has Henge 933's on cyclic and a SpringRC SM-S3471M on the tail (280Hz max). The motor is a ALZRC 3800kv running a 12T, IIRC. I will probably change this to an 11T slant and a 121T main. I probably should change the cyclic servos to something a bit faster, now that I've been spoiled by faster servos on my other 450's, but I don't have any other micro servos to replace them with, at the moment.

I'll keep you advised as the project progresses...
It's a pity there isn't a 10t helical pinion - 11t gives you pretty hot gearing, and it might emphasise the slowness of the Henge servos. I really like using the gyro mount for the controller, since it makes it so easy to swap one out for another, but that fancy fuselage obviously precludes that. Looks like a nest of worms under the battery tray!
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Old Oct 30, 2012, 08:58 AM
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There is a 10t helical for 3.5 and a 9t for 3.17 http://www.oomodel.com/tarot-450-pro...t-p-63492.html

I use the 10t with a 3800 3.5 on one of mine. Infinity also carries them
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Old Oct 30, 2012, 11:35 AM
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Quote:
Originally Posted by mhills51 View Post
There is a 10t helical for 3.5 and a 9t for 3.17 http://www.oomodel.com/tarot-450-pro...t-p-63492.html

I use the 10t with a 3800 3.5 on one of mine. Infinity also carries them
Thanks for the link! I thought 11t and 12t were the only options. This makes it a lot more feasible to use the helical gears with a wider range of motors. I see they do a 10t 3.17mm, and even go up to 13t. The 9t seems like it might be a bit harsh, but maybe it's OK with helical gears.

I used the 11/121 on 4s with a 2500kv motor, and it seemed to use maybe 0.5A more than 13/150, for not a lot of reduction in gear noise, when running the same 2800HS in governor mode. I'm going to order a 10t to try with a 4s 2900kv setup.
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Old Oct 30, 2012, 03:41 PM
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Quote:
Originally Posted by 2Doggs View Post
It's a pity there isn't a 10t helical pinion - 11t gives you pretty hot gearing, and it might emphasise the slowness of the Henge servos. I really like using the gyro mount for the controller, since it makes it so easy to swap one out for another, but that fancy fuselage obviously precludes that.
The 11T on the 3800kv gives me the same RPM as the 12T on a 3500kv motor, which I currently have on two 450's.

I think it may be the reverse for the slowness of the servos. Higher head speed, more reactive, and more stable.

Quote:
Looks like a nest of worms under the battery tray!
Yeah, I didn't take as much pride in my wiring, when I built that heli, some time ago.
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Old Oct 30, 2012, 04:03 PM
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Originally Posted by beenflying View Post
The 11T on the 3800kv gives me the same RPM as the 12T on a 3500kv motor, which I currently have on two 450's.
Ah, you obviously like 'em hot then! I've yet to try much over HS3000 on my 450's.
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Old Oct 30, 2012, 06:19 PM
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I do. The G31 vib log said my 450 head speed is around 3300rpm at 95% throttle (idle up 2). My 500 pro runs around 2800rpm, and my X5 and 550 are around 2400rpm.

Re the VCTRC project. I'm going to change the tail servo to the mini HK Mi 28012DMG, I already have. I'm tempted to change the cyclic servos, as well. I don't think the 933's will last very long on a FBL heli. I'm tempted to get some DS415M's, as they should be reliable, and they're rated to 200Hz, according to BeastX:
http://www.beastx.com/service_servoliste.html

I'm surprised to see the DS410 rated at 65Hz, in that same datasheet. I'm running my DS410M's at 111Hz and 250Hz. They seem happy and they're not getting hot.
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