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Spartan RC Spartan RC - Quark, DS760 Gyros and other Spartan RC Electronics Factory Support


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Old 08-30-2010, 06:33 AM   #1 (permalink)
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Default Vibration through Quark cable?

Hi All,

This thread is really a follow-on to:
  1. Best position for a Quark on a 500ESP
  2. The tidiest 500ESP wiring job ever?

As reported in the first thread, I'd moved my Quark onto the boom-block on my 500ESP and was very pleased with the results. In doing so I'd run the cabling to the gyro on the outside of the frame.

I subsequently tidied up the heli's wiring, shortening cables etc, as reported in the second thread and in doing do moved the gyro cabling inside the frame. Whilst this looked a good deal better, when I got to fly the heli I found that there was a random, quite violent twitch kicking the tail perhaps 4 inches a couple of times a second.

I'd gone from the following gyro wiring:



to:



I therefore rewired the gyro allowing a more gentle bend in the cable as before and found that the twitch was fixed. I can still see a "jitter" on the tail servo rather than it being perfectly smooth, but there is no appreciable movement of the tail. The tail is certainly "locked", but the tail servo is perhaps working a little when it needn't. I then added the metal plate to see if that would make any difference as shown below:



With the plate fitted I was able to wind the gain up from 40% to 50%. I tried 55%, and although there was no wag, the tail did oscillate a couple of times, so I settled on 50% where the tail is very solid, but I can still see the servo horn jittering slightly in a steady hover.

With the heli on the bench I can tap the frame near the gyro with no effect whatsoever, but touching the cable adjacent to the frame results in a servo twitch. Also, the only apparent difference between running the cable inside/outside the frame is that the length of free, unsupported cable is greater in the latter. It seems that more vibration is transmitted via the cable that through the foam pad.

My question is, what is the preferred cable bend for a Quark (or indeed any other) gyro? A single bend? A coil (one, two, three turns)? An S bend?

On my 450SEv2 I have the cable coiled, as much to use up the length of cable as anything, as shown below, but the 450SEv2 is clearly a different beast to the 500ESP. I don't think it's feasible to wire the Quark on a 500ESP such that there is enough cable to coil it.



As a final thought... on my 450SEv2 I've used thin mounting tape. I've yet to try this on my 500ESP. Has anybody else done this? If the issue is vibration transmitted through the cable making the gyro move on the foam mounting, perhaps using thin tape, or evening thin tape either side of the metal plate would be better?

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz

Last edited by Steve Evans; 08-31-2010 at 02:00 PM..
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Old 08-30-2010, 11:47 AM   #2 (permalink)
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Funny how when making a posting here you come up with ideas… I tried replacing the thick tape with thin, giving thin-plate-thin and there was no difference in flight. On the bench tapping the cable had much less effect. So I moved the cable back inside the frame. Back came the violent twitch although not as bad as before.

I then moved the cable outside again and used a single piece of 1mm foam tape. The visible twitch was gone (as previously with the cabling outside the frame), but I could still see the tail servo jittering. Then something interesting happened; suddenly the jitter stopped!! I checked the tx timer and I'd gone over by 1 min (inadvertently pulling 90% from the pack).

But why had the tail servo jitter stopped? I'm guessing lower headspeed may have dropped a resonance, but I think it more likely that this is electrical switching noice from the ESC. I have the ferrite near the rx near the Quark's ganglion. I'm going to move it up near the ESC to see if that improves things.

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 08-30-2010, 02:06 PM   #3 (permalink)
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Moved the ferrite to the mounting holes in the side frames level with the main-shaft. I hoped this would be enough aft of the ESC and motor for the ESC lead to not to pick up any interference, but far enough from the Rx and other such stuff to not pick up interference.

RATS!!!!

It's worse than before! Tail servo jittering like mad. This is with thin tape mounting the Quark to the boom block, gyro cabling running outside the frame, ESC cable with ferrite as above running inside the frame all the way to the Rx.

Not sure if it's significant, but I'm running the ESC at 6V. Should I wind that down a bit?

Time to make myself a curry, have a beer or two (or maybe three), and sleep on it, pending some good advice from you guys!

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 08-31-2010, 01:51 PM   #4 (permalink)
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I figured that the remaining tail servo jitter was either down to vibration or electrical noise. I therefore fitted a DS760 metal plate rather than the Quark plate and things improved dramatically although there's a tiny amount of jitter remaining (some is normal I'm sure).

I also tried dropping the BEC voltage (from the standard ESC) from 6V down to 5V. That made no improvement; in fact the tail servo seemed noticeably slower and the jitter seemed to have more effect, making the tail visibly move slightly.

Looks like this is a vibration issue...

Given that a bit of mass seems to help I'm considering putting a Quark metal plate on top of the gyro; as it's clear cased I'll still be able to see the LED.

Has anybody tried both a plastic and CNC cased Quark on a 500ESP? Is the CNC cased alternative appreciably better?

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 09-01-2010, 11:12 AM   #5 (permalink)
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You are aware of the vibes on the boom block right? There are gears sitting right underneath that gyro and thats why its recommended that it not be mounted there. The Quark is one of the most sensitive gyros Ive used...especially the wires themselves. I have mine mounted on the RX tray and it worked great from the get-go. I ran into a problem when my Ice 75 caught fire and I had a little rough landing. After that I developed a vibe somewhere that effected the gyro. I believe it came from the TT boom mount because I replaced the stock one with the I2rc CNC boom mount and she flew great again. I would also recommend picking up the USB adapter for the Quark. There are many settings you can tweak in there to get that gyro to perform just the way you like. In short I have found that the Quark is EASILY effected by vibes and would definitely suggest you move it to the RX tray as the tray itself will absorb vibes that in my opinion the tt boom block amplifies.
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Old 09-01-2010, 04:09 PM   #6 (permalink)
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I'm aware of potential vibration issues as the GP780 was so bad there. Where is the advice not to mount a gyro there? Align literature shows it as the default.

I've improved things somewhat by using a DS760 plate and a Quark plate thus. Unconventional, but so much smoother!!!!



I'm tempted to invest in a better rx tray though, as that would certainly seem a better location. On the standard kit the boom-block is the only really stable platform.

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 09-01-2010, 05:54 PM   #7 (permalink)
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Steve,
Please note that friction at the belt (and gears) of the heli produces static which accumulates at the pulleys. The voltage eventually builts up to such high levels that manages to spark across a fairly large air gap. This is very well demonstrated here:

[ame]http://www.youtube.com/watch?v=4uD_mJpVI4k[/ame]

Your gyro and it's cable are the closest conductive parts for the static disharge to jump to and it is very likely gets hit by very high voltage static discarge. You can either:

* Move the gyro and cable a little further away so static jumps somewhere else (heli frames). This also explains why it worked perfect when you had the wire running on the outside.

* Preferably ground the front and rear bearings to the boom. This will avoid static build up and sparking.

Cheers,
Angelos
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Old 09-01-2010, 09:42 PM   #8 (permalink)
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Ah, so this would explain why the DS760 plate is working better! I've not heard of static problems with the ESP; only with belt drive, but this would go some way to describe why I've had gyro problems which seem to vary from day to day (and maybe with varying humidity).

Thanks Angelos, that's the best explanation I've yet had as to why I've been seeing these issues. It looks as if I'll be best advised to get an rx tray upgrade and move the gyro there.

Thanks,

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 09-10-2010, 02:48 PM   #9 (permalink)
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Right then, it's off the boom and on a nice new CF rx tray; see HERE.

Not had a chance to do more than hover in the garden yet, but no major nasties evident. :-)

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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Old 09-24-2010, 03:24 PM   #10 (permalink)
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Problem solved. I swapped the Quark from my 450SEv2 onto my 500ESP and the problem vanished. With the gyro on the CF rc tray the tail hold was perfect. No wags, twitches, shudders, wobbles, jitters... solid as a rock!

I contained Angelos at which point the most impressive bit of customer service ensued. An RMA number was issued at 8:56pm; true round the clock service, and this wasn't an automated process either. Royal Mail Special Delivery secured delivery the day after I posted it, and by 11:07 that day the gyro was on it's way back to me having been diagnosed with movement of the PCB within the case. Fitted it to my 450SEv2 and tail was spot on. Sorted!

10/10 for customer service there guys!

Steve
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Trex 450SEv2/HS65-MGs cyclic/Spartan Quark/DS520 tail
Trex 450ProV2 DFC/CGY750 FBL/DS410s cyclic/DS520 tail
Trex 500ESP DFC/CGY750 FBL/YGE-120LV ESC/DS510s cyclic/DS650 tail
Blackout 330/OpenPilot Revo with FatShark 600mW VTX, Futaba 8FG 2.4GHz
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