Static electricity and eraptor 620

[asesso]

I recently had a castle 85 speed control catch fire in flight. after talking with the reps at castle they feel it may have been due to static electricity generated by the tail rotor belt and that this has been a problem with the eraptor 620. They recommend I ground the boom to the frame. What is the best way to do this? has anyone else had this problem?
Art

[ghtracey]

I recently had a castle 85 speed control catch fire in flight. after talking with the reps at castle they feel it may have been due to static electricity generated by the tail rotor belt and that this has been a problem with the eraptor 620. They recommend I ground the boom to the frame. What is the best way to do this? has anyone else had this problem?
Art

Now I'll give you the fact that I don't have an e620, I have a Titan, but unless there are some HUGE differences, this is a load of crap. First off, the stock frame is plastic, which is non-conductive (mostly, it may be partially conductive), you can't ground anything to it. Secondly, even if you have a Carbon Fiber frame, the aluminum boom slides into the frame and is screwed to it, already making physical contact, so it is already grounded. About the ONLY thing I could see being possible effective would be to run a wire from the tail boom to one or both of the aluminum skids to allow any static to actually go to earth when you land. Given that your heli birst into flame while in the air, making an earth ground on landing seems pointless.

My next point is that I would like to hear an explanation from them as to how they figure the boom could generate enough static electricity to arc itself over to the ESC. The logical path would be that it would travel through the TR servo to the Gyro, then to the Rx, and finally back into the ESC to ground. Oddly enough, you had no trouble with any of those components. A direct arc to the ESC would probably be a distance of inches, and I won't even bother calculating how many volts potential that would require.

The ONLY way that static being an issue makes sense to me is if the static travelled through the frame and arced from there to the ESC where it was close to the frame. In this case, you would actually want to electrically isolate the ESC from the frame, not ground the tail boom (which as mentioned above is already as grounded as it can be). There is no way to disperse static electricity in the air, it needs to be earthed (they call it a ground for a reason). The best you could do would be to connect the frame to the battery negative and I'm not real sure that's a good idea.

[V1k1nG]

The anodizing layer on the aluminium is non conductive...

The tesla generator uses a belt running in an aluminium tube, generating electricity :confused:

[ghtracey]

The anodizing layer on the aluminium is non conductive...

The tesla generator uses a belt running in an aluminium tube, generating electricity :confused:

That may explain the static, but it still doesn't explain how it could effect the ESC.

[henrik04]

Even the bottom of the E620 frame is full carbon fiber, I can't understand how this can produce a fire in the ESC. Grounding the bottom frame and the tail boom is a very good idea. Limits the electrical noise to the receiver anyway.
Simple ground coper braid wire used in electronic do a great job. If your tail boom is carbon don't forget to lightly sand the part which will be in contact with the copper braid. The same copper braid is soldered to a solder lug which is screwed to the bottom carbon frame. Use an ohmmeter to insure the continuity between the tail boom and the frame.

Finally with a second solder lug and coper braid link the [B]same[B] point to the negative of your battery.
(star connection to diminish return path value.)

I did this on my first E-620 and I intend to do it on my second one as well. My Phoenix HV110A never had a problem neither the receiver (36 MHz) or the video transmitter.
Batteries are A123 12S.

Fire is more likely due to a defective motor (or connection) which in turn ran very high current flowing through the ESC.
Hard to diagnose without the elements though.

Feel sorry for you as it is an expensive item.

Happy flying.

[asesso]

Thanks for the replies, The people at Castle were very polite and are replacing the Castle 85 but I agree the static electricity argument left me with a lot of questions. I did land the copter without damage and the fire was confined to the ESC. As soon as i unplugged the batteries the fire went out. It appeared to start from the motor side of the ESC.
My concern now is how can I make sure it won't happen again. I have been flying a trex 450 for several months with no problems. This is my first large copter with this much battery power. Should I move up to the castle 110. I am using two 5 cell evo packs. My motor after the fire appears fine with no evidence of damage even in the external wires. The battery pack voltage after the fire was also apropriate for the short flight. The dx7 radio checks out OK. The ESC and motor initialized correctly before the flight and I heard the usual beeps. For a relatively knew pilot landing the burning copter was something I would rather not do again!
Art

[henrik04]

Thanks for the replies, The people at Castle were very polite and are replacing the Castle 85 but I agree the static electricity argument left me with a lot of questions. I did land the copter without damage and the fire was confined to the ESC. As soon as i unplugged the batteries the fire went out. It appeared to start from the motor side of the ESC.
My concern now is how can I make sure it won't happen again. I have been flying a trex 450 for several months with no problems. This is my first large copter with this much battery power. Should I move up to the castle 110. I am using two 5 cell evo packs. My motor after the fire appears fine with no evidence of damage even in the external wires. The battery pack voltage after the fire was also apropriate for the short flight. The dx7 radio checks out OK. The ESC and motor initialized correctly before the flight and I heard the usual beeps. For a relatively knew pilot landing the burning copter was something I would rather not do again!
Art

And you are absolutely correct.

I would say that the HV110A gives you a nice safety margin (Current wise). It's a bit heavier than the HV85 but on such large bird I don't think you would feel the difference. (Never had the HV85 so I can't speak really).

Even if the wires look fines, I would change whatever wires carrying high current. Or at least check them with a milli ohmmeter.
Just a personal preference: You don't need the bullet connector between the ESC and your motor.

Some will probably say {What's happen if you want to change the motor?}
And I would answer [How often do you need to do this?]

So solder the wires from motor to ESC and you'll win a lower resistance connection as well as add a safety margin. (Don't forget quality heat shrink tubing to isolate correctly the three wires)

Which motor do you run?

Happy flying.

[asesso]

I am currently running the thunder tiger ripper motor on the heli
Art

[henrik04]

If I may suggest, I would test it "on the bench" applying some mechanical load to it, before flying with it.
As the cause of your 'incident' it is not really obvious, one is never too careful.

Hope everything will be fine.

Happy flying.

[Ticidytoc]

That may explain the static, but it still doesn't explain how it could effect the ESC.

We have been popping the Castle stuff in our logos, the static blows the opto board on the ESC. I have been using dry graphite lube on the belt to stop the static issues on the Mikado and it has been working perfectly as long as you stay on top of this with the lube. Both the 620 and the Logos use the same belt. Some have switched to a neoprene belt as a replacement and have had good luck with this as a solution to the static issue.

[Finless]

Yep I went through 5 Castle 85HV on my eraptor 620. I finally gave up using them. Every time one failed was because the process board would go south. I would fly... shoot an auto and land. Unplug and the next time I would go to fly either it the ESC was dead or some other problem.
Up until know I never heard the static business effecting them but after going through 5 I just gave up an used another ESC and have yet to have a problem.

So in my opinion it could be static but if it is, then Castles board is too sensitive then. No other ESC seems to have this issue on my Raptor.

But to answer your question. Scrape the coating off the boom and where it goes into the boom block put a wire there so when you camp the boom the wire is pinched where you scraped the coating off. Now run the other end of the wire to a screw that bolts the carbon frame to the upper frame. Make sure to sand the coating off the carbon in this are as well. Once all attached check continuity between the frame and the boom with a ohm meter.

Bob

[asesso]

Thanks for the replys. Would it be safe to place a lug and a small sheet metal srew into the boom to set up the ground, or would this foul the belt?
Art

[stevehonn]

I had huge radio interference problems with my E550 which resulted in a full PCM lockout and major crash. I removed the switching BEC I had fitted and used a 2S lipo and Align regulator and fitted a brand new JR PCM reciever and still had issues. I finally attributed this to static from the belt drive but cured it by moving to 2.4ghz system instead - the static never caused any problems with the Ace ESC fitted.

[ghtracey]

I had huge radio interference problems with my E550 which resulted in a full PCM lockout and major crash. I removed the switching BEC I had fitted and used a 2S lipo and Align regulator and fitted a brand new JR PCM reciever and still had issues. I finally attributed this to static from the belt drive but cured it by moving to 2.4ghz system instead - the static never caused any problems with the Ace ESC fitted.

I just listened to one of the Inside Heli podcasts last night where one of them discussed the complete opposite. He had static issues with 2.4GHz, but not 72MHz.

Static buildup causing interference I can understand, but I still can't see how it cooks the ESC unless there is some design flaw. In this same podcast the Castle Creations rep they were interviewing mentioned the static problem with the ESC and that they made changes to the design to resolve this. I don't recall seeing reports of any other brand of ESC bursting into flames due to static.

I think though that on both my Titan and e325 I will be grounding the tail boom to the negative post on the battery. It gets pretty dry up here and I'd prefer to prevent a possible interference problem before it happens.

[nzreg]

Thanks for the replys. Would it be safe to place a lug and a small sheet metal srew into the boom to set up the ground, or would this foul the belt?
Art

Take my advise, don't use a self tapping screw for this, they will vibrate loose over time.
I also attached an earth (ground) cable to the motor mount as well, so I now have the boom and motor cables terminated onto one bolt on the carbon frame.
good luck.:thumbup:
Should have said I then have a single cable to the negative on the battery.

[henrik04]

For better conductivity, one can use the spray from Electrolube Ref: NSC400H. Farnell part number: 521 450.

This spray is a Nickel conductive spray and can be use to improve conductivity inside anodised tail boom for example.

I don't use anodized tail boom but Carbon fiber one.

Anyway hope this will help..

Happy flying.