Goblin helicopters technical support thread

[mahbouni]

Originally Posted by TomC

BTW for a technical support thread, their ain't much tech feedback from Mr. Goblin

Maybe Mr Goblin is busy celebrating the Chinese New Year

[TomC]

Originally Posted by mahbouni

Maybe Mr Goblin is busy celebrating the Chinese New Year

Ya, maybe, but he has not posted anything since 3 Dec 2011, so it must be a good party, lol!

Cheers,
TomC

[gww528]

Originally Posted by TomC

I just checked out one of my CF booms with an ohm meter and I assure you it is not conductive. Maybe SAB are puting metal bits in their booms CF matrix? You can do the same test with any of your CF frames and I think you'll get the same result.

I have reviewed all Goblin videos from their website and the only aileron tic-tocs in which the boom was not bobbing up and down was with Bert's low rpm (~1700) video.

Like you say, all should be revealed pretty soon once the first batch guys are up and flying.

BTW for a technical support thread, their ain't much tech feedback from Mr. Goblin, lol!

Cheers,
TomC

Carbon Fiber is conductive. If you place your probes on the outside you may not get any conductivity (sometimes there is a coating on the carbon) but if you place the probes between two holes in the frame it will conduct. That is why Bert has a screw in the tail with a wire connected. The screw goes into the carbon fiber were it is a better conductor.

[TomC]

Originally Posted by gww528

Carbon Fiber is conductive. If you place your probes on the outside you may not get any conductivity (sometimes there is a coating on the carbon) but if you place the probes between two holes in the frame it will conduct. That is why Bert has a screw in the tail with a wire connected. The screw goes into the carbon fiber were it is a better conductor.

OK, technically speaking you are right. CF is conductive but it's a pretty poor conductor of electricity, a lot poorer than say Aluminum. Also, we do not actually use pure CF, we use CF reinforced polymers (like epoxy) and these tend to be made up of wraps of CF cloth, that may also have polymer coatings. A lot of these polymer coatings a very good collectors of static charges btw.

So, yes you are correct in saying that Bert's CF boom will conduct some (a lot better than none) electric charge. Is it enough to keep up with the static buildup? I'm not too sure. Sounds like it has not been a problem for him. Static buildup is generally only a problem if you fly in very low humidity climates so probably not an issue for most of us.

Cheers,
TomC

[Mystic3D]

Originally Posted by TomC

OK, technically speaking you are right. CF is conductive but it's a pretty poor conductor of electricity, a lot poorer than say Aluminum. Also, we do not actually use pure CF, we use CF reinforced polymers (like epoxy) and these tend to be made up of wraps of CF cloth, that may also have polymer coatings. A lot of these polymer coatings a very good collectors of static charges btw.

So, yes you are correct in saying that Bert's CF boom will conduct some (a lot better than none) electric charge. Is it enough to keep up with the static buildup? I'm not too sure. Sounds like it has not been a problem for him. Static buildup is generally only a problem if you fly in very low humidity climates so probably not an issue for most of us.

Cheers,
TomC

Yes Bert being in FL would be in high hunidity, as in Houston where I live.

This is really not a big thing to fix. If I don't get 0 ohms on the meter from tail to front pulley I will epoxy a thin wire down inside the boom, plenty of room. I learned early on you can theorize all you want and that's good casue it gives you a list of things to check. Assuming anything is okay becasue someone else says so does not work for me personally.

[TomC]

Good way of thinking imho.

If it were me, I'd probably also run that wire to one of the motor mounting bolts rather than just relying on the whole metal frame carrying the charge since many of the Al alloys used are not that conductive either.

Cheers,
TomC

[Mystic3D]

Originally Posted by TomC

Good way of thinking imho.

If it were me, I'd probably also run that wire to one of the motor mounting bolts rather than just relying on the whole metal frame carrying the charge since many of the Al alloys used are not that conductive either.

Cheers,
TomC

Good Point.

It's like my flying buddy, run 8.4v to DS-610's no problem, a lot of guys doing it, opps, servo failed in flight(true story), $400 Crash, Geez wonder what could have accelerated the servo failure? Someone said it was okay....not to follow specs

[rcflyerheli]

Originally Posted by TomC

OK, technically speaking you are right. CF is conductive but it's a pretty poor conductor of electricity, a lot poorer than say Aluminum. Also, we do not actually use pure CF, we use CF reinforced polymers (like epoxy) and these tend to be made up of wraps of CF cloth, that may also have polymer coatings. A lot of these polymer coatings a very good collectors of static charges btw.

So, yes you are correct in saying that Bert's CF boom will conduct some (a lot better than none) electric charge. Is it enough to keep up with the static buildup? I'm not too sure. Sounds like it has not been a problem for him. Static buildup is generally only a problem if you fly in very low humidity climates so probably not an issue for most of us.

Cheers,
TomC

Ask my 700 frames where my 12s batt leads touched them. I don't think taking a metal wire and placing it across the terminals could have created a bigger light show. It also melted about 1/8 dimple in the frame. That CF was conductive.

[desertstalker]

Originally Posted by TomC

Good way of thinking imho.

If it were me, I'd probably also run that wire to one of the motor mounting bolts rather than just relying on the whole metal frame carrying the charge since many of the Al alloys used are not that conductive either.

Cheers,
TomC

They dont need to be very conductive, we are talking about tiny amounts of energy at very high voltages, even slightly damp air is conductive enough. CFRP is likely 100s of times more conductive than that (if not 1000s) and will be fine.

Basically if your multimeter shows anything other than infinite resistance between tail and heli frame it will be more than sufficient to prevent a static charge building up to discharge level (10+ kV at least, 100kV is easy for static charge, you wont even feel less). In fact anything that would fail mains isolation testing (done at 1000V typically) would be fine here.

As to all the crapping on the tail belt; a TT is in no way more efficient than a belt, not at flight speeds, this has been tested numerous times. A properly designed belt has all the power handling capacity of a TT drive (the goblin tail belt design is excellent, large pulleys a wide belt and an auto-tensioner). If both are executed properly TT and belt have the same performance, a poorly designed belt system will have poor power-handling and a badly designed TT system will produce excessive vibration (see align for examples of both).

[TomC]

Originally Posted by rcflyerheli

Ask my 700 frames where my 12s batt leads touched them. I don't think taking a metal wire and placing it across the terminals could have created a bigger light show. It also melted about 1/8 dimple in the frame. That CF was conductive.

After you changed your underwear I hope you worked out the type of connectors you should be using, lol!

Cheers,
TomC

[McCollister911]

Ok Tom and Mystic, forgive me for asking such a rookie ? But I've been watching all of these threads for months and I this has been a concern of mine for a while now. I've heard several times b4 ab grounding the boom if the heli is belt drive. I've only had one belted heli and it was my first build begginning of last year 450sport. I live in Louisiana where humidity is usually high. I never grounded the boom and also didn't ever experience any problems. The helis I am currently flying are TT so I haven't thought of it much since I've gotten rid of the 450. My ? Is ab the static buildup. The belt is ran on Pulleys that are certainly conductive. So I'm guessing the static comes from the belt rotating within the boom? If this is correct, then is the charge substantial enough to make an arc between the 2? And if this happens how does it affect the gyro? Again I apologize for asking such a ? That should be common to me by now Any explanation is appreciated Another ? Would be ab the wire epoxied to the inside of the boom. Would u use a thin bare wire along the whole length of the boom on the inside, grounded to the frame and tail caseing? And why would u need to take it all the way to the motor mount screw? since this is where the bulk of the power goes will it give the best ground? Please set me straight on this one I have a small group of guys in this area who started flying together and I have become the go to guy for them(scary). Ignorance on my part can become expensive for us. Thanks in advance

[Scottyb410]

Originally Posted by desertstalker

Basically if your multimeter shows anything other than infinite resistance between tail and heli frame it will be more than sufficient to prevent a static charge building up to discharge level (10+ kV at least, 100kV is easy for static charge, you wont even feel less). In fact anything that would fail mains isolation testing (done at 1000V typically) would be fine here.

This is a neat idea, When my Goblin arrives, I am going to take it into the lab and fire 1000v through the tail with the megger. The results will be interesting to see. I well imagine the Fluke will dump at 2V. I will try a megohmmeter test from tail to motor-mount after that.

Interestingly enough, I noticed that Gates publishes a conductivity testing protocol for their belts.
http://pdf.directindustry.com/pdf/ga...77357-_16.html


These tests should put the whole static issue to bed once and for all.

Scotty

[Mystic3D]

Originally Posted by McCollister911

Ok Tom and Mystic, forgive me for asking such a rookie ? But I've been watching all of these threads for months and I this has been a concern of mine for a while now. I've heard several times b4 ab grounding the boom if the heli is belt drive. I've only had one belted heli and it was my first build begginning of last year 450sport. I live in Louisiana where humidity is usually high. I never grounded the boom and also didn't ever experience any problems. The helis I am currently flying are TT so I haven't thought of it much since I've gotten rid of the 450. My ? Is ab the static buildup. The belt is ran on Pulleys that are certainly conductive. So I'm guessing the static comes from the belt rotating within the boom? If this is correct, then is the charge substantial enough to make an arc between the 2? And if this happens how does it affect the gyro? Again I apologize for asking such a ? That should be common to me by now Any explanation is appreciated Another ? Would be ab the wire epoxied to the inside of the boom. Would u use a thin bare wire along the whole length of the boom on the inside, grounded to the frame and tail caseing? And why would u need to take it all the way to the motor mount screw? since this is where the bulk of the power goes will it give the best ground? Please set me straight on this one I have a small group of guys in this area who started flying together and I have become the go to guy for them(scary). Ignorance on my part can become expensive for us. Thanks in advance

The root problem with belt driven heli's is the build up of static electricity, when you have a non conductive belt it builds up a charge similar to a van de graff generator(In case you wanted to research it).

The symptom of a heli that has a build up of static electricity that makes it's way to the electronics shows itself in "glitches", typically gyro's, Rx's will experience a brief "glitch", could be tail kick, strange movement of FBL, loss of RF for a split sec.

The solution is to eliminate the build up of static, By grounding both ends of the pulley you ensure they are always at the same potential energy thus eliminating static. The reason for also grounding to the motor mount is this is the best ground for the the entire heli, largest mass of conductive material.

A good example is a Mikado Logo, ground wire from tail case to AL Boom, from AL Boom to Motor Mount, problem solved.

[TomC]

McCollister911,

Since you live in a humid climate I would not worry about grounding your boom, esp on a small 450 sized heli. If you notice your tail gives the odd unexpected hard jerk you might suspect your belt is generating a bit of static. On my old 450 I used to use a soft builders pencil and rub in on the top of the belt ~ every 25 flights. This seemed to help. Also, make sure your belt is tight enough so it's not slapping the inside of your boom (helps if your boom is straight too btw, lol!).

Still having problems, follow Mystic's advice, it's very sound imho.

Cheers,
TomC

[McCollister911]

[TomC]

Originally Posted by tunner777

Hi when will the red one be avalible I am busting to get one

I want a hot pink one so I can name it "Goblin Barbie" after an old GF, lol!

Cheers,
TomC

[liam-b]

Originally Posted by goblinhelicopter

for now, Goblin 630 is different in:

boom
tail belts
tail pulley
damper

for now, Goblin 770 is different in:

boom
tail belts
tail pulley
main shaft
damper

The Goblin 700 production will be very similar to the picture attached.

Goblin helicopters.

hi sorry if this has being asked but would it be possible to convert the goblin 700 to the 770 when available ? or will there be any kits offered ? thanks

[gww528]

Originally Posted by liam-b

hi sorry if this has being asked but would it be possible to convert the goblin 700 to the 770 when available ? or will there be any kits offered ? thanks

There is suppose to be a Goblin 770 & also 770 upgrade kit. The upgrade kit will have a longer boom, new frames & canopy.

[Thunder Fighter]

Originally Posted by gww528

There is suppose to be a Goblin 770 & also 770 upgrade kit. The upgrade kit will have a longer boom, new frames & canopy.

I hadn't heard about the new canopy and frames. Earlier posts said Boom, belt and tail pulley in the upgrade.

//Dennis.

[rcflyerheli]

Originally Posted by TomC

After you changed your underwear I hope you worked out the type of connectors you should be using, lol!

Cheers,
TomC

Yes I did. I needed a one inch extension from my pack leads to reach the ESC leads, and I left both of them on the pack when i slid it in from the front. I never dreamed first that the batt slider would trap both leads exactly so as to defeat the HS tubing over the outside of the connectors, but apparently, that is what happened.

The heat melted a 1/8" notch in one of the leads, and the above mentioned dimple in the edge of the frame. Fortunately, I the pack tray had not locked and I Immediately jerked it forward to unbridge the leads.

Now I only insert the packs with one extension in place, and now that I know about it, carefully watch the position of the bat wires when inserting the packs.

Not to digress from the thread, but Align CF definitely is conductive.