Goblin helicopters technical support thread

[McCollister911]

I put the maiden flight on mine just a few hrs ago. Only had enuf light to get her up once but it felt very solid, almost heavy. Got some tweaking to do. Just came from a Rex 550 so it's and big difference. I'll get and ohm meter and check mine too. Definitely wouldn't want a disaster bc of my ignorance

[alexvan]

I think that such measurements are too much influenced by the weather conditions (temperature and humidity).

[aris2024]

Static electricity development is influenced by weather conditions but the resistance of the heli is not. It is a value that does not change* unless you make a mod to the frame.

*Actually it does increase with the increase of the temp but that is not a significant change.
Its like saying that the metals get longer as their temperatures increases and shorter as the temp goes down.

[desertstalker]

Originally Posted by McCollister911

I'll get and ohm meter and check mine too.

Pointless if you use a multimeter (if thats what you mean?) they can put out a max of about 9V, no good for high resistances at all. You need a "megger" tester (good for 1000+V) to test for resistance at high voltage (static discharges are in the order of 1-30kV typically).

Disregard if you have access to the correct testing equipment.

[alexvan]

Originally Posted by desertstalker

Disregard if you have access to the correct testing equipment.

Thanks for the clarification. A cheap equipment like this http://www.ebay.it/itm/Digital-Insul...item1e6bfcf646 is appropriate?

[aris2024]

You can also ground the boom with a little cable and verify the low resistance with a simple multimeter.

[OnTheSnap]

Originally Posted by desertstalker

Pointless if you use a multimeter (if thats what you mean?) they can put out a max of about 9V, no good for high resistances at all. You need a "megger" tester (good for 1000+V) to test for resistance at high voltage (static discharges are in the order of 1-30kV typically).

Disregard if you have access to the correct testing equipment.

A megger is used by electricians as a insulation test, where your concerned that a high voltage may jump or break down your insulation. A higher voltage will not increase my 23 ohms. With such a low resistance on my goblin there is no possibility for a potential difference to exist between the motor mount to tail. Now if you measure a high resistance I agree a megger could still get you out if doing a mod if it shows you a low resistance since its able to "jump" a small barrier if it exists.

I have a matte boom for whatever that's worth.

[gww528]

Static was a major problem when the Trex 500 was released during the winter with low humidity. We used a Non-Contact Low Voltage Detector to see if we had a static problem in the first place. Example http://www.amazon.com/Greenlee-GT-11.../dp/B000FCINXE Spool up the heli without blades & run the Voltage Detector along the boom to see if you are getting static. Then you can add more grounding wire or not. This is a good detection method.

[desertstalker]

Originally Posted by alexvan

Thanks for the clarification. A cheap equipment like this http://www.ebay.it/itm/Digital-Insul...item1e6bfcf646 is appropriate?

THat should work fine, it wont be especially accurate but we dont really care in this case.

Originally Posted by OnTheSnap

A megger is used by electricians as a insulation test, where your concerned that a high voltage may jump or break down your insulation. A higher voltage will not increase my 23 ohms. With such a low resistance on my goblin there is no possibility for a potential difference to exist between the motor mount to tail. Now if you measure a high resistance I agree a megger could still get you out if doing a mod if it shows you a low resistance since its able to "jump" a small barrier if it exists.

I have a matte boom for whatever that's worth.

The low resistance you got is great, and your right that you wont need a HV tester for that but it does not need to be that low to eliminate static issues. Even several MOhm is low enough to bleed off the static charge as fast as it accumulates (so as to prevent discharge). Commercial anti-static wrist straps (the type used to protect sensitive electronic components during installation) generally have ~1MOhm of resistance between the strap and ground pin so as to prevent them being a current path in the event the user touches something live. This is ample for discharge prevention purposes.

I suspect that all people need to do to get the resistance down very low is scratch off some paint/clearcoat somewhere so that bare CF touches the metal at each end.

[JTAnimal]

Hi, I'm using JR8717HV servos for the cyclic. in the JR servo kit there was only one arm that would meet the measurements of 16mm to 18mm for the ball position. I wound up using the outermost hole as it keep the link as straight as possible. the problem is the elevator ball can just brush on the metal base (there is a little bump where the anti rotation bracket bolts to the base)

If i move the ball in one hole the arms are not perfectly straight. Advice??

Second problem - the canopy has a crack in one corner. I received my kit on the 10th and i looked at the canopy but never took it out of the plastic. I got to the point in the manual where it said to install the foam on the edge of the canopy and that is when i noticed the crack. the helicopter is not ready to fly so the canopy has not been on the heli.

I have sent an e-mail to RC galore and he replied that he was forwarding the e-mail with pictures to SAB but 2 days have passed and no word. it makes me sad to see a beautiful canopy with a crack in it, and I'm not sure i would use it for the first flight. Waiting.

[OnTheSnap]

Not that this is any consolation for your blemished canopy, but mine was perfect and after 10 flights and maybe 50 times pulling off the canopy mine has developed hairline cracks, is chipping at the canopy mount holes, and is chafing at he front of the skids. Basically normal stuff from regular use.

With something like a 3D heli, it's pretty impossible to fly them hard, use them and keep the canopy perfect for long.

Most of my heli's are pretty scarred. Canopies surviving multiple crashes put back together. I actually prefer it when my heli is decently scuzzed up since I don't feel as bad when (not if) a mishap happens.

Unless your crack is really bad, I'd just fly it.

[JTAnimal]

I think its bad what do you say. $1000 and its never been in the air and the canopy has never been on the heli.

[Scottyb410]

Well, I set the Fluke up for a one minute @ 1000v test. As suspected, it kicked out at <2 seconds basically indicating a dead short. Considering static potential is usually well above 1000v, I am not too worried about a significant resistance issue. I won't have access to our mohm meter until next week. I will repeat the same test with that for a true value.

Cheers

Scotty

[gww528]

Originally Posted by Scottyb410

Well, I set the Fluke up for a one minute @ 1000v test. As suspected, it kicked out at <2 seconds basically indicating a dead short. Considering static potential is usually well above 1000v, I am not too worried about a significant resistance issue. I won't have access to our mohm meter until next week. I will repeat the same test with that for a true value.

Cheers

Scotty

What points are you measuring between? i.e. motor mount & tail shaft

[Scottyb410]

Yes, that is correct. I also isolated the electronics (just in case)

[OnTheSnap]

Originally Posted by JTAnimal

I think its bad what do you say. $1000 and its never been in the air and the canopy has never been on the heli.

Yah that's a pretty healthy crack! Sucks.

[TomC]

Originally Posted by JTAnimal

it makes me sad to see a beautiful canopy with a crack in it, and I'm not sure i would use it for the first flight. Waiting.

Maybe you can use a bit of ca/kicker and find some green duct tape to tape over/under the crack until you get a replacement one?

cheers,
TomC

[LegndarySaiyan]

Originally Posted by JTAnimal

I think its bad what do you say. $1000 and its never been in the air and the canopy has never been on the heli.

Who did you buy your kit from? My canopy had the same tear in the same spot, was spider cracked all over the place and had paint flakes missing in spots. I contacted Helidirect and emailed them pics as soon as I opened the box and saw it. They responded quickly and said they would replace it as soon as the canopies were available to them. In the mean time I sealed the crack with ca and kicker but theres only one way to take the canopy on and off without tearing it open again.

[McCollister911]

Cut you a small strip of fiber glass and spread some resin on the inside. Lay it down and cover the top with a thin layer of resin also. It'll make the canopy thicker in that area but the integrity will be like new. Then you have 2 good ones when they send the replacement

[JTAnimal]

Originally Posted by JTAnimal

Hi, I'm using JR8717HV servos for the cyclic. in the JR servo kit there was only one arm that would meet the measurements of 16mm to 18mm for the ball position. I wound up using the outermost hole as it keep the link as straight as possible. the problem is the elevator ball can just brush on the metal base (there is a little bump where the anti rotation bracket bolts to the base)

If i move the ball in one hole the arms are not perfectly straight. Advice??

Second problem - the canopy has a crack in one corner. I received my kit on the 10th and i looked at the canopy but never took it out of the plastic. I got to the point in the manual where it said to install the foam on the edge of the canopy and that is when i noticed the crack. the helicopter is not ready to fly so the canopy has not been on the heli.

I have sent an e-mail to RC galore and he replied that he was forwarding the e-mail with pictures to SAB but 2 days have passed and no word. it makes me sad to see a beautiful canopy with a crack in it, and I'm not sure i would use it for the first flight. Waiting.

Thanks all for your comments on the canopy and i don't mean to be rude or anything but i thought this was a thread to talk directly to SAB. I still do not see any reply from them.