Zapping static gremlins

In discussing my recent travails with the electrical gremlins in my HDX500 on Helifreak, Slyster offered up the notion of static discharges being responsible. This makes sense and I had given it some thought the first time I dealt with this a couple of years ago. That's when I started spraying the tail tube with lube. Random electrical parts getting zapped, and often affecting the servos, for the most part this seemed in retrospect to solve the problem. But it still happened though rarely, and as I noted zapped a servo recently. Maybe routinely spraying the tube with silicone is not enough; others have describe sparks despite the lube.

 

So I decided to up the game. I don't want to spend $50 on two G-force static wicks. So I grounded the tail boom, which acts like a van de graaf generator, hence the static problem, to the motor block using descriptions others posted on the web. Now the boom is essentially grounded to the battery (truly grounding it directly to the battery would require another wire to the neg lead of the battery, but for all intents and purposes its grounded).

 

Here you can see the entire grounding run from the screw in the tail boom peeking out on the right to where it snakes under the gyro platform and out the forward side to a bolt, then over to the top bearing block, and then down to the motor block where it ends on the aft motor bolt.

 

The metal boom is painted blocking conduction, and the block on the tail is aluminum, which is conductive. I drilled a small hole in the boom and set a screw just into the metal (avoiding the belt inside). The copper wire is wound around the screw and a dot of solder secures it. The wire runs under the gyro platform.

 

and comes up the other side. The first segment ends here, where I sanded the frame (so it also grounds to the frame) and attached the wire, the screw set into the aluminum head block. If I had planned this better I might have run one wire with spots of insulation removed to expose the wire, but, meh. So I start another wire there and ran another segment under the top bearing block...

 

and down inside the frame to come out and end attached to a motor block bolt, grounding the tail to the motor.

 

 

Hopefully this will cage the gremlins and I won't have to revist the magicla electrical mystery tour with random electrical failures!

 

UPDATE (3/13/13): I realized that I had put the screw on the boom in a place where the belt has made its turn and is in danger of rubbing. Psylence on Helifreak also pointed this out, and it convinced me to move it, so today I moved the tap to the top and out of the way of the belt. Cut a steel servo screw very short.

 

 

 

Posted with Blogsy

It always starts small...

And by the time you are done you've nearly disassembled the whole thing and spent hours solving a problem you didn't know you had when you started.

 

I took the HDX 500 down from the wall to see if the failsafe was set properly, after reading a couple of posts on HeliFreak. I noticed that the throttle stuttered just before mid-throttle. I am not sure, but think I have seen this before with this heli. I decided to change the ESC out for a HURC 60A opto ESC I have. I remember this HURC ESC because it works fine on my planks, but I wasn't able to program it with my Hobbywing programming card, like I can other HURC ESCs. I also am not sure I didn't recently fry my Hobbywing card... So I ordered a HURC card and its in the mail.

 

I set up the heli as it was, knowing that not having a soft start without blades wasn't a big issue, and the stutter step was gone. And then I noticed the twitching servos... I have had this problem before on the HDX and have never really sorted it out. I would change a part of the electrical harness and it would go away. This time it was the pitch servo. It was somehow shorting out the entire system, causing the other servos to twitch and browning out the receiver. It took me a day to isolate it this time. Needless to say I also have a 60A ESC-SBEC and a new receiver coming because I wasn't sure if they were the problem as I troubleshot it. I am now waiting for the HURC programming card, and if I can't program the HURC 60A I will swap the ESC and BEC out for the one coming in the mail and hope I didn't burn out the Hobbywing card.

 

Along the way I found out the tail rotor had a bent feathering "shaft" and needed to be replaced. It was subtle in flight but very obvious on examination. I was isolating any vibrations I could find. So those parts are coming.

 

As for the extra receiver... maybe I will build that HK600 or Winrc 600 after all. Wouldn't want a perfectly good receiver go to waste, now would I?

 

Posted with Blogsy

Rolling Gear and Nacelles Back In Business

I finished up the nacelles, and they look so much better further forward. As I described, I lengthened the wheelbase.

 

Initial installation

 

Current Installation

 

 

 

Sweet!

 

Posted with Blogsy

EXI 450 FBL Repaired

Yesterday I had some issues with the EXI 450 FBL that resulted in a fractured swash follower arm and a displaced aileron ball link.

 

Today I replaced both swash arms (they have to be the same size and aren't exactly standard, so to keep them the same I had to salvage two spares and replace them). I fixed the displaced ball link, and removed the blades. I test spun the system and found that the main shaft was bent. I replaced it. I also checked the feathering shaft, since a bent main often means a bent feathering shaft, but it was fine. So I cleaned up the bearings and re-greased them, put everything back together. New balanced blades put on, re-zeroed the pitch (whenever I do anything to the rotor head I always recheck the swash. I find that when I make sure both blades are zero at zero pitch I never have to fuss with the blades being off in tracking). Set her up for test spin, everything sweet, tracking fine, balanced and vibration free.

 

I still don't know for sure if the follower arm failed first or I crashed it through pilot error (I am still a beginner heli pilot, after all), but things were going just fine until they weren't.

 

Posted with Blogsy

At least I flew something...

30 degrees today, but a light breeze and crystal clear skies. There was no way I wasn't going to fly something. I was a little worried about plastic brittleness in the cold, as I had seen others run into these problems. I was right to be worried, but at least it didn't hurt much.

 

Wingmasters has changed their keys at the first of the year, but since I am only going to be here for a couple of months I didn't want to go to the trouble to get a key or pay for a year. I had found a place to fly behind Kettering Junior High School in Kettering, Ohio. School is out this being a Saturday, so I knew it would be safe. As I drove up, I saw A guy named Joe who was flying a couple of micro foamies (and doing a pretty good job too!).

 

I took the EXI450 FBL up first. hovered her for a few seconds, and the tail kicked over a couple of times uncommanded, but she settled down and I walked and hovered out to the field from the parking lot and took her around for a few circuits and figure eights. I began a turn in and she suddenly stopped flying and dropped as I hit Hold. inspection revealed one of the swash follower arms snapped off at its weak point where it Y's onto the swash arm of the FBL head. The aileron ball link on the servo also popped off. One blade delaminated when it hit the ground. I haven't checked the servos yet, tomorrow's project.

 

 

The upper line points to the swash arm, and the lower one to the ball link.

 

 

 

 

Video of the flight. Sorry the heli is so far away...

 

 

I put her away and brought out the HK500cmt. This would be her first flight since I put the rolling gear on, and I was curious how that would go. On setting her up I found that despite having rebound her when I reset up the servos and the BeastX when I updated the Airware on my DX8 (in the update you have to rebind and reset all the servos...). So I rebound her, and then had to reset the throttle limits. Spun her up, and she spun herself down. No power... These are all fresh batteries. When I got home I found the cells were all down to 3.84v. Put a fresh set on and she powered up fine. The BeastX was doing some odd things, but they seemed manageable. On flipping into flight mode from normal she pulled hard right and I had to put in and hold a bit of left aileron. When I brought her down, set her down and flipped out of flight mode, she pushed over to the right and then left, a blade struck, and the tail blades touched. The plastic tail blades snapped off clean at the hubs... cold had made them brittle so instead of chipping they snapped clean off.

 

 

 

 

One of the things I noticed was that the gear were leveraging and twisting against the frame, and it had come loose, making the frame dip down in front. I decided to remove the gear, and thought about putting the skids back on, but opted instead to rotate them forward increasing the wheelbase, and set them up with another wood block this time attaching the gear so that the attachment point is behind the nylon gear, and a second wood bar is in front absorbing the forward leverage forces. I attached a wire tie to this to further stabilize it. I had replaced the base of the frame since the previously repaired landing gear supports had worn and broken and were not repairable. This time I bolted the gear to the frame instead of using wood servo screws I had used previously. This is solid.

 

 

 

 

 

 

 

I have to rework the nacelles, and this work isn't done. I have to refinish them having refit them to the now forward sweeping struts. I hope this works out as I rather like them.

 

Joe, if you read this, it was a pleasure to meet you and I should have given you my email address. Hope you grow into the hobby!

 

Addendum 2/23/13: I read up, and the BeastX, and likely any MEMS based gyro, can operate at cold temps. The key is giving it plenty of time to acclimate. I took the HK500cmt out this afternoon and I think did not give it enough time. It turned on lift off, the tail jerked a couple time, then turn in a slow roll and pirouette out of control. Hit hold, only lost the main blades. Stupid is as stupid does. Tomorrow I may try again, but allow it to sit for half an hour.

Posted with Blogsy

DX8 won't bind...hope its the antenna.

Decided to brave the 27 degree weather and light winds and put the EXI450 FBL up. Ended up freezing while trying to figure out why it would bind, drop bind, but not set off the drop blink on the reciever.

 

 

I wrapped up and went home and trouble shot the bind issue. I found my radio would not bind, with any of my helis. It bound with my Sim Stick on my Phoenix sim however, before the antenna broke again. In Bind mode it would hang for several seconds in BIND, then TRANSMITTING, which it has nev done... and then reboot into the model. Meanwhile the reciever would keep on blinking.

 

I had noticed that the antenna wasn't attached at the knuckle earlier, and had snapped it back on. I wondered if the wire had become disconnected inside the radio (the fact that the wire is so long in the pic above shows it wasn't internally plugged in anymore). In trying to fix it I accidentally cut the wire with a screw as I was thinking it was a bad idea to do what I was doing because it was likely to cut the wire. Crap. Tried soldering it, but the distal end was too close to the plastic antenna (broke toow short on the antenna end), and couldn't get a decent solder. I also wasn't sure how much tolerance the antenna has for being shortened but suspect there isn't much problem with a 2.4ghz quarter length antenna bein a mm short). But there is a problem for it being 1/3 its length. Not doing the math, I really don't know how short it could be, but even when I did find the plug disconnected inside, it still wouldn't bind.

 

 

Getting the back cover off this thing was a PITA. You have to remove the usual screws, then peel off the rubber hand grips, all four if them, to get at the last two screws and release the sides. Not sure how I am going to get it to stick back together.

 

I replugged the antenna wire, not sure when it had come unplugged. Was it the problem I had in the field? I didn't go about this as methodically as I usually do... Was it the software upgrade? I don't recall but I am pretty sure I had to rebind the aircraft with the radio when I upgraded the Airware on the DX8.

 

So I ordered an new antenna from A Main Hobbies. I will replace it, put the radio back together, and hope that's all it takes to get the bind problem solved. I hope that the sign was TRANSMITTING, that the antenna is the problem.

 

Please... let this solve the binding problem. Grounded for now.

 

UPDATE (2/4/13): The antenna came in on Saturday, and I installed it today (thanks A Main Hobbies for shopping so fast!). It was very, very easy to replace. The instructions are available on the interwebs, and a copy comes with the antenna. Took a couple of minutes, a couple of screws and that was it. The grips, which I worried about getting to stay in place as I had to divide the double sided tape holding them in place, went back on without a hitch, and laid down perfectly, no issues. I didn't have to replace the tape. You have to carefully direct the rubber pegs into their holes and the grips return to their stock position with a little coaxing of the edges.

 

Fired up the transmitter and she bound immediately to the reciever! The problems were all related to the antenna. Problem solved!

 

Posted with Blogsy

If they could wag their tails they would...

They want to go out to play. Maybe tomorrow. Daddy needed a nap...

 

 

 

Posted with Blogsy