February 28, 2014

CopterX 450 fixed and tested

I did get time to put together the CopterX 450 after the krasch. I had to replace the blades, the feathering shaft, main gear, boom and two servo horns. I used the RCX helical main drive as last time. I noticed that this specimen was not as good as the last one but good enough. I will probably use only Align main drive gears in the future.

February 26, 2014

CopterX 450 testflight and crash

I did my first test flight with the CopterX 450 DFC after changing ESC, motor and swashplate today. The blade tracking was completely off, since I haven't adjusted it since i changed the swashplate. Tried out some hovering anyway. It went fine until a servo horn broken and the machine came down a bit too fast.

Broken parts, after initial inspection:

  • One main blade
  • Feathering shaft
  • Tail boom
  • Main gear
  • The servo-horn to blame for everything
All in all it's not that bad. The snow probably saved most of the parts.

February 25, 2014

CopterX 450 motor and ESC upgrade

I had problems with the newly built CopterX 450 drawing a high current and the motor getting warm. I have now replaced the CopterX ESC and motor with a Turnigy Plush and Turnigy 3450kv motor. The plush is shorter but fatter than the original CopterX ESC and the canopy can't be mounted centered anymore. It is only a cosmetic issue.

I forgot to program the ESC before wiring everything and had to do the programming by transmitter stick. Took me a while before I realized I had to changed to throttle endpoints to the get ESC to recognize 100% thottle stick.

Gave it a blade-less spin in the floor and it behaved as expected. But the baby woke up.

February 23, 2014

3GX not fixed yet...

I thought yesterday that my problems with the tipping 3GX was a problem with the main blades. Todays test flight proved otherwise. The helicopter wanted to tilt to the right as soon as it started gaining some head speed.

I have upgraded the software from 2.1 to 4.0 in the 3GX and walked through the setup again. Tested to spool it up in the living room and it seemed more stable now. We'll have proof tomorrow if it works...

February 18, 2014

New setup on 3GX on 250?

The plan for tonight was to finally fix what seemed to be a bad setup of the 3GX in my Align 250. I had troubles with the machine last summer as it tilted violently forward during spool up. However, the problem was not that hard to fix.

To prepare for the 3GX setup I started to remove the main blades. At this point I noticed that they were not very tightly fitted, at all. I built the machine some time back and I can't remember if I did anything to properly lock down the main blade screws. The screws on the 250 DFC does not have lock-nuts but are instead screwed into the threaded lower part of the blade grip and there is nothing to lock it into place.

Now it has some locktite applied and I tested to hover the machine indoors, which seems to work fine. Onto to the next maintenance project...

Tri-copter build and first flight

I have since the last post managed to put together the tri-copter, fly it indoors, crash it outdoors, re-flashed it with the wrong firmware and put it up on the wall.

The assembly of the booms with ESCs and motors took some time. I re-built the tail after realizing the the capacitor on the ESC might touch one of the tail mounting bolts which could result in a short circuit. It took it apart and insulated it. The slots for passing the motor leads out of the boom were not hard to cut, but hard to get a good look. Mine does not...
I should have used shorter servo lead extensions, maybe 15cm (maybe even 10cm) instead of the 45cm I use, they take up a lot of space and cause a lot of ugliness. On the last two booms I applied a bead of hot glue to the connectors to avoid them from slipping if you accidentally tug on them during assembly.

The X900 has no form of power distribution built-in. I soldered the three pairs of ESC power cables together with the BEC supply cable to a 12AWG (very oversized) battery cables. An E-FuelGauge is also attached to the battery cable. I use EC3 connectors to the battery.

The long servo leads cause a big ugly bundle of cables attached to the body. But this is nothing to the bundle caused by the S-BUS decoder. I use a Corona decoder, which has long leads both for the inputs and outputs.

My KK 2.1 board does not feed +5V to the servo connectors, which I find a bit strange but for a quad+ multi-rotor it isn't needed. The tri-copter however has a servo connected to the servo output, and gets no power! I made a split on the power lead from the BEC and needed to use a Y-harness to plug power in through one of the input-connectors together with the channel. Truly a big mess!

After having spent some time fixing the power supply pitfalls I finally tested it indoors with FPV gear mounted and the googles on my wife. Worked fine!

The other day I flew it outdoors. It flew fine until one of the props came off. No greater damage seems to have occured. However, I got really tired of the ugly bundle of cables because of the S-BUS decoder and I misread an announcement from RC911 concerning a new release of the KK2.1++ firmware. I thougt it was for the S-BUS version. It wasn't. The device is already re-flashed and cables removed. I think I will wait a while and hope RC911 comes up with a S-BUS firmware for the KK2.1.

Until them, I've made a simple wall mount to get it away from the workshop to move on with other projects. Waiting in line is a reconfiguration of a 250 with 3GX, repairs of an EDF and installation of an E-fuelguage and CGY750 in a 550.

Seriously HobbyKing!

I ordered a few parts from HobbyKing a few days back, mainly a fatshark camera and a 450 tail rotor set. I just got the shipping notice and the tracking number from them. And this time they are sending my package via Fiji. FIJI? Does HongKong post really hate you that much after the LiPo issues? Normally I calculate about 3 weeks delivery time with HobbyKing, but this time its going to take a lot longer I suspect.

And seriously HobbyKing? How hard can it be to focus on the one thing you're doing rally great, namely bringing low price product to the modeling hobby? Why do you need to promote sexism? Do you really think it will bring you more customers? I doubt it's the marketing staff that has come up with this idea.

I personally think that sexism has nothing to do with modeling or any other hobby for that matter. For those who want to see naked ladies, please go to google.com instead of hobbyking.com.

Get it together already hobbyking!

February 5, 2014

Tri-copter tail build, first attempt

Yesterday I started building the X900 tricopter. I started out with the tail boom and electronics. The power-leads to the ESCs needs to be extended by about 30cm and the motor connecters changed to the 2mm connector of the ESC. A bigger connector could be used but the ESC is only rated at 20A because of the connector and a bigger connector would make installation of the ESC into the boom difficult.

To install the ESC (plus servo and LED-cables) into the boom you need to cut a slot into one of the booms sides. This is because the outer end of the tail boom is blocked by the yaw-mechanism and there are three screws traversing the boom. The innermost screw holds the landing gear in place and determines the outermost position of the ESC (because of the big capacitor). Because of this limitation, the motor wires and/or the ESC wires are about 3mm too short. I discovered this too late.

My choice of servo (BMS 385DMAX) does not fit into the servo holder. Nothing a bit of filing won't fix. Also, it cannot be installed with the rubber dampers. This makes it impossible to install the lower connecting bolt which holds the servo-mount steadily together.

Today. I will take apart the tail assembly to extend the motor wires, apply some insulation to the ESC capacitor which might touch the landing gear screw and remount the servo to make the connecting bolt fit.

February 3, 2014

Missing 450 parts, let's start on the X900

I got some spare time today to continue to 450 scrap build. But after putting together the top and bottom body halves and adjusting the gyro settings I quickly realized that the tail hub I had planned to use is not in a good condition. I used that hub previously and the helicopter flew very good (until I crashed it). The tail was not affected by the crash but when I looked at it today I decided it's a no-go. I'll have to order a new one and the build is probably shelved for another three weeks.

What to do now? I have a second hand FPV kit on the way and no multi-copter to put it on. So I used the few minutes I had to get started with the X900 which has been in its box for a while. And most importantly, I recently got the ESCs, reciever and e-fuelgauge for it and motors, controller and sbus decoder arrives tomorrow.

X900 PartsHere's a part overview. The larger parts give a good impression. Quality seems higher that T-Rex clone parts from hobbyking (which I have a lot of experience with). Both the glass fiber cut outs and the  booms looks well made. However the screws and the ball caps looks less well.

X900 minor assembliesI've only put together the minor parts so far. I'll wait until I have connectors, wires and servo leads ready on the ESCs before putting everything together. The parts fit well but I already realise that putting the ESCs in the booms might become an issue.

On the image I've added the Afro slim for reference. How did the designer of this package think? Ok, the board layout make is fit well in the boom. But they knew which length of booms this would probably go into. Now, the servo lead is longer than the power cables, but not even those are long enough! Secondly, the boom will have no less than five screws/bolts traversing it, four verical and one horizontal. I'm considering not placing the cables through the ends on the boom and drill holes on their sides instead. But how till this affect stability?

This machine will get the name "stab-copter" which one of my colleges exclaimed when seeing the design of the landing gears.

February 2, 2014

Second Bixler aileron fix

My previous fix of the broken Bixler aileron was not so much of a success. Turns out the tape I was using is really sticky and sticks really well to anything, except itself. Hence, the temporary hinges formed by the tape disolved after a few days. But I got some hinges to try out in the mail the other day and now I fixed the aileron a second time.

I used a simple pinned hinge from HobbyKing. Its fairly small and I don't think it is meant to screwed on. I mounted it by cutting a fine slot in the foam, applying a drop of CA and pushing it into place. This makes for a almost hidden hinge and in seems to be working fine. I used three hinges to avoid flex in the center of the aileron.