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In case anyone is interested, here are some details to my latest Quadcopter build that is based on the open source MultiWii project. This one is slightly smaller than the X-8 described in my last build:

http://www.rc-cam.co...opter-build-log

It had its first flight today and flew well. For reference:

  • Weight: 24 oz without battery
  • Battery: 3S 2600mAH (Hyperion VX G3, 35C)
  • Motor Current: ~24A
  • Motor Watts: ~250
  • Props: 10 x 4.7

I'll also add some comments about the open source ER9X hacks that were done to the FlySky 2.4GHz transmitter that was purchased for this model. Spoiler alert: the ER9X software upgrade is awesome.

First, here's a size comparison photo of the new X-450 model with my X-8 (VC-550) and Gaui 330X-S. There's a distinct three bears thing going on here. :)

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Unlike a couple years ago, there now seems to be an endless variety of multi-rotor copter kits and accessories. Mostly from China shops. And more stuff appears every day. I closed my eyes, threw a dart on the wall, and selected a cheap fiberglass frame kit. The frame came directly from a China vendor; everything else was purchased from USA suppliers.

The frame is goodluckbuy.com's X450. It was only $25US (with a month long delivery) and seemed like a bargain. However, I ended up spending another $40 on hardware to make it flight worthy. Specifically, the single long boom arm that is shown in their kit's photo showed up as two regular arms. So if you build the model as-is there's too much flex in one axis. There's probably an endless way of fixing this; I added a VC-550 center plate from hoverthings.com, plus a bunch of spacers and screws from mcmaster.com. The plate helped make the frame very rigid and provides a larger area for the battery and Rx mounting. You can see the plate at the bottom of this photo (hint: the R/C Rx is on it).

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So a breakdown of the electro-mechanical parts is as follows:

Quadcopter Frame Kit: X450, goodluckbuy.com ($25)

Brushless motors: 2208x2208-17 Outrunner / 1100KV, 84hobby.com ($10 x 4)

Motor ESC, Exceed RC Proton 18A, hobbypartz.com ($15 x 4)

Frame Center Plate: VC550, hoverthings.com ($10)

Red and White LED strips, hobbypartz.com ($4 x 2)

Props: 10 x 4.7 (APC LP10047SFP and LP10047 ($3 x 4).

For the multiwii Arduino controller I randomly selected one from goodluckbuy. I did a web search and could not find anyone that talked about it (other than saying it was not a good deal), so ordering it was a leap of faith. It is a purpose made Arduino shield that has the CPU and the needed LLC (logic level convertor) with 2.2K I2C pullups (pullups choice is something other MWC's boards do badly). Plus it has all the connectors needed to support a basic Multiwii installation.

Here's a link: MWC Controller Board, $33

As luck would have it, the Arduino board worked out fine and is not a bad deal at all. It has a wide open area for the usual hacked WMP gyro sensor. But instead of the usual Wii sensor, I assembled another one of my custom designed 10DOF IMU-X boards (described in this post). It fit perfectly in the open area (as if it was made for it). It would have been lower cost to buy a similar ready-to-use sensor board, but I trusted the design and have a lot of spare PCB's.

Here's a photo of the MWC Arduino shield with the 10DOF IMU-X installed on it.

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So now some comments about the FlySky / ER9X conversion. Overall, a nice project for the serious / experienced R/C hacker. For beginners the stock radio is fine and the hack(s) should not be attempted without some hands-on help from a skilled electronics tech. First, here's a video of a pretty girl showing it off:

But like the six million dollar man, we can make it better, faster, stronger. That's the purpose of the ER9X project. And the reason for my interest in a cheap Chinese R/C system. Frankly, the open source ER9X project looked too interesting to pass up for a hacker like me.

My plan was to get the FlySky FS-TH9X ($89 US), install the FrySky 2-way telemetry kit, and flash the Tx with the ER9X software. I'm still waiting for the FrySky telemetry parts, so I've worked around that for now. Just so there's no confusion, FlySky and FrySky are NOT the same company. I guess the Chinese suppliers copy everything, including their own country's brand names.

I won't go into the details on how the ER9X firmware is installed. But to summarize the task, you open the Tx's case (6 screws), solder 6 tiny wires to delicate copper pads on the microcontroller's board, attach the wires to a low cost USB programmer, and then reflash the radio with custom code designed by very gifted programmers with a passion to make something better than intended. They are constantly adding new features too.

One very cool thing is that the new firmware is loaded into the Tx using a custom (and Free!) application called eePe. I was surprised by how professional and polished it looked. Besides performing the memory flashing, it also allows you to edit and back up your model settings. The user interface makes setting up new models a real joy. I did one model manually through the Tx's LCD and then another using the PC. The LCD interface works well, but it is tedious and slow going compared to the PC interface.

So far I have hacked the FlySky Tx with the required PC interface, added the haptic vibrator, and changed the beeper to a piezo speaker (for future wav audio support). Although I don't have the FrySky telemetry hardware yet, I'm running the software version for it. So far I like what I see.

.

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Just a couple of comments from my research:

Just so there's no confusion, FlySky and FrySky are NOT the same company.

It's FrSky, not FrySky. One more letter that is different at least if it serves anyone ;)

I won't go into the details on how the ER9X firmware is installed. But to summarize the task, you open the Tx's case (6 screws), solder 6 tiny wires to delicate copper pads on the microcontroller's board

There's another, much easier solution that's supposed to be suitable for pretty much anyone:

http://www.smartieparts.com/shop/index.php?main_page=product_info&cPath=3&products_id=331

It's a board that you just need to screw inside the transmitter, install the USB connector where you can reach it, and that has springs that directly make contact with all needed pads, thus requiring no soldering.

It's $45, but if you manage to get the $40 Turnigy version of the TX which is identical except for the grey case instead of black (The FlySky version seems to be running for about $110 at the lowest), you can get the board and still end cheaper.

I'm in your situation but the other way around, I have my FrSky equipment (currently one telemetry-enabled DIY module integrated in my Graupner MX16s TX and 7 receivers, waiting for an additional DHT-U integrated TX module and telemetry display for my Futaba T14MZ TX) but still waiting for the Turnigy TX (about 2-3 months backlog there apparently).

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It's FrSky, not FrySky. One more letter that is different at least if it serves anyone

Thanks for catching that. BTW, I've been told it's pronounced 'free-sky' so you would think they would spell it that way. :)

There's another, much easier solution that's supposed to be suitable for pretty much anyone:

http://www.smartiepa...products_id=331

It's a board that you just need to screw inside the transmitter, install the USB connector where you can reach it, and that has springs that directly make contact with all needed pads, thus requiring no soldering.

It was something I considered. But since I was going to hack a few other things in the Tx I decided to roll up my sleeves, warm up the soldering iron, and do it the manly way. :)

It's $45, but if you manage to get the $40 Turnigy version of the TX which is identical except for the grey case instead of black (The FlySky version seems to be running for about $110 at the lowest), you can get the board and still end cheaper.

For those folks (like me) in the USA, the HobbyKing shipping adds a lot to the overall cost. So the $89 FlySky from hobbypartz.com (with free shipping) is actually a reasonable deal. Plus, you will likely get it *much* sooner. Honestly, whether you pay $40 (+ shipping) or $90, it is a lot of radio for the price. :)

A few more comments about the stock FlySky TH9X system:

* The 8-Ch Rx that was bundled with the Tx does not have PPM-SUM.

* The 6-Ch Rx (R6B) I purchased has PPM-SUM on the battery port but is limited to 6 channels. I would have preferred at least 8. But since the FlySky Rx's won't work with the FrSky telemetry upgrade it's not a concern.

* I find the LCD hard to read. So the $5 back-light hack is next on the list of things to do.

I'm not sure if I will achieve 9-channels if I used the FrSky telemetry kit and the TH9X running on the ER9X code. The ER9X allows up to 16 PPM channels, but I don't know how many the FrSky upgrade will accommodate. I'll just have to wait until everything shows up and I try it out. So stay tuned...

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Still waiting for the FrSky parts. I ordered them from HobbyKing (before the China Spring Holiday) because they were the only supplier that advertised everything in stock. That was several weeks ago; I just received an email alert that claims the parcel has finally shipped. So I expect it will arrive in 2-3 weeks.

Today I wired up the X450's navigation lights and hacked the MWC software to control them with a spare R/C channel. Rather than duplicate the info, I've explained the LED control mod here:

http://www.multiwii....php?f=15&t=1198

BTW, that's one of the nice things about the open source multiwii project -- Adding a new software related feature is a matter of editing some files. :)

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For those folks (like me) in the USA, the HobbyKing shipping adds a lot to the overall cost. So the $89 FlySky from hobbypartz.com (with free shipping) is actually a reasonable deal.

Free shipping... OK, makes sense. For us here the choice is between $40 + shipping or $90 + same shipping, so well...

Still waiting for the FrSky parts. I ordered them from HobbyKing (before the China Spring Holiday) because they were the only supplier that advertised everything in stock. That was several weeks ago; I just received an email alert that claims the parcel has finally shipped. So I expect it will arrive in 2-3 weeks.

Yeah, nothing shipped during the holiday. I have 6 pending orders, just received shipping notification for one and from the status page the others should do the same soon.

BTW, that's one of the nice things about the open source multiwii project -- Adding a new software related feature is a matter of editing some files. :)

Yep it's great! When I made my first MK quad I screwed up and mounted the FC backwards on the frame... and as I had done things (too) well, I had cut all the wires to the exact length and would have had to replace the entire wiring to correct my mistake. ESC's were unreachable to change the addresses too. So I pulled up the code, swapped a couple of + and -'s, reflashed - done!

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I have 6 pending orders, just received shipping notification for one and from the status page the others should do the same soon.

Sounds like a familiar story. Hopefully all your stuff comes soon so I can use you for tech support. :)

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The FRSKY parts arrived today and now I have a FlySky Tx with telemetry. The installation took about four hours. I'll start up a new FrySky discussion and post some photos that shows a couple tricks I did on mine.

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This project deserves an update (should have posted it months ago). I flew the Goodluckbuy X450 frame for a couple months and I could never get it dialed-in the way I like it. So I moved the motors and electronics to a DJI 450 clone frame. The DJI frame is much more rigid which helps a lot. Although *everything* is the same except for the frame, the DJI 450 is night/day better (at least for me). It's interesting how things like this can make a big difference.

Details to the new build are here:

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I have just swapped out my FY90Q for a NAZA box and even without any adjustment it hovers better than the FY ever did. I cant wait for better weather so I can get out and test it properly :)

Terry

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I have just swapped out my FY90Q for a NAZA box and even without any adjustment it hovers better than the FY ever did.

I'd be very interested in hearing about how well its Alt-hold and RTH features work for you (two things I wish I had). So it would be awesome if you created a new topic about your NAZA experience; Classic show and tell. :)

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I recently upgraded my little GAUI 330X-S Quadcopter with a new flight controller and GPS (details are here: Click me!). That upgrade resulted in an awesome performance improvement and new GPS functions, so I decided to do the same makeover to the X-450. I finished the installation today and had a maiden flight. It flies well, but horrible altitude (baro) hold issues are preventing any chance of success with the GPS functions.

On the first flight with altitude hold engaged the model rocketed skyward then plummeted to the ground, and the wild yo-yo action repeated until I turned off the baro function. I have since reduced the PID settings which has eliminated this, but altitude hold remains unsuccessful. This behavior is nearly the same as I had with the old hardware and software. As time permits I will try more tweaks to the baro PIDs and will check for related problems such as vibration. I had been through this long before the upgrade and never achieved success, but I am hopeful I can solve it.

The upgraded hardware is very close to what was installed in the GAUI last month. As before, I used the Crius AIOP V2.0 ALL IN ONE PRO Flight Controller and XAircraft's Pilot Lamp module. But this time the Crius CN-06 GPS module was used (it has the ublox Neo 6M chip set). This module comes setup for ublox binary communication and is configured for 1Hz updates at 9600 Baud. I used ublox "u-center" PC application software to reconfigure it to send standard NMEA GGA & RMC sentences at 10Hz using 115K baud (a good match for MWC's V2.2 software).

Here is the GPS config file that was created and uploaded into the Crius GPS, a task that temporarily requires a USB TTL serial adapter:

NMEA_RMC-GGA_10HZ_WAAS.txt

By the way, the Crius GPS module appears to have more sensitivity than the GTop module that is in my other Quad. It has a slightly larger patch antenna and that allows the X-450 to see 7-8 satellites while indoors. The GAUI's smaller GPS module only sees 5 satellites while indoors. Outdoors they both typically get about 8 satellites. Because of the baro altitude problem I was not able to test the ublox's RTH (return to home) accuracy.

Here's a photo of the upgraded Quadcopter (click it for larger view). The new hardware fit without any issues (I only had to drill one new hole). Too bad the initial baro altitude hold performance is not working out as planned. If I can't solve it then I will probably use the big hammer fix and order a Naza controller.

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I did have some minor issues with my NAZA jumping a few feet for no apparent reason. When I sorted another issue with the YAW trim being way off centre due to bad props it cured both problems.

Terry

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Quote

When I sorted another issue with the YAW trim being way off centre due to bad props it cured both problems.

Good idea, I'll try a different set of balanced props. I've already checked to see if the altitude is being corrupted by vibration, but the baro data is rock steady throughout all throttle positions.

In between the rain storms I had a chance to continue tweaking the baro PID's. In calm conditions I'm now seeing altitude variations of about ±5 meters. I'm not satisfied with that. But the good news is that I was able to test out the GPS position-hold and return-to-home and (ignoring the altitude issues) both work well.

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Update: After a careful inspection of the props I decided to keep them. But they received a good cleaning and re-balancing. I also changed the rubber dampers on the flight control board's mounting screws. Now the altitude hold is about ±3 meters in calm conditions, which at this point is fine.

I think I could achieve slightly better performance if I experimented with the altitude PID settings, but I'd rather just fly the newly upgraded Quadcopter. BTW, I added some custom code that turns on the model's LED lighting strips whenever the GPS features are turned on; It will be easier to see when it decides to come home. :)

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I like the idea of the LEDs to tell you when its in GPS mode.

Terry

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I discovered that with a fully charged 3S LiPO battery that the voltage reported in the MWC's configuration app was much too low (11.4V instead of 12.6V). A bit of troubleshooting found that it was due to the VRef voltage used by the ADC in the Crius AOIP controller, which is only 4.5VDC. So the analog voltages that are measured must be below this reference.

But I'm using the default battery attenuator (51K / 33K resistors) suggested in the MWC project, which is scaled to provide 5.0VDC to the analog pin when the pack is fully charged. However this exceeds the 4.5V reference and causes the measured voltage to be wrong. Things are fine on battery voltages below 11.4VDC, so the MWC's low-battery alarm will still work as the pack discharges.

I could have ignored the fully charged pack's wrong voltage, but decided to fix it. I changed the voltage attenuator so that it's output voltage was 4.4V when the pack voltage was 12.6V (highest possible 3S voltage). The attenuator was buried deep in the Quadcopter's chassis, so I cheated and did the fix directly on the Crius controller by placing a 150K ohm resistor from the A0 analog port pin to ground. This is the same as changing the attenuator's 33K resistor to 27K ohms. A minor tweak to the VBATSCALE value in the config.h file provided a precise calibration and now all is dandy.

Long story short, if you are using the MWC project's recommended attenuator resistor values with the Crius AOIP then it would be wise to check the reported voltages to verify they are accurate as the battery discharges. If you are using their suggested attenuator values then it would be best to set VBATSCALE while testing a discharged pack rather than a charged pack.

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I could have ignored the fully charged pack's wrong voltage

Never! It would of been niggling somewhere at the back of your head just like it would me ;)

Tery

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