Frame Design

I got the desire to design my own frame.  I could have easily stuck with available frames out there especially cheap ones from Banggood.com.  I started doing research and learned that a company Armattan Productions will  take your design, cut it for you and send it.  They will even let you sell your design on their website.  And I've also seen videos on YouTube where all these FPV "Stars" design their own frames only to have it cloned a month later.  I'm going to be honest, frame design is no that expensive or difficult.

The first thing I did was download QCAD, which is a free program.  It is really simple to learn and use.  So without further ado here is my first frame:

The frame is designed to use a 20mm x 20mm stack (you can also use a 16x16 stack) which includes 4-in-1 ESC, F4 flight controller and a video transmitter.  It was also designed to use a micro fpv camera and tiny receiver.

The frame was designed to mount motors with a 12mm diameter mounting pattern such as the Emax RS1306.

As I was building it I realized that the ESC did not allow sufficient room for the camera to be mounted in the frame.  After doing some search I realized that there were multiply 3" frame designs that had the camera sticking out leaving it for the most part unprotected.  I decided to design a 3d printed camera and receiver mount for the top plate, this would have a bottom mount battery anyways. Here is the mount:

I wasn't too worried about the camera getting damaged by being mounted on the top because the quadcopter is so light that a crash will probably not do much if any damage.

The rest of the build went well.  I'll list all the parts below if your interested.

Here is a link to the first flight, turn your volume down: https://youtu.be/frVrTGhWT00

Here is a link to get your own: https://armattanproductions.com/pages/kit_detail/1652

Rotorbuild page: https://rotorbuilds.com/build/10667

I've flown about 6 batteries on this quad as of today and I must say it handles really well.  It also floats in the air for a few seconds when you let off throttle.  The stock Pids of betaflight 3.2.4 fly really smooth, I don't really see any additional tuning that would need to be done, maybe some small tweaks here and there as I fly it more.

Parts:
Growler Mini Bottom Plate: Link available later
Growler Mini Top Plate: Link available later
Emax RS1306 3300kv motors
HGLRC XJB F428-TX20 Omnibus F4 Flight Controller 28A 2-4S Blheli_S ESC 25/100/250mW Switchable VTX
FrSky R-XSR receiver
HGLRC XJB Elf Micro Camera
3d printed Camera and Receiver Holder: Link available later
some cheap props from Amazon

Fatshark Predator V2 VTX module replacement

Since the beginning I've been  flying FPV with the Fatshark Predator V2, this FPV goggle is not made any more and can only be found on Ebay for over $200.  These goggles were less than $200 brand new.  The receiver in this model is a single video receiver, this is two year old technology and in today's technological environment is considered too old.  

Today it is all about diversity, no I'm not talking about  people who are different than you, I'm talking about video diversity.  Video diversity is when your video receiver has the ability to switch between two antenna's picking the one with the strongest video signal (this may not be the most accurate explanation of how it works but I'm not an expert and this is how I explain it).  Video diversity means a more reliable video signal and less signal drop outs.  Diversity also allows you to run two types of antennas, an omni-directional for close range and a directional, helical or patch antenna for longer distances.

I purchased from Banggood the Eachine Pro58 as seen at this link: Eachine Pro58.  It is less than half the cost of the top performing diversity modules out there.  I decided to get this module because there is a firmware out there available from a guy in Europe called Achille, the Eachine module has a lot of capability and this firm ware increases the performance of the module by leaps and bounds.  The firmware can be found here: https://achillesfpv.eu/

In order to replace the module in the predator goggles I had to do some significant modifications which I will highlight below.  These mods are not difficult you just need to be competent at soldering.  Hopefully this post will help someone out in the future.

Photo of the predator V2 before disassembly.  I had previously installed the Attitude face plate and removed the eye cups, not a perfect fit but fits none the less.

Another view of the face plate installed on the goggles.  Was a much better fit than the stupid eye cups.

Removed the face plate, now just need to clean off all the hot glue.

Need to clean off the hot glue from the face plate as well.

Goggle cleaned off ready to disassemble.

Face plate cleaned off.

Only two screws holding the top and bottom plate together, these are located on the bottom.  View of the goggles just opened, photo was also used for reference when putting it back together.

View of the stock VTX

I cut all the pins seen in the photo above.  Removed all the black plastic around the pins then used the soldering iron on the bottom side of the board to heat up each pin and push it flush with the board.  I then used needle nose pliers to grab the top of the pin and while holding the board up by the pin, placed the tip of the soldering iron against the side of the pin causing it to heat up, liquefy the solder and with the weight of the board pulling down the pin would come out of the hole.  My only concern working with this board was getting the solder holes too hot causing them to come off the board so I avoided direct heat to the holes as much as possible.

I then soldered wires with servo connectors to each of the pins.  Don't worry about wire color or anything like that, the pins on the main board line up directly with the pins on the module so you don't need to worry about which pin is which, just connect them like this, top on board to top on module, 2nd one down on board to 2nd one down on module going all the way down in order.

I then had to cut both the top and bottom of the case with my dremel and cut off wheel to fit the servo connectors seen in the photo above.  The cut off wheel only melts the plastic but does a good job and after the plastic hardens a few seconds later it can be cleaned off easily.  I then attached the module with double sided tape and hot glue.  So this module is mounted on the outside....is it ideal?  No but it won't fit inside either so I had to make a choice.  You can't really see it any of the photos but the hole for the screw is between the two stock boards when you open it up.  Stuff on the back of the Eachine module makes it to where I couldn't get the pins to even touch the hole to solder them on.  I guess maybe there is a way, I could have looked at it more and messed with it more but I felt that this was the way I wanted to do it.  Another benefit to doing it this way is if I want to change modules again in the future it will be just a matter of unplugging this one and plugging in the new one.

Here is the module fully installed, just lacks a little bit of hot glue also.

I put the face plate back on and hot glued it in place.

Another view of the face plate.  I also had to take a permanent marker and color the glue because I was getting a little bit of light leakage on the top and bottom.

Well, that was it, I hope this helps some one.  I will be flying this weekend with the new module installed so I should be posting my initial thoughts sometime next week.

Thanks for reading, see you next time.

Turnigy 9xr Pro Gimbal Replacement

Well, I went and did it.  After 3d printing some gimbal covers for my transmitter (9xr Pro) I eventually dropped it on the floor and broke a gimbal.  I didn't notice at first that a gimbal was broken.  I found out the hard way.....trying to fly my quadcopter.  Control was so bad I performed a controlled crash ( I lost it ) into a bush, see video here: https://youtu.be/Q5FOA63PeVs

Hobby King used to offer replacement gimbals that would work in this transmitter, however they have been discontinued.  After some research I discovered that with some modifications the stock gimbals from a taranis will work.  This post is about my experience doing the mod and getting everything to work. 

I will post a series of photos that will show the work that was done and include the final product.

This is what the stock taranis gimbal looks like.

This is what the stock 9xr Pro gimbal looks like.  Notice the differences, location of screw holes and elevation of screw holes relative to the face of the gimbal.  This is where the modification will happen.

Stock gimbal still in place Mode 2 Throttle and Yaw gimbal

Stock gimbal still in place Mode 2 Pitch and Roll

The 9xr Pro gimbal screw holes are further apart than the taranis holes, hence the need to modify.  Cut the outer holes off the taranis gimbal on each corner

Grind down the top surface of each corner at the holes that are left.  There is what looks like two layers of plastic, you want to grind down the top layer completely.

This photo shows the top layer ground down to the second layer.  Second layer is hollow so you'll see it when you get to it

Another look at the first layer gone

The screw holes that are left are also too deep for the 9xr Pro screws and the ones that come with the gimbal are unusable so you have to cut some off the bottom of the screw hole or you can try and find longer ones, if you do you can skip to the bottom.  I cut mine even with the horizontal plastic that is between two screw holes on every side of the gimbal.

Here is another look, see the clean untouched plastic between the corners, that's the level you want to cut too.

Now you want to cut some of the screw hole out at about 45 degrees in each corner, don't cut out too much.

Pre-install the two screws near the center of the transmitter, these two are the most difficult to get in, leave enough height to slide the taranis gimbal underneath.

Now install the gimbal by sliding it underneath the two screws you just installed, add the two screws toward the outside of the case.  Once positioned the gimbal will be held in by the 4 screws however some may be halfway on depending how you position it.  This one appears to be completely in the hole which leaves the other side only about half way.  Either way once all the screws are tightened down they will hold and the gimbal will not move.

Photo of another mounting screw.

Photo of opposite side (pre-installed screw), see how the screw only makes use of half of the hole but the screw is still covering plastic holding in the gimbal

Now you will need to remove the wires from the 9xr Pro gimbals that you took out, need to reuse all four JST connectors.

Gimbal fully installed.  Notice colors of the wires on the taranis gimbal does not match up with the wire colors or order of the 9xr Pro gimbals.

Other side, the vertical wire group barely reaches, you'll need to break loose some of the yellow stuff covering the wires so that you can get the green harness where it needs to go also.

When it comes to the wire order, if the colors on your taranis gimbal are the same the order shown in these last two photos should work.

The three pins for the JST connector should read the following with a meter from left to right, 0v, +/- 0.5v, 3v.  If your sticks are reversed you will need to swap two of the wires, which ones I can't tell you it's just a matter of trial and error.  After you connect everything put the cover back on and plug in the battery, don't screw in the cover because if something is wrong you'll need to get back in their.

Turn on the radio, on the main screen you should see a depiction of two gimbals, move the sticks to confirm correct directions.  If all is correct, don't worry if the sticks don't show full movement on the screen.  Now hold down the menu button to bring up the options.  Go to radio set up and perform the calibration.  I recommend performing the calibration with the front chrome looking plastic cover on the front removed because the sticks will hit it in the corners.  Once calibration is complete and sticks move fine you can secure the covers.

You may also need to trim the chrome cover depending on how high the sticks go.  I had to trim two tabs around the opening for both sticks before putting it back on.

Good luck

ESC Electronic Speed Controller

The ESC controls what your motors do based on your commands from the transmitter. The speed controller essentially speeds up or slows down your motors allowing you to change directions.

The quadcopter kit I first purchased came with Emax SimonK ESC’s.  I don’t know enough about the esc’s to really say anything about them except that they work but they are crappy. There is a trick with SimonK, I attempted several times to calibrate them but couldn’t get it working, they just kept beeping.  I discovered through some research and some help from YouTube user Channy that from the time you plug in the battery during the calibration steps you have 2 seconds or less to lower the throttle in cleanflight.  It seems like a very short 2 seconds but nonetheless you have to be fast or you will go into programming mode on the ESC. My second quadcopter I upgraded to 20amp Blheli ESC's. Blheli is the firmware loaded on the ESC, it is much better than the SimonK firmware and much easier to update. The higher the amperage that your motors will draw will affect the size of ESC that you purchase. You can't go wrong if you just get 30 amp ESC's to begin with. On a racing drone you will not need higher than that.

I've ordered a new set of ESC's which are 28 amp, I will install those on my racing quadcopter and place my 20amp ESC's on a large aerial photography quadcopter that I am building.

Flight Controllers

Flight Controller

For the flight controller I first started out with an Emax Skyline32.  I purchased the Skyline32 because it came with cables and connectors so all you have to do is plug your receiver and ESC’s directly into the connectors, no soldering required.  However the problem with doing this is you get a very messy installation because the cables are so long.  After flying several times and slicing one of the wires with a blade during a crash I decided to shorten all the cables and just solder them together, this gave me the clean installation that I was originally looking for.  So the time and effort I wanted to save by purchasing this board backfired on me.  

I want to also talk about documentation.  For the most part documentation for flight controllers is seriously lacking in information. YouTube is your best resource for all flight controller information. The 14 page manual for this board gives you directions to go to three different websites to download some software in order to update the firmware.  After several hours of following the instructions to the letter, it did not work.  I finally found a youtube video by 2dogrc that shows him just flashing it with the latest Naze32 firmware.  I followed the video and it finally worked, I was able to get into cleanflight and get busy prepping my quad for flight.  My first flight with cleanflight was bad, the Quad flew like a cinderblock.  I discovered Betaflight and from the first flight it was magical.

Lesson learned: Go with an FC board that requires you to solder pins to it, having all the wires and connectors from the skyline32 makes for a messier installation, there was so much excess wire hidden away on my quad it wasn't funny.  Instead of having the servo connectors connected directly to the FC I installed all the header pins on my next flight controller a Naze32, everything is now plugged into the header pins. I still had excess wires to take care of so I wrapped them in heat shrink and tucked them away.  

I am now on my 3rd brand of flight controller, the Omnibus F3. I love this board, it comes with an SD card slot for built in black box logging. Built in OSD which allows you to access your important settings such as your PIDs and rates, I haven't been flying long enough to really notice a difference in performance but it is also only $25, no reason to pay more.

For a 250 quad you do not need a barometer, no reason to pay for the more expensive FC.  Betaflight is the way to go for firm ware.  From the first day I flew with it my quad flew really well, highly recommended.

Power Distribution Board (PDB)

In the beginning I purchased a Crazy pony PCB power distribution board for a QAV250 quad-copter.  The board did not come with any instructions.  I purchased the board so that I could achieve a clean and organized installation.  Without knowing any better I discovered that this power distribution board did not work for the Emax 250mm quad frame.  The reason why it did not work is because the board and frame are shaped differently, meaning the mounting holes do not line up.  Since I still wanted to use the power distribution board I ended up purchasing a YKS QAV250 carbon fiber frame.  This went together nicely with the power distribution board.  Any future builds I plan to use a PDB every time.

Lesson Learned:
Any PDB that is purchased must have a BEC or regulated power for 5v and 12v otherwise what's the point and don't get the type of PDB that is integral to the frame, I ruined the PDB for my QAV250 in a crash.

Your video transmitter and Camera will both need to be powered by clean regulated power or else your FPV system just won't work. I also learned the different frame names and types of styles. the QAV 250 is also known as the ZMR. Regardless of which manufacturer you get the frame from if it's a certain style, parts for that style should fit no matter what.

A power distribution board helps organize the installation, the biggest tip I can give you is to cut the wires to reach the solder pads on the board with just a little bit extra length so you don't leave yourself short for future work.

Quadcopter frame and kit

Starting with this post I will go over all the various parts needed to fly FPV. This post will be all about the frame.

I originally purchased the LHI Emax 250mm kit from Amazon, it was a good price and came with a full carbon fiber frame.  This frame is actually the same as the 250mm Emax Nighthawk, not a handsome looking frame but a spacious one nonetheless.  I also purchased a QAV250 frame.  Both frames are pure carbon fiber.  People make a big deal about the carbon fiber frames, I have yet to use a 3k carbon fiber frame so I don't really know if it matters.  As the title says I am a habitual crasher, in the process of learning to fly I have crashed my quad-copter on numerous occasions, some saw the death of components and various parts, some weren't too bad.  Some crashes were user error but some were also various malfunctions.  It's been a long road learning this hobby and learning the nuances of building and repairing. The most difficult thing to learn has just been the programming and setup, which now is pretty easy for me.

One time I broke the front arms of the QAV250 by crashing directly into some rocks.  I forgot that I was not in horizon mode.  This frame did not hold up well to that crash.  I haven't spent more than $30 on a frame. They are out there under that price and are full carbon fiber. They hold up well in minor crashes, however the weakest part of the frame is the aluminum stand offs. Top plates are usually held on by really short M3 screws. For my latest quad I went to the hardware store and bought screws that were twice as long as the stock screws. They appear to help better in crashes (yes I'm still crashing)

If you are a beginner you might consider a non-carbon fiber frame to begin with because it will be cheaper to replace if you break it. My brother has this type of frame that only cost him $13 on Hobby king. He has crashed into the side of a cliff and other crashes and it appears to have held up really well until recently. It finally broke on him. Of course he does not fly as often as I do, I try to fly every week. Hobby king had a deal where you could get two of these type of frames for $18 for both. I thought about getting it for a moment.

Lesson learned:  Start out with a cheap frame until you are a more confident pilot.  Spending $10 on a glass filled nylon frame that is durable yet cheap is perfectly fine for learning how to fly and learning FPV, you will crash, you will have to repair and rebuild....you just need to decide how much you want to spend on your rebuilding. I now fly with a full carbon fiber QAV210, the bottom plate and arms are one piece so it holds up better in crashes.

"We have the technology" - Six Million Dollar Man