Quadrysteria Mini Mamba Review

Mini Mamba (Final Version)

A while back, I bought a 250 racer style kit from Quadrysteria called the Mini Mamba.  It is high quality in general, with Sunnysky motors, true carbon fiber frame, SimonK ESCs, etc.  The kit included the frame, motors, ESC, integrated BEC/power distribution card, and instructions.

I initially elected to use a Mobius FPV system, spare mini-APM controller, and Lemon DSMX receiver to complete the build.  I started trying to use the instructions, which are well written, but not very useful.  Unfortunately, there are no pictures and you are left wondering which plate is the top, what is the front, exactly what standoff is required etc.  Fortunately, there are video instructions here, and they show you exactly what to do.

In the initial build, I ran into a few problems, some of my own making.

1. The mini APM may have been defective, it did not consistently stabilize the unit.
2. The integrated power board from the kit was defective.  It did not supply proper 5V for the receiver and APM.  I had to replace it with a power distribution board and use one of the ESC BECs.
3. The wiring for the mini-APM and rest of the electronics was not reliable, probably due to the crummy wiring supplied with the mini APM.  The ESC BEC was probably not the best choice as well.

The Mamba flew, but not well, I did crash it badly enough that I had to repair it.  One of the advantages of the Mamba is that will usually just break the props and/or the nylon bolts that hold the motor mounts to the carbon fiber arms, and this is easy to repair.  Previous quads tended to break arms, props, and frame plates, necessitating major repairs that takes hours and hours.

Based on this experience,  I stripped it down and rebuilt it with an Orange receiver that I had used before, a separate BEC, and a Hobbyking mini APM and Hobbyking GPS.  The wiring was much more straightforward as the Hobbyking units came with better cables and I was using a separate BEC. It takes some work to figure out where to stick the ESCs, cabling, BEC between the top and bottom plates.

Side view

Performance is much better but there is still a lot of tuning required as it is very sensitive to pitch and roll, but very insensitive to throttle.  Some other pictures are shown below.

Arm assembly which is set up for easy repair after crashes

Mobius FPV setup with integrated mount and transmitter.  This will be reviewed in future.

Converting the Eachine Racer 250 to APM Controller

A while back I wrote about buying the Eachine Racer 250, which used a CC3d controller.  Well I got tired of trying to figure out this controller and decided to switch the controller over to an APM.  I used the Hobbyking Micro APM, but you can get the same hardware from Banggood.

This started out easily enough, but there were a few hurdles along the way.

Step 1 Disassemble the Eachine

Take the top deck and battery alignment plates off as shown in the figure 1.  Be careful when removing the power connector for the 5.8 GHz video transmitter as it can be easily damaged.  Use an old coffee cup to store the parts while you work on the rest of the project.

Figure 1

Step 2 Mount the Micro APM

The Micro APM will easily go into the CC3D mounting standoffs as shown in figure 2.  Note that you will have to remove one standoff that supports the battery alignment plate as it blocks the USB port.  Figure 3 shows the APM mounted from the top

Figure 2

Figure 3

Step 4 Wire Up the APM

Here is where it gets a little tricky.  The servo wiring from the APM to the receiver is done as per normal.  The Ardupilot.com website shows how it needs to be done.  This is easy.

Next, you need to supply power to the APM so you will need to make up a cable that goes from the Eachine 5V and ground power pads (green arrow Figure 4) to the power input connector of your APM (magenta arrow, Figure 4). You will need a 6 pin connector to attach to the APM.

Then, we come to the tricky part.  The connections to the motor speed controls are shown by the red arrow in Figure 4.  You have to make a new cable here.  The motor numbering IS NOT THE SAME for APM and CC3D.  The cable will need to be set up as follows:

APM            Eachine

5V                5V

Gnd              Gnd

Motor 1        Motor 2

Motor 2        Motor 4

Motor 3        Motor 1

Motor 4        Motor 3

Figure 4

Step 5 Reaasemble the Eachine

Now you can reassemble the battery alignment plate, top deck, and secure any loose wires.  You are ready to fly again after the usual ESC calibration, radio, compass, gyro calibration are done.

Figure 5 Reassembled Eachine Racer 250

Quanum Q-2D Brushless GoPro 3 Gimbal Test

Gimbal Mounted on S500 Quadcopter

Attached a 2D camera gimbal to the drone and did a quick test flight with my Gopro Hero3+ Black.

The included Gimbal mount on the S500 frame was not useable as there was only about 1-2 cm of clearance between the bottom of the gimbal and the ground and I was sure that the gimbal would be damaged in a hard landing (see previous review of the S500 frame).

The gimbal is the HobbyKing Quanum Q-2D Brushless GoPro 3 Gimbal.  I could not get it to work attaching the gimbal controls to the Pixhawk so I connected the servo cables to the FlySky i10 receiver directly.  The only adjustment was limiting the maximum throw on the transmitter for the gimbal controls to +/- 30%.  This makes the gimbal less sensitive to the movement of the rotary controls on the transmitter.

Successful indoor Test Flight is shown below:

Unsuccessful outdoor test flight (gimbal worked, quadcopter not so much) is also below:

Hobbyking S500 Frame Review

S500 Quadcopter

I am building a new quadcopter for higher quality photography using the hobbyking s500 frame, which is similar to the sk450, but slightly larger.  It is now flying and I can comment on its pros and cons.

Pro

• Slightly stiffer arms than Sk450
• Plenty of space for electronics
• Higher landing gear to allow for camera gimbal
• Adjustable mount for gimbal - can shift gimbal forward and backward 
• Integrated pcb for power distribution 
• Spare parts available
• Low cost 

Con

• Landing gear not too sturdy 
• Landing gear too low to use included adjustable mount with 2 axis gimbal, have to hard mount to pcb

Note Top of Landing Gear, too flexible, not well attached to frame

I used sunnysky 2212 motors and they are much better than the turnigy motors on the SK450 - powerful, quiet, less vibration, smaller. I was also able to use my pixhawk controller which would not interface properly to the turnigy plush ESCs when I tried it on the SK450. For the S500 build, I used low cost Spider ESCs with SimonK firmware, which worked well with the pixhawk. Carbon fiber props and the previously reviewed Flysky i10 radio rounded out the build. 

First outdoor test flight is shown below. 

Summary 

The S500 is a good frame for a camera quadcopter, but it is not recommended for a beginner builder. Modifications are needed for camera mounting, the landing gear, and perhaps for power wiring so it helps if you have some experience with building  quads. 

S500 fully assembled with Gimbal, Telemetry

Pixhawk Versus APM Comparison Review

This blog entry compares two flight controllers from the Ardupilot 3DR-Open-Source stream: the generic APM 2.X controller and the Pixhawk.  I am an intermediate multirotor builder and flyer, so this comparison will focus on functionality and useability, not on advanced features.  Also, this review is based on my experience with 5 different APM modules (none sourced from 3DR) in three different physical forms: standard, mini, and micro (also called mini by some) sourced from Hobbyking and generic Chinese manufacturers.  The Pixhawk is available from multiple domestic and Chinese sources and you should check the reviews to make sure you are getting one with decent build quality.  Each was used with corresponding GPS/Compass units from the same manufacturers.  I built three different quadcopters and used them with different controllers.

Feature/Characteristic	Generic APM 2.X	3DR Pixhawk	Comment
Size/Weight	Small	Larger	APM is available in 35x35x5 mm board.  Pixhawk is 81x50x16 mm
Cost	Low	Higher, about 4X	APM with GPS ~$65
Quality	Variable	Better	Inspect a generic APM after you get it for poor soldering, loose USB..
Support	Good	Good	The best support is from peers on DIYdrones and APM forums
Flight Stability	Good	Good	This is my experience with a well setup APM and Pixhawk, your experience may vary
Accuracy	Good	Better	It does depend on your GPS and its accuracy.  Pixhawk has a more powerful processor and more memory
Onboard indicators	Poor	Good	Pixhawk has multiple LEDs and tones to tell you status, APM has a few LEDs
Ease of Setup	Moderate	Moderate	More components to interconnect on Pixhawk, but well documented. Cables and connectors often an issue with APM and documentation must be found on the Internet.
Ability to fly autonomous missions	Yes	Yes
Mission Planner Ground Station Compatibility	Yes	Yes
Flight logging Capability	Good	Better	Pixhawk logs more information and has a microSD for storage. APM has limited storage of most important variables.
Upgradeability	None	Yes	APM code is now frozen to my knowledge, but Pixhawk software with improvements still being released
Debugging difficulty	Good	More difficult	APMs seem to always work, Pixhawk is more finicky about ESCs, setup, etc.

Overall, both controllers are excellent and have worked well for me.  The APM is a better fit for small quadcopters and is probably better for the beginner builder due to its simpler setup and low cost.  The Pixhawk is very good but it takes more time to set up and it is likely higher quality and performance, so it works well in larger camera quadcopters and similar expensive vehicles.

APM equipped SK450 "Dead Cat" Quadcopter

S500 Quadcopter with Pixhawk

Further Enhancements

After the exciting flight last week, I had to repair the Quadcopter as one of the arms broke in a landing.  So I decide to make a few enhancements:

1. Put in a new APM controller and GPS to fix the Loiter issue.  This did not turn out well as the new controller was defective but the GPS seemed to improve things.  The new GPS is Hobbyking brand, old one was a "no-name" with some mods to make the cable work.
2. Improve power feed to the controller and receiver by using a UBEC (battery eliminator) instead of the power feed from the ESCs.  This is recommended due to the interference from the ESC and I do think  it improved things.
3. Get rid of extra wires in the controller wiring harness.  Done.
4. Install new arm.  Did this, I learned from the dearly departed Flying Flowerpot quadcopter that it is almost impossible to properly fix a quad's arm and they are reasonably cheap.
5. Performed a test flight and analyzed logs.  Seemed to improve things with few glitches on barometer and GPS and more stable flight.  Testing will continue.

Quanum FPVplus Wide-Angle 1080P HD FPV Camera with 5.8GHz Transmitter Review

I recently purchased this camera from Hobbyking with the intent of using it for video recording on my quadcopter and perhaps FPV operation.  The camera takes still photos, videos, and real time video and incorporates a transmitter so you can use it for FPV flying.  It is an integrated alternative to using an FPV camera and separate 5.8 GHz transmitter and it follows the GoPro form factor to a large extent.

After some use, here are my views on this product.

Positives

1. It uses the Gopro form factor, so it can use Gopro accessories.  It is lightweight.
2. You need to do some work to adapt this to your quadcopter:
1. You have to adapt the supplied cable to provide a 12V supply to the camera.  It has no internal battery so it is useless without power.
2. It has no included mount or tripod threaded hole so you need to adapt a Gopro mount to your purpose.  This can be done with the usual hobby tools.
3. The video is of acceptable quality, quite good in fact, see the video sample below.  This was taken with no gimbal, a shock absorbing mount, and reasonably balanced props, so it still has some shake.
4. Construction seems rugged.
5. With the included transmitter and antenna, it is easy to set up for FPV operation.  I was able to connect the camera to my RX LCD5802 7 inch monitor in about 5 seconds - truly easy.
6. Downloading the videos to a Mac or PC is easy using the microSD card.  Note that the camera will not work without a card.  Also note that the developers seem to have used Huawei phone software as the base for this product - you will see some directories and files that are unusual for a standard digital camera.
7. I recommend always connecting the antenna when the camera is powered up.  Some RF transmitters can burn out if they have no load like an antenna.  Don't know if that is the case here, but better safe than sorry.

Negatives

1. It is difficult to know what mode the camera is in as there is no LCD display and only one LED to provide status.  Spend some time with the very brief instructions on your workbench to familiarize yourself with operation before flying.  Otherwise, you may take off with the camera turned off.
2. The MicroSD card sticks out and can be easily ejected.  You may want to put some tape over it temporarily so you don't eject it at an inopportune time.  You also need to consider this when you adapt the camera to a Gopro accessory.
3. You cannot adapt an onscreen display (OSD) to show quadcopter telemetry on your ground screen as the video to transmitter inteface is within the camera and cannot be accessed to insert an OSD card between camera and transmitter.

In summary, I recommend this camera as a simple to set up FPV camera and transmitter system for quadcopters and other UAV.  It is easy to set up, provides good video, and is rugged.

Rear View

Side View with antenna removed

Side view with MicroSD slot, mode switch, connector

Gopro mount modified to accomodate antenna, cable, switch, etc.

Back Up and Running

My Deadcat SK450 is back running and as well as ever, the youtbe proof is above.  The modifications I made:

1. Replaced 3DR Pixhawk and GPS with Hobbyking Micro APM and no-name GPS.
2. Removed 3DR power monitoring module.
3. Used Spektrum DX6i radio and DX610 receiver.
4. New landing gear shock absorbers (see picture).

The finished unit is shown below:

Reconstructed Quad

The other mods are shown in the following pictures:

Putting Pixhawk aside

Micro APM mounted on standoffs on plywood base

Wider view

After many days of debugging Pixhawk problems with ESC calibration, channel mapping, poor stability.. I put it aside and went back to an APM 2.7 unit for the SK450 dead cat.  The pixhawk seems like a nice unit, but the factory support was mediocre, the warranty is 3 months, and it seems pretty finnicky about ESCs, powering, and such.  Online support from forums is usually helpful but not always and not in this case.

Removing the Pixhawk was reasonably easy but the APM was a pain as it is a micro unit and is not nicely packaged.  I mounted it on standoffs as shown and replaced the GPS with a known good unit as well, let's see what happens.

Deadcat SK450 Test Flight

New Quadcopter Build: SK450 Dead Cat

Now that we are back from Florida and parts have arrived, it is time to start the new build.  I salvaged whatever I could from the Flying Flowerpot (may it rest in peace).  Two motors, the four speed controls, battery, flight control, receiver, and camera were all salvageable.  However, I decided to replace some of these parts and to change the configuration of the quadcopter to "Dead Cat" - a non-square quad setup with more room for cameras.  See the picture below for the basic setup, not fully assembled.

The other changes that I plan to make are:

• New flight control system (Pixhawk) with more accurate GPS (LEA-6H).  I bought the genuine 3DR versions instead of the Chinese clones to ensure quality.  My old APM 2.6 system was a Chinese clone and had limitations and unknown quality.
• New receiver (Spektrum AR610).  This receiver is highly regarded compared to the Orange R615X, which has rumors of range issues.  New Spektrum DX6i transmitter.
• Use of a PCB as a frame to distribute battery power, bought from Hobbyking.
• Dead Cat configuration using a conversion kit from Hobbyking.  I made a mistake and assumed that all I needed was the previously mentioned SK450 Dead Cat PCB, but it turns out that you need this plus the Dead Cat conversion kit.
• Full monitoring of power by the control system.  This was included with the Pixhawk.
• A proper cover instead of a flower pot, sourced from Quadrysteria.com.
• Receiver power from the Pixhawk or separate UBEC, not from the ESC's.  This should be higher quality power with less interference.
• Use of loctite on all screws to reduce the chance of loosening with vibration.
• Carbon fiber props.

The new control and radio system are shown below.

Evaluation of Homebuilt Quadcopter Components

I put together a table with my evaluation of the components I used to build the quadcopter and the rough cost of the quadcopter: $320.

Part	Source	Rating (1=best)	Approx cost	Comments
Hobbyking SK450 Glass Fiber Quadcopter Frame 450mm	Hobbyking	1	$20.00	Well documented, rugged
TURNIGY Plush 25amp Speed Controller	Hobbyking	1	$13.00	Well documented, works well, does not overheat, used 4
Turnigy Multistar 2216-800Kv 14Pole Multi-Rotor Outrunner	Hobbyking	1	$16.00	Works well, used 4 units
Hobby King Quadcopter Power Distribution Board	Hobbyking	2	$5.00	Works well but hard to mount
Extended Landing Skid Set for SK450 Quadcopter Frame	Hobbyking	2	$11.00	Works but a bit too flexible
Slow Fly Electric Prop 1045R SF	Hobbyking	3	$3.00	Works, inexpensive, but prone to breakage
TURNIGY BESC Programming Card	Hobbyking	1	$5.00	Well documented, works well
Turnigy 2200mAh 3S 20C Lipo Pack	Hobbyking	1	$10.00	Good power delivery, good value
OrangeRx R615X DSM2/DSMX Compatible 6Ch 2.4GHz Receiver w/CPPM	Hobbyking	1	$10.00	Works well, good value, compatible with Spektrum DX4i Transmitter
HobbyKing HKPilot Mega Mini Combo Flight Controller GPS and Power Module	Hobbyking	4	$120.00	Flimsy USB, poor documentation
5" (inch) Travel Micro USB Cable, Twin Pack Cables	Amazon	1	$10.00	Great way to protect USB on APM
Hobbypower Top Pin APM2.6 External Compass APM Flight Controller w/ UBLOX NEO-6M GPS	Amazon	2	$70.00	Works great, great value, no documentation
Tenergy 1-4 Cells Li-PO/Li-Fe Balance Airsoft Battery Charger	Amazon	1	$20.00	works great, great value
2 of NEEWER® 3.5mm Gold Plated Bullet Banana Plug Connector for RC Battery 10-Pairs	Amazon	1	$7.00	Works well, used 2 packs
Dowels, screws, glue, velcro, flower pot	Home Depot	1	$25.00	Cheaper than hobby store
Total cost of built unit (not including broken Hobbyking Controller)			$319.00

Lessons from First Quadcopter Build

I learned a few things from building my first quadcopter drone.

1. The USB port is very fragile, attach a permanent short extender cable to connect to your PC.  Otherwise, you will be buying a new controller.
2. You need to take time to think as you assemble the drone.  There are lots of ways of attaching components and taking some time to think will yield a better result.  Spending time with the Mission Controller application will help you set up your drone, understand how it will work, and allow you to test some of the functions before flying.
3. The best places to get pieces are online stores like Amazon and Hobbyking, Home Depot, and your local hobby shop.
4. Nylon cable ties are a great way to attach things to the quadcopter frame.  Why use bolts when a simple tie will do?
5. Learn how the controller works before flying.  There are some modes like "althold" that sound useful but should only be triggered after flying.
6. Make a tethered test setup to test fly your quad.
7. Use the Wiki, google, youtube, and manufacturers sites to find solutions to problems or helpful tutorials.
8. Get a good soldering iron and learn to solder.

Building Quadcopter Part 7 - &%$#*

Stuff goes wrong when you are building a model, at least it does for me.  Today, I connected up the receiver, controller, speed controls and interfaced to Mission Planner on my PC.  Mission Planner allows you to set up your quadcopter, calibrate sensors, and make flight plans.  My goal was just to do the set up and see how calibration works.

Two problems:

1. The speed controls did not seem to inteface to the flight controller - they delivered no power.  Need to check this out.
2. As I was calibrating the compass with the USB cable installed, the connector broke off the controller card (see photos above).  It looks like this is a common problem - the connector is definitely flimsy.  The calibration processs has you waving the quadcopter around with the cable attached and it put too much strain on the surface mount solder joints on the board and pop.  My attempts at repair using the original connector were unsuccessful.

Now I have to wait for a new connector and see if I can repair it, which does not look easy given the tiny dimensions of the connector.  I also ordered a backup controller in case I cannot repair the old one.  Lots of swearing and frustration and it will probably be at least a week before I am back up and running.

Building Quadcopter Part 6

Photo 1: ESC (speed control) and motor mounting

Photo 2: More detail on the ESC and motor

Continuing with the build, I attached bullet connectors to the Turnigy 25A Plush speed controls (ESC) using the soldering technique mentioned in the previous blog entry.  The motor leads were shortened to 2 cm to make the wiring tidy and to reduce latency.  I then used heat shrink to insulate the bullet connectors.  The Turnigy Multistar 2216 motors were also mounted on the frame.  The speed controls are connected to the motors under the frame arms and the connections to the power distribution panel are also underneath.  This is shown in Photo 1 and 2 above.

Building Quadcopter Part 4

Continuing the build.  I mounted the power distribution panel on the bottom level as shown in photo 1.  It is a Hobbyking part that connects the battery up to the 4 speed controls.  The only problem is that you cannot use the current sensor that came with the controller package, but that is OK for now.

Photo 1 Power distribution

I also found a reasonable guide to the software to run the controller at this location.  Without this info, I was not able to find much useful info on how to load and set up the software on the flight conroller.

Photo 2 frame assembled

The frame is pretty much assembled as shown in Photo 2 and I have moved on to setting up some of the electronics wiring.  The video below was quite useful in helping learn the right technique for the Deans bullet connectors used in the power wiring.