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Posted by mike_kelly | Apr 07, 2016 @ 04:28 PM | 2,794 Views

Comparison attached as PDF at end, Compare_minis_3.pdf

It is very exciting to be at the beginning of a new technology. It is a time of great growth and new ideas but also a time of chaos.

I found myself needing to substitute one mini Pixhawk variation for another, in a finished build and started to check the pinouts of the similar connectors. I was surprised to find how different and impossible it was to substitute one for the other. I decided to survey the mini Pixhawk field and see just how different the cabling is between them, compared to the Gold standard of the original Pixhawk designed by Lorenz Meier (

I found out why it is so hard to simply get a GPS connected to a mini Pixhawk.

The industry desperately needs a 500lb Gorilla to come into the field and force everyone to conform to a standard so we can get rid of the ridiculous chaos.

I should make a comment about connectors here. The original Pixhawk used DF13 connectors and they have what I describe as a square hole as opposed to the similar Molex Picoblade which has slot like holes. The two can be interchanged but it is not a perfect fit. The last and most commonly used in the mini Pixhawk field is the JST-SH 1.0. It is noticeably smaller than the other two.

From left to right, the JST-SH 1.0, the Molex Picoblade, then the DF13.

...Continue Reading
Posted by mike_kelly | Feb 13, 2016 @ 10:27 AM | 2,192 Views
Posted by mike_kelly | Feb 05, 2016 @ 10:01 AM | 3,384 Views
The RC world has come a long way in the last few years due to the advent of flight control computers. The abilities and features of these boards have been improving and changing at a rapid rate. So much so that some flight controllers have become quickly obsolete because the boards ran out of room to store the programming on board or ran out of computing power to run the more sophisticated mathematics the allows smoother more reliable flight.

Case in point is the APM flight controller from the open source Ardupilot project. This 8 bit computer based flight computer was a great upgrade from it's arduino beginnings but as time passed and more features and improvements were added it began to be hard for the developers to fit their code on the board, constantly running out of room. The cpu just was not fast enough for the new mathematical routines that were needed.

...Continue Reading
Posted by mike_kelly | Jan 29, 2016 @ 10:41 AM | 3,539 Views

One of the more advanced aspects of RC flight is FPV. FPV stands for First Person Video and it means you are looking at a video display from a camera on the aircraft giving you the view that a pilot would have in the cockpit. This experience is as close to actually flying a plane as you can without leaving the ground. It is also a way to always fly with the orientation of the aircraft constant. That means that if the aircraft is flying away from you or towards you the aircraft right is always your right and aircraft left is always your left. Because it is like you are in the aircraft. One of the more difficulty aspects of normal RC line-of-sight (LOS) flying is that your orientation, relative to the aircraft, is always changing as you steer the aircraft. When you fly away from your self left is left and right is right but when you turn the aircraft around and fly back to yourself everything is reversed on the aircraft. In order to bank the aircraft right you need to use the left roll on your rc transmitter. It can be very confusing. But with FPV you can always maintain the same orientation with the aircraft.

There are challenges though. First you are looking at some kind of display. That might be a video screen or a pair of goggles. Either way it is a two dimensional image so you have no depth perception. It can be hard to tell how high you are or how close you are to objects.

When you fly LOS (line-of-sight) your frame of reference is the aircraft itself. When the...Continue Reading
Posted by mike_kelly | Dec 05, 2015 @ 08:40 AM | 4,742 Views
A reference for those looking for details. My scale may not be perfect but is seems to compare to claims well.

TL65B01 (650i ironman) claimed frame weight on the box=450g, my weight for the whole kit including plastic bags but not the spares =540g
Land Gear alone=100g

TL65S01 (650s sport)claimed frame weight on the box=750g, my weight for the whole kit including plastic bags but not the spares =755g
Retractable Land Gear and controller module alone=165g
Main PDB plate = 80g.
Arm Length 231mm

TL68C01(690)=claimed frame weight on box=600g, my weight for the whole kit including plastic bags but not the spares =765g
LG alone=115g
Main non-pdb plate = 45g
Arms fixed=323mm Folding=333mm

TL68P00(680Pro)=claimed frame weight on box=780g, my weight for the whole kit including plastic bags but not the spares =945g
Landing Gear alone=160g
Main PDB plate =85g
Arm Length 264mm
Posted by mike_kelly | Dec 05, 2015 @ 08:39 AM | 3,178 Views
I am going to reserve this page to introduce the people we have depended upon in the Ardupilot project. I am not an insider but I think it is important to start to learn about the project that we use and the people that make it happen. These are really smart really valuable contributors. Please post additions. These are only the people I have figured out are important assets in the project. In no particular order and forgive me if I am not aware of your contributions, information is very hard to find.

Lorenz Meier:

Swiss Federal Technical Institute of Technology, Department of Computer Science Computer Vision and Geometry Group
I'm working on mobile localization and 3D reconstruction on smartphones and micro air vehicles. I started my aerial robotics project, PIXHAWK, in 2009 as a master student. It is by now an on hardware autopilot anyone can use (open hardware website, research website). I participated in the sFly EU research project 2011-2012 and I'm currently mostly working on obstacle avoidance on drones, funded by a gift from Amazon Prime Air. I maintain in my spare time the open source and open hardware PX4 autopilot platform.
================================================== ==============================================
Craig Elder:

Craig has been managing the Ardupilot project for the past 4 years. Currently he is Technical Community Manager for Dronecode and former Director of Software Engineering for 3D Robotics. Reading
Posted by mike_kelly | Aug 07, 2015 @ 12:35 PM | 6,181 Views
ZMR250 Coaxial Octocopter

Now that I have a few builds under my belt, I did a review of what worked and did not work for me. When I first came to RC, with no experience whatsoever, I was surprised to see things used like the horrible Dupont servo connectors. They may have been simple and cheap in the beginnings of RC electric planes but they are really bad connectors for multirotors that vibrate and dive down through prop wash.

When I first started, I decided to do away with all those lousy connectors and such by soldering everything. Using connectors is notoriously unreliable. I produced a nice tidy build with every wire the right length, neat and tight by soldering. No cables 12" inches too long all folded up to stop them from tangling in the props.

Trouble is, the first time you crash and something fails inside the frame it can be a major major problem trying to repair it. Sometimes having to completely tear the build down to original parts to get at something.

I have been disappointed in the quality of the parts commonly used in RC but I should not really be surprised. The technology we use is absolutely amazing for the low price. A video transmitter for $30 or an autonomous flight controller for $100 is incredible. But the assembly and soldering are often poor, and the parts are probably "seconds" much of the time. I just have to live with it because I am clearly not going to pay the high cost of milspec parts which might cost 100 times more.

This...Continue Reading
Posted by mike_kelly | Jul 04, 2015 @ 12:14 PM | 6,134 Views

I'll say it right up front. I hate tablets. I don't like gestures and I miss my good old keyboard. The first tablet I bought had a resistive touch screen which was horrible. I found the early versions of Android to be buggy and unreliable.

So why did I get another tablet? I must have been tired late at night.

Or I heard the siren song of the foolish. $29 for a 7" Android tablet.

I bought a Maylong M-295 from Ebay:

I just knew I was going to be sorry.

But to my surprise this little tablet actually works. It is not the fastest thing in the electronics world but it is satisfactory. I needed to pause just a moment rather than zooming around. I found that it acts very strange when I ran the battery down too low, 10%. It comes setup for the Amazon App store so I had to figure out how to get Google Play Store. It just needs to be turned on in the Setup/Settings tool. It does not have a built in GPS.

Then I loaded Droidplanner 3 aka Tower and plugged in my old 3DR v1 telemetry radio and setup an APM board with the Air radio and it works!
Note here that no all tablets can supply power to the Telemetry radios so it is something to check before you buy. The feature is called "OTG" usb.

I have not actually flown with it yet but it talks to the APM just fine and I can change parameters. The HUD display reacts to movement of the APM.

I loaded Firefox from the Google Apps and a Navigation App called Maverick that will cache maps offline. I loaded VLC media player and it plays mp3 and avi movies just fine.

So I am impressed. If you have wanted to play with a tablet and Arducopter but been unwilling to spend the big bucks for a name brand tablet this unit might be worth a try. Who knows maybe I got the only good one in the universe and maybe it won't last a month before it breaks but so far so good.
Posted by mike_kelly | Jun 09, 2015 @ 08:36 PM | 35,449 Views
I just reviewed the Pixhawk LITE a low cost small form factor Pixhawk clone offering from GoodLuckBuy. It seems like it will serve well as a replacement for APM.

But for my big multicopters I am more and more looking for reliability. I have learned a few things from my first builds and the top three are:
1. The quality control on the common parts we buy is poor.
2. You are going to crash and break things.
3. Because of #1 & 2 you better be able to fix your aircraft without tearing it down to bare bones because you will be doing it often.

If you don't want to be frustrated think reliability from the start of your build.

That is where the Pixraptor comes in for me. You might think why do we need another Pixhawk clone, especially one that is more expensive than other clones? Well this new Pixraptor is not your take-a-picture-and- copy-it-exactly type board. Somebody really took a look at what could be improved and tried to make a better product. I won't know if they met those lofty goals until the build is finished but the attempt was definitely made.

First thing I notice is the connectors all come out the sides. I like this. It is hard to make a build with clean wiring if all the connectors are pointing straight up. Next they used molex connectors instead of Df13. Some people hate DF13 connectors. The deal is the DF13 connectors require you to tilt the connect on edge and kind of rotate into the socket. If you don't do that installing and removing you risk...Continue Reading
Posted by mike_kelly | May 20, 2015 @ 05:49 PM | 148,583 Views
************************ Notes or errors and omissions **************************
I started this thread a year ago. So be advised that although there is invaluable information in this thread the manufacturers can and have changed the product over time. Hence although I am not aware of it as of Jan 2016 they could someday fix the problems making the information here on page one obsolete. If you receive a board that does not seem to fit the data send me a PM and I'll update page one.

NOTE There was a version one of this board that had the power module pins backwards. You can not use a "normal"power module cable with that early version. The current verson GLB is calling V2. They fixed the power module connector. It now conforms to the Pixhawk standard. But all the other problems talked about below still exist.

Whomever created the pinout pictures on the GLB website got a number of things wrong, at least as of this date. Hopefully they will correct it.
The order of many of the pins are backwards from the same connectors on the 3DR Pixhawk. See the drawing labelled "corrected" for the actual pin-outs.

Since the I2C connector is backwards, but there is an expansion board for more than one I2C device, (I2C devices are compasses, LED external lights etc) jesmail suggests using a reverse cable from the Pixhawk LITE I2C port to the I2C expansion board. This has the effect of fixing the problem so all the devices you plug
...Continue Reading
Posted by mike_kelly | May 19, 2015 @ 08:38 PM | 7,338 Views
Tarot T shaped landing legs are pretty common throughout their line, as well as many other brands. Tarot uses hollow carbon tube skids. If you land at an angle and touchdown on only one of those legs first, they tend to break off right at the T joint. It seems like a pretty common problem. Some people put wooden dowels inside the carbon tubes but I did not want anything rattling around in my skids.

I first tried some fiberglass skids but I was concerned that with something much stronger it would just transfer the implact further up the landing gear. Sure enough the next flight with the fiberglass skids I did not break the skid but instead broke the T Joint and the landing leg and the attachment at the top for the landing leg.

Not a good trade-off.

Then I found some nylon 10mm rod on Ebay. It comes in just about the right length. It bends, unlike the fiber glass and will absorb some shock. I dont know if it will be enough but time will tell. It flexes under stress but is not too soft.

If you have a better idea please post a comment, thanks.
Posted by mike_kelly | Apr 13, 2015 @ 11:22 AM | 8,839 Views
************************** Mis-labelling *******************************
I think I have figured out what is wrong. THESE ARE LABELLED WRONG!! I am so tired of products with sloppy incorrect documentation. On each quick detach is an arrow, which you might reasonably assume indicates the direction of the motor they are designed to go onto. Nope the labels are backwards and the description is backwards.

In most ads the TL68B36 is described as a ccw and the photos have an arrow in the ccw direction. My Tarot prop adapters that are labelled as such go on the CLOCKWISE motors NOT on the ccw, in order to work correctly i.e. not spin off during flight.

Please see Post#59 at

Originally Posted by strips View Post
Unless you have a genuine foxtech prop mounts I would not trust the colour to be enough. Hold the prop and rotate the motor the way it would rotate when flying. It should fasten the prop.
Agreed - THIS IS THE ONLY SAFE WAY to proceed - with several different suppliers now selling these adapters in different colours - please do it the way suggested above by "strips" and several others. And then tighten by hand a little more once the props are on correctly.

Unfortunately if you look at the very 1st post on this topic the pictures with the prop mounted are WRONG ! Don't blame FoxTech for this though - the initial review was
...Continue Reading
Posted by mike_kelly | Mar 19, 2015 @ 05:15 PM | 10,666 Views
One of the most important build issues on a multirotor is reducing vibrations. The motors and props make a lot of vibrations and the flight controller does not like this. The flight controller has a number of sensors that are vibration sensitive. So if you want your multirotor to fly smoothly and loiter accurately you need to get those vibrations down. The problem is that the flight controller sensors need to be firmly attached to the multirotor to sense the movements. So you have a problem, you need to dampen the vibrations from the motors yet you don't want the sensors to get too isolated, using too soft a spongy foam/gel, from what the frame is doing.

That is why a lot of people spend so much time balancing motors and props to reduce vibration at the source.

Another way is to use anti-vibration motor mounts. I bought a set of Tarot TL68B33 (black) and TL68B34(red) to test on my Tarot 650 Sport quad and see if they would really be any help. They isolate the motor vibrations from the arm by adding a little rubber bumper between a motor plate and the motor mount. It did not look like it would do much.

But much to my surprise the reduction in vibrations is quite significant. Vibrations on an APM flight controller are considered acceptable if you can reduce the x-axis and y-axis vibrations to below +-3 units and keep the z-axs to -5 to -15 units. It is not easy to get your vibrations to this low level. I ended up using the RCTimer anti-vibration flight controller mount to...Continue Reading
Posted by mike_kelly | Feb 14, 2015 @ 03:49 PM | 10,699 Views
I just got through with my Tarot 650 Sport build. I was very careful to check that all the rotations are correct.

1. Motors are rotatiing in the right direction on each postion on the multirotor according to the 3DR wiki. Note that the motor numbers are not simply clockwise around the quad, but the motor test in Mission Planner does not follow the motor numbers and simply starts one motor at a time in a clockwise direction.

2. The Clockwise (CW) and Counter Clockwise(CCW) props are on the right motors A clockwise motor needs a clockwise prop. The reverse rotation props are the clockwise, sometimes known as "pusher" and sometimes marked with an "R" like 9045R. The so called normal props are the counter-clockwise.

3. The Radio Calibration is correct
in Mission Planner and the sticks move in the correct directions. Note that the Pitch must move the slider bar DOWN in Mission Planner when you move your pitch stick "forward". All the other sliders move in the same direction as the stick moves.
...Continue Reading
Posted by mike_kelly | Jan 27, 2015 @ 04:52 PM | 11,536 Views
>>> Feel free to post your Tarot travel case solution as a comment at the end of this blog post <<<

Now that I have my Tarot built I need a travel case. The aluminum ones from Asia are way too expensive for me and the Pelican cases are worse. After looking and following other posts I finally came upon the Plano 114400 Bow Case.

This case is 41"x17" x7" which is enough room for the Tarot 650i 650s 680 680 Pro and 690 even with extended arms. It is lockable and has room for my gimbal too.

It comes with a thin layer of pluck foam so I plan to put a layer of solid foam underneath the pluck foam.

It is not a perfectly rigid case like the Pelcan cases. It flexes a bit and it is definitely a cheaper build quality but it is lighter and a lot less expensive.

I got mine off Amazon for $75 shipped.
Posted by mike_kelly | Jan 26, 2015 @ 09:07 PM | 21,605 Views
I have been wrestling with this issue for weeks and I thought I should document what I discovered. Many people these days need to use more channels to control external devices like Gimbals, Lights, Retracts, Camera Shutter and Video switches. For more traditional buillds it is not hard to take the pwm outputs of your reciever and directly connect them to your devices, by-passing the APM flight controller...until you run out of channels. But for newer builds with PPM or S.bus receivers you may not have any pwm outputs to use directly from your receiver. Yes with many Frsky receivers you can do both s.bus and pwm but that is a different story.

So if you are using ppm input to your APM how do you control extra devices?
Mission Planner provides a optional hardware page in setup for APM, it is labeled "Camera Gimbal". It allows you to map input channels from your transmitter to an output pin on the APM board. This is where the documentation gets a little tricky. First APM does not support more than 8 channels. Pixhawk does but not APM. Second the documentation is poorly written and uses duplicate names/labels to refer to multiple different pins.

On the gimbal hardware page there are three control options for gimbal tilt, roll and yaw. But these control options can control other devices than just gimbals. This is not clear in the 3DR wiki.

You can control from your RC Transmitter on channels you have assigned to certain tasks. Say you want to control lights...Continue Reading
Posted by mike_kelly | Jan 22, 2015 @ 10:32 AM | 12,371 Views
One of the fun things about multirotors right now is that we are at the very beginning. Someday soon there will be mostly RTF (ready-to-fly) multirotors out there with all the problems solved. But right now we get to figure it out ourselves and have the fun of designing and solving problems.

One of those problems for me was how to get a video and shutter control cable connected to my Canon S100. I went to Gentles in the UK, who makes lots of different shutter video solutions for RC and he said it was not possible with the Canon S100. What?

So I did some digging and this is what I found. The Canon Powershot series uses a mini USB cable for connection to a desktop computer and for video out. They make a cable for video out, the Canon AVC-DC400 and the Canon AVC-DC400ST. The only difference is the 400 is single-channel audio and the 400ST is two-channel stereo. But why do they also make the USB Cable IFC-200PCU? Why two cables? It turns out that our favorite connector, the mini USB, has many versions. The typical cable that we use for connecting our flight controllers only needs to use a few pins. It needs power and ground and transmit and receive. But the mini USB can have up to 11 pins. It has five on the top side and six on the bottom.

11pin mini USB connector

This is what Canon does; they use the top five pins like any normal USB for communications with the PC and they use the bottom six for video out....Continue Reading
Posted by mike_kelly | Dec 27, 2014 @ 11:17 AM | 11,399 Views
I have been troubleshooting why my 2.4ghz video transmitter and receiver were acting so wierdly. I got video on different channels than are illustrated in the documentation. I searched the internet and found many other people who are confused, but some people seem to do fine with the same documentation.

I finally figured out my problem and it is because I am a "half-empty" guy rather than a "half-full" guy. This is one of those interesting situations where two people can look at the same thing and see two entirely different things. An RC inkblot test.

The whole array of Boscam video transmitters and receivers use dip switches to change the channels for transmission or reception.
...Continue Reading
Posted by mike_kelly | Oct 26, 2014 @ 11:32 AM | 14,739 Views
This is a 7 part series, skip ahead if you like:
#2 Battery Technology
#3 Motors and Electronic Speed controllers (ESC's)
#4 Propellers
#5 Flight Controllers
#6 Radio Control Transmitters
#7 Learning to Fly

Introduction part 1

There is a stampede of new users storming the gates of RCGroups. This is understandable because there are exciting new things happening at a rapid pace, especially in the multirotor category. When you have new technology, there is often a delay in getting out basic information because of the rapid rate of change. I thought I would put down some notes in my blog about what I learned upon entering this new world. These notes are designed to be an overview to get someone started but there is a lot of detail not covered and some ideas are generalized in order to not lose a newcomer.

I started this adventure a couple of years ago because I needed to do some aerial photography. I found the Hawkeye Delta wing aircraft designed for aerial photography:
Hawkeye Thread

It was, and is, an excellent platform but I found that the photography I needed to do could not be done in flight. I needed to hover but, at that time, RC helicopter and multicopter platforms seemed very complicated and way out of my reach. That is why my notes are multirotor-centric because that is my need.

Like so many other people, when the DJI Phantom came out I jumped on it thinking it would solve all my problems. After getting it, I discovered how small and light a GoPro is and that...Continue Reading
Posted by mike_kelly | Oct 26, 2014 @ 11:27 AM | 13,267 Views

Radio Control (RC) models have been around for many decades. They started out with fuel-based engines because the battery technology was not available to store enough energy to enable electric flight. With the invention of the Lithium Polymer (LiPo) battery, electric flight blossomed because it was able to not only store a reasonable amount of energy but it was also relatively light weight. But Lithium Polymer battery technology must be understood by the new RC enthusiast because it can be dangerous if not treated properly. LiPo batteries are made up of multiple cells joined together to create a battery of a certain total voltage. Each cell is about 4 volts, thus two cells (2S) equal an 8-volt battery and three cells (3S) (3x4v=12v) equal a 12-volt battery, etc. You will see people refer to batteries as 2S, 3S, 4S, 5S, or 6S; they are all multiples of a single lithium polymer cell joined together to form a higher voltage battery. If you join two batteries or cells in series the voltage increases; if you join two batteries in parallel, the voltage stays the same but the total energy capacity available increases. If you have six single-cell LiPo batteries in series, it is called a 6S battery with a voltage of 6x4v=24v. If
you have two 3S 1000milliamp (ma) (same as 1 amp) batteries wired in parallel, you have what is referred to as a 3S 2P battery (P=parallel) at a voltage of 3x4v=12v and a capacity of 2x1000ma=2000ma, which is the same as 2 amps. Reading