Teksumo Build Log 05

Got a lot done today! First up, getting the motor all assembled up.

Loctite 242, the temporary one, was used on all the metal/metal screws to ensure they don't vibrate out during flight.

A hole was drilled in the motor mount for the shaft to go through, and the prop is put in place, ready to go. Unfortunately, I need some screws, washers and nuts to complete this stage, so I've put it aside for the moment.

Next, I tackled the servos. By default, the slots are for the smaller sized servos, but I've got the larger metal geared ones. I saw some people buried their servos inside the wing to reduce drag, so I've done the same.

Instead of having the servo vertical, I agonized for long hours (more like 15 mins) about how to place them. I decided, that since we want to a) make sure the least sticks out along the upper camber and b) the weight needs to be closer to the front of the plane.

As such I cut out a hole exactly the size of the servo in the wing, allowing the servos to be totally buried in the wing. The fit is very snug, so I think maybe a dab or two of glue along the edges should hold them in, and I will tape it over with some duct tape.

I still haven't decided how to route the servo leads, but I've seen that a soldering iron can be used to cut a groove in the foam for the leads to run in, which is again covered over in duct tape.

I still haven't gotten around to joining the two wing halves yet, but I've got some basswood, and cut it out in the outline of the cross section of the airfoil. It is my hope that I can use this as a guide later in order to create an upper section (perhaps) to hold the electronics.

I've never heard of basswood until today. There is an arts and craft place in the city called Michaels, and they carry a surprisingly large choice of balsa, basswood and plywood of various dimensions. I'd actually gotten piece of balsa yesterday (it can be seen holding down the battery connectors in the previous log entry), and while I had tracings of the cross section on them, I didn't cut them out yet.

The bass wood is much denser than balsa. On the flip side, it's very resistant to crushing, unlike balsa which gives under my fingernails. While the basswood is much harder to work with, it isn't _too_ much more annoying. The piece I've got is 2.3mm in thickness, and it rapidly melts under the attention of 60 grit sandpaper.

Will have to start thinking about getting the control rods in. I've bought some really nice looking nylon ones from the hobbyshop, but that'll be in another post!

Teksumo Build Log 04

Finally got around to soldering the ESC and another motor... and only realized after, that I totally forgot to measure the lengths of the cable >.>

On the flip side, I'm not yet 100% decided on the placement of the electronics so....

Teksumo Build Log 03

While this is the 3rd "Build Log", I've done nothing more than grouse and show photos of the various components. And this one is no different! I started out with bare curiosity, how heavy is the bare wing?

Evidently, the raw EPP foam wings - and the carbon fiber spars - weigh in at 172 grams. No idea how accurate this scale is, so assume this is a good estimate. Now let's pile on the rest of the LOS equipment:

This jumps the weight up to 485g. It's interesting to note, that the 2200mah 3S Turnigy Nano-tech batteries are... 177g. What's missing here is the receiver, which is probably around 10 grams? Add in the additional weight of the glue, and running longer cables etc, I'm probably in the 500-ish gram range.

According to this online calculator, the drive train should provide more than its weight in thrust, so hopefully I can throttle back to a lower speed for long cruises.

As for positioning the components. I will be putting them on the top side of the wing, as I think landing on the battery, receiver and speed control is a rather bad idea. There are already 2 compartments cut open below for the recommended battery and electronics, so I need to figure out how to fill in those openings, and then cut my own openings up top.

The servos for the elevons also brings up yet another interesting issue. The original placement (see where the multi tool is pointing) gives it probably the best leverage against the elevon, but the servo cable is simply not long enough to reach the receiver if it's mounted in the main electronics bay.

So either a) I run the servos closer to the center bay, or b) I get extension cables, which adds weight.

This also does not include several other items that I want to include down the road:
- FPV Camera
- Video Transmitter
- OSD (on screen display - basic stuff like battery levels, but can be more like heading or attitude indicators)
- Gopro/action cam

The Gopro itself is just over 80 grams, so that brings the aircraft very close to 600 grams all up weight (AUW)! Adding in the OSD/FPV gear will probably add another 100 grams, so maybe 700 grams in total? But we'll see.

Teensy 3.1 too fast XD

I've been experiencing very odd cases of the AHRS system simply updating very slowly. If I were to update the exact same sketch again, it'd work as I'd expect.

After much troubleshooting and getting nowhere - I thought my use of the IntervalTimer was causing issues, but it was not so - I loaded up the example Sparkfun sketch, and noted that when I plug in the board the first time, the gyros won't updated, only the accelerometer and magnetometer!

If I then upload the exact same sketch, the gyro would run. I thought perhaps the servo was drawing too much current, but no, that wasn't it. I gave up and asked the forums, and got a quick reply by the creator of the Teensy rather quickly! He suggested dropping in a delay before I initialized the sensors, and that did the trick!

Evidently, the Teensy boots up really fast, and the call to initialize the sensors was done before the sensors were properly powered up. That's another thing learnt today! Thanks Paul!

Teksumo Build Log 02

Only had a little time today, so I started checking out the parts that came with the Teksumo. The assembly instructions that came with it make it sound so easy, but sadly I didn't buy the recommended parts, so I'm having to deal with several issues.

First up, is the motor mount. Sadly, it will only allow one way to mount the motor, and that's with the bulk of the motor behind. Which means I can't attach the prop to the motor's shaft.

More importantly, the shaft intersects with a portion of the motor mount! (!!!!)

As you can see from the picture above, the shaft extends out into the wood. Argh! No matter, I have the FC 28-12 mentioned previously that spins like a regular motor but.....

It's motor mount is too small XD I need to drill some holes for this baby to work.
So either I remove some wood to fit the SK3 28-26 1130Kv motor, else I need to drill holes for the 1534kv. Decisions, decisions. Gah!

And let's move on to the next subject, servos!

Again, the 5g servos won't fit into the pre-cut slot! Luckily (and surprisingly), the servo fits into the plywood mount. At least there's that. Also, the servo cables do not seem to reach long enough to where the receiver will be. So, unless I run extension cables, I could take this chance to make a bigger hole closer to where the receiver is.

We'll see :)

Teksumo Build Log 01

Finally! After 10 days, my order from Hobby King arrived here in Vancouver. Surprisingly, it was sent out from Singapore, not Hong Kong. But whatever, it's here and I'll start the build (hopefully) on Thursday, as I am attending the Vancouver Houdini User Group tomorrow!

My toys arrived in a largish box, with the Teksumo in its own box at the very bottom, and the rest of the parts were firmly surrounded by little air bags in the middle of the box.

Let's take a quick look at the Teksumo.

I can't wait to glue her together. Next up let's take a look at some of the other parts that will make up the build. The servos are Corona 929MG servos. These were chosen because of the metal gears used inside. Supposedly, it's really easy to strip the plastic gears in the servos of flying wings when "landing", so several people have recommended running metal gear'd servos. Not bucking that trend!

Ah, the motor. There are simply too many choices and suggestions available. I picked up the Turnigy Aerodrive SK3 - 2826-1130kv. Being my first build, I have no experience with choosing brushless motors. The general idea though, is that lower kv motors (kv indicates how many rpm the motor will spin per volt without load) have higher torque and can spin a bigger prop, while the higher rpm motors that draw the same amount of power should use a smaller prop.

The motor is elegant, shiny and just needs to be caressed. The motor arrived in it's own little black glossy box, with the insides padded out with foam. In side, apart from the motor, contains two prop adaptors, the motor mount, as well as the mounting hardware.

This motor appears to have two configurations; by attaching the prop onto the shaft, the bulk of the motors weight is now moved forward - for a flying wing anyways. This is probably the configuration I will use, unless the plywood mount on the Teksumo doesn't allow it.

The alternative configuration is to have the prop directly mount on the outrunner. I feel this is not a good idea as the prop adaptor here consists of 3x M3 screws that connect to the outrunner's bell. Not a structural engineer, but I feel this is a weaker option of the two, and the mass is now pushed further back.

I say this now, but I've not yet attached all the electronics; I may end up running the later configuration to get a good center of gravity (COG). Next up is a speed control. While the chosen motor is rated for a maximum of 13A on paper, the engineer in me says best to have a higher upper limit, hence the 30A choice vs a 20A speed controller. It weighs somewhat more, so we'll see. The ESC does not have plugs attached on the battery/motor end.

Propellers! Again, no idea which prop will fit which best, so I've bought a smattering of props from TGS and APC, in 8x4, 7x6 and 7x5 options.

Next up, is some connectors. The orangey XT60 connectors on the left are what's used on the larger capacity Turnigy batteries, so additional sets are needed to get the ESC to work with them. The right side is some 3mm bullet plugs, which is what's attached to the brushless motor, and I will be soldering 'em to the motor end of the ESC as well.

Other parts I bought to help include a prop balancer, a power meter, and a tiny OSD for when my camera arrives.

I'm still missing a few things, and I hope they will arrive in a few days. First up, my receivers! I bought a LemonRX DSMX receiver with it's satellite straight from the source in Taiwan, and it's almost two weeks, hopefully it won't take too long to arrive as I can't really test my ESC or motors without a receiver!

Various glues are required as well:

• Amazing Goop: To join the wing halves
• Loctite 242 Blue for any metal/metal screw contacts
• Wellbond: Bought on a hunch that it may be useful for wood.
• Gorilla Super Glue Gel: Already had it to repair my other planes/helis.

Batteries have been mentioned in an earlier post; I got 3 Turnigy Nano-techs, each having a capacity of 2200mah.

FPV gear wise, I am still waiting on the camera to arrive from Banggood. It _should_ work with the lcd rx I have. Fingers crossed!

And, I think that's it! I will be building the Teksumo for pure line of sight (LOS) flights first. Once I've gotten used to it how it performs, then I'll put the fpv gear on.

---------------------------------------------------------------------------

I've also bought an additional motor, the FC 28-12. This motor runs much faster than the SK3, at 1534kv. However, in my newbieness, I did not know that I was also supposed to purchase either a prop adaptor or prop saver to use with the motor; unlike the SK3, it did not come with any equipment to mount the props.

Crashtesthobby reports running this motor for over half an hour, so I'm hoping that either this or the SK3, with it's relatively low power needs, will give allow me nice long flight times with the props I have.

Roll/Pitch estimation with an IMU

For some reason I've been suddenly yearning to learn more about attitude estimation. So, over the last two weeks, I've spent a good part of many evenings trying to figure out the maths behind this.

Initially, I was following the A Guide To using IMU in embedded applications. At the start, the maths was ok, and I learnt a fair few things, but towards the end I was unable to understand how the yaw estimation is done (I have read that yaw estimation without a magnetometer is basically dead reckoning; lots of drift.), and simply implementing the instructions the best I could unfortunately did not yield any results.

Next, I found this other tutorial, Reading a IMU Without Kalman: The complementary filter. Based on Pieter's post, I got my roll/pitch estimation working in short order. I am still not 100% understanding how the complementary filter works, so I'm going to spend some more time looking at the values closely.

The Teensy 3.1 is a new mcu for me, but I've worked with the Teensy 2, and the way it works in the Arduino software package appears to be very similar for my newbie needs. I was having difficulty trying to get timed function calls to work with the various built-in arduino packages e.g. timerOne, but finally found IntervalTimer and it works a treat. I have my code block execute every 10 milliseconds, and the code takes less than 2 milliseconds to execute. Lots of spare time! Must be the Cortex M4 running at 96Mhz :3

The sparkfun board was very well thought out, for my needs, almost everything was setup on the board, from pullup resistors to the setting of the i2c addresses. All I had to do was connect the vcc/gnd and i2c data/clock lines, and that was it! The library provided by Sparkfun also worked with no drama. Very, very slick. I like this!

The Processing sketch was also _rather_ straightfoward. Apart from the fact that it was using the left hand co-ordinate system and confused me utterly till I went through some examples. The Teensy sends out the roll/pitch values after every timestep, and inside processing, I use the serial event handler to call a drawing function when new serial data is sent. Easy.

Now that I have a reasonably working IMU, I am going to use it to learn about PID Control before I try to figure out the Madgwick Algorithm for using the magnetometer as well.

Hmmm digital i/o

I think thus far, all my previous experiments have all been done using analog sensors. This time, all the sensors I have communicate with digital i/o, and most connect via i2c and my imu supports both i2c or spi.

Being an i2c newbie, the two wire interface is a whole new world to explore. Previously, with analog sensors all I needed was to connect up the sensor to the mcu's ADC, and that's it. Here, it seems like it will take me ages to figure out how to utilize the interface as well as the various control codes to send over the bus in order to get things moving.

Thankfully, companies like sparkfun and adafruit etc provide libraries that slot neatly into the Arduino software, and the last library I tested for the BMP180 from sparkfun worked out of the box with the Teensy 3.1

So, instead of messing around with lower level stuff, I can just call a function to do what I need. Let's see how that goes!

Sparkfun ITG-3200 Gyro

This is an impulse buy, plain and certain. Last night, I was puzzling around how r/c helicopters are able to maintain a certain attitude with only a 3 axis gyro.

Now with a helicopter, you have the main rotor up top spinning clockwise providing you with lift. However, this causes a problem, as the torque generated by the motor will cause the body of the helicopter to spin anti-clockwise. That's the reason why most helicopters have a smaller rotor at the end - to counteract this spin.

R/c helicopters use a gyro to maintain the orientation of this tail, with the aptly named "Heading Hold" gyro. Being stupid inquisitive, I started reading up on the possibilities of creating a DIY "Heading Hold" gyro.

I was very curious, and a quick google indicated the gyro used on my mCPX BL is the Inversense ITG-3205 (nigh impossible to see in the photo below). The 3200 is a similar part, and as it was at RP Electronics, I was like... if it was used on the mcpx bl, it means it's good enough for experimenting with!

Now as with all impulse buys, I didn't check the spec sheets comparing the itg3200 to what I _already_ have, the LSM9DS0. But to be honest, I'm not exactly sure what to pick up. Now that I have got my headers all soldered into my mcus, I'm ready to rock me some programming!

RP Electronics

I ran out of headers for my boards, so decided to take a jaunt down to RP Electronics in Burnaby. They are in a perfect location, just a few minutes away from the Rupert Skytrain station. I thought it would be another small place like Lee's Electronics, but no, what greeted me was the Ikea of electronics.

I only came in to pick up some headers and female jumpers, but found out that they carried Sparkfun stuff! Not only Sparkfun, but Adafruit, Seeduino, even Teensy 3.1 boards were available! I was in heaven :3

I bought a Sparkfun Inversense ITG3200 gyro. More on that in another post!

Syma S107G... to hack?

This little baby arrived yesterday (with the batteries), but I only got around to actually checking it out this evening.

The... container it arrived in was rather amusing. It was simply two styrofoam halves heavily taped over in yellow packing tape. Inside, contained the helicopter, a usb charger, the transmitter and some instructions.

I bought this heli for several reasons, first, to check out shipping times of banggood to Canada (just over 2 weeks), to check out co-axial helicopters as well as hoping to use it as a development platform to learn how design a simple pid controller, and just generally curious how two motors could power those counter-rotating blades.

I'm probably way over my head, and should start with something ground based like a balancing robot, but we'll see.

It seems like the upper set of blades runs a solid shaft, while the lower set runs a hollow shaft, and each motor runs one set of blades. Here's the interesting challenge - to get the helicopter to hover and keep its heading, ideally using a barometer to keep its altitude from the ground.

Pretty sure it can be done, and I'm very curious if I can work out how to get all these things working.

I also flew it for a few minutes, and it's really very docile. In fact mine can easily just float in place without any input once I have it at a good throttle setting.

It is also noted that these helicopters are not suitable for outdoor flight, and I can tell you, don't try it unless there are no winds! I had my fan pointing at me (you know where this is going) and I had the heli cross the air stream.... and it got blown right into my face! It got me in the lower jaw, smarts, but it didn't draw blood or leave a mark.

This heli is a 3 channel helicopter, only allowing the pilot control of the throttle, pitch and yaw. The transmitter I have is setup for Mode 4; left stick only controls the throttle, yaw and pitch on the right stick.

This setup is rather confusing to me as most people fly mode 2 for helis (throttle and yaw on left, pitch and bank on right). In addition, the lack of banking means it's actually not that easy to land. On my mcpx I could just set down willy-nilly on my desired spot. Without bank controls like this heli, means I actually have to plot a proper flight path to land on, and if I miss my landing point, I need to feed in some throttle, turn around and try again.


There is also a very cool blinking red/blue LED upfront, which I thought was Yeah whatever, but in actuality, it's pretty damned cool to see blinking leds flying around XD

What else... unlike the hobby grade crap I fly at 2.4ghz, this heli is controlled by IR signals, so not a good idea outdoors in the sun. Charging it up is quite convenient, the controller (using 6 AA batteries I might add) has a small slide-down door that has a tiny charging cable to plug into the heli. In addition, there is a usb charger as well so you won't drain the transmitter's batteries.

For $27CAD - shipping included! - this is a great entry level helicopter for kids, and quite nice for performing experiments on. In addition, the helicopter is solidly made from plastic and metal, and feels quite good in the hand. Softer plastic is used for the rotors, so hopefully crashes will keep it going.

Batteries from Hobbking USA West Warehouse

Over the weekend, I decided to build a Teksumo flying wing to explore fpv flying. I actually called up my local hobby shop to see if they sold any flying wings, but it seems like the few I've visited mainly stock Horizon Hobby products, so basically no.

Hobbyking operates from several locations, and I bought most of the parts of the aircraft from their so-called "International" warehouse. Batteries though, I decided to purchase from the West USA warehouse. They arrived surprisingly swiftly; ordered late on the 16th of August, and it arrived today, the 19th!

The batteries arrived well packaged, and each battery actually came with it's own box and instruction sheet, as well as being sheathed in two layers of bubble wrap.

I'm assuming there will be some kind of brokerage charge in the mail, I'll update this post when that happens. I'll also run a build log once all the parts arrive.

ARGH! Hardly able to fly my heli >.>

I've been having a thoroughly bad run with my mCPX, I think it's close to two weeks since I last flew it! The last time I took it out, the battery lead that is connected to the board fell out. No big deal, since I have a soldering iron.

Or do I?

Seems like my butane iron's tip has worn out after years of service, and refused to light up. Today, the spare I ordered finally arrived, and YES! I can fix this. I proceeded to take the flight board off the heli, and while pulling off the servo connectors, pulled out one of the connectors on the board.

ARGH!

It's a SMD solder joint, and I do not have the tools or know-how to fix that. I've sent an email to Megas's Micros as they do board repairs. Hopefully I will get this fixed in a few weeks. In the meantime, I can get on with setting up my IMU and stuff with my teensy 3.1 :)

Complementary Filter Success!

Back to tackling this old problem of how to get clean sensor data. Previously, my tests were using simple low pass filters, which, while simple, produced major lag. Recently got hit by the "OMG I MUST CODE A KALMAN FILTER FOR IMU" bug, and started doing classes with Khan Academy, Youtube etc. in physics and statistics. I finally get what a co-variant matrix is... sort of. But a Kalman filter is really beyond my ken at the moment, and decided, hey, that can take longer to study. It's not like world peace will magically appear if I learn how to code one. The suggested alternative, is the complementary filter.

While I do have my electronics kit and kaboodle with me in Vancouver, one BIG component is not working - the tip of my soldering iron appears to have died >.> And the replacement is apparently in the mail, for over a week now. So I can't really do much more than drool appreciatively at the new 9DOF sensor board on my table. In the mean time, apart from doing my studies above, I found some sample data (google for "sample data freescale") online and started messing around with them in Processing.

After going through many complementary filter links, I found one that finally "clicked" for me. While I mostly understand how to implement it (especially after the physics classes), after reading so many forums and sites, I'm pretty sure I'm missing some of the finer key points.

In other news, I've purchased a Teensy 3.1, which I hope will arrive sometime soon. This is my 2nd time playing with arm chips, can't remember why I sold off my Arduino Due.

Really pointless review of "Syma X5C-1 X5SC 5.8G FPV 720P Camera with Monitor Real Time Transmission"

Ok, so one fine day, I was chatting to a colleague about how affordable it is to buy a toy quad nowadays, and pointed him at the Syma X5C-1 on banggood. Whilst I was browsing the selection of quadcopter options and parts, this set jumped out at me. For about USD50, you get a FPV camera and a receiver. After reading some comments about the lcd being able to receive signals from other brands of transmitters, I impulse bought it.

I must say I am still slightly irked at this impulse buy because I can't actually use it! The fpv vapor - which I was hoping to test fpv with - does not run on the same frequency bands, and I don't have any aircraft that will carry the fpv camera. (The FPV Vapor has been put up for sale btw.)

In any case, I was very surprised by what you get in the package; the lcd receiver, the fpv camera/tx, combined charger, as well as a bang containing parts to attach the lcd panel to your Syma transmitter. Note: If you buy this, open the paper box *carefully*. Mine had a whole bunch of tiny screws for the transmitter attachment fall out, as the plastic bag containing them was mysteriously ripped apart.

There are no operating instructions included. The box itself is also not very helpful; the best it could do was tell me which bands it supported - I have no idea which channel is assigned to which dip switch! Thankfully, so long as the dip switches match between the transmitter and receiver, it works.

The lcd receiver appears to work on the 5.8Mhz Band with 8 channels. It seems like the more expensive models online have 32 channels. The included antenna appears to be a patch antenna.

The fpv camera comes in a single unit with its transmitter. What appears to be nice is that the transmitted signal also included an onscreen display of the tx battery lifespan. More on that later. There is a slot to insert a micro sd card, and another slot for charging. A cable snakes its way out of the tx, which I assume is for connecting to the quadcopter to engage/disengage the camera in-flight.

Now, previously I'd read a horror story of an Hubsan X4 battery charger overcharging the lipos and blowing up. The charger included looks exactly the same as my X4's charger, so, first thing I did was to take apart the whole thing and observe the battery voltage with my multimeter.

It seems like the battery in the receiver cuts off at around 4.22 volts (a red led goes off the receiver's pcb), and the fpv camera's battery at 3.9 volts. This sounds good. Tad worried about the 4.22 volts, but you know, I'm using a cheapo multimeter. It's possible it's just not that accurate. One other thing to note, the charger is a USB charger, and has a LED that lights up *after* the charge is complete. Quite disturbing until I figured that out (I was like... why did the led go off when I put the charge plug in?! Is it a short circuit?! Thankfully not, as my multimeter indicated).

The charging appears fine and dandy, but the on screen display tells another story - the rx, even though fully charged only shows 2 out of the 3 bars of charge onscreen. Tricky. The tx display shows 1 of 3 bars.... so maybe something's off with the charge since it stopped at 3.9 volts.

As to why I'm saying this review is pointless.... is because I've never tested it out in the field and have no idea what the range is like. Could be a hundred meters, maybe a few klicks (supremely unlikely) or maybe the signal dies whenever I start singing. Who knows.

Overall, the kit seems to work well. Viewing angle is quite washed out at oblique angles - but can you really complain about that for the price?! And the refresh rate seems really good even in low light, and it's super light as well. This is a good first step to getting a toe wet with fpv.

I'm looking into getting a flying wing to host the camera, and hopefully one day soon I'll report back on my first fpv flight!

Blade Inductrix BNF review

 

I actually got my Inductrix over the weekend, and I was hoping to use it to try my hand at doing a video review. Unfortunately, I do not have a means to charge my digital camera - I only have a UK plug for the charger, and I simply cannot find an adaptor for UK to Canadian plugs! 

The GoPro OTOH works fine and dandy, but realized that the fixed focus means that objects close up are very blurry. After being unable to find a plug converter, I finally decided to just snap some pics with my dslr and write a small review of this new toy.

When I first saw it, I was extremely surprised at how small it really is. I always figured it to be the roughly the size of the Hubsan X4 from the videos, but it's far smaller. Four-bladed props spin inside the protection afforded by the translucent ducts. Two pairs of LEDs serve to indicate the front and rear on the bottom of the quad (can you tell from the photos, which edge is the front?). Two more leds, a red and blue pair, ride on the upper side of the pcb, the blue indicating stability mode (self leveling), and the red lights up when agility mode (aka rate mode) is active.

The Bind and Fly set I bought is extremely simplistic and well thought out with minimal space wastage. The package contains the Inductrix, a spare cover (a fine surprise!), a 150mAh 1S lipo battery, a USB charger for said battery, and instructions.

Binding it with my DX6 was effortless. I just picked a new aircraft model as my base setup, bound it and that was it. I did not even have to trim it!

How does it fly? Well it's very, very stable - or very unstable, as aerobatic pilots may say. The quad self-levels instantly, and combined with its small size and protected props, make it a joy to fly indoors. If it's out of the path of wind my fan blows, it appears to be able to hover in place easily.

I doubt it will do well outdoors, as the small fan in my room pushes it aside quite easily. While it can fly against the breeze, I really doubt this was what it was designed for. Rather, indoor flights would be its forte.

Flight time is about 5 minutes before the low voltage cutoff engages. Unlike the Hubsan which decreases performance when the LVC is activated, the Inductrix simply flashes its LEDs and just drops straight down to the ground. Always remember to set a timer on your radio if it has one! Remember, low voltages kill lipo batteries!

Speaking about dropping it on the ground, the quad took some of my rate-mode flying (more on that in a bit) with gusto, bouncing off the floor and furniture with nary a touch of damage. While I don't advocate full throttle into the walls, I think for learning how to fly a quad, this is a great choice as the props are well protected, and I can't see needing to replace them unless I get into a *really* bad crash. The tips of the props do extend above the fan ducts, so not a good idea to "ceiling crawl" :) Another minor point to note is how quiet this quad flies. This is the second quad I've flown, and probably the quietest little thing ever. Flying this quad at home during reasonable hours should be fine, unless you've got paper thin walls or neighbours with super ears!

Now while this is a beginner's quad, it's possible to turn off the self-leveling and switch to rate mode flying, which will probably appeal to the more experienced pilots out there, and masochists like myself. One of the reasons why I bought this, is to practice flying a rotorcraft indoors in rate mode like a cp helicopter. And the Inductrix in rate mode is very similar to flying a cp helicopter.

While I do have a mCPX BL, I hardly have the skill to fly it indoors, and even just hearing the mCPX BL spool up in its lower RPMs is still very unsettling. Heck even spooling up outdoors, I keep a good distance away! But I digress.

Now, flying the Inductrix at 100% travel is actually very sedate with self leveling on. Pushing the servo travel to 125% gives it very nice oomph to buzz around. However, once in rate mode, it's a bit too much for me to handle, and putting in some expo on the controls really helps tame the quad down. I personally have 3 flight modes on my radio for the Inductrix (like my heli), each with gradually more travel, so I can hand of flight mode one to a newb to fly with self leveling and low travel, and I can quickly move back to rate mode + high travel with a flick of a switch and press of a button. In addition, I also have a throttle cut switch for when I'm connecting up the battery.

With the DX6, setting up the quad for rate mode is quite straightforward. Simply assign the "gear" channel to channel 6 on the RX, and assign it a switch. I assigned it to my radio's bind button, so a single click will switch the self leveling on/off. You can also assign it to a toggle switch, but I found a single click easier than toggling a switch.

Things I wish would have been different on the Inductrix:

• The front/rear LED indicators are not the best from a visibility standpoint, and I'm guessing the LEDs are placed where they are, on the control board itself, so as not to have to run 4 additional pair of wires. Less things to snag on, lesser things to break, weight savings etc. etc.
• Some better way of telling where the front is, be it by colour coded props or some canopy design.
• A yellow cover. mCPX Yellow. Red is nice, not a fan of blue, but I think yellow r0xx0r! Yes, this is a first world problem :P

Last thoughts, I think it's a great small quad for indoor flying, and if you get bored of it, flying it in rate mode will defo give you an exciting challenge!