The Weller Portasol P2C. Soldering gone wireless. Butane instead of electricity. And it comes with a blow torch tip? I didn’t have anything that needed to be soldered, but that didn’t keep me from immediately trying it when it came in. I’ve wanted one of these ever since Andy brought one on our last trip.

For the record, Lauren must really trust me if she gets me a butane-powered blow torch in disguise for my birthday, and then let’s me play with it in our apartment. Thank you.

Ok, let’s take a closer look. Since the P2C is a butane-powered soldering iron, it needs butane fuel. Lauren thankfully ordered a 2.1oz can of it along with the P2C from ToolBarn.com.

The P2C comes with replaceable tips, a nozzle for refueling, a knob for butane gas flow adjustment, an on/off switch, and an ignition switch. It is made of a heat resistant plastic and is, therefore, light even when filled with butane.

Refueling the soldering iron with butane is easy. Hold the soldering iron upside down and mate the tip of the fuel can with the nozzle. Push down with the fuel can for three seconds at a time until it is full. The P2C also features a convenient window to see if you have any butane left.

The butane flow can be adjusted to provide the equivalent power of a 45W to 75W soldering iron.

The front assembly of the P2C can be removed, such that you can replace the tip with any of the Weller Portasol tips. The P2C kit included a 0.094″ double sided soldering tip, a hot air tip with deflector, a hot knife tip, and the blow torch tip shown in the photo.

I cannot wait to put the P2C to good use. Hopefully I will get a chance to do just that on our trip to Ft. Benning, GA to test the autonomous mode of our Flying Android UAV.

If you are curious, check out my Flickr set for more photos of the P2C.

After two grueling months, the wait was finally over. A large, but light, package had arrived in the mail taped shut at one end with Atlantahobby.com packaging tape. Lauren had ordered it for me months ago for our engagement anniversary, but every hobby shop locally and online had it back ordered until the middle of February. It took time for it to travel overseas from Germany.

This weekend it made it here. It took great restraint, but I waited until the next day to open the package. I wanted to make sure I had enough daylight to photo document it, and that is what I did.

I swiftly used my Swiss Army knife to dispose of the packaging. Its contents were what I had been waiting for all this time; my very own Multiplex EasyStar R/C airplane. This is the same aircraft used by the developers of the ArduPilot and our platform for the Flying Android project.

The EasyStar is an ideal platform for learning how to fly R/C airplanes, plus it is actively used for aerial robotics. I plan to pursue both as soon as we leave the unfriendly winter weather behind.

The Multiplex EasyStar comes as a Ready-to-Fly (RTF) kit, so there was little for me to build once I had it unpacked. The Hitec 72Mhz 4-channel single stick transmitter needed eight AA batteries. Replacing the batteries required taking apart the entire transmitter; therefore, rechargeable NiCd batteries should be a wise investment.

Inside of the fuselage is the Hitec 72Mhz 6-channel receiver. Only three of the channels are used on the transmitter and receiver: one for the throttle, one for the elevator, and one for the rudder. This leaves the fourth channel open for customization, which we use for toggling the autopilot on/off on our Flying Android EasyStar. Next to the receiver is the electronic speed controller (ESC) and a NiCd battery pack can be found in the nose of the airplane.

The assembly required to put this airplane together merely took ten minutes. The elevator is glued to the tail and attached to one servo, while the rudder is glued on top of the elevator and attached to the other servo. The wings are joined by a plastic rod and can be easily attached and detached from the aircraft.

I was ready to test the servos and throttle in no time. First, I turned on the transmitter and then the receiver (and vice versa when powering off), else I could risk damaging the servos or other electronics. Then, I verified that the trims and stick moved the control surfaces in the correct directions. Finally, the throttle needed to be tested, so I ramped it up to full power!

I have already started to make a list of modifications in my head: switching over to the 2.4Ghz transmitter from the Blade CX2 helicopter, a brushless DC motor and ESC for more power, and a LiPo battery pack for longer flights. Plus, a camera module is definitely a must.

Make sure to check out my Flickr set for more photos.

A few years ago, my dad entrusted me with his E-Flite Blade CX2 R/C coaxial helicopter, because I became interested in making it fly autonomously. I had a free project in one of my CS courses and decided to build a stabilizing auto pilot for the helicopter around an Arduino Mini, but more on that in a later post.

The helicopter is fairly easy to control indoors, as soon as I figured out to stay way from the ground, the ceiling, or any furniture. Flying too close to any such obstacles creates turbulence and backwash, which make the helicopter difficult to control. This also makes it almost impossible to fly outdoors, even in low wind conditions. The helicopter is powerful enough to lift itself off the ground, but can carry only a small payload of extra electronics. However, it is a lot of fun to fly!

Since the helicopter belongs to my dad, I made sure to take good care of it, but small crashes are inevitable in test flights around the living room in a studio apartment. The worst crash that could happen is a power-on blade strike, where the blades strike an object while the throttle is not at 0%. Either the blades could shatter on impact, or worse the blades are stuck, which cause the DC motors to over-current the 4-in-1 control unit. As Murphy’s law dictates, just that happened to me.

The short in the control unit from the over-current remained well hidden, since there was neither a spark nor a small puff of smoke: the #1 sign for any electronics geek that something just broke. I didn’t know something went awfully wrong until the next time I tried to fly the helicopter.

Plug the battery pack into the control unit. Go. Turn on the transmitter. Go. But the transmitter wouldn’t associate with the receiver in the control unit, which simply blinked red and green. Ok, let’s try it again. Unplug everything. Plug the battery pack in and turn on the transmitter. Same red and green blinking. Oh, no. Panic. Let me read the manual. Rebinding? I tried to rebind the transmitter and receiver with the bind plug, but that didn’t fix it either!

I spent the afternoon frantically searching the Internet for a solution, until I came across a discussion about Blade CX2s and the ‘over-current’ problem. I soon learned that the control unit was lost and this could have been easily prevented with a fuse between the 4-in-1 control unit and the DC motors. A $5 fuse? Why wasn’t this included with the helicopter in the first place? Needless to say, I was a bit furious that I had to replace the $60 control unit.

So before you have to spend $60 to replace a destroyed 4-in-1 control unit, invest $5 in resettable fuses (EFLH1206 Over-Current Protection/PTC Fuse Harness). These positive temperature coefficient (PTC) devices are non-linear thermistors, which at some specified level of current break the circuit and disconnect the motors from the control unit. The fuses reset once the current drops off on the wire.

The resettable fuses need to be installed between the control unit and each motor (not the servos). Check the photo below to see what it should look like installed on your helicopter. The fuses will add some length to the wiring, but you can easily stow them away in the cockpit above the control unit.

If you’re lucky, you may have bought one of the newer Blade CX2s, which now ship with the fuses already installed. Either way, next time you get unlucky with a power-on blade strike, you won’t blow your fuse over having to replace the $60 control unit.

Lauren and I were ready for SparkFun‘s Free Day. The night before we had filled up our shopping carts with $100 worth of electronics (and some sweet t-shirts). I had filled my cart with two XBee Pro 900 RF modules with an antenna, which I have wanted ever since the FunJet UAV has been on the home page of DIY Drones. These modules have a range of up to six miles and would be great for telemetry from an UAV down to a ground station (read: laptop).

We woke up at around 10:15 AM and pointed our browsers to our shopping carts. Thankfully, SparkFun had a live countdown to follow. My dad joined a little later, and Andy and I were giving an almost play by play over Twitter. At exactly 11 AM, all of us and the rest of the Internet hit “Checkout!”

Loading… Timeout. Refresh. Loading… Timeout. Refresh. This went on for almost two hours. My dad couldn’t get registered. Lauren only ever saw her shopping cart. I timed out trying to pay for shipping. And Andy made it to the last page, but then after 1 hour, 44 minutes, and 47 seconds, Free Day ended and none of us got any electronics.

On a more positive note, SparkFun became the #1 Google search term, #sparkfun grew into a top Twitter trend, and their store got some much deserved publicity!

Hallo.

To kick off this blog, here is a photo of one of my current projects: a Multiplex EasyStar R/C aircraft + Google Android developer smart phone = Unmanned Aerial Vehicle (UAV). This photo was taken on a cold, rainy, and windy day in early December at Ft. Benning, GA.

The UAV is remotely operated by a safety pilot on the ground, while the smart phone records sensory information and takes photographs. Below are just a few of the photos captured during one of the test flights at altitudes between 300 and 500 feet above ground level (AGL). By the end of this two semester project, the team plans to demonstrate fully autonomous flight of the UAV.

I develop and implement the flight controls in the autopilot. In the first phase of this project, I ported the ArduPilot to work on the smart phone and its Android platform. The flight controls consist of simple proportional-integral-derivative (PID) controllers, which adjust the elevator, rudder, and throttle. The accelerometer, digital compass, and GPS receiver on the smart phone are used as feedback in the control loops. I plan to explore more complex control strategies in the second phase of this project.

We plan to extensively document our project on flyingandroid.com, including how to hack the serial interface on the G1 and some other creative ways to connect smart phones to servos.