Flight For Your Right (And Do It By Friday)

Model aircraft

About a month ago, the FAA – the governing body for nearly everything that flies in US airspace – proposed an interpretation of their rules governing model aircraft. The world hasn’t ended quite yet, but if the proposed rules go into effect, an entire hobby will be destroyed in the United States. While congress has given the FAA authority over nearly everything that flies, there are specific laws saying what the FAA has no jurisdiction over – model aircraft being one of the major exceptions.

Congress, however, is working on a definition of model aircraft that is at least 10 years out of date and doesn’t have any leeway for the huge advances in technology that have happened since then. Specifically, all FPV flight with video goggles would be banned under the proposed FAA rules. Also, because model aircraft are defined as being for, ‘hobby or recreational purposes,’ anyone who flies a model aircraft for money – a manufacturer conducting flight tests on a new piece of equipment, or even anyone who records a video of their flight, uploads it to YouTube, and hits the ‘monetize’ button – would be breaking the law.

The proposed FAA rules for model aircraft are not in effect yet, and you can still make a public comment on the proposal until 11:59 PM EDT Friday. If you leave a comment, please make a well-reasoned statement on why the FAA’s interpretation of the rules governing model aircraft are overly broad, do not take into account technological advances made since the drafting of Congress’ working definition of ‘model aircraft,’ and the effects of a complete ban flying model aircraft for any type of compensation.


This is not a good comment.

Of course, if the proposed rules for model aircraft go through, the only option will be to turn to the courts. Historically, the FAA simply does not lose court cases. Recently, cases involving drones have come up with successful defenses and judges deciding in favor of drone operators. The legal services for the eventual court case challenging the proposed FAA rules will most likely be funded by the Academy of Model Aeronautics, who just so happen to be offering membership at 50% off.

Below is a video of some RC people we really respect – [Josh] from Flite Test and [Trappy] of Team BlackSheep – talking about what the proposed rule change would do to the hobby. There’s also a great podcast featuring the first lawyer to successfully defend drone use in federal court that’s worth a listen.

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Independent Wheel Drive R/C Car


The picture above looks like a standard four-wheel drive (4WD) touring car. As one looks closer, a few strange things start to pop out. Where’s the motor? 4 electronic speed controls? What’s going on here? [HammerFET] has created this independent drive R/C car (YouTube link) as a research platform for his control system. The car started off life as a standard Schumacher Mi5 1/10th scale Touring Car. [HammerFET] removed the entire drive system. The motor, differentials, belt drive, and ESC all made for quite a pile of discarded hardware.

He replaced the drive system with 4 Turnigy brushless outrunner motors, installed at the chassis center line. To fit everything together, he had to 3D print new drive cups from stainless steel. The Mi5′s CVD drive shafts had to be cut down, and new carbon fiber suspension towers had to be designed and cut.

The real magic lies in [HammerFET's] custom control board. He’s using an STM32F4 ARM processor and an InvenSense  MPU-6050 IMU which drone pilots have come to know and love. Hall effect sensors mounted above each motor keep track of the wheel speed, much like an ABS ring on a full-scale car.

[HammerFET's] software is created with MATLAB and SimuLink. He uses SimuLink’s embedded coder plugin to export his model to C, which runs directly on his board. Expensive software packages for sure, but they do make testing control algorithms much simpler. [HammerFET's] code is available on Github.

Since everything is controlled by software, changing the car’s drive system is as simple as tweaking a few values in the code. Front and rear power offset is easily changed. Going from a locked spool to an open differential is as simple as changing a value from 0 to 1. Pushing the differential value past 1 literally overdrives the differential. In a turn, the outer wheel will be driven faster than it would be on a mechanical differential, while the inner wheel is slowed down. Fans of drifting will love this setting!

[HammerFET] is still working on his software, he hopes to implement electronic torque vectoring. Interested? Check out the conversation over on his Reddit thread.


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Droning On: PID Controllers and Bullet Connectors

droning-on-hill Not all drones are multirotors – Posing in our title photo are Maynard Hill and Cyrus Abdollahi. Maynard’s plane, TAM5 aka The Spirit of Butts Farm, is the smallest aircraft to make a transatlantic flight (YouTube link). Retracing the path of Alcock and Brown from Newfoundland to Ireland, the 6 pound (dry weight) model made the trip in just under 39 hours. All this happened in 2003, and was the cap on a lifetime of achievements for Hill. These are the types of pursuits that will be banned in the USA if the FAA restrictions go into effect.

Flight Controllers

Quite a few of you thought the Naze32 was left out of last column’s flight controller roundup. I hear you loud and clear! I’ll add the Naze to the controllers which will be tested on The Hackaday Testbed. The hard part is finding the darn things! I currently have an Acro Naze32 on its way to Droning On HQ.  If I can find a full version, I’ll add that.

PID Controllers Deep Dive

I’ve gotten a few questions on Proportional Integral Derivative (PID) controllers, so it is worth diving in a bit deeper to explain what a PID controller is. PID controllers are often found in process controls managing parameters like temperature, humidity, or product flow rate. The algorithm was initially designed in the late 1800’s as a method of controlling the helm of large naval ships. In fixed wing drones, PID keeps the plane’s wings level and on course. In multicopters, PID loops control heading, but they also provide the stable flight which allows the quadcopter to fly in the first place. A full explanation of PID loops would be beyond the scope of a single article, but let’s try a 10,000 foot explanation.

pidP: This is the “Present” parameter. P Has the most influence on the behavior of the aircraft.  If the wind blows your quadcopter from level flight into a 30 degree right bank, P is the term which will immediately take action to level the quad out. If the P value is too high, The quadcopter will overshoot level flight and start banking the other way. In fact, way too high a P value can cause a quadcopter to shake as it oscillates or “hunts” for level. Too Low a P value? the quadcopter will be very slow to react, and may never quite reach level flight again.

I: This the “Past” parameter. The I term dampens the overshoot and oscillations of the P term, and avoids the tendency of P to settle above or below the set point. Just like with P, too high an I term can lead to oscillation.

D: This is the “Future” parameter, and has the smallest impact on the behavior of the aircraft. In fact, some flight controllers leave it out entirely.  If P and I are approaching a set point too quickly, overshoot is likely to occur. D slows things down before the overshoot happens.

So why do multicopter pilots dread PID tuning?  Quite simply, it’s a tedious process. Couple a new pilot and an unproven aircraft with un-tuned PID values, and you have a recipe for frustration – and broken propellers. Things get even more complex when you consider the fact that there are at least 3 sets of PID variables to be tuned – Pitch, Roll, and Yaw. Some flight controllers now support multiple PID values depending on the style of flight. Want your plane or multicopter to fly around like a hotrod? You need a totally different set of PID values than a docile trainer craft. Rolf Bakke (KapteinKUK himself) made a video illustrating how multicopters behave when tuning PID values. You can easily see how a quad can go from “drunk” to “angry bee” with just a few value tweaks. All this is coming together with The Hackaday Testbed, which will help me in posting a few PID tuning videos of my own.

Hackaday Testbed Update

As for the testbed itself, it’s nearly complete! You can follow the progress on my Hackaday Projects Page. Most of the assembly has been relatively straightforward.   though of course there are always a few snags. It seems I always forget something when ordering up parts for coils-bada build. In this case it was 2.5mm banana plugs and motor mounting screws.

The Hobbyking motors attach to the frame with 3mm screws. The problem is that there really is no way to know how long the screws should be until you have the motors, mounting plates and drone frame on hand. I have a bunch of 3mm screws of various lengths, and thankfully there were enough screws of the correct length to mount the motors. Murphy is always at my side, as I accidentally grabbed a screw that was 1mm too long and, you guessed it, screwed right into the windings of the motor. Doh! Thankfully I had spares.

bullet-solderBullet connectors can be a real pain to solder. There are some jigs out there which help, but I’ve always found myself going back to the old “helping hands” alligator clips. Bullets tend to use lower gauge wire than we’re used to with regular electronics. 14, 12, even 8 gauge wires are used on R/C aircraft. A low power soldering iron with a surface mount tip just won’t cut it. Those irons just doesn’t have the thermal mass to get the connectors up to soldering temperature. This is one of those places where a decent 40 watt or better Weller iron (yes, the kind that plugs right in the wall) can be a godsend. I’m using an Metcal iron here, with a wide flat tip.

bullet-solder-2Bare bullet connectors and alligator clips can also create a problem – the metal clips create even more thermal mass. Years back an old-timer showed me a trick to handle this. Slip a piece of silicone R/C plane fuel tubing on the bullet, and then clip the helping hands onto the tube. The tube will act as insulation between the bullet and the clip. Silicone can easily withstand the temperatures of soldering. I’ve also used the silicone tube on the jaws themselves – though eventually the jaws will cut the soft tubing.

That’s about it for this edition Droning on! Until next time, keep ‘em flying!

Title photo credit Cyrus Abdollahi.

Congress Destroys A Hobby, FAA Gets The Blame

As ordered by the US Congress, the FAA is gearing up to set forth a standard for commercial UAVs, Unmanned Aerial Systems, and commercial drones operating in America’s airspace. While they’ve been dragging their feet, and the laws and rules for these commercial drones probably won’t be ready by 2015, that doesn’t mean the FAA can’t figure out what the rules are for model aircraft in the meantime.

This week, the FAA released its interpretation (PDF) of what model aircraft operators can and can’t do, and the news isn’t good: FPV flights with quadcopters and model airplanes are now effectively banned, an entire industry centered around manufacturing and selling FPV equipment and autopilots will be highly regulated, and a great YouTube channel could soon be breaking the law.

The FAA’s interpretation of what model aircraft can and cannot do, and to a larger extent, what model aircraft are comes from the FAA Modernization And Reform Act Of 2012 (PDF). While this law states the, “…Federal Aviation Administration may
not promulgate any rule or regulation regarding a model aircraft…” it defines model aircraft as, “an unmanned aircraft that is capable of sustained flight in the atmosphere; flown within visual line of sight of the person operating the aircraft; and flown for hobby or recreational purposes.” The FAA has concluded that anything not meeting this definition, for example, a remote controlled airplane with an FPV setup, or a camera, video Tx and Rx, and video goggles, is therefore not a model aircraft, and falls under the regulatory authority of the FAA.

In addition, the FAA spent a great deal of verbiage defining what, “hobby or recreational purposes” in regards to model aircraft are. A cited example of a realtor using a model aircraft to take videos of a property they are selling is listed as not a hobby or recreation, as is a farmer using a model aircraft to see if crops need water. Interestingly, receiving money for demonstrating aerobatics with a model aircraft is also not allowed under the proposed FAA guidelines, a rule that when broadly interpreted could mean uploading a video of yourself flying a model plane, uploading that to YouTube, and clicking the ‘monetize’ button could soon be against the law. This means the awesome folks at Flite Test could soon be out of a job.

The AMA, the Academy Of Model Aeronautics, and traditionally the organization that sets the ‘community-based set of safety guidelines’ referred to in every law dealing with model aircraft, are not happy with the FAA’s proposed rules (PDF). However, their objection is a breathless emotional appeal calls the proposed rules a, “a strict regulatory approach to the operation of model aircraft in the hands of our youth and elderly members.” Other than offering comments per the FAA rulemaking process there are, unfortunately, no possible legal objections to the proposed FAA rules, simply because the FAA is doing exactly what congress told them to do.

The FAA is simply interpreting the Modernization And Reform Act Of 2012 as any person would: FPV goggles interfere with the line of sight of an aircraft, thus anyone flying something via FPV goggles falls under the regulatory authority of the FAA. Flying over the horizon is obviously not line of sight, and therefore not a model aircraft. Flying a model aircraft for money is not a hobby or recreation, and if you’re surprised about this, you simply aren’t familiar with FAA rules about money, work, and person-sized aircraft.

While the proposed FAA rules are not yet in effect, and the FAA is seeking public comment on these rules, if passed there will, unfortunately, exactly two ways to fix this. The first is with a change in federal law to redefine what a model aircraft is. Here’s how to find your congresscritter, with the usual rules applying: campaign donations are better than in-person visits which are better than letters which are better than phone calls which are better than emails. They’ll also look up if you have voted in the last few elections.

If passed, the only other way these rules will align with the privileges model aircraft enthusiasts have enjoyed for decades is through a court ruling. The lawsuit objecting to these rules will most likely be filed by the AMA, and if these rules pass, a donation or membership wouldn’t be a bad idea.

Drones and Robots Come Out to Play at Sparkfun’s 6th Annual Autonomous Vehicle Competition

Sparkfun AVC 2014

Sparkfun Electronics held their 6th annual Autonomous Vehicle Competition last weekend, and this year was bigger than ever before. The action was at Boulder Reservoir in Colorado, but anyone could follow along (with a few technical difficulties) on the YouTube LiveStream. (Part 1), and (Part 2).

The story of the day was Team SHARC’s Troubled Child, which won the ground vehicle doping class. Rather than mess around with miniature cars, Team SHARC built their ‘bot out of a freaking Jeep, a 1986 Jeep Grand Wagoneer to be exact. Troubled Child had no problem getting around the course. One could say it carried the entire team. Literally – the rest of Team SHARC’s robots are riding along on top of Troubled Child in the picture up there.

There was also plenty of action in the aerial competition. Sir Crash-a-Lot was the first drone to find a watery doom at Boulder Reservoir. The last we saw of it on the stream, the team was looking for some divers.

Aircraft can not be hand launched at the AVC. Not a problem for rotary-winged vehicles, but this rule has led to some interesting solutions for fixed wing aircraft. The disguised “Team Falcon” showed up with an incredible compressed air launcher, which used a gallon water jug to fire their delta-winged plane to a clean run.  Team Karma550 wasn’t quite as lucky, with their helicopter crashing hard, and throwing up quite a bit of smoke.

We’re still waiting for more detailed results, but if you want the full scores, they are available on Sparkfun’s AVC scoreboard page.

Goliath: One Drone to Rule Them All


We see quadcopter projects all the time here on Hackaday, so it takes something special to get our attention. [Peter McCloud] has done just that with Goliath, a gas powered quadcopter he’s entered in The Hackaday Prize. By gas, we don’t mean a little glow fuel buzzer, We’re talking about a 30 horsepower V-twin lawnmower engine running good old-fashioned gasoline.

Multicopters powered by a single power source present a unique set of problems. Quadcopter propellers need to rotate in opposite directions to avoid the entire craft spinning due to torque action. With individual electric motors that’s as easy as swapping a couple of wires. Not so with a single rotating engine. [Peter] has accomplished this feat with a clever arrangement of single and double-sided belts.

Control is another issue. Generally, central powered multicopters use collective pitch, similar to a helicopter control system. [Peter] has decided to go with high-efficiency fixed pitch blades and a vane system for directional control. Much like hovercraft use vanes to steer, Goliath will use vanes to affect its attitude and yaw.

goliathPropThe propellers are works of art in their own right. [Peter] modeled the propellers in CAD using the principles of blade element theory, then used a Shopbot style CNC to carve them out of pink insulation foam. Styrofoam alone won’t withstand the 60 lbs each propeller will be supporting, so [Peter] plans to laminate the props in composite cloth. This is the similar to the way many full-scale helicopter rotor blades are assembled.

Goliath’s frame is constructed of Dexion style slotted steel angles, and we have to admit, at 240 lbs with engine, it seems like it’s going to be a heavy beast. Big enough to ride at least. Who knows… if the judges like it [Peter] may ride Goliath all the way to space!



SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

Autonomous Balloon Popping

Quadcopter drone for popping balloons

Taking on an autonomous vehicle challenge, [Randy] put together this drone which can locate and pop balloons. It’s been assembled for this year’s Sparkfun Autonomous Vehicle Competition, which will challenge entrants to locate and pop 99 luftbaloons red balloons without human intervention.

The main controller for this robot is the Pixhawk, which runs a modified version of the ArduCopter firmware. These modifications enable the Pixhawk to receive commands from an Odroid U3 computer module. The Odroid uses a webcam to take images, and then processes them using OpenCV. It tries to locate large red objects and fly towards them.

The vision processing and control code on the Odroid was developed using MAVProxy and Drone API. This allows for all the custom code to be developed using Python.

The Sparkfun AVC takes place tomorrow – June 21st in Boulder, Colorado. You can still register to spectate for free. We’re hoping [Randy]‘s drone is up to the task, and based on the video after the break, it should be able to complete this challenge.

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