Hubsan X4 Cam

The Hubsan X4 H107L

       For awhile now I've really wanted to get into "FPV Flying", which refers to flying a remote controlled aircraft through a first person (onboard) view. This has only become possible relatively recently (at least, at a hobbyist budget) because of advancements in miniaturization, high frequency RF chipsets, and ever smaller batteries. Basically, we can thank the smartphone industry for making this new hobby a reality.

Most people do FPV from a quadcopter, as they are extremely agile and stable. I wanted to go this route myself, but was held back from spending the money on a ready to run setup due to the fact I had never flown a multi-rotor aircraft before. I didn't want to do my first flight on a ~$500 piece of equipment, which in all likelihood, was going to get intimately acquainted with the dirt in a matter of seconds.

Luckily, we've entered the era of almost disposably priced quadcopters which substantially lower the stress level of your first attempts to get airborne. After researching the various versions out there, I decided on the Hubsan X4 H107L.

At the time of this writing, the H107L can be had for around $40 USD from a direct-from-China retailer like Banggood.com. This comes with the customary multi-week shipping time, so if you want to get it in a reasonable amount of time, you may want to look to a retailer located in your own country (and expect to pay more). I got mine for about $60 on Amazon, and it arrived in two days.

While I'm certainly not yet qualified to compare this particular quadcopter to any other, I can say that it's extremely fun to fly. The standard control sensitivity is fairly docile for getting a hang of how a quad moves and operates, and putting it into the "Expert" control mode enables completely absurd speed and maneuverability once you're ready for it. Popular opinion seems to agree that this is one of the best cheap quads to start with, and my experience with it so far has definitely been along those lines.

Hobo Drone

Hubsan X4 Cam        Like I said, my goal is to start rolling some live video from above, and I thought a good first step might be to try and attach a camera to the Hubsan X4 to get a feel for what it's like using a quad as a video recording platform. Live video hardware small enough to fit on the Hubsan X4 does exist, but costs a bit more than I was willing to spend on an experiment like this; I'd rather spend the money on a proper FPV bird later on.

So I decided to get one of these cheap keychain "spy cams" that pop up on eBay for $8-$15 USD, and see if I could mount it to the quad well enough to record some in-flight video for later review. At a combined cost of no more than $60 USD, this seemed to be one of the cheapest ways to experiment with aerial photography and "drone" technology.

But as soon as I opened the box I realized there was a bit of a problem: the thing was fairly heavy. My scale put it at 14.82 grams.

OK, so ~15 grams might not seem heavy, but when you're talking about an aircraft smaller than a modern smartphone, that's a hell of a lot of weight to try and lug around. I tried strapping it to the bottom of the quad, but the thing could barely get off the ground at max throttle, let alone maneuver.

It was pretty clear I needed to give this thing a diet as quickly and easily as possible, as I really just wanted to get the thing up in the air and see what it looked like. So the most logical option was to just crack the case open and mount the bare PCB to the bottom of the quad. I was banking on the fact that the (relatively) thick plastic casing was a decent portion of the device's weight.

Opening up the case was a pleasantly simple affair. Two black screws on the back side come out, and the whole case hinges open on the side with the lens. There are then two smaller white screws which hold the PCB down into the other side of the case (where the buttons are).

Hubsan X4 Cam

This brought the camera's weight down to 9.85 grams, which I figured would at least allow me to takeoff. I grabbed some Kapton tape I had nearby and wrapped it around the quad and the camera PCB a few times to hold it on tightly to the bottom, trying to keep it as centered as possible to as not to offset the overall balance. The camera attached to the Hubsan X4, including both batteries, brought the total flight weight up to 46.25 grams. Still pretty heavy, but good enough for a test.

Hubsan X4 Cam

First Flight

       With my hacked together onboard camera, I took the Hubsan X4 outside and started climbing vertically to get some altitude. Performance seemed more or less unchanged when compared to flying without the camera (vertical speed is surely reduced, but in practice, it's hard to notice)...except when I tried to come back down. It seems like the extra weight on the bottom has some negative effect on the quad's automatic leveling function, as the whole craft starts to oscillate wildly while descending if you aren't very gentle.

So, how did it come out? Well, let's take a look...

That's...that's just terrible. I really hoped the video quality would be better, but I guess for $10, there isn't a whole lot I have to complain about. It's clear enough to make out the difference between a building and a tree, but beyond that, it's pretty helpless.

Other than looking terrible, the one major annoyance of this setup is that the buttons to operate the camera are located on the top of the PCB, which means that I had to mount it upside down on the bottom of the quad to operate it. Naturally, this makes all the video recorded with the quad upside-down as well.

Using the very straight-forward Avidemux, I was easily able to not only rotate the video back around the right way, but also get rid of the terrible audio track (imagine holding your head against a tin-can full of angry bees if you'd like to get an idea of what it was like). The only thing I don't like about this (and what somebody called me on almost immediately), is that it leaves the now inverted timestamp in the upper corner of the video. Naturally there's no option to just turn the timestamp off.

Looking Ahead

       Honestly, seeing how poor the video came out largely put me off from doing many more flights with this camera to begin with, but then I started noticing some other annoying traits which really drove me nuts.

Such as the fact that, since the camera is now the lowest part of the quad (extending below the "landing pads" under each motor), it takes the brunt of the energy during landings. Unfortunately, this little camera seems to particularly dislike being jostled around, as even a fairly easy landing seems enough to force the camera to reboot (deleting the video that was currently recording, naturally).

The problems with this setup have been pushing me towards getting a larger quad where it's not quite as hard to add additional equipment to the craft. That said, the Hubsan X4 is a blast to fly and does manage to get into some hard-to-reach places.

So I may end up revisiting this experiment with a little less haphazard attitude in the future. Rigging up some light-weight landing skids would take the weight of landing off of the camera itself, and hopefully limit how many videos I lose. I'd also like to rig something up where I can drive the camera off of the quad's main battery, which would take a big chunk of the flying weight off.