Get to da choppa

11.01.2011 21:21

These little 3-channel IR-controlled indoor model helicopters seemed to be all the rage these holidays. They cost around 50 €, look quite solid with their metal frame and are electronically stabilized, which means you can fly them almost as if they were an RC car with an added Z axis.

3-channel IR-controlled indoor model helicopter

If they work correctly, that is. Needless to say, mine is defective. Just like most of the hi-tech stuff I get my hands on these days. It seems there's something wrong with the stabilization electronics. The helicopter mostly just wildly spins around as if the gyroscopic rotational sensor has a large offset. It's way beyond what is correctable with the trimmer on the remote control and a full left stick is just barely enough to stop the rotation. Sometimes though it will start to work correctly for a few moments giving me some hope that perhaps it's just a bad connection somewhere.

Circuit board inside micro RC helicopter

In search of that bad connection I took it apart. Which is surprisingly easy, since it is held together by screws and not glued together like most other such toys.

The electronic part of the helicopter is composed of a small single-cell 180 mAh lithium-ion polymer battery, a circuit board with a few transistors and an unmarked SMD chip, an IR detector and an angular velocity sensor (gyroscope).

Gyroscope element inside micro RC helicopter

The gyro used by this particular model seems to be Murata Gyrostar, a piezoelectric vibrating structure gyroscope. It's 8 x 4 mm in size!

So far I haven't found the cause of the problem. After I measured the output of the sensor on my desk it appeared to give the correct value for zero angular velocity and there are also no apparent bad connections. Testing that in flight is slightly more difficult, of course.

The datasheet for the Gyrostar warns about sensitivity to water condensation. Given that the steel parts inside of the remote control are a bit rusty it also seems likely that the whole thing was improperly stored somewhere.

Forgetting for a moment that the damn thing doesn't fly, I'm still astonished that all this can cost so little. Sure, the components are getting ever cheaper and anodized aluminum frames like this can be seen everywhere. But I see no way the 30-something tiny screws and hair-thin wires can be put together automatically. Just like for Pleo there must be non-trivial amount of manual work involved in manufacture.

For the sake of completeness, the helicopter I have is called Thunder Professional 2 by Modellbau Adam (their website is giving a PHP error ever since I first looked). But this info is mostly useless since I've seen this exact same model sold under a number of other names and I have no idea of its real manufacturer.

Posted by Tomaž | Categories: Life


Have you ever seen videos of work in chinese factories?

I stopped wondering about cost of manual work.

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