Having decided to use an electric helicopter instead of a sailplane, here's how I failed (again) with that one:
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| the basic "Piccolo" setup in flight |
I had the Piccolo assembled and buzzing in the living room a mere 30 hours after coming home with that tiny cardboard box. However, I did things very carefully and didn't actually let it leave the ground before I had made large training skids that prevented it from tipping over. Within a few minutes of actual hovering practice the tail motor died and I replaced it with a cheaper, but more durable DirectDrive tail.
Over the next four weeks I practised hovering in the living room and in the street. I ordered several small replacement and "tuning" parts from e-heli-shop
and felt things were getting better with some improved swashplate mounting parts and a new (and actually straight) main rotor steel shaft.
Five weeks after assembly and with a few "jumps" to 1.5 meters on the safe side of the timeline, I removed the training skids ... and then the little insect really started flying!
The picture to the right was taken by Jockal nearly six weeks after assembly, when I flew the Piccolo in his garden. By this time I had learned to do relatively stable hovering and point landing, and had done "nonstop flights" up to about three minutes and ascended to around 10 meters. Still, I always kept the tail of the helicopter towards me, trying to avoid any confusing situations that could lead to crashes. Hovering with the chopper's tail pointing away from me, pirouettes, and flying in full circles are things I'll have to learn sometime, maybe with a simulator...
But since then the original 700mAh NiMH flight battery has lost so much of its capacity that it lasts for only about half a minute of mid-air hovering after charging for six hours, which isn't at all what it should be - so now it's "Tuning time".
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| time for some improvements (this is the old config) |
In September 2004, after my bicycle tour, I completely disassembled the Piccolo again and ordered lots of stuff for a complete refurbishment, including a Kokam Lithium-Polymer battery (1500mAh, 3S) and a decent charger, a Castle Creations Phoenix 10 brushless controller, and a brushless motor - actually a motor from a CD-ROM drive modified by "TiggerVater" from the Ikarus BBS. I also got a freewheel for the main motor (another one of those amazing high-quality items from "Agrumi"). But with that alone, it wouldn't deserve the name widiCopter...
As I said I would, I also bought a small wireless camera (ZT-811T from ZTV Electronics) on ebay which, after removing the bulky plug (with integrated 9V-to-5V reduction IC), now weighs only 10 grams and is ready to connect to the Piccoboard's BEC (like a servo motor). The color (or daytime color infrared! yesss!) video transmission can then be recorded on the ground by my Sony Vaio notebook, for which I also got a USB video digitizer (Pinnacle Linx USB plus, also bought on ebay) - and the camera's receiver is powered by the NiMH accumulator retired from the Piccolo.
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| two frames from the first camera flight |
After the above upgrades were installed, I actually did one (and only one) outside flight with the small camera on board. During that flight and some more flights without the camera, the helicopter repeatedly and without any obvious reason switched off its main motor in mid-air and crashed down on the street. While not much damage was caused, I felt unsure and did some testing which revealed that I had only a safe remote control range of about 10 meters before the main motor would suddenly stop, then start again and keep running even though I set the throttle to zero. The only way to stop it would be to disconnect the battery for a few seconds.
This was definitely not OK. First I blamed a small battery switch I had built in for more convenient activation/deactivation of the entire system, but after I removed it the malfunction occured again. Then someone suggested my antenna mounting was very bad (mostly parallel to conductive carbon struts) and I tried again with a freely hanging antenna - guess what, the problem still persisted.
Finally I disconnected the new motor, its controller and the new battery, and tried again with the old components ... no more problems, radio range above 100 meters with some cars in the sightline!
Knowing that, I said, let's try with only the new battery... and connected it to the Piccoboard with reversed polarity. Poof! went the main motor Schottky diode, emitting a small puff of smoke and a very bad smell, and some time later I realized the tail motor FET had been killed too. With a lot of help from the guys at the Ikarus BBS I figured out it would be much cheaper - while very well feasible - to repair the Piccoboard myself instead of returning it for repair.
I actually managed to replace the tail motor FET and both Schottky diodes with a new, more precise soldering pen and the Piccoboard is working normally again (at a cost of 82 cents, compared to about EUR 40 Ikarus would have charged me!). The next idea I have for solving my range problem is wrapping the ESC (brushless controller) and the Piccoboard's receiver in aluminium foil - it has been suggested that noise from the ESC may be causing the receiver to fail.
However, there was some mechanical damage to the helicopter as well. The left skid had lost its strut connectors, and two of the landing gear struts were broken. I decided to remove the other two struts, too, and make an entirely new landing gear for it. I pictured something like the "Pixelito" chassis which consisted of one single steel wire bent around in a very decorative and functional way - however the Pixelito weighs less than 10 grams, compared to the Piccolo at about 300 grams. My attempt to roughly duplicate the construction failed - I just couldn't get the wire bent in exactly the way I wanted it to look like, and it didn't get nearly as precise as it would have had to be, symmetric and all that...
In November, I got a new Delrin/aluminium landing gear which increased the amount of "Agrumification" on my helicopter even more and appears to be nearly indestructible.
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| The fully "pimped" Piccolo - still not much fun... |
Over the winter I didn't do anything about the helicopter as I was busy studying, taking exams and generally thinking of other stuff. The page about the RCSIR project details on that "other stuff" :-).
In February, I dusted off the helicopter and realized that the second servo motor was dead and getting the Piccoboard nervous. Luckily I had a spare servo at hand. To resolve some balancing and battery mounting issues, I constructed a holder for the Piccoboard on the tail boom and moved some of the other parts as well. Further testing showed no more problems except a slightly twitching tail, but I didn't bother checking the radio range and stuff, just hovered around in the living room for a while. Just once I managed to actually "empty" the Lithium polymer battery!
Somehow my enthusiasm about the project was gone, mostly due to all those electric, radio, and mechanic problems involved, and also because I didn't see any way I would do serious aerial imaging with such a delicate and hard to control device.
But the point I really got discouraged - about the helicopter, that is - was when I caught TV reports of a four-propeller, highly stable and "unbreakable" toy aircraft: the Silverlit R/C X-UFO due to appear in European stores in April 2005.
By mid-2006 I had sold most of the Piccolo's parts - so it no longer exists :-/
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(c) 2004-2007 by dAWiDi@ubahnsound. part of dawidi's widicam.net | 
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