|Sometimes it hurts!|
This article is just a collection of a few of my personal FAIL stories where the failure was somewhat unusual and not necessarily related to the pilots "dumb thumbs".
ENJOY and LAUGH or LEARN!
In my search for the lightest possible Lipo packs I found what I hoped would be a great find, Zippy Compact series packs. These were 50 to 100 grams lighter than they're counterparts without a reduction in capacity and they were slightly smaller.
I bought two of these first in a 25C, 2700/3S configuration for my FPV plane and in this application they worked great (still working). I then bought two 35C 4000/4S packs for my Disco Quad and unfortunately found them to be not so great in terms of build quality. The first pack, shown below, had eight cycles on it when all of a sudden it would not power the Quad up. When I put a cell checker on the balance port it showed the usual 96% but when I put a volt meter on the battery leads, nothing except when I squeezed the top of the battery.
The pack, when mounted had no stress on the wires and the maximum draw was 48A at 100% throttle (12C) which I never used. The pack never came down warm. Fortunately, I discovered this on the bench and not in the air.
And the second pack?
The second pack fared much better giving me over 80 cycles. I did wrap the wires to the pack side with a rubber band so the internal connection would see very little movement. Unfortunately, the exact same failure occurred. So, the question on this FAIL is, was this a bad batch or just poor quality overall?
I no longer buy the compact series...
|Connections are important!|
If you have played around with multi-rotors then you have likely heard of or seen this before. Many of the less expensive Chinese motors come with poorly soldered connectors which will eventually fail and this means an immediate crash for a quad. Generally it is always a good idea to re-solder these to avoid this problem.
With that said, the connectors shown below were re-soldered and gave me great service on three different quads. The failure came on using these on a new Y6 project. While pulling the connectors apart the connectors simply pulled off the wires. On really close inspection I can see the wires were poorly stripped nicking the wire and weakening it. So, with this new knowledge I will cut and re-strip motor wires before re-soldering for double protection.
|The cause of the quad flip!|
Sometimes you see a new shiny plane you just must have! This was the case when I first saw the Wattage Extra 330L back in 2003. It was a 32" bird with a wicked Brushed Cobalt 400 motor. The plane was heavy (to say the least) at more than 30.2oz (860gr) with the stock motor and recommended 8 cell NiCad pack. The first attempts to fly this bird were done from a high school track and it never had enough power to get off the ground. To make a long story short it would not fly until I put in one of those "new" LiPoly batteries which cut the weight by nearly 5oz and pumped the voltage up by two volts.
The picture was after my first hand launch attempt off of a fairly high hill.
The lesson here is obvious; no matter how swoopy that plane looks, do the research!
|Some Airframes simply don't fly well (or at all)|
This one actually is not mine but a local flyer from my club here near Seattle. And it wasn't the battery that failed but the picture was so cool, I just had to include it here.
This was a 4 cell lipo in a FunJet that augured straight in from approximately 80 feet. The pilot didn't know why but he had a control lock-out when it was pointed straight down with, of course, full throttle. It was completely obliterated and the amazing bit is the lack of fire or smoke from the lipo.
|Really, NO SMOKE!|
This is actually two fails in one! This occurred on the (first) maiden flight of my Aerobeez 57" Extra 330-50EP. I was four minutes into the flight when the Castle ICE75 ESC let all the smoke out. That was the first fail, the second fail was that I hadn't equipped the Spektrum RX with the recommended capacitor which protects against brown-outs in the older DSM receivers.
This was also during a low point in Castle products when they earned the nickname "Castle Creamations". They were very kind and replaced the ESC with a new version but the Airplane was a total loss with 4:20 of flight time.
|What's that aroma?!|
We've all done it. Rushed into a project or a task, taking short-cuts "to save time".
In this case I was uploading new firmware into the Naza V1 controller on my Disco Quad which had the props on and was fully powered up. Really dumb. Turns out that in the earlier versions of the firmware the throttle would go to full while the unit was re-booting. I had to duck fast and block the Quad from coming into my face. Man those Graupner props are sharp!
I did contact DJI and ask them to please consider adding a warning about props on when doing an upgrade and surprise, surprise, they did this to the next release. I have also added a way to power the flight controller without powering up the ESC's so I'm double covered with this and the props off.
Be careful out there and don't rush!
|Think about it!|
I know, doesn't look like a servo fail...
Actually, the servo didn't fail, it was sized incorrectly. The plane is a 48" Precision Aerobatics Extra 260 which is a super lightweight (32oz or 910g) high performance 3D air-frame. It was built with all the stock components except the servos which were a Bluebird 10gr. I instead used Hitec HS55's because I had a set and had read they worked just fine in this plane.
What happened was a bit strange. I was coming out of a moderate dive pulling level with no more than 40% power when as the plane leveled, it shuddered badly and then flew rubbery (best way to describe it). I immediately landed and on inspection the wing was all broken up inside up to the 4th rib. It was a mystery for sure.
The mystery was solved when I contacted PA in Australia and was told they had seen this before and that it is caused by aileron servos which are too weak and cause a high oscillation in the ailerons which tears the wing up. They were very nice and sent me a new wing (foc!) and I purchased a set of HS65MG's as they were out of the Bluebirds.
|Component selection, it's important...|
More to come...I'm Sure :)