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wanna see the inside of a lipo?

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E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

wanna see the inside of a lipo?

Old 10-21-2005, 06:45 PM
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dfalcon
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Default wanna see the inside of a lipo?

I finished building my first kit (Mini Telemaster) at the end of September, and tonight was its second flight. I'm not quite sure why yet, but it turns right better than it turns left. Any way, I had flown around for about 10 minutes and was ready to land. The first approach lined up good with good altitude and speed, but it started drifting right and I couldn't correct in time (see above). So I gave power and a little right rudder to go around. Now it doesn't want to turn left or straighten out at all! The least I can say is it's still gainin altitude. It whips violently upside-down and speeds into a port-a-potty before I can settle it down and bring it peacefully to earth. The wing, very close to the fuselage, struck the john and the plane came to such a sudden stop that the 11.1V 2000mAh battery (was secured with a strip of velcro) flew forward and knocked the firewall cleanly off.
As I started the walk of shame, a huge white cloud sprung from the crash site. I didn't know at the time that the battery flew clear of the rest of the plane, and so I thought that my hours of building were going up in smoke. When I finally got to the wreckage, I first saw that my plane was still in one remarkable piece (only a dented LE on the wing and a missing firewall and motor), and I saw the battery[X(]. I knew what these are capable of, but it's still amazing to see. One of the cells was completely incinerated. I kicked the remains, and saw a spark come from the middle of one of the remaining cells, then another large white cloud. These are the two cells, what's left anyway. I figured the last cell was better off staying were it was in the gravel, until tomorrow anyway.
Luckily, the only damage was to my plane and the lost battery. I was flying in a new residential subdivision nearby where the roads are paved, but they have only recently begun to build the foundations of a few houses. Not much potential for damage except a possible burned up port-a-potty. After having some time to recall how things went, I must be exceptionally skilled to hit the only structure around.
Take care and continue to give lipo's the respect they deserve.
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Old 10-24-2005, 09:40 AM
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Matt Kirsch
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Default RE: wanna see the inside of a lipo?

I think we can definitively say what caused the fire, at least. When you use a LiPoly as a battering ram like that, they do tend to get a little bit angry about it

Glad to hear the plane will survive to fly another day.

How was/is the rudder throw? Equal to both sides? How about right and down thrust? Maybe too much? I've got to believe it's something simple like that, because if it were something like prop torque, it would turn better to the LEFT because the prop torque is trying to roll the plane to the left.
Old 10-27-2005, 10:59 PM
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Default RE: wanna see the inside of a lipo?

Had a similar thing happen with a NiMH pack, just not quite as dramatic. I crashed my Mini Super Sportster, and in my disgust (and ignorance), I failed to chop the throttle. Funny about electric motors...if they've got juice, they keep the torque on even if the shaft is stopped. The motor, broken loose from the mounts, twisted up the wires to the point that a short resulted; this resulted in one cooked 8 cell pack and a totally cremated ESC. I never knew until then that an electric plane could produce classic smoking wreckage. Live and learn.
Old 10-31-2005, 03:29 PM
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Default RE: wanna see the inside of a lipo?

the prop torque thing came up if i applied power too quickly--the plane would spin quickly to the left. thinking back i guess i could have given quick bursts of throttle to oppose the right turning tendency. it had a little downthrust, but none to either side. i set up the rudder as best i could; the control rod was perpendicular to the servo arm at neutral, and deflections measured 1/2" both ways.
both wing halves rested flat on a couter-top, even after heat shrinking the covering. i don't know of any other methods to look for a warped wing.
i built the tail feathers as close to perpendicular as i could, so i'm still clueless about the right turning being better than the other way.
what i thought on the first flight was that the cheap gws naro was glitching. i could hold the stick all the way to the left with no result, then return it to neutral and quickly snap it back to the left and the plane would respond. then it did the same thing with a hitec servo.
Old 11-18-2005, 07:17 PM
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Default RE: wanna see the inside of a lipo?

A while ago I picked up the Ni-Mh pack from my stryker and was holding it in my hand walking back, and suddenly I felt my finger getting burnt from the battery. Luckily it wasn't serious, but I realized when I looked at the battery that it had short circuted and burnt through the cover! It was pretty cooked around where it had burnt through, and so was my finger where it got burned, which looked all black and brown before I washed it off. I'm guessing that during the crash, the batteries leads had pulled out and caught each other for a moment. Then when I picked it up I managed not to notice it since it was on the bottom. Always be careful with all batteries!

On the plus side, that same battery had (earlier) decided to "eject" from an older plane in a death spiral at about 50', hit the ground, bounced, and was still useable. Even one of the batteries I'm using now has fallen out of the plane in midair, due to a faulty battery hatch, and still is perfectly fine!
Old 11-21-2005, 12:15 PM
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Default RE: wanna see the inside of a lipo?

I still think the post would have been much better if resulting Li-Po fire would have lit the port-a-potty up! Nothing like a pic of a smoking john to get a rise out of everyone. :P

-syn
Old 11-21-2005, 02:58 PM
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Dezynco
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Default RE: wanna see the inside of a lipo?

I'll tell my story! I was flying a ModelTech Magic with a 12-cell nicad pack and the BEC on my speed controller went bad! The plane climbed straight up for about 300 feet, then quit and fell like a dead duck! NO CONTROL AT ALL! It seemed like it fell for a minute! When it hit the ground, that big ole' battery pack went through the firewall and shorted out, setting the grass and my plane on fire! Had to run over and stomp it out![X(]
Old 11-21-2005, 03:02 PM
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Default RE: wanna see the inside of a lipo?

The port-a-potty thing almost happened, syn. The pack was only 2 or 3 feet away from it. That would be a picture I'd almost be proud to show. [sm=lol.gif]
Old 11-21-2005, 06:23 PM
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Default RE: wanna see the inside of a lipo?

roguespear,
On the turning issue, check the rudder pushrod for stiffness by applying a load to the rudder with your finger. Do this with the servo powered up. Many times the pushrod will bend when in compression but be fine in tension, so you get better turning in one direction. It may need reinforcing (use a thin carbon tube or just use some thread and spiral wrap something to stiffen it up)


RE: wanna see the inside of a lipo? Wanna see the inside of a burned Explorer?[X(]

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