Big Prop Cut in a Lipo, No Fireworks

What's a Watt? What's a Brushless? How many Watts are in a HorsePower? Help a clueless pilot out by posting your P=E*I Knowledge here!

Moderator: hbartel

Post Reply
Lee Liddle
Posts: 3330
Joined: Thu Jun 20, 2002 10:30 pm
Location: USA

Big Prop Cut in a Lipo, No Fireworks

Post by Lee Liddle »

There have been quite a few folks patiently waiting for a good fireworks show when the first lipo got a direct prop strike.

Sorry to dissapoint, but here is the result. The battery is a write off ($20), but no explosion, fire, smoke or even heat.


Image

The red area at the top of the batt is colored packing tape, used for identification. The black area under the red part is the inside of the top cell. Like I said, no smoke no fire no nothing. This may not be the case every time, but this is a real-world case.
Mike Gullikson
Posts: 50
Joined: Sat Nov 04, 2006 9:10 pm
Location: USA

Post by Mike Gullikson »

we have had a few of these lipo batteries get really hot and one catch fire on one club members work bench, he did have it stored in a clay pot for that reason thow, i don't know if it was being charged or just stored at the time, its a good reason why I will stay with the old batteries I have. no lipos for me
User avatar
o1moregil
Posts: 688
Joined: Tue Sep 27, 2005 4:12 pm
Location: Midland Texas

Post by o1moregil »

Lee, was there any damages to the rest of the equipment(due to shortage)? (esc, receiver, servos)
slam
Posts: 834
Joined: Wed Sep 05, 2001 8:14 pm
Location: USA

Post by slam »

lee

you shouldn't fly in front of other peoples props. those props could burst into flames at any time[}:)].

those darn master airscrews should have a warning on them about the possabily of spontaneous combustion.

lipos are the least of our worries[8D]

(the preceding was sarcasm, i don't believe there is a threat of the props bursting into flames, but don't think there is much threat of a lipo battery bursting into flames with a prop cut either)

slam
Lee Liddle
Posts: 3330
Joined: Thu Jun 20, 2002 10:30 pm
Location: USA

Post by Lee Liddle »

No other damage to anything as far as I know at this time. Haven`t tested the esc yet.
Lee Liddle
Posts: 3330
Joined: Thu Jun 20, 2002 10:30 pm
Location: USA

Post by Lee Liddle »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">we have had a few of these lipo batteries get really hot and one catch fire on one club members work bench, he did have it stored in a clay pot for that reason thow, i don't know if it was being charged or just stored at the time,<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Mike, I would imagine that the battery was being charged at the very least. I have heard of old people catching on fire while just laying around, but not lipos.[}:)]
Mike Gullikson
Posts: 50
Joined: Sat Nov 04, 2006 9:10 pm
Location: USA

Post by Mike Gullikson »

Thanks Lee, I was catching all that info from the club member trying to sell these clay pots to every one to store your batteries in, might just be a sale pitch at that.
jj
Posts: 729
Joined: Mon Jun 03, 2002 11:45 pm
Location: USA
Contact:

Post by jj »

I suggest that we don't publish any pictures showing what happens when a prop strike like that cuts open a hand or a finger. I've seen several of those and have a 30 year old scar to remind me to be careful. Also had an airplane burn up due to a backfire and subsequent invisible alcohol fire (invisible until the airframe caught fire itself).

We have managed to make one LiPo burn, and when it does burn it causes a bright, smokey but relatively contained fire. But if a LiPo gets cut in the air, the primary concern will be the direction and impact of the airplane, not the potential fire. Since we are talking about electrics you at least have an automatic throttle cut unlike an IC plane when a battery lead comes loose or is cut.

We need to be careful about the proper storage, handling and charging of LiPos, just like any of the other chemicals, motors and propellors we use in our hobby (have you read the label that they put on every MAS propellor).
User avatar
boiler
Posts: 3336
Joined: Wed Jan 01, 2003 8:16 pm
Location: Ohio
Contact:

Post by boiler »

jj, the other thing we have to be mindful of is that a downed nirto plane won't fire up and slash you with the prop when you retrieve it. Watch that throttle stick very carefully on retrieving an electric. Several have scars from the throttle stick getting bumped at the wrong time.
User avatar
Ed Kettler
Posts: 3437
Joined: Sat Dec 15, 2001 6:05 pm
Location: USA
Contact:

Post by Ed Kettler »

The cost of potential litigation accounts for over 50% of a typical light plane. There was a movement several years ago to place a sticker on all light planes stating that it would kill or maim you eventually, so fly at your own risk and don't sue us, we warned you!
jj
Posts: 729
Joined: Mon Jun 03, 2002 11:45 pm
Location: USA
Contact:

Post by jj »

The vast majority of light planes aren't ever invloved in avaition accidents, so they will most certainly not harm you unless there is a horrible lack of judgement applied. Unfortunately, just as with model aviation, this does occur some times.

Having built and certified an experimental airplane, as far as the FAA is concerned I am an aircraft manufacturer and hold that certificate. Fortunately, a number of years back our government realized that frivolous lawsuits would soon annihilate the light aircraft industry and so limited all manufacturer's liability to a maximum of 15 years. This is the only thing that keeps the insurance cost of a light airplane at 50-60% of the total price. It is also what has fueled the Experimental Airplane movement as it is silly to pay mostly for potential litigation rather than a good airframe. Also since I built my airplane, if I die in a crash, the odds of me suing myself are slim to none.

Having built my first R/C electric back in the late 80's prior to speed controllers having the "off" startup mode, I have been clipped by electric props. Fortunately back then the motors back then didn't have much bite to them.
Post Reply

Return to “All About Electrics”