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Old Mar 27, 2012, 02:16 PM
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MikeontheBike's Avatar
sacramento. ca
Joined Dec 2010
105 Posts
Alert
noticing dangerous body, hand, and arm positions when plugging in flight battery

I just built a dw foamies 48" yak 55m and as I was installing the motor and took the apc 12x6 prop out of the bag I had a flashback to about 13 years ago.

I got eaten by an apc 11x6 prop back then on a nitro model.

I was flying full throttle and glow plug burned out, I dead stick landed, saw the clock and knew I needed to get to work, I took the wing off, took fuel line off the carb, drained the tank, installed a new glow plug to dry start it a few times to burn out any unburnt fuel so I could add some after run oil, AND I NEVER PULLED THE STICK OFF FULL THROTTLE.

The plane started up wide open for a few seconds, huge thrust, my hand slipped down the oily fuselage and the prop went right into my left knee.....SLASH, SLASH SLASH all the way to the bone then kapoot the engine used up it's burst of fuel and died, if the fuel line was on and it didn't die, then I might have!

I put a belt around my leg to reduce the bleeding and got rushed to the ER. over 50 stitches later I was good to go after a couple months of healing.


ALL of that being said I have been watching a lot of large 3d foamie videos lately up to purchasing my yak and have still been watching them in anticipation of being able to fly mine (it's built, weathers bad now)

Anyways I've been noticing that because the way these things are set up with battery locations and such that I have been seeing SO MANY PEOPLE reaching right through the prop path when plugging in their batteries. Mechanical things fail as well as electronic things fail.

PLEASE EVERYBODY STAY OUT OF YOUR PROP SPINNING PATH OR PROP CIRCLE WHEN POWERING UP YOUR ELECTRIC MODELS

I don't want to imagine what could happen if a powerful brushless motor started up wide open with someone in the prop path.

Just trying to give everybody something to think about from my misfortune before with the nitros and from my observation of all the unsafe electric practices I've been seeing. I don't want anybody to harm themselves. It's no fun when skin and blood are flying instead of your plane
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Last edited by MikeontheBike; Mar 27, 2012 at 02:28 PM.
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Old Mar 27, 2012, 02:45 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
13,443 Posts
There are some 'fail safes' built into ESC's, but they cannot make them idiot proof.

Sadly we can still produce better and better idiots

Where in the past you were very unlikely to start a glow motor in the house, (divorce can be expensive, the rath of your mum could be worse). With electric power it's too easy to leave the prop on while just 'checking the servos'.
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Old Mar 27, 2012, 10:09 PM
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Glacier Girl's Avatar
USA, FL, Lakeland
Joined Jan 2010
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Easy fix, install a kill switch. Something as simple as a Deans connector with the terminals connected that has to be plugged in to power the plane, after the pack is plugged in.

I do it on any of my birds that say have to have the pack installed and then a wing put on.
I don't like the idea of a live bird sitting there. When I'm ready to fly I install the plug and now the bird is ready to go.
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Old Mar 27, 2012, 10:26 PM
Registered User
Taiwan, 北市
Joined Dec 2010
1,215 Posts
Very good point, Mikeonthebike !

Thank you a lot for such kind and useful reminder.
I always pull down throttle stick first, then turn on Tx, and then connect battery pack with ESC. Fortunately, the modern ESC's are normally designed to activate while applying idle on throttle. But I still apply my way no matter what ESC I use.

I used to apply idle for starting my glow engines unless it's an engine on control - line airplane.

Chen
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Old Mar 28, 2012, 06:31 AM
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Kingston, Canada
Joined Jun 2004
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I use one somewhat like Glacier Girls. Batts are installed permanently so this mounts on the side at the back of the cowl near the top. Well away from the 22 in. meat slicer.
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Old Mar 28, 2012, 09:14 AM
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H2SO4's Avatar
Australia, New South Wales, Sydney
Joined Jan 2011
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A very good reminder. Thank you MikeontheBike et al.

I'm trying to always play it safe by dividing the world into two halves of equal size whenever the battery is physically in an aircraft:

A) Everything in front of the prop's plane of rotation.
B) Everything behind it.

Obviously, for safety's sake it's best to remain in hemisphere "B".

In my limited experience the real enemy is the Tx neck strap. It is just too easy to accidentally catch the throttle stick either on the neck strap itself or while the Tx is being swung about courtesy of the strap. That's also when my face and upper body are most likely to be poised over the plane, connecting the battery and potentially intersecting with the prop.

I like using a Tx strap though, and this freebie which HK sent as a gift for being such a willing customer has a feature that I can't praise highly enough - that quick-disconnect buckle in the middle:

http://www.hobbyking.com/hobbyking/s...dProduct=11982

(They're $0.99. I'm not a shill, but I seriously don't understand how that's possible.)

My battery insertion/changing routine:

1) Disconnect the Tx neck strap via that buckle.
2) Power up the Tx with the throttle stick at 30% or so.
3) Leave the Tx on the ground behind the airplane, at least 1m away, or 2m for luck.
4) Connect the battery while doing everything possible to keep all body parts behind the prop's rotation plane.
5) The ESC will now start singing its "Throttle not at 0%!" warning.
6) Secure the canopy and walk back to pick up the Tx.
7) Return the throttle stick to the 0% position.
8) It now takes several seconds for the ESC to arm, and it'll do so with a very specific series of beeps which most of us could recognise anywhere (lovely sound! ).
9) Pre-flight check, still standing behind the airplane and preferably to one side as well.
10) Let 'er rip.

I prefer to purposefully prevent the ESC from arming because the beeps and the delay that's necessary to arm it give me those cruicial two or three seconds to get the hell out of the way if I or somebody else should somehow punch the throttle stick before I'm clear of the prop.

Naturally, I can't be confident that all ESCs will exhibit this arming delay behaviour, so please test yours carefully before relying on the results.
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Old Mar 28, 2012, 09:55 AM
'tis nothing
shunyata's Avatar
United States, CA, Napa
Joined Dec 2011
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Quote:
Originally Posted by H2SO4 View Post
A very good reminder. Thank you MikeontheBike et al.
+1, yes, thank you!

Quote:
Originally Posted by H2SO4 View Post
I like using a Tx strap though, and this freebie which HK sent as a gift for being such a willing customer has a feature that I can't praise highly enough - that quick-disconnect buckle in the middle:

http://www.hobbyking.com/hobbyking/s...dProduct=11982

(They're $0.99. I'm not a shill, but I seriously don't understand how that's possible.)
The price? It's a branding expense. You get the privilege of promoting their brand on your dime... er, dollar.
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Old Mar 28, 2012, 11:10 AM
Lover of fine cheeses
United States, IN, Mauckport
Joined Jan 2012
141 Posts
I've had an experience in this same area. I was working (read: poking around) with my super cub. Checking servo line-up, and I bumped the TX throttle stick. SC jumps off of the kitchen table. Ended up costing me a prop and tail section. I didn't get hurt, but the floor got a chunk of linoleum taken out.
Lesson learned...at least mine didn't cost any blood!
Peace
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Old Mar 28, 2012, 11:52 AM
'tis nothing
shunyata's Avatar
United States, CA, Napa
Joined Dec 2011
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One thing to never do. With a powered-up plane and your Futaba fasst TX, never do a model reset. The entire plane will go nuts. Full throttle, too. Don't ask me how I know.
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Old Mar 28, 2012, 03:56 PM
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United Kingdom, England, Bristol
Joined Dec 2011
628 Posts
I haven't really worked it out fully yet, but my son's Dynam RTF TX seems to have a brilliant failsafe built-in (it might be something intended for a completely different purpose).

His motor will not respond to any throttle stick movement or start position until an unmarked switch is flicked on and off.
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Old Mar 28, 2012, 04:40 PM
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dedStik's Avatar
United States, VA, Virginia Beach
Joined Feb 2012
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I do it old school, I have an on/off button on the side of the plane well out of reach of the prop.
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Old Mar 28, 2012, 05:24 PM
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sacramento. ca
Joined Dec 2010
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I'm glad people are commenting on this thread with their techniques for safety!!! It will allow new fliers to understand some of the dangers involved, and give them ways to safe guard against the same problems.

I too have taken some knowledge away from this thread. I like the idea of a power switch or another battery plug acting as a fuse to guarantee it's a dead plane until you are ready to go hot
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Old Mar 28, 2012, 05:49 PM
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MikeontheBike's Avatar
sacramento. ca
Joined Dec 2010
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Quote:
Originally Posted by Glacier Girl View Post
Easy fix, install a kill switch. Something as simple as a Deans connector with the terminals connected that has to be plugged in to power the plane, after the pack is plugged in

I do it on any of my birds that say have to have the pack installed and then a wing put on.
I don't like the idea of a live bird sitting there. When I'm ready to fly I install the plug and now the bird is ready to go.
Great idea!!!

Quote:
Originally Posted by flypaper 2 View Post
I use one somewhat like Glacier Girls. Batts are installed permanently so this mounts on the side at the back of the cowl near the top. Well away from the 22 in. meat slicer.
I like both of your ideas, nice plane by the way
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Old Mar 28, 2012, 07:41 PM
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United States, CA, San Diego
Joined Jun 2007
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Thanks for all the tips! Here's another lesson I heard of:

A guy turned on his radio to change models to the next plane he will fly, he was squatting down to the plane next to the table at the field, and suddenly, one of his models at the table came alive and flew towards his face! He was able to block it with his forearm (Which paid a heavy price...) and then the model fell from his arm, chewed up his other plane, and then his leg before things got under control.

Turns out, he didn't unplug the battery on the model he flew earlier, so it was still on, and the ESC already armed since it had already flown, so when he turned his transmitter on it immediately responded to the throttle which wasn't off...

Back to the basics, transmitter on first, off last.
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Old Mar 28, 2012, 07:57 PM
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H2SO4's Avatar
Australia, New South Wales, Sydney
Joined Jan 2011
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Quote:
Originally Posted by xmech2k View Post
Back to the basics, transmitter on first, off last.
I'd like to understand the reasons and advantages for switching the Tx off last. Right now, I do it the other way - Tx off first as soon as the plane has come to a standstill - but that's quite possibly incorrect and I'd appreciate some pointers.

My reasoning is that the speed controller (ESC) is nowadays no longer mechanical. It remains armed only while the Rx is receiving a signal from the Tx, and by that logic deactivating the Tx is in some ways analogous to a kill switch on the plane.

What I'm mostly trying to avoid is that scenario where I'm rummaging round near the plane's innards - and its prop! - while a powered-up Tx is dangling off my neck, ready for the throttle stick to accidentally bump into something. Once the Tx is deactivated I feel much safer reaching in to disconnect the battery.
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