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Best/Safe practice or wiring electricmotor - ESC- On off switch - Reciever


Bob Vaughan
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Best and most safe way is to never be in front of a live prop/electric motor/ESC

I have been pulled (and rightly so) by our safety officer for plugging a battery in through the prop arc.

I have used throttle cut and there are mechanical means available (plugs in battery/motor wires), but IMHO a good safe working practice is less likely to be skipped/forgotten about.

I have a number of models that have quirky start up methods (RX powered first, ESC's second etc) and thinking about it if I am not in a position to get hurt then its the best mitigation, rather than hoping this plug is in/out or that switch is off/on.

Just my view, others will have there's which are equally valid.

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I have a motor enable/disable switch on my transmitter together with a voice warning about its setting. On most of my models I don't bother with a battery isolation plug as some here advocate because connecting the battery is as easy and safe as having a plug which IMO is just another connection and a source of both extra resistance (slight) and potential failure.

On the one model in which battery connection has to be through the propeller arc because of way I did the conversion from glow to electric (my 58" DB Gypsy Moth) I have a safety plug in the motor, rather than the battery feed. That's a 4mm plug and socket on just one of the the 3 motor connections. That has the advantage of being both a protection and also allows all the other radio functions to be checked safely.

Geoff

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If you are using a BEC (separate from the ESC or built in) then a switch (yuck, horrible things) is unnecessary - just set up a throttle cut on your TX and have everything power up when you plug in the battery. The only reason for a switch on an electric model is if you have a separate power supply for your RX, which you can wire exactly as you do on any glider or IC powered model.

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I'm a strong advocate of safety switches on transmitters but please remember to treat them as an extra layer of precautions rather than rely on them.

Switches can fail, be knocked or simply mis-operated...we're all human (and we all bleed!)

Expect the unexpected.

Example:

Helping a clubmate last week with a new model which I'd just maidened for him. I observed that it could benefit from some aileron differential but it was set up with a Y lead. The model was powered up with the throttle locked? There were a couple of spare channels but it was a newish Futaba with different menus to when I'd had Futaba and the manual wasn't to hand. I found a setting for a 2 aileron wing and clicked on it, answering yes to the request for confirmation. Instant full throttle and several startled bystanders...

Luckily (I'd prefer to think of it as simple good practice) the model was restrained and everyone was behind the prop so no harm done. I (and the owner) was unaware that this simple change cleared the model memory and reset it to defaults...and as most of us know, Futaba throttles work in the opposite direction to that expected by most ESCs.

 

 

 

 

Edited By Martin Harris on 05/09/2019 22:08:31

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Make of this what you will, but I never use any form of 'safety system' on my electic models. By safety system I mean, isolator switch/link in the battery line or a cut out switch on the tranny. I restrain the larger models as I would an IC type and never go anywhere near the prop during the fitting of the battery and pre-flighting. I treat the system as potentially capable of going to WOT without warning at any time and behave accordingly. At the end of a flight, I'll ask a mate to hold the tranny and restrain the model, while I disconnect the battery.

Still got all my digits, in fact never had so much as a nick from a 'leccy prop. A few grazed knuckles from IC needle twiddling the old two-strokes back in the day though. Can never afford to allow one's concentration to wander, which ever way you deal with 'leccy.

 

 

Edited By Cuban8 on 06/09/2019 09:26:03

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I can't disagree with your philosophy - mine is very similar except I see the extra layer of security being useful as long as it isn't relied on. I'm always at pains to point out to clubmates that any safety device can fail for physical or human error reasons and to treat any electric model with the flight battery connected in exactly the same way that they would with an idling IC engine.

How many times have throttles been knocked open with transmitter straps, for instance? I've seen this with both electric and IC and a throttle lock prevents this happening.

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My Horus tx has a rotary switch top centre under the screen where it's all but impossible to knock it. I use this in position 1 to override the throttle setting it to -100, with audible warnings whenever the switch is moved. As I only fly electric now I have this set up on all models and templates. In days gone by I used a Deans socket in the battery line, fixed in the fuselage side where a shorting plug could be easily inserted and removed.

Cuban, I never used to bother with anything more than a sturdy restraint and common sense either but since I've got the facility to set up a throttle lock and I'm not so steady on my feet these days I like to lock the throttle while checking controls and moving models from pits to flightline. When I flying ic accidents happen even though we can see the props spinning around. With the static prop on an electric at low throttle it's even easier to slip up.

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My own "safety system", if I have to dignify it with such a term, is an external plug placed such that it can be conveniently reached from behind the prop' - breaking the positive lead between the LiPo and the ESC. So far, depending on the likely current that a particular set-up is likely to have to cope with the plugs have been a fuselage mounted XT60 with a hefty bit of copper wire soldered across it potted with epoxy (care with the installation - some XT60s need a bit of a tug to separate), or a pair of female 3.5mm or 4.0mm fuselage mounted plugs and (obvs!) a very short piece of wire with appropriate male plugs on each end to join them after you've switched on your Tx and never before. And keep 'em in your pocket until you're ready to fly., Far better than a bit of wire with a male plug waving about and a female plug waiting for a sparky kiss. Oh - and make up a couple of spare connectors of each size that live in your Tx case! I'm going to claim the above is fool proof (and so far it has been me proof) - not necessarily pretty but safe.

Edited By Old Geezer on 06/09/2019 17:07:32

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