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Why no safety switch on motors??

Old 08-30-2010, 06:46 AM
  #26  
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Rubber band the throttle on low until you are ready fly. Simple, easy, and it works.
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Old 08-30-2010, 10:19 AM
  #27  
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Originally Posted by mclarkson View Post


I'm not arguing against any of that.

Think of it like a safety on a gun, though. Yes you should never put your finger on the trigger until the sights are on the target, check if it's loaded, etc. etc. etc. but guns have safeties on them, anyway.
So do electric models - the batteries are on plugs, they're not permanently fitted .

BTW the last serious injury I saw was with an ESC that had a switch fitted. It was switched off but a fault still started the motor. The owner was injured because he was handling the plane carelessly...he just knew it was completely safe because the switch was off .

With rotating blades and a lot of energy there's no such thing as completely safe !

Steve
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Old 08-30-2010, 09:35 PM
  #28  
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Originally Posted by slipstick View Post
So do electric models - the batteries are on plugs, they're not permanently fitted .

BTW the last serious injury I saw was with an ESC that had a switch fitted. It was switched off but a fault still started the motor. The owner was injured because he was handling the plane carelessly...he just knew it was completely safe because the switch was off .

With rotating blades and a lot of energy there's no such thing as completely safe !

Steve
Yeah, I have several of those "Gobrushless" motors, that run about 120 watts or so. One of them split my finger nail with the prop some 5 years ago. (Can that little motor hurt anyone? Yep ) Took three months for that fingernail to get back to normal.
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Old 08-31-2010, 09:30 PM
  #29  
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Default "Plug" not "Switch"

Originally Posted by Henry111 View Post
On my larger airplanes I always install a safety switch available from Atlanta Hobbies. It has an inlet located on the outside of the fuselage. To arm, a plug is inserted, removed to disarm. Since I also use a separate RX pack, there are two switches on the outside of the airplane. To check the controls I throw the RX pack switch. The motor is not armed. When ready to fly I insert the safety plug to arm the motor.
By the way, the safety switch weighs only one oz, not even a factor on larger airplanes.
On smaller airplanes were I use BEC instead of an RX pack, I find that Nitro Blast's suggestion is the best. When you want to test the controls without arming the motor just keep an RX pack handy and plug it into the receiver.
I probably should not have referred to it as a "Switch." It is actually a plug. When you remove it, the current is disconnected totally. In the photo on the left you are looking at the bottom of the hatch on our Midget Mustang 60. On the right is an exterior shot of the hatch with the plug in place. When we arrive at the flight line we plug it in. Before leaving the flight line we pull it out.
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Old 08-31-2010, 10:09 PM
  #30  
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Originally Posted by Henry111 View Post
I probably should not have referred to it as a "Switch." It is actually a plug. When you remove it, the current is disconnected totally. In the photo on the left you are looking at the bottom of the hatch on our Midget Mustang 60. On the right is an exterior shot of the hatch with the plug in place. When we arrive at the flight line we plug it in. Before leaving the flight line we pull it out.
I am an electrician and we call some switches "Disconnects" The term is used mostly in the NEC codebook. A switch is mostly used to control a "Luminaire" (Codebooks term for light fixture).
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Old 09-01-2010, 04:25 AM
  #31  
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Hey Pete, thank you so much for clearing my head on that very technical and important point. The next time an RC electrical question comes up let's all be sure to check the NEC Code Book.
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Old 09-01-2010, 04:39 AM
  #32  
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henry,i like the picture of that plug. it shows we don't need to add so much extra wire as to cause issues with Resistance by adding to much wire between th battery and esc.
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Old 09-01-2010, 05:23 AM
  #33  
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Default Safety switch, plug, disconnect...

Originally Posted by stuart View Post
henry,i like the picture of that plug. it shows we don't need to add so much extra wire as to cause issues with Resistance by adding to much wire between th battery and esc.
Where to mount a safety switch and harness presents a different challenge on every airplane. With the Midget Mustange 60, mounting it on the hatch cover just worked out. We can reach under the airplane without getting near that 15x8 razor edged prop.
Here are a couple photos of a different airplane. Here the switch is mounted in the side of the fuselage. Once you pull that plug, no way is that motor gonna start. This, by the way, is an old LT-25 converted to electric.
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Old 09-01-2010, 06:09 AM
  #34  
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Originally Posted by Henry111 View Post
Where to mount a safety switch and harness presents a different challenge on every airplane. With the Midget Mustange 60, mounting it on the hatch cover just worked out. .
Got the same setup on one of my 6S2P A123 battery, 60 Amp load setups. Finally, after 7 years, had to put new pins in the connectors.
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Old 09-01-2010, 08:19 PM
  #35  
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Originally Posted by Henry111 View Post
Hey Pete, thank you so much for clearing my head on that very technical and important point. The next time an RC electrical question comes up let's all be sure to check the NEC Code Book.
Exuse me for sharing some information! I guess I should apologize for this post as well http://www.rcgroups.com/forums/showt...ghlight=deoxit I am sorry I interrupted this thread also http://www.wattflyer.com/forums/show...loscope&page=2
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Old 10-14-2010, 01:42 PM
  #36  
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......I have metal barbecue skewers that seem quite sturdy. But I worry that a rod could become a projectile if the motor force snaps it or yanks it out! So I guess this needs some experiments, on an OLD airplane if I ever get that far. (And run the experiment from the other side of a wall.)
It's the starting torque presumably that's the danger. So could I program the ESC for a slow start? (as if it were on a heli) Something else to learn about.......
And accidents in General Aviation are often caused by carelessness, to which I am prone...
Actually a cocktail stick is enough for most ... as the start is easily stalled ... an electric motor does most damage when it's up to speed and it has 'momentum' in the spinning prop + the sharp edge.

My father was Chief Flight Ops Insp. for Civil Aviation Authority, British Govt Dept. - he would always say after an accident investigation :

Most accidents start at the breakfast table before it gets anywhere near an aircraft.

Back to switch - I asked this question on another forum and got very similar answers as above. I am not a great lover of the ESC 'software arming" function ... I've still got caught out. My original brushed ESC had a disabling push button that had to be pushed in for 2 sec's to get power switched on for motor. It didn't carry the motor power - it was connected into the internals of the ESC and only had low power across it .... why cannot similar be made for brushless ?
I thought it strange that a brushed motor with less power than a brushless should have this safety feature but not a Brushless.
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Old 10-14-2010, 01:46 PM
  #37  
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Originally Posted by ArneH View Post
My Transmitter has a throttle cut switch:



The long switch cut the throttle. Smart solution if you need it.
The FS 9TX ... FlySky / Eurgle / iMax etc. - good to see one !

Nigel
Yahoo group - Flysky !
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Old 10-14-2010, 01:59 PM
  #38  
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the plug idea for motor leads is a good idea ...

I get impression from OP that it's ONLY power to the motor he wants to switch, not battery to ESC.

A brushless motor has 3 leads ... so if two are connected to a dean plug or similar and mounted - all you need is the other half of the deans to arm the motor. Simple .... thanks to other post for jogging my brain cell !

As to RX - that's easy to sort as most radio's have a RX to battery switch harness incl. charge connection. Instead of plugging ESC direct into the RX ... plug in via the switch harness, switch mounted as req'd.
Generally then the throttle will not work as it has no RX to communicate with, ESC will not send instruction as it has no RX signal on its' white / yellow lead ....

I'm now thinking on that plug idea on the brushless motor leads .... brill !
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Old 10-14-2010, 03:11 PM
  #39  
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Originally Posted by solentlife View Post
As to RX - that's easy to sort as most radio's have a RX to battery switch harness incl. charge connection. Instead of plugging ESC direct into the RX ... plug in via the switch harness, switch mounted as req'd.
Generally then the throttle will not work as it has no RX to communicate with, ESC will not send instruction as it has no RX signal on its' white / yellow lead ....
Doesn't work because the standard harness has only two wires for battery. You'll completely lose the signal connection to the ESC whether the switch is on or off...not very useful.

Anyway breaking the signal lead so that ESC input is open circuit but the ESC is still powered by the main battery (and probably still armed) is exactly the most dangerous condition, where motors come on accidently. ESCs can and do pick up interference which fool them into believing they've just had a full throttle command. I've seen it happen (and provided the sticking plasters) .

BTW breaking one motor lead doesn't stop it running either. A disconnect plug in the battery to ESC leads is the only safe way.

Steve
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Old 10-14-2010, 03:27 PM
  #40  
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Originally Posted by slipstick View Post
Doesn't work because the standard harness has only two wires for battery. You'll completely lose the signal connection to the ESC whether the switch is on or off...not very useful.

Anyway breaking the signal lead so that ESC input is open circuit but the ESC is still powered by the main battery (and probably still armed) is exactly the most dangerous condition, where motors come on accidently. ESCs can and do pick up interference which fool them into believing they've just had a full throttle command. I've seen it happen (and provided the sticking plasters) .

BTW breaking one motor lead doesn't stop it running either. A disconnect plug in the battery to ESC leads is the only safe way.

Steve
I think you've mis-read my post.

I am not talking about the battery to ESC - that is easy to sort and is not what OP was talking about, He wants to stop motor spinning up when checking other items, but doesn't want to be safe by taking prop of.

My suggestion is to have TWO of the motor leads via a plug / socket such as deans outside the plane so TWO leads of the three to the brushless can be disconnected at will.

As to an ESC firing up on interference ... I've obviously not been in the Electric Model game as long as most - but never heard of it happening. I've heard people talk about a 'friend of a friend who heard about it happening ... ' - which to be honest is a bit like fishy tales - hard to accept.

Most ESC's when signal or leads are disconnected go to failsafe in that they shut down ... you only have to trial this by pulling wires etc. on your own plane and watching / listening ... the beeps themselves will tell you state of the ESC and mine tells me when signal is lost - that it's cut out the motor side. The only way I can then get it back on is to re-power the ESC. Second - the switch harness will disconnect the THREE contacts in the RX plug .. so there's no signal and no power either on that RX lead ... control sircuit is then DEAD ... motor power control NEEDS that control circuit powered up and talking to it.

Sorry I'm still on the side of deans with two of the motor leads to it ... and if necessary a switch harness in line ESC to RX. (So far I have fitted neither - but once I get back frtom my next shipping assignment - will be fitting that deans ... or a 3 pin system if I can find one NOT bullets !!

My Trex 450 of course is easy as the motor bullets sit available outside rear bottom of canopy and my battery Deans pokes out bottom of canopy ...
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Old 10-14-2010, 03:46 PM
  #41  
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Originally Posted by Victory Pete View Post
Exuse me for sharing some information! I guess I should apologize for this post as well http://www.rcgroups.com/forums/showt...ghlight=deoxit I am sorry I interrupted this thread also http://www.wattflyer.com/forums/show...loscope&page=2
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There is nothing wrong with sharing information, and no need to apologise.
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Old 10-14-2010, 03:50 PM
  #42  
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Originally Posted by Victory Pete View Post
I am an electrician and we call some switches "Disconnects" The term is used mostly in the NEC codebook. A switch is mostly used to control a "Luminaire" (Codebooks term for light fixture).
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Disconnect is what my cell phone does in a fringe area. Switch is what my gradeschool teacher used on me.

Impossible to make anything mechanical/electrical idiot proof. Just winds up more complicated.
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Old 10-14-2010, 06:20 PM
  #43  
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Originally Posted by solentlife View Post
I thought it strange that a brushed motor with less power than a brushless should have this safety feature but not a Brushless.
At least for my Castle Creations Phoenix ESCs, on power up, they will not arm, unless the transmitter is at low throttle. And, if you turn on everything at perhaps 10% throttle, that transmitter stick position is now your motor off position.

So, if you turn on everything at 10% throttle, nothing happens until you move the throttle up from that 10% position.

But, safety is first. I make it a rule to be behing the wing of the airplane before plugging in the battery to the ESC and motor. Don't ever want to try to stop a 14X10 APC-E prop with a one Kilowatt Hacker A50 motor with any body part.

It's best to treat any motor that has battery power to be armed, and ready to go. Just like having a loaded weapon.

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Old 10-14-2010, 06:58 PM
  #44  
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Originally Posted by mesh View Post

Another thing to ponder is that most motors are pretty weak when starting, so if you inserted a dowel or barbecue skewer alongside the motor into a conveniently placed hole, you would lock the prop down pretty effectively. Try holding the prop while starting the motor, not much force there. (I've only done this up to a 40A motor running 11x6 though
Whoa!! I disagree! In fact, electric motors actually are STRONGEST at start up! They have incredible torque at low speeds.
This is EXACTLY the reason why locomotives are electric (you thought they were diesel, right?)Actually the diesel just powers a very strong GENERATOR for the electric motor that turn the wheels. True story!

Be cautious....Use some kind of a switch or jury rig a rubber band.

What a 40A motor with a 11x6 prop could do to a forearm or finger is NOT PRETTY!!!!!
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Old 10-14-2010, 11:21 PM
  #45  
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Originally Posted by pattern14 View Post
There is nothing wrong with sharing information, and no need to apologise.
I was being sarcastic!
Thanks
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Old 10-14-2010, 11:40 PM
  #46  
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There was never probably & never will be, a INDUSTRY standardised start up procedure. It is so dam simple to do with electronic chips in use.

There is nothing but GREED & LAZINESS stopping it.
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Old 10-15-2010, 10:56 AM
  #47  
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Originally Posted by solentlife View Post
As to an ESC firing up on interference ... I've obviously not been in the Electric Model game as long as most - but never heard of it happening. I've heard people talk about a 'friend of a friend who heard about it happening ... ' - which to be honest is a bit like fishy tales - hard to accept.
As I specifically said that I've seen it happen more than once I assume you're calling me a liar for some reason of your own (ignorance mainly I guess).

BTW your theory that an ESC needs power on the RX lead before it works is obvious rubbish...many people have for years disconnected that power lead to the ESC and run Rx and servos from a separate BEC or battery. An ESC needs only signal and ground connected, it gets all the power it needs internally from the motor battery.

End of conversation and time to check if this forum has an ignore list.

Steve
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Old 10-15-2010, 02:42 PM
  #48  
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ANY HOUSE OR BUILDING WITH LARGE AMOUNTS OF METAL IN IT OR ON IT, CAN CAUSE INSTANT START UPS AT FULL POWER !!!!!!!!!!!!!!!!!!!!!

I designed electrical & have a very good backround in electrical interference & random triggering of SAFE equipment.

I have a basement with LOTS of airconditioning steel ductwork in it. VERY DANGEROUS !!

More than 5 times I have screwed up testing stuff & FORGOT to turn the transmitter on FIRST. CRAP !!!!!!!!
I had a motor fly out of my hand, bounce off the wall then the smooth side of the furnace duct, right back at my crotch. 2" more, no balls. Reason ?? The metal surfaces very nicely REFLECT the radio frequencies of the tiny receiver back. Also. ANY arcing on the electrical power lines in the house can cause triggering of the RECEIVER & ESC. Vacum cleaner, flourscent lights, drills connecting a battery charger, car starting in the garage & many others.
Just the light rubbing together of 2 pieces of metal can cause reveivers to send full power signals to the ESC.

THINK or pay the price in our hobby.
Imagine what could have happened to a child standing next to me . In the face would definately have happened.

I now wear a full face shield, a full length winter coat & work gloves.
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Old 10-15-2010, 06:17 PM
  #49  
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Originally Posted by slipstick View Post
BTW your theory that an ESC needs power on the RX lead before it works is obvious rubbish...many people have for years disconnected that power lead to the ESC and run Rx and servos from a separate BEC or battery. An ESC needs only signal and ground connected, it gets all the power it needs internally from the motor battery.
Things are sure changing on this subject. Just picked up a Castle Creations 80 Ampere HV ESC. It's instructions indicate "Do NOT disconnect the servo red wire" Without the red wire, it won't work.

The instructions also indicate that the system is to be powered up with the transmitter at 1/2 throttle, and to not move the transmitter to idle until you are ready to arm the motor. (These CC ESC's will not arm unless the throttle is at minimum)

Guess you've got to read the manual on any of these products!
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Old 10-15-2010, 06:32 PM
  #50  
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Originally Posted by kyleservicetech View Post
Things are sure changing on this subject. Just picked up a Castle Creations 80 Ampere HV ESC. It's instructions indicate "Do NOT disconnect the servo red wire" Without the red wire, it won't work.
That's always been true for any OPTO ESCs like the CC HV range.

It's never, in my experience at least, been true for any ESC with BEC like those I was talking about.

Nothing has changed it's just that that things are rarely quite as simple as a concise statement may make them seem. OTOH if everyone detailed every possible exception and example every time they wrote anything we'd never get to the point .

Steve
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