Safety Protocol For Electric Startup And Shutdown

[Richard Entwhistle 823412]

I know next to nothing about all the combinations of batteries, controllers, timers and motors but I do known when something looks unsafe to me.  An electric powered  plane has been flown at our local field that has no way of stopping the motor run once the "start switch" has been activated.  The motor only stops when the timer has done it"s program.  Several times at the start of the flight there is a "beep" and the prop turns for a second and then nothing and nothing.  Flier and holder look at each other for what feels like forever.  The flier puts the handle down and walks toward the plane, the holder lets go of the plane and steps back.  After a little checking and electrical work by the flier there is a repeat of the starting procedure and most of the time the motor does come to life.  On several runs the timer has failed to stop the motor and after fifteen minutes or more the batteries are drained and the flight ends.  The question: Should there be a main fuse or switch on the outside of the plane that disconnects the motor from the battery?   The  picture on page 85 of the Sept. Model Aviation is what proms this post.

Thanks
Richard

[Tim Wescott]

First:

Wow.  That's weird.  I wish that I had been at the meeting yesterday (I was doing taxes, and getting #1 son moved into a PSU dorm, and you know how regularly I make it anyway).  I might have been able to offer more deep insight.

Second:

There's been mucho discussion about the inadvisability of disconnecting main power while the motor is running -- it can cause ESCs to die early deaths, among other things.  OTOH, in my opinion, if it's a choice between frying an ESC and torching an entire plane -- yank the plug!  Doing so when the motor isn't spinning is as safe as houses.

Third:

An external arming switch, or a battery disconnect that can be accessed when the prop is spinning, is a good thing.  I'm comfortable with this being done after taking off a hatch, particularly if the hatch can be taken off while the prop is spinning.

Fourth:

If you review Brett Buck's proposed rule for electrics, it basically states that you make sure that someone's holding on to the plane any time the battery is connected to the ESC.  In the case you mention, the sequence on a timer failing to start should have been that the flier puts down the handle and walks toward the airplane.  Then the helper hangs on until (a) he is directed to let go by the pilot, and (b) he has verified that the pilot has a good grip on the plane.  Under no circumstances should both folks be standing there looking at an un-restrained plane, scratching their heads and waiting for it to take off.

Fifth:

There's something odd going on with the setup.  While disconnecting the main battery lead is pretty harsh, unplugging the timer from the ESC should be safe as houses, and unless the ESC is really, severely malfunctioning, should result in no damage and a motor that's not spinning.  I think if I were having those problems I'd leave my ESC to timer wires dangling outside the plane, either by poking them out of the hatch, or leaving the hatch off.

[Randy Powell]

All the guys here use a plug that is pulled to disconnect the battery from the motor. That is routine. Plane lands and plug is pulled or if any problem comes up, the plug is pulled. i don't know about a failed timer in the air. Haven't seen it, but I would imagine it's sort of like with an engine goes way lean and you get 15 minutes of spinning in circles.

[Mike Haverly]

  Simple answer to the original question is YES!

  As far as I know there is no rule in effect, (yet), but common sense tells me that you should be able to shut things down safely after starting.  My first electric model last year gave me fits at Northwest Regionals and I never did find the root of the problem.  Similar symptoms, push the button and various results.  I'm pretty sure the problem was solder joints or at least a bad connection somewhere.  After replacing nearly everything the problem went away but the safety plug stayed!

  Profile models are a little easier but I think there should still be a disconnect besides the battery.

  Mostly all my opinion.

[John Cralley]

I know next to nothing about all the combinations of batteries, controllers, timers and motors but I do known when something looks unsafe to me.  An electric powered  plane has been flown at our local field that has no way of stopping the motor run once the "start switch" has been activated.  The motor only stops when the timer has done it"s program.  Several times at the start of the flight there is a "beep" and the prop turns for a second and then nothing and nothing.  Flier and holder look at each other for what feels like forever.  The flier puts the handle down and walks toward the plane, the holder lets go of the plane and steps back.  After a little checking and electrical work by the flier there is a repeat of the starting procedure and most of the time the motor does come to life.  On several runs the timer has failed to stop the motor and after fifteen minutes or more the batteries are drained and the flight ends.  The question: Should there be a main fuse or switch on the outside of the plane that disconnects the motor from the battery?   The  picture on page 85 of the Sept. Model Aviation is what proms this post.

Thanks
Richard

The simple answer is yes there must always be a way to disconnect the battery from the system (the ESC in this case). For a full bodied model where the battery is enclosed in the fuselage an external "disarming plug" is essential unless the wires from the battery to the ESC are exposed with the connecting plug  outside the fuselage and accessible! In the case of profile models the battery connecting plug will normally be easily accessible for disconnecting the battery.

It would be of interest if you would tell us what brand of timer is being used. Timers that I am familiar with will stop sending out the signal (equivalent to the transmitter throttle signal) when the "start" switch is pressed a second time during the timing cycle. I know of no timers that will continue to send out a signal after the time interval is completed and if this one has run for 15 minutes until the battery is exhausted, then it should be returned to the manufacturer for evaluation. In no case should it be used again!!

It would be helpful if you can provide us with the technical information about what components are being used in this model. Normally an ESC would have shut down the motor LONG before 15 minutes because the battery voltage would drop below a preset safety level. To run for 15 minutes, it would seem that the battery being used has WAY too much capacity.

My 2 cents.

[Richard Entwhistle 823412]

Many combinations of components were used so I can not give any information as to what brands were installed.  I stand corrected by a fellow flier that the timer did not fail for the extended motor runs but that the timer was removed from the circuit because of problems with it and the desire to fly was greater than the possible damage to the batteries.
Later
Richard

[Tim Wescott]

That's even weirder yet -- if the pilot is who I think it is, he's running a brushless motor -- you can't get those to turn without an ESC, and you can't get the ESC to go without feeding it a pulse train that looks like it came from a receiver.  So you'd need something in there instead of a timer.  I suppose that if there were room you could cram a servo tester in there, but that would be, well, weird.

For that matter, in this day and age running a brushed motor would be weird, too.

[pmackenzie]

For testing a cheap receiver and transmitter can replace the timer. How cheap?  less than $30
http://www.hobbyking.com/hobbyking/store/__9042__Hobby_King_2_4Ghz_6Ch_Tx_Rx_V2_Mode_2_.html

 Also has the advantage that you can adjust motor speed during flight.

Pat MacKenzie

[Douglas Ames]

Maybe the timer manfrs. need to add an external disable "kill" switch for the timer (that's in addition to an arming switch for the power leads).
 

[pmackenzie]

Maybe the timer manfrs. need to add an external disable "kill" switch for the timer (that's in addition to an arming switch for the power leads).
 

There is at least one timer that has a separate arming switch and motor start switch.
In order for the motor to start you have to cycle the arming switch from off to on, and then use a magnet to engage the motor start hall effect switch.

Everything has to be done in the correct order, and because all inputs have to cycle they can't fail and cause a false motor start.

Turning off the arming switch will remove the signal from the ESC, and it will stop the motor.
 It will also reset the timer so that the complete arming and start sequence will have to be repeated.

The motor arm and start sequence prevents accidental starting.

[Mark Scarborough]

all the timers I have seen also will stop after the start switch is depressed again,, and I know of no way to run a brushless without a timer,, the ESC HAS to have a signal..

sounds to me that the person with this system needs to learn more about his system before he puts it on the circle,, its easy to test run equipment on the ground inthe pits,, just take the prop off,, and run it that way, very low stress on components,,

[John Cralley]

Mark,

I agree that as far as I know all commercial timers will stop with a second push of the start button (switch). However it is perfectly possible to run a brushless motor using a servo tester in place of a timer. I do it for bench testing motors but to fly a control line model using a servo tester instead of a timer is a terribly stupid idea!!! 

[Mike Haverly]

     Mark is right, the start button is also the stop button, at least on the set up I'm using.  Pretty basic.  That still doesn't make the arming switch unnecessary.  If you arm the system before going to the circle just a bump of the button could start the operation.  The arming switch eliminates at least that.
 
     One problem with using the "plug and play" systems on the market is you could miss out on the basic use of the  systems.  We all had to learn to use glow engines.  They are not as easy as it seems when you throw in all the variables. Remember the RTF Cox series?  They were difficult at best to operate for a rank novice.  Sometimes they ran, most times they did not.  Very discouraging.  There is a lot more to be learned by getting the components and building an airplane.  Electrics are no different.  Lots of stuff out there, but a lot of information also.  I was lucky in that I had some World Class help available and wasn't afraid to ask for it.  Bypassing components for the sake of a couple of flights without finding the problem is just plain stupid.  I'm pretty sure I know who this is also and he should have sought help.

Again mostly my opinion and not much sympathy.

[Brett Buck]

     Mark is right, the start button is also the stop button, at least on the set up I'm using.  Pretty basic.  That still doesn't make the arming switch unnecessary.  If you arm the system before going to the circle just a bump of the button could start the operation.  The arming switch eliminates at least that.

  BTW, I am not sure what might happen if you pull the plug out when it is at full power. You might get one heck of a voltage spike and wipe out the controller or timer. Still better than having a runaway.

    Brett

[Wynn Robins]

seems like the person involved has no idea what they are doing with the system. 

as mentioned above - it should be tested BEFORE it gets to the circle to ensure that it is operating as it should

I use arming plugs on all my electrics - stupid not to!

[Leo Mehl]

Richard does not know what he is talking about because that setupm had a switch and can be stoped at any time.

[jjorgensen]

Exactly how is it it more dangerous for an electric model to not have a "separate'' shut off than an IC model? I have seen IC models have runaways after start when a prop nut comes loose, with motor going to max rpm, and seeing the holder stuff the engine into the ground to stop it. With an electric, if the prop nut comes loose, the motor stays at the same rpm, so it is actually safer. Do we need to have fuel shutoffs on all of our IC models, like they have in combat? The only way I know of to stop a runaway IC motor is to pinch off the fuel line, which places the fingers awfully close to the prop. It seems the only people who find this necessary are those who, admittedly, know little about electrics. If something is not going according to plan, the holder just holds on to the airplane until the battery is disconnected. The holder is the failsafe mechanism.

[Leo Mehl]

I feel the same way for a lot of the guys on our flying circle use APC props for their IC modeles and They are just as dangerous as electric or more so. I feel that if anyone has a problem with what is being done should talk to the person and ask questions before posting a thread about it on stunt hanger. It makes the person look bad to his pears and Is very disturbing to me!

[RandySmith]

There was nothing wrong with the questions asked on this thread, this is what the forum is for.

Randy

[Tim Wescott]

The part that bothers me, if what Richard was seeing is as he stated it, isn't the shutoff -- that's just a matter of convenience, and maybe saves the pilot from a torched model (and, IC models will catch fire from time to time, too, even if I haven't seen it).

What concerns me is his description of the action where there's a system that appears to be turning on unpredictably, yet which the pilot (I'm still not naming names, since I wasn't there) and his helper aren't making sure to have a hand on at all times that the battery is connected.  I don't think that a flyaway from the ground at that circle is very likely to make it as far as I-5, but it could sure scare the snot out of the baseball moms across the driveway and possibly do damage to cars, people, or (perish the thought) nearby innocent models.

If the model was, indeed, under physical control any time the battery was connected then I'm happy: the whole external cutoff thing is, to my mind, a side issue since at worst you'll just need to hang onto the tail of your model while the front end burns, or snub it off in the dirt like a really big stogie, neither of which is going to give a baseball-throwing attorney an opportunity to quiet down his Saturdays by getting the city to shut down the field.

[Steve Helmick]

The easiest and quickest way to shut off an IC engine is to put a finger over the pipe exit or tube muffler exit. A tongue muffler is not so easy, and will burn the crap out of you. Having a rubber ducky on the pipe or tube muffler helps a lot. You will get a slight burn, but it won't bother you much, or more than a few days. With a hard tank, turning it nose down is the standard method, but it is slower. If you don't know if the model has a hard tank or a clunk tank, the finger over the end of the rubber ducky is good and faster than any other method except maybe a rag into the prop. If the prop has left the engine, that's not going to work, tho.

The electric systems I've seen put out a pretty good spark when the arming plug is installed, which doesn't look like a good thing to me. But I don't know chit about the electron burners, and really am just not interested in them. I do launch them for several guys here in the area. Nobody's ever told me what to do to shut one down, but I'd start by pushing the button, and if that didn't do the job, I'd pull the arming plug. The arming plug seems to be standard equipment here, as it should be. It'd be tempting to jam the spinner into the asphalt, tho.  Steve

[Tim Wescott]

On all the clunk tanks that I ever owned, the only way to get the clunk to fall to the front of the tank was to have the entire airplane collide violently with the ground (which, because I'm not always on top of the invisible details, means a second crash to follow).

The spark on connection of the battery is charging up the ESC capacitors; it's not good, but it's mostly shortening the life of the arming plug and those caps.

Electric motors are inductors; when you open the switch on an inductor you get a real spark, or at least a honkin' big voltage spike.  In theory those caps on the ESC could absorb that spike, but given that ESC manufacturers tell you to limit the wire length to the battery, I don't think there's enough capacitance there to do the job fully -- meaning that the spike will rip through your ESC circuitry, doing damage ranging anywhere from nothing, through "dead but doesn't know it yet" all the way to a torch the next time you plug it in.

[Igor Burger]

And why do not you simply use slide switch???

[Tim Wescott]

And why do not you simply use slide switch???

That powers down the timer, but doesn't remove main battery power.  The arming switches being talked about are in the main battery leads.

Your slide switch would -- in the absence of some really bizarre ESC problems -- cut the motor right off, without (unless it's a poorly designed ESC) damage.

[Brett Buck]

Electric motors are inductors; when you open the switch on an inductor you get a real spark, or at least a honkin' big voltage spike.  In theory those caps on the ESC could absorb that spike, but given that ESC manufacturers tell you to limit the wire length to the battery, I don't think there's enough capacitance there to do the job fully -- meaning that the spike will rip through your ESC circuitry, doing damage ranging anywhere from nothing, through "dead but doesn't know it yet" all the way to a torch the next time you plug it in.

   Which was was I was referring to above.

   Brett

[RandySmith]

"The easiest and quickest way to shut off an IC engine is to put a finger over the pipe exit or tube muffler exit. A tongue muffler is not so easy, and will burn the crap out of you. Having a rubber ducky on the pipe or tube muffler helps a lot. "


Or you can just pinch the rubber deflector or bend it, either works right away. with a tongue, you can use a small rag or a  glo plug paper package over the holes, you will not get burned that way,
I have seen a couple of RC I/C planes burn.....

Randy

[Howard Rush]

I

with a tongue, you can use a small rag of glo plug paper over the holes, you will not get burned that way,...
Randy

I'm not sticking my tongue on a hot engine, with or without the small rag of glo plug paper.

[RandySmith]

I
I'm not sticking my tongue on a hot engine, with or without the small rag of glo plug paper.

Howard  if.. you stick your tongue on your hot engine, all that will happen is you will get a mouth full of electrons.... used bad tasting ones at that !!   

Randy

[Richard Entwhistle 823412]

The question was: "Should there be a main fuse or switch on the outside of the plane that disconnects the motor from the battery?", not that APC props are maybe unsafe.  The overwhelming consensus is YES there should be a disconnect.  With a disconnect like an ArmSafe, WWW.SharpRC.com, Page 35 Sept Model Aviation, installed one could safely do work on any part of the plane with the battery installed without the worry of getting ones fingers, hand etc chewed off.  It's also a lot safer for fellow fliers and onlookers.

 Later
Richard

[Brett Buck]

The question was: "Should there be a main fuse or switch on the outside of the plane that disconnects the motor from the battery?", not that APC props are maybe unsafe.  The overwhelming consensus is YES there should be a disconnect.  With a disconnect like an ArmSafe, WWW.SharpRC.com, Page 35 Sept Model Aviation, installed one could safely do work on any part of the plane with the battery installed without the worry of getting ones fingers, hand etc chewed off

  Virtually everyone who is running electric has been using an arming plug that does exactly this for many years now.

     Brett

[Tim Wescott]

The question was: "Should there be a main fuse or switch on the outside of the plane that disconnects the motor from the battery?"

I think it's more important that the BBEP (Brett Buck Electric Protocol) be followed and the plane be under positive control any time the battery is connected to the ESC.  The external disconnect is important, but not nearly as much.

One thing that hasn't been mentioned in this thread, but maybe should for the slimers who are contributing, is any time the ESC is live the prop arc should be treated as if the motor is running -- that way, if something makes the motor come on suddenly, no one gets bitten.  Do that, observe the BBEP, and even without the external disconnect no loose airplanes or body parts will go flying outside of the circle.

[Trostle]

I think it's more important that the BBEP (Brett Buck Electric Protocol) be followed and the plane be under positive control any time the battery is connected to the ESC. 

(Clip)

By the way, that BBEP rule change proposal by Brett just passed the Final Vote of the Aerobatics Contest Board.  The AMA has not yet made it official but it should be posted soon on the AMA website that it did pass.

Keith

[Brett Buck]

By the way, that BBEP rule change proposal by Brett just passed the Final Vote of the Aerobatics Contest Board.

   Before everyone starting giving me the blame/credit - all this rule does is make a requirement out it what almost everyone was doing anyway. It was hardly my original concept - I saw people with arming plugs about 10 years ago, basically from the very beginning. Since it was obvious.

  Call it the CSEP - Common Sense Electric Protocol.
 
    Given that it is in the rule book, it applies only to competition. For practice or sport flying I strongly urge following the same principle.

   For solo practice, I would suggest caution for those flying electric by yourself with a stooge. The biggest point of vulnerability is at the end of the flight, after the motor stops and the airplane lands. At some point you are going to have to remove the thong, drop the handle, and go to the airplane. If it starts at that point, there is plenty of power left to let the airplane fly loose, If it does, don't try to grab the bare lines to stop it!  The likely result is a severely sliced up finger/hands as the cable slips by and act like a saw. That, I *have* seen in person and there have been numerous other examples. Then you have severe cuts, and no one around to help. Unless you are right at the handle, or right at the airplane to grab something solid, I think it's probably best to just let it go and take you chances that (very likely) it will crash quickly rather than to try to grab the lines.

   I don't think that the potential for disaster is much higher for stooge flying with electric than it is for IC. The unintended restart scenario above is only one of many ways for a stooge flight to go wrong.   I think either is risky based on my own experience and that of others. I know people will do it anyway so I am not going to waste my time trying to talk anyone out of it.

    BUT, even though you have a delayed start, YOU SHOULD STILL USE A STOOGE WITH POSITIVE RETENTION! Otherwise you set the timer and hope nothing happens before it starts, like, the wind blows it sideways, the airplane rolls strangely as the motor slowly spools up, etc. I don't care if Igor did do it at a previous WC, it's still a bad idea. It's not a rule so it's up to you.

    Brett

[Igor Burger]

hmmm ... I hope I am not source of everything wrong on this world 

[Brett Buck]

hmmm ... I hope I am not source of everything wrong on this world 

   No. Although I did explore that possibility for quite some time.

     Except for this, you are darn near perfect!

   Brett

[Steve Helmick]

I'm sure that if the wind is blustery, Igor and all would have a launcher wait for the smoke to build pressure and rpm to rise before waving for a release.

I was wondering, does everybody that flies CCW and uses "pusher" props launch with the model yawed out about 5 degrees to get a smoother looking start to the takeoff roll?  Steve

[Igor Burger]

so far I did almost 3000 electric flights (I count them, because of battery life statistic) and I can say that eliminating the human factor at the start and stressy release from hand (I have set 2 seconds spool up) gives me no troubles and singnifficantly safer starts, while broken prop on grass was and we have seen on last WCh is, easy to see. So we can theoretize about potential danger of slow start, reality for me is different. It works for me and I will simply do it that way. But I am not propagator or advocate of slow start, it simply works for me, if someone feels it different, then I will not try to convince him do it different. ... simple