Author Topic: Arming device pictures (Read 3253 times)

Jason Greer · « **on:** October 31, 2011, 08:15:40 AM »

With all of the talk about arming devices lately, it would be nice to see how others are implementing reliable arming systems. Hopefully this post will not turn into an arming device argument or debate. I'm just looking for ideas.

Thanks,
Jason

Dean Pappas · « **Reply #1 on:** October 31, 2011, 08:22:05 AM »

Sounds good! No debate ... just how to.

I'm betting there are some classy looking setups out there that would ADD to a plane's impression at Appearance Judging.
Let me offer an opening gambit: no fancy arming switch other than the standard power plug ... but easily accessible under a top-loader hatch that comes off one-handed and without tools.
Some use magnets, though I have to say I'm not crazy about that, and others use neat spring latches that can be quite bulletproof.

Regards,
Dean P.

Jason Greer · « **Reply #2 on:** October 31, 2011, 08:40:48 AM »

Thanks Dean. You nailed it on the head. We just need to see reliable devices that are not to difficult to implement.

Douglas Ames · « **Reply #3 on:** October 31, 2011, 08:55:30 AM »

This was posted by John Rist on the other thread.
Can't think of an easier way to disarm a battery short of a knife switch. A little lanyard might help to keep it nearby (i.e.- not lost in the grass).

http://www.sharprc.com/

Igor Burger · « **Reply #4 on:** October 31, 2011, 09:13:08 AM »

That solution looks good, but ignores facts. Longer leads can damage FET transistors and such construction does not allow charging anti spark resistors which are necessary for higher volatage. Construction of safe arming plug is not trivial task.

Tim Wescott · « **Reply #5 on:** October 31, 2011, 09:48:09 AM »

I don't think a snubber is going to be necessary if you don't increase your ESC lead length too much (i.e., by more than a couple of inches), and if you don't pull the plug with the motor running.

My experience with batteries has been that the stock lead length is generally a mild inconvenience in hooking up; I always leave the wire routing on my RC electric planes until last, and I always regret it. If I were to plan out the wiring from day 1 I suspect I could make a neater setup with shorter wires.

Igor Burger · « **Reply #6 on:** October 31, 2011, 09:57:23 AM »

Tim, this thread is recomandation fro those who do not know how-to, recommending such thing which could cause your model burn without at least a note is not good ... especially if the mistake in design or installation is not visible immediatelly, just the ESC will burn after 100 flights

I affraid whole this debate leads to higher dander as before, if this should be safety device, it must be done well, otherwise it just bings much higher risk on place which simply not everyone see right now.

Tim Wescott · « **Reply #7 on:** October 31, 2011, 10:28:38 AM »

Igor: point taken. I don't know that I agree with you about the relative dangers, but I see your point, and we're hijacking Jason's thread anyway.

Jason: This question has been asked before, there are several threads dealing with arming plug pictures. If you use the search feature from the forum heading then you should find at least some of them.

Jason Greer · « **Reply #8 on:** October 31, 2011, 11:36:53 AM »

Tim, no problem. I have searched the older threads, but I thought there might be some newer ideas as far as the safety and implementation issues that Igor has pointed out. In the past I've always just connected my battery on the circle and disconnected it before leaving the circle. Since I always have a dedicated helper that knows exactly what to expect, this system works for me and I do not use an arming plug. The battery is never connected on my model unless I am on the circle and it is always restrained by my helper. If I do install an arming device, I want something reliable that is not going to potentially harm my ESC. I understand that the ESC can be damaged over time by lengthening the input power leads.

Tim Wescott · « **Reply #9 on:** October 31, 2011, 12:01:42 PM »

I think that if you go with the ESC manufacturer's advice about total wire length (IIRC the Castle ESC's have little drawings with measurements) you'll be fine. If you use a full-length ESC harness, plus a full-length battery harness, then add some gargantuan harness for the arming plug on top of that -- then you'll be in trouble.

Jason Greer · « **Reply #10 on:** October 31, 2011, 12:21:34 PM »

10-4, thanks Tim.

Tim Wescott · « **Reply #11 on:** October 31, 2011, 12:48:34 PM »

Quote from: Dean Pappas on October 31, 2011, 08:22:05 AM

I'm betting there are some classy looking setups out there that would ADD to a plane's impression at Appearance Judging.
Let me offer an opening gambit: no fancy arming switch other than the standard power plug ... but easily accessible under a top-loader hatch that comes off one-handed and without tools.

That would certainly be a good choice, IMHO. You need a battery hatch anyway, and you need to make it look good, so you may as well make that part of arming.

Quote

Some use magnets, though I have to say I'm not crazy about that, and others use neat spring latches that can be quite bulletproof.

I'm really ambivalent about the whole "hold things on with magnets" idea. On the one hand I have yet to see a part that's held onto a plane with magnets fall off (except for one that I built -- and I know what I did wrong). On the other hand -- magnets?

bob branch · « **Reply #12 on:** December 20, 2011, 06:39:10 PM »

I love my magnets! But if you are going to use them they need to be large enough to really hold and lateral loads both side to side and fore and aft need to be handled by something else. Actually a tongue or dowel at the front end of a hatch and a good size magnet at the back with a few lateral guides really is a secure hatch. Overkill might be the one I installed on my t-rex (see build thread this forum.).. you can pick the plane up by the hatch!.... but on the other hand, it ain't coming off.

bob branch

bob branch · « **Reply #13 on:** December 27, 2011, 08:42:18 AM »

I'd like to pose another question. I have seen in the threads on arming things several comments like Dean's earlier about hiding the device behind a removable hatch so it is not seen. Doesn't this defeat the purpose to some extent? One of the issues posed in one of the "do it or not" threads was that the assistant should be able to disable the plane before it is removed from the circle. A number of comments were made on this regarding people at contests often just being quickly recruited to carry the plane in or out to the circle and essentially not being familiar with the plane. It seems to me that if the device is out of sight or anything other than intuitive to understand its use, that it renders the device non-usable until someone intimately familiar with the plane and its operation gets to the model. I have seen a model ground loop on takeoff and fortunately the motor incurred a brief prop strike and did not go to full rpm but was at very low rpm as it taxied around. Fortunately also, I knew the operation of the plane very well having launched it a number of times. This was a time where an arming device would have been helpful but only if it was very intuitive to use. I used the start stop button on the timer that was red and came thru the fuse. On that model it was intuitive as to what might help.... certainly not foolproof as far as how to use, but helpful.

I'd like to encourage thoughts on this as well.

bob branch

Igor Burger · « **Reply #14 on:** December 27, 2011, 09:36:31 AM »

The problme is, that people tend to replace term "arming device" with "switch" ... if you want switch off the power, you should use switch, not arming device

Arming device is good in case that battery connectors are difficult to access, so the battery can be installed without powering of ESC. Arming plug allows to connect and disconect power to ESC easier. Arming device should not be disconnected during run, ESC must be checked after such disconnection, because it can damage it. For switching on and off we have switches of many types which can be installed in model on any place and their look and function can be adopted very well.

I think there is only one way to do it safe in circle, hepler should keep the model until owner/pilot/operator comes and does what is necessary to do. Other people should not operate devices of others, only if they are certain or if pilot asks so. Only pilot is responsive fo his model, not others.

Tim Wescott · « **Reply #15 on:** December 27, 2011, 11:03:15 AM »

Well, an arming device is a switch. It's just a switch that perhaps shouldn't be touched when there's a lot of current flowing through it.

John Hammonds · « **Reply #16 on:** December 28, 2011, 04:05:49 PM »

Quote from: Tim Wescott on December 27, 2011, 11:03:15 AM

Well, an arming device is a switch. It's just a switch that perhaps shouldn't be touched when there's a lot of current flowing through it.

I guess it all comes down to terminology and this is something where we really need to define our understanding. If/when the proposed rule gets passed I'm assuming it will say "Arming Device or Switch" as that's what Brett stated in his original post but if that somehow gets translated to just "Arming Device" in the final version that means something different to me.

I have always considered a switch to be something which could be "Switched" off or on and all components were in situ at all times whereas an arming device was something where part of the circuit was physically removed when "unarmed".

Perhaps I'm just being pedantic and currently this doesn't affect me being in the UK (I obviously still follow common sense rules and always disarm my model before leaving the circle) but if the rule is implemented over there then I'm sure the FAI will embrace it as well.

Not trying to be a smart A$$, just don't want anyone DQ'd on a technicality.

TTFN
John.

eric david conley · « **Reply #17 on:** January 14, 2012, 10:20:33 AM »

I've added a little over 12" of #12 wire between my esc and the battery while installing a arming plug that is easy to get to in case of trouble. In reading Igor's comments adding this wire to the cirrcut may be the reason that I have had 3 fires in the ESCs in my planes in the last 6 months. I thought that they were caused by very minor prop strikes while landing (carrier competition) in which I thought the ESC would have shut down to save the motor and battery. My motors and batteries have never been damaged in these incidents but the ESCs are totalled, burned all the way through, and after I pull the easy to get to arming plug I can just blow the small flame out (sticking ones head in the lions mouth) and the planes receive no damage. I could move the arming plug closer to the ESC but then it would be much more difficult to get to and pull? Is this the choice I'm left with, having it accessible or not, and saving the ESC?

Crist Rigotti · « **Reply #18 on:** January 14, 2012, 11:26:30 AM »

Quote from: eric david conley on January 14, 2012, 10:20:33 AM

I've added a little over 12" of #12 wire between my esc and the battery while installing a arming plug that is easy to get to in case of trouble. In reading Igor's comments adding this wire to the cirrcut may be the reason that I have had 3 fires in the ESCs in my planes in the last 6 months. I thought that they were caused by very minor prop strikes while landing (carrier competition) in which I thought the ESC would have shut down to save the motor and battery. My motors and batteries have never been damaged in these incidents but the ESCs are totalled, burned all the way through, and after I pull the easy to get to arming plug I can just blow the small flame out (sticking ones head in the lions mouth) and the planes receive no damage. I could move the arming plug closer to the ESC but then it would be much more difficult to get to and pull? Is this the choice I'm left with, having it accessible or not, and saving the ESC?

What brand ESC's are you using? Castle ESC's can be programmed for a very sensitive current overload that should prevent them burning out. I doubt that the added wire is causing your problem. You can always add a capacitor to the battery input of the ESC as shown on the Schulze website.

eric david conley · « **Reply #19 on:** January 14, 2012, 12:09:00 PM »

I'm using a Cobra 150A ESC, Scorpion 3226-1400kv motor and a 4s 5000mah 30c TP battery. I would be using a Castle ESC but they are not available right now. I don't know about adding a capacitor to the circuit, are there any instructions around for doing that? Thank you, Eric

Crist Rigotti · « **Reply #20 on:** January 14, 2012, 01:29:01 PM »

Quote from: eric david conley on January 14, 2012, 12:09:00 PM

I'm using a Cobra 150A ESC, Scorpion 3226-1400kv motor and a 4s 5000mah 30c TP battery. I would be using a Castle ESC but they are not available right now. I don't know about adding a capacitor to the circuit, are there any instructions around for doing that? Thank you, Eric

Go here and look up the instructions for 18.61kF2B Controller. How to add a capacitor is in the instructions.

http://www.schulze-elektronik-gmbh.de/index_uk.htm

Igor Burger · « **Reply #21 on:** January 15, 2012, 03:16:14 AM »

Long cables to ESC could be reason for fire, but I do not see any relation between long cable and fire in the case of crash (loaded or stopped motor).

The battery is a peak filtering component in the ESC circuit. Its task is not to allow the motor inductance make high voltage peak when FET transistors switch off the feeding of motor coil. Disconnected coil makes back current which should go back to battery and the battery must "accept" that current. If the battery is not present, or if that battery is separated by long wire with some self inductance, than FETs must survive high voltage peak, and it can damage them .... the result is fire. The same happens when you disconnect arming plug during motor run.

So the solution for arming plug is:

1/ do not disconnect arming plug during run. (well … sometimes it less harmful to save life than risk ESC :- ))) )

2/ if your leads are visibly longer than usual (typically 10”) add LOW ESR capacitors somewhere in the middle of the cable. Good advice is to use the same capacitors as you see on ESC. (the same type, the same voltage and the same size)

3/ you will probably see that connecting battery makes larger spark then before (because of twice higher capacity). Solution is anti spark resistors. Unfortunately some ESC makers does not allow anti spark resistors because they do not add ESC switches (like CC) and slow voltage rising can “confuse” processor, so it is better either to use ESC with switch, or to install switch to the timer, so the timer does not sent arming signal during connecting battery. Use that switch also in case that you want stop motor … it is there for that purpose.

bob branch · « **Reply #22 on:** January 15, 2012, 06:57:24 AM »

Igor

What you have said would seem to negate the need for an arming device if the battery is not connected to the system. If cowls or battery access is created in such a way that that is easily doable (ie without tools) then the model does not have to be connected until the plane is in the circle for a flight and can be disconnected before removing it from the circle. Doesn't it seem like this negates the reason for the rule change proposal that has been discussed here? This is the way many of the planes in my area have been set up and the way they are managed. To me it sounds like putting in a rule for an arming device is just increasing any risks way beyond what we have now, which is lower than the arming device if managed properly. That is why many of us have not been using them. That plus you are adding more places for failure and more resistance in solder joints, wiring, and the arming device itself. KISS makes more sense.

bob branch

Igor Burger · « **Reply #23 on:** January 15, 2012, 07:12:24 AM »

Well ... arming device is not risk if done properly ... means short cables and used ONLY for arming and disarming, not for switching on and off. Howeever it is not so trivial thing how it looks. So I always recommend to beginners to make battery connectros easy to access and I do it myself the same way ... I connect battery on the circle, because I have them accessible from bottom of the model. The arming device is good tool if battery connectors are not easy to access, means when the battery must be installed and connected out of circle.

Regrading rule proposal - I think the rule should not dictate any device whatever it is (especially in case when we do not have so long experience yet), it should dictate safety itself, for example wording telling to attend the model whole time when the battery is connected shold be that reason forcing people to install either easy to connect battery connectors and connect them just before flight on the circe, or install the arming plug or another solution which we do not know yet (may be makers of ESCs will surprise us in near future :-) )

bob branch · « **Reply #24 on:** January 15, 2012, 07:20:32 AM »

Igor

I agree. Thanks for your input.

bob branch

Dennis Adamisin · « **Reply #25 on:** January 15, 2012, 08:34:56 AM »

Hmmm, sounds like part of the anwer is to put the arming plug directly behind the proellor - so it CANNOT be reached when the motor is running..!

Dean Pappas · « **Reply #26 on:** January 17, 2012, 01:43:06 PM »

Quote from: eric david conley on January 14, 2012, 12:09:00 PM

I'm using a Cobra 150A ESC, Scorpion 3226-1400kv motor and a 4s 5000mah 30c TP battery. I would be using a Castle ESC but they are not available right now. I don't know about adding a capacitor to the circuit, are there any instructions around for doing that? Thank you, Eric

Hello Dave,
Yes, shorter wires may be the answer. The inductive spikes created by the motor (especially on throttle-down from high RPM) will create high voltages that are not supressed by the battery because of the resistance and inductance of the long lead. The ESC will see the high voltege, though.

Castle even sell a capacitor bank PCB that solders onto the high current leads close to the ESC. It comes with online instructions.
http://www.castlecreations.com/products/cc-cap-pack.html
Curiously enough, even with the CAP-Bank CC say that 8" of additional lead length is permissible.
A full foot is almost certainly a problem.
Oh yes, the shorter, lower resisitance lead will also let you go faster in the high speeed part of the flight!

Regards,
Dean P.

jose modesto · « **Reply #27 on:** January 20, 2012, 07:49:18 AM »

Photos of MPI Maxx Product arming switch
Photo #1 MPI arming switch
Photo #2 complete electrical system
Photo#3 plane installation
Jose Modesto

Dennis Toth · « **Reply #28 on:** January 22, 2012, 07:30:35 AM »

Guys,
The arming plug that Jose is showing is also available from SharpRC.com. You can read a review in the Feb 2012 issue of Model Aviation, pg 14, their ad is on pg130. Nice installation package if you don't want to make your own.

Best, DennisT

Larry Wong · « **Reply #29 on:** January 22, 2012, 01:33:07 PM »

Here is what I use, and also use one inside of plane to plug battery in .

bob branch · « **Reply #30 on:** January 22, 2012, 03:50:22 PM »

Larry & Jose

Are you cutting the power lead you connect these plugs into shorter? Looks like a good number of inches added to the power cable if you do not. And if only in one lead do we get an unbalanced problem?

bob branch

Larry Wong · « **Reply #31 on:** January 22, 2012, 04:16:26 PM »

I try to keep it as close to the original Leigh as the black wire.

jose modesto · « **Reply #32 on:** January 23, 2012, 06:53:11 AM »

Bob i keep all wires as supplied by manufacturer. With the MPI disconnect switch,it does not require any wire modification. See second photo
For those that are well versed in electrical systems, you can modify the wiring as required. For me the weight savings from reducing wire length will be replaced by nose weight. No advantage to wire weight reduction.
Photo of Paul Walker's Nats Impact with MPI switch Installation photo from Kax Minato's site
Jose Modesto

Mark Scarborough · « **Reply #33 on:** March 02, 2012, 12:32:12 PM »

In looking at arming devices and the like, I recall discussions regarding "anti spark" devices as well. I am wondering if anyone has experience or input on this device...?

http://www.espritmodel.com/jeti-afc-anti-spark-connectors-4mm-75a.aspx

It looks as though it is intended to be used after the battery is connected, then you connect this with its built in resistor?

Igor Burger · « **Reply #34 on:** March 02, 2012, 01:08:59 PM »

This is Jeti anti spark connector, it is usual connector, just on front part is attached PCB with front layer connected to the back side by a resistor, it means if you connect that connector, you will touch first that part with resistor, and only then it connects with full contact, just you must connect that connector as last

I do something similar myself ... inside the heat shring is simply wire resistor and its wire is first thing which meets the plug when you try to connect it ... smple and well working :)look pic: