Help with kill switch options
 

Guys,
Having already spent a fortune on a DA50 and DP Edge, I'm trying to decide on a kill switch, or way to kill the engine when I land.
Trying not to break the bank. What are you guys using, and what are my options?
Any info on setting up would be very helpful. Thanks.

Help with kill switch options
 

I use a JR charge switch just like you would use for the receiver on and off. I also have the throttle set so when I pull the trim back it kills the engine by closing the butterfly.

Help with kill switch options
 

same here...just as PCM said. That JR Charge switch is a good switch for this purpose. The throttle butterfly on the 50 should also kill the engine if set to close all the way when the trim is pulled all of the way back. Alot of guys use that charge switch for the IGN and have had sucess with it. That's the main reason I use it, is because it has been proven over time to work well. Be sure to wire it correctly, and put it in a place where your helper can see it, and can get to it quickly if needed. I like to put mine on the left side of the airplane as close to the cowl as possible on the side of the fuse. It's good and solid there because that first former is strong. While it won't destroy the bank account, it's not the cheapest switch either, but you want reliability there as this item is not just a on/off switch, but a safety item as well. :)

Help with kill switch options
 

I use a ignition power switch, a choke servo, and I can kill my engine with reduced idle. The only thing I don't use is a ignition kill switch that is controlled from the transmitter.

Help with kill switch options
 

I use a choke servo, and a throttle servo. I set one of the switches on my futaba 8u as a throttle kill. It works great and is better than having to back the throttle trim all the way down. There is a fiber optic kill switch, that's in line between the battery and the ign box which directly cuts power to the ign box. It's the trick way to go, but they cost about $70-80 bucks. One thing you can do with your 9C radio is use the slide switches on the side. One for ign kill, and the other for high / low idle, or for choke servo.

Help with kill switch options
 

The British have an association like our IMAA, but for extra big models called the Large Model Association. Their website is http://members.lycos.co.uk/LMASiteUK/ Very intersting stuff. One of their rules, which is tested at every event, is that turning off power to the transmitter should result in the engine shutting down completely. Starting from there, the cut-off for an engine becomes more than the mechanical problem of getting the thumbs on the switch on the model: which may in fact be at 500 feet over the crowd. Not strictly what this thread is about, but I can describe my solution to this with off-the-shelf stuff. I use a HiTec Eclipse 7-channel transmitter. Computer radios aren't for everyone, but this one work well for me in that the throttle movement is set with end points, and an even lower completely closed setting is associated with the throttle "cut" button on the transmitter. Hitting that button, instead of futzing with trim, closes down the butterfly and the engine stops dead, though there is still spark. Same thing can be done of course with throttle trim, but on my Eclipse I do not use throttle trim at all. Where the system becomes "failsafe", is my use of Multiplex receivers. I use the IPS-Mini 9-channel ($90 US from Hobby Horse) Instead of the PCM strategy, which requires a transmitter signal to do anything, you can set the exact servo positions on the Multiplex receiver, that should be actuated when transmitter signal is lost or corrupted. Set this - on the receiver! - for the "cut" position and the engine goes off when the transmitter goes off, and the Large Model Association rules are met. Another option, easily built, would be for the throttle pushrod to also disconnect the circuit to the ignition when travel goes that far (just a couple of strips of brass sheet that push apart would do fine). Anyway, I think the Multiplex receivers have been missed by people in all the hubub about PCM. It's ironic that HiTec has PCM now on the Eclipse, but also owns Multiplex. On these Multiplex receivers, a simple jumper-looking gadget is provided. You get any servo to the point you want it, pull the servo cable out of that channel, and put this jumper in then out, and the receiver is set on that channel. No fancy transmitters required, and really no fancy receiver, and you have a failsafe condition for when the signal is lost or some moron turns onto your frequency. It may be that the default you want in this condition is engine idle I just use this scenario to show how to get to the Large Model Association's rules with no special hardware or additional switches. In fact, the method people use of shutting down with trim on a non-computer transmitter can be emulated with the Multiplex receiver: just trim down before using the jumper. Then just switch off the transmitter and the engine quits. Long-winded. Sorry....I do that.

Help with kill switch options
 

Hi All,

There is an RC switch available at www.rcatsystems.com for $20.00. Giant Scale racers have been using it as a kill switch for years.

Kai

Interesting
 

Sounds simple enough. Are the racers using electronic ignitions like the ones in giant scale? If so, this is much less expensive than the Custom Electronics type of switch that uses fiber optics.
Sounds simple if our gassers could use something like that. The thing to keep in mind is that we should at least have something other than throttle trim for shutting the engine down. This is second only to the PCM users making sure that the fail safe is set to the idle position_bob

Help with kill switch options
 

I use the same setup as Geistware. . choke servo, throttle back to super low idle and it cuts off, and ignition switch. All three kill the motor, the choke and ignition on-off switch being the fastest and most sure.

Help with kill switch options
 

In regards to how the Giant Scale racers are doing it there are two answers. First, on an engine with a magneto, the RC Switch is used to ground the coil to the case, instantly killing said motor due to lack of spark. Secondly, if the engine is running an electronic ignition, the RC Switch is placed in series with the positive or negitive wire going to the ignition battery.
Then again, if the racer is using glow fuel without ignition, you have to close off the butterfly valve.

Kai

PS I'm not familliar with the fiber optic switch you mention. Are you refering to an optically isolated switch?

Help with kill switch options
 

Kai,
On the Giant Scale Aerobatic planes we don't like to use servos near to the motor because the leads could pick up interference and feed it back to the reciever if the ignition shelding breaks down. Using this RC switch sounds like a great Idea - but isn't it succeptable to the same type of shielding failure?
This is why we like to use the optical switch. No way it can transmit interference if radio components are mounted 12" away.
RickP

Help with kill switch options
 

RickP,

So you have an actual fiber cable going to the engine area and use that to trigger a relay or a fet or something? It then has to have it's own battery.

Some of those aerobatic birds are getting huge so I would worry about long leads too.

On Cliff Sands Knight Twister, he had a 4.4ci with a magneto and we had an RC kill switch in the engine compartment. Never had an interference problem and the motor was very close to all the radio gear.

Kill Switch
 

It doesn't get much cheaper or simpler than this.

Help with kill switch options
 

Big Bird,

It may not be "much simpler" but the RC switch is cheaper and easier then what you have pictured.

Kai

kill switch
 

You might want to go to www.morrishobbies.com and look at their fiber optic kill switch . It is set up similar to those other switches that people posted but it isnt mechanical strictly electrical on its own channel.

Help with kill switch options
 

The Morris page is showing the electrodynamics switch that we are talking about.

What is the consensus on this question...

Switch
 

I don't understand what all the confusion is about.
I kill my engine with the throttle servo trim and a manual switch wired to the ignitionm operated by a separate servo on its own channel. I had to use it once when my throttle linkage broke and I couldn't slow the engine down at all.

Came in for an approach, killed the engine and landed no problem, fixed throttle linkage and was back in the air in about 30 minutes.

Help with kill switch options
 

There are some that "feel" better knowing there is something other than a mechanical link to a kill switch of some sort. Lets face it servos fail, servo mounts break, firewalls come loose changine throttle position etc. In those instances we have little chance of shutting the engine down. There are posts in this thread where some flyers have more than two ways to kill the engine. Just more insurance, that's all.

Help with kill switch options
 

That is all true and probably good advice.

I try to check my plane out thoroughly before flying to make sure nothing like that will occur. Although it is impossible to foresee all events, it does make me feel safer knowing that I can kill the engine two ways.

I also subscribe to the theory that the more complicated one makes something, the more chances there are for failure. I learned a lot about hardware and failure modes from my time in the nuclear industry. I was an Instrument Technician and later an Instrument Engineer and one of the greatest concerns about safety was failure modes. The best proven way to ensure the least complications was the old addage, K.I.S.S. and preventive maintenance.

Post#14 Diagram Question
 

I don't build rockets, so bare with me here. If my set up were like the one in post #14, would I have to in effect peel the wires apart on my switch harness and splice the switch in that way?
For some reason I can't make the connection. Thanks_bob

Help with kill switch options
 

Hi Bob,

If your existing setup is a manual kill switch only, and you wanted to add a remote kill switch (RC-100 or other), then yes, you would need to cut into the wiring harness on either the red or black wire (not both). The RC switch wires would then splice into the area where the wire was cut. Hope this clears things up but if not respond and I will try and elaborate further.

Regards,

Kai

Help with kill switch options
 

That should do it. If I used your diagram as a guide, I would want to cut the "+" wire between the existing switch and the ignition plug.
Also, it doesn't matter which wire I use coming out of tht RC-100 on the switch end or the module end. In other words there is no polarity. Thanks for the fast reply_bob

Help with kill switch options
 

Bob,

You are correct on both counts.

By the way, an added bonus to hooking up the RC-100 in the way you are doing it (with an electronic ignition) is, that if the receiver power is not on, the RC-100 is open and will not allow the engine to start.

Kai

Help with kill switch options
 

So Cool! Thanks again_bob

RFI?
 

The RC-100 electronic switch looks simple, but if the switching and RX halves are not isolated, won't there be RFI issues? How many of you are using it for ignition? The company is advertising it for ignition, but actually shows photos and wiring schematic for a smoke system on/off.

There appears to be ignition power (and RFI) flowing through one side of the RC-100 switch via the spliced-in connection The other end of the very small RC-100 switch plugs directly to your receiver.

Sounds like this could lead to an RFI problem.


1. totally optical system, or
2. a servo pushing on a LONG nyrod to a mechanical switch

either #1 or #2 sounds like a better way to guard against stray RFI with an engine kill switch.

Help with kill switch options
 

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The RC-100 electronic switch looks simple, but if the switching and RX halves are not isolated, won't there be RFI issues?
-RCAddiction
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It is simple and the two halves are isolated, it's commonly referred to as a relay.
But yes, there may be RFI/EMI interference problems as with any device plugged into your receiver. If I was flying a 40% 3D monster I would be worried about all that servo extension wire too. The fact is every application has many possible solutions, some better then others. It's nice to have options and the RC-100 is an elegant solution for those needing an RC auxiliary switch, weather as a kill switch, auxiliary light switch, smoke pump switch or whatever.

Kai

Re: Post#14 Diagram Question
 

Bob, NEVER split the wires on your switch harness. The diagram in post #14 shows a separate swithc that controls the power to the ignition module from the ignition battery.
On a standard magneto ignition engine all you have to do is bring a wire from the primary of the magneto to a switch and then to the engine case. You can either make it ( the switch) manual or servo operated. Mine is servo operated from the transmitter so I can kill the engine by simply using my Channel 5 switch on the radio.

Re: Re: Post#14 Diagram Question
 

Hi Jim,

Unless I am mistsken, Bob appears to have an electronic ignition module setup that uses a designated battery to power its operation. The only way to stop the electronic ignition from operating is to "open" the battery wires with a switch of some sort or by disconnecting the battery altogether. One could wire an adapter with the RC-100 in it that goes between the ignition module and the battery if they do not want to cut wires.

In your post, you are talking about a magneto setup, where the ignition is powered by a magnet triggering the coil and so forth, hence spark. I don't quite understand how Bob would ground out an electronic ignition setup as one does with a magneto.

In regards to all the other concerns about EMI, no circuit is immune to interference. Look at all wires as antennas. They can either pick up or give off energy based on what is being transmitted down the line, dependent on frequency and other factors. Knowing the design of the RC-100, it would be very difficult for it to have any energy communicated through the battery leads being switched and onto the servo wires on the enclosed circuit. Hence, if you have problems with energy on the battery wires to your ignition, this shows some inherent EMI problems with the electronic ignition and I'd be worried about things without an electronic switch. Inserting a switch or any wires of any kind could magnify a pre-existing problem.

Regards,

EMI. RFI
 

Thanks for the comments.

However, how close do the contacts in a relay have to be to conduct EMI or RFI? This is only a small air gap, right?

I thought there was a rule about keeping something carrying an ignition signal at least 12" away from something that can carry it back to the receiver?

Re: EMI. RFI
 

Think of the separation as an insurance policy. You could place the receiver right on the ignition module and if all the shielding works, you probably won't have a problem. However, if the internal shielding fails, you develop a crack in the ignition module case, your resistor spark plug fails, or your grounding fails, you will most definitely get interference. With the separation, it would all depend on how severe the interference is, but you stand a much better chance than not having any.

Re: EMI. RFI
 

First off, The contacts on the relay aren't the only separation that you have between the servo and the battery. The RC-100 setup is a relay that is triggered by a signal pin on coming from a microcontroller. The microcontroller senses the incoming pulse from the signal lineand flags the relay open or closed. Basically, it would be hard for any energy to come from the battery, conduct down through the relay, through the microcontroller and onto the signal line. If interference were present, it would be from the sheer field strength of any emitted frequencies that couple to the servo lead. Like I said before, if there is noise present in the battery line, you have bigger problems. So back to your original question - how far do the relay contacts have to be? Theory could tell you, but one would have to know the RF energy present. The more energy, the less the distance, etc

Distance does equal insurance as stated in previous post. The RF energy falls off the further you get away from the source.

Michael

Here's The Latest
 

Over the weekend I got a chance to install the RC-100 in my 40% Carden Cap with an older 3W 140. It's just below the most forward part of the canopy which is about 8" from the ignition module. I didn't build this plane, but the ign battery and throttle servo are within 6" or so of the module. Anyway, the switch works like a charm ;) I have it hooked to JR single conversion receivers, and activated by the snap button. I recently moved all my kills to the snap button and like it alot. The RC-100 is a keeper and I am satisfied. Thanks RCATS!