the reason to install a kill switch
 

had forgotten about this til i recently stepped into gas........the airplane was tough to land as the idle changed drastically........the ending tells the whole story.
the member is a great guy, so no pun intended to him, but it's reality that makes one realize why a kill switch needs to be installed.

enjoy

http://www.youtube.com/watch?v=krQ2w...layer_embedded

RE: the reason to install a kill switch
 

I have had a throttle servo die, engine come loose and another time the linkage had come off. All those times made much easier due to cutoff.

RE: the reason to install a kill switch
 

Geez Eagleburger
I hope they didn't happen all at once :D

Oh - I just realised - it was probably "that 4 lettered product" that shook it apart :)

I prefer to use cutoffs for safety. (I only use the smartfly one these days) The only time I have ever needed to use one was due to my own error in an assembly. Nowadays, I also leave the throttle return spring on the engine.

RE: the reason to install a kill switch
 

What is that expression that defines an action that is repeated over and over expecting a different result even though the conditions have not changed? Seems that flying a pattern until the gas ran out and then landing dead stick would have been a better approach.

Sincerely, Richard

RE: the reason to install a kill switch
 

I think a properly tuned engine prior to take-off would've prevented that mishap. I'm very jealous of that mile long runway. Some modelers have all the luck.

RE: the reason to install a kill switch
 

Fresno is a nice field. Flew there once with the TFC gang at a Huckfest.

Ignition kills are a personal choice but they will not compensate for failing to tune an engine correctly or setting an idle when the engine is too cold. Only education can do that. Over sensitive controls make for some pretty nervous moments in a first, or later, flight as well. Setting up with rates helps alleviate that situation.

Never, ever, tune a cold engine or set an idle on a cold engine. Always set up your throttle linkage where the idle trim can kill the engine, even if you have a kill switch. Learn and know the linkage travels required for the carb to function properly. There's really no excuse for doing things wrong. I'm sure the flyer in the video had some tense moments but I'm also sure a lot of learning took place on that flight.

RE: the reason to install a kill switch
 

I use optical ignition cutoffs on all my large gas warbirds. I program the cutoff to operate from the spring loaded trainer switch on my transmitter so that at any time I can cut power to the engine, irrespective of the state of throttle servo, linkage or trim. I do also properly tune my engines and setup my linkages and trims so that I can shut off the engine using the throttle trim or throttle cut function programmed to a switch, but when I taxi in after flights I always shut down the engine using the optical ignition cutoff.

In this particular video, the plane looks tail heavy, so that complicates things. With a tail heavy plane, I think I would prefer to try to land under power rather than flying it around until it runs out of gas and then dead sticking it, especially since it sounded windy. I don't know about the throttle linkage setup on this plane, other than that there was no throttle trim left (you can hear the pilot say that in the video), but a remote optical kill switch would have been convenient in this situation. On that one pass where the plane was on the ground, the engine could have been killed right there and it would have been fine.

Adding an optical ignition cutoff is a personal decision and it does add another failure point, but for me if properly installed (isolated from vibration) the usefulness outweighs the added risk.

-Ed B.

RE: the reason to install a kill switch
 

i agree with being able to kill the engine both ways...ignition and or kill switch.
i have always set my planes up to be a fool proof as possible (hey, Dad was USAF veteran so i learnt:D).........
in this case, a kill switch would have been the best choice, and from what i have seen it is a smart choice for the flyer.
funny thing is though, i watch Bob all the time at the field and he is very cautious in tuning his engines to run right. this one just got away for some reason.

RE: the reason to install a kill switch
 

Well, I've not yet completed my first gasser, but it didn't take much convincing to realise that an opto kill was a wise investment! on the bench i've set it up on a separate switch to the idle down (throttle cut) so i can set a closed barrel with ignition off for choking my fg20, or with the engine running just use the idle down switch to enable me to experiment with finding the minimum throttle barrel opening for lowest stable idle. However, once i've found the ideal throttle barrel position for idle, i will set up the opto kill to work on the same switch as the idle down function. so with one switch flick it will kill the sparks and enable low throttle stick to close the barrel completely - belt and braces!

Just the thought of flying round an overpowered large gasser on full throttle, waiting for a 40 min tank to empty is enough to make me sweat - Even more serious is the possibility of a receiver failure or radio battery/wiring fault leaving you with no radio control and a running engine! Imagine how far a big plane will fly in 40 minutes - thats the beauty of the opto kill switch. Loss of receiver signal to the switch automatically cuts the engine - at least she ain't gonna fly away..............

RE: the reason to install a kill switch
 

So what is wrong with using the throttle cut button on the Transmiter...you know the TX? http://www.rcuniverse.com/forum/js/f...n/confused.gif?????

RE: the reason to install a kill switch
 

It only works on glow engines????????

Naw, that's not even a little bit true. It's all I've ever used, and all I've ever needed.

RE: the reason to install a kill switch
 

Well I think the guy did a good job with what he had to deal with. Maybe ony a prop damaged, it could have been a lot worse. A remote ignition kill would have helped though.
Aaron D.

RE: the reason to install a kill switch
 

the pilot is our cheif test pilot and overall the most knowledgable member who goes out of his way to help anyone.
why the engine went into such a high idle was baffling, and the Tx ran out of throttle down trim.
personally i have all my 2 stroke Jett's and YS engines set with the throttle kill switch setup. never failed me yet.
properly done i agree that hitting the switch on a gasser should work as well.
a kill switch is basically a safety device right?

RE: the reason to install a kill switch
 

how about a servo on the choke, what the change's of both going wrong ?just a though:eek:

RE: the reason to install a kill switch
 

Fact is, there is really only one reason that a Throttle kill such as an optokill is ever needed. and that is because of human error (Bad throttle programming, Bad linkage installation, Bad engine installation, poor battery quality, poor receiver installation - the list is near endless on how we can get it wrong on our toys). That video shows me a human error of some sort - asssociated with the throttle setup not allowing the throttle to close completely. Maybe the linkage shifted after takeoff or maybe it was not right in the first place - could be a number of things but they all point to human error of some sort.

As has been pointed out - they don't work on most glow engines.

I prefer to use them on my big toys so as to minimise the engine damage when I make an installation or setup mistake. Having said that, not all of them have got them installed.

My experience is that radio failure (human or electronically caused) will usually result in a "positive engine stop" pretty quickly. Or a softer one if the failsafe is set to bring the throttle back to fully closed.

RE: the reason to install a kill switch
 

It doesn't always work. I had a case on a GP Giant stick this summer where it turned out the servo tray was not glued in properly. I had gone over it like all my planes with ca on all the structural stuff but did not do the servo tray. So I was up flying and next thing I know it is stuck at full throttle. Every time I moved the throttle the tray would move not the throttle on the engine. So I flew it around to a location I knew I could make a safe dead stick and hit the engine kill. With out it I would have had to fly it full throttle until it ran out of fuel. I always install some type of secondary engine kill for those unexpected occasions. A little extra safety never hurts. Normally I don't use it, I just shut it off with the engine cut off on my tx.

RE: the reason to install a kill switch
 

What if the throttle servo fails in flight? In that situation a throttle cut/down function or trim down won't help, but an ignition kill can, so it can help in situations where there is not human error involved.

-Ed B.

RE: the reason to install a kill switch
 

Simple fact. Those that feel electrical engine kill devices are needed will always find another reason to have one. Those that don't feel a need for them will not use them.

I have one way to shut off my car. From there only external means are possible. With a full scale aircraft I have two ways, cut the fuel or cut the mags. I have not found a way to make everything I do in life perfectly safe. If I had I would have never had a car or motorcycle accident, or cut myself, or burned myself, or tripped over an item on the ground, or fallen off of a skateboard... You get the point. I won't wear a helmet while skiing, snowboarding, riding a bicycle, or any other activity that did not require one while I was young.

RE: the reason to install a kill switch
 

While i can agree with both sides, including the human error issues, I never set up anything gas over 30cc without an opto kill switch. For about USD 20 why leave it out? Even if you are the best, most careful guy out there i still recomend using one. the simple reason being that when there is a loss of Rx battery power it automatically kills the ignition. Can you imagine a 50cc or bigger plane that rockets out of control full throttle into fellow pilots or spectators......

Yeah i know you must check and recheck your Rx batteries and power setup BUT things happen, IF it ever does to me i have peace of mind at least my engine will cut too.

I know soemone who lost a 30% with DL50 on the front. Lost rx battery power, it flew full throttle into a chicken shed across the farm. TotalledEVERYTHING even the DL50was in about 15 pieces. With an opto kill it wouldnt even have reached the chicken shed. Imagine it had hit some of the workers......................

that said i never wear a seat belt while driving..................never drive over the speed limit either ....................

RE: the reason to install a kill switch
 

I think its a no brainer, an opto kill adds another layer of safety to the most dangerous part of a plane - the big shredder at the front.

If your not convinced think of it like this:  whats worse to be hit by??? A fast gliding heavy plane that'll impact like a sledge hammer - or the same plane going three times faster with a two foot rotary cutter at the front. If you lose the radio link, this is the question you'll wished you'd have considered earlier!!!!!!!!!

RE: the reason to install a kill switch
 

this is copied from the 'other ' forum, call it what you like. Sometimes s&*t happens and an opto kill is essential...........

"A run away 50cc just happen yesterday at our field. With no way to kill the engine the owner had to chase the plane around the field trying to catch it. It would have been funny if not for the fact that we all had to hide behind our car incase it came into the pits. Cause of problem: throttle servo linkage came off."

RE: the reason to install a kill switch
 

aussiesteve,
If you look at our local regulations(MOP's) you will find that all spark ign engine powered aircraft have to have an ign cutof switch that can be operated by the transmitter to make them legal. I have seen a lot of people turn up at the field with gassers and then have a problem with landing because the engine increases the idel in flight because the engine is just not setup correctly.

Cheers

RE: the reason to install a kill switch
 

Sometimes a kill switch is added as a matter of convenience as well as safety.
Fully closing the throttle doesn't always shut off my MVVS 26cc gas engine which makes the transmitter's throttle cut feature ineffective. It may not stop even when pulling the throttle trim back until the servo buzzes while it "crunches" the carb throttle plate hard against the stop. This engine idles reliably at 1340 rpm and flipping the throttle cut will sometimes slow it to 990 rpm where it will keep running for over a minute. Bad linkage, poor tuning, really? Or, could it be that some carbs have that little notch at the edge of the throttle plate that prevents the air from being completely shut off?

RE: the reason to install a kill switch
 

Yes - you bring up a good point on the rules for Heavy models. (Rules that were only recently changed).

[link]http://www.maaa.asn.au/maaa/mop/procedures/MOP015%20-%20%20Heavy%20Model%20Aircraft%20Inspection%20and% 20Oper.pdf[/link]

Absolutely. Rule 6.3.1.6 on page 8 of the Heavy Model MOP very clearly states that the Engine must be able to be shut down from the TX by an alternative means to the throttle control. No question of it.

Whilst off topic but in a similar vein, Rule 6.3.1.3 also clearly states that Battery redundancy is required.

However - those rules only apply to aircraft above 7kg dry weight. There are many planes out there with Petrol powered (and Glow powered) engines that are almost but not quite that weight (Including quite a few "50cc'ers").

As these are a 3 year certificate here (Does anyone keep a plane flying that long? - any pointers wil be well accepted please :)) There are still a number of planes out there that hold valid certificates that were issued under the old rules. There are also no doubt some glow powered planes in the category, I wonder how they will implement this.

As I stated in my one of my earlier posts on this. I do use kills - certainly on anything 50cc and above and on a few of the airframes below that size. I have done so for a long time. Thing is I know of people that have been killed and others that have been seriously injured by getting hit by small (0.40 size) planes - my old club President was one of them - he has steel plates in his skull (an possibly not much else :D) due to a 40 size hitting him when it went off air.

Where and how does the line get drawn?

I do support the use of killswitches that are TX activated. I also only use the best quality ones because I want them to work as intended - every time. There are plenty of examples of why I use that policy but it is really up to the individual in most cases. A faulty one can kill an engine and I have heard of a couple of cases where they failed to "on" (no brand names mentioned). Maybe we should use 2 of them in series in case that happens.

RE: the reason to install a kill switch
 

There are three basic types of 'kill switches' out there, and have different applications it seems.
 
1.  The original "magneto grounder" which is an on-off switch with one end on magneto and other end to ground, when closes/activated the magneto is grounded and spark generation ceases thereby killing engine. 
2.  The "optical kill" for electronic ignition set-ups.  Works good but I tried once using one to ground a magneto engine and it didn't work, my electronics genius cousin suggested the switch it intended for lower voltage/power applications only.
3.  The High Power "Optical Kill" which can be used for electronic ign setups that most of us use on bigger engines but also works as a magneto grounding switch if you want to run it this way.  I found one of these a few months back at TBM and it solved a problem I was having where the std 'opti-kill' wasn't cutting-it (no pun intended)

I think a secondary kill system is neccesary and desirable.