I would like to seea design or where to buy a servo actuated switch. I desire such a switch to shut off power to an electronic ignition module for a gas engine. Thanks Wayne

These days we have an optical kill switch that is much better and simpler to install. They are priced at around $20.00 and most any of the hobby shops that advertise in magazines or on the web sell them. Just look around for OPTICAL KILL SWITCH and you will find one.

Sometimes choking a gasser will kill it once its warmed up.  Not reliable in all engines though.  But if you already have a choke servo...try using it to kill the engine.

Optical Kill switch would be the best way to go though as there is nothing mechanical to ever fail.  This is my opinion of course.

+1 on the optical kill for an EI

www.rcextremepower.net has them

Years ago we made a servo operated kill switch, it has nothing to do with the choke at all. It was just a servo attached to a switch and the switch was attached to the ground strap. Today I still use an on off switch for my ignitions and nothing has changed, when on, it just grounds the plug/ignition like it always has. What the OP wants is to know how to make a kill switch operated by a servo. The servo arm just attachés to the switch arm. No mystery but it went out with bow ties and high button shoes. They tended to often create a RF problem that was hard to eliminate. Shazam, three decades later someone comes up with the same idea only does it electronically, calls it an optical kill switch and it's a new super duper item that you must have or your plane will fall out of the sky! Most the time I just use a manual switch. I have had a reason to have an optical on a plane once but that was it, once. I like the optical kill switch but it is not a must have item. For under 20 bucks they are cheaper then the switches I use so why not buy the optical.
To the OP. This is the beginners forum. Beginners tend to use glow or electric and not gas engines. When I have a question about any of my gas or glow engines I go into the gas or glow forum and ask my questions. I often find the answer just reading through the threads or doing a search.
The question about a servo operated kill switch is something I haven't heard even at the field during the BS sessions in the peanut gallery. Glad to see someone recalling the good old days. We have moved on from there though.

Well i'm glad he asked the question here as i'm in need of a way to kill my gas Quadra 42 engine before it gets on the ground (or right after touch-down).

I have had this engine a lot of years and it runs OK but it does not want to idle at a very low speed and it is a problem at my home field which is a one way approach and a fairly short field.

Posting a picture of the model i have it on........Was told what the name of this model was and did not write it down and have forgot
the name. (looks like a big Stixbut it isn't ).

If i could kill the engine remotely if the need arises that would be nice.

BIGMIG

For some reason it won't let me load any pictures.........?

Optic kill switch!!!!! that way if you loose power to the airplane, then ignition cuts off.

Iuse the old analog kill switch. Eccentric wheel on a servo beside a micro switch. In this case it was all made with materials on hand. A great use for once-crashed servos that aren't quite control surface trustworthy.

Nothing against the fiber optic switch - Iuse those as well.

Fly:


Die:

Do they work on Mag engines?? The Quadra looks like maybe it could use a carb kit and then a tune up so it will idle down. Maybe even go through the linkage and tighten it up so the throttle closes all the way.
Mig, the Quadra is still used quite a bit, I saw a lot of them at IMAA events. There are a lot of people in the gas engine forum still using them that can be of help. I still use Zinoah engines with mags. I really do like them as well as electronic ignitions. I even like spring starters on gassers too. There are tons of threads about Zinoah in the gas forum too.[8D]

The switch system Charlie is showing is also what we used to do for on board glow drivers, they work better then the new electronic systems and work great on smoke systems too.

{Pushing his walker into position} Iremember long beforedigital trims, digital mixesand digital end-point adjustments were available and folks did all the same features with manual solutions. It's good to keep your hand in.

But boy, Isure like digital end point adjustments and stick exponential. ;-)

Thanks for the responses. The analog switch pictures are great. I am wondering how the optical switch functions. I will call the manufacturer and ask that question. Price is good. I was at the field yesterday when a large gas plane would not idle and consequently did not want to land. I have just built a gas plane and realized the possibility that I could get myself in the same situation and decided to add a kill switch to the ignition. I am also concerned about the danger of landing a plane and taxing off the runway while accidently hitting the throttle. If something causes the plane to idle to fast, I would like to be able to kill the engine on the approach and dead-stick-it to a landing. I will pursue buying the optic switch. Sorry, about not using the right forum but I still consider myself a beginner. I will do better next time....thanks again</p>

Some people like the optical switches and some don't. I have had a bad one and almost lost my plane. But I am sure this was an exception, they seem to work fine for most people.
The gasser can be killed with the throttle, just like any glow engine. Take that idle screw out and you can always use your trim to adjust a high idle.

If you must, send me a PM with address and I'll mail you a miniature limit switch - no charge.

By the way, I now use Tech-Aero IBEC's exclusively. Aint technology wonderful?

Al

Hmmmm, not always. Some Walbros have a dead stop on the throttle butterfly where it can't close completely regardless of where the idle screw is adjusted

Charlie the cam actuated killer is a good one. Simple and cheap

To the OP, consider the Tech Aero Ignition battery Eliminator Circuit, IBEC, rather than an OptoKiller. In addition to giving you the ability to kill the engine remotely, it also is used to arm the CDI remotely. You will have a single battery and switch to drive both the radio and the CDI. This gizmo is around 40 bucks and is well filtered so that your radio won't experience RFI. It also allows you to tailor the voltage that drives the CDI. Oh it saves you areound 5 ounces of weight too since you no longer need an extra ignition battery and switch.....plus another couple ounces if you decide to use a servo driven, mechanical device..... I use the IBEC. The IBEC weighs less than 20 grams BTW

I've used these on all of my 1/5th scale rc cars and trucks and they saved me more than once.
http://www.davesmotors.com/s.nl/c.88...t.A/id.3569/.f

These are great because if the Rx voltage is too low it wont even let you start the engine, or if it gets low the engine dies, also if connection is lost it will kill the engine, and i can use a channel on my Tx as an on/off switch. I'm sure the airplane variants are just as good/usefull.

My quarter scale Decathlon used a magneto ignition with a micro switch mounted n the engine bay. A non-metallic push rod actuated tot he switch to short the magneto to ground. Any ignition noise was thus kept in the engine bay. That engine is now being converted to electronic ignition and the same system will be used except the NO contacts will be used to kill the igntion rather than the NC. That system is as reliable as the servo and radio system that operates it. That radio system is entrusted with the flight of the airplane so it is equally good to kill the engine.

You're really better off with an optical kill. If the battery dies in the reciever the ignition will shut down. There's no way flying a gas plane I would want the motor running if the receiver battery dies or the radio goes into failsafe.

Also, if our linkage has a problem or the servo dies from vibration you can still kill the engine.

We used to listen to high quality 8 tracks, personally I prefer the sound and picture of a Blu-Ray, because its available to me, its cheap, and its better than some of the time honored way of doing things. Not that they dont work, but this really is better in almost every aspect.

I have used the RCATS system. Same as the optical type, but uses a relay.