Building my first gas GS Warbird and have no experience with gassers. I have been told that the kill switch must be installed forward of the firewall or else it will cause interference with the radio. Is this true? Because of the contour of the bottom of the cowl and fuselage there is not an inconspicuous place to put the switch unless I place it behind the firewall. What about the throttle servo, can it be placed forward of the firewall?

People have a lot of opinions on this. General practice is to keep anything connected to the engine as far away as possible from your radio, and that includes kill switches, charge jacks, batteries, wires, etc.. I've seen some magazine articles where the author has placed the throttle servo on the firewall next to the engine. All I can tell you is that in my latest plane, a Yak 55, I've had to place my receiver and rx battery pack at the very rear of the radio compartment, and have the engine switch and charge jack at the very front, giving me about 12-15" of separation. On tests, just having the charge plug dangling in the radio compartment reduced my range significantly. My throttle servo, connected via a nyrod, is about 12" away from the engine ( I had started with it about 8"). The bottom line is that each installation has variables, such as the condition of the spark plug lead, type of plug, ignition system, magneto, etc.. You just need to install it how you like (without cutting holes I'd suggest) and then test the range. If you have a signifcant drop in range, depending upon your radio manufacturer's recommendations, then try moving the components.
Hope that helps.
Sam

The "rule of thumb" is to try and keep all Ignition related wiring, switches, etc. at least 8 inches away from anyhting related to the radio.

As for the throttle servo. Some guys have no problem mounting them directly on the firewall, or to the engine box. I do this too and have little or no problm. On some of my planes I've used fiber optic isolators to seperate the throttle and ignition battery......
What kind of engine do you have? Magneto or Electronic?

A friend of mine showed me a Great Planes kill switch that is not as intrusive as the one I had so I can install it forward of the firewall without ruining the appearance of the plane. I will be sure to keep the radio gear as far away from the engine electronics as possible. Thanks for both of your help.

Also consider the ElectroDymamic fiber optic kill switch. The system it fool proof and works like a charm. Nice to have the LED on the side of the plane to tell you the system is Hot too.

Pete

Its not as fool proof as you might think. I had one in my H9 Cap 232 using PPM and if I got the slightist radio glitch it would interrupt my ingition causeing a dead stick. The glitch was so small the it could not be seen. For a long time I thought I had an engine problem. After spending a lot of time on the fuel system, ignition battery and wiring and mixture, I disconnected the fiber kill and my deadsticks went away.

Gang doing by first gasser. Is it recommended to put a servo activated kill switch in the planes along with a toggle switch. I was planning to use a radio shack micro switch with a small servo in the plane along with a mini toggle in the engine compartment. Is this over kill? I here some fields require the radio kill system. What kind of problems will I have if any? Need help!!!!!!!!

Yes you need TWO ways to kill the engine. The first is the power switch to your ignition battery that is manually operated. The second can be the fiber optic switch(mine works fine) or I have seen a servo to the choke or a separate kill switch that is servo triggered either set to a switch on your Tx.

Pete

Why not skip the kill switch and set a kill switch from the radio to close the throttle. That reduces the component count, increasing reliability. Just my 2 cents

The reason that we shut down the ignition is in the event the trottle becomes "stuck" or the linkage becomes disconnected. It's a Safety thing..........

Exactly!!
Last year a friend was flying his Giant stinger with no secondary kill switch and his throttle link came off. The engine stayed at about 1/2 throttle and he had to fly the plane about 40 min to burn off the fuel. BUT this was his 2nd flight that day and he was REALLY SWEATING about his batteries going dead before the engine cut out. Well the RC gods were kind to him and he made a great dead stick landing but he learned a BIG lesson that day as did I.

You must have TWO ways to kill your engine.

Pete

A 40 minute flight at 1/2 throttle! That's a long time. I wonder what engine and tank size he was using? Was that his second 40 minute flight that day?

Travis

Can't remember the tank size but it was a G62 and he had two batteries. 1st flight was short as he was tweeking the engine.

Pete

Just found another source for kill switches: [link]http://www.rcatsystems.com/rc/electronics.php[/link]

I've been using the electronic kill switch from RCAT that Richard posted above. So far so good. One on a DA 50, the other on a BME 50, I'll need to get another one for my ZDZ80.

It is small and lightweight and at around $20 or so, costs even less than a servo.

I use the Electro Dynamics, and the RCAT. They've both worked fine, and I like them both_bob

I see that RCAT offer three but only one is fiberoptic the RC-100FO and costs 49.95$.

Can't using the other RC100 and RC110 units still put you at risk of RF interference since your hard wired from the ignition back to the Rx?


Pete

That's not so. I am using the RCAT non fiber switch on a 40% Cap for two years now and it's flawless. It's a simple and inexpensive switch that works fine on gas engines.

I had emailed RCAT about the interference issue and Michael directed my to this FAQ site.

http://www.rcatsystems.com/phpbb/viewtopic.php?t=4


Will try one in my next gas project.


Pete