Ok you guys, don't boo me off the stage, I know this has all been covered before.
I've been using the search function, but I must say I'm a little overwhelmed with the seemingly endless list of do's and don't with gas engines.

I've just purchased a new G-26, and the 1/4 scale sopwith pup is almost framed up.
My first for both gas and anything 1/4 scale, and I'm excited.
But then I start reading posts and I get worried that I won't do something that I should have done, etc.

Primarily I'm concerned with RF interference.
The posts I've read seem to agree that using a Bosch style plug cap will go a long way towards curing this.
I haven't sprung for a pcm radio, but I'm encouraged by the philosophy of "pcm isn't the way to fix it because it's a band-aid approach".

I intend to make very sure my range checks are effective.
But I'm worried that I'm going to send a thousand dollar airplane into the ground because of ignorance about RF interference.
So I would like to know if there's just a basic check list of do's and don'ts when installing gas engines.

Thanks a hundred times.

Don't make it too hard. The easiest way to check for RF or EMF interference is to build the plane, turn the radio on, start the engine and see what happens.

Seriously, until you do this, you don't know if you'll have interference or not. I have built and flown 3 gas-engine planes: a Giant Stinger with a G-62, a 1/4 scale Dr.1 with a G-38, and my current 1/4 scale Dr.1 with a G-23. I have not experienced any RF interference at any time. I've used both Futaba and Hitec FM radios. I used the standard flywheel ignition, plug wire and resistor plug that came with the engines. None of the servo wiring has any type of choke or interference filter installed. I kept all engine electricals (including the kill switch) in front of the firewall, and all radio electricals behind the firewall. I didn't use any other shielding.

Maybe I'm lucky, but it works and I haven't had any problems.

Dr.1

Good advice !!

Dr1Driver.......... how bout adding those Jasta kites to your model profile ? I wanna see the gas 3 wingers.

I need to do that, sturtz. I'll work on it.

Dr.1

The first rule is: Keep you radio equipment as far from the engine as possible (I.E. don't mount a throttle servo in the engine compartment).

The second rule is: Use a non-metal throttle pushrod (Like a Nyrod, or Sullivan Gold-n-rod, etc. ) as RF can travel through a metal pushrod.

I've always done those two things and never had a problem.

I just put some up. Take a look, Sturtz!

Dr.1

Also, when you do your engine on and off range check, make sure that there is no more than 10-15% difference.

First off,,, sorry for rattling on to Dr1 about planes on your engine thread Bosch.

But,,,,, wow .... those tripes look killer !! Takes a real scale rc pilot to handle one of those. Nice flyby pic.

Thanks, Minn and DR1.
What about engine mounts (for the firewall)?
Anything special about that?

RTK, what do you mean when you refer to the "difference" in engine on vs. engine off range checking?
Difference in what?

Bosch232--What I mean is this..Let's say you can walk 100' away from you plane with the engine off before any glitching or lock out. Then with the engine on and varying RPM's you can only walk 50'. That is not acceptable, you should be able to walk at least 85', some people say no less than 90% or 90'.

As for mounting,, I always hard mount them and have never used any type of soft mount.

The 100 foot number that RTK provided should not be considered a "hard" number. That was for comparative purposes only. You should be able to obtain considerably larger distances. Closer to 200 feet if all is well, engine off or on.

Personally, I wouldn't accept ANY difference in the range-check distance.

Gassers are really easy to mount. Most have 3-4 holes or mounting ears in the rear of the crankcase. These are usually threaded and designed for bolt-through from behind the firewall. That's a real pain to install and remove. I drill these out for a #8 or #10 socket-head cap screw and lockwasher, and use blind nuts behind the firewall. I've done a G-62 that way. No problems. I've never soft-mounted an engine. If the prop is balanced properly, I see no need in it.

Dr.1

Thanx Pat,,,I should have mentioned that it was only a comparative number.

Dr1,,,I do not like to see much difference either. ALL of my range checks are well over 100 yards and usually closer to 200. This also exceeds the manufacturers recommendations.

Thanks for the input, fellas.
If I may, let's take the conversation a step further.

Let's say I collapse my antenna and do a range check and find there is interference with the engine running vs. engine off.

What's the first order of business in tracking down the problem?
(as in, what's the most common cause/first place to look?)

By the way, in the back of my Futaba 6exa manual, it says "20-30" paces for a range check with a collapsed antenna.
I step about 2.5 ft per pace, so that's about 50-75 feet.

The 20 to 30 paces is something is something that has come up quite a few times before. If that's the best you can do, don't fly until you can at least double it.

The most common cause of radio problems in gassers is never common. It runs the gamut from losse and rattling nuts and bolts to old and worn out wire connectors. It's never one common thing. I take that back. A rather common problem is user reluctance to spend the money needed to buy good, high quality products when they can get "bargain" parts for less. The next most common thing is the whining and ignition blame that ALWAYS takes place after the crash. Always.

Sorry, but in far too many years, those are things that have been a constant.

Pat

First, check for metal-to-metal contact. Always use nylon clevises with metal horns. You can use metal clevises with nylon horns. Make sure all nuts and bolts are tight. I that's not the problem, move the radio wiring around. Be sure to use a resistor plug. Keep all engine wiring in front of the firewall and all radio wiring behind it. Use a nylon rod for throttle control, not a metal wire. A last resort would be to shield the firewall.

Dr.1

Keep any metal part, rod, wire , etc completely away from the muffler. Mufflers and RF noise have a long sad history.

Thanks for your patience, guys.
This helps me quite a bit.

We (my friend and I have the same 1/4 scale planes) have the Sopwith's almost completely framed up.
Ready to hinge the surfaces now.

Then it's on to installing electronics, and then covering.
All servos will be new metal geared, and all extensions are new.
In fact, every single component on my plane will be new (G-26 included) except the Tx and Rx.

I'll post in a month or two when I maiden it.

hello all im surprised that no one mentioned that the spark plugs in the magnito engines is a resistor type, and should never be replaced with a non resistor. Usually the number on the plug will have an ( r) in it. This also applies to the c&h type ignitions. In the past I have had ni-cad battery packs cause interference in the radio when the engine was running. These were on both ignition and reciever packs. Had one pack that would run the ignition ok, but when hooked up to the radio system, would not work at all, dead. Go figure. Just make sure you have new or well maintained ni-cad paks in your equipment. Hope this helps Jack