RCU Forums - View Single Post - Troubleshooting O.S. 46 problem

04-24-2009 | 03:11 AM

#13

DarZeelon

Senior Member

Joined: Apr 2003

Posts: 8,913

Likes: 0

Received 6 Likes on 6 Posts

From: Rosh-HaAyin, ISRAEL

RE: Troubleshooting O.S. 46 problem

Quote:

ORIGINAL: jeffsend

...I run an APC 11x5 or 11x6, O.S. A3 plug, Omega 15%. .... I use a home-made exhaust deflector, basically a piece of tubing that runs down and exits at the landing gear.
Just recently,mid flight, I noticed a loss of power and the engine didn't seem to be revving as high at full throttle. It was running ok aside from that. I landed and checked with a tach. It read around 11,000. I leaned the needle until it sounded like it wouldn't go any higher, and then backed off a bit and tached it around 13,300.

Jeff,

The A3 is the hottest plug OS makes and is, in general, way too hot for the OS.46AX, unless you are running 0% nitro, or flying at sub-zero temperatures.

This does not mean it will not run with it on 15% with this plug, but you will need to excessively richen the mixture (open the needles), for the engine to run properly...

The running costs of glow engines seem to be taken for granted, by manufacturers, retailers and modelers alike, under the false pretense that 'this is a hobby'...

In glow engines, the needles are the engine's primary 'ignition timing controls', during the run (the plug's heat range is one of the static controls).

A leaner mixture will ignite sooner, the flame would propagate more rapidly and it burns faster too.
So, closing the needles is the same as advancing the spark...

A 'lean-run' is simply detonation; not oil starvation...

So, you need to open the needles further, to compensate for the excessively high heat-range of the glow-plug, just splattering that expensive extra fuel all over the place, with no advantage whatsoever!

Change to a medium heat-range plug!

As to the deflector; it can 'come into tune'; causing either a gain, or much more likely, a real RPM loss.

I have seen a 1,000 RPM loss, in an MVVS .49 engine, as a result of installing a Hobbyco .35-.90 deflector...

Reply Like