OS46FX

[Ken Culbertson]

Finally got all of the inards of my 46FX replaced and re broken in.  First flight was Saturday.  Whomever told me earlier that the FX had a "bit" more power than the LA needs to look up the definition of "a bit".  I have a beast on my hands.  I fly a 60" 650Sq 18% wing on a 52oz ship with an 46LA for now.  Flies great on 63' lines (e2e) with a 5.5 lap.  I dropped in the FX and it turned a 4.0 on the same 11-5 prop I use on the LA and that was running a fast 4 cycle which is about as slow as it wants to run smooth.  It has more raw power than some of the .60's around here.

I am not much of an engine man so I did what research I could and found nothing on the 46FX that was not part of one of my earlier posts so I am asking for some advice.  I am building around this engine and as of now the plane will have 690 squares 22% airfoil and a target weight around 60oz.  That is only a slight increase over what I flew it in Saturday.

So, how do I harness this beast?  I have no clue as to props, etc. on larger engines.  I know the 11-5 is not right but what is? The rest of the story is a ST NVA in the primary with about a .270 venturi and a rear NV, 10% Wildcat fuel, and no additional head gaskets.

I am open to anything - Ken

Follow Up - Never thought to search on the 46AX and I did find some advice there.  Interestingly I also found the 46FX mentioned but none of them were on the 46FX Search  - Hummm....

What I seem to have found is a 12-4 prop, a .250 venturi and a big-ass plane.  This is "Bear" country and we have quite a few running anything from .50 to .70 engines with and with out pipes but none of them are running 4.0 laps so,  I am guessing the thicker wing will help.  I can go to 68' lines but that would only take me to a 4.7 or so.

Thanks - Ken

[Lyle Spiegel]

OS FX both 40 and 46 have reputation for "peeling" of the Ni plated layer on cylinder liner. Of course RC guys use less oil than we do, so that could be part of the issue. You can find replacement P/L with true hard chrome chrome ABC from Just Engines in UK. Very reasonable price . The 46 P/L is a drop in to the 40 size case as well as the 46 case.
If you drop 46 P?L in to a 40 case you will need to use the head for a 46, and the proper size head gasket.
Lyle

[Ken Culbertson]

The first thing I would do is go out to 69.5' handle to thrust line and, I have seen 3 blade CF props with less than 4 pitch.

I just cut down some 69' to 63' Aghhhh.......

Would restricting the venturi with hose material slow it down some?  I know double BB engines are designed to run lean but how low can you go with pitch before
you cross the line?  I would think 3 is about it.

Ken

[Steve Helmick]

I just cut down some 69' to 63' Aghhhh.......

Would restricting the venturi with hose material slow it down some?  I know double BB engines are designed to run lean but how low can you go with pitch before
you cross the line?  I would think 3 is about it.

Ken

Try the APC 12.25 x 3.75, use the stock muffler, and decent amount of oil in the fuel. Something like 20% total oil with 15% Klotz and 5% castor would be where I'd start. It should run fine on 5% nitro. Restricting the venturi with pantyhose mesh is always an option, but the thing I don't like is that it stretches like crazy, leading to an inconsistent degree of restriction. Set the airspeed with prop pitch and engine load with diameter & number of blades. Steve

[Brent Williams]

Why the big desire to switch from a consistently great, easy running engine(LA46) to a much heavier, much higher RPM, much more powerful engine(FX46) on a 52oz plane? 

Randy Smith has experience with the 46FX, but you sure don't read about the 46FX as one of the go-to newer RC engines for use in control line planes.

Sell it to an RC guy.  Make life easy and get (stick with) something that has carries a known recipe and a reputation for successful operation in the stunt realm.

[Ken Culbertson]

Why the big desire to switch from a consistently great, easy running engine(LA46) to a much heavier, much higher RPM, much more powerful engine(FX46) on a 52oz plane? 

Randy Smith has experience with the 46FX, but you sure don't read about the 46FX as one of the go-to newer RC engines for use in control line planes.

Sell it to an RC guy.  Make life easy and get (stick with) something that has carries a known recipe and a reputation for successful operation in the stunt realm.

I put it on that plane to see just how much power it had and how it responded to CL.  I have no intention of replacing my LA but it is really hard to fly a pattern with a break in stand.  I have only been back at it since January and all I have is two planes.  This engine is slated for #3.  It seems to have as much as power as some of the piped 60's around here.  It runs well and if I can harness it, I intend to use it.  The RC guys want the AX and this particular FX had already been converted to CL when I got it.  Maybe they were not popular because they were very expensive and now that they are out of production for about 10 years that makes them hard to find parts for.  All of the reasons not to get one but, if you already have one it is completely different.  It is worth asking those that know if it can be tamed or just how big and heavy should I go if it can't be tamed.  I am not a 4-2-4 fan on a big ship.  I run a fast 4 on the 46LA and I plan to do the same with the FX if I can get a Venturi, Prop, Line combo that gives me a 5.5. on something about the size of a Strega. To do that I need to get where I have it mounted now to fly at least a 5.0.  Man at 4.0 it is not a pattern, it is a 6 minute pull test.  If I can't do that then it is EBay

Thanks - Ken

[Brent Williams]

All valid reasons. 

Contact Randy for some advice on taming that beast.

[Ken Culbertson]

All valid reasons. 

Contact Randy for some advice on taming that beast.

I will, he is supposed to be making me a crankshaft insert for my 35s that I will bet he has forgotten about due to the NATS!  Time for a reminder.

Ken