Excellent LA46 Prop!

I'd been flying my 53oz Vector (not the kit - the older 630 sq in version) with an LA46 with wrap around header and CF pipe spinning an APC 12.25 - 3.75 cut down to 11.75". It was OK. Revving just below 10K at launch, it would tick between four and two cycle in level flight, than go to a hard two in manuevers. Not bad.

For the heck of it, I tried a Brian Eather 11.25 - 4 three blade CF prop. I'd had this for ten or twelve years, having tried it without much success on OS 40VFs.

Much better than the APC! The engine now "backs off" into a four cycle on the back side of the rounds and diving portion of the wingover and hourglass. It operates at a higher rev and the engine seems much happier. I guess since the prop is not overloading the engine, the whole system now responds better to the changing load in the pattern. I may not understand it . . but I like it!

It's among the best 4/2/4 pipe runs I've experienced.

Glad I didn't swap that Eather prop away.

Kool Rick....What fuel, lenght of lines, lap speed, ALL of the goodies
I keep info for later use.

scott

Scott:

The Details:

Fuel - Powermaster GMA blend, 5% nitro with 1oz AeroProduct fuel additive. It burns about 4.25oz of fuel per flight.

Lines are 62' (eye to eye) of .014" solids. Lap times are 5.4 seconds, but I'll probably bring it up to 5.2 with a small tweak of the valve.

I'm using an old Smith/Werwage pipe that was made for the 40VF. I've had it since the early 1990s.

It's not exaclty Champagne Stunt on a beer budget, 'cuz I've still got the $90 pipe, and $45 prop . . . but it's great performance for relatively short money. The extremely light, and smaller diameter Eather prop was much better regarding yaw issues than the heavier and larger APC. Some things are really worth the big bux.

Having said all that , I still look forward to dropping Randy's PA40 Lite in the nose. I friend just bought one and wants to try it out. I just happen to have the ideal ship for it!

If the plane trims out and is a superb flier, I'll buy a PA40 myself.

Rick Campbell

Rick,

Thats some interesting data. I've been running an LA-46 in a 50oz Time Machine 50 this season. I've been using the APC 12.25 x3.75 cut down to 11.75 for the last sixty or so flights. On Sig 5/20 I launch at 10100 rpm with exactly the same run characteristics you were getting with your APC setup. Big difference is I was running a big Art tube muffler instead of pipe.

I'll have to look into one of those props, as I'm not 100% satisfied with the break characteristics on the APC, as you found out with yours.

BTW, with a side exhaust motor, do you still measure pipe length the same way? From the gloplug to the baffle?

Steve:

Regarding pipe length, I found out (the hard way) you have to measure the actual exhaust path from the glow plug. This nugget comes from Randy Smith, of whom I asked the same question.

I was shooting for a length of about 18.5", and measured it like would a rear exhaust engine . . . wrong!

The actual length of that setup endned up being close to 20" - not cool.

Having corrected the pipe length, I then flew several more flights before discovering the Eather 11.25 - 4 3B prop.

I asked Randy for more propeller suggestions and he said to try the Bolly 12-4 2B.

Igor Burger uses an Eather 12-3.5 UCT 2B prop on his piped LA46.