Motor for Pathfinder?

[Terry Bolin]

Hi guys, I am building a Profile Pathfinder by Brodak and wonder which motor would be better. I have both, a OS 46LA and a OS40LA motor. What have you used?  Post  pictures of your pathfinder.
Thanks, Terry

[Willis Swindell]

Terry
I would use the 46. You might want to add 1/64 plywood down the sides of the fuselage to stiffen it. My Saito 50 would twist the stab but it flew OK.
Willis 

[Crist Rigotti]

46LA.

[Allan Perret]

Use the 46 unless you want to compete in P-40.  Mine has a Saito 40.

[Randy Powell]

Small Block V8?

Go with the 46LA

[Mark Scarborough]

Now that there is no line size penalty for the 46,,( not that I would let that matter anyway) go with the LA 46, my setup I flew on three airplanes last year and others also use,, (ok I stole it from Pat Johnston) 10-22 fuel sith 50 - 50 castor synthetic, a .275 to .280 venturi, an APC 12.25 x 3.75 prop. Mine typically wanted to be launched at about 9800 rpm. GREAT power and drive. and really not a finicky setup. However, One of the three 46 I used really wanted to have about 4 or 5 oz of additional castor to maintain its setting through the flight.

[Dennis Vander Kuur]

an APC 12.25 x 3.75 prop.

Mark,
How did you manage to run a 12.25 inch prop? The biggest prop I could run is 10.5" diameter. Did you make new longer landing gear?
DennisV

[Mark Scarborough]

Dennis,
Maybe its your wheel size? I dont fly a pathfinder though several around this area do, I fly similar sized ships. I know that Pat has worked with a couple of them and gotten them to use the 46 with the 12.25 prop. to my knowladge, none had to make new gear. Then of course most of the guys here are using 2.5 wheels or something along that line i THINK. for me,, the fantastic performance of this prop and engine justifies any means needed to be able to run it. longer gear, sure thing no problem,,
just by way of additional info, I tried all the reported wonder props, 11x5, 11.5 x 4 ,, everything i could bolt on. NOTHING performed as well as the 12.25 stock. I fly at 3000 feet and 95 degree temps at home, and then at sea level at contests, it performs equally in both environments. The biggest single thing that I gained with this prop was consistancy. with the other props, if you miss the perfect needle setting by a tiny bit, you can vary the fuel consumption by a minute or more either way. ( one characturistic of the LA46 we have noted)with this prop that seems to be greatly minimized. Not to mention fantastic drive off the corners and tension overhead

[catdaddy]

Mark,
How did you manage to run a 12.25 inch prop? The biggest prop I could run is 10.5" diameter. Did you make new longer landing gear?
DennisV

In district 8 we trim this prop down to 11.75 with the LA 46. It's killer on the Pathfinder and Cardinal.

[Dennis Vander Kuur]

Terry,
Either engine should work fine. The LA .46 is a sweet running engine with a bit more grunt than the smaller LA .40. However, I have been flying my Brodak kit-built Pathfinder for the last 5 years with an LA .40 and really like it. The APC 10.5x4.5 prop works very well with this engine/plane combination. I picked the LA .40 because I use the Pathfinder to compete in the P-40 class at contests. I use it even at contests that have been changed to "P-91" or "Profile-Unlimited".
You're going to have a lot of fun with the Pathfinder. It is one of my favorite models.
DennisV

[Mark Scarborough]

Rick
I am curious as to why you needed to trim the prop down, everyone here that flies that combo just LOVES the stock prop,,

[catdaddy]

Rick
I am curious as to why you needed to trim the prop down, everyone here that flies that combo just LOVES the stock prop,,

I did it on the advice of Doug Moon and found the engine ran better. Doug knows his stuff. It may have something to do with our geography and weather. I keep a couple stock ones as well for flying in other locations, but for the most part use the trimmed down version.

[Terry Bolin]

Thanks to everyone for their help. All good information. It's nice to pull from other fliers rather than make all the mistakes myself. Most of 'em I have already forgot anyway, I'll have to relearn them.