Prop suggestion

I'm just finishing up a plane that involves a new engine combination for me, and am looking for suggestions for a starting-point prop.
The setup is a Vector 40 (built from Brodak kit) with an O.S. LA .40 engine and a tongue muffler. I have not used this engine before.
I always test various props with a new plane, but am wondering where to start. Any suggestions?
--jt

John Thompson

The most-frequently recommended prop for an LA .40 is the 11-4 APC. Watch the hub centering; some have been a bit off. You can fill with epoxy and re-drill, if necessary.

John:
Around these parts, the guys are using 11X4 Power Points, or a "magic" prop, the 10 1/2 X 4 1/2 APC.
Spin it up some.

See Ya

I've also heard (from Pat Johnston) the 11x4W APC is a good starting prop.

If you can find one, you might also try the Tornado 10 x 4 3bl

While you are at it, you may wish to ask for the venturi size they are using. There are a number of different sizes that came with the stock engine, so just saying "what came with it" doesn't tell you anything. You can run a wide range of props merely by changing the venturi size.

Thanks all for the suggestions. This will get me started.
--jt

John Thompson

John,

Don't overlook Randy's suggestion--via Pat Johnston--of the APC 11-4W prop. Lots of people don't seem to know about the *W* versions.

Also, and I know we see it done a lot, resist cutting APC props back in diameter. I am too stupid about props to explain it, but *always* found this to be a slightly bad idea when dabbling in RC Pattern, am pretty sure it applies here as well.

The Real Question: Is Mike working on his Skyray 35? One of my goals for 2005 is to see him stomp you good in a CL Stunt event, and he cannot expect to fly the Dirtmobile at every contest...

I don't know is Mike is working on the Skyray or not, but I have no doubt that he will pass me up in scoring soon. He should be able to hit 443 with no problems! If he threatens, I'll just loan him one of my planes again; that should hold him back.
I have the new plane almost done. Just have to shoot some clear on it, bang the tail on the pickup tailgate a few times, scrape a wing on the garage door, and it should be ready! We will see how it flies -- always iffy, since I built it.
I actually think I have most of the above-recommended props in the shop, so I may be out testing soon.
--jt

>John,
>
>Don't overlook Randy's suggestion--via Pat Johnston--of the
>APC 11-4W prop. Lots of people don't seem to know about the
>*W* versions.
>
>Also, and I know we see it done a lot, resist cutting APC
>props back in diameter. I am too stupid about props to
>explain it, but *always* found this to be a slightly bad
>idea when dabbling in RC Pattern, am pretty sure it applies
>here as well.
>
>The Real Question: Is Mike working on his Skyray 35? One of
>my goals for 2005 is to see him stomp you good in a CL Stunt
>event, and he cannot expect to fly the Dirtmobile at every
>contest...
>
>Dan

John Thompson

>John,
>
>Don't overlook Randy's suggestion--via Pat Johnston--of the
>APC 11-4W prop. Lots of people don't seem to know about the
>*W* versions. >Dan

I looked on the APC website and the Central Hobbies website, and cannot find an 11-4W at either. Can you provide more info, PN, etc.? etc. Steve

If you want a serious prop talk to Windy and he will tell you about the Gator carbon prop. He is flying it on his every plane now including the Bomber.

LAST EDITED ON Nov-12-04 AT 06:18 PM (CST)
 
I have an OS 40 LA with a 12x5 prop on this 48" wing span stearman airplane. The RC carburator has been changed to a venturi using the same needle engine needle valve. The venturi diameter was copied from an OS 40 LA-S engine. As I recall the hole diameter is .282 with a 1/8" brass hobby tubing running across the center of the hole with a .040 orfic hole in the bottom side of the 1/8" brass tubing.