Can anyone advise me on a good prop selection for my SIG 4* 40 powered by a Supertigre .40 engine?? This is my first build since the trainer and I am down to the prop. My hobby shop was a little unclear about a selection.

Thanks,
Lamar

A 10x6 prop is always good for a .40 engine. Beginners tend to be a little hard on props, so you might want to buy a spare. The brand "Master Airscrew" is a good choice because it will withstand a minor strike with the ground. It is black plastic. Wood props probably perform better in the air, but break easily. I'd buy the master airscrew 10x6.

A 10x6 on a ST .40 will scoot right along. Mine turns 13,800 with a MAS 10x6 and I have to fly at 1/2 throttle most of the time. You might also want to experiment with 11x5 & 12x4 sizes. These will give a slower top end with more thrust to haul you out of trouble...

Also consider an APC 11X5. I used this prop on my ST 40 in a trainer and I like the thrust without excessive speed.

I would go for a MAS 10-5 prop. Tough enough to handle minor prop bumps on grass fields and will give you more oomph when you need it to get out of tough situations. [8D]

A 10x5 will let a ST.40 over rev, I think...

Hi Lamar
I checked Tower Hobbies website. In the description for the Supertigre 40 they suggest prop sizes: 9x7, 9x8, 10x5, 10x6, 10x7, 11x4, 11x5 [sm=confused.gif]
breakin: 10x6
On a new engine I would go with one of the middle range props 10 x 5 or 10 x 6 and see how it performs after the engine has been broken in. I normally run a 10 x 7 on my 40s. As for brand of prop I like APC Sport propellers, they are grey nylon with carbon fiber reinforcement. They hold up very well and do not flex as much as common nylon props.
My 2 cents worth.

Dale

The ST .40 and the 4* 40 make an excellent combination, For ease of landing I suggest the 11-5 to start with. I like wood props for sport flying. APC types are excellent for competition but don't break easily enough when they encounter something besides air.
Once you get everything going well, try the 9-7 for speed and then a 10-6 for whatever, and maybe an 11-4. The 11-4 may over rev during certain unloaded maneuvers, thus making a lot of prop noise.
The 4* likes to float. Lower pitch props with a decent idle will air-brake it just a bit making landings easy and smooth. Some years ago we raced the combination with 9-7 props and landings took a bit more application of fine talent.

Enjoy the machine. The wing is fragile however it will hang in there for sport flying. When you get really seasoned on it cut one rib-bay off each wing outer panel. You will step up a couple rungs on the ladder.