Help with prop selection
 

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;)

RE: Help with prop selection
 

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.

RE: Help with prop selection
 

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...

RE: Help with prop selection
 

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

RE: Help with prop selection
 

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]

RE: Help with prop selection
 

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

RE: Help with prop selection
 

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

RE: Help with prop selection
 

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. :)