Take a look at these props. Can anyone tell me why the 12x4 is tapered so differently at the tips? It seems that it has less surface area than the other of the same pitch.

http://www3.towerhobbies.com/cgi-bin...?&I=LX1555&P=0

http://www3.towerhobbies.com/cgi-bin...?&I=LXMJ90&P=0

The 11x4 that is pictured is an 11x4w

The "W" stands for WIDE

Is that on the hub somewhere?

Yup

The W or wide props also have a thinner hub and on some engines you may need to add another washer to make them fit or tighten down.

Minn,
That looks like a normal APC blade shape to me, not the wide blade shape. (I use the 11x4 sport prop on one of my planes, fwiw).

I also happen to have the APC 12x4 sitting around (I was going to try it on my tigermoth, but didn't), and for some reason the APC 12x4 does have a really narrow blade compared to most APC sport props.

I've no idea why APC make the 12x4 like they do. If I had to guess, I'd say it was to better suit a target engine or use that I'm not aware of.

Fwiw, wider blades will generally put more load on an engine, and will provide more thrust at lower speeds. They also provide more "breaking" effect on a downline.

So props intended for 3D work are usually wide blade, shallow pitch. Racing props are usually narrow(er) blade props with higher pitch. (I'm generalizing).

So, different props for different uses. For flying around, it really comes to trying a bunch of props and trying them to see what you like.

The 11 X 4 is not designated as being a wide by APC

It sure looks like a "W" though

Thge prop on top, the dark one is a 15X4W and the one on the bottom is a 15X6 standard. Easy to see the difference and when you see them together you can see the difference in the hub or center size.
Gene

Square tip props like the Master range often generate more prop noise esp. in the air.

We have very strict noise limits at a club field in the UK and Scimitar shaped tip props turning at the same rpm almost always came out 1 to3 db quieter.

We don't have restrictions at our field and I love the buzz of the MAS props

Both props shown are APC. The dark one was just soaked in Rit Dye to match a plane. I often dye a number of props in the size range I think will work on a plane. I had the dye left over from tinting canopies. Like 8 said, sometimes prop noise is cool.

APC sells several prop diameters with a very flat pitch and wide blades for low speed high thrust applications

Some have a "W" after their size