Randy'
You indicated that you did try all these different shapes, widths and cambers. So what ones worked and what didn't?
Brett,
You have explained the impact on pitch that the different prop have and that is good information for those using them. Could you tell us what the depth of the undercamber is on the different props - 1/64; 1/32; 1/16. How much did you sand in on the one made up?
The ones I have made up have 1/64" max depth sanded in.
Best, DennisT
Dennis the more important question was which ones worked best, and were easier to setup, and which ones had the largest "envelope" that it would fly in, nothing is a simple answer, but the slight U/C props worked best all over the country , with differant seasons and weather. They had the widest "envelope " of any of them, and performed with the best of them. that said you REALLY need to match the prop and the style of the prop to the motor, for example, the wide heavy under cambered 13 x 4 worked wonderful on the PA 65,(near 1/8 inch of U/C cut into it ) the load was just right, and that U/C prop was very draggy and requires a lot of power to turn, and cycle. it worked best in a very strong 4 cycle, with just beeps of 2 at the top. The 61s had a very hard time pulling that prop, so it needed to be trimmed down quite a bit, at least an inch.
The 3 blade slight under camber worked best on the 51 and 61 at 12 inches, These blades are much higher A/R than the wide 2 blade (between a 64th to a 32nd in cut into it) .
The same profile U/C 3 blade in a 13.75 x 4.5 or 14 x 4.5 worked very very well on the 75... and still does.
The slight U/C 15 x 4.8 2 blade ( 1/32nd to near 3/32 U/C cut into it) is killer on the 75, however you must have a plane that can handle that prop, or you need to trim it to 14 inches.
The piped 40s that were strong, worked very very well on a Narrow 3 blade at 11 inches (maybe 1/64 in UC), very consistent and very constant speed. especially in the high winds. The other prop that was almost universal was the Bolly slight under camber 12.25 x 4.25 trimmed to between 11.2 to 11.7. that depends on what motor you were using. You need to really be careful NOT to overload the 40s with prop, you will find it harder to needle and will get richer as you take off, again making it difficult to hit the needle setting just right , also many found it would wind up in the winds if over propped and would be very touchy to get a break right. with too much of a break coming at times, trimming the prop down closer to 11 inches worked much better for the less stout motors and would result in a much more consistent runs, with almost every motor These ran in the 11,000 or slightly over range, and would also work very well in a solid 4 cycle, or 4 with just a beep of 2 cycle at the tops.
Tip shapes vary wildly, I found a fat scimitar tip worked very well for my use, it seem that it had the best characteristics of the slightly longer prop, with the less load of the smaller cut down prop , a swept back slight rounded tip, sort of like the VECTOR wing tips worked well, and like the fat scimitar shape, was quieter .
I will try to write more later, this could take many hours to tell most of this.
Randy