dirtstrip wrote:Here is a US company's online calculator.
http://www.culverprops.com/pitchselection.htm

I've run some different prop diameters and rotation rates through this calculator, but end up with different results when I plug in the same numbers on a different online calculator over at Pponk's site http://www.pponk.com/HTML%20PAGES/propcalc.html . Then over at the Hoverhawk site's calculator, it has commentary that suggests that between .88 and .92 Mach is the redline and tip speed should be below .88, while Pponk's site suggests that between .88 and .92 Mach is the most efficient tip speed.


Is there any definitive, reliable tip speed/prop pitch calculator out there? I want to put a fairly big prop out front on the new RR, and utilize all 6300 engine rpms available for the best climb out performance. Any of you guys have any suggestions?

parameters I have used so far are:

2 bladed prop
max engine rpm: 6300
available gear box ratios are: 2.16:l, 2.29:l, 2.59:l
average ambient temp 90F

There. I've up and done it....cracked my IVO prop after locally made replacement bungees failed and dropped the plane to the ground. Now I'm really looking for a new prop, something other than an IVO.

I bought a 3-blade Kiev for my short-tail S-7. I love it. It's quiet and smooth, and easy to adjust.

Any of you guys ever tried or heard reports back about the Prince P-Tip propeller?

Seems to be many positive customer comments on the Prince website. If I understand it correctly, it changes about 3- 4" of pitch automatically, depending on how much load is put on the prop while moving forward. For example, if the prop is turning fast but the plane is moving slow (like in a steep climb, higher load on the prop), the ends of the prop bend slightly, changing to a climb pitch. But when the plane is at level, high speed (less load on the prop) then the prop shape goes back to a higher pitch for cruise. Also, the swept back tips are claimed to conserve the air better and the result is an increase in air volume. For example, a 68" Prince P-Tip is alleged to move the same amount of air volume as a 72" standard design prop. This translates into better thrust right?

I'm a little skeptical about a prop that regularly bends, but I'm open to any experiences you guys might have or know about with the Prince P-Tip.

I've ruled out Warp Drive due to its higher weight and inertia.
IVO is also ruled out since mine cracked and I'm looking for a better alternative for short take-offs and steep climbs.

Powerfin is still a contender for it's low inertia and paddle area, and Kool Prop is a contender for the same, plus anti-vortices tips. Any comments on the Prince P-Tip from anyone here?

No experience with the Prince.

The Kiev is money. Smooth, great performance, light. Looks sexy. It's got real bits of panther in it, so you know its good.

I'm going with the Prince P-Tip. It's a little different design, and pricey compared to IVO and Warp and that genre, but it seems to have the qualities I am looking for, and some remarkable claims worth testing out. So I'll let you all know how it works after installation, maybe post some test flight pix or vidz.