Thanks Terry.

This one's a bit flatter than 53 also, judging from the RPM's. Goes fast, but pulls poorly. And it has a vibration in it I've neved liked. Think I'm gonna shop for the longer prop.

Gump

GumpAir wrote:....I was looking for this info. I have the O-300 and 7653 on the current POS I'm flying. My experience exactly with this prop... It doesn't climb well, doesn't cruise well, doesn't do much of anything well. I was gonna send it out to the prop shop next month with the annual, but now I think I'm gonna shitcan the thing and put something else on there.
Gump

I had a McCauley 76-51 on my C170 & it performed pretty good- climbed OK & cruised OK. I wouldn't have wanted any more pitch. The seaplane prop is an 80-42, the 170 version of a supercub "borer" prop (82-41). Never tried one on my 170 but they're supposed to be just the ticket for STOL op's.
I'd like to try a borer on my C150/150 to see just how much better the takeoff & climb is. You lose a lot of speed capability but you gotta give up one thing to get another- no free lunch.

FWIW here's a formula for ciphering out the relationship between prop pitch & speed. It assumes 100% efficiency but oughta come pretty close for most of us, esp if trying to see the performance difference between two different prop pitches.
pitch x rpm / 1056 = mph. OR pitch x rpm x .000946 = mph

GumpAir wrote:Thanks Terry.

This one's a bit flatter than 53 also, judging from the RPM's. Goes fast, but pulls poorly. And it has a vibration in it I've neved liked. Think I'm gonna shop for the longer prop.

Gump

Just wanted to mention, my C-145 Cont had harmonic dampeners on the crankshaft so only certian props could be used with that engine or it could damage the engine.

Yeah, I have an O-300B. Got to do some research to see what's approved.

Quick look at TCDS shows only three approved props with that engine.

Gump

I just replaced the 7653 on my 170 with a 8042 seaplane prop. It pulls harder on take off and climbs a lot better as well. Cruise speed dropped from 120 to 108mph at 2550. I don't mind the loss in speed though. Anyone want to buy a 7653?

What about a manual pitch prop? The kind that you can change from a curse you climb prop on he ground. Are they really expense buy or over haul? Or is it just not many engines allow them? But that would be the way to go to get the best of both worlds, short of a controllable pitch prop

TrevDog wrote:What about a manual pitch prop? The kind that you can change from a curse you climb prop on he ground. Are they really expense buy or over haul? Or is it just not many engines allow them? But that would be the way to go to get the best of both worlds, short of a controllable pitch prop

Are you talking about ground adjustable, or in-flight controllable? I would love to have something like a controllable variable-speed or even 2-speed prop. But don't know of anything available AND approved. It would indeed be the best of both worlds.

Or you could always get an Aeromatic. http://www.aeromatic.com/

That's funny-- I deleted my (negative) comment about Aeromatic props before posting. I've heard too many unfavorable things about them. They sound like a good idea, and maybe they are if they're properly set up, but they are automatic not controllable. I'd prefer something that I select the pitch on-- I don't need the high elevation or something else out of my hands deciding to throw the thing into coarse pitch at the wrong moment.
The C170 TCDS lists 2 different controlable props, as I recall one being a McCauley & one a Sensenich, but I've never heard mention f either one of them elsewhere. Guess that means they weren't much of a hit.
I have seen some electrically controlled props such as the Ivoprop for experimentals. A good idea, but looking at the wimpy blades on one of those makes me think that it wouldn't be much of a performer for STOL work. There was some sort of controlable prop available on the Stinson L5 but I don't kow much about it-- Beech-Roby maybe?

I've got a 72" Hartzell on my IO-520 Cessna 185. It is over TBO on the year limit and I can't decide to strap on a MAC/MT or just hold off on spending the money right now. I like to play in the backcountry and am just curious how much of a difference a 401 or MT is going to make. My 520 just got a new top and I'm planning to go IO-550 in about 500 hours which will probably be two years.