The International Cessna^® 170 Association

Looking for suggestions for the best climb prop for a C-145 on a 170B.
Thanks, Marty

You will be looking for the 8040 Seaplane prop. Twisted to around 45"/47". You will find good take off and climb performance, but cruise will be around 90 to 100 depending on the twist. It was designed for floats, but has been approved for wheels with proper blessing from the FAA. Kenmore has the STC and you will have to make some other changes per the STC for wheels, gear or prop clearance. Ken Marrow in ID has one and can give you more details. Its a good prop, if you need the T/O and Climb performance. If you look back in the forum messages you might find other discussions about the propeller.

The original "climb" prop furnished by Cessna was a McCauley DM-7651. See the type certificate for additional data, for this and other props that need no special approvals or STCs. McCauley also offers this prop in other pitches, but there's a trade-off in cruise performance. (The MDM series is also available, and dia/pitches down to 7648 have been used with good results.)

8043

Marty,

I have a 7651 that I was saving for possible back country trips, but I'm really satisfied with the performance of my 7653 up here at 4000MSL (often 6500-7000 ft density). With my fresh overhaul, below 7500 ft I have to nudge the throttle back a bit to keep from overspeeding.

If you're interested the 7651, let me know. I can't find a photo of it to post but if you're inerested enough, I'll take one and post it.

Miles

The 80-inch props were originally intended for seaplanes that do not have ground-clearance issues. The 76-inch props meet the certification rules for ground clearance on these land-planes at gross weight in nose-low attitudes such as when making a wheel -landing simultaneously using heavy-braking. (Just want to be certain folks think about these issues when using longer props. Longer props require a lesser pitch to make up for the increased diameter which loads down the engine. The longer prop tips become less efficient at higher rpms due to their approaching the speed of sound, but at the beginning of take-off rolls they have an advantage at initial acceleration. But in this particular application, tip speed should not be an issue.)

8043 + 8.50's

Miles, I'm in the process of a major overhaul on 2604D as we speak (unfortunately I'm not doing it myself) and I maybe looking for a prop. If Marty is not interested in your 7651 prop and I heard you right that you may get rid of it....PM me a price and maybe we can work something out....

8043...8043...800's or 850's. I have a 650' strip...8043

Joe

I hear you Joe and I have been leaning that way, but I sure like my cruise speeds of 105 -108 mph with my 7551(which I'm getting rid of........what kinda cruise speed do you get with your 8043 prop and if I remember right you have a stock O-300?? And also what kind of a price can a fellow be looking at for an 8043?? I already have the 800's so it's the prop part I'm now changing....

Abe, I'm getting the same speed as you at 2450-2500. All planes being different, that doesn't mean that they will all get that speed with the 8043, maybe others with the same prop can chime in and an average can be taken. I wouldn't worry about prop clearance with an 80", I have the stock (flimsy) gear and have never had a problem. It's only a mere 2" closer to the ground than a 76". The tail has to go up a long ways to make the prop go down a little. If you get the tail up high enough to hit the prop, you're probably on your way over... I do have 800 tires however.

Joe
4518C

Thanks for the info Joe....I'm not concerned with the clearance as you say...I'm just doing some checking around to see which way will be the best for me and I'm leaning towards the 8043 for what I'd be doing most often....Next June at Minam you'll get to see the results....and maybe we can have a few exhibition flights with the different props and see how they each perform....

Sounds good Abe, I've seen them for sale from time to time in the 800-1200 dollar range used.

Joe

With the 8.50's, 180 gear, 8043, 0-300, - - - cruise 100 mph @ 2450.
I had to weigh this issue after leaving Alaska. For me (this is just me) if I couldn't find STOL strips to play on or be able to entertain the Ole Timers at my airport, flying wouldn't be near as much fun. AT ALL! The other issue is safety (this is just me). Ain't many people landed on their brakes like I have, clearance isn't an issue!

Abe wrote:....what kinda cruise speed do you get with your 8043 prop and if I remember right you have a stock O-300??

Stock C-145 @ 2450 RPM w/ 8042 prop I get 98 MPH on 26" Goodyears, 100 MPH on skis, 95 MPH on floats.