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John,

 

The most common props for the Coupes are the McCauley 1A90CF or 1B90CM.

 

The common pitches for Coupes with the C-85 engine are:

 

7146 extreme climb prop

7148 normal climb prop

7150 "normal" prop

7152 "cruise" prop (unless you're too heavy whereupon it may not get you up
to cruise speeds - not a problem 1260 lb. or less - can't tell you how heavy
you have to be to start having problems)

 

Common cruise speeds with a C-85 at 2400 rpm achieved from these props, not
taking into account the variation from increasing or reducing drag from
average:

 

7146 - 100 mph

7148 - 104 mph

7150 - 108 mph

7152 - 112 mph (maybe)

 

Per Aircraft
<http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0
/36fc39ae4a59c7418525673e0067ba7b/$FILE/a-718.pdf>  Specification A-718, the
governing document for the C and CD models:

Engine limit for all operations: 2575 rpm (red line)

Static rpm at max permissible throttle setting: not over 2225, not under
2025

Diameter not over 71 in., not under 69.5 in.

No additional tolerance permitted

 

This should be all your A&P needs to know to judge suitability of the prop
for your plane.

 

Best wishes,

 

Ed Burkhead

http://edburkhead.com

ed -at- edburkhead???.com          (change -at- to @ and remove "???")


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