Prop vrs, speed

[matsuthunder200]

I have a good ?? for everyone. I am going to change my prop
Now i have a sin, 76 inch with a 38 pitch. I want a 40 or 41 pitch.
now i cruse at about 77 mph Is there a formula On pitch vrs, speed like for every Two deg of pitch you get a __ increse in speed.....
Dose anyone have a 40 or 41 inch prop what do you cruse at......
Thanks in adv.
Lance

[swoeric]

Re: Prop vrs, speed

any plans for the old prop? ......what rpm are you cruising

[astjp2]

Re: Prop vrs, speed

a 74-43 can cruise 100kias, each inch of pitch is good for around 50 rpms of static, this is approximate. Your 76" seaplane prop is a good candidate to repitch. Have Merill Field propeller twist it. He will also check for coning of the blades. My prop was coned foreward 1/4", they creep foreward over time. Tim

I would love to have a 76" prop to replace my 74".....

I have a good ?? for everyone. I am going to change my prop
Now i have a sin, 76 inch with a 38 pitch. I want a 40 or 41 pitch.
now i cruse at about 77 mph Is there a formula On pitch vrs, speed like for every Two deg of pitch you get a __ increse in speed.....
Dose anyone have a 40 or 41 inch prop what do you cruse at......
Thanks in adv.
Lance

[Hank Jarrett]

Re: Prop vrs, speed

Make sure you check with others in the tribe before you clip or re-pitch a prop. Once it is trimmed you can never go back and there is a limit to how many times you can re-pitch one (you DO keep a prop log so you know if it has been re-pitched, right?) It is a whole lot less expensive to trade with someone who needs what you have than to modify one.
Hank

I am pretty sure the FARs REQUIRE a prop log and NO, I didn't have one either, but with this knee down time I am going through the logs and making one.

[astjp2]

Re: Prop vrs, speed

Hank a prop log is not require, its restamped and you can see the difference on a fixed pitch prop. By the way, it only 8" of total change. Tim

[matsuthunder200]

Re: Prop vrs, speed

I cruse at about 2300 to 2350 rpm that gives me about 75 to 77 mph I am going to get another prop but keep this prop for floats.
I would like to get another 10 mph so i can at least keep up with a few of my buddys. I had a cruse prop and a 75 hp motor.when we first got her it crused at 115 mph but it sucked on take off I think it was a 72-52. Then i put in the 90hp and the 76-38 prop the dif was like going from a vw bug to a corvette..
Thanks for the info .

[matsuthunder200]

Re: Prop vrs, speed

Tim
Is Merill Field propeller still there i think someone told me he is gone. I havent been there in a few years.

[astjp2]

Re: Prop vrs, speed

Last I knew, he was in Eagle River. Been a few years though. Tim

[cvavon]

Re: Prop vrs, speed

just were talking about him on supper cub his phone# 688 2368 hope this helps

[matsuthunder200]

Re: Prop vrs, speed

Thanks for the number. They have new owners as of about a year ago and now they are at the birchwood airport..
Thanks Lance.

[jim cooper]

Re: Prop vrs, speed

I repitched the mccauley 90 series on my champ a few years back. (Leavens in toronto did it while I waited. Spectacular shop and equipment.) Cost was 150.00. It went from 47 to 43. BIG difference. Champ had an 85hp engine. Climbed much better and cruise was good. JC