float equiped T ....prop question

[Robert Bradbury]

I have a C90 and I'm swinging a Sen 74 39 prop at 2400 static.

I have been told by another Tcrafter that the Sen is junk and to
throw it away and get a McCauley 74 40. Is there that much of
a difference? What are the rest of you using and what is your
static, full open cruise RPM and your cruise speed?

Robert

[astjp2]

Re: float equiped T ....prop question

I know of one that is a 74ck43, on an O-200, static is 2300 or so and it tops out at 2750 @ 106kts. Tim

[Robert Bradbury]

Re: float equiped T ....prop question

I know of one that is a 74ck43, on an O-200, static is 2300 or so and it tops out at 2750 @ 106kts. Tim

Was this a McCauley clip tip prop and this was on floats? Wow! That would
be a lot of pitch even for a 0-200 especially on floats.

[astjp2]

Re: float equiped T ....prop question

No, Sensenich M74ck-0-43, not an approved combo but the prop is rated to 100HP@2650. Its on a T-craft with 8.50's and that was wide open throttle in level flight at 2500MSL in a square pattern verified by GPS. Tim

[gcgilpin]

Re: float equiped T ....prop question

The general consensus seems to be that the Sensenich 76-AK-2-40 (or 38 pitch) is the best seaplane prop.

I'm not sure how much of a difference it makes compared to a similar McCauley. Can't see it being much better.

The only way to tell is to try it on YOUR engine.

I run a 7140 McCauley on an O200 (actually a C90 because it has the 530788 cam). Static (tied down) is about 2500-2550. It'll run up to 2900 in cruise if I let it.

I'm thinking about going to a 7440 or repitching mine to 7142.

Works good for getting off on floats or skis but, once I'm in the air I always wish I could use some more of the top end power.

[T-Rex]

Re: float equiped T ....prop question

I have Edo 1320's the Model19 conversion and a c-85. What do you guys think the best sea prop would be? Right now I have a McCauley 1B90 70x46. I am contemplating overhauling and repitching or buying a longer prop.

[astjp2]

Re: float equiped T ....prop question

76-40 if you can find one. tim

[T-Rex]

Re: float equiped T ....prop question

Do you think I will get my static rpm into limits with that mutch length and only 85hp? How do you think the approved props would work, the Mac 1B90 71x42 or the Sen 74CK-2-42. Do you guys know what the difference is between the Sen AK and CK props.

[astjp2]

Re: float equiped T ....prop question

Well the Borer props are 80+ inches, if you need go flatter. Tim

[gcgilpin]

Re: float equiped T ....prop question

I have Edo 1320's the Model19 conversion and a c-85. What do you guys think the best sea prop would be? Right now I have a McCauley 1B90 70x46. I am contemplating overhauling and repitching or buying a longer prop.

If you keep the current prop...

You have too much pitch... I'd flatten it to about 42 or 40. It will make a noticeable difference. But you're going to notice a difference in cruise speed.

If your concerned about losing cruise speed try 42. If you want to optimize off the water performance on hot days with a full load go to 40. If you're not sure try 41 :-)

What's your static RPM with the 7046?

I used to run a 7140 on a C85. The flattest 71 inch 1B90 I've heard guys using is a 38 pitch.