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Cruise prop and climb prop pitch for C90-12

A

Andy Meyer

MEMBER
New owner of a PA-18-95 that has a C90-12 and came with two props. One is a Mac 71-46 cruise prop and the other is a Sen 76-2-42 climb prop. Can others with more experience then I confirm those are correct/desired pitches for each? My home strip is at 1200’ Elevation in North Central Iowa. Most of our flights will be local hops around our lake and almost always out of our 2700’ strip. At the same time we will likely be flying along with a 150hp Super Cub and a GCBC. So I’m leaning towards sticking with the cruise prop but am most curious to know if a 46 pitch is indeed a desired cruise pitch.

Thanks,
Andy
 
All because of a WTB ad I made on here a few weeks ago... 1960 PA-18-95

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I maintain a 57 and 58 factory 90hp’s. Both of those have double groove trim, higher gross weight and flap pulley mounts.


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The Sensenich 76AK-2-XX (42 seems good for a 90hp) is the benchmark for climb performance on small cont's so that's a good one to have. Spendy too so if you picked it up with your cub that's a good buy.

The Mac 7146 is definitely more towards the cruise side but is just a good all-around performer. Picks up speed over the Sensenich but doesn't give up a ton of short field/climb performance to it either. Both really good props to have on hand and both very expensive to buy new.

If you're dead set on the Mac it's a good prop but the Sensenich is widely regarded as a better performer for most things but gives up a few MPH in cruise. On that slick little 18-95 you shouldn't have any problems keeping up with a big engine cub but the Scout would probably outrun you. Or you can get used to going slow and just meeting your friends a few minutes "fashionably" late.
 
That's Purdy! I have a Sensenich 76AK-2-40 on my C90-12F Taylorcraft on floats.....It's a wonderful prop. the 42 pitch you have will be a great combo with the C90. As was mentioned here....that is the primo prop for a C90 PA18. Nice job.
 
RaisedByWolves said:
I maintain a 57 and 58 factory 90hp’s. Both of those have double groove trim, higher gross weight and flap pulley mounts.


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Click to expand...

I thought all of the 95's had the flap pulleys and double groove pulleys...? Didn't they all have a 1500# GW?
 
Try some static rpm runs, climb performance, and cruise with both and let us know the results. Lots of info on either prop but rarely on the same engine. Nice Cub!

Gary
 
J3Jim said:
Wow! Beautiful! Does it have electricity?


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Click to expand...

Yes, this one left the factory in 1960 with the C90-12F and still has the original pull type starter installed. It may be on the chopping block in the near future as I will likely be installing a light weight starter.
 
put the 76-42 on and when you go traveling the 71-46, but i doubt you will ever take the 42 off. i have a 40 and once in awhile i wish i had a 41 or 42 pitch.
 
Andy Meyer said:
Yes, this one left the factory in 1960 with the C90-12F and still has the original pull type starter installed. It may be on the chopping block in the near future as I will likely be installing a light weight starter.
Click to expand...

I'd give it a go without any starter at all and just hand propping. Small continentals are so easy to hand prop I wouldn't bother with a starter unless you have some physical limitation that precludes it.
 
Sensenich ground adjustable???
Then you can change pitch without changing prop.


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Sensenich ground adjustables for the O-200 are all experimental as far as I've heard. Plus the shorter of the two (72" I think?) had problems with causing crankcase cracks due to weird harmonic vibrations. Talked to Sensenich about them a month back or so.
 
Crash said:
Sensenich ground adjustables for the O-200 are all experimental as far as I've heard. Plus the shorter of the two (72" I think?) had problems with causing crankcase cracks due to weird harmonic vibrations. Talked to Sensenich about them a month back or so.
Click to expand...

Love mine, never could find a "good" reason not to use it. Bendix blamed some mag problems using it. But I know 2 different Legend Cubs with over 1000 hrs on it. My Ex 0200 SC on 31s would go 111mph pitched at 52 WOT level and still have decent climb

Glenn
 
I have a Sensenich adjustable on my plane. 0-235. Works great. Haven’t tried in on floats yet but it is smooth and pulls hard on take off while cruising 110.
 
Good to know. I had looked at buying one but was warned off by a few people. And yes, that's what it was- killing magnetos, not case cracks; thanks for clearing that up.
 
Wow that is the exact a/c I’m interested in. Had a J3 c90 n loved it! hand propping not for me.

What is GW EW and fuel capacity?

How do these perform compared to a J3 C90?

Thank you for feedback and congrats!


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J3Jim said:
Wow that is the exact a/c I’m interested in. Had a J3 c90 n loved it! hand propping not for me.

What is GW EW and fuel capacity?

How do these perform compared to a J3 C90?

Thank you for feedback and congrats!


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Click to expand...


Gross weight on all -95’s is 1500lbs. Empty weight on this one is in the 9’s. Still has original pull starter, generator, and heavy/rear mounted battery so a few pounds could be loss... This one has 18gals in each wing... so 36gal total.
 
J3Jim said:
Thank you. You burn about 5.5 GPH?


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I only have 4.5hrs on it and that was non-stop on my flight home with it. Our weather has been crap since getting it home so I haven’t had a chance to fuel it and see what I burned but looking at the indicators I had to have burned about 5gals/hr... I know people fly the C90 all across the board on RPM but this one seems to run smoothest at 2350... so almost that entire 4.5hrs was at 2350. Could probably have done a little better if I wanted to.
 
Crash said:
Good to know. I had looked at buying one but was warned off by a few people. And yes, that's what it was- killing magnetos, not case cracks; thanks for clearing that up.
Click to expand...

"Allegedly" only Bendix mags

Glenn
 
Last edited:
cubdriver2 said:
"Allegedly" only Bendix mags

Glenn
Click to expand...

Also only the older prop that is no longer made.
The new Sensenich 76” ground adjustable was the hot ticket on the C90 that I had. Transformed that airplane.

Pb


Transmitted from my FlightPhone on fingers...
 
Farmboy said:
Also only the older prop that is no longer made.
The new Sensenich 76” ground adjustable was the hot ticket on the C90 that I had. Transformed that airplane.

Pb


Transmitted from my FlightPhone on fingers...
Click to expand...

Mines old style, works just fine

Glenn
 
cubdriver2 said:
"Allegedly" only Bendix mags

Glenn
Click to expand...

Farmboy said:
Also only the older prop that is no longer made.
The new Sensenich 76” ground adjustable was the hot ticket on the C90 that I had. Transformed that airplane.

Pb
Click to expand...

cubdriver2 said:
Mines old style, works just fine

Glenn
Click to expand...
Glenn what type mags do you have? This is the first mention I've heard of this issue. Was it just a one time event? Was it something else (like someone mucking something up) and then blaming the mags and prop? Or was it really a resonance issue between the prop and mags? How many times have we seen a mandatory inspection/alteration of some type when the original issue was someone covering up a mistake or some type of abuse which was not normal.
 
Pete, first time I saw that prop on a plane was on Mike Harts Legend Cub up on the Ramp at Greenville Me. That was also the first time I met Mike. Maybe 15 years ago or longer. I always spent time hanging around the Sensenich booth at Kosh and was familiar with the prop from talking to them. Back then I was friendly with Ed Zerker from Sensenich and we had talked about that prop becoming legal. I asked why they didn't make it 74 or 76" and he said that 72 was the limit without having harmonic problems. I lusted for one for quite a few years. Talked to the guys at Sensenich every year and the opinion was that they pulled the prop because there were 2 planes that had mag problems, both with Bendix mags running that prop. Bendix blamed it on the prop and Sensenich got scared of the liability.
I have Slicks, and I talked to Mike who was still running that prop before I bought mine used on here.

Glenn
 
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