Cruise prop and climb prop pitch for C90-12

[Andy Meyer]

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

[Utah-Jay]

We here at SuperCub.org like airplane porn, so let’s see it

[Andy Meyer]

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

[Utah-Jay]

Beautiful bird

[1934A]

Glad you found a good one!
Anybody know when Piper quit building the 95hp Super Cubs?

[RaisedByWolves]

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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[Crash, Jr.]

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.

[bob turner]

You lucky guy!

[iancallier]

Very nice, AND a clean drip tray - ENVY!

[Dan Gervae]

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.

[1934A]

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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I thought all of the 95's had the flap pulleys and double groove pulleys...? Didn't they all have a 1500# GW?

[J3Jim]

Wow! Beautiful! Does it have electricity?


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[BC12D-4-85]

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

[Andy Meyer]

Wow! Beautiful! Does it have electricity?


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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.

[tempdoug]

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.

[Crash, Jr.]

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.

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.

[Doug Budd]

Sensenich ground adjustable???
Then you can change pitch without changing prop.


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[Crash, Jr.]

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.

[cubdriver2]

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.

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

[TcraftF21]

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.

[Crash, Jr.]

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.

[J3Jim]

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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[Andy Meyer]

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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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]

Thank you. You burn about 5.5 GPH?


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[Andy Meyer]

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.

[cubdriver2]

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.

"Allegedly" only Bendix mags

Glenn

[Farmboy]

"Allegedly" only Bendix mags

Glenn

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...

[cubdriver2]

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...

Mines old style, works just fine

Glenn

[skywagon8a]

"Allegedly" only Bendix mags

Glenn

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

Mines old style, works just fine

Glenn

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.

[cubdriver2]

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

[mam90]

SENSENICH PROPELLERS 2008 WOOD COURT PLANT CITY, FL 33563 PHONE –(813)752-3711 FAX – (813)752-2818 14 CITATION LANE LITITZ, PA 17543 PHONE –(717)569-0435 FAX – (717)560-3725 NOTIFICATION NO. CN-1-13 Sept 27, 2013 TO: ALL AIRCRAFT OWNERS AND OPERATORS USING CONTINENTAL O-200 ENGINES AND SENSENICH C72AE PROPELLERS SUBJECT: MAGNETO FAILURES / PROPELLER HARMONICS PROPELLER MODEL(S): SENSENICH 2EK/C72AE, 2EL/C72AE GROUND ADJUSTABLE COMPOSITE PROPELLERS AIRCRAFT MODEL(S) AFFECTED: ALL AIRCRAFT USING CONTINETAL O-200 ENGINES AND SENSENICH C72AE PROPELLERS DISCUSSION: Sensenich has been made aware of random magneto failures on Continental Motors Inc (CMI) O-200 series engines that CMI has attributed to operation with the Sensenich composite C72AE propeller. These failures appear to be intermittent and CMI reports that the magneto failures are a result of a 6th order vibration that CMI attributes to a vibrational resonance of the engine/propeller combination. While the Sensenich composite propeller is not experiencing any problems related to the resonance referred to by CMI we do acknowledge that the propeller and engine are not mutually exclusive and must ultimately be considered as a system. It is unclear at this time if these issues affect all composite propellers used on CMI four cylinder engines or if it is specific to one particular manufacturer’s propeller model. Sensenich has traditionally approved propellers for use on aircraft engines based on a vibration survey of the propeller and endurance testing per 14 CFR part 35 or ASTM F2506. Vibration surveys record what is happening in the propeller as a result of operation on a particular engine and this data is then used to determine the airworthiness of the propeller on that particular engine configuration. All propeller/engine combinations exhibit vibrational harmonic interaction. It is not possible to design a propeller that will not exhibit vibrational harmonics within the operating envelope when run on an internal combustion engine. The Sensenich C72AE propeller has been vibration tested in accordance with ASTM F2506 and has been determined airworthy for use on the CMI O-200 series engines. Sensenich has not historically determined the airworthiness of the entire propeller, engine, airframe combination but has provided data, typically to the airframe manufacturers, in support of those efforts. As a result of these magneto failures CMI is requesting that Sensenich discontinue recommending and selling composite propellers for use on CMI four cylinder engines. Although the vibration survey has demonstrated the C72AE propeller to be airworthy when operated on the CMI O-200 series engines and there are numerous installations that have successfully logged in excess of 300 hours without magneto failure, it cannot be shown with certainty that the C72AE propeller is not causing the issues with the CMI magnetos. For these reasons and in the interest of aviation safety, Sensenich has decided to temporarily suspend sales of the C72 series propeller. If at a later date the CMI O-200 series engines can be proven compatible with the C72AE propeller then sales of the C72AE propeller will continue. ADDITIONAL INFORMATION: Sensenich is currently in the testing phase of an additional composite propeller, the C76, designed for use on the CMI O-200 engine. The C76 propeller has exhibited significantly different vibratory characteristics from the C72AE propeller and the vibration survey of this propeller on a CMI O-200 engine is scheduled to be completed by early October of this year. Pending successful completion of the vibration survey and related endurance testing per ASTM 2506, Sensenich will release the propeller for service. Although Sensenich designs propellers for aircraft engines and airframes based on horsepower, rpm, and aircraft speed, the suitability for any particular propeller for an application is the responsibility of the aircraft manufacturer or aircraft owner. If you have any questions related to the information disclosed in this letter or to discuss any propeller options available for your application during this time please contact Sensenich directly.

[skywagon8a]

It would be interesting to learn the nature of the particular magneto failures. What exactly failed? A wire break? Or something more serious? Sometimes just repositioning some little thing makes a difference.

[TcraftF21]

Mine is the new style adjustable. I had the old style and for some strange reason it caused high cylinder head temps. Sensenich took it back. Now the new style is great. I have a76AK42 that I use on floats that maybe for sale this summer if the adjustable works good on the water. I do have about 6 different keys for the old style if some one (Glenn) wants them. Free for the asking. Oh yes, my plane has an 0-235 LYC and Slick mags.

Jim

[cubdriver2]

Jim if you have a 50 I'd like to try it. I ran a 52 pitch for the last 2 + years but now have the 48 in for skis. They make keys from 32" to 60" in 2" increments

Glenn

[TcraftF21]

I will look over the weekend and will pm you if I have. You can have them all and go crazy

[mam90]

Spoke with Sensenich yesterday to get it straight from them. They assure me a certified ground adjustable for the small Continentals is in the works and hopefully it will happen next year. Won’t hold my breath on the timing, but will keep my fingers crossed....

[Farmboy]

Spoke with Sensenich yesterday to get it straight from them. They assure me a certified ground adjustable for the small Continentals is in the works and hopefully it will happen next year. Won’t hold my breath on the timing, but will keep my fingers crossed....

Bear in mind they have a 118 experimental blades to build, 130 pre orders for O-320’s they can’t build until certified, and 140(?) for O-360’s. To say aviation exploded last year is an understatement.

Plan ahead.


Transmitted from my FlightPhone on fingers…

[mam90]

Bear in mind they have a 118 experimental blades to build, 130 pre orders for O-320’s they can’t build until certified, and 140(?) for O-360’s. To say aviation exploded last year is an understatement.

Plan ahead.

Transmitted from my FlightPhone on fingers…

Yep...... I suggested they work through their lunch hour.....