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Thread: Climb prop C-90

  1. #1
    RaisedByWolves's Avatar
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    Climb prop C-90

    Hey guys, we have a 7EC with a C-90-12 and a sensenich 76AK-2-48. I was wondering what is approved for a climb prop, or could we re pitch the obese have. We are only seeing 2200-2300 on takeoff


    Tom

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    Beach Bum's Avatar
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    Quote Originally Posted by TomFord View Post
    Hey guys, we have a 7EC with a C-90-12 and a sensenich 76AK-2-48. I was wondering what is approved for a climb prop, or could we re pitch the obese have. We are only seeing 2200-2300 on takeoff


    Tom
    I believe approved propellers will be listed on the airplanes type certificate or STC. We installed a C-90-8 and a metal propeller on our J3... All listed on the TC.

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    aktango58's Avatar
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    I took mine in and had the pitch re done. I think I ended up at a 43 or so.

    A good prop shop will give you a good idea where it should go if you have the existing rpm and tell them where you want it.

    Note: use a reliable tac, not the one in the dash to verify the existing rpm!
    I don't know where you've been me lad, but I see you won first Prize!

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    RaisedByWolves's Avatar
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    Quote Originally Posted by aktango58 View Post

    Note: use a reliable tac, not the one in the dash to verify the existing rpm!
    I found out today, that the tach records the RPM but doesn't record the time, and it looks like a newer tach with only 280HR

  5. #5
    RaisedByWolves's Avatar
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    I have been doing some reading, sounds like 42 pitch is about right, Can a prop shop re pitch a 48 to 42? Where can i find a "localish" prop shop in new england?

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    Not sure if this will help or not, but in a conversation with Craig Catto, he told me that his 76x36 on a c-90 @2200-2300 was outpulling the whirlwind ground adjustable even when it was set to give a static rpm of 2600. Then there are the guys that run thier o-200s up to and over 3000 rpm and swear that thats the way to go. All experimental of course...

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    aktango58's Avatar
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    Doesn't Tim have a champ?

    Maybe you could do a long term borrow to test it out....
    I don't know where you've been me lad, but I see you won first Prize!

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    I used to have a C-90-12 in a J3/PA11 configuration and ran the sensenich 76AK-2 in a 37 pitch and it was under on TO by about 25 rpm and was a real performer when light.

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    Roger Peterson's Avatar
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    I am using a 76AK2-40 on a 0-200 on floats and it is a great performer. Think 42 would be too much pitch. Great Prop.

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    skywagon8a's Avatar
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    Quote Originally Posted by TomFord View Post
    Where can i find a "localish" prop shop in new england?
    Try http://www.sensenichpropellers.com/Main.html?Home.html They are in Windham CT at the airport. You might be able to fly in, have it done and fly home.
    N1PA

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    Chuck Avon's Avatar
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    On new C85-12 on tcraft i have a McCauley 1B90 cm 74/43 static rpm 2400 t/o 2500 climb 1200 ft per min cruse at 2500 rpm 107 kt the engine has 9 hr on it now so it's still braking it in

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    cruiser's Avatar
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    According to the chart in the Univair catalog 76AK-2-46 is standard and 48 is a cruise prop. Sensenich Propeller Service in in PA has given me good service in the past, they are also in North Windham, CT. Google them. Note that this is NOT Sensenich propeller manufacturing although they would probably give good service also. Similar names, different business as I understand it. Jim

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    cruiser's Avatar
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    Tom, Sounds like it's time for an Aircraft Spruce and Univair catalog for your reading room. The Spruce catalog is a little heavy on the knees though. Good luck, Jim

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    Jon B.'s Avatar
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    Tom,

    I bought a new 76AK-2-44 from Univair for my 90hp Champ (same engine as you have). I didn't care for the performance, so took it to a prop shop and had it pitched to 42.

    The take-off and cruise both improved considerably! In fact, it went faster with that pitch than at 44.

    I don't think a shop can change it that much, though. It seems to me theycould go 4-5 inches in either direction from original.

    Jon

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    aktango58's Avatar
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    'NEW' does not mean correctly pitched
    I don't know where you've been me lad, but I see you won first Prize!

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    I run a Sensenich 76AK-2-46 on my C90-12 experimental cub. I see about 2300 to 2350 on takeoff, cannot get to redline at cruise unless in a descent, thinking 42 or 43 would be better.

    Roger, flying and fishing where it is cool, what a great deal! Too hot down here! We are heading North on Tuesday.

    Stan

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    JP's Avatar
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    42 on my C-90. Works really well.
    JP Russell--The Cub Therapist
    1947 PA-11 Cub Special
    www.bloomerrussellbeaupain.com

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    925# cub, 7440 mccauly, 2650 climb not quite 80 cruise, sets you back in the seat on takeoff. for just a little more cruise a 41 or 42 would be right in there. These cattos for exp like clint says still look cool.

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    Tom I would use the prop Roger uses.Yours may be able to be pitched down that far.Check with Douten I am pretty sure that's what he runs.You should be able to go to redline in level flight.
    I run the Mac 75-35 0n my 0-200.I cruise at 2550@93mph.I don't believe it is approved on the 90.
    I met a guy at Lockhaven with a J-3/85 who was running a new M/T composite prop.He said it was an approved prop and worked really well.

    Bill

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    Quote Originally Posted by Super11XP View Post
    Not sure if this will help or not, but in a conversation with Craig Catto, he told me that his 76x36 on a c-90 @2200-2300 was outpulling the whirlwind ground adjustable even when it was set to give a static rpm of 2600. Then there are the guys that run thier o-200s up to and over 3000 rpm and swear that thats the way to go. All experimental of course...
    Clint what are you running on your 90, I like the way you try all this stuff. doug

  21. #21
    JP's Avatar
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    Quote Originally Posted by TomFord View Post
    I have been doing some reading, sounds like 42 pitch is about right, Can a prop shop re pitch a 48 to 42? Where can i find a "localish" prop shop in new england?
    http://www.airplanepropeller.com/

    A very good shop over in CT.
    JP Russell--The Cub Therapist
    1947 PA-11 Cub Special
    www.bloomerrussellbeaupain.com

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    I am currently running a 69x41 on my c-90. I see about 2550 static and a little over 2600 on climbout. I don't think that it is really that great of a prop-not enough diameter. Craig is currently building a 76x38 for me that I am really excited about. we'll see how it works when I get it. He is really busy.

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    Did you ever get that prop? I'm interested in the results. I am looking into options for an experimental 11 with C90

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    Tom, when my buddy owned that plane I put a brand new 76AK-2-42 on it. Don't know why someone would have taken it off unless something happened to it.

  25. #25
    RaisedByWolves's Avatar
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    Climb prop C-90

    Yeah I ended up with a new 76ak-2-42 and it turns up 2500 on takeoff.

    If I was exp I would be looking at a catto. Glenn had one on his o-200 powered cub, and now has a sensenich ground adjustable that he is very happy with

  26. #26
    cubdriver2's Avatar
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    1b90 7440 Mac is hard to beat on a C90

    Glenn

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    I'm experimental so I think I'll research the Catto 78-38.... Sounds like SUPER11XP likes his. This experimental realm is fun.....so many options. I always got frustrated when doing restoration that I could not change some things that I wanted to because my other planes are certified.....like I said....this is fun

  28. #28
    cubdriver2's Avatar
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    My C85 stroker has a C90 cam, 85 pistons 8.6-1 and would not turn a catto 7636 above 2250 static. I never flew it on my J4 because it couldn't get me off the pond that my Mac 7440 does.

    Glenn

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    I have two 76AK-2-42 props and both Limit the engine to around 2350rpm on C90-8. I'd like to repitch one to 38.

    Dave

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    Quote Originally Posted by cubdriver2 View Post
    My C85 stroker has a C90 cam, 85 pistons 8.6-1 and would not turn a catto 7636 above 2250 static. I never flew it on my J4 because it couldn't get me off the pond that my Mac 7440 does.

    Glenn
    great info Glenn. It's not like you can rep itch one either....so I better do my research. I have a 76AK-2-40 on my 90 TCraft on floats and that works good.i am interested in the weight savings of the Catto

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    Quote Originally Posted by Dan Gervae View Post
    I'm experimental so I think I'll research the Catto 78-38.... Sounds like SUPER11XP likes his. This experimental realm is fun.....so many options. I always got frustrated when doing restoration that I could not change some things that I wanted to because my other planes are certified.....like I said....this is fun
    yep 78x38 is a great prop. I had c85 pistons and Vetterman exhaust on my plane. 38 pitch might be a bit course without those 2 things. The experimental thing certainly is fun!!

  32. #32
    cubdriver2's Avatar
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    ReliableFlyer on here has a Catto 7834 on his C90 cub, maybe he will comment on how its working. I loved the Catto while I was using it on my 0200 cub. Even though static was only 2350 it still pulled great. You can feel the weight difference as soon as your airborne.

    Glenn

  33. #33
    Ken Kennedy's Avatar
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    I heard of a guy that put a 80-30 Catto on his C85 stroker and apparently it is a hell of a performer. I heard to turns about 2350 static, and about 2600 in a 45 mph climb. Guy said it was a night and day difference between the 76AK-2-42 that it replaced; over 100 lbs harder pull on the same day which was supposedly around 5K density altitude.

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    Catto recommended the 76-36 for my stock O200A on my PA11EX I hope it is the ticket....I ordered one. If I can't get the static I want maybe I'll go with Lycon high compression Pistons.....was hoping to keep it stock for now. I've got lots of building to do yet but I pick up the big items as I can afford them��

  35. #35
    mvivion's Avatar
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    This thread has gone for 34 posts, with some incriminating evidence posted by those who are operating certificated airplanes--maybe.

    Here is what the 7EC type certificate says about propellers and propeller RPM:

    Engine Limits For all operations, 2475 r.p.m. (90 hp.)
    Airspeed Limits Level flight or climb 100 m.p.h. ( 87 knots) True Ind. Glide or dive 135 m.p.h. (117 knots) True Ind.

    Propeller Limits Static rpm at maximum permissible throttle setting: (For fixed pitch Not over 2350, not under 2125. No additional tolerance permitted. wood propeller)

    Diameter: not over 72 in., not under 70 in.

    So, if your current propeller pulls between 2125 and 2350 STATIC (as in full throttle, on the ground, NOT moving) then it is within legal limits. Repitch it to get better climb or cruise, and if it then runs static outside those limits, it is not legal.

    And, for those folks advertising on the world wide web that their C-90s on certified aircraft are running 2600 rpm.....note that the Continental TCDS (and the above 7EC TCDS) says Maximum rpm for the Continental C-90 is 2475 RPM for ALL operations.

    If you're experimental, obviously, you can do whatever you want with your engine.

    But, for the OP, these are the limits for your engine. 2200 to 2300 for takeoff is probably pretty close to that static limits noted above.

    Also, a review of the TC for your airplane will also tell you what propellers are approved for the plane. The TC is the first place you should go for basic information like this....THEN troll the internet.

    MTV





    Engine Limits

  36. #36
    C-FIJK's Avatar
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    What RPM are you getting Roger ?


    Quote Originally Posted by Roger Peterson View Post
    I am using a 76AK2-40 on a 0-200 on floats and it is a great performer. Think 42 would be too much pitch. Great Prop.

  37. #37
    cubdriver2's Avatar
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    Quote Originally Posted by mvivion View Post
    This thread has gone for 34 posts, with some incriminating evidence posted by those who are operating certificated airplanes--maybe.

    Here is what the 7EC type certificate says about propellers and propeller RPM:

    Engine Limits For all operations, 2475 r.p.m. (90 hp.)
    Airspeed Limits Level flight or climb 100 m.p.h. ( 87 knots) True Ind. Glide or dive 135 m.p.h. (117 knots) True Ind.

    Propeller Limits Static rpm at maximum permissible throttle setting: (For fixed pitch Not over 2350, not under 2125. No additional tolerance permitted. wood propeller)

    Diameter: not over 72 in., not under 70 in.

    So, if your current propeller pulls between 2125 and 2350 STATIC (as in full throttle, on the ground, NOT moving) then it is within legal limits. Repitch it to get better climb or cruise, and if it then runs static outside those limits, it is not legal.

    And, for those folks advertising on the world wide web that their C-90s on certified aircraft are running 2600 rpm.....note that the Continental TCDS (and the above 7EC TCDS) says Maximum rpm for the Continental C-90 is 2475 RPM for ALL operations.

    If you're experimental, obviously, you can do whatever you want with your engine.

    But, for the OP, these are the limits for your engine. 2200 to 2300 for takeoff is probably pretty close to that static limits noted above.

    Also, a review of the TC for your airplane will also tell you what propellers are approved for the plane. The TC is the first place you should go for basic information like this....THEN troll the internet.

    MTV





    Engine Limits
    Do what cub crafters does, placard by throttle " limit take off power to 2350 RPM "

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  38. #38
    cubdriver2's Avatar
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    Quote Originally Posted by Dan Gervae View Post
    Catto recommended the 76-36 for my stock O200A on my PA11EX I hope it is the ticket....I ordered one. If I can't get the static I want maybe I'll go with Lycon high compression Pistons.....was hoping to keep it stock for now. I've got lots of building to do yet but I pick up the big items as I can afford them��
    I had that prop on my 0200A and would go to a 7634 if you want to stay stock. YMMV

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  39. #39
    mvivion's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    Do what cub crafters does, placard by throttle " limit take off power to 2350 RPM "

    Glenn
    Different ball game entirely. First, not a "certificates" airplane...LSA. Second, the engines in those airplane's are rated by the engine manufacturer for 2700 continuous rpm. The limitation there has to do with meeting LSA standards.

    In this case, the Continental C 90 is very specifically limited by the manufacturer. You don't get to meet the static rpm limit via a placard, as far as I know.

    Violate these limits at your own peril. Advertise same in a public forum, however, is rather ignorant.

    FWIW.

    MTV

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    I agree. Telling the world you're breaking the regs is only slightly less questionable than the folks who post videos of their flights that clearly show they are violating cloud clearance or other FAA rules, while advertising their names and N-numbers and even showing the pilot's face... Talk about making the FAA regulator's life easy! As a buddy of mine says "Everyone steps on their d*** once in a while. The trick is not to be wearing golf cleats when you do!"

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