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Thread: Catto 84/42 vs 86/38 Pull Test Results

  1. #1
    tcraft128's Avatar
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    Catto 84/42 vs 86/38 Pull Test Results

    12.19.2014, using a 1000lb dynamometer, we pull tested our two Catto Props. The engine was at operating temperature for all of the runs. Using "Chester", our E250 work van/crew car, as an anchor, a fall arrest sling and a 1" rope tied to the receiver hitch we gathered the follow data.

    Pull Set A

    Weather at first pull, approx 1pm local, Temp 51*F, Dew Point 46*F, 30.11, 82% Humidity, 5mph headwind.

    This is a GEN 1 Catto Prop without the Nickel leading edge installed. (Catto cannot add nickel to this series props FYI)

    Here is the tag for the first prop.



    The three attempts are as follows: Pull attempt/Thrust (lb)/RPM

    1. 700 2340
    2. 705 2340
    3. 700 2335




    Pull Set B

    Weather at 2nd pull, approx 2pm local, Temp 50*F, Dew Point 45*F, 30.11, 82% Humidity, 5mph headwind.

    This is a GEN 2 Catto Prop with the Nickel leading edge installed.

    Here is the tag for the 2nd prop. (currently installed)



    The three attempts are as follows: Pull attempt/Thrust (lb)/RPM

    1. 780 2280
    2. 780 2280
    3. 775 2280



    Pull Set C

    Taylorcraft L-2B
    C-85

    350lbs


    Conclusion

    We are going to stick with the 86/38. After we reinstalled the spinner and flew the airplane, Dad reported that he could tell something had changed for the better. From the ground, the airplane sound has changed to mimic a 185. This was a really fun day at St. Marys Aviation, Bill Hayes and Nick Cope helped out.

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  2. #2
    skywagon8a's Avatar
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    Good information. Just one question. What was the difference in cruise or top speeds at the same rpm?
    N1PA

  3. #3
    tcraft128's Avatar
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    I don't have that yet, the weather has gone bad and I have not finished that part of the testing. I will post but most likely after christmas.
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    It would be cool now to see what a 8440 would do, would like to see if it has the pull of a 38 but a little cruise might be gained? Great Info.

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    Olibuilt's Avatar
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    Quote Originally Posted by tempdoug View Post
    It would be cool now to see what a 8440 would do, would like to see if it has the pull of a 38 but a little cruise might be gained? Great Info.
    Yes! And a 8640 too... Maybe Cub12 could do that test??

  6. #6

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    Yep, from a 84 inch to 86 inch, is there any change? I see the rpms are down 60 with the longer prop.

  7. #7
    DW's Avatar
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    Was the engine a stock 0-360 those static numbers on the 86/38 look pretty low....a stock 0-360 should see 2375 static with that prop and pull in the 870 range

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    But its still the same engine.

  9. #9
    DW's Avatar
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    As a general rule on Catto props for every 1" of pitch change you will see 50 rpm this will of course very some from engine to engine as no two are exactly the same.

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    So how about each 1 inch of prop length? How will that vary the pull and the rpms? On the same engine.

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    on my cub going from the 86/40 to the 38 i lost 8-10mph on skis, a friend of mine has the 40 on his 18, i will see if i can borrow it back for a pull test this spring if no one else gets it done before me.
    Merry Christmas to everyone Marc

  12. #12
    DW's Avatar
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    Again this will very from engine to engine but for every 1" in blade or 2"s diameter you are going to see about a 70 rpm difference so as you increase the diameter you will want to start decreasing the pitch..........and as you probably know most of the tach's out there are off so you will need to get that checked first to get some good accurate numbers.

  13. #13
    tcraft128's Avatar
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    I have just ordered a digital tach tester.

    I cant imagine that my engine is weak, the airplane will land, stop and depart on a runway stripe, 120'. I trust what you are saying DW, I guess I will start to troubleshoot. I have not flown the new prop, Dad has and he says that it is a very noticeable improvement. ??

    DW, are you using a mechanical tach or pulling a signal off the PMAG? I am digital.

    I also put a call in to Catto. I am going to check the timing on the engine tomorrow.

    Engine Specs. Just did an oil change and the compressions are fine, heck it has 58 hours on it.

    o-360 narrow
    9.5:1
    Aero performance stage 3 cam
    flowed cylinders
    equal length exhaust 4-1 merge collector
    Dual electronic PMAG ignition

    Great, now I am worried about my airplane......
    Last edited by tcraft128; 12-22-2014 at 05:00 PM.
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    If some way you can get a 8440 and an 8640 to test, send me the bill for renting the gauge.
    Last edited by tempdoug; 12-22-2014 at 06:15 PM.

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    tcraft128's Avatar
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    I need to solve the problem that I have with the static RPM being low, I really am starting to question the timing, if it is retarded at the start point during the initial setup, then that could be robbing power. DW what is your Static Fuel Flow?

    What is anyone's static fuel flow o-360?
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    Olibuilt's Avatar
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    Stock O-360 C4P, Sutton exhaust, standard mags, mogas, hobbyzone digital tach, on floats, white cub... about 2350rpm on initial engine rev, with a 86-38 Catto. Didnt want to tie me to a dock... But the performance were much better than a McCauley 8242 climb prop. Lost less than 5mph (90-95mph).

    Will do a static test on the RedDevil soon with the same prop, no pull test, in really cold air, to order a new prop.

  17. #17
    DW's Avatar
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    Can you pull it again and see if you maybe misread and it's turning 2380 not 2280 because that would sound about right.

    After going back and looking at your numbers I don't think you misread them because if it was turning 2380 you should be pulling in the mid 800s

    sounding more like timing....I have a mechanical tack that has been digitally calibrated no fuel flow and I use a digital crane scale.
    Last edited by DW; 12-24-2014 at 02:21 AM.

  18. #18
    tcraft128's Avatar
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    Update: After the warm fuzzy feeling of pulling 780lbs subsided and we came to the realization that what we were seeing on the scale and tach were not quite what we should be given our engine prop combination, Dad and I decided to take off the cowl, tie to bird to the Van again and start troubleshooting. During all the operations, I was outside watching the engine make noise and recording results and Dad was operating the engine.

    First, we verified our digital tach to a model airplane tach checker that I bought on amazon for 15 bucks; it was spot on at 1000 and 2000 and showed 2290 as our initial max static RPM.

    The second item that we looked at were the Pmags. We have 2. After the timing was verified to be set at 1 ATDC (version 34 firmware) we discussed with Brad from Emag some of our options. (side note: Brad answered the phone the day after Christmas and took the time to help out with our problem) We are right now running the standard timing curve (jumper in) with the startup at 1* after TDC. With the jumper in and the manifold reference tube connected, we should be seeing advances of 31* BTDC at full power. If we remove the jumper, we will shift the curve to a 35* BTDC curve. We tried the jumper out and actually lost power. Ok, something is not right here. One of the variables that we introduced was leaning. During the runs, leaning the mixture almost an inch produced increased RPM on the tach. I can hook a laptop to our ignition system and adjust on the fly the timing curves, which after I procure my own scale, I will use this to tune the ignition to our aircraft. Stay tuned.

    After we were sure that the mags were not an issue, we went to the carb. We were lead here because of the fact that leaning would increase the RPM. We pulled the 10-5193 MA4-5 carburetor apart and checked the main jet (still a standard size 47-830, o360 jet), float height (13/64"), and for any FOD or gunk. There was a small leak around the base gasket to the venturi, evident from carbon deposits on the gasket, but really nothing out of the ordinary for an old tractor carb. We did clean the jets, needle and replace the leaking gasket. After all the tweaking and cleaning, when leaned, we will now consistently see 2380 RPM static. Full rich produces 2350 static.

    The last piece of the puzzle is the airbox. We are going to make a composite plenum similar to whats on an RV hoping that the little airbox that we found in the attic shelf in the shop and modified to fit the front of the cub cowl is just to small and causing the bottle neck on our motor. I am convinced (hoping) that this is the case because everything that we have read, we should have to drill the main jet and our engine should be running lean, well its not, there is plenty of gas available on the stock main jet, so much that we at full power, leaning provides an increase in power. So, did we find a smoking gun, no, but something changed and we now see 2350-2380 RPM static.

    With all this being said, our airplane is still a rocketship and we could not be happier with the performance.

    Also, I am looking around for a scale like we used to pull test the airplane. When I find one, I would like to pass it around and see what everyone else is doing for static poundage and compile a database for future reference.

    -Jay
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  19. #19
    Olibuilt's Avatar
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    I would do a pull test with my stock O-360C4P and 8638 Catto.

    Thanks for all the info. I will try to pull the mixture on the next static test, just to see.

  20. #20
    tcraft128's Avatar
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    Click image for larger version. 

Name:	20150625_154403.jpg 
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    Guess who got a new catto prop....
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  21. #21
    skywagon8a's Avatar
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    Someone has a story to tell.
    N1PA

  22. #22
    RaisedByWolves's Avatar
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    Hey look, it's a wood prop.

  23. #23
    Olibuilt's Avatar
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    You could have cut it cleaner if you wanted a cruise prop..


    Seriously, what is going on?

  24. #24
    mike mcs repair's Avatar
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    Quote Originally Posted by tcraft128 View Post
    Click image for larger version. 

Name:	20150625_154403.jpg 
Views:	281 
Size:	914.8 KB 
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    Guess who got a new catto prop....
    "..and, it's performance in the roto-tiler demonstration was...'

  25. #25
    Wag2+2's Avatar
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    Student mishap?

  26. #26
    tcraft128's Avatar
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    Student mishap is correct. Story tomorrow with new data. On new 86x36.

    Jay
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  27. #27

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    No good. Makes me a little sick to my stomach and its not even my rig. Get it back together.

    Hang in there.

    Jim

  28. #28
    tcraft128's Avatar
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    The week before New Holstein, Dad was giving a demo of the cub to a recent tailwheel student and allowed the guy to sit in the front seat. The instructions were to give it some power and raise the tail. That is exactly what the student did, only the tail went far enough to put the prop into the runway. This resulted in the removal of 25” per blade off the prop. Dad reported that the engine did not slow down at all and the prop felt like foam getting hit with a belt sander. Thanks to Dads cat like reflexes, the power was managed along with near instant full stick back, and the plane suffered no harm. So I called Catto, told Nicole our story and ordered another Catto Prop
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  29. #29
    tcraft128's Avatar
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    Pull Testing continued…

    Currently in the barn, versions of the Catto 86x36 propeller for the 0-360 engine. The First version has a significant cup on the aft surface of the propeller caused by the manufacturing process used to fit and adhere the nickel leading edge onto it. Cupping a propeller will increase the realized pitch of the propeller without changing the actual pitch. This is used in motorboat props to fine tune pitch changes and has other benefits like cavitation resistance. The other 86x36 is the prop that I picked up at Oshkosh from Nicole Catto. It is the newest profile and is virtually flat on the aft surface. The differences between the 2 props was almost 100rpm static, from 2360 to 2440, however, the thrust did not change. I went back and looked at the other pull data that I have collected, and initially was shocked to see that the 86x38 pulled almost 780lb! But these tests are not apples to apples. Density altitude was playing with my data. The two factors that I chose to correct for were horsepower and thrust. I used some online calculators for HP corrected for altitude and a calculator for D.A. Using this information, I came up with a correction factor that I plugged in to standardize the thrust variables.

    Click image for larger version. 

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    I will be soon receiving a 90x26 Mccauley propeller to pull test. I will post the data in this corrected format.

    Just a little disclaimer, the weather information was taken from NOAA at the time of the test as our airport does not have any weather reporting available.

    Cruise Data

    Some of you have asked me about changes in cruise speed. Here is a list of the data we collected during our trip to New Holstein. The cruise prop that I reference is a Sensenich 76-60 off a Beech Musketeer, 76EM8S5-0-60. This prop has a 1” spacer pressed on at the factory. This allows us to use the same prop bolts as the Saber extension that we use to mount the Catto props. We also had the seamstress make a bag to protect the Catto prop while it is in the baggage compartment. So, we will be arriving just outside of Johnson Creek with our Metal Prop, the switching to the Catto to play!

    76-60

    100mph IAS @ 2330 RPM
    Oil Temp 197*F
    Oil Psi 78
    1325 EGT / 390 CHT
    8.7GPH
    11.49 MPG

    86x36
    85mph IAS @ 2450
    Oil Temp 208*F
    Oil Psi 75
    1320 EGT / 375 CHT
    7.9GPH
    10.75 MPG

    Like Bill says, Hope this helps!
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  30. #30
    Mauleguy's Avatar
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    I did a pull test with my 90/33 years ago, it was a 50 degree day at sea level. I did 3 pulls and the average was 905 the static rpm was 2440 with a digital tach. My engine had a fresh top end (2100 on the bottom end) with 10.5/1 pistons and a homebuilt exhaust that should have helped. I flew that same propeller for almost 10 years until I wrecked it last year at that time the engine had 3900 SMOH on the lower end.

  31. #31
    D.A.'s Avatar
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    Quote Originally Posted by tcraft128 View Post
    …The First version has a significant cup on the aft surface...
    I just got an email from Craig saying he’s going to make another 86X36 for us with the revised CNC file that you have. Good guy that Craig.
    Quote Originally Posted by tcraft128 View Post
    …I will be soon receiving a 90x26 Mccauley propeller to pull test…
    DOH! To tell you the truth, once I found that crack, I forgot about everything else including shipping that prop to you. I’ll get that done this week.
    Quote Originally Posted by Mauleguy View Post
    I did a pull test with my 90/33 years ago…
    Greg, was that a 1A200 also?

  32. #32
    Chris in Idaho's Avatar
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    Hi Jay,
    Thanks for posting all of this great info. Do you happen to have any cruise data from your 86x38 before the student mishap?

    Quote Originally Posted by tcraft128 View Post
    Cruise Data

    Some of you have asked me about changes in cruise speed. Here is a list of the data we collected during our trip to New Holstein. The cruise prop that I reference is a Sensenich 76-60 off a Beech Musketeer, 76EM8S5-0-60. This prop has a 1” spacer pressed on at the factory. This allows us to use the same prop bolts as the Saber extension that we use to mount the Catto props. We also had the seamstress make a bag to protect the Catto prop while it is in the baggage compartment. So, we will be arriving just outside of Johnson Creek with our Metal Prop, the switching to the Catto to play!

    76-60

    100mph IAS @ 2330 RPM
    Oil Temp 197*F
    Oil Psi 78
    1325 EGT / 390 CHT
    8.7GPH
    11.49 MPG

    86x36
    85mph IAS @ 2450
    Oil Temp 208*F
    Oil Psi 75
    1320 EGT / 375 CHT
    7.9GPH
    10.75 MPG

    Like Bill says, Hope this helps!

  33. #33
    Mauleguy's Avatar
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    Yes

  34. #34
    tcraft128's Avatar
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    Chris, I dont have as detailed cruise info on the 86x38, but it was around 95mph IAS at the same power setting as the 86x36 shown above.
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  35. #35
    D.A.'s Avatar
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    Quote Originally Posted by tcraft128 View Post
    ...cruise info on the 86x38...was around 95mph IAS at the same power setting as the 86x36 shown above.
    When it comes to Math, there's 3 types of people, those that understand it and those that don't, so my calculations might be off here, but your 36, my 36 and your 38 were all within about 13 pounds of each other which is a range of about 1.7% but the 86X38 cruised about 10mph faster which is 11.7% faster with almost no static pull penalty. Unless I'm missing something here Jay, the flatter pitched Cattos don't pull significantly harder, they just fly slower, is that what you're seeing?

  36. #36

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    Would like a little more our r. p.m. Can a Catto propeller be shortened by a few inches? Yea I know, but not with an axe.

  37. #37
    Chris in Idaho's Avatar
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    Quote Originally Posted by tcraft128 View Post
    Chris, I dont have as detailed cruise info on the 86x38, but it was around 95mph IAS at the same power setting as the 86x36 shown above.
    Thanks for the info.

    Quote Originally Posted by D.A. View Post
    Unless I'm missing something here Jay, the flatter pitched Cattos don't pull significantly harder, they just fly slower, is that what you're seeing?

    That's what it looks like to me too.

  38. #38
    tcraft128's Avatar
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    I am not sure that there is an easy way to answer that question and I dont have any numbers. I do have a semi calibrated butt, so here goes some speculation. The 86x36 that I have on my plane right now, the newest version, has a higher static rpm with the same static thrust as the old 86x36 at a lower static rpm. However, the NEW 86x36 does seem to accelerate on the ground after brake release noticeably faster/harder than the old version and reaches rotation faster.

    So here is the test I am going to run. (after my planes annual is done)
    1. old prop, trim neutral, stick back, full fuel, full flaps. 10 Take off measurements from a line.
    2. Switch props quickly. usually about 5-8 min.
    3. New Prop, trim neutral, stick back, full fuel, full flaps same pilot. 10 Take off measurements from a line.

    What will this show? It will show what prop is best for take off performance, non laboratory.
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  39. #39
    Chris in Idaho's Avatar
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    That sounds perfect, Jay. Thanks for going through all of this effort. I'm very interested to see the results of this test.

  40. #40
    CamTom12's Avatar
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    Quote Originally Posted by tcraft128 View Post
    I am not sure that there is an easy way to answer that question and I dont have any numbers. I do have a semi calibrated butt, so here goes some speculation. The 86x36 that I have on my plane right now, the newest version, has a higher static rpm with the same static thrust as the old 86x36 at a lower static rpm. However, the NEW 86x36 does seem to accelerate on the ground after brake release noticeably faster/harder than the old version and reaches rotation faster.

    So here is the test I am going to run. (after my planes annual is done)
    1. old prop, trim neutral, stick back, full fuel, full flaps. 10 Take off measurements from a line.
    2. Switch props quickly. usually about 5-8 min.
    3. New Prop, trim neutral, stick back, full fuel, full flaps same pilot. 10 Take off measurements from a line.

    What will this show? It will show what prop is best for take off performance, non laboratory.
    While you're swapping props, you should get some cruise speeds at various RPMs with each as well. That would be interesting to see. The NEW one is the prop that does not have the cup on the back of the blade, correct?

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