Hercules propeller

Discussion in 'Pitts Miscellaneous' started by Jean-luc, Apr 27, 2018.

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  1. Apr 27, 2018 #1

    Jean-luc

    Jean-luc

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  2. Apr 27, 2018 #2

    cwilliamrose

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    Last edited: Apr 27, 2018
  3. Apr 28, 2018 #3

    Eric_Anderson

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    I have one in storage after just a few hours of flight. You are welcome to pm me with questions but please read the thread above first.
     
  4. Apr 29, 2018 #4

    Lotahp1

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    I keep wanting to have them build me a Prop for the Ranger. I might still. They just have a fantastic look. And seems performance is as good or better than a wood Sensenich. From what I’ve been told the long waits etc have been solved.
     
  5. Apr 29, 2018 #5

    Jean-luc

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    Bill,Thank you for the thread.Very helpfull.
    Eric,i am not ready to buy a prop now.But,it seems that don't like the Hercules so much,as you have only a few hours of flight with it.
    I wish,if possible,to buy a fixed prop,here in Europe.Much lower shipping's cost and easier for maintenance if necessary.
    MT.But i know nothing about their props on a Pitts.Anyway,i do not know if they do aerobatic fixed props.
    GT.They have one installed on a Pitts S1,but no report about the performances.Cost + shipping will be as a Catto from the US,or a little bit higher.They are eavier than a Catto.
    Hercules.Not so much experience with the Pitts..But i love the classic planform with varnish...Just Awesome !!!Lauren and you Eric have the symmetrical planform
     
  6. Apr 30, 2018 #6

    Eric_Anderson

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    Jean-luc,

    You should at least talk to Rupert if you haven't already. The prop is a work of ark that needs to be seen to be appreciated. The only reason that I took it off my plane was that it felt slightly over-pitched for my engine. Hercules, at no cost to me, repitched the prop and paid for shipping in both directions! Read that again. After the rework, it still felt a little weak in the vertical, fast in cruise and had a touch of vibration--needs balancing I would guess. The new engine seems to produce a few more horsepower and might better handle the prop. But I am in no mood to fall down the rabbit hole of further testing. I just want to fly now.
     
    Last edited: Apr 30, 2018
  7. Apr 30, 2018 #7

    Jean-luc

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    Thank you Eric,I am going to follow your advice.I will contact Rupert very soon.
    If i remenber,Lauren's prop was not a pure aerobatic,as she wanted some good cruse as well.I want a pure aerobatic.I have a question for you,what is your spinner diameter?
     
  8. May 1, 2018 #8

    Eric_Anderson

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    I will find out today. One of the reasons I picked the Herc was that I could use all of the Sensenich hardware including bolts, bulkhead and spinner. I do know that my spinner is off a Grumman Tiger. When Lauren was here she quoted 2000 fpm climb at 95 mph which is exactly what I get when timed to 2000 feet AGL. I requested an identical prop to hers and I think that's what I got. The metal prop is maybe 5 seconds faster in the climb. Where I (Danny Bond actually) think the metal prop has an advantage is in rotational inertia. That positive feature was more noticeable to me in a vertical cap off than the negative torque that comes with a heavy prop.
     
    Last edited: May 1, 2018
  9. May 1, 2018 #9

    Jean-luc

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    Eric
    I just follow your advice,and sent a message to Rupert.
    I ask for a pure aerobatic propeller with the classic planform.
     
  10. May 3, 2018 #10

    Eric_Anderson

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    Jean-luc, my spinner diameter is 13.61 inches.
     
  11. May 3, 2018 #11

    Jean-luc

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    Thank you Eric
     
  12. May 10, 2018 #12

    Jean-luc

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    Eric
    I have received an answer from Rupert.
    It is possible to use the classic planform to make an aerobatic propeller.He told me that their propeller allow to achieve 2800 rpm at full throttle (max cruise).
    He suggest me to talk with experienced Pitts pilots like you and Lauren,to help decide what rpm and speed i want to see at max cruise,etc.I know that your and Lauren propeller is a compromise aerobatic/cruise.My choice will be more a pure aerobatic,as i won't travel a lot with the Pitts.My goal for the engine will be to have around 200 to 220 hp with as much torque i can get.
    I sent a message to Lauren,and hope to get an answer.
    What could be your advices
    Jean-luc
     
  13. May 10, 2018 #13

    grassroots

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    IMO to get the full performance potential of an S-1, you'll want to see at least 3000 RPM full throttle level flight. Are you saying their prop is limited to 2800 RPM? It also depends on your flying style. If you just fly for fun doing loops and rolls, then it really doesn't matter. Even flying a Pitts at Intermediate IAC level, these issues aren't too critical.

    As far as "cruise" performance goes, many folks tend to look only at the speed/RPM relationship, neglecting fuel burn. They will put on a higher pitched prop and say they gained X mph in cruise at 2500 (or whatever) RPM, but not measure the increased fuel burn. For example, I tested a 56 and 54 Catto on my S-1S, and it cruised at the same speed for a given fuel flow, but the 56 simply turned 100 RPM less than the 54. So to me there was no cruise advantage of the 56 unless I planned on flying cross country at high altitudes at full throttle, which I never did anyway.
     
    Last edited: May 10, 2018
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  14. May 10, 2018 #14

    TFF1

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    Remember one thing if your engine makes 200 hp at 2700rpm, it has to spin that fast to make 200hp. If the prop only goes to 2600, the engine is lugged to 180-190ish HP. is that bad or good? Up to you. If you want to use all the HP, you will be 3-4 inches in pitch flatter than probably any prop they recommend. What is the energy management of your maneuvers? Are you only going to lug the engine for speed or are you going to account for dives. If you want 200 hp/RPM in a climb you will probably need 2800-2900 level. Do you want the RPM to hit 2700-2900 in a dive? You will have to set the balance point of performance where it is good for you. How it will feel is going to be about you. Personally I would buy a conservative prop. It will be a much more sellable once you figure out what the airplane really needs. Get some extreme fine pitch prop and you don't like it, no one else will want it. Good for a wall hanging.
     
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  15. May 10, 2018 #15

    jrs14855

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    From the very first Curtis built S1S the standard prop for the 180 hp engine was the Sensenich 76 dia 56 pitch. Many years later as aerodynamic improvements were made, the same prop with as much as 62 pitch became common.
    With the 56 pitch the average S1S would turn 3500 r/m at 200 indicated. At 180/185 it felt like a drag chute had been deployed. One very basic change, to a 58 pitch, transformed the airplane. Now 200 indicated could be achieved quite easily. Climb and low speed aerobatic performance suffered. A crossover exhaust restored the climb and low speed performance to a level very close to the 56 prop.
    In the mid to late 70's virtually everyone flying a S1S was turning 3300/3500 rpm for aerobatics.
    Gene Soucy, Tom Poberezny, Bob Herendeen, Marion Cole, one could tell just by the sound that they were turning 3500.
    The Marion Cole power management protocol:
    There are two levers, lever A and lever B. Push Lever A all the way to the stop and leave er be.
     
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  16. May 10, 2018 #16

    Jean-luc

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    Grassroots,TFF1
    Thank you for the great advices.
    Now,i understand why Rupert suggest me to talk about that with experienced Pitts pilot.I don't have any experience flying a Pitts as i currently build it.
    Of course,an engine doesn't need to have more power than the propeller can take or use.
    I sent a message to Rupert to ask him if the 2800 rpm are a limitation .
     
  17. May 10, 2018 #17

    Jean-luc

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    Jim
    I must admit that the propeller is the more complicated item of the aircraft !!!!
     
  18. May 10, 2018 #18

    grassroots

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    200HP angle valve or parallel valve with higher compression cylinders? The latter will be stronger. If your engine will have a heavy flange, make your life easier and just use a metal Sensenich between 58-60, depending on the answer to the question above. Even if you have a light flange, you might want to start out with a serviceable Sensenich and fly it until you have enough experience in the airplane to figure out if your flying style truly requires a different prop or pitch.
     
  19. May 10, 2018 #19

    Jean-luc

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    Parallel valve with higher compression cylinders with Lycon's parts or ACE Performances cylinders/Pistons.As you advise,i will choice a heavy flange.
    Sure the Sensenich can be a very good choice,as it seems to be the reference for all other Pitts propellers.So why an Hercules prop;because it's made in Europe,and even a used Sensenich send from the US will cost me more with shipping and taxes than a new Hercules.
    The GT 3 blades propeller could be a good choice,but cost 6000 Euros when the Hercules cost 2500 Euros
     
  20. May 10, 2018 #20

    jrs14855

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    I neglected to explain what most probably know. Above around 3300 rpm with the 76" diameter prop the tips go supersonic and prop efficiency drops dramatically.
    Regarding power, the 0 360 parallel valve engine power curve does not simply end at 2700 rpm. The power curve may shallow out a bit but the horsepower continues to increase. So the optimum performance for aerobatics is obtained with a 76 diameter prop right around 3300 rpm.
    The F1 and Biplane racers uses shorter props because the mission is different. Low speed performance is not a significant factor. So the F1's turn 58" props as high as 4200 rpm. The Lycoming powered biplanes somewhat less, but still way above rpm's seen in aerobatics. The 0 200 in the F1's is putting out at least 125 hp, probably a lot more. On some occasions the Gold biplanes are going faster than the Gold F1's.
    It is also good to remember that the ancient geared Lycomings ran in the 3500 r/m range. This was possible because the gearing allowed a large diameter prop turning a relatively low r/m.
    A Cassutt racer is an interesting comparison to a stock Pitts S1S. With a stock Continental rated at 100 hp and a custom metal prop the Cassutt will have a rate of climb very close to the Pitts. Pulling vertical in the Cassutt at 270 indicated the Pitts will be far behind. The Cassutt is a great airshow airplane but not a good competition airplane.
     

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