How much rudder throw?

Discussion in 'Propulsion' started by Cannonman, Nov 8, 2012.

  1. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    What is everyones thoughts/ recommendations on a starting point for rudder throw/ travel on a typical big gun ship? I'm trying to finalize my rudder and servo configuration and have no idea what angle to each side from center works well for you guys.
     
  2. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    The answer is it depends, greatly on the particulars of the ship and rudder geometry. A few years back I ran some CFD studies on different rudder shapes (best then implemented by tugboat with good success) and depending on the rudder you could stall the rudder as early as 45-50 degrees off axis or as late as ~75-80 degrees off the centerline. I've always put a lot more throw than needed and then run the boat to find the best turning point.
     
  3. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    I would like to know which ship you're building so we can know how many rudders and props.

    Typically I (like Greg) build in way more than I need, and dial it down to best effect.
     
  4. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    Or curve it down, sometimes 90 degrees off is handy as a brake. I like to set a curve so there is a flat region at max turning then I can go past it into brake region
     
  5. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    Current builds are both big gun ships, first is Emile Bertin - 4 props, inner two powered, single rudder. The second ship Tuggy should be familiar with, Russian Orfey class, as designed by Webwookie. Two shafts, both powered - (I screwed up and didn't make the shafts counter rotate when I built the gear box, don't know what the effects of that will be.) It is also single rudder. I am currently working on the destroyer, and due to the maximum rotation on the servo, I'm not getting as much throw as I was hoping for, even with the radio end points maxed out - unless someone knows of a way to get more out of the radio (Turnigy 9x) - possibly with different firmware? I have end points set to 120, and am getting *maybe* 100 degrees total swing, roughly 50 degrees to each side - (just guessing, I didn't measure it yet) I was hoping someone would say that's all I would ever need, but probably knew better! :) The servo has the physical capability to go near 170 degrees total before it hits its stop, so I think I could get a servo stretcher from servo city, but it adds complexity, is one more thing to waterproof, and more importantly takes up weight and space in a ship that is fairly limited in those attributes.
     
  6. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    Current builds are both big gun ships, first is Emile Bertin - 4 props, inner two powered, single rudder. The second ship Tuggy should be familiar with, Russian Orfey class, as designed by Webwookie. Two shafts, both powered - (I screwed up and didn't make the shafts counter rotate when I built the gear box, don't know what the effects of that will be.) It is also single rudder. I am currently working on the destroyer, and due to the maximum rotation on the servo, I'm not getting as much throw as I was hoping for, even with the radio end points maxed out - unless someone knows of a way to get more out of the radio (Turnigy 9x) - possibly with different firmware? I have end points set to 120, and am getting *maybe* 100 degrees total swing, roughly 50 degrees to each side - (just guessing, I didn't measure it yet) I was hoping someone would say that's all I would ever need, but probably knew better! :) The servo has the physical capability to go near 170 degrees total before it hits its stop, so I think I could get a servo stretcher from servo city, but it adds complexity, is one more thing to waterproof, and more importantly takes up weight and space in a ship that is fairly limited in those attributes.
     
  7. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    I should mention that since I'm big gun, rudder and prop locations are per scale, rudder size was increased whatever I was allowed, I think 25%.
     
  8. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    see servocity. on some analog and digital servos there are options to either reprogram the servo or modify the servo for extended range, or add a servo extender to get more rotation. more =+/-90 vs +/-45

    http://www.servocity.com/html/hs-5086wp_servo.html

    http://www.servocity.com/html/hs-646wp_servo.html

    http://www.servocity.com/html/180o_servo_stretcher.html
     
  9. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    I would also say the custom firmware is sweet. I've been adding my own code to the open9x firmware lately with some good success
     
  10. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    I've checked out servo city. They offer the servo I'm using on Emile Bertin in a 180° modded version. I'm assumming I could add some resistors to the one I have to get the necessary rotation, the destroyer is a different animal though. Servo city lists the servo I'm using as not able to be modified. Since it has plenty of physical travel, I have to guess that the problem is I'm fitting resistors in the tiny case :( I am hoping to flash my radio this weekend possibly, I've acquired a programmer, just need to put it in and read up on the procedure.
     
  11. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    if you have the smartieparts board, the proc is easy
     
  12. Tugboat

    Tugboat Facilitator RCWC Staff Admiral (Supporter)

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    Is it available again?
     
  13. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    come and gone probably. he gets them in frequently so I just backordered one and 3 weeks later I had it. If you don't have the 9x, I would wait till the 9xR comes out in the near future... rumor has it same firmware support as far as the open source firmware is concerned but built in programmer
     
  14. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    well low and behold. , they are in stock
     
  15. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    Yep, snagged the latest and greatest Smartie Parts board :) should be easy to put in, the hard part is deciding which firmware to use.
     
  16. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    Well, I've been using and modifying Open9x firmware. I really like it and the fellows who have been developing it have helped me with the modifications by changing the code to make my changes easier... Plus companion9x is sweet. Getting the code to compile (from any of them) , OTOH not as sweet, but working now
     
  17. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    I'll have to check out the open9x. I was looking into er9x, which is rumored to provide more servo travel, so much to the point that a post i just read said to be careful when going over 100 on end points because it will damage some servos due to overtravel if the internal stops limit travel too much. Might be right up my alley. I also found that Hitec has just introduced a digital version of the servo I'm using (I'm using Hitec HS 35 - digital version is HS 5035), but I can't find a travel spec on it yet. I'll try some firmware first, if that wont get me what I need, I guess I can try the digital servo. I'm kind of locked into this exact size servo, since its all built and jammed into the rear of the boat. I'd have to redesign and rebuild the mounts to change now..... I'd rather avoid that!
     
  18. GregMcFadden

    GregMcFadden Facilitator RCWC Staff

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    http://code.google.com/p/companion9x/

    https://code.google.com/p/open9x/
     
  19. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    Thanks Greg! Got my SmartieParts Board and my backlight in today. Finally took a little time to look into the firmware and did go with the open9x. The good news is that between the new firmware and maxing out the extended end points, it seems like I'm getting close to 140 degrees total travel. I think its enough now! :woot:
     
  20. Cannonman

    Cannonman Ultimate Hero :P -->> C T D <<--

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    [​IMG]


    Here's a shot of the rudder at maximum throw. Far enough?