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    Analog or Digital
    by MouldBuilder ๐Ÿ‡ฌ๐Ÿ‡ง ( Sub-Lieutenant)
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    10 Posts 9 Replies 1 Photo 18 Likes
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    RNinMunich
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    ๐Ÿ“ Analog or Digital
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
    Online: 3 hours ago
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    I remember seeing a Gato docked alongside the Brazilian Navy Museum in the Arsenal do Marinha in Rio in the nineties. Opposite the Corvette Barosso which I was working on.
    Maybe that was Drum?? NOPE! Just found her, she's in Alabama US of A!
    https://www.google.com/maps/uv?hl=en&pb=!1s0x889a4ff6ca92b5b...
    Don't think the railings or telescope are original though!๐Ÿ˜ฎ
    Doug ๐Ÿ˜Ž
    https://www.google.com/maps/uv?hl=en&pb=!1s0x889a4ff6ca92b5b1%3A0xc69366f5fc25f076!2m22!2m2!1i80!2i80!3m1!2i20!16m16!1b1!2m2!1m1!1e1!2m2!1m1!1e3!2m2!1m1!1e5!2m2!1m1!1e4!2m2!1m1!1e6!3m1!7e115!4shttps%3A%2F%2Flh5.googleusercontent.com%2Fp%2FAF1QipNdCkiprY9drRV2J4aDmUnrrpOqdTl9e4hgDyYt%3Dw130-h87-n-k-no!5suss%20drum%20museum%20-%20Google%20Search!15sCAQ&imagekey=!1e10!2sAF1QipNdCkiprY9drRV2J4aDmUnrrpOqdTl9e4hgDyYt
    ๐Ÿ”—
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    MouldBuilder
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    Just read your link. Drum still exists in a museum. My Gato will be SS 228 Drum. Thanks for helping me decide.๐Ÿ˜Š
    2
    I promise I will finish a boat project before I start another......Maybe.
    MouldBuilder
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    The names supplied in the kit are SS 218 ALBACORE and SS 228 DRUM. Probably have to be one of these if I want to use the decals.
    2
    I promise I will finish a boat project before I start another......Maybe.
    MouldBuilder
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    I certainly will Doug.
    As for the name, I will choose one that is still around. That way there is no history of it sinking permanently.
    I have ordered some 7kg digital mini servos as you suggested. Thanks for your help.๐Ÿ˜Š
    2
    I promise I will finish a boat project before I start another......Maybe.
    RNinMunich
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    Glad to help Peter,
    Just "repay" me with a great vid of Gato's sea trials please๐Ÿ‘
    What will you name it? Selection list below. From
    https://en.wikipedia.org/wiki/Gato-class_submarine#Ships_in_...
    Personally I would go for Harder or Wahoo๐Ÿ˜‰ Then I'm biassed having recently seen both in episodes of "Hell Underwater".
    Cheers, Doug ๐Ÿ˜Ž

    "Albacore sank the Japanese aircraft carrier Taiho. Taiho was the flagship of Vice-Admiral Jisaburo Ozawa's fleet during the Battle of the Philippine Sea.
    Barb, on her 12th patrol in July 1945, landed a small team from her crew on the shore of Patience Bay on Karafuto. They placed charges under a railroad track and blew up a passing train. The Barb also conducted several rocket attacks against shore targets on this same patrol, the first ever by an American submarine. They used 5-inch unguided rockets fired from a special launching rack on the main deck.[35]
    Cavalla sank the Japanese aircraft carrier Shokaku. Shokaku was one of six Japanese carriers that had participated in the attack on Pearl Harbor.
    Cobia sank a ship carrying Japanese tank reinforcements which were en route to Iwo Jima.
    Cod went to the rescue of a grounded Dutch submarine O-19, taking its crew on board and destroying the submarine when it could not be removed from the reef, the only international submarine-to-submarine rescue in history.
    Corvina was the only U.S. submarine sunk by a Japanese submarine (I-176) during the Second World War.
    Darter along with Dace conducted an aggressive and successful attack against Japanese fleet units during the lead up to the U.S. invasion of Leyte Island in the Philippines in October 1944. The two boats sank the heavy cruisers Atago and Maya and severely damaged the heavy cruiser Takao. A few hours later, while maneuvering back to the scene to finish off the crippled Takao, Darter ran hard aground on Bombay Shoal off Palawan. Her entire crew was rescued and subsequent attempts to destroy the wreck were only partially successful.[36] As late as 1998, portions of Darter's hulk were still visible on the reef.
    Finback recovered downed pilot LTJG George H. W. Bush, future President of the United States, after his Grumman TBM Avenger torpedo bomber was damaged and eventually ditched during a bombing mission at Chichi-jima in the Pacific.
    Flasher was the top-scoring U.S. boat of the war, with 100,231 tons officially credited to her by the Joint Army-Navy Assessment Committee JANAC.
    Growler's skipper, Howard W. Gilmore, earned the submarine force's first combat Medal of Honor for sacrificing his life to save his boat and his crew. Alone on the bridge after being wounded by enemy gunfire, and unable to reach the hatch after he had ordered the others below, he pressed his face to the phone and uttered the order that saved his boat and sealed his doom: "Take 'er down!"
    In Grunion, Mannert L. Abele earned the submarine force's first Navy Cross, when his boat engaged in a running battle with Japanese ships off Kiska in July 1942. Grunion was subsequently lost in this action. In 2006 and 2007, expeditions organized and led by Abele's sons, Bruce, Brad, and John, located and photographed the wreck of the Grunion using side scan sonar and a remotely operated vehicle (ROV).
    Halibut was essentially the 53rd U.S. submarine loss of the war. Terribly damaged in an aircraft-borne depth charge attack on 14 November 1944, she barely limped back to port in Saipan. Temporarily patched up, she was sent back to the United States. Examined by engineers, she was found to be beyond economical repair and was decommissioned on 18 July 1945, never having made another war patrol. Her entire crew survived.[37]
    Harder was commanded by Samuel D. Dealey, the only submarine commander of the war (perhaps the only one ever) to sink five enemy destroyers, four in a single patrol.
    Mingo, which sank two Japanese ships during her patrols, was lent to the Japanese Maritime Self Defense Force after the war, serving under the name Kuroshio.
    Trigger became famous in Edward L. "Ned" Beach's book Submarine! (which was a kind of eulogy to her).
    Tunny sank the Japanese submarine I-42 on the night of March 23, 1944, after the two subs dueled for position for over an hour. A week later Tunny engaged the battleship Musashi and inflicted enough damage for Musashi to return to dry dock for repairs.
    Wahoo, commanded by one of the submarine force's most famous skippers, Dudley W. "Mush" Morton, engaged in a running gun and torpedo battle with a convoy of four ships off the coast of New Guinea and destroyed the entire convoy. She was also one of the first U.S. subs into the Sea of Japan. She was sunk while exiting the Sea of Japan through the La Perouse Strait in October 1943 while on her seventh patrol."
    https://en.wikipedia.org/wiki/Gato-class_submarine#Ships_in_class
    ๐Ÿ”—
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    MouldBuilder
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    Makes perfect sense. Thanks Doug.
    That makes me worth 6 quid also then.๐Ÿ˜
    2
    I promise I will finish a boat project before I start another......Maybe.
    RNinMunich
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    Hi Peter,
    The planes aren't very big I guess so the 2.7s should be OK๐Ÿ‘
    No scientific basis, just gut feeling๐Ÿ˜‰
    Important is the faster response and higher precision of the digital servos for small auto-corrections around the set point๐Ÿ˜Š
    Just remember when connecting the servo arm that the torque is usually quoted as or kg x cm or Newton x metre (pound-foot in Imperial)!
    (Guess at 6'2" that makes me worth about 6 quid!๐Ÿค”)
    I.e. 2.7kg at 1cm from the centre of the servo output shaft.
    So if you connect the push rod at the extreme end ca 2cm the torque (and holding power) halves to 1.35kg!
    If in doubt go for a mini which won't take much more space and should give about 4 to 6kg/cm.
    Servo torque is often quoted at 4.8V (standard 4 cell NiMh pack) or 6V (SLA or UBEC).
    Run the servos on 6V if possible for the higher torque and lower current.
    Hope this helps, rather than confusing further!
    Cheers, Doug ๐Ÿ˜Ž
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    MouldBuilder
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    Thanks Doug. This is very helpful.
    I would like to use a Micro 2.7kg digital servo for the planes. Do you consider this to be enough or should I go for a standard servo for the extra power, say 9kg.
    Thanks, Peter.๐Ÿ˜Š
    1
    I promise I will finish a boat project before I start another......Maybe.
    RNinMunich
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    Mornin' Peter,
    Go digital young man!! The RX doesn't matter, as long as it matches the TX modulation, i.e. FM/PPM or PCM. I understand that your Optic 6 can be switched for either of these modes.

    Especially for the trim (dive) planes and rudder of a sub the faster response, more precise positioning, and greater holding power (torque), of digital servos is important to resist the forces created by underwater currents and the boats drive power.
    Here is an excellent explanation of servos in general and advantages of digital servos.
    All based on helis but equally applicable to large or fast model boats and subs.
    https://www.rchelicopterfun.com/rc-servos.html
    There are also two vids showing the difference in action and scope displays of the control signals.
    Basically you could use either type in your sub but the analogue type is sort of spongy and vague around the centre point. Exactly where you need precision to trim the boat and keep it stable. I like this description of a practical test for this. Cheers, Doug ๐Ÿ˜Ž PS there ain't no such thing as a "Free lunch". Same with Digital servos, only disadvantage is that the faster motor control and higher holding torque uses more battery power than Analogue types. So make sure you won't exceed the current limit of your BEC or UBEC. Another reason why I prefer a separate RX battery ๐Ÿ˜‰

    "Digital RC Servo Operation
    Digital servos to the rescue! Like I said before, a digital servo has all the same parts as an analog servo, even the three wire plug that plugs into the receiver is the same. The difference is in how the PWM signal is processed and sent to the servo motor.

    A small microprocessor inside the servo analyzes the receiver signals and processes these into very high frequency voltage pulses to the servo motor. Instead of 50 pulses per second, the motor will now receive 300 and up pulses per second.

    The pulses will be shorter in length of course, but with so many voltage pulses occurring, digital servos have much improved deadband, better resolution, faster response, quicker and smoother acceleration/deceleration, and immensely better holding power.

    You can test this very easily by plugging in a digital servo and an analog servo to your receiver. Try to turn the servo wheel off center on the analog RC servo.

    Notice how you will be able to move it slightly before the servo starts to respond and resist the force - it feels a bit "spongy".

    Now do the same thing with the digital RC servo. It feels like the servo wheel and shaft are glued to the case โ€“ it responds that fast and holds that well."
    https://www.rchelicopterfun.com/rc-servos.html
    ๐Ÿ”—
    2
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    MouldBuilder
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    I am seeking some advice please.
    I am going to purchase some small servos to run my Gato Submarine. I have a 40MHz transmitter, a Hitec Optic 6, so that I can receive under water. My problem is though, Analog or Digital servos. My questions are, will both work with this transmitter on 40MHz; What are the advantages of Digital over Analog or vise versa; Does the receiver have anything to do with the choice.
    Thanks.
    Peter.
    1
    I promise I will finish a boat project before I start another......Maybe.



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