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Old Jan 10, 2011, 06:20 PM
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Personally, I think that turning the masts would be harder than running braces. It's pathetically easy to use braces, actually, especially if you mount the servos on deck and use parallelogram motion, like I did for my Bottle Baltimore. For some additional complication (more braces), see my Pamir; Pamir started simple (like Baltimore), and then I got "creative" for the fun of it :-). That is, you can rig as simply as you like, and get a working ship, and later you can add more rigging if that's your fancy.

Mounting the servos below deck adds to the scale looks, at some cost in building complications. My Aldebaran has a hollowed-out, solid wood hull (made from bread and butter layers rather than a single baulk), so is similar to your Beagle. I'm pleased with the servo sail-handling of all 3 ships.
Bottle Baltimore:
http://www.rcgroups.com/forums/showthread.php?t=1071509
Pamir:
http://www.rcgroups.com/forums/showthread.php?t=743611
Aldebaran:
http://www.rcgroups.com/forums/showthread.php?t=1096365
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Old Jan 11, 2011, 09:25 AM
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Brooks

Darn you! Now I'm debating which way to do it lol. I've actually read through most of your threads already. You and posters like Paratrooper have been a major inspiration for me tackling this project.

Whichever way I go, I need some advice on what brand/model of radio system to use. I see the Futaba brand mentioned often so I might start there. I want to get something with a lot of channels that I can use for many years and with potentially multiple model ships. Any advice?
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Old Jan 11, 2011, 04:33 PM
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I've done a little more research and I'm leaning toward either the Futaba 7 or 8 channel 2.4GHz systems with four high torque servos. So I'll be using three channels for the sails, one for the rudder, one for a back-up/clip-on propeller, which leaves 2 or 3 channels for something else.

Anyone have a favorite high torque servo? They seem to come with a standard 60 degree rotation, so I need to figure out how to get something closer to 90. (I'm starting to understand why some people's builds take years to finish lol.)
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Old Jan 11, 2011, 10:11 PM
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The servo torque requirement is less for square sails than for fore&aft sails. This is because square sails are somewhat balanced, allowing the wind to provide part of the force for bracing. In contrast, f&a sails are always unbalanced, so need more servo power.

My Pamir uses two Hitec HS-81MG (Metal Gear) Micro servos for all sheeting (foremast squares & jibs, main & mizzenmast squares & f&a jigger), and a stronger, mini servo, HS-225MG, for the rudder (to allow sculling). Aldebaran uses four HS-225MG servos for all controls (foremast squares & jibs, mainmast squares, f&a mainsail, rudder).

There is no need to buy special high torque servos for squaresails, if you use parallelogram bracing, at least based on my experience. I do think it's worth the extra expense to get metal geared servos, though. They are less likely to strip teeth when sails start slatting, or when you need to rotate the yards by hand (eg before laying the ship down on the grass if the Rx gets wet and quits working). I'd expect that the HS-225MG's would suffice for Beagle.
-------------
I forgot to say that your ship looks very nice!
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Last edited by Brooks; Jan 11, 2011 at 10:32 PM.
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Old Jan 12, 2011, 10:43 AM
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Hi, this may not be one of my brightest days - please explain "parallelogram sheeting" to me!
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Old Jan 12, 2011, 11:09 AM
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parallelogram bracing is a short-cut way to deal with the geometry of bracing yards on a model to get around the fact that you can't make a servo arm inside the hull as wide as where the braces prototypically attach to the yard.

That is; if the braces would attach 10 inches from the center on the yard, you'll never get a 10 inch servo-arm inside an 8 inch wide hull. So, you attach the braces to the yard 8 inches out to match your servo-arm. Schematically the braces, yard, and servo-arm form a parallelogram.

This is the stock set-up used on for SC&H brig and Surprise models.
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Old Jan 12, 2011, 10:17 PM
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Parallelogram bracing

diagram of the bracing method.

Pamir routes braces via brass screweyes and brass rods. Pinching the parallelogram affects the motion somewhat, so rods that allow braces to slide athwartships as they are adjusted give a more pure parallelogram motion. Pure motion gets the most yard swing out of a servo arm. Incidently, the servo arms on Pamir are only 2.5" long, for a 1" throw on either side of the center screw. The braces, correspondingly, attach to the yard 1" to either side of the yard truss.

However, if you have a way to magnify servo motion, say through the use of a "servo doubler" or through use of "2:1 reeving", you can dispense with pure parallelogram motion.

Bead block pendants work fine, look more realistic than brass bars, and are the method I use in Bottle Baltimore and Aldebaran. The servo arms on Aldebaran are as long as I could squeeze between the sides of the hull, about 4". With 2:1 reeving plus servo doublers, I could move the braces out along the yard, farther from the yard truss, making for a more realistic look.
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Old Jan 12, 2011, 11:27 PM
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Brooks

How much angle from perpendicular do the sails of your ships achieve?

If I mount the masts on the servos I should in theory be able to get a full 90 degrees if the servos can turn that far. The Futaba 7-channel I'm looking at comes with different options of servos, one of which is four high torque ones, but they are all 60 degrees rotation.
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Old Jan 13, 2011, 04:32 AM
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thats 60 total, so 30 on each side. you`ll need as much as you can get 55-60 to each side from perpendicular.

Brookses and my braces (i use his system of bracing) with 2:1 reeving and servo doublers (stretchers) get about 60 swing each side, probably a bit more depending on how much slack there is in your braces
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Old Jan 13, 2011, 10:08 AM
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meatbomber

Ahhhh... so all the servos that list as 60 degrees only turn 30 degrees left or right? (I'm such a noob).

Maybe I'll look into a continuous rotation servo. Boy am I glad you guys are here to help.
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Old Jan 13, 2011, 10:21 AM
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correct. you can get so called servo stretchers that will make them travel up to 180 from a 90 servo, depending on it`s mechanical limits.

http://www.servocity.com/html/180o_servo_stretcher.html
dunno how well these work as servo city doesn`t ship overseas unfortunately so i have different ones, but overall they should be quite the same (mine are not adjustable)
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Old Jan 13, 2011, 11:17 AM
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meatbomber

I see in that article for the servo stretcher that it says: "Digital servo can be programmed electronically for 180 rotation."

When I look at a review ( http://www.rcuniverse.com/magazine/a...article_id=965 ) for programming the airplane version of the Futaba 7C it says:

"End Point of servo travel adjustment: the most flexible version of travel adjustment available. It independently adjusts each end of each individual servo's travel, rather than one setting for the servo that affects both directions."

"Sub-trim: makes small changes or corrections to the neutral position of each servo. Range is -120 to +120, with 0 setting, the default, being no Sub-trim."

I can't tell from all that if I can take one of the Futaba servos and program it for 180 rotation or not.
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Old Jan 13, 2011, 12:09 PM
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Subtrim units are just the number of steps the transmitter decides the servotravel in. My Spektrum Radio does 150 each side if I recall correctly and a travel adjustment of 125% both ways but that only means a 90deg servo travels about 60deg with normal travel and maxed out gives 90.
Dunno with the DIGI Servos, all that I have are non ptogrammable
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Old Jan 13, 2011, 12:20 PM
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Btw does anyone know someone who has mounted their masts directly on the servos like I'm thinking of doing? The only one I've found is John-Tom's Brigantine "Edith Ann" (http://www.john-tom.com/RcShip/RCship.html ), but I can't really tell from his pics how he actually did it.
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Old Jan 13, 2011, 12:41 PM
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Brian Clark's probably done the nicest job of directly driven yards on his Susan Constant.

He went away a few years ago and no one's heard from him since, so I don't know if we'll ever see it finished.

I did a much smaller and rougher version of that system in a couple of plastic models, discussed in the Constellation thread starting about here.
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