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Old Dec 22, 2012, 10:53 AM
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yalex,
I think you are right on with the drive. Only two fwd/1 reverse speed is plenty to control speed on a model this massive. Very cool stuff with that laser cutter.
Wish I had CAD ability, laser cutter and 3D printer...real 21st century modeling!

Since you have so many masts and yards, maybe brace tension on all the yards would be hard to control with the sliding servo setup alone. I have to tweak alot just to get 2 masts with only two controlled yards each to be all in tune. You might try individual brace tension like shown in the attachmnet. The spring/bungee could be alomgside the mast above deck as shown or all below deck. Should work OK. Also adds a bunch of lines aside the mast, just like prototype appearance. Just a thoughgt....
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Old Dec 25, 2012, 04:48 PM
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los angeles
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Dan: thanks for your support. I am actually working on changing my control setup to take advantage of your system (you could/should get it patented). Originally, a different setup was planned. I will post the details soon. Meanwhile, would you recommend putting both mainmasts (they are the same size) on the same servo, or should I try to squeeze in two servos and run the from a Y-harness? I can also connect them to separate channels an control both from the same stick on the Tx. Originally I planned to simply connect the corresponding yards with thin line.

Thanks for your help

Alex
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Last edited by yalex; Dec 25, 2012 at 05:01 PM.
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Old Dec 25, 2012, 10:23 PM
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Yalex,
If you have the channels and a programmable Tx, I would definitely go with a seoparate servo per mast.
With ability to slave channels and to adjust slave response level to master, you can electronically tune your yard rotations - much easier than trying to get drums, rigging geometry, etc etc matched mast-to-mast. No matter how similar the geometry, I find that there is always assymetry in rigging performance mast-to-mast and side-to-side. Too many variables to have everything symetrical.
On this big a model, with all that potential sail area, I think you will really need the full power of a servo on each mast. I've had great luck with the HS785HB
http://www.servocity.com/html/hs-785...rotations.html
It's $50 at Servo City - a great price for the quality and features of the servo. Haven't destroyed one yet.
You will have the room for the servos. You will still need to have slack control, etc., but I really think separate servos is the way to go.
Alternate perspective: if somewhat prototypical brace rigging is not a priority, then try simply stringing the yards together as a first approach, but leave room for the changeover to separate servos if more servo power is needed.
I've re-rigged and changed Syren many times. Leave things open for changes as you learn how well things work when actually sailing.
Should be an absolutely beautiful model to see on the water!
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Old Dec 26, 2012, 04:01 AM
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It's your hobby, so you can make it as simple or complicated as you wish.

From a sailing and maintenance point of view, simplification is good. Adding separate controls for the separate masts is only necessary for the foremast vs. Everything aft of the CLR, i.e. 2 servos will do the job. Everything aft of the CLR needs to be moved as a unit, so if one servo will do the job, why add another? On my 1:100 scale Pamir, Main, Mizzen, and Jigger are all slaved to the same servo: the main and mizzen by lines connecting yardarms, the jigger by a separate line from the servo arm.

On Pamir, the servos are, in fact, the smallest metal gear servos, the micro size HS-82MG. The forces on square sails are balanced, compared to the forces on a fore&aft sail. The same 82MG micro servo that moves yards easily on Pamir is barely able to handle the mainsail&jib of the bottle sandbagger, for instance. In contrast to the sloop, I've never been hampered by micro servos in adjusting the squarerigger braces (unless my batteries are low, but that would affect any size servo). My 1:40 scale Aldebaran uses the next size stronger servo, the HS-225MG. With only 2 masts, yard slaving is not appropriate (masts are on opposite sides of the CLR), but I bet I could run both masts off one servo if I had wished.

Adding a servo so as to fine-tune yard trim on Pamir is not necessary. The forces on the yards when on a beat (where you will spend 80+percent of your time) automatically swing the yards to their most sharply braced position (showing that the forces on squaresails are not Entirely balanced). When I was free-sailing Pamir (prior to RC-ing her), and when I freesail the bottle brig and the brigantine, it is never a problem to get the yards to assume the correct position for a beat. The only concern is keeping the yards from swinging too far if the yard swing is not hampered by shrouds. I limit yard swing mechanically (my jaw-jammers), not by trying to fine tune the joysticks - once the ship gets 50 feet away from my eye, I could not see the fine tuning necessary anyway.

The only purpose in RC-ing the yards is to enable the skipper to swing them for tacking and wearing. Here, the boat is in stays for such a short time that any minor mis-adjustments of brace tension are never a concern. The only concern is if the braces develop a lot of slack (due to stretching of line or slippage of line-length bowsies). Adding a servo will not affect slippage or stretching, so won't improve sailing performance.

I don't know how winch power compares to servo arm power, but I'd expect the winches to be at least as powerful as servo arms. Note too that the parallogram method of bracing, used by servo arms, puts the servo at a leverage disadvantage compared to winch bracing (where the leverage is as favorable as it's ever going to be). Nothing wrong with using strong servos, but I've never seemed to need them. If DanL says you need strong winch servos, I don't disagree with his experience. Perhaps the frictional losses are higher. But the sailing physics are the same, so from a sailing point a view, small is beautiful.
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Old Dec 26, 2012, 08:54 AM
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Brooks reply is excellent - better advice than mine. I really have little sailing experience compared to Brooks, Paratrooper and others, and experience with only one model - the SC&H brig.
On the brig, with the yards hitting the shrouds and the particular brace geometry, it takes a bit of force to pull the yards to the fully braced position. But the fact that I never have blown a servo indicates the load on them is likely way below what they can do.
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Old Dec 26, 2012, 09:41 AM
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Dan, Brooks: this is why I am doing this log, to get the opinions of the more experienced modelers. In fact, I have been changing my initial controls design to accommodate Dan's Pattented Miracle Sliding Servo System. Now I have changed it again, to accommodate separate servos for two aft squareeigged masts (main and mizzen or two mains, usingRussian designation, as on the original). I will not install the mizzen servo yet. I will try to see how everything works with one servo for both masts. But I will have the space for it. In my modeling I am very big on overkill. I am trying to make my models extra strong, extra stable, use extra strong servos, etc. I still remember my first rc sailboat, Victoria with a standard servo and servo arm that could not move the sails in anything but the slightest of zephyrs. I will see if one servo works. If it does, I will not complicate me life any further. If I need more bang, I'll be prepaired.
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Old Dec 26, 2012, 11:21 AM
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An observation on brace slack:

There are 2 types of slack, a) leeward brace vs windward brace (which I'll call right/left problem), and b) braced square vs. braced off square (run/beat problem). The braces leading from the yardarm to a centrally placed servo form triangles, so the brace lengths are going to be governed by trigonometry. Think sines/cosines/tangents - none of the graphs of those functions are a straight line. So, any linear method of adjusting braces (via triangles) will have slack problems of some sort: a), b) or both. The parallelogram method avoids triangles, so avoids slack. But the p.braces are not run to the yardarms, so don't look realistic when viewed close up.

When I was building ships in bottles, I learned some things about brace lengths. The "brace" in a s.i.b. is just a line running from a starboard yard arm to a hole in the next mast aft then back to the port yard arm. The brace forms a triangle, so is subject to trigonometry. Yards must be free to swing and cockbill to get the whole shebang narrow enough to slip into the bottle. Once in the bottle, the yards are teased back into normal position. By adjusting the length of the "brace" before hand, you can use the friction as it passes through the aft mast to hold the yards in correct position once the model is in the bottle.

Now for the learning: if the braces are of a length to hold the yard square with a *little* tension on them, they will be way too long when the yard is sharp and cockbilled - just what we want for s.i.b. work. If the braces were tight enough to hold the yard in a correct braced sharp position (just what we want for actual sailing), though, they would be *way too tight* in the braced square position; in fact they would bend the yard, maybe even snap it in two, oops. I certainly snapped a few s.i.b. yards learning this lesson.

What DanL's new servo setup does is correct for the way too loose/way too tight situation, that is the b) run/beat problem. What his setup won't do is correct for the a) situation, though. Since the servo sled will simultaneously tighten both sides, or loosen both sides, as it slides, it can't fix right/left problems. Those will still be handled by bungee ends on each port and starboard brace.

The Jarvis winch was designed to handle the right/left problem. Using coned drums, the winch would adjust right/left braces differently, particularly as the yard swung closer and closer to the beat (braced sharp) position. However, sailors writing about using the winch said that they still had to individually adjust each brace a little bit to get everything perfect. The Jarvis brace setup led one end of the brace to the cone, and the other to a belaying pin. The sailors would adjust the belaying pin end, exactly analogous to DanL's bungee cord setup :-). The cones themselves need to be parabolic in shape to solve both a) and b), a feature that was too expensive, I guess, to implement. With parabolic cones, the problem of line under/over-run on the drum is worse than with straight cones; an under-run line may jam, and that would be intolerable at sea.

So, DanL, your need for adjustments of each yard, even with the new sleds, is true to life, if that's any consulation *smiles*. The farther the yards swing, the worse the right/left problem. If your yards don't swing much past 45deg, then the sled by itself may take up most of the slack. With 50deg yardswing, perhaps the right/left problem is not too bad. But the run/beat problem will always be present, and the sled will fix that, Well Done DanL.
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Old Dec 27, 2012, 12:45 PM
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Dan, Brooks: In my original control design I used a system that compensated for both problems. However, it reqires a lot of space fore and aft, has a lot of moving parts and friction. It is also prone to snagging. It consists of an endless loop that runs from a multi-turn winch. The loop moves a shuttle that slides on a long rod (as long, as a total trim distance of my braces). On either side of the shuttle there are sliders to which the braces are attached. When the winch is activated it moves only one slider. The other one (connected to the lazy brace) is free to create as much slack as needed. I have used this system on my topsail schooner, and it works well, except for all the above mentioned negative points. The worst is, of course, the need for a very long rod. It takes a lot of space, and makes acess dificult. That's why I am so enchanted with Dan's new sliding system. But the shuttle is still the best way to control crossover jibs. In my redesign I will definitely leave one shuttle for the head sails.

Sorry, no pictures now. Will post them ASAP
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Old Dec 27, 2012, 07:22 PM
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"What DanL's new servo setup does is correct for the way too loose/way too tight situation, that is the b) run/beat problem. What his setup won't do is correct for the a) situation, though. Since the servo sled will simultaneously tighten both sides, or loosen both sides, as it slides, it can't fix right/left problems. Those will still be handled by bungee ends on each port and starboard brace."

Brooks - so as not to hijack this thread, se my thoughts on this on the Syren thread.
Thanks,
Dan
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Old Dec 27, 2012, 08:14 PM
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Quote:
Originally Posted by DanL View Post
[I]...so as not to hijack this thread...
Hijack away guys! I am learning a lot even from disagreements.
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Old Dec 27, 2012, 08:27 PM
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As you have seen in the pictures I posted, I am planning to use a geared motor to control the head sails. It is something of an experiment. The motor with it's gears came from a dead inljet printer. It is bigger than anything that goes into a servo. And the gears do slow it down quite a bit. I am controlling it with a micro servo that connects the motor to the battery, changing polarity according to the position of the stick on the Tx. To make sure that it does not run too far in one direction I installed diods and micro switches that get triggered at the extreme positions of my shuttle system. I tested the setup and it works fine. The big advantage is that I do not need to play with drum diameters. It just runs the whole length of my rod until the microswitch is tripped, and than it can only run in the oposite direction.
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Old Dec 27, 2012, 08:47 PM
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Old Dec 27, 2012, 08:48 PM
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Yalex,
Not a disagreement, just a difference in observation. And if a disagreement, a very pleasant, non-Congessional one!
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Old Dec 28, 2012, 12:35 AM
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Quote:
Originally Posted by DanL View Post
... a very pleasant, non-Congessional one!


Dan, what do you think of my proposed redesigns? I am leaning toward revision E with 3 staggered sliding servos. I can leave one servo out and see if all the aft squares can be controlled by one HS785HB servo. Do you think I can control all those sails with two pairs of braces per mast? Maybe I can attach the lower braces to lower topsail yards instead of courses?
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