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Yalex -
A few points...on my brig, and on Gary's Surprise, we want all the angle we can get on the yards to get better maneuverability (pointing higher into teh wind). Less drastic but more prototypical angles make sailing a pain given the wind conditions and space we sail in. So we modified rigging for maximum yard rotation. This is important, too, to maintain speed going into a tack because you can really come into the wind (more "schooner-like') Next point - on a real square rigger, where lowest braces go to bulwark, the geometry does work. But a lot of other stuff is going on....the tilt (of the yard is controlle d to keep it level, the brace tension is adjusted both port and starboard, sails are trimmed, etc. On my model, braces running at a downward angle were tried early on (and used until recently on the foretopsl yard), but the yards end gets pulled downward and starts messing up the yard tilt on the whole mast. On a smaller model with stiff sail material, this may not be the case. But on a big model with soft sails, etc, pulling back and downward will likely tilt the yard too much. Also, I couldn't get the angle of rotation that I get if I did not pull the braces from closer to the centerline vs at the bulwarks. Another point - if you did the test and got so much rotation on the lower yard that it couldn't be pulled back, I'm guessing that you don't have the shrouds rigged yet. If positioned right, they will block the lower yards from over-rotation. I really believe that model sqr rigger geometry needs to be modified from prototypical to make the model more practical (and fun)to sail. I've never seen more than minor mast twist on my yards - certainly never to the point where the upper yards are too parallel to the hull vs the lower yard position. And I still disagree (and I may be wrong) with the idea that the windspeed difference from lower sails to upper sails is significant at this scale. On a real ship you're talking 100++feet. On these models it's only 5-6ft. And it's not that often the topgallants are used anyway. The biggest issue is not having steady wind velocity, wind direction changes, gusting and having enough sea room and smooth enough seas to tack reliably - all the other stuff to me seems a minor factor because Syren sails like a champ if given anything near a steady breeze. See these posts for my "paper excercise" on brace pull. The system works just fine and the model measurements are very close to the design excecise. The model is now re-rigged per the drawings, with sliding servos and the foretopsl braces rigged horizontally vs the downward angle pull. I've not sailed her yet, but have run through all kinds of rotation tests, slack measurement, servo amp draw, etc and all looks really good. http://www.rcgroups.com/forums/showp...&postcount=137 http://www.rcgroups.com/forums/showp...&postcount=138 http://www.rcgroups.com/forums/showp...&postcount=139 I like your plan of starting with fewer servos and only lower braces until actually sailing to see how that works. Allowing as you are for future servo additions and redesign of rigging, you should be good to go. Then optimize rigging over the many years of enjoyavble sailing you will have! Sorry - long post, but I feel pretty confident about my experience and observations. |
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Do you have a pic or sketch of the prototype shroud/deck setup?
How close to prototype do you want it to appear? A non-prototype approach is attached. Shrouds, length adjusted, are attached to a bar. The bar is tensioned by adjusting screws. Another approach - use bicycle spoke nipples. Attach threaded rod to end of shroud and use nipple to adjust tension. Google bike nipples and you can find nipples up to an inch long for only 15-20 cents each. Black available too. Shroud frame can be slotted for easy insertion of shrouds. (Example: http://www.ebay.com/itm/7075-aluminu...-/200849409190 ) Just some thoughts.... |
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Rudder setup
Here are some ideas....
On the gear drive, you may have to flip the servo (have it upside down vs what the pic shows. Tons of linkage hardware available from www.servocity.com Gears http://www.servocity.com/html/servo_mount_gears.html http://www.servocity.com/html/32p_hitec_metal_gear.html http://www.servocity.com/html/48p_hi...tal_gears.html Couplers http://www.servocity.com/html/set_sc..._couplers.html Servo to shaft couplers (probably what you want) http://www.servocity.com/html/servo_..._couplers.html |
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4 masted barque Sea Cloud photo, base of shrouds showing bottle screw. They painted theirs black.
http://www.seacloud.com/en/die-schif...new-glory.html |
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There was a thread over on the Sailing forum discussing standing rigging failures due to improper crimping of the loop in their wire rigging. To think, they could have employed 4 seizings, per your photos, and not had failure *smiles*.
Seizing were used not only because they worked, but also for safety. It is difficult to chop through wire rigging if necessary (say in a knockdown, when the masts must be sacrificed to right the hull). A fiber seizing could be cut with knife or axe. Even a wire seizing would be easier to cut (with cold chisel) than the shroud itself. A survivor of the Pamir knockdown & sinking (1957) remembered seeing the bosun trying to cut the shrouds with an axe. The ship sank before he could accomplish his mission. I presume he was working on the seizings; cutting a wire shroud under tension would be a good way to lose your head :-/ The Pamir is an example of failure of leadership. The captain refused to give orders to save the ship, and retreated to his cabin. The cadets (Pamir was crewed with 52 cadets, plus 34 professional seamen) had no orders to launch lifeboats or anything else, apparently (no officers survived). There were only 6 survivors; the German inquiry was a whitewash, by modern standards, sigh. http://en.wikipedia.org/wiki/Pamir_%28ship%29 |
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