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Old Jul 29, 2009, 07:45 PM
Damp and Dizzy member
Brooks's Avatar
Bozeman, Montana, United States
Joined Aug 2003
3,377 Posts
servo size. beginner boat.

Thoughts on servos - Squaresails can get by with smaller servos than fore&aft sails require. Squaresails are balanced, to some extent, in a way completely foreign to fore&aft sails. Every time you haul a brace on a squaresail, needing to fight the wind forces, you are slackening a brace on the other end of the yard, and the wind forces on this half of the sail help you (and the servo). For example, my 3 ft hull barque uses Hitech's micro servo HS-82mg for braces. But the same servo is overpowered by my 1 ft hull sandbagger's fore&aft mainsail. btw, good shiphandling can allievate the forces on sails, both square and fore&aft, allowing men (and servos) some relief during a heavy haul. Spilling the wind from sails, usually by heading up, will allow overpowered servos to do their job.

This observation on servo size applies to those used in the "parallagram" bracing method. I can't comment, from experience, on winch-type servos. The balancing still exists, but servo current draws reported suggest those boats are needing lots more power than mine. They are bigger boats than mine; so, if you have a boat big enough for winches, maybe you are better off getting the strongest you can afford.

Thoughts on dipping your toes in - A topsail schooner is an easy way for a sloop skipper to get some squaresail and multimast practice. The fore&aft sails of the schooner will allow good progress to windward (keeping you off the ever-pesky leeshore). The square topsails allow one to experiment with bracing on all points of the compass. They also allow experimentation with boat heading changes via backwinding the squares. The 2 masts allow you to practice balancing forces, between the masts, to achieve course desired, a mandatory skill, I would say, for the accomplished square-rigger skipper. My bottleboat topsail schooner only took a week to build.

Topsail schooner bottle boat:
http://www.rcgroups.com/forums/showt...9#post12548314
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Old Jul 29, 2009, 09:43 PM
SCALE Sailor
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United States, MD, Severna Park
Joined Apr 2008
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Real Brace Winches

Square Rigged is a site about real square rigged sailing. Click on Jarvis under the seagull for a very nice thesis on the Jarvis Patent Brace Winch. It's full of geometry for bracing winches using conical winch drums - on real ships - much of wich can translate to model square riggers.
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Old Aug 10, 2009, 07:49 AM
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United States, MN, Brainerd
Joined Oct 2004
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Brace Travel, Yard Rotation Calculator

For calculating circle related geometry, this calculator is excellent because it calculates chords and central angles, giving good approximations of the straight line pull rewuired on a yard to rotate it thru a specific angle.
http://www.1728.com/circsect.htm

An example is how much brace travel is necessary to rotate a 27" yard (distance between points of brace connections) thru 50 degrees (100 degrees total for both directions).

Plugging in radius (13.5") and central angle of 100 degrees gives a chord of
20.7". The servo drum diameter can now be calculated. If the servo has 3.5 rotations, then the diameter of the drum needs to be a minimum of:
20.7 / 3.14 / 3.5 = 1.88"

Always allow for extar pull length to make up for line stretch, other angles in the brace geometry and because a chord is only a close approximation of the line of travel.
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Old Aug 13, 2009, 07:47 PM
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OhioMike's Avatar
Grafton, Ohio
Joined Sep 2003
760 Posts
Can we get some servo options with a min of 180 degree rotation, with brand and model numbers? I have plenty of experience with the older airtronics 94581 series of arm winches with a Victor Soling and a marblehead but their long gone and they only had 170 degrees of rotation.Thanks in advance.
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Old Aug 13, 2009, 10:24 PM
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United States, MN, Brainerd
Joined Oct 2004
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Servos for use on larger square rigger models

Servocity.com has an excellent selection of strong servos and robotic servo/gearbox combinations. They have a wide range of power, rotation options, etc etc and their website has excellent documentation and specification info. If you have any questions about an application, you can call them and you actually get very good tech support.
The servos aren't cheap, but I really think (but not sure) that their prices are as good as other internet sites and lower than a hobby shop. (I support buying from the local shop, but the range os specific options, etc and the super tech support/info make servo city my favorite source of specialty servos.)
On each page for the specific servos, look for the little yellow information balloons, eg "How to select a servo" or "how servos work". Great info.

Specific applications:

For a Soling 50, 800 sq in of sail, I use this Robotzone servo/gearbox, with the 3:1 gearing option. I use about 160 deg of rotation for full sail control, but you can order a gearbox with as much max rotation as you need (just call them to work out the options):
http://www.servocity.com/html/spg785a_top_mount.html

For the brig Syren (5ft hull, 12 sq ft sail overall), I use the following servos:

Mainmast and foremast sails, headsails - each uses a HS 785HB servo with 3.5 rotations (programmable to 4 full rotations with a Spektrum) and custom winch drums made from old CD's, etc:
http://www.servocity.com/html/hs-785...rotations.html

For driver sail - HS 805BB with the 180 deg option:
http://www.servocity.com/html/hs-805bb_mega_power.html

For 140deg rotation, there is the 815BB (same as the 805, but with 140 as std rotation). For the same $$'s, I"d get the 805 with 180deg for the extra rotation - why not?
http://www.servocity.com/html/hs-815..._sail_arm.html

Many of their servos can be ordered with either 60, 90, 140 180 and continuous rotation options. And the servo/gearbox "Robotzone" options are almost limitless. They also sell servo arms , drums, gears, chains, etc etc.

Look through the spec tables and pretty soon you get an idea of what's what. Then call tech support for your app and they can zero you in on options.
I know this sounds like a commercial, but they give great service, fast delivery and stand behind their products.
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Old Aug 14, 2009, 07:37 AM
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United States, MN, Brainerd
Joined Oct 2004
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Servos for large square rigger or similar models - part 2

Looking at the SevoCity Robotzone gearboxes, see the following links for what are likely the better servos to use for drum winches.

http://www.servocity.com/html/robotzone_servos.html

http://www.servocity.com/html/tube_s...gearboxes.html

http://www.servocity.com/html/bottom...wer_gearb.html

For use in large sail area models, the above gearbox/servos are likely better than the 785HB's I'm currently using (The 785HB has one ball bearing, a brass bushing, and Karbonite gears.) The above have dual precision ball bearings, hardened SS shaft, precision mil spec pot, optional metal gearbox gears, the servos have metal gears and ball bearings, and the units are rated for 200lbs lateral load. And they are coming soon in a new "square tube" frame design that looks spectacular for secure mounting low in the hull along the keel.

One specific unit has very high torque and 4 full rotations - should be ideal as a drum winch unit:
http://www.servocity.com/html/spg805...-rotation.html
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Old Aug 18, 2009, 03:28 PM
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Brooks's Avatar
Bozeman, Montana, United States
Joined Aug 2003
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Keel Calculation

Keel calculations method (depth and weight needed), post#9
http://www.rcgroups.com/forums/showthread.php?t=1096365
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Old Oct 02, 2009, 09:12 PM
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Brooks's Avatar
Bozeman, Montana, United States
Joined Aug 2003
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Web list of RC squareriggers

Jan Cocatre-Zilgien has compiled a list, with urls, of all the RC squareriggers he can find on the web.

http://www.cocatrez.net/Water/RC_Squ...reRiggers.html

Neville Wade, who has several squarerigger articles in Marine Modelling International magazine, has 2 diagrams of his brace controls and photos of his yard hangers on Jan's website (along with photos of his beautiful models). Scroll down Jan's list till you get to Neville's name.
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Old Oct 29, 2009, 07:28 AM
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United States, MN, Brainerd
Joined Oct 2004
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Request to "stick" this thread.

I requested a sticky for this thread from the moderators. Hope we get it as it's very invisible now...

PLEASE remember to use a TITLE to all posts that includes key searchable words that describe the content. Also, please split separate topics into separate posts.
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Old Oct 30, 2009, 12:04 PM
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Washington State
Joined Sep 2007
239 Posts
Thought I would include this link for technical back ground.
The element and practice of Rigging and Seamanship of 1794 Quit a Bit of information here.

http://www.hnsa.org/doc/steel/index.htm


Very nice Site you have going Dan, I am gonna have to make a set up for making Rope.
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Old Nov 01, 2009, 11:07 AM
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DanL's Avatar
United States, MN, Brainerd
Joined Oct 2004
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Firing guns, Live guns, Carronade - Ignitors and Ignition Device

Ignitors
In building a set of 17 live firing (black powder) carronades for an SC&H Surprise (1/24 scale), the use of commonly available R/C glow plugs as ignitors in each barrel seemed impractical for a number of reasons.
The fine diameter nichrome wire used in the glow plugs is delicate and can burn out easily, gets fouled by the powder residue, is available only in 1.5-2 volt operating range and can be a bit slow to heat and ignite the powder charge. They also cost about $5 each - not inexpensive for a whole set of guns and a replacement supply.
The diagram shows a new design. Only one made and tested so far. Advantages are that heavier wire can be used, sized for the desired operating voltage. The heavier wire is more exposed to the charge, giving more sure and faster ignition. The cost is low, but the brass bolt has to be shortened and then drilled three times - fairly time consuming.
Replacement of the wire is easy. Heater wire, cut to proper length, is crimped into a short piece of 1/16" brass tube. This premade heater element can be inserted into the brass bolt in just a couple of minutes.
Testing will continue to see how these perform over time.
Ignition Device
To fire 17 guns in rapid sequence is also a challenge. Attached is a sketch of a proposed rotary switch. Not yet built. A 360 deg rotation servo, with a Servo Slow attached to control the rotation speed, will make sequential contact to fire the 17 guns in a rolling broadside, perhaps two guns at a time.
Any other ideas for this?
Thanks.
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Old Nov 01, 2009, 11:41 AM
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Brooks's Avatar
Bozeman, Montana, United States
Joined Aug 2003
3,377 Posts
carronade ignition

I used a simpler system, with no insulation of nichrome wire as it ran from electrical contacts thru the barrel. Seemed to work ok. The only problem was if a wire leg touched the other leg prior to the touchhole. Then, the heat would occure at the un-intended junction. As long as I made sure the preformed loop maintained it's loopiness, the system worked.

The nichrome went through the cannon's touchhole, and was blown out when the cannon discharged. The wire was often broken, so I never planned for reuse, just replaced the wire loop.
-----------
You might be able to simplify your design by skipping the insulation. The fire, hot gasses, abrasive ash&unburned powder will erode the insulation, eventually, so getting rid of it would be desireable, I'd think.

One concern - the brass tube crimped to your nichrome will try to exit the area every time you fire. What is your plan for retention...be a shame if you shot your own ship *smiles*. You might have to go to a threaded system if you are depending on silicon insulation forming an interferance fit (due to the erosion).
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Old Nov 01, 2009, 11:41 AM
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United States, MN, Brainerd
Joined Oct 2004
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Ignitor position in Scale guns

From sailing experience with firing guns, max production of smoke seems to be the desired effect. A thiught on ignitor placement and effect on smoke shown in diagram. To be tested.
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Old Nov 02, 2009, 09:38 PM
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United States, VA, Alexandria
Joined Sep 2008
987 Posts
has anyone tried a bottle of propane or similiar, for explosive? You'd need lines going to all the guns, but you wouldn't foul the ignitor. The barrel design might need closing up some to keep the gas in until firing, but everyone here seems to be pretty innovative. Any thoughts?
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Old Nov 02, 2009, 10:17 PM
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United States, MN, Brainerd
Joined Oct 2004
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Propane wouldn't produce smoke. The big effect I've been trying to get is a lot of smoke. Hard plumbing all the lines to hold the pressure seems like it would be a little difficult to do.
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