Dec 27, 2012, 07:02 PM Registered User United States, MN, Brainerd Joined Oct 2004 2,488 Posts Brace slack "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." I completely agree with the two characterizations of sources of brace slack. The sliding servo actually does correct for both. It surprised me when I first did a layout on the floor to test the concept almost two years ago. We discussed it all at that time (old posts are somewhere...) Again, I was surprised and just couldn't figure out how it worked. This is what I think is happening, both then on the floor and now with the two "sleds" installed and operating in Syren. ( Note that some bungee is still used, but only on the topsail yard to compensate for the geometry difference and imperfect drum diameter sizing differential between it and the course yard. There is also the geometry difference due to the vertical angle of pull - almost level braces for the course and vertically angled for the topsail. I've done the geometry - chords, angular pull, etc. It can actually work to advantage to get "spiralled" yards. Also posted in the past...) I'm off on a tangent now....(pun intended). Back to sled observation.... For squared vs fully braced slack differential, it's easy enough to see the sled slide against the springs as the yard is squared. As the yard is braced over (forgive my probably inaccurate terminology), the sled slides back, pushed by the springs. Both braces stay taught. As the servo drum turns to fully braced, both braces are still taught. If I program the Tx travel to try to rotate the yard beyond the maximum, the unpulled brace does start to go slack when the servo pulling force exceeds the force of the springs. You can see the sled now move forward against the springs. The drum rotates a bit, the pulled brace stays very taught, and slack appears in the unpulled brace. I think the reason the sled corrects for both conceptual explanations of slack is that as the drum rotates, say one unit, it should pull in one unit of brace AND should let out one unit of brace. I say "should" because the drum doesn't ever get to one unit of rotation - the sled movement provides a portion of that one unit of brace length change. It's hard to explain, and even hard to see on the model, but it can be seen. The spring force - energy stored by the rotation of the servo - interacts with the servo force/rotation to balance the forces and movement of the braces. Bottom line, by observation, until the drum pulling force exceeds the counterforce of the spring (due to too weak a spring or a yard run hard against an obstruction), the sled will address both types of slack. (Philosophical thought - how would the sled "know" which source, "a" or "b", were causing slack. It simply balances rotational force of the servo and linear force of the springs to take up any brace slack. If it addresses any slack at all, it must address both types - it can't differentiate source of slack) My usual disclaimer - "I'm often wrong, but never unsure." Peace and all the best in the New Year to all. The Slack Not Taken with apologies to Robert Frost Two braces diverged from a yard of wood And sorry servo could not ravel both And be one servo, long it stood Then pulled on one as far as could To where it stopped, not due to sloth. Then pulled the other, as just as fair, And having perhaps the better claim Because it was slacky and wanted care, Though as for that the pulling there Had tightened them really about the same, Last edited by DanL; Dec 27, 2012 at 07:54 PM. Reason: added poem
 Dec 27, 2012, 11:30 PM Damp and Dizzy member Bozeman, Montana, United States Joined Aug 2003 3,495 Posts Great poem :-)
Dec 28, 2012, 05:18 PM
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An explanation of brace slack control by sliding servo

OK - hard to conceptualize, so I did a floor model and took pics.
The geometry matches the dimensions of the Syren forecourse yard. The floor model drum is almost exactly the diameter of the Syren drum.

Pic A: The yard is squared
Servo is at zero rotation
Both braces taught and total brace length is at a minimum.
The servo is at 24" from point of yard rotation
This position represents the "sled" being fully forward against the springs

Pic B: The yard is rotated to 60deg (a bit beyond the 50+ on Syren)
Servo has rotated exactly 1.5 turns
Unpulled brace develops high slack
The servo is held stationary at the original 24"
This servo position represents a typical stationary servo

Pic C: The yard is rotated to 60deg (exactly as in "B")
Servo has rotated about 1.37 turns (1-3/8 turns)
Unpulled brace develops no slack
The servo has moved 1.5" back to 25.5" from point of rotation
The servo sled travel has both taken up slack AND also contributed to
some of the pull length of the pulled brace, as the drum has had

The spring loaded servo can move non-linearly in combination with rotation of the drum. Since the servo is also moving, the rotation of the drum no longer has a linear relationship to the length of brace released/pulled. As long as the yard rotates with somewhat balanced side-to-side force, the sliding servo action and rotating drum action will autonmatically somewhat balance the tension on both braces, hence little to no slack.

Hope that clarifies it. It's cool to see in action.

Forewarned - it's not perfect. Unless the spring tension always exactly compensates for the servo pulling force, unbalanced tension in the braces can develop. I'm using springs - yhey are not a perfect match over full travel. That's why I may yet experiment with adjustable bungees. But the system on Syren does work almost perfectly. Video soon if desired.

# Images

 Dec 29, 2012, 10:09 AM Damp and Dizzy member Bozeman, Montana, United States Joined Aug 2003 3,495 Posts Great photos, and a logical explanation of what's happening. Thanks, Dan. On a real square-rigger, the spring could be replaced by a hydraulic cylinder controlled by a strain gauge. You have invented a patentable machine. Your dated posts would serve a proof of primacy. You'd have to ask a patent lawyer about the public nature of your reveal, but I am guessing that would not pose a fatal problem to your application. Scientific papers reveal patentable information before the patent is granted all the time.
 Dec 29, 2012, 10:30 AM Registered User los angeles Joined Jan 2009 152 Posts That's what I said. It is so cool and so innovative, it SHOULD be pattented. If Dan is so generous, he can allow free use to the modelers, but charge licence fees for commercial use. I bet a company like ServiCity might be interested in producing a square sail sliding winch.
 Dec 29, 2012, 01:28 PM Damp and Dizzy member Bozeman, Montana, United States Joined Aug 2003 3,495 Posts The way patents work is that anyone can use the method for personal purposes, no permission or payment necessary. Only when you want to charge others \$ do you have to get patentee's permission (and probably buy a licence). This quirk is one reason drug companies don't often patent their discoveries - anyone is free to use it, the patent reveals exactly how the drug is manufactured, and, of course, the published patent opens the door wide to pirates in the 3rd world (where foreign patents are not well protected by local courts). We all know that Dan is not a grinch (by his willingness to help others here on the forum), so even if patent law were different, I bet he'd still let us use his invention for free on our own boats. Now, if you are building model boats to sell to others, then it's a different story, of course. A Dan patent would be the tool to demand payment for use of his invention. -------------- Patmat has several patents. Ford's attorneys probably did the paperwork, but Pat would be a source of advice from someone who's actually gone through the process. Last edited by Brooks; Dec 29, 2012 at 01:52 PM.
 Dec 29, 2012, 02:02 PM Registered User United States, MN, Brainerd Joined Oct 2004 2,488 Posts Wow. Thanks very much for the interest. I worked for over thirty years in R&D, have patents and am familiar with them. This won't be patented - at least not by me. The idea was put in the public domain over two years ago in a number of posts I made in one of the threads here. And I think similar ideas were posted by others. I haven't done a search, but I'll bet a similar system has been posted on a ship model website somewhere. That pretty much makes it ineligible for a patent. Also, it can likely be found "not novel", as spring loaded shuttle systems for controlling thread tension exist in the weaving/looming industry. And patents end up costing a lot of money, with low likelihood of ever getting any financial return. And they cost a ton to defend if challenged or infringed. Anyway, it's a hobby, it's fun and that's how I want to keep it. If this rigging method helps RC boat modelers, that's great. Go for it.
 Dec 29, 2012, 02:10 PM Damp and Dizzy member Bozeman, Montana, United States Joined Aug 2003 3,495 Posts Your decision, of course, and you are speaking from experience. Since you already hold patents, I guess you don't need this one for the ultimate Geek Medal of Superior Honor :-) I think the 2 year lag between reveal and application would not be insurmountable: "I did not realize this was unique. I wanted to confirm certain aspects of the invention. I did not have funds to pursue a patent at that time. etc." Unless someone else has already patented your idea, I think you would still have a valid claim. Many microbiologists had seen their cultures die due to "contamination",and it was widely reported/known in the microbiology world. It took Fleming to realize that penicillin, the contaminate, could be used to save human lives. As far as similarities to the loom industry, well, Amazon or someone patented the Internet "shopping cart" idea, and real shopping carts have been around as long as the wheel. Just because something exists in one industry does not seem to prohibit the same idea being patentable in another industry. Just because wheels existed on oxcarts does not prohibit Ford from patenting modifications to "my wheels" :-)) I've been looking at a lot of squarerigger models over the years (since around 1980). I've never seen this method of controlling slack. I know it's never been used on a real squarerigger - Jarvis winches are the only ones ever to go to sea, and they were not a perfect success. There is a website where the owner has tried to post a url for every RC squarerigger; I've looked at them all, about 50 or so. I think if this method were already known, it would have showed up there. ------------ For anyone else interested in patents, there is a "provisional application" process in the US. You file a simplified description and gain a 12 month window to complete the application. Cost in 2011 was \$125, according to Wikipedia. This gives you time to work up the formal application, seek legal help, etc. I think it's the basis for the "pat. pending" terminology you often see. -------------- At any rate, Dan you've accomplished something that has been sought for as long as there have been squareriggers, Well Done! http://en.wikipedia.org/wiki/Provisional_application http://www.uspto.gov/patents/resourc...es/provapp.jsp Last edited by Brooks; Dec 29, 2012 at 02:35 PM.
Dec 30, 2012, 12:03 PM
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New carronade barrel design and laoding method

An improved carronade igniter design was discussed a couple of posts back:
http://www.rcgroups.com/forums/showp...&postcount=178

More details in the attachment on the mod's and on a new loading technique for use with an igniter placed at the muzzle.

The doc is a collection of modified old and new drawings and description of mod's.