Model Builder: October 1975

e@ ‘These sails just don’t set right!” “That’s the last time | order sails from him.” These and other complaints are all too familiar to your sailmaker’s ears. In 9 cases out of 10, the fault lies not with the sails, but with the skipper who adjusts them and with the spars they are set upon. Though most owners think that nice setting, strong pulling sails are the responsibility of the sailmaker, the fact is that the best suit ever made can be put upon a crooked spar, and then be even further distorted by mis-adjustment. This column is dedicated to presenting the common faults that are found in sails, with suggestions for their remedy. Many sails will have a combination of faults and will fit in more than one category, so curing their ills will require a series of adjustments. Preliminary adjustments will be made with the boat tipped on its side while ashore. Reeve the necessary downhauls, halyards, outhauls through the sail’s grommets, bend the sail to the spars and begin the process of adjustment. Final Hull is direct relation to famous full size boat. Aside from sail number, can you idantify? By tuning will be made while the boat is actually being sailed. There are two good ROD CARR reasons for this: 1) Only with the sail full of wind will it take the actual shape you should be concerned with… the preliminary state uses gravity to simulate the wind force; 2) By sailing with dif- ferent angles to the wind and the sun, you can view the shadows made by wrinkles, or the shadow cast by the mast on the sails and gain insight into the diagnosis of faults. Sail for a few moments, then return to shore and adjust…one thing at a time. Then back out on the water to see if you have improved things. For an excellent discussion, see Chapter 17 of Jeremy Howard-Williams’ book, SAILS, pub- At times like these. visit your friendly local sailmaker … he’s on your side! Continued on page &1 Fig.1 Fig.2 Fig. 3 % Luff Head = 3 a ~- eK ee. \ ee Foot Tack oe Foot Batten Downhaul Crease 26 MODEL BUILDER NEW \ mr) — ‘ | A ROD FOR ALL Wy SEASONS p—~L\~4\ NEW 8° METAL ROD IS PERFECT FOR THESE NYROD inner tubing “ hd TEMPERATURE COMPENSATED INSTALLATIONS – BEND AS @ N NEC ESSARY § So Stl – POL SIE PRODUCTS = * NYROD outer tubing NEW! 8° METAL ROD them first-hand. The variety of approaches to solving universally problems was astounding. analysis, we are all really some respects, and there is a encountered In the final beginners in great deal to Model Aeroplanes A Splendid Gift Bill Hannan’s Peanul verwon of the “ideal” Nieu- be learned from each other. While there in the sense that we were able to partition, and were able in some small way to strengthen the bond that exists among aeromodellers. We hope that you will all take part again next time, and we’ll do our best to conduct an even better TLELIMOIS €OS464 IS IT A STRUT? IS IT A RUDDER? NO, ITS A STRUDDER! port, Basswood and baisa construction, Wwe cay: were only relatively few prizes, we would like to think we were all winners cipate in a truly international competi- PLAINFIELO SU-PR-KLEVIS ered 1910 NIEUPORT white Complete lyred kit. simulated spoke wheels. plastic prop and thrust bearing, pnniwood, reed, rubber strip and detailed (natruction Manual $449 (§5.00 securely packed and post paid), NJ buyers add $% sales tax Peanul Plan Special Five Peanut Size Kit Plana. WWI and Golden Age Biplanes $1 50 post pard. Scratch Builder Super Offer’ Plan set and printwood for all five models, $5.00 post. pad NJ. buyers add 5% sales tax VINTAGE AERO 20-page Catalog $1 00 DEALER INQUIRIES INVITED contest. VTO CHECKS IN AGAIN World traveller Dave Linstrum, who does such an outstanding job with the free flight column in Mode! Airplane News, is now living in Saudi Arabia, near Dhahran. He reports high winds virtually all of the time (Don’t tell AMA, they might buy it for a “museum”! wen) which forces him to do the majority of his model flying indoors. On the other hand, he certainly has no problem getting fuel to drive to the flying site. Gasoline prices are, believe it or not, only eight cents per galion! e Sailing…… Continued from page 26 lished by John de Graff, Inc., Tuckahoe, New York, | have used this as the basis of our presentation. MAINSAILS The principal faults which are found in mainsails, in order of frequency are: 1. Leech problems: slack, falling away, motor boating, tight. 2. Creases: wrinkles, hard spots, and pleating. 3. Fullness: placement of draft, amount of draft, backwinding. 4. Size: too large or too small. Leech falls away: Halyard needs to VINTAGE AERO 1 THEGLEN @ TENAPFLY. N. J. 07670 to carry a roach which is 40% of the batten length. Classes such as the East Coast 12-meter, which allows a 3 inch roach, but only 5 tnch battens, are especially prone to this problem. The leech will also fall away if the leech has been stretched. In a model yacht, a few 16ths of an inch of stretch is enough to ruin the whole sail. This is why one should always slack off all ten- sions on a sail that is being stored between sailings. The continued tug along the leech will lead to a creep in the fabric. That, along with the breakdown of the resin in the cloth, caused by flogging in heavy air, will produce a sail which is longer from clew to head than when it was built. The third cause of a slack or falling away leech is the simple problem of too much mast bend aloft. Most sail- makers will tell you that the sails are cut for absolutely die-straight masts. Excessive backstay tension, which is not counterbalanced by jenny stay tension, of the sail be set up and the flow drawn forward, tightening the leech. One can sometimes see the entire roach of the sail, from the leading edge of the battens will allow the head of the mast to bow aft, pushing extra cloth into the leech, which slackens and falls away. You will also often see a healthy crease develop from the clew, running somewhat forward toward the middle of the mast combination of a slack leech and a roach which is too large for the battens to carry. Generally, a batten will be able strain the backstay is the reason that some sailmakers will arbitrarily cut a slight S-shaped curve into the mains’ be pulled up snug in order that the luff aft, fold away (Fig. 1). This can be a OCTOBER 1975 somewhere (Fig. 2). This tendency to $2025 FOR MONOS, HY OROS, AND TUNNELS — IDEAL FOR DEEP VEES. ALL ALUMINUM PARTS ARE EXTRUDED HIGH STRENGTH ALLOY, RUDDER BLADE !S STAINLESS STEEL, HORNS ARE GLASS FILLED PLASTIC. FULLY ADJUSTABLE FOR TURN AND STRAIGHT-AWAY TRIM. BRASS WATER PICK-UP (OCWRA) =) wont PO | SUPPLIES TUBE INCLUDED. SEND 25¢ FOR CATALOG ‘OCTURA MODELS P.O. BOX 536 PARK RIDGE, ILLINOIS 60068 luffs. | think it is really trying to compensate for a skippers lack of under- standing of his equipment, and since mast bend varies from boat to boat, one curve will not cure each boat’s pro- blem. Tight leech: The result here is that the wind does not leave the sail parallel to the centerline of the boat, and therefore imparts a rearward component of drive that acts as a brake on the boat. A tight leech can be the result of a sail that ts too full and the attempts to flat- ten it have finally made the leech taut. It can be the result of too much mainsheet tension which has finally removed all the twist that exists between foot WHEN CONTACTING ADVERTISERS, TELL ‘EM MODEL BUILDER SENT YOU! 81 a the TDs and “a N! READY-TO-RUN ELECTRIC-POWERED Jerobee *’Greenwood Vette” W/PROPORTIONAL THROTTLE, DYNAMIC BRAKING, LEXAN CHASSIS, REAR TIRES AND WHEELS “GLUED AND TRUED.” With Futaba FP-2F — Radio System …….. $219.95 With Standard Jerobee Radio System …….. $179.95 Caronly…………. $99.95 Charging cord fits cigarette lighter — recharges in 20 minutes. LEISURE ELECTRONICS 11 Deerspring, Irvine, California 92705 restraining loop of sheet line material ion REMCO 29 _ icnit ENGINE should be fitted around the mast to prevent aftward movement of the tack under the pressure of the wind. Some wrinkles can be the result of too much PRICE $42.50 (engine only) strain having been placed upon the tack grommet, or the result of using too light a cloth for a gusset at the tack. FULLNESS Plus $1.25 for postage and insurance, WIPOURDT” NIU $571.00 Complete -with ignition package (coil, condenser, plug, high tension lead). Plus $1.25 for postage 10 Unless art feat wen. 20 Bo SUNKERS JU 52 ustweme neon ocr en reeud Me 9 FOURNIER AF-S recete SG CLR SPOR oD ded TRO ee, 11 20 QacteasOCe OsOAR ou a Gace an eS to the luff for quite a distance, it may be excessive luff tension which has pulled the draft too far forward. In no case should you have a bolt-roped sail which does not slide easily in the slotted mast. The method and angle of attaching the downhaul may produce creases. Be sure that the downhaul leads away from the tack in a direction opposite to the luff, ie., parallel to the after side of the mast (Fig. 3). Tampa Cut mainsails will often have 4 to 6 inches of bolt rope removed so that the luff of the sail can come out of the slot in order to take on a smooth foot contour. In such cases, an extra ENGINE. Sa MODEL? We need part time sales representatives in practically every part of the country. Show our interesting catalog to hobby dealers in your area, write up his order and mail it in, it’s that simple. With a few calls in your area each week, it is possible to earn enough to offset all your hobby expense. Full time salesmen considered in some areas. For details contact: 82 Sa Ss Seas atattar— l KAVAN MODEL AIRCRAFT, INC. 1432 East Borchard Avenue / Santa Ana, California 92705 / (774) 835-7788 aSSattana fl ed eed Ce eee ed ed ed ed ed aed Coed dd eed ry NEED A NEW RADIO. SSS decided to carry to work in a wide range. As a full enough to give good light air performance. They are then flattened as the wind increases by tightening the foot, using the outhaul, pulling the draft forward as increasing wind pressure blows FE §1 00 dic. design SSS have result, most model yachts sails are made Ao ea REMCO MFG. CO. SSS SS SSS Eee LY an OMmuOn P.O. Box 22414, Denver, Colo. 80222 Creases from Tack: If it runs parallel tet en ee ceo and insurance. are: 1) More tuff tension. 2} Reduce roach. 3) Straighten mast. 4) Reduce foot round (Fig. 2). a6. thet, OS UD Orme © cere te you spare rigs for every 3 to 4 knot change in the wind, your sails will be called upon ALUBBER STOOGE PLANS and head. ft can also be the result of trimming the main boom too near the centerline. The mast shape which has taut jennies will bow forward at the head, this will cause the leech to be strained, and is another reason for recommending that the mast be kept straight under all conditions until you are experienced in tuning. MAINSAIL CREASES Creases trom the clew: Possible cures DEALER INQUIRIES INVITED. it aft by tightening the halyard, and flattening the head by carefully letting the head of the mast bend aft in acontrolled way. As a last resort, the lower shrouds are let go so that backstay ten- sion will throw the Jower third of the mast forward, making it match the luff curve cut in the sail, and returning the cloth to the flat surface it was when it lay on the sailmaker’s cutting table. Such techniques only work in a limited way on paneled or broadseamed sails like the California Cut. Cuts like this, where shape has been built in by shaping the panels, do not have the wide wind range capability that the single panel does, though they may be excellent in their timited velocity span. SIZE Considering the different conditions under which sail area measurement is done; from careful laying out on tables o “eyeball’’ measures done at lakeside, one generally finds that sailmakers will cut the sail from 1 to 2% undersize. This insures that nobody gets ejected from a regatta due to oversized sails, and the area Joss is really minimal when we consider how much unmeasured area is sneaking in under a rule like the 50/ 800 Class. Since the typical skipper does not relax the tensions on his sails after he is done sailing, he starts the year ina windy regatta, stretches his sails out WHEN CONTACTING ADVERTISERS, TELL ’EM MODEL BUILDER SENT YOU! MODEL BUILDER DS$06 RATTLER AA/FD 1/8 SCALE “RAIL” $94.95 12702A N. E. 124TH KIRKLAND, WA. 98033 (206) 827-8606 WE HAVE THE MOST COMPLETE LINE OF 1/8 SCALE CAR KITS COVERING ALL CATEGORIES OF RACING « senccecesvceces C510 READY TO RUN RACER @ We are putting together a limited edition C510 Road Race Kit which includes: @® Futaba 2-channel radio w/FPS-7 servos & steering wheel. @ Sidewinder Veco 19 R/C engine. eFully assembled C510 Road Race Car with painted, trimmed, and mounted Poly- carbonate body, 4 oz. fuel tank, heat sink, and fuel filter. Radio & ‘inkages installed and fully ready to install batteries & fuel and put on the track. e@ This is the same chassis that took 3rd overall at the 1974 ROAR Nationals so you can see you are not buying a noncompetitive product. @ Suggested retail price is only $315.00. e@ For eeeece eevee Choice of Alfa (shown) or Sigma Body Painted and Trimmed. during the next two or three weeks of stressed storage, and spends the season with sails that are just about the maximum allowable dimension, but are somewhat devalued in the shape put there by the sailmaker. In one-design classes, the sails are generally 1% small for the same reason, but every loophole is exploited to get free area, such as the excessive roach mentioned for the East Coast 12-meter class. | would hope that longer battens will eventually be allowed therein. HEADSAILS Basic faults occur with these sails much the same as with mains. The addi- tional problems arise due to, a) the reality that the luff will set upon a stay which will sag to some degree, and, b) that the leech tension will be the result of the jibstay tension acting on a Class | lever with the jib swivel as the fulcrum. The former, stay tension, needs to be maximized in order that decent sail shape will result. A saitmaker will usually cut only a little luff round into a jib since the amount of sag will push extra cloth back into the sail increasing the draft, especially in the middle sections. We have pleaded for easily adjustable jib swivels in order that the lengths of loose. It was then easy to get the wing- and-wing configuration, but a tight leech would be automatically returned when closehauled. The system must work well, since the boat so equipped won the EASTERN 36/00 DIVISIONAL CHAMPIONSHIP this year. So you see, it is really all up to you. The sailmaker has provided you with tension. The distance from the front of the club to the swivel should be directly proportional to wind strength, getting OCTOBER 1975 Le} te ZA | what you need for a good setting suit sary time to adjust them, to get to know them, and above all, to take care of them to avoid stretching and creasing. TRAVELER Ray lhlenburg was nice enough to give us permission to reprint his traveler track design from the Apri! issue of the Richmond MYC Club Newsletter. He has used it on his 50/800 YANKEE and has the advantage that it doesn’t require expensive extrusions and can be made from chunks you find in your junk box. All that is required is some time to insure that it works smoothly and is well attached to the deck. We should have something to say in our next column on the effect travelers have on the performance of the STAR 45. One has been installed to help control the gigantic mains’l on that model, and we will Flat head wood screws: | b- Approx. 1-1/2” 0.C. —el| 2)” Y) Q yale TM Back-up blocks Countersink screw iia SS 063″ Hole for shoot es : _~ Bend to meet deck* – | EF 032″ x 25” Brass _—— Pin and solder (or drill and tap for 0-80) 1” Cleat —+—— These views not to scale is .125″ Brass channel see your hobby of sails. It is your job to take the neces- or nuts & bolts S t{@ the jib club forward and aft of the swivel be chosen to produce the proper leech sity seeetaier Sc information write direct to MRP for our complete catalog. longer as the wind picks up. The jibstay tension not only tightens the leech, it also produces a force which tends to return the jib to the centerline of the boat. This is exactly contrary to what we would like the fib to do when going downwind in light air. The solution has been tried by Ray Ihlenburg, of Richmond, who equipped a HUSON 36 with a backstay which was attached to the sail control unit arm. Upon letting the sails all the way out, the backstay was slackened and the jibstay became rather a more dealer or *Be sure to put traveller on before both ends are bent Trim for eyelet clearance Solder brass channel and .032” x .25″ x .75″ piece WHEN CONTACTING ADVERTISERS, TELL EM MODEL BUILDER SENT YOU! 83 RG’S “Pit Pak” © Transformer Charger ® Rugged Construction ® High Efficiency Roll Pump e Hot Glo-plug Power ® 1.33 Gallon Tank e Nicads Included ® Red, Blue or Green e Tool Caddy A real savings at $39.95 P.O. BOX 406 ST. JOSEPH, MI 49085 Michigan residents add 4% sales tax PHONE (616) 429-3528 ‘HP 61 AFM THROTTLE | WALNUT SCALE FOR MODELS NOT EXCEEDING 18 IN. WINGSPAN just now having with scoring, buoy con- struction, judging, site maintenance, and so on. Nobody will ever benefit if you never mail a copy out of town. With the grumbling | have been hearing from California about the lack of cov- wl (eR nano CO SEND 35¢ FOR NEW 775 CATALOG banal sph (ia af rp 3-color Walnut Scale decals for your erage of their activities in this and other publications, | can only say that the Et Dorado Club is the only one which sends a newsletter my way, and even as big a liar as | am…{1 won’t make up things to say about events and activities which | have no knowledge of. * Next month * * we’ll have reports on the 50/800 ACCR, the AMYA General Meeting and the STAR 45 ACCR. ‘Till then, remember to send your dues into $24.95 e Increases performance for all HPG1F engines e Field tested for three years including 2nd place at 71 and 73 R/C Internats ® New design omits Spray bar providing maximum venturi efficiency I’d like to urge all clubs that have newsletters to take the time to share copies with other clubs, as well as writers like me. The flow of information can be a great help from club to club. Chances are the older clubs (5 yr.) have already found solutions to the problems you are AMYA Secretary, Bud Salika, 3917 Sunnyside Ave., Brookfield, Ill., 60513; it is the best $5.00 you’ll ever spend. And for up to date information on R/C sailing make sure that you subscribe to MODEL BUILDER. Write to me in care of this magazine, or directly to Rod Carr, 7608 Gresham St., Springfield, Va. 22151. e e Super free throttle barrel movement AVAILABLE AT YOUR FAVORITE DEALER Av) NELSON MODEL PRODUCTS : ft 6929 WEST 59TH STREET CHICAGO, ILLINOIS 60638 « (312) 566-7101 test it in the ACCR to make sure we have a good trial. CLUB NEWS \’m happy to note the birth of yet another AMYA Sanctioned Club. The Yn, JOIN THE AMERICAN MODEL YACHTING ASSOCIATION SEND $5.00,YOUR NAME AND ADDRESS TO BUD SALIKA,3917 SUNNYSIDE AVE. BROOKFIELD,ILLINOIS 60513 INDY R/C Model Yacht Club has already held its first regatta. You may contact Ted Brindle, 8338 East 36th Street, Indianapolis, Indiana 46226, for further information on club activities, classes sailed and so on. I’m also informed that a club may be forming in the Charleston, West Vir- ginia area. If you are interested, drop a note or call John Niedermeyer, 3 Peyton Avenue, St. Albans, W.Va. 25177. 84 WHEN CONTACTING ADVERTISERS, TELL ‘EM MODEL BUILDER SENT YOU! MODEL BUILDER