May 2006 Vol. 23, No. 5 - RC Soaring Digest

May 2006Vol. 23, No. 5

CONTENTSMay 2006Vol. 23, No. 53 In the Air!RC Soaring Digest Editorial.4 Blackie the EagleEvan Shaw designed, built, and flew a radio controlled bird —a full size model of a South African Black Eagle. By Evan Shaw9 Harley Michaelis’ Genie, Part 3 - Rudder, stabs, carving.The construction of a Genie continues. In this installment,the open-frame rudder and stabilizers are built and thefuselage is finished. By Chris Boultinghouse21 Maple Leaf Design Encore RC-HLG, Part 3Phil Pearson presents the second in a series of articles thatprovide a text and pictorial walk-through of the entire Encorekit production process. By Phil Pearson29 Peter Wick on Planks - Part 5The fifth in a series of articles devoted to the aerodynamicsand design of “planks” - tailless aircraft which are easy to buildand can really perform on the slope and over flat land as well.By Peter WickFront Cover — Charl Viviers launches Evan Shaw’s “full scale” BlackEagle at the annual Black Eagle Slope Weekend on Tamatiebergnear Volksrust, South Africa. http://www.f3x.za.org/gallery/BlackEagle2006/black eagle2006.php Photo by James Shaw.Canon PowerShot A70, 1/1000 sec, f 5.0 at 5.4 mm.The Natural Side of Thermal Soaring: A review of the 32Secrets of Thermal Soaring DVD by Radio Carbon ArtPaul Naton’s weather-related DVD is reviewed by the RCSDthermal soaring columnist. By Lee MurrayGordy’s Travels: Supra - the latest “Silver Bullet” 34The recent entry from Kennedy Composites. By Gordy StahlNotes on the Supra #16By Dave Corven 36Modifying the Rotary Drive System (RDS) 37How to adapt the RDS to specific applications, from RC-HLGto large TD ‘ships. By Winston OkerlundChris Erikson’s Wild Arsed Mountain Slopers (sans Chris) on 42(usually) scenic Saddle Mountain, April 8-9, 2006Typical Northwest Spring rain and wind don’t dissuade theseintrepid adventurers one bit. By Philip RandolphJeret Lemontt and Don Thuren fly their Weasel-pros 49at The Ruins, Santa Barbara, California. Photo by Steve LangeBrian Kloft’s Alula 50Brian bought an Alula kit after getting home from Seattle lastyear. Here’s the story on how he finished the airframe andhow he protects his sailplane when he travels. By Brian KloftBack Cover: Gordy Stahl doing some DSing with his SageCompulsion at Frankfort, Kentucky. Photo by BruceDavidson. This image was originally used on the front cover ofthe June 2004 issue of RCSD, but was presented in a verticalformat which greatly reduced its size and visual impact.

R/C Soaring DigestManaging Editors, ctChris BoultinghouseJay DeckerLee MurrayTom NagelMark NankivilDave RegisterJerry SlatesGordy StahlPeter WickDon BaileyGregory CiurpitaDave GarwoodBrian KloftPhil PearsonDave GarwoodDave BeardsleyMark Nankivilrcsdigest@themacisp.netWeb: http://www.rcsoaringdigest.comYahoo! group: RCSoaringDigestAIM screen name: RCSDigestR/C Soaring Digest (RCSD) is a reader-written monthlypublication for the R/C sailplane enthusiast and has beenpublished since January 1984. It is dedicated to sharingtechnical and educational information. All materialcontributed must be exclusive and original and not infringeupon the copyrights of others. It is the policy of RCSD toprovide accurate information. Please let us know of any errorthat significantly affects the meaning of a story. Because weencourage new ideas, the content of each article is the opinionof the author and may not necessarily reflect those of RCSD.We encourage anyone who wishes to obtain additionalinformation to contact the author.Copyright 2006 R/C Soaring DigestPublished by B2Streamlines http://www.b2streamlines.com All rights reservedMay 2006In the Air!B2 KuhlmanYou are now reading one of the largest issues of RC SoaringDigest ever published. This is an incredible milestone, giventhat until recently a portion of the magazine was devoted toadvertising.Producing a PDF this large is not at all difficult or time consumingonce the magazine layout is completed, but the produced file willalways be sizable, and readers without access to broadbandinternet will spend a lot of time downloading the PDF.For this reason, a compressed PDF, roughly half the size of theoriginal, of this and all future issues will be available to membersof the RCSoaringDigest Yahoo! group within the Files section.These compressed PDFs lack the high image quality of theoriginal, but are substantially quicker to download for those withdial-up access only. The February, March, and April 2006 issuesare already posted in the Files section.While there’s a daily download volume limit for Yahoo! files, andyou may have to wait for a restriction to lift before downloading acompressed issue, the PDFs will remain available for about fourmonths after publication.You must be an RCSoaringDigest group member to access theFiles section. If you’re not a member of the RCSoaringDigestYahoo! group, it’s free and easy to sign up. Go to the RCSD homepage, enter your e-mail address in the blank below where it says“Subscribe to RCSoaringDigest,” and click the Yahoo! GroupsJoin Now! button.Our sincere thanks to everyone who contributed to this issue!We had a grand time putting everything together.Time to build another sailplane!3

Blackie the Eagleby Evan Shaw, evshaw@telkomsa.net James ShawThis composite photo shows Charl Viviers launching the Black Eagle during the Black Eagle Slope Weekend at Volksrust, South Africa.4R/C Soaring Digest

Phase 1: The idea, the design, thebuilding and setting upOriginally, I started the project of buildingthe Black Eagle because of the “Black EagleSlope Weekend” that I organize each year.I was going to build it with conventionalailerons/drag flaps with cheater fins, etc.,as I had seen in old magazines. Then afriend of mine sent me an article from theJune 2002 issue of Model Airplane Newsmagazine about a Turkey Vulture that BobHoey had built using wingtip aileronfeathers, as he calls them, so I decided totry that method.Basically what happens is that the firstthree wingtip feathers rotate around alongitudinal axis and these act like aileronscausing a turn. According to Bob Hoey it isthe most bird like of the directional controlmethods that he has tried on “model”birds. I won't go into the nitty-gritty ofhow they work here. Perhaps we could getBob to do an article on them some time.I built the model out of foam and glass.The fuselage is a plywood box, in which Iput the receiver and batteries, with foamglued to it, and then sanded to shape andcovered with glass cloth and painted.The stab is a balsa built-up frame coveredwith Solofilm, and the elevator is actuatedby torque rod, so no control rods are seenMay 2006on the outside. I made up the connector tothe servo myself by soldering a brass stripto one of those brass thingies from anelectrical “chocolate block” and thenscrewed it to a servo output arm.The wing itself was made up in ninesections and cut using a total of 12templates. The section is the MH46 at theroot and MH49 at the tip. Once cut, thesections were then glued together andblocked up on scrap foam to create theclassic dihedral/anhedral shape that Iwanted.I installed the servo for the wingtipfeathers right at the tip before I bagged thewing. Not the best option, I know, as itcompletely encapsulates the servo. If oneneeds to do repairs, then it is definitelygoing to be a problem. But I wanted astrong, lightweight method, so I figuredthat I would take the chance that I won'tneed to be doing any repairs to the servo. Iused the small Hitec HS55 servos.I had serious reservations about how thewing was going to turn out with all thoseangles and contours of the rather thickreflexed sections. I spent several hourscutting and fitting the Mylar sheets to thefoam so it could take all the shapes, andspent a lot of time aligning the core intothe outers while in the bag.I was extremely happy with the final resultonce it came out of the bag and I hadfinished trimming all the bits and pieces.The total span with feathers is 1500mmwith a wing area of about 27sqdm andweight of about 950grams when balanced.I used my normal bagging technique, withcarbon tows glued to the leading edge. Theend result is a very strong and lightweightwing.The wingtip feathers are made from 2mmbalsa, as suggested by Bob Hoey in hisarticle. I am not very happy with them, asthey seem to be very flimsy and break tooeasily for my liking, so I will be making upa set of carbon ones soon.To determine the CG location, I used therule of thumb of 1/6th MAC that hasserved me well for all of my flying wings.Of course this may change a bit after moreflight tests have been performed, but onthe initial flights it seemed spot on.The program I use calculate the MeanAerodynamic Chord is one that Idownloaded from http://www.jean-claude.etiemble.com/tracfoil/ years ago and it makes finding the MAC ona multi taper wing a doddle. It’s freewareand the link still works.5

Upper left: The major parts completed, ready for finishing and final assembly. Right: Evan trimming the wing. Lower left: The specially builtfixture that connects the servo output shaft to the elevator torque rod. Right: The stabilizer and elevator assembly, prior to balsa sheeting.6R/C Soaring Digest

Left: All that’s lacking is a bit of paint. This view shows the tip feathersvery well. Note the change in angle from the first to the last feather. Thefirst three are mounted to a single balsa block and are rotated in unisonby an HS-55 servo.Below: Painted and ready to fly! The size and color scheme preciselymatch those of the South African Black Eagle (Aquila verreauxii).See http://www.joburg.org.za/2005/jul/jul21 chicks.stm and http://www.worldbirder.com/photo/thumbs.asp?SID 785 .May 20067