r/c soaring digest - aug 2003

August 2003

August, 2003Vol. 20, No. 8

U.S.A. $3.50

R/C Soaring Digest

ABOUT RCSD

R/C Soaring Digest (RCSD) is a reader-written monthly publication for the R/C

sailplane enthusiast and has been publishedsince January, 1984. It is dedicated to sharingtechnical and educational information. Allmaterial contributed must be exclusive andoriginal and not infringe upon the copyrightsof others. It is the policy of RCSD to provideaccurate information. Please let us know ofany error that significantly affects themeaning of a story. Because we encouragenew ideas, the content of all articles, modeldesigns, press & news releases, etc., are theopinion of the author and may notnecessarily reflect those of RCSD. Weencourage anyone who wishes to obtainadditional information to contact the author.RCSD was founded by Jim Gray, lecturerand technical consultant.

RCSD should not be considered to endorseany advertised products or messagespertaining hereto. An advertising rate card isavailable for businesses, and clubs.

Feature ColumnistsBill & Bunny Kuhlman (B2),

Lee Murray, Tom Nagel, Mark Nankivil,Dave Register, Steve Savoie, Jerry Slates,

Greg Smith, Gordy Stahl

ArtworkGene Zika is the graphic artist

who designs the unique ZIKA clip art.

RCSD StaffJerry Slates - Editor/Technical EditorJudy Slates - Managing Editor, SubscriptionsLee Murray - RCSD Index/Database

(available on-line)Bill & Bunny Kuhlman - RCSD Web Masters

PayPal Coordinators

Copyright © 2003 R/C Soaring Digest.All rights reserved.

R/C Soaring Digest556 Funston Drive

Santa Rosa, CA 95407phone: (707) 578-7871

e-mail: [email protected]://www.b2streamlines.com/RCSD.html

OTHER GOOD STUFF

19 Classified Ads - New Products15 Schedule of Special Events

Monthly Feature Photography & Web Version of the Printed Article (where appropriate)Highlights & Mailing Status of the Current IssueAbout RCSD..................................................................................... Subscription Information...................................................Advertising Rate Card (Adobe Acrobat PDF format).............................................RCSD Feature Columnists, Reporters, and Editors....................... (E-mail/web addresses, plus general information about their areas of interest)"Getting Started in RC Soaring" ........ Getting started guide - Adobe Acrobat PDF formatLinks to Organizations, Special Interest Groups & ClubsOn-Line Articles - Great articles originally written for the printed version of RCSD......................................... "Trimming Your Sailplane for Optimum Performance" by Brian Agnew.................................................................................................. "Flys Faster" by Dr. Michael Selig.............................. "The Square-Cube Law and Scaling for RC Sailplanes" by Dr. Michael Selig.................................. "Modifying & Building the MB Raven (Parts 1-4)" by Bill & Bunny Kuhlman............................................................. "Butterfly and Moth Airbrushing Tutorial" by Joedy DruliaBookshelf Listings - A listing of recently published books of interest to aeromodelers.Complete RCSD Index, 1984-2002

RCSD ON THE WEBhttp://www.b2streamlines.com/RCSD.html

TABLE OF CONTENTS

3 "Soaring Site" ....................................................................................... Judy SlatesEditorial ........................................................................................ LSF Board of Directors Election

4 Scaling Methods ................................................................................ Rense Lange............... Model Sailplane Competition: From Awarding Points to Measuring Performance Skills

12 "Tech Topics" ................................................................................... Dave RegisterTechnical Analysis & Design ...................................................................Polecat Aero's XP3 DLG

16 Servo Design ...........................................................................Bill & Bunny Kuhlman.................................................................................... Modifying a Servo for Reversed Operation

15 Cavazos Sailplane Design17 R/C Soaring Digest

Special Interest Groups19 Eastern Soaring League (ESL)19 International Scale Soaring Assoc.19 League of Silent Flight19 Sailplane Homebuilders Association19 T.W.I.T.T.19 Vintage Sailplane Association

Advertiser Index

Events18 Last Fling of Summer - OK

Don't forget to check out the RCSD web pages each month.Cover photographs are always available for viewing, and

usually available for downloading, as well. Special article .pdf filesare frequently available for a limited time, and of course our webmasters update the highlights and status information of each issueas it becomes available.

August 2003

TheSoaring

Site

Back Cover

ELMIRA 1997

Elmira Aero Tow event.

Photography by DaveGarwood, New York.

Elmira 1999

Elmira Aero Tow event.

Photography by DaveGarwood, New York.

LSF Board of Directors Election

We received an e-mail from Mike Glasswith the Soaring League of North Texas.Mike had received what follows fromHenry Bostick who asked that he send it totheir e-mail group. Many of you are likelyinterested in this subject, as well.

Henry said, “Mike, I have known thesefellow flyers for a number of years andbelieve they would be an excellentslate for any flying organization.Would you be so kind and forwardthis to our club e-mail list. The LSF is amajor SIG working with the AMA,giving direction and guidance to R/CSoaring, and most especially theNational Championship in Muncie.”

— Forwarded by Tom Kallevang/IT/SEARS on 08/22/2003 09:00 AM —

“Hello, all. I’m sending this note toyou because I and several others areinterested in running for the LSF Boardof Directors during this election cycleand we are soliciting nominations forour slate.

“I am running for the office of Presi-dent, Martin Doney of Baldwin,Michigan is running for Vice Presidentand Larry Jolly is running for Trea-surer. We are not running a Secretarynominee as Jim Deck is the incumbentand will be finishing off his term thatwas interrupted by his illness. Jim’sexperience brings continuity to thenew Board.

“The information you need to providein a nomination is the following:President: Tom Kallevang LSF #303Vice Pres: Martin Doney LSF #7429Treasurer: Larry Jolly LSF #3579

“Right now, only mail-in nominationsare being accepted, although the onlinepage at the LSF web site should beactive soon.

“Here is the URL for the nominationweb page: http://www.silentflight.org/vote/vote.shtml

“There is confusion about whether you

must contact the LSF once every twoyears to be considered an “active”member. In previous elections, theentire LSF membership exceptingaspirants were allowed to vote. Becauseof some outdated verbiage in the By-Laws that was designed to help keepthe mailing costs of LSF newsletterscontained, some people feel that onlythose contacting LSF within the last twoyears (this includes upgrades in levels)are “active” members.

“A Level 4 or 5 is considered activeregardless if there has been communica-tion or not. RCSE posts by othersindicate that you must contact Jim Deckwith your current information (name,address, LSF #) so he may update thedatabase. That’s a good idea in any case,since the LSF should know where itsmembers are located.

“You can send Jim an e-mail at this address:<[email protected]>. Please includeyour name, address and LSF #.

“Larry, Marty and I hope we can count onyour support to win our way into theelection via your nominations. If you feel weare the right people to advance the sport andyour interests, then please exercise your LSFmembership rights and nominate us for thenext Board of Directors.

“Please feel free to share this informa-tion with other LSF friends that I maynot have had an e-mail address for.

“We should have a web site that givesbasic bio and position statementsavailable soon. Keep watching RCSE formore developments.

“Thanks in advance for your support. Withyour help, we can continue the evolution ofour sport and our organization.”

(signed) Tom KallevangMember of SOAR (Chicago, IL)AMA 8293 (Contest Director of the

annual SOAR FRED contest)LSF #303, Level V #103

Happy Flying!Judy Slates

R/C Soaring Digest

August 2003

R/C Soaring Digest

August 2003

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August 2003

R/C Soaring Digest

The completed XP3 DLG model out on thefront lawn. It’s 100+ these days so not toomuch fun to go out and get flight shots.

Dave RegisterBartlesville, Oklahoma

[email protected]

TECH TOPICS

Alittle while ago one of DennyMaize’s XP3 kits showed up at the

house. Upon opening the box, a reallyserious round of cussing and carryingon ensued. Cats dove under couches.Paint peeled off the walls. Waterboiled in the pipes.

After regaining some composure I hadto admit there was just no way I couldever come close to the quality of thiskit. You try and take pride in your ownworkmanship but when you’re out-done this badly it really hurts. It’ssimply the highest quality kit I’ve everhad the opportunity to own.

With the fires somewhat ebbed, let’slook at the details of this very welldone DLG. As readers of “TechTopics” recall, we’ve had a good timeanalyzing HLG’s and DLG’s recently.Mark Drela’s X-Foil has been used toanalyze airfoils. A Visual Basic pro-gram was written to estimate launchconditions. Other analyses were doneto estimate performance, wing loadingand optimized planforms.

The bottom line is that if I wanted todesign something to meet all thecriteria evaluated, it came out lookingan awful lot like an XP3. After a coupleof e-mails to Denny, a flaperon XP3was on the way.

Sorting through the box you’ll find aKevlar fuselage with a carbon boom,two of the most gorgeous DLG winghalves you’re ever going to see, andhorizontal and vertical balsa stabs thatare faced with light glass fabric. Theappropriate hardware is supplied formounting the wings and horizontalstab. Several control linkage optionsare also included.

You’ll find the instructions on thePolecat Aero web site along withseveral articles on set up, flying andtrim all in PDF format. This is a greatway to do it since the latest updatesare always available to everyone.

You supply the wing wiring harness

but you will probably choose special-ized servos for the wing so yourwiring will be particular to yourinstallation. The channel for theharness is nicely drilled out and theservo wells were perfect. Instructionsfor drilling the peg position and angleare covered on Denny’s web site. Thereare streamlined pegs now available sothe choice of launching peg is up toyou.

Although the parts count is low, somecare and preparation should be takenbefore getting into this project. Thefirst thing is downloading and printingthe assembly instructions. Then readthem over several times and visualizeall the assembly details.

For instance, notice that the mountingbracket for the horizontal stab fitsproperly in only one direction. Thetaper is subtle but important. If thestab doesn’t clear the vertical fin,you’ve got it on backwards! Do thisassembly dry and then mark theproper end of the fixture for later use(guess who almost got this wrong?).

Next thing to consider is your choice ofequipment. Micro servos of the S90,HS50/55 JR241 and similar variety areappropriate for the rudder and eleva-tor. Probably something on the 15 to 24in-oz torque range would be appropri-ate (high end for the rudder). If you’vegot the poly version, that covers it. Ifnot, read on.

The wing uses Drela airfoils and isquite thin in the servo area. If yourservo is over ~9mm thick it willprotrude a bit. There are only a veryfew models that fit completely in thewing. The JR241 appears to be thepreferred wing servo and at a bit over10mm it will protrude slightly.

I ordered PS30s from FMA for thisproject. They are 9mm thick and have12 in-oz of torque at 4.8V. They fitperfectly in the existing servo wellsand were exactly flush with the winglower surface. The other servo that fits

POLECAT AERO’S XP3 DLG

completely in the well is the Dymond60. Randy McCleave speaks highly ofthese and I have a set of them on order.

Also check out your battery, Rx andgyro needs before you get started. Iwound up with a 110maH NiCd packin the nose followed by the gyro andservos under the canopy and a FMAM5 receiver under the wing butjammed up against the rear of theservos. You may want to use adhesivetape for anything not nailed down. Thelaunch forces can get to be many 10’sof G’s so things will move if given achance.

A NiMh pack (AP 200 square packstyle AAAA battery sizes) fromBatteries America will also work(200maH). Denny makes his own packfrom 280maH NiMhs.

Most everything you need to know forassembly is covered by the instruc-tions. I’ll just highlight one or twothings.

I would recommend setting up thewing peg hole prior to joining thewings. Setting the angle is a lot harderwith 60 inches of wing hanging offyour drill press. To set the angle, I tookhalf the total dihedral angle, set that onthe drill press base and worked myway up on drill sizes. Glass, Kevlar

August 2003

Stabilizer Detail - Z-Bends and BalsaSupport for Rudder Linkage.

All That’s Going in Here? HS55 servos,Gyro, FMA M5 Rx and 200mah NiMh pack.

Yup, it All Fits! NiMh Pack SLidesCompletely Into the Nose.

and foam don’t drill real clean so don’thit it with the final size first. I prefer totake it in two steps with the final hole afew thou under the final dimensions soassembly is very tight prior to gluingin the peg.

Joining the wing halves worked fine.Choose the dihedral angle that worksbest for you and then epoxy as di-rected. I had some misgivings aboutthe filled epoxy for the wing bolts.They seem to be OK now but they hada little give after 24 hour cure. I addeda 1/64" ply cap over each bolt hole.

After tapping the holes in the ply wingsaddle for the wing bolts, hit themwith thin CA. Let that set and then tapagain. Repeat a couple of times untilyou’ve got very hard but accuratethreads in the wood base.

Splooging the wing saddle is a highlytechnical term Denny uses for globbingup the gaps in the wing saddle withfilled epoxy. Sand and clean the wingsaddle first to remove any releaseagent. Then cover the bottom of thewing with Saran. Use tape at strategicpoints to stretch it out smooth in thecontact area. Apply some wax orVaseline to the nylon bolts. Mask thefuselage sides around the saddle withtape so the overrun peels off easily.Then mix up a ketchup like consis-tency of micro balloons in 30 minuteepoxy, slather it on the saddle, bolt onthe wing and go have a couple ofbeers.

With the wing mounted, you can nowaccurately glue on the horizontal stabfixture. Mount the stab (get the rightend forward!) and eyeball the stab tobe properly aligned with the wing. Besure you sand the boom under thisfixture so the glue will grab well. Onceyou’ve got the alignment right, hit thefixture with CA and then LEAVE ITALONE FOR ABOUT 15 MINUTES.CA sometimes does not fire off imme-diately on some carbon surfaces. Addthe adhesive carefully and then backaway from the airplane. Perhapsanother beer is called for here.

After the horizontal stab is set, notchthe vertical stab for the boom taper. Ifyou’ve done this right, the vertical stabhas a slight friction fit to the boom soyou can set it properly and not have tosupport it with an external fixturewhile the CA grabs it. Use a right angle

R/C Soaring Digest

to be sure you’ve got the vertical ANDhorizontal alignment just where youwant it. Then hit the contact area withthin CA and again leave this alone forabout 15 minutes.

As per the instructions, you’re going toCA glass fabric reinforcement on thevertical stab so the initial glue jointdoes not have to be massive. Oh yeah,you did round off the leading edge ofthe stabs before getting to this pointdidn’t you?

Linkage is up to the builder. There areinstructions for running a pull-pullsystem. There’s also Teflon tubing andwire for running a stainless steelpushrod system as used by Mark Drela(~ 0.014" wire). There’s some largerdiameter tubing for running a 0.020"carbon pushrod system as well (sup-plied in the kit).

My choice for linkage is 0.055" z-bendmusic wire for flaperons (supplied)and 0.020" music wire for the stabiliz-ers (not supplied in lieu of the carbonrods). The stab linkage uses the largerdiameter tubing (yellow supplied withkit). Although I love to fly DLG, at myage I’ll never be competitive so I optfor something a bit more robust andreliable.

I used the supplied 3/32" ply horns forthe flaperons but made my own 1/16"ply horns for the stabs. The longer stabhorns still provide plenty of travel butminimize the effect of play in thelinkage or servo gears.

The linkage tubing for the stabs isrouted through a small opening at thebase of the wing saddle and then tackglued with Goop along the carbonboom. A third tube is also used in thislocation for the Rx antenna to exit thefuselage.

The connections at the stabs are z-bends. This allows the horizontal stabto be easily removed. I use nylon mini-clevises at the servo end for all link-ages (not supplied).

At this point, adjust your throws andtrims as per the instructions. As withany high performance ship, there aremany ways to set it up. The instruc-tions on the Polecat Aero web site arean excellent basis for configuring anXP3. Mark Drela’s article also providesvery valuable suggestions for trim-

ming and launch set up. For me, a gyrois a must. I prefer the near instanta-neous response of the gyro duringthose first few fractions of a secondafter launch.

FLYING THE XP-3

We ran into a few equipment problemsgetting the XP3 in the air and this isprobably the place to cover those.

The PS30 servos had some issues. Theyboth had a very bad buzz near center.The right wing servo would freeze inthe up aileron position (very bad!).Thermal drift was quite noticeable.Going from the basement to the fieldrequired about 50% change in subtrim. Both servos drifted the samerequiring and the exact sub trimcorrection is definitely the temperaturedependent. The HS55’s in the fuselagedid not exhibit any of these problems.

After shortening the servo arms, re-gluing the servos in the wells andchanging from metal to nylon clevises,the buzz got down to manageableproportions and the right servostopped jamming in the up position.However, the drift never went away.

First outing at the field showed thatthe CG setting was good (I use themost rearward setting I can handle)and the elevator throw could be cutdown by ~ 25%. Flaperon differentialwas good with no rudder coupling.I’ve since found that I like just a hair ofrudder coupling to keep the nosetracking a bit better in the turns. OtherXP3 flyers prefer no coupling. Flapthrow was a bit generous and neededto be cut back. That’s what ~ 1/3 chordflaps will do for you!

What turned out to be the last toss ofthis outing had a fortuitous glue jointfailure. The landing was in tall grassbut with a slight crabbing motion andthe vertical stab twisted completelyfree of the boom. If I had done the FullMonty on a discus launch it wouldhave been all over.

Close inspection of the failure indi-cated good wetting of the carbon boomand the vertical stab with the CA. Theglass was also well penetrated but theglue failed at the glass interface.Apparently the CA hadn’t polymer-ized properly in this area and was verybrittle. Foam-safe CA can be touchy on

shelf life and this one must’ve had it. Itwas fresh from the store but whoknows how long it had been on theirshelf?

Repair was my trusty Goop and balsafairing which has never failed me overmany crashes with my own designs.Please note that neither the PS30chatter/drift nor the stab joint failurewere XP3 problems. But they arethings to watch for because this ship isjust too nice to mess up with stuff likethat.

With various repairs complete, it wasoff to the field again. By now it’s 8:45PM and it’s almost dark but what theheck. A few hand tosses and every-thing looks fine. Re-center the PS30’sfor the 85F temperature and we’reready to go.

First shot is a gentle spin and releaseand ÖÖ WOW! The XP3 took off like ascalded cat and I wasn’t even trying.Gyro setting is perfect as the launch isstraight and true right from the release.Turns are great. A little down trim tohandle the rearward CG a bit betterand we’re all set.

The next few launches get a bit morevelocity into it. Absolutely everythingworks superbly on this airplane.Launches are incredible. At my age I’min that geezer category where I can’tget supersonic launch speed but thisship is sure making me look awfullygood!

Last flight is nearly full force. Well, asfull as a fat old guy with a bumshoulder can get. The plane just keepsgoing and going and Ö. ooops, it’s sodark now I can’t see it at the top anymore. A little strategic positioning andthe plane can be silhouetted between astreet lamp and the full moon for avery nice little flight. There are lots ofbumps and wiggles from the after darklow level turbulence.

After about a minute it’s full flaps anddown stick to bring it home. Belowabout 10 feet I can’t see it at all buthear the ssssshhhh into the grass a fewfeet away. Then just follow the buzz-ing servos until I’m close enough tofind it and we’re done for the night.

Since then we’ve had several veryenjoyable outings with the XP3.There’s a reason this is probably the

August 2003

premier DLG kit on the market rightnow. The construction is excellent. PhilBarnes wings are as close to perfectionas you can get. The Drela airfoils worksuperbly. The control set up is prettymuch right on the money. The launchheight is outrageous. What more can Isay?

As a post-script for this project, lastnight the flying was great and launchtechnique was being refined. After aparticularly towering zoom, it wastime to work on the flap and elevatortrim for rapid decent. After a couple ofturns for setup, the flaps were de-ployed and the left wing servo lockedin the down position! About all youcan do at this point is watch it spiraldown and play with rudder andelevator to try and keep the impactmoderate. When it hit on the nose andright wing tip it just bounced!

Inspection of the damage showed asmall tear near the hatch and a wrinklein the flaperons about 2/3 of the wayout on the wing. This is a certifiablytough airplane. My home built planeswould not have survived that dive andimpact!

Note that this servo was the OTHERone that had not been locking up. Atthis point the gears are stripped onboth flaperon servos, probably fromthe impact, so one unfortunate lessonfor me is don’t use PS30’s in this, orany other aileron DLG. They may befine for indoor electric but the center-ing, buzz and lock-up are not worthputting a plane like this at risk. We’llbe back in the air as soon as thoseDymond 60’s get here!

Be judicious in choosing the equip-ment to install in this ship. It deservesthe best and will give you all of thatback in performance when you get itright. I may never win a contest inDLG but I’m still having the time ofmy life with this airplane. It’s reallyput the fun back in flying for me.

Thanks Denny!

n

SCHEDULE OF SPECIALEVENTS

September 19-21, 2003Golden State X.C. Race California Valley, CAMike Gervais, (408) [email protected]

September 20-21, 2003Last Fling of Summer Broken Arrow, OKDave Register, (918) [email protected]

October 10-12, 2003Texas National Tournament (TNT) Dallas, TXwww.SLNT.org

October 17-19, 20032003 Electric Soaring Moriarty, NMWorld Challengewww.soarabq.org

November 29-30, 2003Tangerine Soaring Orlando, FL Championshipswww.orlandobuzzards.org

Please send in yourscheduled 2003 events

as they become available!

Golden State X.C. Race

September 19, 20, & 21, 2003California Valley,California

Special Announcement

With the cooperation of C.V. Lodge owner Ken Tabb, we have moved thestart finish line and launch area next to the C.V. Lodge. This will allowpilots to set up and launch within walking distance to the Lodge andrestaurant. In addition, the course has been expanded to a 50K or 31 milecourse; most of the course is on pavement, and still offers an unobstructedflight path as far as trees and other vehicle traffic. The new course has allthe features which can develop the world famous lift that C.V. is know for.

We are excited to announce that the South Bay Soaring Society is sponsor-ing the Golden State X.C. Race, September 19, 20 & 21, 2003. This Race isthe ultimate challenge in cross country soaring. It is 3 days of fun andcompetition for all levels of X.C. soaring. September 19th, Friday, will be acourse practice day. We will also offer LSF levels 3, 4, & 5 task goal andreturn markers set on course. Level 2 witnesses will be available to sign offyour completed tasks.

California Valley is located at the northern tip of the Carrizo Plain NaturalArea Preserve. the reserve is predominately shrub and grassland whichprovides an arid basin allowing wide open spaces for the best thermalactivity. It is bordered by the Tremblor Mountains to the east and theCaliente Mountains to the west. The central feature is Soda Lake, one of thelargest undisturbed alkali wetlands in the state. In May, the lake may haveevaporated leaving behind a glistening expanse of white salts whichilluminates your sailplane as it is crossing.

The South Bay Soaring Society would like to welcome any and all pilots toparticipate in this fun and challenging event. If you have any questions orwant additional information, please feel free to call me.

(408) 683-4140 or [email protected]

Thank you for your interest and hope to see you there.

C. D. Mike Gervais

R/C Soaring Digest

For our most recent project, the BlackbirdXC, we installed flaps in the wings andplaced an actuating servo, an Hitec HS605BB, right over each flap. We ended upusing a Y-harness to drive the two servos.Since the servos were mounted facingoutward, one turned in the correctdirection, the other in the opposite. Whatwould be the best way to reverse thedirection of rotation of one servo?

We did an internet search (“servoreversing”) and found a number

of available in-line servo reversers.These electronic devices are similar toextension cables and contain a smallcircuit board which changes the signalso the connected servo rotates oppositeto the factory-set direction. All of thereversers we found cost around $20.00,and the connectors fit most any servoor receiver. There are a couple of theseservo reversers which are designed toreplace the standard Y-harness. TheseY-harness cables send the normalsignal to one servo and the reversedsignal to the other, and at least one hasbuilt-in noise reduction circuitry so it’sbetter suited for use with longer leads.

But somewhere in the deep recesses ofour minds we seemed to rememberreading that a servo can be reversed byexchanging the motor leads andexchanging the two outer wires on thepotentiometer. We wouldn’t need topurchase servo reversing circuitry ifwe could confirm that procedure beingcorrect.

Another internet search (“reversingservos”) found <http://www.barnyard-buzzards.com/Builders_Corner/Electronics/index.htm>. This page is on the website of the Barnyard Buzzards, a powerclub in the Monroe Washington area.Photos and accompanying text depictthe elevator control system on an MATAirTrax, an IMAA legal airplane. Thislarge aircraft requires two servos todrive the elevator, a situation whichmandates one servo be reversed.Down near the bottom of the page is asimple method for reversing a servo.As a pleasant surprise, a photo of apartially disassembled HS 605BB servoleads off the instructions, showing

there is a lot of working roominside. The remainder of thephotos show how to modify thesmaller HS 85 for reversed rota-tion.

Simply stated, our foggy memorywas right on. You want to ex-change the two wires on the motorso it runs backwards from thenorm, and exchange the two outerwires on the potentiometer so thefeedback signal is reversed. Doingthis of course voids any warranty,so make sure you’re up to somefine soldering before pulling thecase apart.

Rather than unsolder and thenresolder directly to the small SMT(Surface Mount Technology)circuit board, as described on theBarnyard Buzzards page, wedecided to cut the four wires, barea small portion at each end, solderthe wires in the reconnectedpattern and slide some shrinktubing over each of the joints toreestablish the insulation.

The HS 605BB has a lot of roominside due to the large size of themotor, the small size of the circuitboard and potentiometer, and thelocation of the potentiometer at thevery top of the case. There wassufficient slack to pull the wires upand out of the case for easieraccess once the circuit board wasremoved from the case andpushed aside.

The orange and brown motorleads were cut at a point just pastthe edge of the motor. The red andgreen potentiometer wires werecut closer to the circuit board sothe soldering iron would not haveto be put inside the case.

To bare the end of any of thewires, the insulation must be heldfirmly in place with tweezerswhile a wire stripper is used. Ifyou don’t hold the insulation inplace, it pulls off the wire. We slidshort lengths of very small shrinktubing over the longer leads before

soldering the wires together in theirnew positions. Once the joints cooled,the shrink tubing was smoothed overthe soldered joint. Because the wiresbend once the case is put back to-gether, the tubing will not slip. Giventhe close surroundings, plastics andelectronics, there’s no room to manipu-late a heat gun anyway.

After carefully folding the potentiom-eter wires under the board and bend-ing the motor wires around the motorcasing, we seated the circuit board inposition and put the casing backtogether. Before screwing the caseshut, we hooked up the modified servoand its twin to the Y-harness. Bothworked flawlessly. Once the case wasback together, a permanent sticker wasplaced on the outside of the servo to

Modifying a Servo for Reversed Operation

by Bill & Bunny [email protected]

August 2003

note the reversed rotation modifica-tion.

The leads to the two flap servos arearound 20 inches in length, the leads tothe elevon servos are nearly four feet.All of the cabling in this airplane istherefore twisted to reduce the possi-bility of noise in the signal lines. This isaccomplished by taking the flat servocable and splitting it into three sepa-rate strands. The strands are then

twisted for the entire lengthand held in place while a heatgun is applied to set the twist.

While we had the HS 605BBservo apart, we took a goodlook at the mechanics. It’s apretty impressive piece ofmachinery for its $30 price tag.It has dual ball bearings andvery large plastic helical gears(a metal gear set is available,#6397), puts out 77 oz-in oftorque, and can rotate 60degrees in 0.16 secs on 4.8volts. Weight is 1.73 ounces. Afew minutes in time and aminuscule amount of solderproved to be an educationalexperience which saved $20.00and eliminated a possiblesource of in-flight electronicfailure.

n

R/C Soaring Digest556 Funston Drive

Santa Rosa, CA 95407

e-mail: [email protected]://www.b2streamlines.com/RCSD.html

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RCSD encourages new ideas, thereby creating a forum where modelers canexchange concepts and share findings, from theory to practical application.Article topics include design and construction of RC sailplanes, kit reviews,airfoil data, sources of hard to find items, and discussions of various flyingtechniques, to name just a few. Photos and illustrations are always inabundance.

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August 2003

T.W.I.T.T.(The Wing Is The Thing)

T.W.I.T.T. is a non-profit organization whosemembership seeks to promote the researchand development of flying wings and othertailless aircraft by providing a forum for theexchange of ideas and experiences on aninternational basis. T.W.I.T.T. is affiliatedwith The Hunsaker Foundation which isdedicated to furthering education andresearch in a variety of disciplines. Fullinformation package including one back issueof newsletter is $2.50 US ($3.00 foreign).Subscription rates are $20.00 (US) or $30.00(Foreign) per year for 12 issues.

T.W.I.T.T., P.O. Box 20430El Cajon, CA 92021

www.twitt.org

The Eastern Soaring League (ESL) is a confederation of Soaring Clubs, spread across the Mid-Atlantic and New England areas, committed to high-quality R/C Soaring competition.AMA Sanctioned soaring competitions provide the basis for ESL contests. Further guidelines arecontinuously developed and applied in a drive to achieve the highest quality competitionspossible.Typical ESL competition weekends feature 7, or more, rounds per day with separate contests onSaturday and Sunday. Year-end champions are crowned in a two-class pilot skill structureproviding competition opportunities for a large spectrum of pilots. Additionally, the ESL offers aRookie Of The Year program for introduction of new flyers to the joys of R/C Soaring competition.Continuing with the 20+ year tradition of extremely enjoyable flying, the 1999 season will include14 weekend competitions in HLG, 2-M, F3J, F3B, and Unlimited soaring events. Come on out andtry the ESL, make some new friends and enjoy camaraderie that can only be found amongst R/CSoaring enthusiasts!

ESL Web Site: http://www.e-s-l.org

The League of Silent Flight (LSF) is an internationalfraternity of RC Soaring pilots who have earned theright to become members by achieving specificgoals in soaring flight. There are no dues. Once youqualify for membership you are in for life.The LSF program consists of five “AchievementLevels”. These levels contain specific soaring tasksto be completed prior to advancement to the nextlevel.Send for your aspirant form, today:

League of Silent Flightc/o AMA

P.O. Box 3028Muncie, IN 47302-1028 U.S.A.

http://www.silentflight.org

SailplaneHomebuilders

Association (SHA)

A Division of the SoaringSociety of America

The purpose of theSailplane HomebuildersAssociation is to stimulate interest in full-sizesailplane design and construction byhomebuilders. To establish classes,standards, categories, where applicable. Todesiminate information relating to constructiontechniques, materials, theory and relatedtopics. To give recognition for noteworthydesigns and accomplishments.SHA publishes the bi-monthly SailplaneBuilder newsletter. Membership cost: $15U.S. Student (3rd Class Mail), $21 U.S. RegularMembership (3rd Class Mail), $30 U.S. RegularMembership (1st Class Mail), $29 for All OtherCountries (Surface Mail).Sailplane Homebuilders Association

Dan Armstrong, Sec./Treas.21100 Angel Street

Tehachapi, CA 93561 U.S.A.

Classified Advertising PolicyClassified ads are free of charge to subscribersprovided the ad is personal in nature and does notrefer to a business enterprise. Classified ads thatrefer to a business enterprise are charged $5.00/month and are limited to a maximum of 40 words.RCSD has neither the facilities or the staff to inves-tigate advertising claims. However, please notifyRCSD if any misrepresentation occurs. Personalads are run for one month and are then deletedautomatically. If you have items that might be hardto sell, you may run the ad for 2-3 months.

For Sale - Business

PARACHUTES: $12.50 (includes S&H U.S.A.)Send check or money order to Dale King, 1111Highridge Drive, Wylie, TX 75098; (972) 475-8093.

Summary of Low-Speed Airfoil Data - Volume 3 is reallytwo volumes in one book. Michael Selig and his studentscouldn’t complete the book on series 3 before series 4was well along, so decided to combine the two series ina single volume of 444 pages. This issue contains muchthat is new and interesting. The wind tunnel has beenimproved significantly and pitching moment measure-ment was added to its capability. 37 airfoils were tested.Many had multiple tests with flaps or turbulation ofvarious configurations. All now have the tested pitchingmoment data included. Vol 3 is available for $35. Ship-ping in the USA add $6 for the postage and packagingcosts. The international postal surcharge is $8 for surfacemail to anywhere, air mail to Europe $20, Asia/Africa$25, and the Pacific Rim $27. Volumes 1 (1995) and 2(1996) are also available, as are computer disks contain-ing the tabulated data from each test series. For moreinformation contact: SoarTech, Herk Stokely, 1504N. Horseshoe Circle, Virginia Beach, VA 23451 U.S.A.,phone (757) 428-8064, e-mail <[email protected]>.

Reference Material

BBS/Internet

Internet soaring mailing listserve linking hundreds ofsoaring pilots worldwide. Send msg. containing theword "subscribe" to [email protected]. The"digestified" version that combines all msgs. each dayinto one msg. is recommended for dial-up users on theInternet, AOL, CIS, etc. Subscribe using [email protected]. Post msgs. [email protected]. For more info., contact MichaelLachowski at [email protected].

Books by Martin Simons: "World's VintageSailplanes, 1908-45", "Slingsby Sailplanes","German Air Attaché", "Sailplanes bySchweizer". Send inquiries to: Raul Blacksten,P.O. Box 307, Maywood, CA 90270,<[email protected]>. To view summary ofbook info.: http://home.earthlink.net/~raulb

There is a growing interest in scale soaring inthe U.S. We are dedicated to all aspects ofscale soaring. Scale soaring festivals andcompetitions all year. Source for informationon plans, kits, accessories and other peopleinterested in scale. For more information:

web site: www.soaringissa.org

InternationalScale SoaringAssociation

R/C Soaring Digest

r/c soaring digest - aug 2003

Documents