Page 1June 2004

June, 2004Vol. 21, No. 6

R/C Soaring DigestPage 2

Copyright © 2004 R/C Soaring Digest.Published by b2streamlines.com

All rights reserved.

TABLE OF CONTENTS

3 "Soaring Site" ................................................................................ Judy SlatesEditorial ...............................................................................................................RCSD on the Web

4 "On The Wing..." ............................................................ Bill & Bunny KuhlmanFlying Wing Design & Analysis .................................................................................Diva, Part 3

8 "Have Sailplane, Will Travel!" ........................................................ Tom NagelExpo Coverage .............................. Trekking to Toledo, HSWT Visits the Weak Signals Expo

13 "Gordy's Travels".......................................................................... Gordy StahlFlying Techniques ................. All Mixed Up! V-Tails Aren't Always - Flaps Can be Ailerons

16 AMA Safety Committee Announcement............................................................................................................................... Emergency Safety Alert, Lithium Battery Hazard

17 "The Natural Side of Thermal Soaring" ..........................................Lee MurrayWeather's Impact on RC Soaring ............................................................................ "Big Air Day"

21 "The Winch Scene" ....................................................................... Jim Monaco....................................................................................................... New Winches - A Club Project

25 Technical Analysis & Design ......................................................... Mark Drela........................................................................................................ Airfoils, Planforms, and Twist

26 Event Announcement .................................................................Mike Gervais........................................................................................ Golden State X.C. Race Contest Results

RCSD Staff & Feature Columnists

Judy Slates: Managing Editor, Article Submissions“The Soaring Site”

B2 Kuhlman: Publisher, Internet Support, Columnist“On the ‘Wing...”

Dave Register: Video Coordination, Technical Editor, Columnist“Tech Topics”

Lee Murray: Historian - Keeper of the Index, Columnist“The Natural Side of Thermal Soaring”

Jerry Slates: Technical Editor, Columnist“Jer’s Workbench”

Gordy Stahl: Advertising Coordinator, Roving Correspondent“Gordy’s Travels”

Tom Nagel: Travel Saga Correspondent“Have Sailplane Will Travel!”

Mark Nankivil: Columnist“Electric Connection”

Greg Smith: Columnist“The Sloper’s Resource”

Dave Garwood: Photographer, Writer

About RCSD

R/C Soaring Digest (RCSD) isa reader-written monthly

publication for the R/Csailplane enthusiast and hasbeen published since January,1984. It is dedicated to sharingtechnical and educationalinformation. All materialcontributed must be exclusiveand 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 themeaning of a story. Becausewe encourage new ideas, thecontent of all articles are theopinion of the author and maynot necessarily reflect those ofRCSD. We encourage anyonewho wishes to obtain addi-tional information to contactthe author.

Page 3June 2004

TheSoaring

Site

Judy SlatesRCSDigest@aol.com

http://www.b2streamlines.com/RCSD.html

SAGE COMPULSION

Dynamic soaring inFrankfort, Kentucky,

Gordy Stahl flies a SageCompulsion. Speed wasapproximately 100 mph.

Photography by BruceDavidson (past DHLG NatsChampion) from Louisville,Kentucky.

RCSD on the Web

This month, for their contributions to the electronic version ofRCSD, special thanks go to:

Jimmy Andrews, TX via SingaporePaul Debry, FLMike Glass, TXKeith Love, CA

Richard Weil, Australia

It’s also thanks to Richard Weil, an original subscriber to RCSD, fortaking the time, not only to express his appreciation for all the yearsof RCSD, but to request e-mail notification as issues become availablefor downloading. B2 researched the possibility of e-mail notificationand the end result is a Yahoo! Group called RCSoaringDigest:

http://groups.yahoo.com/group/RCSoaringDigest

There is also a link off the RCSD home web page that takes youdirectly to the Yahoo! Group. (This is not a discussion group, ratherit’s designed for notification purposes only.)

Thanks go to B2 for establishing the Group!

Another person deserves the limelight this month. Craig Burtonasked a simple question regarding a series of old articles and, in thecourse of our e-mail correspondence, Craig asked if he could helpcreate PDF documents of old issues. We discussed the process, ransome tests and, as of this writing, Craig has completed his first twoPDFs, January and October 1988. (Thanks for volunteering Craig!PDF conversion is extremely time consuming; if you get bored, pleaselet us know!)

B2 are also working on PDF documents having completed the firsttwelve issues of RCSD: January - December 1984. And, our own DaveRegister has also volunteered to help! (Thanks, Dave!) And me? I’vecompleted 2001 and now working on year 2000.

While we plan on making those issues available soon, we’re alsolooking out into the future, attempting to analyze the magnitude ofour undertaking. How much server space will ultimately be requiredis a number one priority. For those of you downloading RCSD PDFfiles, you’ve likely noted that most of the past issue PDFs are actuallybeing downloaded from <http://soaring.ryanflowers.com/rcsd-pdf/>. Ryan Flowers, Reno Nevada, has devoted substantial space on hisserver to the RCSD endeavor. We really appreciate Ryan’s help in thisarea. Thank you, Ryan!

Having only one site in the future would be great but, at this stage ofthe conversion process, it is certainly not necessary. If any of youhave spare server space you can share, we’d like to hear from you!

R/C Soaring DigestPage 4

bsquared@appleisp.nethttp://www.b2streamlines.com

Photo 1: Aileron bellcrank mount.

Photo 2: Aileron pushrod.

This has been an exciting series ofweeks for us because Diva construc-tion has progressed rapidly. As thiscolumn is being written, the entireframework is complete and all radiogear has been temporarily installed.The airframe, minus covering andpainting, weighs 1300g, a bit under46 ounces, which is right on target.

Finishing the wing

The most critical part of wingconstruction is the D-tube

formation. Once the upper andlower sheeting is bonded to thespars, ribs, and leading edge, it’snearly impossible to take out orput in any wing twist. Becausethe Diva wing uses a triplereverse taper, we set up threeseparate sets of jigging fixtures.As we had made templates for allof the wing ribs, getting heightsand angles for the various fixturepieces was a simple, but timeconsuming, matter.

After getting all of the ribs gluedinto place on the spar and addingall of the trailing edge pieces, thewing was jigged into positionright side up and the uppersurface leading edge sheetingwas glued onto the structure,along with all of the uppersurface rib cap strips. Thisprocedure was performed onboth wings.

The wings were then invertedand aligned again. Using the ribtemplates, we made sure therewas no twist built in. Because therear upper surface of the wing isvery slightly concave, it’s pos-

Diva, Part 3

Page 5June 2004

Photo 3: Aileron bellcrank mount.

Photo 4: Aileron pushrod.

sible to set up the wing so that itis self aligning. Once assuredeverything lined up properly, thelower surface leading edgesheeting was attached to the sparand ribs. The leading edge stockwas then glued on with the wingstill in place in the jig, followedby the lower surface rib capstrips.

The aileron bellcrank is mountedon a piece of 1/16th plywoodwhich is attached to two adjacentribs. See Photo 1. The pushrodfrom the bellcrank to the aileroncomes out of the bottom of thewing. Since this is in an open bay,the covering must have some sortof attached substrate. We used alarge piece of specially cut 1/64thplywood for this purpose. Thepushrods come straight out of thecutout from the bellcrank, andthen bend back to the controlsurface through a 90 degreeangle. Photo 2, taken beforecovering was applied, shows theaileron linkage and wing cutoutto good effect.

Vertical fin and rudder

Choice of an airfoil for thevertical fin and rudder wasdependent upon the aft fuselagetaper and the need for an airfoilwhich could also be used for thesub-fin. To make the transitionfrom the fin and rudder to theventral fin easier to configure, welooked for an airfoil with flatsides for most of the aft portion.We selected the BTP8 sectionfrom our archives. This sectionwas originally designed for use inmodel rockets, but in the past hasalso been used with success fortail surfaces on conventionaltailed RC models. We’ve in-cluded a coordinate table for thissection along with a low res plot. The maximum thickness point of the BTP8 is just ahead of 20% chordand the surfaces are straight lines from about 30% chord to the trailing edge. The trailing edge lends itselfwell to sheet balsa construction, as it is very thin and blunt.

Some mathematical skills were required to get the templates for the diagonal ribs printed out, as thepercent thickness of these ribs changes slightly along the rib length. We started cutting balsa once wewere sure each of the ribs matched the width of the fin trailing edge. Fin construction consisted of block-ing the leading and trailing edge off the table and adding ribs at 90 degrees to the spruce fin trailing edge.The base rib was then oriented to match the top of the fuselage and glued into place, as was the end rib.The rough cut tip block was then glued in place.

Rudder construction was fairly straightforward as the entire structure has a triangular cross-section. Theforward edge is a square C-shape structure, the trailing edge is simply two sheets of 1/16th balsa lami-

R/C Soaring DigestPage 6

Photo 6: Elevator control system.

Photo 5: Completed fin and sub fin.

nated to a central core of 1/64thplywood. The triangular rudderribs were easy to make as all thatwas needed was the leading edgewidth and total length.

The tip block was shaped inoutline and cross-section, and allexterior surfaces were sanded toaccept plastic shrink coveringmaterial. You can see the com-pleted fin and rudder, along withthe ventral fin discussed next, inPhoto 3.

Ventral fin

Because the vertical tail tends toget blanketed when the wing is athigher angles of attack, we’vealways made sure there issubstantial ventral fin area. Theventral fin was designed to drivethe wing to below its zero liftangle upon touchdown, prevent-ing ballooning following abounce. This surface, while ofextremely low aspect ratio, mustalso be able to absorb potentiallylarge side loads which may beimposed during touchdown.

The ventral fin core consists of a1/8th plywood rim mounted on abalsa base rib which maintainsthe vertical tail airfoil. 1/16thhard balsa sheeting is then edgedto match both the base rib andfuselage surface on one edge andcreate a large gluing surfaceagainst the plywood rim. Theinitial pieces of sheeting must becarefully positioned in order tokeep this fin precisely alignedwith the fuselage. We used the method shown in Photo 4.

The completed ventral fin, as shown in Photo 5, will eventually receive a layer of one and a half ouncefiberglass along the edge which comes in contact with the ground. Additional ’glass cloth will then beapplied to tie the lower portion of the fuselage into the structure and strengthen the balsa sides againstthose side loads.

Elevator control system

The elevator control system described in Part 2 was installed in the fuselage before the top sheeting wasglued on. Photo 6 shows the installed internal system and pushrod. This is a no slop system which is bothrigid and free moving.

The elevator halves were cut free of the main wing panels and set aside until the control mechanism wasinstalled in the fuselage. Once we knew where the control arms exited the fuselage, placement of thebrass tubes in the elevator was undertaken. This involved taping the elevators to the wing in the neutralposition and sliding the wing into position. We marked the elevators using a 48 inch straightedge, thendrilled out the ribs by hand to accept the brass tubing receptacles. Some plywood pieces were glued tothe balsa ribs and within the trailing edge to spread stresses across larger surfaces.

Page 7June 2004

At the field, the wingslides along the mainwing rod a short distanceand the elevator driverods are then inserted intothe brass tubing recep-tacles in the elevators. Theservo wiring is plugged inwhile the gap is relativelylarge. As the wing is setagainst the wing-fuselagefillet, the incidence pinplugs into a brass tube inthe wing near the elevatorhinge line.

The future

Next month’s column willfocus on the fuselage andthe wing-fuselage fillet-ing. A consistent line ofquestioning at the flyingfield starts with some-thing like, “How do youshape such a sleekrounded fuselage from abunch of balsa andplywood?” For thisreason, particular atten-tion will be paid totransforming the fuselagefrom its original primitivesquare cross-section into amuch more aerodynamicshape. Additionally, we’llshare some photos of thecompleted airframe.

Since we’re so close tofinishing Diva, we’realready trying to chooseour next constructionproject. Potential buildsinclude an R-2 enlarged toXC size, a Raven S ofeither 100 inch span orenlarged to XC, and aRaven FF adapted to RC,but we’re open to othersuggestions. Go to theRCSoaringDigest Yahoo!group page <http://groups.yahoo.com/group/RCSoaringDigest/> and click on “Polls.” Letus know what you thinkwe should tackle next!

Don’t forget, we’realways available at P.O.Box 975, Olalla WA 98359-0975 or through<bsquared@appleisp.net>.

R/C Soaring DigestPage 8

Troy Lawicki’s first place RES Duck.

The Southern Kite

By Tom H. NagelColumbus, Ohio

tomnagel@iwaynet.net

HAVE SAILPLANE, WILL TRAVEL!

Trekking to ToledoHSWT Visits the Weak

Signals Expo

On March 15th the buzzardsreturn to Hinkley, Ohio. A

month later, tax returns are due.In between those dates each yearRC fans from all over feel theurge to migrate to the SeagateConvention Centre in Toledo,Ohio for the massive WEAKSignals RC Expo.

Page 9June 2004

The Avenger

Northrop N9M

This year was the Expo’s 50th Anniversary. For RCSailplaners, the show can be summed up as follows:

50 years270 commercial vendors

5000 plus attendeesand about 6 sailplanes.

I have been going to Toledo for about ten years. Thisyear I drove up with Don Harris who has been attend-ing since the early 70’s. It seemed to both of us thatthere were fewer sailplanes to be seen than in prioryears. On the other hand, The Expo is a gigantic event,and half a Toledo is better than none.

We were both psyched. To me it felt like a combinationof Christmas morning and the first day of deer season.Don told me he’d been awake since 3 a.m. “Boy, arewe a couple of terminal sailplane geeks or what?” Ithought as we headed north from Columbus at 6:30a.m.

The show opens a 9 a.m.; I have the drive timed soclosely that we pulled into the parking garage at 8:58a.m. We entered through the maze-like swap shop areaon the second floor mezzanine. I cruised fairly quicklythough the swap shop, but it was still 10:30 a.m. beforeI even made it to the box office to buy my ticket. (Yesindeed, the swap shop is a free event. You could spenda whole day, even a whole weekend, or a whole IRSrefund check in the swap shop and never buy a ticketto the show.

In past years I have ogled many a used sailplane in theswap shop. My acquisitions there have included an

R/C Soaring DigestPage 10

John Ferguson holding the Picalario module.

DJ Aerotech “Roadkill” scale N9M

LSF Officers

original Ken Bates flying wingand a beautifully built 2MChrysalis by Dave Leach. Thisyear I didn’t see a single sailplanein the swap shop.

The guys who make an insanelylarge line of coroplast andCanadian downspout-pipepower planes did have a shortvideo of a coroplast pterodactylsloper. (Say that three times realfast!) Check out<www.plasticconceptplanes.com>.They might just have a SPADsloper. But not at the show.

I spent a few minutes at thecrowded Sky and Technologybooth talking to owner TerryRollins about the new universalsynthesized receiver he is mar-keting. The $75 eight channel unitis claimed to mate with a trans-mitter of any make and anyfrequency, and will reject signalsfrom any other transmitter, evenon the same frequency. The Skyand Technology receiver hasbeen the subject of a lot ofdiscussion on RCSE recently. By10 a.m. on Saturday, Terry hadalready run out of all of hisliterature and even his businesscards. He was limiting receiverbuyers to “forty per person.”

Also worth a look is Rollins’smaller (8 grams) 7 channelreceiver that he sells for $40. Itwill accept any single conversioncrystal and like its big brotherlock onto your transmitter to theexclusion of all others until deathdo it part. This unit is model No.CRX-M7. Check out Sky and

Page 11June 2004

John Gill’s 1916 Burgess-Dunne flying wing seaplane

Tom Skully’s K-8 (Mark Gellartand Seve Sibenaler inspecting it).

Technology’s website at<www.4mht.com>.

When I finally worked my waydown to the jam packed mainfloor, my first destination was theLeague of Silent Flight booth. Thenew LSF officers were there togreet folks and pass out vouchersand distribute RCSD’s “GettingStarted in RC Soaring” pamphlet.Pictured are Tom Kallevang,President; Larry Storie, VP; JimDeck, Secretary; and SteveSiebenaler, Treasurer. OutgoingPres. Jack Strother and PrincessMonokote were also at the showSaturday, but had the freedom toroam the convention center for achange.

In the booth next door JohnFerguson was demonstrating thePicolario vario. For those of youwho have not seen a picture ofthat tiny device, here it is.Ferguson and Picolario areworking on upgrade modules,which will eventually enable thePicolario to read out speed,current draw, voltage, tempera-ture and other variables.

The Evolution on display at thePicolario booth and the plane inthe LSF booth were two of thevery few sailplanes on display.Tower Hobbies had a Bird ofTime ARF in their area but nokits to sell. Northeast Sailplanehad a 12-servo scale monster on arotating display, and it looked to

be a DLG with a built-up wing. I think Sal should have gotten aspecial award for either “sailplane requiring the most servos” or“commercial booth with Sailplane in its name but almost no sail-planes.”

Mr. Sobox was there with a beautiful electric sailplane on display, butapparently no kits to sell. Other than a few Zagis at Jerry Tiesan’sbooth, that was it for sailplanes in the commercial area.

Missing this year were Skybench Aero, Gordy and Volz, DennyMaize and Polecat Aero, M & M Modeltech, Dymond and manyothers. I have a theory:

The Weak Signals Expo features a large static display contest. Thecontest categories are sort of arcane:

military scale boat

R/C Soaring DigestPage 12

designer scale planeworking vessel unarmednon-military sport scalebest unarmed forkliftbest small sport steam powered

ornithopterand so forth.

For all the categories you can check theExpo’s website <www.toledoshow.com>.Sailplanes are waaaaaaay at the bottom. Ithink one of the problems is that the WEAKSignals folks lump all the sailplanes togetherin one category. We need to lobby for morecategories, like the power folks have done:

Best Thermal DurationBest Thermal Scale Sailplane

Best Power Scale SloperBest Woodcrafter Sailplane

Prettiest FoamyPrettiest Mantis

Tom Skully Model of the Year

NSP’s 12 servo monster.

Let’s get to work on the Weak Signals folks and see if we can’t get them to give us more niches to fill!

The sailplane entries this year were:

Troy Lawicki’s 118” RES Duck, which won the sailplane category. The Duck was beautifully finishedwith molded in spoiler hinges and a nice orange sauce.

Tom Skully’s 148” Scale K-8 from a Flair kit. Tom won second place. He has carried away first placeat Toledo for several years with a series of beautiful models. The K-8 had pull-pull controls on bothrudder and elevator. Late in the day I saw an elderly gentleman with a big grin on his face and a FlairK-8 kit on his shoulder, heading for the parking garage. I wonder where he got the idea.

Ed Wilson entered the Southern Kite, which is both NOS and RES legal. This was another unusualentry, which got a lot of attention from glider pilots. It won third in the sailplane category.

John Wolf entered a nubblie nosed Avenger.

John Diniz entered a Tragi Limited.

And Dale Corven showed a Sharon RES.

Due to the dearth of sailplanes at Toledo, I decided to send along some flying wing photos for Bill andBunny Kuhlman. The giant semi-scale Northrop N9M spans twelve feet and nine inches and is poweredby two OS .46 engines with 17” propeller shafts. One of the engines is custom made to counter rotate. Theplane weighs 16 pounds. The airfoil is an Eppler 334. Aircraft design was done using Compufoil andDesigner CAP. Leading edge sweep is 22 degrees and twist is 4 degrees. Two little electric GWS ductedfan units are tucked into the air intakes to keep the gas engines cooled while the plane is ground maneu-vered.

DJ Aerotech, formerly sailplane manufacturers and currently providers of fine Roadkill electric models,were showing their own profile scale N9M. Don Stackhouse showed me how the prototype N9M featuresnose wheel steering and flies on rudder and elevator controls, with no mixing required. The productionversion will likely sport split wingtip drag rudders just like the full sized Northrop wing.

A beautiful scale model of an early biplane flying wing was also entered in the competition. My photosdo not do justice to the beautifully detailed woodworking and engine detailing.

Don and I headed home late in the afternoon, foot weary, lugging bags of batteries, magazines andassorted goodies. We’d seen lots of friends and met lots of new folks and we’d gotten our RC fix for theweek. And there is hope for sailplanes at the Weak Signals Expo. This week gas prices hit a record level of$1.80 per gallon. Who knows? By next year, we may be the only ones who can afford to fly!

• • •

Page 13June 2004

GORDY’S TRAVELS

Gordy StahlLouisville, KentuckyGordySoar@aol.com

All Mixed up!V tails Aren’t Always

- Flaps can be Ailerons

V-tail, Flaperon, Spoileron,Rudder/Aileron Mix,

Elevator to Flap, Flap to Elevator,Elevator Compensation, Multi-Point Elevator CompensationMix, and Differential are termswe see in the menus of ourtransmitter and hear about all thetime, but may seldom under-stand.

In this article I intend to debunkthe mystique behind these terms!It’s important for ThermalDuration competition pilots tohave a clear understanding ofevery single component of theirsailplanes. Currently it’s notunusual for the average thermalcompetition RC sailplane pilot tohave closer to $2,000 in his modelrather than $1,000. It just doesn’tmake sense to possess thatamazing capability withoutoptimizing its set ups.

So begins this trip!

While on a recent trip to Hous-ton, Texas, I was presented withthe challenge of using a Stylus TXfor a V-tail RES KummerowSearcher.

The owner couldn’t understandwhy he was having troublegetting the TX to work his plane.He had engaged the ‘V-tail’ mix,and got elevator working prop-erly on both halves of the V tail,but couldn’t get his right stick

(aileron) to work the rudderfunction.

It was interesting that he knewthe names of the functions butcouldn’t seem to separate them inhis mind from which transmitterstick should be operating them.

If you have a sailplane with a Vshaped tail group and no aile-rons, V tail function is NOT thefunction you want to engage. Yousay, “Come on Gordy, you’reway off on this one!” But in fact Iam not.

The rear of the plane has twocomponents: V shaped or crosstailed. Those functions areRudder and Elevator. Seemspretty simple right? So then whythe confusion?

Let me state their names again:Rudder and Elevator. Thecombined name for this set up isRudder-vator, a combination ofRudder and Elevator, and it’sthat function (Rudder-vator) thatis engaged when using the “V-Tail” mix on all transmitters,since the beginning of time.

The confusion comes into playwhen we forget that a V Tail isRudder and Elevator, which iscontrolled by ALL transmitters,using the Left stick (side to side)to operate Rudder and the Rightstick to operate Elevator. No oneI’ve met uses two sticks tooperate sailplanes with onlythose functions.

They use the Right stick (up anddown) to operate elevator, andalso use the Right stick to operatethe ‘rudder’.

However, the right stick is theAileron Function. So a twochannel sailplane outfitted with aV-shaped tail group is actually acombination of Aileron andElevator functions. This iscommonly referred to as Aile-vators, and they provide theexact same functions as Elevons,Elevator and Ailerons, mixed for

use on tail-less sailplanes such asthe Zagi type wings.

Right stick & Right TRIMS.

I was telling this story to a localclub mate who has been at thishobby a lot longer than I havebeen and, not so surprisingly, hetold me that one of our memberswas using the V-tail Mix functionon his Stylus and it was workingfine! I tried to clarify that, whilehe had the V-tail Mix turned on,he was actually only ‘sort of’making it work.

By using the Rudder to AileronMix function in combination withthe V-tail Mix, he was allowed touse the Right stick to operate hisRudder-vators as if they wereAile-vators. However, while hecould certainly ‘fly’ his V-tailedRES ship that way, using only theRight stick, in fact his RudderTrim was the only way to trimhis V-tail.

That was because he was actuallyusing the Rudder channel, notthe Aileron channel.

So here are the V-taildefinitions again:

V-tail – A V-shaped tail group.

Rudder –Vator – a mix combi-nation of Rudder function andElevator function which, on theTransmitter, means the left stickand right stick are mixed, thefunctions mixed when engagingthe “V-Tail” mix in your trans-mitter.

Aile-Vator – a mix combinationof Aileron and Elevator, bothfunctions located on the Rightstick.

So if you have a RES sailplanewith a V-tail, you will want tohave both functions on the Rightstick. To do this, you need toengage the Elevon Mix function,sometimes called Delta WingMix, so that your Aile-vatorswork properly and your trims are

R/C Soaring DigestPage 14

both on their correct locations.

But, IF you have a full house shipwith a V shaped tail group, thatis ailerons, elevator, rudder andflaps, then “V-tail’ Mix Function(Rudder-Vators) is the correctfunction, putting the V-tail’soperation on the Rudder stickand on the elevator stick, withailerons working on the Rightstick.

Ailerons used to act as Flaps, orto act as Spoilers is anothercommonly mis-represented ormis-understood function.

Spoilers work differently thanFlaps. Flaps provide lift throughcambering the wing; Spoilersreduce lift by flattening the airfoilon top. When ailerons are used toassist the lift capability of thewing, this function is called“Flaperons.” That’s when bothailerons are used (full span, noseparate flaps) to create lift ordrag by setting them down toadd undercamber to the wing.

Flaperons deployed characteristi-cally cause the model to balloonits nose upwards because of theadded lift they create.

Spoilerons on the other hand, un-camber the wing, reducing liftand characteristically whendeployed usually cause themodel’s nose to drop as the winghas less ability to ‘lift’ its ownweight much less the entireairframe.

So Flaperons (mixing flaps foradded wing camber with theaileron function) cause the modelto balloon upwards andSpoilerons cause the model todrop. The idea of mixing aileronswith flap or spoiler is to avoidusing two more servos, andhaving two separate flaps orspoilers.

Full house ships DO use amodified version of Spoileronsand Flaperons when flaps andailerons are mixed to movetogether. In that case the aileronsare put to work helping create lift(Flaperons) and the flaps are putto work as added aileron length.When the ailerons are used as

‘Spoilerons’ along with the flaps,the function is mostly consideredReflex, the idea not so much usedfor landing assist, but rather toclean up the drag of the airfoil forimproved penetration whenreturning from downwind.

Our sailplane functions aresimple and sometimes that makesthem confusing. But just remem-ber that Rudder is on the left stickand aileron is on the right stick.V-tail function is a mixing ofRudder Stick and Elevator stick,not a mixing of the aileron stickand the elevator stick.

So while your sailplane’s tail maybe V-shaped, it is likely not beingused as a conventional “V-tail,”Rudder/elevator, but rather itmay be set up as an Aile-vator.

IF you don’t take time to clearlyunderstand your sailplane’sactual functions and how theyare controlled from the TX, you’llnever be good at hitting a spotlanding or likely not making yourtask time.

SO if your TX doesn’t haveElevon, Delta, or Aile-Vatorfunction, what to do? Well, youcan use the V-tail function andthen use the Rudder to AileronMix function. Or you can get anelectronic two channel mixerwhich would allow you plug inand have the mixing doneelectronically.

Rudder Aileron Mix - why?

First, use it because you paid forit when you bought your trans-mitter! Next, because when youwant to ‘turn’ your sailplaneusing only aileron, various thingscause your sailplane to roll, butnot axially. Instead it’s likely thatthe fuselage will angle upwards,so that the nose is diagonal to theground - nose attempting to goupwards.

That means that the energy yoursailplane has will be dissipated inits attempt to drive upwards onthat diagonal, when in fact youwant all the energy going aroundthru the turn. (Hope that makessome sense.)

You always hear about making‘coordinated turns’ which, ifperfect, would be like a trainriding on rails thru a turn, versusyou hopping on one leg througha turn. One is very efficient andone isn’t.

By initiating some rudder com-mand it gets the nose of the planemoving ‘around’ instead ofaround and up. So, how muchmix should you use? Most say setthe mix at about 50%, but with alittle in flight experimenting youcan actually dial in the ‘right’amount. Remember if, withoutrudder used in the turn (non-coordinated), your model anglesup and around, and a perfectturn (coordinated) would be onethat has the fuse coming aroundparallel to the ground, too muchRudder Mix would make the turn‘un-coordinated’ or the fuse nosewould angle down and around.Again your goal is to roll thesailplane into a bank without achange in pitch (nose up ordown).

Elevator to Flap

First read that phrase out loud toyourself and identify which ofthe two is the ‘boss’. In this caseElevator is being tied to theOPERATION of the Flap. So Flapis the boss. When the flap ismoved down, the Elevator can bemixed in to keep the model fromeither ballooning or diving. Sincethe first phases of down flapcause increased wing camber (liftstrength), that causes the front ofthe plane to pitch upwards. Butmostly it causes the wing to havemore DRAG. Think in terms of apassenger jet landing; the flapsgo way down, drag is dramati-cally increased so the pilot pourson the throttle to keep the planemoving ahead versus stalling. Healso puts in some down elevator.This keeps the plane in the flightattitude he wants and movingforward.

Since our sailplanes don’t havethrottles to add more thrust wehave to rely on gravity to increaseor maintain our ‘power’ - that’sdown elevator. So it makes senseto use in flight camber to make

Page 15June 2004

the sailplane a little floatier inlight lift. Or, for strong lift, dial ina little down elevator.

So how much is enough? Againthis is a pretty simple commonsense evaluation. While flying,our goal should be to maintain auniform airspeed while flyingthermals. No diving and climbingthrough the circle, which createsairspeed increases and masks theability to read air conditions.

Fly the sailplane level with justenough up trim to maintain a flat(flat does not mean a diagonalglide to the ground!) hands offglide. Move the flap to camber tothe desired amount and see whateffect it has on the model’sattitude and speed. If you noticethe model pitches up, or slowsnoticeably, dial in some downElevator to Flap mixing.

Flap to Elevator

Who’s the boss here? Same asbefore, one being tied to theother. In this case it’s the Flapthat is being slaved to the Eleva-tor. Why? This function allowsthe pilot to ‘help’ the sailplanemake its movements (turns) in amore efficient format and allowsthe pilot to ‘cheat’ some bycambering the wing slightly toassist the nose and model ingeneral in its climb during athermal turn without babysittingthe elevator during the turn. Thisfunction became popular duringslope racing, as it shortens theradius of the turn withoutburning off as much airspeed ashorsing the elevator did. Oftenreferred to as ‘pump’ or ‘snapflap.’ Flap to Elevator combineslift with pitch.

How much is enough? This one isa lot trickier, but keep this singlethought in mind. The more youcamber the wing, the more dragyou create; the more drag youcreate the slower your modelflies; the slower your model flies,the more it sinks. So 1/8” to 3/16” full deflection is about thelimit. This is one worth ‘playing’with.

Elevator Compensation Mix

This function is usually used as adevice during landing. It givesthe pilot the ability to hold themodel on a level plain with eitherthe deployment of lift killingdevices such as Spoilers/Spoilerons or reflex, which causethe sailplane to drop its nose byautomatically feeding in upelevator in degrees as thosedevices are deployed. Or to keepthe sailplane from pitching up byfeeding in down elevator indegrees with the deployment ofFlaps, Flaperons or camber. Thisone is a big deal and is importantto get right. Again, the goal is tohave the sailplane maintain itsglide path angle without pitchingup or down as either is deployed,regardless of airspeed changes.So if you have too much or toolittle elevator compensationdialed in, as your Spoilers orflaps are deployed, simplyremove or add some elevatorcompensation in until the modelstays on path regardless of howmuch of either you have in at anypoint in deployment.

Multi-Point ElevatorCompensation Mix

Think about it. For this explana-tion I will talk about Flaps, butthe same logic applies to the useof Spoilers.

In the initial stages of deployinglanding Flap to slow thesailplane’s decent down, thewing’s ability to create lift isgreatly increased; since thishappens usually with fairly highairspeed, it’s likely that thesailplane’s nose will want topitch up. But as the Flap contin-ues downward, changing fromcamber to just drag, and sinceadded lift dissipates (bothbecause of less camber andbecause declining airspeed), lessdown elevator is needed at fulllanding flap deployment.

So with most sailplanes, if youhave enough down elevator tocounteract the pitching caused bythe camber, then you’ll likelyhave too much for when thesailplane slows with full flap,

causing the sailplane to be divingwith full landing flap deploy-ment. Multi-Point ElevatorCompensation Mix allows thepilot to have an automaticadjustment or relationship to theflap stick position, providing lotsof down elevator on the first partof the stick and less at the end, alltoward the goal of keeping thesailplane on a consistent glidepath.

Differential

I hope you’ve been following myarticles in recent past editionsbecause I have gone into theimportance of understanding theuse of aileron Differential. This isanother one of those settingsoften dismissed with, “Set it atabout 50% less down than upaileron.” When in fact it really isa very important contributor tothe efficiency and value of thewhole sailplane’s performancethat you paid all that money for!When one aileron is deflecteddown, it creates both lift anddrag; the lift part is good, but thedrag part is bad. It causes the oh-so-dreaded ‘adverse yaw.’Simply put, if you wanted to‘turn’ right, that adverse yawwould drag the sailplane’s leftwing back, causing it to yaw(turn) left when you were hopingto yaw (turn) right. It’s an energykiller for sure.

How much is enough? Whileflying the sailplane in calmconditions, trimmed for easyhands off flat and level flight(rudder/aileron mix OFF!),simply rock the aileron stickextremely quick back and forth;take care not to mix elevator stickmovements into this experiment.IF you have too much or too littledifferential, the model willWIGGLE its tail while you movethe stick, versus staying straighton path. Then if you have theAileron Differential set just right,the sailplane’s roll should beaxial, not barrel looking.

We pay big bucks for a Transmit-ter that gives us capabilities; it’sup to us to get our money’sworth from them. Sailplanes areall about energy, making the best

R/C Soaring DigestPage 16

possible use of the energy outside our models (versus from a motor).

Take some time to travel the Mixing ‘road’, one leg at a time. Think about each item and then go out andexperiment in the sky with the TX settings. However, if you have that little bit of extra nose weight (forextra stability), don’t expect any of the above to be easy. Figuring mixing, starting with a crooked sail-plane, is a challenge.

So go back to my article on balance “Gordy’s Balancing System.” Get the sailplane balanced, and not bymeasuring some spot as the sailplane teeters on some pegs on the bench! Balancing a sailplane can onlybe done where it ‘works’ - in the air! Then have fun with Mixing!

Hope you enjoyed this trip!

AMA Safety Committee AnnouncementApril 23rd, 2004

EMERGENCY SAFETY ALERTLithium Battery Hazard

From AMA Safety Committee

Lithium Battery Fires

Lithium batteries are becoming very popular for powering the control and power systems in our models.This is true because of their very high energy density (amp-hrs/wt. ratio) compared to NiCads or otherbatteries. With high energy comes increased risk in their use. The, principal, risk is FIRE which can resultfrom improper charging, crash damage, or shorting the batteries. All vendors of these batteries warn theircustomers of this danger and recommend extreme caution in their use. In spite of this many fires haveoccurred as a result of the use of Lithium Polymer batteries, resulting in loss of models, automobiles, andother property. Homes and garages and workshops have also burned. A lithium battery fire is very hot(several thousand degrees) and is an excellent initiator for ancillary (resulting) fires. Fire occurs due tocontact between Lithium and oxygen in the air. It does not need any other source of ignition, or fuel tostart, and burns almost explosively.

These batteries must be used in a manner that precludes ancillary fire. The following is recommended:

1. Store, and charge, in a fireproof container; never in your model.

2. Charge in a protected area devoid of combustibles. Always stand watch over the charging process.Never leave the charging process unattended.

3. In the event of damage from crashes, etc., carefully remove to a safe place for at least a half hour toobserve. Physically damaged cells could erupt into flame, and, after sufficient time to ensure safety,should be discarded in accordance with the instructions which came with the batteries. Never attemptto charge a cell with physical damage, regardless of how slight.

4. Always use chargers designed for the specific purpose, preferably having a fixed setting for yourparticular pack. Many fires occur in using selectable/adjustable chargers improperly set. Neverattempt to charge Lithium cells with a charger which is not, specifically, designed for chargingLithium cells. Never use chargers designed for Nickel Cadmium batteries.

5. Use charging systems that monitor and control the charge state of each cell in the pack. Unbalancedcells can lead to disaster if it permits overcharge of a single cell in the pack. If the batteries show anysign of swelling, discontinue charging, and remove them to a safe place outside as they could eruptinto flames.

6. Most important: NEVER PLUG IN A BATTERY AND LEAVE IT TO CHARGE UNATTENDEDOVERNIGHT. Serious fires have resulted from this practice.

7. Do not attempt to make your own battery packs from individual cells.

These batteries CANNOT be handled and charged casually such as has been the practice for years withother types of batteries. The consequence of this practice can be very serious resulting in major propertydamage and/or personal harm.

Page 17June 2004

http://raob.fsl.noaa.gov.

R/C Soaring DigestPage 18

Note: We now offer a new FSL output format, and a skewt display format.

Page 19June 2004

Text File [x .txt]

R/C Soaring DigestPage 20

Page 21June 2004

THE WINCH SCENE

Photo 1. Old Winches Before Disassembly

Photo 2. Handle Attachment Cut-out (The hole on top isthe stake-down hole, and the ring on the side is to attachthe handle pin when not in use.)

Photo 3. Bare Frame After Powder Coating

The Rocky Mountain SoaringAssociation has been a

chartered AMA club since 1976.Though it seemed like thewinches were that old as well, thereality is that the club built thecurrent 5 winches that we usestarting back in the late 80s. Youcan see some of the variousversions in Photo 1. Last year along-time club member, MarkHoward, donated a trailer he hadto the club for the transport of thewinches to and from our contests.In the past the club winches wereallocated to willing (or unwilling)volunteers who took then homeand were responsible for gettingthem to the contests. This wasalways a headache for the CDwho had to call all the winchmasters and ensure that theywere going to attend the contestor arrange for the transport to thecontest if they were not. Thetrailer simplified this process, onemember stores the trailer andeither brings it to the contest orarranges some other member tobring it. All of the stuff necessaryfor running our contests is in thetrailer – frequency pins, landingtapes, scoring equipment, tables,chairs, etc. The only thing miss-ing is the computer.

We have a process where, oncethe winch master brings thetrailer, we randomly select 6pilots at the contest to be “WinchMaster for a Day.” These pilotsare responsible for setting up andtearing down the winches, andreloading them into the trailer.This was always painful, sincethe existing winches weredifficult to set up, the wheelsneeded to be removed before use,each winch was different andsubsequently we often hadequipment problems because thewinch masters were unfamiliar

New Winches– A Club Project

Jim MonacoRocky Mountain Soaring Association

Denver, Coloradowww.rmsadenver.com

JimMonaco@Earthlink.net

R/C Soaring DigestPage 22

Photo 4. Completed Winch – Note the handleslides into the receiver for compact storage.

Photo 5. Front View – You can see the rubber bandused for belt tension to the bolt on the brake arm.

with each winch setup. Werecord who did the duties, and atthe next contest we select onlyfrom those pilots that have notyet been a winch master. Wheneveryone has had the “opportu-nity” – we start the list over.

Based on the need to reduceweight and the desire to havesmaller, easier, and consistent toset up winches, we decided tobuild all new winches over thewinter. I took the lead in prepar-ing the design for the winchesand researched a number ofexisting designs. None of thecommercial designs really fit ourneed to have a wheeled frame todrag into the sod farm thatprohibits motorized vehicles, so Idecided to create a new design.The new design goals were:

1. Be light and compact.2. Easy to set up – just stake it

in.3. Integrated storage for the

handle so we don’t havethem bouncing aroundseparately.

4. Wheels big enough to pulleasily thru the sod.

5. Robust brake arms. (Webreak a lot of these on thecurrent winches.)

6. Enough extra parts andtools to field repair anymechanical failures.

Making measurements, I de-signed the smallest frame thatwould hold all the components,then went to Home Depot andbought enough steel to fabricateone prototype frame. Most of theprototype components were easyto get with a few exceptions. The.25” thick steel vertical motormount needed to be cut a specificsize with a 2.125 round cutout forthe motor, so I went to a weldingshop with a plasma cutter andgave them the dimensions and 3days later had a nice mountingplate. The other pieces that weredifficult were the brake armcomponents. For this I contactedthe local aluminum supplier andhad him cut some rectangularaluminum stock 1.5” x .5” x 7” forthe basic arm, and some 1”diameter aluminum cylinder forthe belt hold down. With some

help from the neighbor and his MIG welder we welded all the piecestogether and had a basic frame complete. It’s a good thing it was aprototype! Assembling the components showed that I was tooaggressive on cutting the size down. It was a real challenge to geteverything mounted. I got some wheels from the farm store, and wewere ready to rock.

After about 1 month of near daily use, I looked for what changeswould be necessary for the production winches. First the shape of thevertical motor mounting plate was changed to allow more space forthe components. The handle attachment point was also redone. Theprototype showed some side to side bending from the way thehandle attached. This was cured by making the cutout smaller, thusstronger, and by using a fitted hitch pin to transfer the side loads

Page 23June 2004

Photo 6. Winch with Handle Extended

better. See the handle cutoutpicture in Photo 2. The frameitself was also widened about 1inch to allow more room for thetools box to be attached. Withthese changed the design met ourrequirements. I built one moreprototype and documented thebuild and assembly process, thenit was time for the productionbuild.

We decided to do the build intwo stages. Day 1 we would cutand weld all the parts together,clean up the frames and thensend them out to be powdercoated. We decided that wewould build 8 complete frameswith 2 being kept for expansionand the 6 completely built out forour contests. After the framesreturned from powder coatingwe would disassemble the oldwinches and assemble the newones.

I made a parts list and ordered allthe steel to be cut. Instead ofHome Depot, I found the parts tobe much cheaper at the localindustrial steel shop. They alsocut the 8.25” steel mountingplates. Member Charlie Millerdonated the use of his auto repairshop one day while it was closedto do the work. This was great,since we had plenty of room,workbenches, vices and any toolsthat we forgot to bring. We goteveryone that showed up work-ing, cutting metal, sanding, polishing, drilling, etc. Dr. Dan Williams, and Mark Howard volunteered todo the welding and they did a great job. Their first job was to weld up a jig that we used to hold thecomponents together while they welded the corners. This worked great and all the frames came out leveland true. As they finished welding, the cutters gave them new components while other folks took theframes and cleaned up the welds. After about 6 hours we had 8 new frames and handles ready to go topowder coating. It was amazing how well everyone worked together to get them to this point. I took all 8frames to the powder coater the next day and in one week they were done and BEAUTIFUL. The finishedunassembled frames are shown in Photo 3.

Now it was time to schedule final assembly, again at Charlie’s Garage. A mostly new crew showed up forthis operation. One incentive was that we would give the old frames to any member that came to help,first come, first serve. So we began by disassembling the old winches; we basically salvaged the motors,drums, power switches, and everything else was new. I brought all the nuts, bolts, solenoids, switchwiring and a written set of assembly instructions to get things going. Charlie had pre-assembled all thewiring using #2 welding wire, and soldering on nice connectors on the ends. Don Ingram predrilled all ofthe brake components, so they were also ready to assemble.

I took everyone that came, divided them up into teams of 2, each assigned the task of disassembling –then assembling one winch. Although the instructions were pretty good, there were definitely somethings I overlooked and some components were assembled a couple of times. The good thing is that theprototype was there as a model for everyone to look at. There were really only two significant issuesencountered during the assembly. First, although I used on of the switches as a model for the prototype,it was discovered that the mounting plates were slightly different on each of the other winches which

R/C Soaring DigestPage 24

made for some fiddly work getting the switches mounted. Second,the drum brakes seemed to have some loose screws holding themon, but when we tightened the screws we could not get the drumson the motor shaft. After much consternation we finally used anair grinder to ream out the inside of the brake shaft to get theclearance we needed with the bolts tight. After about 6 hours wehad a great looking set of club winches. Winch details are shownin Photos 4-6. We lost a total of 150 pounds of weight that greatlyhelped the trailer. The 6 winches loaded in the trailer are shown inPhoto 7.

This was a great club effort, where the rewards were first reapedin March at our first contest. The new winches set up and teardown quickly, and operated near flawlessly. The ‘near flawlessly’is tempered by a couple of backlashes due to the new brake beltswhich, until they get broken in, tend not to be as effective asnormal. To solve this problem we simply put a rubber band on thebrake arm to give it more tension. By the end of the contest thebands were not needed any more.

The total cost for building 6 complete winches and 2 backupframes was about $1200 (including 5 new Linemaster pedals).Note that this did not include motor, drum, or power switcheswhich were reused, but did include the costs for the prototypes.The club is very happy with this investment of approximately $200per winch and 2 spare frames for expansion.

Thanks go out to all the club members that supported this effort;they are too numerous to mention, but all the club membersappreciate their involvement.

• • •

Photo 7. The LoadedWinch Trailer

Last year, we received asimple e-mail request:

“I’m trying to find a placeto buy a sailplane winchwithout much luck, couldyou please help?”

That request which wasanswered behind the scenesand Mike Garton’s recentcolumn in the May 2004issue of Model Aviation,triggered a series of e-mailmessages among theauthors and columnists ofRCSD.

The outcome was thecreation of a new columncalled “The Winch Scene.”It will pick up whereMike’s column left off,providing more detailwhere it’s available.

We encourage anyone whohas a hint, tip, photo orsuggestion on the subject ofwinches to send it to<RCSDigest@aol.com>.

Judy SlatesRCSDigest@aol.com

Page 25June 2004

R/C Soaring DigestPage 26

Atomic FireballRich Spicer & Fred Olsen

EliasJohn & Marketa Elias

TunaMike Gervais, Scott Meader,

Dean Gradwell

G-forcePaul Gradwell, Bob Claar, Ron

Mc Cellion

Broken-ArrowJim Rolle & Bruce Moore

NecronGreg Norsworthy & Noel Siegel

GOLDEN STATE X.C. RACECalifornia Valley, California

Contest Results

by Mike Gervais

We had six teams from as far north as Oregon and as far south as L.A., CA. The first day’s task was adistance task running the course in the direction you entered it, i.e. clockwise or counter clockwise,

and using the turnpoints on the outside of the course, 50k circuit. The only way you could reversedirection was to come back to the launch site and relaunch. The second day’s task was the speed taskwhich is to fly as far as you can as fast as you can. This task allows you to use the various turnpoints oncourse. There was a minimum flight time of 2 hours and max of 3 hours. The first day’s distance task totalfor six teams was 195 miles for an avg. of 33 miles per team. The longest flight of the day was 63.2 milesor 101.1 K for pilot Rich Spicer for # 5 100k pin. The second day’s speed task avg. speed was @ 12 mphwith the fastest being 23.95 mph for pilot John Elias.

Saturday Distance

Team Miles Points PlaceAtomic Fireball 63.2 1000 1stTuna 57.7 913 2ndNecron 32.7 518 3rdElias 22.5 356G-force 11.2 177Broken-Arrow 10.4 165

Sunday Speed

Team MPH Points Place OverallElias 23.9 1000 1st 2ndAtomic Fireball 20.0 836 2nd 1stNecron 18.4 768 3rd 3rdG-force 14.4 597Tuna 8.6 361Broken-Arrow 6.3 263