Vol. 21, No. 5

May 2004

May, 2004Vol. 21, No. 5

R/C Soaring Digest

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...................................................................................................... "Getting Started in RC Soaring"

4 "Electric Connection" ...............................................................Mark NankivilEvent Coverage .................................................................................................... JR Aerotow 2003

9 "Jer's Workbench" ......................................................................... Jerry SlatesTraining .......................................................................................................... Training Techniques

10 "On The Wing..." ............................................................ Bill & Bunny KuhlmanFlying Wing Design & Analysis ......................................................................................................................................................................... Inside the Richter R/C Skunkworks: Project Alula.............................................................................................................. Guest Author, Steve Lange

14 "Tech Topics"............................................................................. Dave RegisterTechnical Analysis & Design .................................................................... Gorilla Glue Anyone?

16 "Gordy's Travels".......................................................................... Gordy StahlFlying Techniques ............................................. Going Up? Understanding Sailplane Surfaces

17 FAI News

18 Battery Maintenance ......................................................................Rick Eckel.... The Voodoo Theory of Battery Maintenance (The Basics of Rechargeable Battery Care.)

19 "The Winch Scene" .......... Dave Register, B2, Dave Garwood, Jerry Slates, Gordy Stahl...................................................................................... Safety Tips, Observations, Winch Photos

23 Technical Analysis & Design ......................................................... Mark Drela.............................................................................. Sizing of Wing Joiners for Required Strength

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.

NEW!

May 2004

TheSoaring

Site

JR Aerotow 2003

Dan Troxell’sscratchbuilt 40% scale

model, Grunau Baby IIb,attended the JR Aerotow2003 event held inMonticello, Illinois. MarkNankivil covers the eventthis month in his column“Electric Connection.”

Photography byMark Nankivil.

RCSD on the Web

Sometimes, things seem toogood to be true. And, because

of the many questions we havereceived since March 11th, I wantto assure you that RCSD is,indeed, now free.

By way of explanation, I’d like toshare an e-mail message from AlGroke, Kansas.

“I look forward to readingSoaring Digest on-line. I likearticles on airfoils with coordi-nate lists. I make and fly onlyfoam core wings and fuselageplanes, so articles on that subjectare appreciated. I’m thinking ofbuilding a lost foam hollow corewing on one of my next planes sohints on that would be nice.”

I’ll pass your request along to theother team members. We’ll see whatwe can do.

“I would pay a subscription tothe on-line version if past issuesare available and searchable.”

We appreciate the offer, but havedecided to provide RCSD free ofcharge to any that can download it.As of this writing 25 issues areavailable for download: April 2002-April 2004. As time permits we planto pdf prior issues. Lee Murray hasbeen preparing an index of articlessince the beginning. It’s alsoavailable for downloading off themain page of our web site.

Last month, we promised tothank those of you that havecontributed to the electronicconversion since the April issuewas made available. Specialthanks go to:

Brian Allen, VABarney Bauer, MI

Charles Botzko, OHJ.D. Bourne, EnglandJonathan Bryan, WA

Joe Chovan, NY

Judy [email protected]

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

Tim Christison, CAJohn Cyr, AZ

D.O. Darnell, OKAl DeRenzis, MD

Bud Elder, FLPaul, Emerson, AZ

Jim Gell, MIDoug Gordon, FL

Al Groke, KSBert Hollifield, NCRay Holzheuer, INBrian Johnson, TX

Bruce Johnson, CanadaBrian Molloy, MO

Al Nephew, MN via IrelandBruce Rose, OR

Roger Segers, BelgiumHendrik Tillema, OK

Bill Warrick, INBrenton Watkins, AK

Max Whitson, CARichard Williamson, MARyan Woebkenberg, IN

“Getting Started inRC Soaring”

“Getting Started in RC Soaring,”as some of you already know, is ahandout available for download-ing from the web site. Whatmany of you might not be awareof is that it’s undergone a com-plete revision this past month.

When we realized that there wasa deadline to complete therevision, the RCSD Team jumpedin to discuss potential planes andradio configuration for a begin-

ner based on what’s availabletoday, cost being an importantfactor.

The latest revision may bedownloaded and freely repro-duced, as was recently done byTom Kallevang, President of theLSF. The handout was madeavailable at the LSF booth duringthe Toledo Show. Our thanks toTom for the heads up!

R/C Soaring Digest

Asher Carmichael brought this 6.5 meterspan CNC Modellbautechnik Ka-6CR.

Dan Troxell came from California and brought anumber of models including this DG500M Elan.

This model was one of the casualties of Friday the13th with a spectacular disintegration at altitude.

The mixture of full size and scale sailplanes atthe hangar was eye catching.

With the continued popularity of aerotow events, it

was great to hear that JR Radiosand Horizon Hobbies would besponsoring just such an eventhere in the Midwest, and not farfrom where I live in St. Louis. Sowith my calendar marked forJune 13th thru 15th, I was happy tosee the day arrive as I packed upthe van and headed down theroad into Illinois.

JR Radios and Horizon Hobbiesare both based in Champaign,Illinois and with JR’s own PeterGoldsmith spearheading theevent, it was a natural for Peter toset the event up in nearbyMonticello, Illinois where helives. Peter is a very accom-plished flier in a number ofaspects of our hobby from TOCsize pattern ships to large scalesailplanes. Peter arranged for theevent to be held on the home turf

ELECTRIC CONNECTIONby Mark Nankivil

[email protected]

JR Aerotow 2003

May 2004

Rick Richardson flew thisscratchbuilt 1/4 scale EONOlympia 2B built from theCliff Charlesworth plans.

Peter Goldsmith’s Towmauleheading back to the field.

Howard Thomas flew thisnicely built 1/4 scale Ka-8B

built from the Flair kit.

Mibo USA brought along a numberof their models and flew them

throughout the weekend. Check outtheir website at

<www.mibousa.com>.

Peter Goldsmith also flew this 6meter span ASH- 25 from a

Rosenthal kit.

Tony Fiorentino’s 40% scale Ventus C on tow.

R/C Soaring Digest

Tony Elliot brought two 10.3 meter span models, one being an ETA, a scratchbuiltmodel that uses a much modified Rosenthal ASH-25 fuselage. AUW of 45 lb. and

aspect ratio of 53:1, each wing panel is made up of 3 sections.

Big models need wide runways to land -Tony Elliot’s SB-10 about to touch down.

Peter flew this 33% Piper Cub whicheasily towed the largest and heaviest

sailplanes. Engine is a DA100.

Here’s the way to travel! TonyFiorentino’s models along with a

Nissan S2000 arrived at the field instyle in this trailer.

John Derstine of Endless MountainModels <www.scalesoaring.net>brought along and flew one of his

products, a fully molded 1/3.75 scaleDG1000 (not shown) from LET

Models. John Derstine’s two sons,David & Michael, took turns flying

their 1/3rd scale Ka-6E. A real beautyin the air and a very nice flier.

Rusty Rood’s ASW-15, a verynice 1/4 scale from Mibo USA.

May 2004

A truly beautiful model, Dan Troxellbrought this scratchbuilt 40% scale

model of the Grunau Baby IIb.

of the Illinois Glider Club (fullscale) which is based at PiattCounty airport, convenientlylocated on the south side ofMonticello. The club was verykind to allow the attendees accessto their hangar for storing themodels and shipping containers.It was pretty neat to see full sizeand not quite full size sailplanestogether in the hangar.

The weather in the Midwestthroughout May and June wasvery wet and the days leading upto the event saw a substantialamount of rain throughout mid-Illinois with Monticello receivingmore than its fair share. Therewere large ponds of wateradjacent to the runways and

parking area on the airportgrounds but the City’s publicworks employees did a great jobon Friday of eliminating the pondin between the parking area andthe runway being used for flying.Thankfully the weather turnedfor the better and conditionsthroughout the weekend wereexcellent with plenty of sun, goodlift and warm breezes. Add tothat the readily accessible food onsite which was handled by theMonticello Model Makers, thisturned out to be a great inauguralevent! CD Peter Bergstrom keptthings relaxed but well run andthe guys from JR were kept busyhandling the tow duties with anumber of different tow planesassisted by Johnny Berlin with his

Pegasus and Peter George withhis Townado. There was noshortage of towing capacity allweekend long! JR Radios andHorizon Hobbies also kept araffle going all weekend longwith plenty of great prizes beinghanded out. Anyone at the fieldcould also buy a raffle ticket for achance to fly in one of the twoseat gliders flown by the IllinoisGlider Club. All money raised inthis raffle went to the club andNelson Itterly was the lucky manwho took the ride on Saturdayevening in a KR-3 Kronos sail-plane.

It was great to see a number offliers and their models from thewest coast. JR was kind enough

R/C Soaring Digest

Rick Briggs rolling in on finalapproach with ASH-26.

Tony Fiorentino flew this huge 1/2 scale ASW-27 on Sunday.

2ND Annual International JR Aero Tow 2004

June 10-13, 2004Monticello/Piatt County Airport

Monticello, Illinois

http://horizon.hobbyshopnow.com/articles/1302.asp

This event is expected to draw more than 85 pilots for three days of scale soaring andaero-towing fun. Additional information, registration, and directions are available on theweb page shown above.

to handle the shipping of their models from JR’s west coast facilities and this enticed anumber of modelers to make the trek to the Midwest. Tony Fiorentino also flew upfrom Florida in his Mooney and others brought his large motorcoach/trailer loadedwith some truly large sailplanes.

There were a couple of crashes on Friday (Friday the 13th syndrome?!) but the week-end was pretty much accident free with only a few minor mishaps. The surroundingcorn fields and the lack of any nearby background made for a surprising number of offfield landings as it was hard to get good depth perception for the approach. No brokenmodels though and a quick clean up of the mud and the models were ready to flyagain.

There were plenty of fine eateries for the evening get togethers and the local commu-nity is filled with plenty of other interests too such as a very nice railroad museum onthe north side of town. Monticello has a very nice atmosphere which added to thefamily feel of the event.

There’s no doubt that this event was a tremendous success and I would highly recom-mend you come and make a weekend of it and enjoy next year’s event.

• • •

May 2004

Jerry Slates556 Funston Drive

Santa Rosa, CA [email protected]

Jer'sWorkbench

Stev Feuerbacher, doing the firstlaunch for Dave McGhee.

Stev Feuerbacher (L) - StudentDoug Skjerseth (R) - Instructor

Dave McGhee (R) - StudentDoug Skjerseth (L) - Instructor

Dave McGhee is workingon body language.

Training Techniques

Here at Clearlake in NorthernCalifornia, the Clearlake

Modelers R/C Club sets aside thefirst Sunday of each month andcall it Sailplane Sunday.

Sailplane Sunday in April turnedout to be an absolutely beautifulday for flying. The winds were 0-5 mph out of the east, shiftingaround to the north. The sun wason our backs and the temperaturewas in the low 80’s at ten o’clockin the morning. Not bad for themonth of April!

Doug Skjerseth, President of theclub, spent most of this beautifulday instructing two new clubmembers, Dave McGhee and StevFeuerbacher, about sailplanesoaring. Doug explained howand why a sailplane flies, thecontrols, radio, and buddy cordset-up.

Having explained the basics, thefirst thing that needed to be donewas to set up the high start. Dougsaid, “If you want to learn to fly,you also need to learn how to setup the high start.” And, so theydid.

Once the high start was set up, itwas onto the flying. First up wasStev. Another club member, GinoFerrario, helped by launching.Using the buddy cord system,Doug flew the plane off thelaunch and then turned thecontrols over to Stev. While Stevwas flying, Dave retrieved theline (retrieve one, fly one). As themodel neared the ground, Dougtook over the controls, landingthe model nearby. Dave flewnext, with Gino launching andStev retrieving. After round one,Doug, Dave, and Stev discussedtheir flights.

They repeated these steps for two

more rounds. For round 4,however, Dave launched for Stevand Stev launched for Dave.

They went on to fly 9 rounds andI believe that they had a really

good time! One of the reasonswas because Doug spent a greatdeal of time with them, carefullyexplaining all the basics neededin order to learn how to fly.

Doug’s parting words? “Nextweek, the winch!”

Thanks, Doug, a day well done!• • •

R/C Soaring Digest

May 2004

Alula Prototype #2 Specifications:

Wingspan: 32in. (813mm)Wing Area: 217in.2 (14dm)All Up Weight: 3.5oz. (100g)Wingloading: 2.3 oz./ft.2 (7g/dm)

Links:

Richter R/C, Michael Richter1250 Northridge Rd.

Santa Barbara, CA 93105http://www.dream-flight.com/

flyWeasel Yahoo! Group:http://groups.yahoo.com/group/flyWeasel/

Short Alula flight movie (2.5MB, Quicktime .MOV format):http://sbslopers.org/movies/alula/project_alula.mov

The organic Alula silhouette contrasts beautifullywith the overhead cloud base.

[email protected]://www.b2streamlines.com

(L) Michael Richter shows off hisbrand new Alula (prototype #1) onthe hillside behind his home. Themaneuverability of the relatively

small Alula makes it possible to flyaround trees, shrubs and otherobstacles in search of light lift.

As regular readers of RCSDknow, we wrote a kit review

of Michael Richter’s Weasel andminiWeasel just over a year ago.We were impressed with thequality and completeness of thekit contents, the ease of construc-tion, and the ruggedness andperformance of the completedaircraft.

While writing the review, wewere of course in contact withMichael Richter. In one piece ofcorrespondence he included aphoto of a test vehicle he haddesigned which sported forwardswept wings and a fixed fin at theend of a long slender boom. Itsrather unique planform intriguedus, and we encouraged Michaelto put out a kit. (The photoappeared in the article.)

We’re eagerly awaiting theappearance of that design, but inthe meantime Michael hasdeveloped another sloper withforward swept wings namedAlula. Steve Lange, Richter R/Centhusiast, placed some photosand a brief description of Alulaon the <flyWeasel> Yahoo group,

and we immediately contactedSteve in an effort to obtain moreinformation.

Alula is a compact lightweightEPP foam machine with forwardswept wings which excels at“slermal” (slope thermal) flying.The very light wing loading,maneuverability, and small size

make it ideal for taking advan-tage of light lift conditions andtight spaces.

With that as background, we turnover this month’s edition of “Onthe ’Wing...” to guest authorSteve Lange.

R/C Soaring Digest

One of the great things aboutliving in the same town as

Michael Richter is that you get togo over to his shop and take apeek at what he’s working on.Usually he’s busy filling Weasel-pro and miniWeasel orders (seeRCSD 2/03 for details), but fromtime to time he gets a break in theaction and a chance to do someR&D. That’s when the REAL funbegins!

The latest creation to come out ofthe Richter R/C “skunkworks” isan ultralight tailless forwardswept EPP glider named theAlula, scheduled for release inthe early summer. If you consultyour dictionary, you’ll see thatthe word “alula” refers to thethumb feathers on the leadingedge of a bird’s wing. Thesefeathers serve a similar functionto the leading edge slats used onfull size aircraft, helping to delaythe onset of a stall and keep theairflow attached to the wingsurface. Given the impressive lowspeed performance of the RichterR/C Alula, this name suitsMichael’s newest glider perfectly.

The Alula is a classic example ofa designer “scratching an itch.”Michael enjoys flying small tip-launched gliders around hishome in the foothills of SantaBarbara, where his backyardfrequently enjoys a soft up-canyon breeze and small

Steve Lange’s plane,prototype #2, with some

super-extra-custom Sharpiepenwork providing the

Alula “logo.”

On final approach, the Alulalooks very bird-like. Slow speed

behavior is exceptional.

INSIDE THE RICHTER R/C SKUNKWORKS: PROJECT ALULA

by Steve Lange

May 2004

This photo demonstrates some of thedifficulties inherent to flying around

Michael’s house, especially if youhave reflexes which are a bit slow.This Alula, one of Michael’s proto-types, is still flying, and very well!

thermals. On the downside, there are tall trees and scrub brusheverywhere, making retrieval of downed planes a non-trivial affair.Having a durable and highly maneuverable glider is of key impor-tance when your landing pattern frequently involves a downwindapproach beneath a tree branch, over a creosote bush and touchdownin an outstretched palm!

Happily, the same features that make the Alula an outstandingperformer in Michael’s backyard also make it great for ultralightslope lift and slermal (slope thermal) conditions at “normal” flyingsites. The forward swept planform is incredibly agile, allowing thepilot to slow forward flight to nearly a walking pace without any fearof stalling. Steeply banked 180° turns can literally be done around awingtip. It also makes for some of the prettiest thermal turns you’reever likely to see from an R/C glider; high in a thermal, the Alulalooks much more like a small soaring bird than an airplane.

Like the rest of Richter R/C’s offerings, the Alula is made from EPP,with one major difference: except for the competition grade balsaelevons, it is not taped or covered in any way. Leaving the airframeuncovered results in two immediate benefits: the plane’s all upweight is significantly reduced, and building time is cut by half ormore. At the low Reynolds Numbers at which the 32" wingspanAlula operates, it is questionable whether or not the rough surface ofthe raw EPP actually inhibits performance; it may actually improve it.Since the plane is so light (3.5oz./100g AUW) durability remainsgood. My prototype has been flying regularly since the end of 2003and it is still going strong.

The Alula uses similar construction techniques to the Weasel-pro andminiWeasel. The wing halves are joined using Weldwood contactcement or 3M77, the carbon spars are installed using thin CA, and theservos are held in place with a dab of hot glue. The fin, a uniquesymmetrical design that extends both above and below the wing likethe NCFM Bluto, is made from Depron and features its own carbonspar. As mentioned above, the elevons on my prototype are competi-tion grade balsa and covered in packing tape (the production versionmay feature Depron elevons; the design is still being finalized).

Michael and I have been flying our prototypes using the same sub-micro gear that the miniWeasel employs. My prototype uses twoCirrus CS-5.4 servos, a Cirrus MRX-4 Mk.1 single conversion receiver,and one of Michael’s 150mAh NiMH battery packs. With that setupthe Alula can be flown continuously for a little over an hour. Asmentioned, the AUW with this gear comes out to about 100g, whichresults in a wingloading of approximately 2.3oz./ft.2 (7g/dm).

As most of our flying sites here in Santa Barbara feature hills of onesort or another, I have yet to test the Alula in truly flat field condi-tions. Tip launches are not exceptionally high, probably averagingabout 40 feet. Obviously the Alula is not meant to compete with 1.5mhandlaunch gliders; its forte lies in the ability to be flown in crampedlocations where maneuverability and durability are key, as well asslermal and ultralight slope conditions. Low cost will be anotherattractive feature; Michael has indicated the kit will most likely retailfor less than US$50.00. That will make it less expensive than anyother EPP SAL glider on the market with the exception of theminiWeasel.

Overall, I’ve been very impressed by the Alula’s performance, andespecially its durability. I expected the uncovered plane to be muchmore fragile, but so far it has held up to my abuse extremely well.The forward swept planform looks cool, and more importantly it

works. I have yet to see anythingthat is as maneuverable andcontrollable at low speeds and intight spaces as the Alula. Itoutclasses both the Weasel-proand miniWeasel in this regard,and has definitely become one ofmy favorite airplanes. Hopefully,the Alula will meet the desires ofthe many Weasel-pro andminiWeasel owners who havebeen clamoring for a morethermal-oriented airplane. I knowI’m satisfied!

• • •

R/C Soaring Digest

TECH TOPICSGorilla Glue Anyone?

Just when you think you’ve seen all the adhesivesyou can handle, something new comes along. First it

was acetate, then Elmers, carpenters, epoxy, cy-anoacrylate (CA), various types of contact cement andhot melt. Now we’re into Gorilla Glue.

You may have seen this stuff on the shelf at your localhardware store - a dark brown plastic bottle with apicture of a hairy ape on the label. What in the worlddo we do with it?

Turns out, there may be quite a few uses for thisadhesive. As more modelers become aware of thisproduct, we’ll probably learn more. For now, let’s do abrief run through of what we’ve learned so far.

Gorilla Glue is a type of polyurethane (PolymericMDI). You can learn all the technical details and manyapplication hints from their website:

http://www.gorillaglue.com

You can also download an MSDS sheet (MaterialSafety Data Sheet), which is a good idea for under-standing any potential hazards. After looking over thissheet, the precautions are similar to many of theadhesives we commonly use – avoid skin and eyecontact, good ventilation, etc. Unless you have aspecific allergic reaction to this material, it appears tobe appropriate for general modeling use.

What’s so special about it? Well, it claims it grabseverything. It won’t dissolve in water once it’s cured. Itseems to be resistant to alcohol and mineral spirits,also post-cure. It foams to fill gaps if there’s a bit ofhumidity or moisture while the polymerizationprocess cures.

Bob Peck, our TulSoar president, first started using thisadhesive for EPP slope ships. If you’ve worked withEPP, the adhesive choices are limited. Epoxy works(sort of) but can be brittle. Silicone won’t grab EPPvery well at all. Contact cement (3M77 in particular) isgood but the carrier can eat the foam. Goop is prob-ably best since it grabs the foam pretty well and is notbrittle when it cures. Goop will mildly attack EPP ifyou put it on too thick.

Gorilla Glue seems to address all of those problems.It’s got a very tenacious grab when first applied.Unless it foams too much, it retains some ductilitywhen it cures. When it foams into a gap, it fills the areavery nicely. The excess foam can be trimmed and/orsanded easily.

Dave Register and Bob PeckTulsa, Oklahoma

Bob’s suggested experiment is shown in the firstset of pictures. We took three pudding cups(great for mixing resin for wing bagging, by theway) and added the same amount of gorillaglue in each. The first cup just had the glue, thesecond was lightly wiped with a wet brush andthe third had liquid water mixed with the glueand then the excess left in the cup.

The humidity in the air will cause some foam-ing (cup #1), but a slight amount of moisturewill help ‘kick’ the foaming reaction (#2). A lotof water results more foam and a somewhatbrittle material (#3).

May 2004

I’ve tried three applications so farthat work nicely – wood spars inan EPP Gentle Foamy, gap fillingin the wing saddle of an EPPFoam One-2 and Nyrod installa-tion, also in EPP. Although theapplications are quite differentthey all seem to be suitable.

For the spars, a moist acid brushwas used to leave a bit of a watercoating in the EPP spar groove. Gorilla Glue was applied to the spar and then pressed into the slot. Theexcess material that splooged out was mopped up with rubbing alcohol. The spar was covered withSaran, a metal straight edge was placed over the saran and then a few bricks on the straight edge. Threehours later I had a very well glued and gap filled spar installation.

For the Foam-One, I wet down the pine mounting board in the fuse, squirted on an excess amount ofglue, and screwed the wing in place. The bolts had been waxed. Saran was taped to the bottom of thewing. The next morning I had a pretty nice wing saddle!

For the Nyrod application, two rods were glued into a scrap of EPP. Both channels were routed with a0.125” Dremel router bit, wet down with the acid brush and Gorilla Glue squeezed into the slot. TheNyrods were pressed into the slots and rotated a bit to spread the glue.

In this experiment, one rod was wiped with alcohol while one was sanded to roughen the surface. Afterachieving a full cure, both rods were ripped out of the foam. The smooth rod had reasonably goodadhesion but the roughened rod was REALLY stuck in the channel and pulled out quite a bit of foam.

A few things to note:

This glue seems to grab best when it is first applied. After it begins to foam it doesn’t seem to stickvery well.

The foam that squeezes out and freely expands is easy to carve and doesn’t stick to monokote, saranor just about any smooth, low porosity surface.

It takes 30 minutes or so for the foam reaction to really ‘kick’ so you have a decent working time withthis adhesive.

If you maintain tight gaps, the foam will only expand into the little nooks and crannies. This stuffisn’t like household foam that will lift the Queen Mary. It just seems to fluff into the extra spaces andthen pretty much stop.

I’m sure there are some great applications for this material in other types of construction. For now it lookspretty good on EPP. If it can grab EPP it can grab just about anything.

Gorilla Glue is available in Lowe’s, Home Depot, etc. It looks like it’s a nice complement to the otheradhesives we use. Bob and I like what it does with EPP. And it cleans up reasonably well with isopropylalcohol.

And just imagine – you could be the first at your hill or field to be flying an 800 gram Gorilla!

• • •

R/C Soaring Digest

GORDY’S TRAVELS

Gordy StahlLouisville, [email protected]

Going Up?Understanding

Sailplane Surfaces

Itravel a lot and I get to talk to alot of sailplane pilots. The one

thing I have noticed is that whilethere are some great thumbs outthere, not many guys reallyunderstand what does what ontheir sailplanes.

If you have been following mytravels this season, you’veprobably noticed that I have beenwriting about what does whatwell. And this month, we’ll startwith a quiz question!

What single sailplane controlsurface causes a clean directionalchange?

Aileron?Rudder?

Flap?Elevator?

Aileron is not correct. It causesthe sailplane to roll on the axis ofits fuselage, no directionalchange, clean or otherwise.

It is not Rudder, either! WhileRudder does cause a directionalchange, calling it clean is astretch, because in fact it alsocauses roll and yaw, as in spiral-ing toward gravity’s source.

If you chose Flap, you’re gettingclose! Flap does cause a prettyclose to clean directional changebut, in fact, while it does cause

some ‘up’ nose pitch, it mostlycauses the entire model to changeits place in space. Sort of likechanging the model from oneshelf to another.

If you chose Elevator, then yougot it! Whether we are talkingmodel or full size, flying wing,biplane, conventional tail or V-tail, it’s Elevator that makes thesailplane’s nose go cleanly up ordown. That’s a directionalchange! Now to make the sail-plane go right or left, the model’sattitude has to first be changedusing aileron or rudder; then the‘turn’ is executed with elevator,and ended by using aileron orrudder to bring the model’sattitude back to level to end the‘turn.’

So having said all that, why was Iable to control my Pike Superiorwith little problem when myelevator servo unplugged imme-diately upon release from myhand? Even though I had littleproblem while working lift offthe winch, little problem bringingit in for a smooth controlledlanding?

Sure I am a superior RC sailplanepilot, but without elevator, as inthe elevator was stuck in neutral,I was not in complete control ofmy sailplane.

Here’s what happened. I flew thefirst round with no problem, butthe night before I had beenfutzing with installing ballast intothe fuse and must have loosenedthe elevator servo plug into theRX. The second launch, I pumpedup tension on the winch line,then let the Pike spring out of myhand. That force was enough toshift the Rx backwards anddislodge the elevator’s plug. Theelevator stayed at neutral and themodel went up the line. It didn’ttake long to note that the elevatorwas not responding, and that Icouldn’t dip into the bucket tobuild speed for the zoom release,so I simply let off the winch andthe Pike floated level off the line.

It was clear that rudder, aileron,and flaps were working just fine,just no pitch from elevator.Considering my appreciation forwhat I feel is maybe one of thetop two molded TD ships onearth today and the love I havedeveloped for it, you can imaginemy shock and awe at the pros-pect of losing that plane.

It was clearly time to engagebrain, and quickly. Did I mentionthe wind was blowing 15mphsteady with gusts up to 25mph?That kind of complicates things,even WITH elevator function!

As I mentioned earlier, I hadtested rudder and aileron and,while they were doing what theydo best, the Pike was starting tofollow its nose down, so I had totry something else. I rememberedthat with landing flap, downelevator compensation keeps thenose from pitching up, and themodel in general from rising. So Itried pulling some flap, and thePike pitched up sharply to a stall!

Okay so I also had pitch control!However it was very touchy; aslight amount of flap stick causedpretty radical up pitching action,so it took some reprogrammingof my left thumb to get my Pikeunder smooth control. Course allthat wind didn’t make it easy, butthe important thing was itworked!

I flew it around getting the feel,and found that there was a lot oflift coming through, so getting itdown was work. After landing it,I realized that I landed at about aminute thirty seconds, instead ofthe 5 minute task the roundcalled for, which put me well outof the winner circle. If I wouldhave understood what did what,with all the lift that was present,I’d have had no trouble makingmy time, even if it would havebeen unlikely that I’d have acedthe landing without elevatorcompensation.

Next time out at the field, when

May 2004

your plane is about four dumb thumbs high, leave your elevatoralone and fly around just using your flap stick for pitch control.Get comfortable with it and practice, without using elevator. Userudder and flap, use aileron and flap. I guarantee that you willhave a lot better understanding of what does what, when it comesto your control surfaces.

Next trip? Traveling the contest trail with the Pike Superior.• • •

FAI News 04/04Fédération Aéronautique Internationale

The World Air Sports Federation

What follows is information about FAI, and excerpts from their newsletter, thanks to a forward byB2.

Nice to know

The FAI Recommended Museum Program recognizes museum collections of an aeronauti-cal nature which contribute to furthering the education of the public in the history andpractice of air sport, aeronautics and astronautics.

<http://www.fai.org/education/museums/ Information / Conditions<http://www.fai.org/press_releases/2004/documents/fai_rec_museums.pdf

Links

FAI Homepage <http://www.fai.org>Sporting Calendar <http://events.fai.org>World Records <http://www.fai.org/records>

About FAI

The Fédération Aéronautique Internationale (FAI), the world air sports federation, wasfounded in 1905. It is a non-governmental and non-profit making internationalorganisation with the basic aim of furthering aeronautical and astronautical activitiesworldwide. Ever growing, FAI is now an organisation of some 100 member countries. FAIactivities include the establishment of rules for the control and certification of worldaeronautical and astronautical records. FAI establishes regulations for air sporting eventswhich are organised by member countries throughout the world. In achieving these goals,FAI brings together people who take part in air sports from all over the world.

Maynard L. HILL honoured

On 15 August and 27 October 2003, the FAI-News reported on the World Record set byMaynard L. HILL and his crew as their Model Plane crossed the Atlantic Ocean; thisoutstanding performance has been honoured by Aviation Week & Space Technology.

At the beginning of February, the Aviation <http://www.aviationnow.com/ Week &Space Technology Magazine presented its 47th annual Aeropspace “Laurels” selections.Each year, the magazine’s editors nominate individuals and teams who made significantcontributions to the international field of aerospace during the previous year.

In the category “Aeronautics / Propulsion”, Maynard L. HILL has been honoured for“designing and being the first to fly an 11-lb model aircraft across the Atlantic Ocean, re-creating the flight of Alcock & Brown. Hill displayed remarkable tenacity in achieving thisgoal, making such a small craft have both the range and reliability required while on ashoestring budget, and overcoming poor weather and other hazards. Hill’s lifelong effortsin support of model aviation have inspired generations of people attracted to aerospace”.

R/C Soaring Digest

Although a million articleshave been written about

batteries (and I’ve read most ofthem) they usually contain a lotof theory and not enough “howto.” This is a simplified (I hope)explanation of the best way tofeed and care for your transmitterand receiver packs.

You need to think of chargingyour packs in three separateways. When you get a new pack,whether in your new radio gearor a replacement pack, you needto perform a FORMING charge.Once you have successfullyformed the battery a BEST chargeis what you should use most ofthe time. An EMERGENCYcharge can be used occasionally ifyou get caught with a low pack ata time when you really want tofly. Lets talk about each of thesecharge types so that I can clearlydefine what they are and howthey are different.

New packs come from themanufacturer uncharged andoften will not take the first chargevery well. A number of pilotshave lost airplanes to new packsdying quickly because theydidn’t take that first charge well.So a FORMING charge is re-quired for all new packs. It is aslow deep charge best performedby charging at approximately10% of the pack’s rated capacityfor 14 to 16 hours. (For a typical600mah pack this would be 60ma. Your charge rate doesn’thave to be this exact figure butshould be within plus or minus50%.) This can be done with thewall wart or a specialized charger– your choice. Feel the packoccasionally and see if it isgetting warm. It should get warmtoward the end of the time limit.If it doesn’t get warm stop thecharge anyway, discharge thepack, and do another formingcharge. You should do at leastone forming charge and probably

a maximum of three. It is danger-ous to fly a pack after only oneforming charge. Trying to fastcharge a new pack before prop-erly forming it can make itdifficult to fast peak chargereliably in the future and seri-ously shorten its useful life.

It is also good to do a formingcharge occasionally throughoutthe life of a pack. Nicads have atendency to charge and dischargeunequally when fast charged andthey can slowly form a ‘weak’ cell(one that is not fully chargedeven though the pack ‘peaks’ inthe other cells). The formingcharge will level up the charge inall cells and keep the packcapacity up. I suspect that it isthis uneven cell level that is oftenmisidentified or referred to as‘memory effect’. In any case aforming charge every 6 monthsor so will keep the pack in sync.

Both the BEST charge and theEMERGENCY charge are consid-ered fast charges. They shouldonly be performed using a goodpeak-detecting charger that willshut off automatically. When thecharger shuts off the pack shouldbe noticeably warm. If it is hotbut you can close your handaround the battery it is still okbut not ideal. If it is still cool youmight want to be suspicious as towhether it accepted a normalcharge or not.

The BEST charge uses a peakdetecting charger set at about25% to 35% of the pack’s ratedcapacity. (For a typical 600mahpack this would be 150ma to210ma.) For a full charge the peakcharge should take about fourhours and then trickle charge fora total time of 5 to 6 hours. Mostgood peak chargers automaticallyswitch to a trickle charge after thepack peaks. This brings the packup to full capacity in a reasonablyshort amount of time and pro-

vides good longevity for the cells.

The EMERGENCY charge is forwhen you really need to get analmost depleted pack into actionas soon as possible. This chargeuses a peak detection charger setat 200% (nicads) or 100% (nimh)of the pack’s rated capacity. (Fora typical 600mah pack this wouldbe 1200ma or 1.2 amps for thenicads or 600ma-0.6 amps for thenimh pack.) This is not danger-ous and doesn’t hurt the cells ifyou have a good peak detectingcharger and your packs are ingood shape. It really doesn’tprovide a full charge since thecells don’t have time to absorband diffuse the charge through-out the cells. But it provides whatlooks like a full charge and plentyof flying time. For nicads theemergency charge should takeabout 30 minutes from empty tocutoff. Nimh packs will take 60minutes. Normally, it will bequicker than this since you won’tstart with totally depleted cells.

Don’t run your nicads or nimhsdown for storage. Just put themaway in a cool dry place and do aforming or best charge every oneto two months. If you forget andthey go depleted no harm will bedone, just be sure to best chargeand cycle them once the next timeyou go to use them. The absoluteworst thing you can do to batter-ies is to leave them on any socalled “trickle” charger for long(weeks) periods of time. It killsthem. (I don’t care what theadvertising says. Trust me onthis.)

A trick you should keep in mind,even if you never use anythingbut a wall wart to charge yourbatteries, is that when a pack oncharge gets warm it is done.Packs do not warm while theyare being charged. They don’twarm until they are full. Whenthey are full the charge current

The Voodoo Theory of Battery Maintenance(The Basics of Rechargeable Battery Care.)

by Rick [email protected] 2002

May 2004

begins getting converted to heat and thus the pack warms up.

Remember:

• Forming Charge = 10% of rated capacity (trickle charge) for 14 to 16 hours (i.e., a 600mah pack wouldbe charged at 60 milliamps – 0.060 amps

• Best Charge = 25% of rated capacity peak detected plus 10% charge for 3 to 4 hours (i.e., a 600 mahpack would be charged at 600 milliamps – 0.600 amps.)

• Emergency Charge = 100% (nimh), 200% (nicad) of rated capacity using a good peak detectingcharger (i.e., a 600 mah nimh would be charged at 0.6 amps. A 600 mah nicad would be charged at 1.2amps.)

• Never trickle charge for long periods.

Whether or not you agree with my exact charge rates I think you will agree that viewing charging in thisway will add to the life of your cells and avoid a lot of battery problems during your flights.

• • •

E-MAILOur Contest Winches

from Dave [email protected]

One thing for US winches, the drum design is actually a little tricky. If it’s too narrow the linewill pile up and start loading down the motor at the top of the launch. If it’s too deep, you

don’t get enough pull at the start. Both the Rahm and the McCann winch drums do a good jobof compromising on this. Don’t know about others but it’s something to consider for U.S. TDcontests.

Our contest winches have 3 large 12 V batteries in parallel for the winch and two 6V in parallelfor the retriever. Large copper knife switches for cutouts. We also replaced the bushings withthe Real Balls bearings and they made a big difference. You also need to replace the brushes toget the most out of them as well.

All of this adds to weight so we’ve gone with trailers which can be towed to the field and thenpushed out to the setup area. A bit of work to build them but they give years of service this way.

Industrial strength winch picture attached for reference. The tool box on the trailer is veryhandy for landing lanes, spare parts, tapes, line, tools, etc. A staked down hoop about 10 ft. outfrom the retriever is essential to keep it working properly.

THE WINCH SCENE

R/C Soaring Digest

THE WINCH SCENEE-MAIL

Australian Winches

from [email protected]

We were impressed by the Australianwinches because each was individu-

ally made - no two were the same. Somewere low slung, others lifted the line offthe ground, some had removable wheels,some had large diameter drums... All wereportable. There are a lot of ideas to begarnered from them, as can be seen by thethree examples we’ve included with thismessage. (The images are relatively lowresolution, 150 dpi, and 50% JPG compres-sion.)

Spool diameter is a dimension which canbe whatever the designer wants. You canuse braided line on any of the winches wesaw. There’s no reason separate retrieverscannot be used. The chain or sprocketbrake is a viable option for winches notattached to retrievers.

Seattle Area Soaring Society

SASS (Seattle Area Soaring Society) hastheir club winches stored in a shipping

container on the field. The winches are mounted ontrailers which can be towed with a hitch, but therehave been times when it’s been dragged across thefield by hand. Winch, retriever and extra batteries areall on the trailer, along with useful tools, leathergloves, etc.

May 2004

WINCH SAFETY TIPby Dave Garwood

One of the great horror shows of winch launching is a “runawaywinch,” a condition where the winch motor remains energized

after the pilot removes his foot from the footswitch. This can happenmore often than you might think, because a common failure mode ofthe automotive current-switching solenoids is “contacts weldedtogether” and the high-amperage current continues to flow to themotor, even though the low-amperage control circuit is now openwith the pilot NOT tapping the foot switch.

A runaway winch can pull a sailplane into the ground at high speedin a short time. When this happens, it takes a quick-thinking andagile pilot to pull up and disengage the tow ring, and even so, it’s ahigh-adrenaline moment, the sailplane is launched prematurely,possibly at an unusual attitude, while the winch still furiously pullsin line, creating the rat’s nest of the season on the reel. On a lightlybuilt sailplane, a runaway winch can quickly fold the wing. Peoplewho have witnessed this event do not forget it easily.

I’ve seen three strategies used to reduce the hazard:

1. Install a cut-off switch in the high-current circuit. Suitable switchesare available from boating and recreation vehicle suppliers.

2. Install TWO solenoids in the high-current circuit. They are wired inseries, so that if one welds itself closed, the other may continue tofunction and open the high-current circuit and stop the motor whenthe footswitch is released.

3. Replace the solenoids each flying season. New solenoids are lesslikely to fail than old solenoids (less accumulated damage frominternal arcing, return spring stronger).

For maximum safety, it makes sense to incorporate all three strate-gies, and to have each pilot using the winch, practice using the cut-offswitch. Does this “extra” equipment seem costly? Consider the valueof the sailplane you are launching.

“Safety is No Accident”• • •

Safety Tip

from [email protected]

One more switch thatcan weld shut is the

foot switch. We had thishappen at a Wednesdaynight fun fly last summer.Folded the outer wingpanel of non-ARF Bird ofTime. Everyone thought itwas the solenoids, but thewinch shut down as soonas the foot switch wasunplugged.

Andrew Mileski has a duallight system described inone of his links whichshows when the solenoidsare operating correctly andwhen they’re not. UsesLEDs. Otherwise onesolenoid can already bewelded shut and goundetected until thesecond does the samething.

Andrew Mileski:http://isoar.ca/

~andrewm/rc/winch

An Old Winch

by Jerry [email protected]

This winch was manufacturedby Ted Davey at Davey

Systems Corp. in PA some 40years ago. It was state of the artin its time. It has an angel ironwelded frame, drum mounted ona live axle, and is belt driven by acar starting motor.

I still use the winch today if Idon’t have to carry it too far. Thewinch frame and motor weighs38 lb.; the battery weighs 51 lb.

R/C Soaring Digest

E-MAILSingle Winch Design

from Gordy [email protected]

There is a reason that we have settled on a single winch design(90%). Actually a bunch of reasons, uniformity being the most

important. When I show up at a contest, I know what the winch willdo, how the line reacts, how the brake works, how much my wingswill be loaded using the same pulse rhythm as I do at home, inDallas, in Lancaster or in Visalia.

Safety is the next big factor. I know what to do with every winch thatI come across if the solenoids get stuck, or the line gets crazy.

Everyone who gets enough experience and interest in the hobby to beready to have their own winch, dreams of the ‘ultimate winch’:electronic braking, electronic variable speed and torque control, loadsensing, etc. Then, of course, the line is next thing to be ‘improved.’We quest for some spectra fibre, or kevlar line, which weighs noth-ing, creates no drag, doesn’t tangle and never breaks.

But in the end, we realize that nothing else is ‘needed’ because all weneed is lift, the same lift at every place we fly.

For awhile we had belt drives, special motors and different drumcenter shapes and diameters. The NATS used a super poweredversion of our ‘standard’ winches and that resulted in hundreds ofsailplanes being destroyed over the years. They were works ofengineering masterpieces, a little too good.

Competition soaring guys, that is F3B and F3J pilots, all have astandardized FAI spec’d winch, made by one guy in NZ. No retriev-ers, because FAI doesn’t allow them. I flew in Sydney andMelbourne, and I saw 23 winches and every one was identical to theothers, whether the guy was flying a Spirit RES or a Pike Superior.Clubs are careful to direct new members to get or build a ‘standard’winch.

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.

To kick it off this month,we’re sharing several of oure-mail messages and anarticle written by DaveGarwood. We encourageanyone who has a hint, tip,photo or suggestion on thesubject of winches to sendit to <[email protected]>.

Judy [email protected]

E-MAILThoughts on Australian Winches

from Gordy [email protected]

Australian winches are F3B winches, completely different than anything used in the USA exceptfor F3B task flying. They use them for winch powered F3J contest launching over there, too.

So it is important to point out the differences:

No belt braking which can allow line to be released back into the air for ‘kiting’ launches. Insteadthey use a chain brake, or pin lock system which does not allow any release of line, unless the brakeis undone for bringing the parachute back for relaunch.

No chance of using a retriever as is the norm in the USA (except for Man On Man TD comps).

Monofilament line instead of our braided line. Theirs stretches a lot which gives a more slingshotrelease.

Smaller diameter drum than the USA winches and the motor is restricted with resistors to limit thewinch power to a very specific and uniform speed and torque.

May 2004

Vol. 21, No. 5

Documents

Transcript of Vol. 21, No. 5