Page 1September 2002

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R/C Soaring DigestPage 2

ABOUT RCSD

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TheSoaring

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

Figure 1. Movement of the stagnation point along the spanof a swept back wing, exaggerated.

Direction of flight

ß, sweep angle

Right semi-span

Root

Tip

Figure 2. Alignment of wing sections to local flowby means of geometric twist, exaggerated.

Direction of flight

ß, sweep angle

Right semi-span

Root

Tip

Twist Distributions forSwept Wings, Part 3

In Part 1 we defined and provided ex-amples of lift distributions. Part 2 exam-ined stalling patterns of various planformsand introduced the notion that sweep angleand coefficient of lift can affect the angle ofattack of outboard wing segments. Threeconsistent themes have been underlyingthe discussion thus far: (1) achieve andhopefully surpass the low induced dragexemplified by the elliptical lift distribu-tion without creating untoward stallcharacteristics, (2) reduce adverse yawcreated by aileron deflection withoutadversely affecting the aircraft in pitch,and (3) maintain an acceptable weight tostrength ratio. In Part 3 we will describe amethod of achieving the second goal.

Sweep and twist

Figure 1 (reprint of Figure 8, Part 2)shows the increasing upwash

which affects outboard segments of aswept untwisted wing as it produceslift. Although exaggerated in thediagram, the overall tendency is clearand does appear in practice.

While there are several ways ofreducing the tendency for the wing tipto stall, like careful consideration ofairfoils or addition of wing fences,there are advantages to impartingsome twist to the wing in the form ofwashout (leading edge down).

Figure 2 illustrates the case where thewing is twisted such that each wingsegment has the same angle of attackas related to the oncoming air flow.Since the increasing upwash ahead ofthe wing is directly proportional to theamount of lift produced by inboardwing segments, this illustration isobviously accurate for only one aircraftvelocity and attitude. The generalconcept is, however, very important.

Vectors

Mass, length, pressure and time can bedefined by single real numbers. Thelength of a spar for a two metersailplane, as an example, may be 39inches. As there is a unit of measure-ment, inches in this case, the sparlength is a scalar quantity. The numberwhich provides the magnitude, 39, isconsidered a scalar.

Force, on the other hand, has both amagnitude and a direction, and istherefore classified as a vector quan-tity. A five pound brick resting on atable in a gravitational field may berepresented as shown in Figure 3A and3B. If another five pound brick isplaced on the first brick, the situation

can be depicted as in Figure 3C. Notethat the arrowhead always indicatesthe direction of the force, while thelength of the line indicates the magni-tude of the force.

Figure 4 provides an illustration of thevectors involved in sustained, constantvelocity flight. The upper illustrationdepicts a powered aircraft in straightand level flight. The weight of theaircraft, W, is counteracted by thegenerated lift, L. The drag, D, iscounteracted by the generated thrust,T. There is a single vector, R1, whichcan represent the combined lift anddrag forces, and a single vector R2which can represent the combinedthrust and weight vectors.

Direction of flight

Figure 1. Movement of the stagnation point along the spanof a swept back wing, exaggerated.

Direction of flight

Figure 2. Alignment of wing sections to local flowby means of geometric twist, exaggerated.

Page 5September 2002

brick, five pounds

A

B C

Figure 3. Examples of vector quantities.

L R1

DT

WR2

L

D

R1

R2 ( = W only)

Figure 4. Force vectors on powered and unpowered aircraftwhich are otherwise identical.

L R1

DT

WR2

R2 ( = W only)

A

B

C

D

LR1 Ti

These two resultant vectors are calcu-lated by constructing a parallelogramusing the two known vectors. R1 and R2are of equal magnitude and oppositedirection in this case, and the aircraft istherefore flying at a constant velocity. Ifthrust is increased, as shown in Figure4B, the T vector length increases, indicat-ing increased thrust, thus changing theshape of the parallelogram. R2 becomeslonger and rotates forward. The dragforce D then increases as the aircraftvelocity increases. Once drag and thrustare equal, the aircraft velocity will onceagain be constant.

The lower illustrations in Figure 4 depictthe case of a powerless aircraft of thesame design. It is in gliding flight. InFigure 4C the aircraft is moving forwardat a constant velocity and slight down-ward angle. There is no engine togenerate thrust so the weight W aloneforms R2. Now consider the flight pathand note that the lift vector is ninetydegrees to the air flow and the dragvector is parallel to the air flow. (This isthe same as seen in the previouslydescribed powered example.) Theresultant vector, R1, is of exactly thesame magnitude as R2 and in the oppo-site direction, so the aircraft is flying atconstant velocity.

If the nose of the glider is pointed moredownward, as in Figure 4D, the flightpath rotates in relation to the weightvector. The lift and drag vectors continuebeing perpendicular and parallel to theair flow, respectively, and so they rotateas well. R1, the resultant of the lift anddrag vectors, rotates forward as onewould intuitively expect. There is nowan “induced thrust,” Ti, which willaccelerate the aircraft until the drag forceincreases to exactly counter it. When R1equals the weight (R2), the aircraft willonce again be traveling at a constantvelocity.

Induced thrust

We’ve used the term “induced thrust” inthe previous paragraph, and there aresome readers who may not believe thatsuch a thing exists, despite having aknowledge of “induced drag.” Perhapsone of the best examples of “inducedthrust” is the action of a winglet. A verylarge number of aerodynamics textsdescribe winglets in detail, so we will notdo so here. What we want to bring intofocus is the production of induced thrustby the winglet.

brick, five pounds

Figure 4. Force vectors on powered and unpowered aircraftwhich are otherwise identical.

R/C Soaring DigestPage 6

L

D

Air flow

Figure 5. Induced thrust, Ti, generated by winglet.

Tiwinglet MAC/4

αR

Neutral aileron

Down aileron

Up aileron

Figure 7. Generalized representation of the direction and strength of forces when the outboard aileron of a twisted swept wing is deflected.

Direction of flight

L

D

D

L

R

R

L

D

R

The upper illustration of Figure 5shows a wing from the rear, with thewinglet structure defined by phantomlines. The air flow is shown travelingoutboard along the bottom surface ofthe wing and inboard across the uppersurface. The velocity of this movementis generally greater near the wing tipas shown by the lengths of the lines.

The air flow outboard of the wing tipis very close to circular, but remember,the free stream velocity is added to thiscircular motion, so the resultant airflow meets the winglet at an angle. Thelift and drag vectors are shown in thelower illustration. Note the nowfamiliar rotation of the resultant inreference to the winglet MAC/4 axis.(MAC/4 is the 25% chord point of themean aerodynamic chord and is theorigin for the winglet lift and dragvectors, just as for any wing segment.The MAC/4 axis and the yaw axis arein parallel planes in the presentedexamples.) The vector Ti is the inducedthrust generated by the winglet.

We can extend the notion of “inducedthrust” from a winglet to the outersegment of a lifting swept wing.Consider Figure 6A. In this case, anairfoil is generating some lift while theair flow is precisely horizontal. This isa situation identical to that when anairfoil with a zero lift angle of somenegative value is set in a wind tunnelat zero degrees angle of incidence tothe air flow. Note that the lift vector isvertical (ninety degrees to the air flow)and the drag vector is parallel to theair flow. The resultant is rotated at anangle behind the vertical quarter chordaxis. In the wind tunnel, as the airfoilangle of attack is increased, the liftvector remains perpendicular to the airflow, the drag vector remains parallelto air flow, and the axis remainsvertical, perpendicular to the air flow.

In Figure 6B, the air flow is comingfrom below at an angle of five degrees.The lift and drag vectors have rotatedto match the air flow, and the resultantcoincides with the vertical MAC/4axis. Figure 6C shows the case wherethe air flow is coming up at an angle often degrees. The lift and drag vectors(and the resultant, of course) haverotated forward of the axis.

Figure 6D shows two situations whichtake place at an air flow angle of 15degrees. We’ve shown a single lift

Figure 5. Induced thrust, Ti, generated by winglet.

Direction of flight

Figure 7. Generalized representation of the direction and strength of forceswhen the outboard aileron of a twisted swept wing is deflected.

Page 7September 2002

A.

Figure 6. Rotation of lift vector caused by upwash, anda single case of the effect of twist on that rotation.

B.

D.

C.

E.

Direction of flight

L

D

R

D

L R

L

D

R

L

D1D2

R1

R2

L

D

R

vector and two drag vectors. If thedrag is low, the resultant (R1) remainswell ahead of the axis. If the drag isexcessive, however, the resultant (R2)rotates behind the axis. This is animportant concept to keep in mind.

The case of the outer segment of atwisted swept wing is shown in Figure6E. The air flow is coming up at anangle of ten degrees and the airfoil isset at an angle of incidence of minusfive degrees. As the wing section“sees” an angle of attack of fivedegrees, the lift is of the same magni-tude as in Case 6B, but the resultant isrotated to a direction nearly identicalto that of Case 6C.

It may be helpful to consider the outer

portion of a swept back wing to be a“flattened” winglet, as the effects ofthe two are essentially identical.

Induced thrustand aileron deflection

And now the part you’ve been waitingfor... Take a look at Figure 7. Thisillustration is of the outer segment of atwisted swept back wing with aileroninstalled.

When the aileron is in neutral position,the resultant vector is directly over theprojected yaw axis.

When the aileron is deflected down-ward, the lift is increased substantially.The resultant is rotated forward of the

axis. This induced thrust actuallypushes the wing forward.

When the aileron is deflected upward,the lift vector decreases in magnitude,reducing the induced thrust. (If theaileron deflection is large enough, thelift vector changes direction.) Theresultant of the lift and drag vectorsrotates behind the axis, pulling thewing backward.

In an aileron induced turn, adverseyaw in a swept wing planform can bereduced or eliminated entirely bymeans of manipulating the lift anddrag vectors of the outer portion of thewing through appropriate wing twist.

When the wing tips are lifting down-ward, aileron deflection acts to reduceadverse yaw. This case can be envi-sioned by inverting the vector diagramfor a (normal) upward lifting wing.We’ve done the inverting and placedthe results in Figure 8.

Reducing adverse yaw

Figure 9 examines the case of theunswept wing with an elliptical liftdistribution with aileron deflection fora left turn. (This diagram is a reprint ofFigure 5 from Part 1.) The ailerondeflection increases the drag of thewing semi-span having the downwarddeflected aileron and decreases thedrag of the wing semi-span having theaileron deflected upward. This causesa roll to the left and a yaw to the right.This adverse yaw requires a compen-sating rudder deflection.

Figure 9 also examines the case of theswept wing which utilizes a liftdistribution which is not elliptical butwhich does allow for coordinatedturns by eliminating adverse yawthrough induced thrust. The wingsemi-span with the upward deflectedaileron generates more drag than thewing semi-span with the downwarddeflected aileron. The wing rolls andyaws to the left. In this case no com-pensating rudder deflection is re-quired.

Swept wings without a vertical sur-face, like many of the Horten designs,can use wing twist in conjunction withsweep to produce coordinated turns,particularly at low speed (high CL), aswhen thermalling. There may be somedisadvantages to this methodologywhen flying at high speed (low CL),

Direction of flight

Figure 6. Rotation of lift vector caused by upwash, anda single case of the effect of twist on that rotation.

R/C Soaring DigestPage 8

Direction of flight

Figure 8. Generalized representation of the direction and strength of forces when the outboard aileron of a downward lifting wing segment is deflected.

Neutral aileron

Up Aileron

Down aileron

L

D

R

RL

D

D

RL

but the detrimental effects can be con-trolled by careful design of the ailerons,including their location, size, anddeflection angles.

Coming in Part 4

The next installment will devote somespace to the relationships betweenaileron configurations, wing lift distribu-tions, and adverse and proverse yaw.And now that we have a method ofreducing or eliminating adverse yaw, wecan back up a bit and take a look at whatwing sweep, increased upwash and wingtwist can do for the first of those threepoints we keep mentioning, our quest toreduce induced drag.

_______________

Ideas for future columns are alwayswelcome. RCSD readers can contact usby mail at P.O. Box 975, Olalla WA98359-0975, or by e-mail at<bsquared@appleisp.net>.

References:

Bowers, Al. Correspondence within<www.nurflugel.com> e-mail list,early 2002.

Galè, Ferdinando. Tailless tale.B2Streamlines, Olalla WashingtonUSA, 1991.

R/C Soaring Digest556 Funston Drive

Santa Rosa, CA 95407

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Direction of flight

Figure 8. Generalized representation of the direction and strength of forceswhen the outboard aileron of a downward lifting wing segment is deflected.

Page 9September 2002

Figure 9. Lift and drag profiles for an untwisted rectangular wing with aileron deflection for left bank, no differential (upper), and for a twisted

swept wing with washout, no differential (lower).

roll to left

yaw to right

yaw to left

roll to left

Gullberg, Jan. Mathematics: from the birthof numbers. W.W. Norton & Co., NewYork, 1997.

Hoerner, Dr.-Ing. S.F. and H.V. Borst.Fluid-dynamic lift. Hoerner fluiddynamics, Vancouver WashingtonUSA, 1985.

Horten, Dr. Reimar. Lift distribution onflying wing aircraft. Soaring June 1981,pp. 40-42.

Jones, Bradley. Elements of PracticalAerodynamics, third edition. JohnWiley & Sons, New York, 1942.

Jones, Robert T. Wing theory. PrincetonUniversity Press, Princeton NewJersey USA, 1990.

Kermode, A.C. Mechanics of flight.Pitman, London, 1980.

Masters, Norm. Correspondence within<www.nurflugel.com> e-mail list,early 2002.

McCormick, Barnes W. Aerodynamics,aeronautics, and flight mechanics.John Wiley and Sons, New York, 1979.

Nickel, Karl, and Michael Wohlfahrt.Tailless aircraft in theory and practice.American Institute of Aerodynamicsand Astronautics, Washington D.C.,1994.

Shevell, Richard S. Fundamentals offlight. Prentice-Hall, Englewood CliffsNew Jersey USA, 1983.

Simons, Martin. Model aircraft aerody-namics. Argus Books, HemelHempstead Great Britain, 1994.

Smith, H.C. “Skip.” The illustrated guideto aerodynamics, second edition. TABBooks, Blue Ridge Summit Pennsylva-nia USA, 1992.

The White Sheet, Spring 1986, No. 36. SeanWalbank editor. White Sheet RadioFlying Club, Dorset/Somerset GreatBritain.

n

yaw to right

Figure 9. Lift and drag profiles for an untwisted rectangular wing withaileron deflection for left bank, no differential (upper), and for a twisted

swept wing with washout, no differential (lower).

R/C Soaring DigestPage 10

HAVE SAILPLANE, WILL TRAVEL!

By Tom H. Nagel904 Neil Ave.

Columbus, OH 43215tomnagel@iwaynet.net

M slope in Platteville, Wisconsin.

The U-2 begins its plummet from the “M” Mound.

As Close To Normal AsI’ve Ever Been

orRoiling on the River

Herewith another tale of woe andintrigue as the Heath-Nagel clan

reports back from its travels to scenicand exotic Iowa. That’s right HSWTfans: after all ten of the participatingHeath-Nagel clan honchos put theirheads together, using the latest 21stcentury technology and the magic ofthe internet, the best we could come upwith for the 2002 Mass Migration wasIowa. And you know what? It wasn’tso bad. I even got to fly, for about 15seconds, more or less.

This was a bittersweet reunion, thefirst clan gathering since the passing ofour patriarch William T. Heath. Lastsummer’s trip to Ludington was hislast vacation, and I think that themorning he and I spent flying a ZagiTHL over the dunes at Manistee StatePark was just about his last outing; hewas hospitalized shortly after wereturned from vacation and died in

early September. It has taken me awhile to start writing again.

Brother-in-law Mike Heath found theplace: McGregor Iowa, a tiny Victorianriver town, right across the Mississippifrom Prairie du Chien, Wisconsin, andjust a little south of the Minnesota stateline. And Greg Smith of slopeflyer.comclued me in on one of the two flyingsites I visited on this trip.

We had four folks traveling from Ohio,and ten clan members, eight boats, andfive cars in all when we assembled insouthern Wisconsin for the finalassault on McGregor, Iowa. It looked alot like The Beverly Hillbillies GoKayaking as we rolled across the milelong bridge and causeway, over theupper Mississippi and into McGregor.As it turns out, that was pretty muchappropriate. McGregor Iowa looks a

Page 11September 2002

One of the many unique shops in downtownMcGregor Iowa: River Junction, a store entirelydevoted to clothing and supplies for Civil Warre-enacters. Upstairs is the McGregor branch of

the well known law firmDewey, Cheatam & Howe.

Commemorative plaque at the base of theM Mound in Platteville, Wisconsin.

Vista from the top of the MMound in Platteville.

lot like West Virginia, as if someonehad poured a few million dollars intothe New River Gorge and yuppified it,adding B&B’s, boutiques and antiquestores. Lots of people had canoes andkayaks on their cars. Others werehauling power boats of every descrip-tion. The only thing missing waswhitewater. Instead there were twobroad navigation channels and a mazeof bayous and small channels.

Steep limestone bluffs line both sidesof the valley. The railroad runsthrough the middle of town, housesare crowded together between thebluffs and the river, and the not-so-bigmuddy is convoluted with oxbows andback waters and wetlands that makeup the Upper Mississippi River

National Wildlife and FishRefuge, a 260 mile longnetwork of natural areas inWisconsin, Illinois, Iowa andMinnesota.

The first soaring connectioncame when we checked intothe Little Switzerland Bed andBreakfast. The host gave us acopy of the official State ofIowa Transportation Map,which has a picture on thecover of Carl Bates of nearbyClear Lake, Iowa, who, in1898 at age 14, built and flewthe first man-carrying gliderin Iowa. The region’s check-ered aviation history alsoincludes the crash and deathof Buddy Holley and the BigBopper. And now I was intown with an RC sailplane.

We had arrived under a

thoughtfully built a large triangularconcrete observation deck that juts outover the heavily wooded gorge,looking east over the valley.

It was late afternoon. Winds were outof the east at 15 to 20 mph. AmericanBald Eagles were sloping up and downthe river along the bluffs. There wasn’ta park ranger in sight. And my sail-plane and transmitter were back intown. I settled for watching eagles andwishing I was flying with them.However, it was clear that this over-look has great sloping potential.Landing, however, would be some-thing else.

Because of logistic considerations onthis trip, the only plane I had brought

clearing sky, as a day long drizzleended. As soon as we got checked in atthe B&B, Mike and the kids decided totake canoes and kayaks out on theriver. It felt a little late and a littlewindy to me, so after we set thevoyageurs on their way, I collected thewife and grandma, and we drove up toPike’s Peak State Park for a look at thevalley, and the next soaring connec-tion. Pike’s Peak State Park is namedafter Lt. Zebulon Pike, who came upthe river in 1805 to survey the Missis-sippi, and suggested a fort be locatedthere. He later named some hilltop inColorado, too, I think. But anyway, thespot he picked in Iowa is the highestbluff overlooking the Mississippi, agood 500+ feet above the junction ofthe Wisconsin River with the Father ofthe Waters. The Iowa DNR has

R/C Soaring DigestPage 12

View of the Mississippi from the overlookat Pike’s Peak State Park, Iowa. Flying here

is easy. Landing is hard.

Nancy rides the carp at Prairie duChien, Wisconsin.

This column is dedicated tosoaring vacations. If you have a

favorite sailplane saga, considerwriting it down for RCSD. If youare planning a vacation thatincludes your plane and transmit-ter, consider making notes as yougo, and working up an article later.Take photos. Collect maps. Andsend your story to Tom Nagel attomnagel@iwaynet.net for gentleediting and suggestions.

Tom

along was my trusty RPVI U-2, a chunky all EPP six footerwith a fast RG-15 airfoil. Itbreaks down and travels well,almost indestructible in abundle not too much biggerthan a loaf of French bread. Ilooked at the Pikes Peakoverlook a couple of moretimes during the week. Therewas plenty of wind, and theU-2 would have undoubtedlyflown well in the same liftbeing used by the eagles,

During the week we found a nice barand restaurant called Mulligans, acrossthe river in Prairie du Chien. Thattown is the oldest one in Wisconsin,and was founded in 1673 by PereJacques Marquette and Lois Jolliet whocame down the Wisconsin River andbecame the first Europeans to see theMississippi River. (I think they wereprobably lost, on their way home fromLudington, but I’m not sure aboutthat.) Marquette, with his typical Gallicsense of humor, named the town afterFox Indian chief whose name trans-lated into French as “dog.” The townbecame known as Prairie of the Dog, orPrairie du Chien. Today the town hoststhe mid-summer Prairie Dog BluesFestival. Other attractions include thesite of the Battle of Prairie du Chienfrom the war of 1812, the only battlefought in Wisconsin, an immenseCabela’s Outlet Store (good source formonofilament winch line), and theannual Carparee, a sort of Carp Rodeo.The town also boasts the world’slargest hand carved wooden carp,

hawks and buzzards. But landing theheavy and fast flying U-2 in tightquarters among a flock of tourists justlooked too risky. A Zagi, MOG or RedHerring, or anything that could belanded softly in the bushes would dojust fine. I’d brought the wrong plane.

Here’s a couple of interesting thingsabout Pike’s Peak State Park: it is theonly place I know where you can seeone of the smallest bird in NorthAmerica, the Ruby Throated Hum-mingbird, within about 50 yards of oneof the biggest, the American BaldEagle. Pikes Peak hosts flocks of bothhummingbirds and eagles. And bats –boxes of little brown bat, and bath-rooms full of bats, too. The bats havetaken over the eaves of the park’sbathrooms. There is lots of flying goingon at Pikes Peak, day and night. Justnot me.

Also at Pike’s Peak is an RV camp-ground and a very nice short loop trailthat features dozens of Indian mounds,including a couple of unusual effigymounds in the shape of bears andbirds.

Page 13September 2002

right outside a shop that sells “FreshSmoked Carp.” Sounds like an oxymo-ron to me.

We spent the week in the usual Heath-Nagel manner, kayaking and boatingand hiking and sampling the localbrews, of which Lake Louie Lager is adefinite keeper. And most importantlywe spent it not flying. I was gettingserious sailplane withdrawal symp-toms, a classic case of GPS. But I had abackup plan!

Greg Smith had sent me informationabout the Platteville Mound, a milelong geological oddity planted in themiddle of Wisconsin cow country. Itwas right on our route home. So as theHeath-Nagel clan made its way backtoward Monroe, Wisconsin, the Nagelbranch of the clan diverted off intosuburban Platteville to check out themound. The Platteville Mound is nothard to find. You can see it from 15miles away on a clear day, a longwooded ridge running north andsouth, and standing a couple ofhundred feet above the rolling farm-land of southern Wisconsin. The southend is cleared of trees, and has cellphone towers on the top. A giant white“M” is emblazoned upon the clearedslope. You can’t miss it, as they say.

Greg told me that there is an accessroad up to the top, running betweenthe house and out buildings on a localfarm. I figured that the farmer mightnot be ready for The Beverly HillbilliesGo Kayaking, so we drove around tothe little park at the base of the giant Minstead. There is a loooong set ofwooden stairs to the top of the slope,and a marker explaining that this is theworld’s largest capital M, created outof white washed rocks in the 1930’s byengineering students at the Universityof Wisconsin. What the marker doesn’texplain (but is painfully evident) isthat the Wisconsin engineering stu-dents were holding the blueprintupside down when they laid out thegiant letter.

We hiked up the wooden steps,stopping to rest and gasp from time totime, and found there was a light westwind blowing. The slope faces west,and it was time to break out the U-2again. Rew heaved the plane for me,and it became immediately clear thatthe winds were way too light for theU-2, which (to paraphrase Monty

Python) did no soar so much as itplummeted. It dove and stalled andwobbled down the face of the giant M,glided across the road, over or underthe phone lines (not sure which) andacross the front lawn of the houseacross the street, where it disappearedunder the lilac bushes with a thump.

We hurried down the stairs again toapologize to the home owners. No onewas home. Rew called out to me: “HeyDad, the U-2 has done what it doesbest.” It had bounced, popped off bothwings, and wound up unharmedunder the bushes. No harm, no foul, noflying: a typical HSWT saga.

If you pass through Platteville, Wis-consin, and west or southwest wind isblowing, check out the M Mound. Alsotake a look at the local mining mu-seum, and of course the Lake LouieLager. Directions to the Giant MMound can be found on Greg Smith’sslope locator site, www.slopeflyer.comor you can look just east of Platteville,Wisconsin on www.topozone.com.

It was time to head home. We headeddown through Illinois, listening to a

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Specs. ASW-24 PILATUS B-4 LUNAK LF-107 DISCUS (1:3.5) DG 800 (1:4.5) NIMBUS 4-DWing Span: 64 in. 57 in. 66 in. 168 in. 137/165 in. 130 in.Length: 28.3 in. 29.5 in. 28 in. 74 in. 62.5 in. 46 in.Wt: 11 oz. $159.95 10.5 oz. $149.95 15 oz. $159.95 200 oz. $1395.95 123 oz. $999.95 54 oz. $599.95

ZIKA

GONE SOARIN’

great little jazz and blues stationowned by the Illinois State University,WGLT. We stopped to eat at a CrackerBarrel just off the interstate. It turnedout we were in the twin cities ofBloomington and Normal Illinois.Under close questioning the waitressadmitted that we were actually justinside Bloomington city limits, andthat Normal was two streets over.

And that, dear reader, is as close toNormal as anyone in my family hasever been.

Travel well, fly safely, and write if youget lift.

n

R/C Soaring DigestPage 14

BMFA F3J NewsBMFA F3J NewsBMFA F3J NewsBMFA F3J NewsBMFA F3J News

Uncle Sydney’s Gossip Column – 16

by SydneyLenssen, Englandsydney.lenssen@virgin.net

Dateline: 15 August 2002

FINNISH YEAR OF THE SPEAR

Finland’s World F3J Championshipin Lappeenranta was “the spearing

champs.” If you missed the 100landing and/or didn’t fly 9.50 pluseach round, then no fly-off for you.The margin between top qualifier JurajAdamek from Slovakia at 7,994.65 -nine flights, one dropped - and 12th

equal place of Canada’s Graeme Clarkand Germany’s Reinhard Vallant at7,962.33 is the equivalent of dropping22 seconds over eight rounds, less ifyou lose any landing points.

The fly-off was even tighter. NewWorld Champion Arend Borst beat1998’s WC Joe Wurts into second placeby 0.7 points out of 3,000 – four roundswith one dropped. That is as near asyou can get to 0.7 seconds in the 15minute fly-offs! And how he did it. Forinstance, Arend from Canada tied withAustralia’s Carl Strautins in the fourthslot, each with 14 minutes 56.2 secondsplus 100 spot landing. Zoom offhalfway up the launch line, or you’regone!

Despite such tiny margins, F3J WC2002 was exciting and unpredictablewith victims and heroes each round.What made it a spearing contest wasthe ground at Lappeenranta’s airport,hard bituminous gravel and rocklumps with little protective soil orgrass, presumably scrapings from eachyear’s frosted runway. Anything otherthan spearing the nose risked a ran-dom slide out of the metre circle.

During the Wild Man’s Trophy beforethe champs began, both Joe and Arendlanded on the actual spot itself, madeof ply, and as a result slid into the 95s.To prevent that, the Canadian team toacclaim replaced all spots with softermaterial which the nose could pierce.

But it’s a sad outcome of such tightwinning margins that today’s F3Jmodels must be built to take dunkedarrivals, some of them fast. Scaled upto full size equivalent, each and every

pilot would be killed outright and theglider severely damaged, if not writtenoff.

How to make the winning marginsbigger is the problem taxing F3J, andin particular FAI jury members SandyPimenoff, Tomas Bartovsky and NickNeve. Wider point differences areneeded because today’s timekeepersneed to time flights to two decimalplaces of a second to get a result. Thearithmetic and percentages are easyenough to calculate. The reality is thatwe are basing results on margins,which are less than any normaltimekeeper’s ability to start his stop-watch exactly as the glider leaves thetowline.

For many flyers, the essential attrac-tion of F3J is simplicity: launch,thermal away, then land with preci-sion, time and place. Easy! But withWorld and Euro champs, and increas-ingly at Eurotour events, the competi-tion becomes “launch and landing” -getting off the line quick, never mindthe height, and land with a prodmilliseconds before the beep.

Thermalling for the top flyers is takenas read, hardly surprising when AlexHoekstra reckons his Twisters can do10 minutes in still air with a goodlaunch. Joe Wurts and at least a dozenothers seem to find lift or enoughshifting air to maintain height what-ever the conditions. At Lappeenrantamore than 90% of flights flew out slots.

Some top pilots are happy with ever-tighter contests. Karl Hinsch reckonsthat summer Eurotour events havegone that way, and he enjoys competi-tion with no margin for error. He’s notalone amongst Europe’s top pilots, JanKohout and Michel Wagner think thesame.

Change discussions on and off the fieldcentered on shorter towlines, down tosay 100 or 75 metres. That is no an-swer, it just means developing everfaster launches, lighter, maybe smallermodels. It will not take a year to matchcurrent launch heights.

The Japanese suggested that thecontest director should set the slot timeat six, ten or fifteen minutes at the startof each round, according to the pre-vailing conditions. If the air makes foreasy thermalling, then set the shorter

time. If it’s grotty, force everyone toscratch for fifteen. That approach couldsort out the men from the boys. It putsan onus on the CD, and it’s interestingto speculate on its effect. But it’sunlikely to command wide enoughsupport to get CIAM to change rules.

Best solution to date, which wouldupgrade thermal skills – the missingingredient - is to force pilots to leaveany thermal lift they have found partway through the slot and find somemore. One method would be to set upsight lines as in F3B, 300 to 500 metresfrom either end of the launch corridor,with judges sighting along two planesat 90 degrees to the launch line. In thefirst half of the slot, pilots would berequired to cross one sight line, left orright, and in the second half of the slot,cross the other. The reward could besay 250 points for crossing both.

Such an additional task would requiremore helpers and perhaps a largerflying site. How to identify each gliderhas not been solved yet. But it wouldbring new spice. Any other ideas?

For F3J WC 2002, the stake (or non-stake) was forgotten. Admittedly atLappeenranta airport, it was easy toensure that the anchor pin was rocksolid, so much so that the change in thedirection of the flight line was a majoroperation. But it was done a couple oftimes, thanks to Czech pressure, forthey had had a horrible accident withcross wind launching.

The only rule spat was over reflights. Itis impossible for the contest director orhis deputy on the line to witness every“interference with flight,” so it is oftenleft to the timekeeper. One pilotclaimed his zoom was impeded whenone of his towers almost tripped over astake left in the ground. His spotterand team manager claimed a reflightimmediately, but that was denied bythe timekeeper, one of a band ofexcellent volunteers who did a greatjob most of the time. So the flyerrelaunched.

The contest director ruled out asubsequent claim for a reflight, be-cause the flyer had gone on. So theteam appealed to the jury, who thendeliberated for a long time beforeruling that a reflight should have beengiven. They had taken so long that thereflight came at the end of the next

Page 15September 2002

round. That yielded more appealsfrom other teams who have lost out insimilar events.

In its wisdom the jury produced amatrix of what constitutes grounds fora reflight. They should not have tried,for that produced even more confusionand highlighted conflicts in the currentrules.

My bet is that CIAM will eventuallynot allow reflights, full stop, duringlaunch or in the slot. If flyers choose tofly close and are impeded, then that isa risk they have chosen to take. Badluck to those who gamble and fail.That will discourage flocking in thesame tight patch of lift. It will meanmore launch risk if you zoom close to aless experienced pilot.

Juries should take heed: don’t try toclarify the rulebook during the event -a sure recipe for trouble. Be the highand mighty gods who rule withoutfear or favour!

+++

Let me not crow, but July’s gossipcolumn gave Arend Borst as hot tip towin F3J WC 2002. Behold, he did –only just. A popular winner, modest inthe nicest way, he is always ready toshare his experiences and tips. Every-one was pleased for Canada, hosts forthe 2004 world champs just outsideCalgary. The team performed wellabove everybody’s expectation insecond place. With two in the flyoff,Canada matched the might of theSwedes, German and Czech teams.Well done.

I am confident they will do equallywell in organising F3J WC 2004 as thebest of all champs so far, so startsaving for that transatlantic voyage.

My “long odds bet,” Denmark’s JesperJensen, footed the flyoff table afterplacing 7th in the preliminary rounds,a worthy performance, as indeed itwas for anyone to reach the finals.Finland’s neighbour Sweden did wellwith Pasi Vaisanen in 3rd place andSoren Svantesson in 12th place.

Happiest two guys on the airfield werethe Lammleins, Tobias the new juniorworld champ and his father Stephan,German junior team manager. Tobyhas been on the winners’ rostrum threetimes before, and desperately wanted

the No.1 spot.

His mother, holidaying about 100 kmaway, stayed away from Lappeenrantaduring the week, frightened that shewould increase the tension. But shewas there to share Saturday’s last twoflyoff rounds. He could not be beatenafter the third round of the flyoffs,when he flew out in the first and onlyslot that morning in mostly dead stillair. Even so, with spotter Philip Kolb,he found enough buoyancy to keep hisSharon up for the full 15 minutes, atrue champ winning performance.

Hand it to the German Junior team,winners again, for the third time.Which country can wrest that titleaway? With more than 30 juniorsflying regularly in the German League,some of them filling the top slots in thesenior league, F3J has an assuredfuture there.

One bet that I did lose was withAustralian correspondent Ian Roachwho objected to my low expectationsfor Australia. I bet him subsequentlythat UK’s Simon Jackson would beathis favourite, Carl Strautins, and I nowowe him. Mind you, Carl had bothmum and dad loyally supportingprowess in Lappeenranta, and theyenjoyed themselves.

+++

The UK team performance? My viewof events: eight of us flew in the WildMan’s Trophy on the Saturday, whichgave lessons on where to go – behindthe hanger dodging the pines – if youmissed the main lift. The site hadthermals galore most of the week, withonly the odd early and late slot provid-ing challenges. But the hanger provedvalid most of the week.

British results look modest on paperand again disappointing, to no onemore than the three flyers themselvesand their helpers. They hide especiallythe bitter personal disappointmentsand disillusion for Mike Raybone andSimon Jackson plus Phil.

Of the three, Neil Jones did best and tohis delight he crept into the top 30! Inall fairness, he did not have a slotwhere he couldn’t catch the bunchwith the lift, not that that is alwayseasy! If he could have nailed a fewmore 100s in landing he would have

ranked still higher.

Neil kept his cool and was leastunnerved. One evening waiting for alate slot around 8:00 pm, the air turnedchilly and Neil jogged off to keephimself and more importantly hisfingers warm. As newcomer to interna-tional events, Neil thrived best.

Mike had the very worst of luck inpractice before the champs, piling intothe taxiway and destroying his Star-light on launch, still on the line. I say“his” but it wasn’t. It was Dave East’sStarlight, Mike’s reserve, which madeit even more of a loss. Then to cap itall, his first contest round was poorwith less than 600, sure to be thethrowaway.

All very demoralising, and Mike didwell to recover reasonable scores inmost - not all - of the remainingrounds. So by Monday night, in mymind we had one out, but two still inwith a chance.

Simon started well with a 987 and hisfirst Finnish 1000, then a 990 and –tragedy in the 4th slot - a bummer. SoTuesday, again to my mind, gave ustwo down, one to go.

Let’s put this in context: my presump-tion was that if the UK team all got 9minutes 50 plus, and 100 or perhaps 95landing points, then they should reachthe flyoff. On that basis, Neil was stillin. But by Wednesday, feeling morerelaxed and with time to spare, studyof the scores showed that I was kid-ding myself. Some slots had flyersscoring 9 minutes 50 plus spot landingand coming sixth.

My “one down and two to go” wasrubbish. Reality was that all three UKflyers were out of the flyoff by the endof the first day, barring catastrophes bylots of others. Plenty of well knownfavourites – Philip Kolb, AlexHoekstra, Jan Kohout amongst them –made the odd error landing 10 secondsearly or making 65 points on landing,and they were out.

In my opinion, this year’s UK teamperformed as well if not better thanany over the past four years, and wehad the luxury of six keen and fittowmen. Anticipating the start becamesecond nature with the standardrecorded countdown, soon to be

R/C Soaring DigestPage 16

adopted here. On the buzzer the helpersimply launches. Landings were notup to 95 or 100.

If pressed to point a weakness, it’s areluctance to hack it in light shiftinglift which cost dear in a few slots, andthat’s not surprising for such weatherpatterns in England are rare. Top pilotsjust circle gently and slowly at timeswhen all is almost still, waiting pa-tiently, not going up or down, until awisp of lift gradually builds. Few UKflyers see it that way. They want andlook for stronger lift. Leave the pack,and chances are they are doomed anddown. British F3J standards have goneup. Snag is that standards in severalother countries have gone up more.

The UK team held together in spirit.We had a great time, spent too muchmoney – not all at local nightclub Dorisor McDonald’s - and shared in thedelights of a closely contested champi-onship set in a very different holidaytown.

+++

Memories of F3J WC 2002:here are a few.

First, best thanks to CD Erkki Arimaand his team. He cut most of the

crap and got on with it, not alwayseasy with lots of languages and anoperational airport. His scoring andcomputer team was superb.

Other organisational matters wentadrift. Where was the WCProgramme? The final banquet was adisaster, even prize-winning teams didnot get in. At the prize-giving cer-emony, wrong anthems were played.Many competitors felt they wereovercharged for what they got.

Thanks to all the Turks who helpedUK team again and again.

Smallest junior competitor was JouniLauren from Finland, and he wasunusual in that his spotter was also ajunior. (Maybe CIAM should think ofmaking that a rule, by the way!) Theyhad a delightful way of workingtogether, so simple and I have neverseen it before. If the spotter advisedmoving left, he tapped the left shoul-der; similarly for right. If he wantedyou to come nearer, the tapped themiddle of the back, forward he tappedthe back of the head. The system

seemed to work well and was a delightto watch.

The Japanese team came with hlg’sagain, as in Corfu, still the simplerudder/elevator, light balsa/foamwing, carbon kevlar fuselage, but thistime SALing. What heights they couldreach, followed either by super tightthermalling or a display of amazingstunts before coming back to hand. IfShuhei Okamoto who manufacturesthem for Craft Room in Japan wouldsell these in UK, he would have awinner. Even Joe Wurts was im-pressed.

Alex Wunschheim, the German teammanager who is also Eurotour’s F3Kcoordinator, had his hlg too, alsoimpressive but far higher tech. TheJapanese took out his complete tail in acollision when the two launchedtogether too closely, Philip Kolbhaving warned that it could happenseconds before.

I enjoyed Larry Jolly’s electricornithopter, which looked for all theworld like a real bird of prey. It flewfor 7/8 minutes, could climb to goodheights, hover and land in the handjust like a falcon. Hope to get moredetails of that soon.

Joe Wurts is normally a most modestguy, and another delightful chatterbox.From time to time he shows off.During the main contest, he limitedthat to spins or distance laps on thelanding approach when space allowed.

But during the Wild Man’s trophy, hethermalled most of one slot inverted.In another round, he put his transmit-ter down on the ground and lay downbehind his spotter, not touching thesticks for all of two minutes. When the

best flyers’ models seem to fly them-selves for long periods, a minute ormore is not unusual. Then the pilotspends his time looking round theskies and reading the air. It takes meall my time to make sure I don’t losesight of the thing.

One more tale, not from Finland butInterglide, the weekend before. Mygroup was short and we had the goodfortune to be joined by AustraliansCarl Strautins and team managerDaniel Haskell. Both Carl and ex-UKjunior Andrew Taylor made the flyoff.At the end of the two days, bothAussies taught me ways of saying“cheers”.

The Aussies found it remarkable thatso many people in Kent were drinkingbeers between slots. Alcohol andmodel flying are not mixed down-under. Now that could explain whywe don’t take the top places thesedays. I won’t be rooting for an earlyAustralian F3J WC!

End of gossip. n

ZIKA

model needed acorrection, he usedhis toe. What madeit memorable wasthat in the secondflyoff round, he losthis landing bonusand top prize whenthe model slid andhit his foot.

But there’s apurpose to this tale.My lesson from aweek of fantasticflying is that the

Page 17September 2002

Jerry Slates556 Funston Drive

Santa Rosa, CA 95407RCSDigest@aol.com

Jer'sWorkbench

ZIKA

“Sailplanes 1945-1965”Written by Martin Simons

A Book Review

Most of you are probably wellaware of Martin Simons’ works,

as he’s been involved in gliding, bothfull size and R/C for more than 50years. Over the years he has pilotedabout 150 different types of sailplanesand earned a well deserved Gold CBadge and two Diamonds. He is a firstclass, accomplished R/C sailplanedesigner, builder and flier.

Martin has authored many books overthe years including Sailplanes 1920-1945, Sailplanes by Schweizer, andModel Aircraft Aerodynamics, three ofmy favorites. And, in his spare time,he’s written many magazine articlesfor all of us, many of which appearedin past years as a series in RCSD.

Martin’s newest book, recently re-leased, is “Sailplanes 1945-1965.” And,for me, it’s not a book best left layingon a coffee table, even though it’sbeautifully bound, numbering 272pages. Nope, this is a book destined tobe read cover to cover, and more thanonce. The detailing on the 3-viewdrawings is absolutely amazing, and isaccompanied with B&W or full-colorphotography and accurate historicaltidbits and facts.

Before I provide a bit more detail onthe book, itself, I guess I shouldexplain insight gained over the yearswhere Martin’s writings are concerned.I feel I need to convey exactly whyMartin’s 3-view drawings are amazingand what’s so important about havingaccurate tidbits and facts.

Martin carefully researched, andvalidated the accuracy on each andevery plane in this book. He traveledto many countries searching for plansand any information that could befound buried in archives, correspond-ing with anyone who could assist or

provide in the validation of sailplanesdesigned and built between the years1945-1965.

No, we were not there while he waswriting his book, but we’ve seen himwork creating presentations, drawing3-views from scratch using a profes-sional graphics design program,following up on leads or modificationsfor two books, editing, and the like.Boy, is he a stickler for accuracy. (Anystudent fortunate enough to attend hisclasses at Adelaide, in Australia, mustsurely have been suitably impressed!)

You may be wondering why I felt itimportant to tell you a bit aboutMartin. It’s simple. This is supposed tobe a book review, but how does one doa review on something where there’snothing to compare and all the historyand findings took painstaking researchobtained over many years fromsources, some of which can no longerbe found?

Simply said, I’m pleased to have theopportunity to read Martin’s newrelease first hand and personally thankhim through the pages of RCSD for allhe’s done for not only us RCSDreaders, but for the history he’smanaged to preserve for all soaringenthusiasts!

And back to the book...

I traveled from Argentina toYugoslawien, the first section beingabout “The Old Tradition,” in alpha-betical order. I was captivated bystories covering sailplanes like the everpopular Grunau Baby-4 and SchweizerSGs 2-22. Unusual sailplanes rarelyheard of include the Scnneider ES 526Longwing Kookaburra and the PIK 5Cumulus.

The next section, Part 2, focused onlaminar flow, smooth skin. In thissection, I read that in 1948, no Ameri-can designer had produced a sailplanewith a glide ratio better than 30:1.However, Dick Johnson and HarlandRoss wanted something better. So,using their RJ-5, they spent thousandsof hours re-working the RJ-5 and, by1952, achieved a glide ratio of 40:1.

Part 3 takes us to the subject of glassships, new materials and new prob-lems. Since glass-reinforced (GRP)structures are relatively new, muchhad to be learned. These new materialswere strong in tension and compres-sion, but were highly elastic; in time,these problems were worked out.Some of the first GRP sailplanesinclude the Hirth Hi-25 Kria,Braunschweig SB-6, and Glasflugel BS-1.

Well, I found some great informationfor building my next scale model and,if any of you are looking for this kindof information, Sailplanes 1945-1965 isavailable in the U.S.A. from:

Raul BlackstenP.O. Box 307

Maywood, CA 90270raulb@earthlink.net

Additional ordering information canbe found on page 18 of the May 2002issue of RCSD. The cost is $64.95 plus$4 p&h, U.S.A.

For those of you outside the U.S.A., thebook is available in German andEnglish versions from Equip Publish-ers in Königswinter, Germany; or,Aviation Bookshop in London, VGCSales Department, Midland CountyPublications.

n

R/C Soaring DigestPage 18

By Greg Smith of slopeflyer.comgreg@slopeflyer.com

http://www.slopeflyer.com

“The Sloper’s Resource”

Prodij 60-inch Racer fromAeromod

Every sloper needs the proper toolsto take advantage of the slope

experience and while almost anysailplane will fly at the slope, purposebuilt planes make the experience muchbetter. Having a diverse arsenal atyour disposal helps even more asspecific planes are better suited tocertain conditions than others. I plan toreview slope planes from time to timeand there is no better time than thepresent to get to it. So, without furtherado, I bring you the Prodij 60-inchslope racer from Aeromod in France.

The Prodij is a sailplane intended forhigh performance slope flight, racingin the 60” class and for use with thecatapults or bungee launch systems. Itssmall size makes it very handy withoutconceding too much performance. It ismanufactured in France by Aeromodand is available in the US fromF3x.com.

The wing is very strong and is madefrom carbon and glass. The top surfaceis formed in a mold and the bottom isbagged. It is not quite as pretty as afully molded wing, but it is much moredurable. I’ve whacked several saplingsat one local slope with a postage stampfor an LZ and the Prodij bounces backfor more. The ailerons go all the way tothe tip and are 30 % of the chordallowing the pilot to significantly alterthe airfoil through the use of theailerons as flaps. The wing sits on topof a small pylon. This lets the aileronsmeet in the middle with no interfer-ence from the fuse and is importantbecause all the servos are inside thefuse. This setup gives the Prodij a veryclean design and allows for effectiveuse of the wing over a wide variety ofconditions.

The fuse is a lighter lay-up than someslope ships I have but it is reasonablydurable, even more so after a bit ofcrash damage repair. (Around here wefly at some spots with questionablelanding spots or we don’t fly!) The slipon nose cone also adds some strengthup front. The fuse has fairly prominent

seam. Some guys may want to takesome time to smooth the fuse andrepaint it. It does not bother me so Idid not waste time on it.

The tail is a sandwich of balsa, fiber-glass and balsa with the glass acting asthe hinge. Simple, but strong andeffective.

The servos mount to a ply palette andthe palette is in turn screwed to theside of the fuse. I mounted mine on theleft side of the fuse and there is enoughroom on the right to Shoo-Goo a 12inch long piece of 1/2-inch diameterPVC electrical conduit for use as aballast tube. I can get about 12 oz. witha steel bar and more with lead, al-though I have not cast the lead pieceyet. On this plane 12 oz. is pretty good.The thing is already fast because of thethin airfoil and the clean wing so theweight helps it really cook.

A building note

The recommended silicone hinges forthe ailerons are cool, but watch out fora reaction between the silicone you useand the tape that holds the ailerons inplace while the silicone is drying. Mycombo of GE Silicone II and 3M bluepainters masking tape was not the hotsetup so I had to redo it. There wassome reaction between the adhesive onthe tape and the silicone. Lay a beadon the proposed masking tape andwait a day to see if the silicone curesproperly. (This tip applies to any planeusing silicone hinges).

I used this plane for the UnlimitedClass at the Midwest Slope Challengein 2001 and was very impressed withhow fast it was in the light conditions.Several people commented on howquickly it accelerated when the nosewas pushed down. In fact the accelera-tion helped me win one of the heats aswe both dove for the finish line.

The durability of the plane was alsotested at the MWSC in a race where thewind had come up allowing somegood height to be gained before thestart and as my competition and I dovefor the starting line, holding until thelast possible second to pull through,about 2 feet off the deck, he bouncedoff the top of my Prodij slamming meinto the ground. I am not sure how fast

we were going, but it was fast for sure.Several people thought the plane musthave been destroyed. As it turns outjust a small hole was punched in thenose cone and the tail boom cracked;easy enough repair and it is strongernow.

I had the Prodij DSing in South Dakotaon a recent Slopin’ Safari and it kicksbutt. I noticed in previous flights that ithandles like a larger plane and the sameholds true in the DS circuit, especiallywith the ballast. It covers lots of groundand really retains energy well. I wasgetting 400-500 foot punchouts afterbuilding up the speed!

The Prodij flies a bit differently thanmost other planes. You can fly it like aconventional 60-inch racer and it willalready be as quick or quicker thanmost. But if you really want to extractthe most performance make sure youset up your radio to use the left(throttle) stick to work the trailing edgeas flaps. To get the plane to fly in lighterlift and really haul in heavier condi-tions, you have to be able to add camberor reflex proportionally. I have the flapset at neutral when the left stick is in themiddle and am constantly using the leftstick to change the wing to maximizewhat I am doing. This is the way thedesigner intended the plane to be flownand a significant performance gain canbe realized by taking the time to learnthe slightly unorthodox style.

The best part about the plane, besideshow well it flies and the durability, hasto be the price. $215 last time I checked.If you are interested in one, call or e-mail Tom at F3x.com.

I’ve mentioned this before but theunderwhelming response prompted meto mention it again, I am looking forslope stories from your experiences,from years past or days past. We wantto know about your homebrew slopeplanes, construction techniques orthoughts on your new foamie. Espe-cially if you are planning on producinga new slope plane or product for sale!We all want to know about it. RCSD is asuper resource and in all likelihood theonly pure R/C soaring magazine left inexistence. Contributing an article fromtime to time will only strengthen analready great magazine. If you areinterested send a note togreg@slopeflyer.com.

Until next time... n

Page 19September 2002

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

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

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

ESL Web Site: http://www.e-s-l.orgESL President (99-00): Tom Kiesling (814) 255-7418 or kiesling@ctc.com

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

League of Silent Flightc/o AMA

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

http://www.silentflight.org

SailplaneHomebuilders

Association (SHA)

A Division of the SoaringSociety of America

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

Dan Armstrong, Sec./Treas.21100 Angel Street

Tehachapi, CA 93561 U.S.A.

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

For Sale - Business

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

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

Reference Material

BBS/Internet

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

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

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

web site: www.soaringissa.org

InternationalScale SoaringAssociat ion

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