R/C Soaring Digest - Dec 2003

Page 1December 2003

December, 2003Vol. 20, No. 12

U.S.A. $3.50

R/C Soaring DigestPage 2

TABLE OF CONTENTS

3 "Soaring Site" ............................................ Judy SlatesEditorial ................................New Web Site for Houston Hawks.................................................................... On the Home Front............................................................................Gift Idea Issue

4 "On The Wing..." ........................... Bill & Bunny KuhlmanFlying Wing Design & Analysis .............. Jochen Haas' Taborca

7 Review ......................................... Bill & Bunny Kuhlman.................... The Golden Age of Model Aviation by Alvin Sugar

8 Christmas & Gift Giving Ideas................. Dave Register................................................................ Bill & Bunny Kuhlman.................................................................................Greg Smith........................................................................... Dave Garwood

14 Sailplane History .............................. Anker Berg-Sonne.................................................................. History of the Mantis

20 Technical Analysis & Design ....................... Mark Drela.......................................... Elastic Modulus of Common Foams

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

Page 3December 2003

TheSoaring

Site

Happy Flying!Judy Slates

TABORCA

Launching Taborca at theTeck hills in southwest

Germany.

Jochen Haas’ Taborca is thesubject of “On the ‘Wing...” thismonth, written by Bill & BunnyKuhlman.

New Web Site for Houston Hawks

We received a message from GarySeawright, webmaster for the

Houston Hawks in Texas. They have anew domain name and web site:

http://www.houstonhawks.org

The RCSD web pages were updated byour web masters, B2 but, alwayscurious, we took a quick trip to theweb site to see what the HoustonHawks had to say.

There is a 30-Day Introductory PilotProgram, which “allows any person toexperience the excitement and chal-lenge of radio-control soaring, whetherthey have a sailplane or not. Onceregistered, a person has 30 consecutivedays of FREE one-on-one flightinstruction with a certified AMAinstructor pilot using the HoustonHawks Hangar 9 Aspire. To start yourflight instruction, contact one of theinstructor pilots listed below.”

List of Certified AMA Instructor PilotsMike Kovacs

Don ClevelandJack Womack

The Hangar 9 Aspire has a 79-inchwingspan with a modified Selig 7037airfoil. The Aspire uses 2 channels: onefor rudder (yaw) control and anotherfor elevator (pitch) control. The imageis available for viewing from their website.

On the Home Front

This past month, the RCSD ResourceListing for the U.S.A. was updated toreflect the latest contact information. Itis available for downloading from themain RCSD web page. Should any ofyou note additional changes thatshould be made, please don’t hesitateto let us know!

Effective this past month, RCSD nolonger accepts commercial advertising.Personal advertising, club information,

and special interest groups, as always,are exempt.

Gift Idea Issue

As most of you are aware, the writersand columnists volunteer their timeand energy providing information onthe subject of their choice, and theyonly share information on sailplanesand related accessories. That meansthat we write what we want to writeabout and that we think will be ofinterest to most of you.

This month is no exception, as thisissue contains a special article, coordi-nated and edited by Dave Register, onthe subject of Christmas or SpecialOccasion gift giving ideas. Our thanksto all of the folks that provided infor-mation for the article and to Dave forhis coordinating efforts. (Being an editoris not always easy, and we appreciate it,Dave!)

And, in the midst of all this, in addi-tion to writing his own column, Davehas some personal things happeningon his own home front. For those ofyou that know Dave, and for those ofyou that enjoy reading his column, aget well message would be wellreceived. He’s at <[email protected]>or, at least, he should be there ifthey’ve let him out of the hospital andgiven him his laptap computer back!Get well, Dave!


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

Layout of the components of theTaborca electric version.Jochen Haas’ Taborca

Our “On the ’Wing...” column inthe August 2001 issue of RC

Soaring Digest was devoted to JochenHaas. Jochen’s spreadsheet, formu-lated to assist in the design of sweptwing tailless gliders, remains availablein both Excel and AppleWorks for-mats. As that column was beingwritten, Jochen was working towardgetting a kit of the Taborca 3 manufac-tured by a major firm. This month’scolumn is devoted to examiningTaborca in detail and providing anAmerican source for the LET Modelkit!

Taborca is an exceptionally beautifulswept wing sailplane designed forslope soaring and F3J flying. The wingutilizes the MH 45 airfoil, is sweptback 24 degrees, and uses what hascome to be known as a “six flap”

control system. There is no rudder. Thewinglets increase the effective aspectratio from 12.8 to 17.

The wing sweep of 24 degrees and thesize and location of the various controlsurfaces are coordinated so the liftdistribution can be tailored for sepa-rate flight regimes. Control surfacedeflections are set up so the yaw, pitchand roll functions do not interact.

The included illustration shows thecontrol surface deflections for variousflight regimes.

For roll to the left, the elevon of the leftwing goes up and the combi-flap of theleft wing goes up to a lesser extent. Onthe right wing, the combi-flap goesdown and the elevon goes down to alesser extent. The idea is to eliminateany pitch change by having the control

surface deflections balance each otherout in the vertical dimension while atthe same time eliminating adverseyaw.

For left yaw, the elevons and combi-flaps operate in opposing directions sothat there is no pitch input, only anincrease in drag on the left wing.

The flaps are used to assist the elevonsin elevator mode.

The elevons and combi-flaps can bedeflected slightly upward to increasethe speed when traveling betweenthermals. A small amount of down-ward flap deflection is used to im-prove distance performance andthermal climb.

The flaps and elevons deflect tomaintain pitch stability when the

combi-flaps are deflected downwardto act as air brakes. This is equivalentto “crow” on a conventional tailedaircraft, and Taborca will slow downto a crawl and land very easily.

During all flight phases the flightcharacteristics are very docile. Theperformance envelope and speedrange of Taborca is very close toconventional F3J models. The mini-mum speed is astonishingly low, andthe climb performance whenthermalling is even better than conven-tional models.

Full utilization of the six-flap controlsystem mandates a sophisticatedtransmitter with a number of mixingfunctions. Recommended transmittersinclude the JR 10X and 8103.

Page 5December 2003


Access hatch open. The spar system doesnot produce any obstruction and all servos

are mounted in the wings.

The relative size of Taborcais seen in this photo.

The huge flaps are fully deflected inthis photo. The sub fin drives the

wing to a negative angle as soon asthe aircraft touches the ground,

eliminating any bouncing.

Taborca is a RTF sailplane, ready forinstallation of servos and other radiogear. It is obeche over foam withcarbon fiber spars and Oracover whichis professionally applied. The uppersurface is white, the bottom surface isof contrasting color. All controlsurfaces are pre-hinged and servocables are installed. The transitionsand wing-fuselage junction are im-proved over what is shown in theincluded photos, and the wingletshave been strengthened.

An alternative fuselage for an electricversion is also going to be available.The original setup included a TorcmanTM 280-20-16 with a Master 40-3P 6-16NC opto Jeti speed control, 10 cells,and a 12.5x6 folding prop in a tractorconfiguration. Dieter Mahlein ofShredAir has suggested an improvedmotor drive system using high qualityLehner equipment: Lehner LMT Basic5300 motor and Reisenauer Microgear5:1 with BK/LMT Warrior 7018controller, 70A continuous and eightCP-3300 NiMH cells, zapped, in twosticks of four cells, soldered end-to-end. This system would drive an RFM14x10 carbon propeller with a clamp-on Norbert Meyer Lightspinner(diameter to be determined). TheLehner system offers good perfor-mance at a relatively low cost of under$400 without the battery.

There will be a molded version ofTaborca in the future. There is noweight or structural advantage to amolded wing — the only real differ-ence is in the finish. The foam andwood wing is of course more easilyrepaired, an important consideration.

John Derstine/Endless MountainModels is the U.S. importer for thisdesign via LET Model. The sailplaneconfiguration will be priced betweenUS$750 and US$900; no price range forthe electric version as yet. You canobtain information from the EndlessMountain Models web site news page<http://www.scalesoaring.net/EMM/emm news2.htm>. If you havean interest in purchasing a Taborca kit,contact John through<[email protected]>, a speciale-mail address.

_____

Derstine, John/Endless MountainModels. RD#3 Box 336, Gillett PA16925. Phone: 570-596-2392, weekdayevenings 7:00 to 10:30 PM EasternTime. Weekends any time.<[email protected]> <http://www.scalesoaring.net/>

Kuhlman, Bill and Bunny. The flyingwings of Jochen Haas. RC SoaringDigest, August 2001. Available at<http://www.glide.dyndns.org/on-the-wing3/156-Jochen-Haas/156-Jochen-Haas.pdf>, software at <http://www.glide.dyndns.org/on-the-

wing3/156-Jochen-Haas/Haas-software-Windows/> and <http://www.glide.dyndns.org/on-the-wing3/156-Jochen-Haas/Haas-software-Macintosh/>.

—. Six-flap control systems. RCSoaring Digest, July 1995. Available inOn the ’Wing... the book, Volume 2<http://www.glide.dyndns.org/on-the-wing2/OTW-Vol-2.pdf>, 9.9 MB.

Mahlein, Dieter/ShredAir. P.O. Box10093 Eugene, OR 97440. 541-954-6842.<[email protected]> <http://www.shredair.com>

• • •

Page 7December 2003

Al Sugar’s Shuttle LastChance, his “ideal”

sailplane for the low launchenvironment.

The Golden Age ofModel Aviation

by Alvin Sugar

A Review by Bill & Bunny Kuhlman

Although Bunny and I havedabbled with foam core vacuum

bagged wings, our most enjoyable taskis the construction of a flying surfaceusing open bay construction. Theresulting structure, with transparentcovering and the sunset illuminatedsky gleaming through, is always asource of awe for us. And we findourselves much more satisfied beingable to maintain altitude in an eveningbubble of light lift than being able tospeck out in turbulent lift at midday.Additionally, after being in a thermalfor several minutes, we find ourselvesgetting bored. We find it very hard toresist the intense desire to come backupwind, land, and immediately launchagain in search of a new thermal toride. All of these tendencies contributeto our interest in Mr. Sugar’s ideas asto the real definition of soaring perfor-mance.

The Golden Age of full size aircraftwas the period between roughly 1925and 1935. In that decade, man madeastoundingly huge advancements inaviation with tools no more sophisti-cated than the slide rule. The NACA

four digit airfoil series was developed,numerous aerodynamic devices wereinvented, engine performance im-proved dramatically, and controlsystems became more sophisticated.Aircraft performance made a giganticleap as a result of those innovations.

In the mind of Alvin Sugar, the GoldenAge of model aviation, specificallywithin the realm of RC soaring, wasthe period from about 1965 to 1975.During that ten year stretch, propor-tional radio control became morereliable and light enough for use in aglider, and F3B came into existence.While Ed Izzo had demonstrated foamcore wing construction in 1964, openframework wings were still the normat the end of that period. The big RCsoaring leap came in the form ofadvanced flying skills rather thanaerodynamic improvements or con-struction methodologies, and theability to go out and “hunt” forthermals became a distinct advantage.

In the intervening years, the basic RCsailplane has evolved into a “hightech” machine capable of travelinggreat distances at high speed and greatheights — higher-faster-farther. In themind of Mr. Sugar, however, soaringperformance has not really improvedmuch. Rather, RC sailplanes have been

designed and constructed to achieveextremely high launch heights, to theboundary between model and full sizesoaring and beyond.

Mr. Sugar has written this book tobetter explain his philosophy as towhat an RC soaring machine shouldbe, based on his statistical methodol-ogy for evaluating performancethrough the “low launch.” The GoldenAge explores how the aerodynamicprinciples of lift and drag, stability andcontrol can be coordinated with mass,inertia, and other physical propertiesto produce the best soaring tool for thedesigner/flyer and his local environ-ment. The articles within The GoldenAge therefore cover a very largenumber of topics. As a result, this bookis a 99 page collection of two dozenarticles which are devoted to aerody-namics and structures, physics andflying skills, flight altitude andweather.

Al starts out with an explanation ofhow airplanes fly. (The Golden Age isone of the few resources which de-

(Continued on page 13)


Christmas & Gift Giving IdeasFrom the RCSD Team

Coordinated by Dave Register

At last, the 2003 holiday season hasarrived! With what this old

world’s been through since last year,it’s really good to look forward to alittle peace and family time.

Amidst all the ups and downs andturmoil in the world, there are at leasta couple of constants that we can counton:

- R/C hobby folks are some of thebest people you’ll ever know, and

- Building and flying R/C sailplanesof any type seems like it’s toomuch fun to be legal.

But legal it is! So to help you in yourquest to drop hints around the house,your RCSD columnists have again puttogether a list of hobby items thatmight be worth considering by yoursignificant other.

I would NOT suggest giving any ofthese as presents to your spouse/friend and then borrowing them back.Possible exception is Paula Garwoodwho might really want to have thatnew Moto drill or set of clamps. Forthe rest of us, that’s a ploy that usuallybackfires so don’t go there!

We’ve again tried to provide ideas thatgo from neat shop items to majorprojects and a bunch of things inbetween. Hopefully something in herefits your needs and your familybudget. Enjoy and Happy Holidaysfrom all the gang at RCSD.

FROM BILL ANDBUNNY KUHLMAN

http://www.B2Streamlines.com

Some time ago we received aGarretWade catalog. The catalogcontains some of the most beautifultools we’ve ever seen.

The selection of planes includes Lie-Nielson and Stanley, plus some no-name items made in England. Pricesstart at under $50 and go up to severalhundred dollars.

Any order from the catalog earns you adiscount on some specific item(s)

enumerated in the front of the catalog.We chose a set of five German madeclamps. They are exceptional and costless than $20.

Other items ofinterest to modelers:

Bankers‘ scissors - 7" from pivot to tipof blades, 3/$14.95. Great for cuttingMonokote and other covering materi-als.

Digital ”deep reach” calipers - 4" reach,$87.50 on sale for $79.95. You neverknow when the deep reach mightcome in handy.

24” vernier calipers - reads in 1/128"increments (0.05mm) with 2 3/4" jaws.Made in England. $24.95. The 24"length is a real benefit, and the price isright.

”Fast mount” shelves and tracks -tracks up to 6', brackets up to 22". Verysturdy. Sold by individual pieces, $3.50- $9.60. Utilitarian adjustable shelveswhich can take a lot of weight.

Diamond burrs - 1/8" shafts forDremel, etc. Cones, balls, points. 30pieces in wooden box, $13.95; 50 piecessupplement set is $19.95; both sets for$26.50. Great for cutting out odd-shaped plywood bulkheads, shapingsmall parts, etc.

Covered metal storage tins - Threesizes from 1 3/16" x 3/4" deep to 2" x7/8" deep. The two smaller sizes comein aluminum boxes, the large sizecomes in a paper box. 12 small $8.95,12 large $9.95, 20 micro $10.49. If youever wondered how to store replace-ment servo gears, small screws, orother odd items, this is it! Clear tops letyou see what’s inside.

Mini pliers - rubberized grips, serratedtips, interior gripping surfaces, 2 1/2"pivot. One is straight, the other curved.Both for $18.95. These are beautifuland comfortable, and the color setsthem apart from others.

Precision steel ruler set - 6", 12", and18" long. Hardened stainless steel. One

side is etched in 0.5mm and 1.0mm,the other in 1/64" and 1/20" incre-ments. $19.95. These come in indi-vidual plastic sleeves and are quiterigid. Have worked extremely wellwhen measuring and marking balsaand plywood parts.

Razor scraper - Beautiful brass oversteel with a comfortable roundedshape and rubber bound edges. Threepositions, takes standard single edgeblades. $4.50 each or 5/$18.30. Holdthe blade at 90 degrees for fine scrap-ing, or at shallow angle to get epoxyand CA off glass building surfaces.(Can also be used at a shallow angle toscrape burned spill-overs from glass-ceramic stove tops.)

Colorcoded miniature screwdrivers -four slot, 2 Phillips. Four inches long inplastic case. $10.95, 2/$18.60. Not thesets usually seen at Radio Shack andhardware stores.

Square set - Fixed engineer’s squares 2"and 6", 4" adjustable square withregular and 45 degree bevel blade, 4"flat rule (inches and mm). Made inIndia to tight British standards andpacked in wooden box, $49.95. Usefulfor setting up molds, built-up fuse-lages, wing ribs, etc.

GarrettWade161 Avenue of the AmericasYork,

NY 100131-800-221-2942

http://www.garrettwade.com

Our balsa, plywood, and music wiresupplier is:

Balsa & Hobby Supply12020 Centralia Suite G

Hawaiian Gardens CA 90716

Orders only: (800) 488-9525 7:00AM to7:00PM Mon - Sat PST

Information: (562) 865-3220 7:00AM to2:30PM Mon - Fri PST

FAX: (562) 860-0327http://www.superiorbalsa.com/e-mail: [email protected]

Superior also handles tools, dowels,epoxy, CA, bass wood, and carbonfiber, plus tools and other items. Wecan’t praise them highly enough.

Page 9December 2003

Excellent balsa and exceptional service.

We also found a shop vac which worksextremely well, is small (13L x 11W x15H with built-in handle) and easy tocarry around, plus is low in cost. It’sthe Stinger WD2000 by EmersonElectric. We picked up ours at HomeDepot. It’s got a two gallon capacityand is capable of wet or dry pick-up.The hose is four feet long and 1 1/4inch diameter, and it comes with a 1" x2" tubular attachments. Lots of other 11/4" attachments are available (crevicetool $6, wands $5, etc.) and these aresmall enough to get into those tightplaces that are inaccessible to theconventional shop vac attachments. Ithas vacuum and blower connectorsand a replaceable filter (3/$4). Nowheels, but the bottom of the canisteris shaped to slide easily across carpetor concrete floors. Oh yeah, it’s only$27!

For fun slope soaringor slope combat...

Michael Richter has updated theWeasel (36" span) and miniWeasel (24"span) kits, $50 and $35 respectively,plus shipping. Both Weasels have beengetting excellent reviews world wide.

http://www.dream-flight.com/testimonials.html

The Weasel web site URL has changedto:

http://www.dream-flight.com

The old URL which was published inthe February 2003 RCSD will automati-cally transfer you to the new site.Photos, movies, and the RCSD review(PDF) are all on the web site.

Michael Richter1250 Northridge Rd.

Santa Barbara, CA 93105phone/fax: 805 687 4435(Calls between 9AM and

5PM PST only)http://www.dream-flight.com

e-mail: [email protected]

Editors note - Also note that a greatpresent for those who enjoy “On the‘Wing...” is a compendium of manyyears of B2 columns that’s available onthe B2 web site. CD or download. Awonderful resource for understandingtail less flight.

FROM GREG SMITHTHE SLOPERS RESOURCEhttp://www.slopeflyer.com

Don’t forget the slopers!

The Weasel from Richter R/C is a greatlittle package and is cheap too! It’sbeen in RCSD a couple of times but itis still a super recommendation, asnoted above.

http://www.dream-flight.com/

The new 60-inch foamy warbirds havestepped up the performance of foamand are durable to boot. Look for themsoon at:

http://www.leadingedgegliders.com

The McLean Extreme is hands downone of the best slope planes in theworld if you have the cash and canwait for one to get built:

http://www.martialartsacademy.org/extreme.htm

Finally, the Airtech Pixel is a pitcheronplane that is a blast to fly and packsreally small. Caveat, I am the USimporter but it is still a great plane!

http://www.slopeflyer.com/artman/publish/cat_index_63.shtml

Dave Register will add to the list a lowcost EPP slope foamie that we’ve triedfor our rugged Oklahoma slope northof Dewey, OK: The Foam-One II fromMidWestSlope. A very rugged, highquality and affordable kit in the Foam-One racing format. Bounces off rocks,trees, cattle and thorn bushes. Greatfun, prompt delivery and a completehardware package.

http://www.midwestslope.com/foam-one2/

FROM DAVE GARWOOD

K-Mart Rotary Tool

Ryobi makes a motor tool that I likebetter than those made by Dremel. It’sheavier, but it’s more powerful andhas ball bearings. The problem is Ihaven’t found a place to get the Ryobitools repaired. Walking through thesandpaper aisle at K-Mart I saw theBenchtop Pro Rotary Tool (SKU07200078725, $24.96) that looked to melike a knock-off of my beloved Ryobi.It comes with a small (25-piece)assortment of fittings, and takes theDremel fittings. When I got it homeand tried it, the tool worked so welland I liked it so much that I went backthe next day to buy another to keep asa spare. Good tool; good price.

K-Mart NeatInexpensive Clamp Set(I had to get Paula her own set!)

The more you use clamps, the more ofthem you seem to need. In K-Mart Ifound a lovely little assortment of sixplastic clamps, two each of threeconfigurations called Hobby Clamps(SKU 02510434540, $7.99). When I gotit home and tried them, the clampsworked so well and I liked them somuch that I went back the next day tobuy another set. I got Paula her ownset as well. She’s always raiding myshop. It’s nigh impossible to have toomany clamps, and these inexpensiveclamps work well.

Simprop SE-300 Motor Glider

Model: Simprop Electronics SE-300Type: Polyhedral thermal duration

motor sailplaneManufacturer: Simprop Electronics

http://www.simprop.deImporter: Hobby Lobby http://

www.hobby-lobby.comWing Span: 1865 mmWing Area: 29.7 dm2Weight: 100 gramsWing Loading: 32.7 g/dm2Radio needed: 3-channel or more (Tx

must have V-Tail mix)


This is an extremely pleasant motorsailplane to both build and fly. Itcomes in a heavily prefabricated kitwith a superbly molded fuselage,wings and tail parts built and covered,full hardware included. It can be builtin a few hours as either a sailplane or amotor glider.

The builder constructs and installs theservo/battery tray and cuts off themolded nose and glues in a motormount bulkhead. Finish up a couplelittle fittings like wing incidence pinand rear wing hold-down plate; installthe controls and it’s ready to fly.

I fitted a Simprop geared, ball bearingSP-500 motor and a Simprop folding14x8 propeller. That prop was a littlescary for us sailplane guys, but itworked great, exceeding our expecta-tions for climb performance.

Climb it does! It gets small to see afterabout 10-12 seconds climb. With a thinairfoil it covers ground fast and shows

surprisingly good handling for whatlooks like shallow polyhedral breaks.Its best tricks are inside and outsideloops. On our first attempt to verifythe maker’s claim of “50 minute flighttime” Rich Loud and I got 34 minuteswith 15 climbs on a cool, cloudy, latefall day in 10 MPH wind. The SE-300 isa keeper.

Windrider BAT

I have just two flights on theWindrider Aviation BAT, a quickbuilding, fast flying, EPP-foam“plank” flying wing. The slope sail-plane builds in about three hours, andfeatures injection-molded wing halves,with servo pockets and receiver cavityand battery pocket already molded in.It’s covered with colored packing tape.

Terry Dwyer and I flew it at LakeOntario in 25-30 MPH and it justripped up the sky. The BAT had noproblem penetrating in the windyconditions and is VERY snappy inmaneuvers, pulling nearly two fullrolls per second. Regarding invertedflight performance, Terry asked,“What color is it on top?” only halfjoking. Very little forward stickpressure is needed to hold unlimitedinverted flight. Inside and outsideloops are cake.

Australian flyers report the BAT is aworthy DS trainer, although somerecommend installation of a full-span

spar. The Aussies further reportextremely wide performance from theairfoil, that the BAT excels in both full-on and light lift conditions.

The kit costs $50 from WindriderAviation in Hong Kong, and comeswith a carbon tube spar, a roll offilament tape, and two rolls of colorpacking tape.

Windrider Aviation:http://www.windrider.com.hk

Airtronics VG6000

I am in love with the Airtronics VG6000, a new-generation microprocessortransmitter WITHOUT MENUS. Thesoftware has been simplified and theLCD screen designed so that allavailable functions are displayed all thetime. Think for a minute how much“no menus” on your computer radiowill simplify your soaring life.Buy it for the flying-wing delta mixingand keep it for the six-servo unlimitedship capability. Its cost is an utterlyreasonable $200 or less from TowerHobbies, depending on which of fourservo and ESC combinations youchoose. I wrote a full review of theVG6000 in the DEC 2003 issue of FlyRC magazine. It has a couple oflimitations when compared to $500

A couple of New York Slope Dogs at the E-flight field in Scotia, NY. Dave Garwood

holds the SE-300; Rich Loud prepares to flyfor the camera. Photo by Phil Tiberio.

Simprop SE-300 in flight.

Page 11December 2003

computer radios, but nothing thatkeeps me from flying my six-servoDAW Ka-6E with it. Detailed specsand a download manual are on theAirtronics website:

http://www.airtronics.net

FROM DAVE [email protected]

My list is a little short this year. Manyneat things have already been coveredso I’ll stick to what I’ve used this year.

For DLG, the XP3 from Polecat Aero isdefinitely a winner. After severalmonths of flying, its really dialed invery nicely and has an outstandinglaunch and float capability. CheckDenny Maize’s web site for the latestprices. Wings by Phil Barnes. Excellentarticles and support on the website:

http://www.polecataero.com/

Great light weight wing servos forHLG, DLG and other small flaperon

Windrider BAT & Dave!

sailplanes are available from DymondModelSports Ltd. The Dymond D60 isa winner. Highest torque in thethinnest package for DLG that I’vefound. Excellent centering and lowdrift in a very affordable package.

http://www.rc-dymond.com/

The M5 receiver from FMA has provento be an extremely light weight, long

For a really great e-soar experience,I’m very partial to the Omega Sail-planes at NE Sailplane (Sal’s just

XP-3

range and very reliable unit. It’s one ofthe lightest full range 5 channelreceivers on the market and I’ve hadexcellent results with it. Fits great inthe nose of the XP3 but is equally athome in any 5 channel ship of any size:

https://www.fmadirect.com/site/home.htm

updated his web site - looks great andeasier to peruse!). The Omega 1.5 is myfavorite for smaller fields and lots ofeasy fun. The 2M version looks goodbut I still like the simplicity of thegeared Speed 400 on the 1.5. I’ve hadexcellent success with this little planeand recommend it to anyone:

http://www.nesail.com/

Well, if you’re going to e-soar, youneed a great place to get batteries. I’dcheck out Batteries America. I’veordered from them for several yearsnow for NiCd flight packs, 7 cell Sanyoe-soar packs and most recently a mini4-cell NiMh pack for my XP3. Goodquality, excellent delivery and they’llwire up a specialty pack and connectorif you need it. Also a good place for


cordless and cell phone batteries!

http://www.batteriesamerica.com/

I love my Great Planes Laser IncidenceMeter. It’s a bargain at $20 and hasbeen a really handy tool for sorting outthree planes that weren’t quite right.Get the incidence right, then find anywarps or misalignments. Your trim-ming and flying challenges are a loteasier after that. Check it out at:

http://www.hobbypeople.net/gallery/701602.asp

I still think the Sirius line of chargersare the best field and bench tools formaintaining the health of your flightand transmitter packs. There are sizes

for big packs and little packs, NiCdsand NiMhs. There’s even a newcharger for Li batteries. I highly

recommend the Sirius Pro Series forany serious field kit:

http://www.siriuselectronics.com/

Finally, I’ve got to put in a word forMicro Mark, my favorite tool store(well, I gotta check out the B2 refer-ence, too). The one tool I just can’t dowithout when working at the benchand at the field is a good set of hemo-stats. No, not for surgical repair ofpilots. It’s for grabbing and holdinglittle screws, nuts, etc., when yourhands are just too big or too cold or toosweaty to do the job. Also great forfishing wires and connectors out ofstrange places in your fuselage andwings. Great for popping loose nylonclevises. Also for grabbing linkages soyou can put that extra half turn on theclevis to get your trims just right.Browse a little at Micro Mark. Get acouple of straight and curved hemo-stats (the curved ones are more useful)and start finding how easy they canmake assembly and maintenance ofany of your projects.

http://www.micromark.com/

• • •


scribes the lift process correctly.)Various charts are presented to allowthe reader to get a feel for designparameters and specific flight environ-ments. From there, the importance ofthe low launch is explored and the lowlaunch concept is compared to RC-HLG. Al then very nicely expands thistopic to incorporate “performance,”flight velocity, and turn radius, and the“soaring factor.” The reader is alsointroduced to the various alignmenterrors which occur during a thermalturn, along with suggestions forproportioning which will reduce thosedrag producing errors.

Many of the ideas used to create stable,thermal-finding free flight modelstranslate very well to Al’s world. As anexample, Dutch roll, which manysailplane designers try to stay awayfrom, can be harnessed by a lowlaunch design to assist in its ability tocenter thermals nearly automatically.The Golden Age includes a spread-sheet template to simplify the designprocess.

Weight and the importance of velocityregulation make up much of the latterportion of the book. Here is where Alexplains how much elevator authorityis really needed, why large rudders arean advantage, and how to match thevertical area to the dihedral angle.

There are many interactions within Mr.Sugar’s low launch universe. The flightenvironment, aircraft span, area,weight, and control authority meetdesign, construction and pilotingabilities and skills in an intense balletwhich begins at the commencement ofthe design process and ends only whenthe aircraft is no longer in flyablecondition.

Al’s contest environment, throughwhich he evaluates sailplane perfor-mance, is incredibly simple. The rulesare included within the latter pages ofthe book, along with a large number ofhelpful hints which are sure to im-prove pilot performance in any TDevent.

While The Golden Age is focused on

(Golden Age - Continued from page 7) taking maximum advantage of theuniverse surrounding Mr. Sugar’s lowlaunch methodology, it providesinformation and ideas of use to RCsailplane designers, builders, andflyers of all types.

PDF versions of The Golden Age canbe purchased from Mr. Sugar withpayment through PayPal. The singlePDF file can be sent as an e-mailattachment (832K) for US$7.50, or on3.5 inch floppy by snail mail forUS$15.00. Please visit The Golden Ageweb site <http://www.geocities.com/simsoar> or contact Mr. Sugar directlyfor further information. And don’tforget to mention this review whenmaking inquiries or placing an order.

Al SugarP.O. Box 113315

Carrollton TX 75011-3315<http://www.geocities.com/simsoar>

<[email protected]>

• • •


This is an absolutely gorgeous originalMantis from Phil Barnes owned by Bob

Magee from Upstate New York.

My Luckenbach/Drela 130” Aegea Mantis.

Nobody who has seen a Mantis willargue that it is a unique glider,

many call it ugly. But its uniquenessgoes much further than its looks. Itsevolution is also unique and has been acommunity effort where individualshave built their own variants andinput from many flyers have influ-enced the design. It has been fun andrewarding, and, in my belief, has madethe Mantis an awesome product.

Evolution

The designer of the Mantis is TomKiesling, who got involved in soaringas a teenager. He quickly proved to bea prodigy at the hobby and I rememberhim consistently beating his betterequipped seniors with a Prophet built-up, polyhedral glider. Tom was amember of my club, Charles RiverRadio Controllers, and an activeparticipant in the Eastern SoaringLeague. As the northern-most club inthe ESL, we spend a lot of time drivingto contests as far south as Virginia. Tolimit boredom and reduce cost, wecarpool and spend a lot of time talkingplanes. On the ride back from the 1990Nationals in Vincennes, there was abig discussion on model designinspired by Mike Selig’s presentationat the awards banquet. Selig presentedsome interesting concepts on dragreduction for low Reynolds numbersailplanes. The first was the “Epplertips”. This concept was intended toreduce the induced drag at the wing

tip. The old Falcon 880 was one of thefirst models to use this concept. Itapparently did reduce the drag, butmore importantly it improved thehandling. The second concept was todroop the fuselage before and after thewing. This was intended to reduce thedrag at the fuselage/wing interface.This concept was demonstrated onSelig’s Opus and Harley Michaelis’Genie. The third concept was to use apylon mount that kept the leading andtrailing edge of the wing free. On that

trip back from the Nationals manydifferent concepts for pylon designswere thought of. Most of the ideaswere overly complex and dismissed.

The following year Tom built his firstcomposite sailplane. It used theSD8000 airfoil, lots of carbon, Epplertips, and it had a pylon! It was a pod

History of the Mantisby Anker Berg-Sonne


One of Tom Kiesling’s molded Manti.

and boom type fuselage. The pod wasmade using the lost foam method ofconstruction. The wing was boltedonto the pylon using one 1/4-20 bolt.A gasket made from a bicycle innertube was used between the wing andthe pylon. This mounting methodallowed the wing to pivot under hardlandings or other mishaps. The pylonwas tall and allowed for a one pieceflap. Although the model flew well, itwas very heavy (110 ounces). A twometer version was also made. It alsowas heavy, but flew well. Aftercampaigning these models for severalyears, new lighter versions were built.The 3 meter model was just under 70ounces and used Kevlar and glassskins. It used a similar style fuselagemade using the lost foam method.However the servos were in the tail.While simple to set up the linkages,this approach required a significantamount of nose weight adding 6 or 7ounces to the total model weight. Atwo meter version of this model wasalso made. The two-meter had theservos in the nose, and weighed 44ounces. This was a competitive weightat the time. However, the lost foammethod of construction made itdifficult to achieve a low resin contentand added several ounces.

Several years later, after a difficultwinter of health problems, Tomdecided it was time for the nextgeneration of pylon models. Since thewinter was spent recovering, Tom didnot have much time for building newmodels. A two-meter was the firstversion built. A much-simplifiedfuselage was required due to the timeconstraints. A tube was made over adowel mandrel. To hold the radio gear,a foam plug was made using a NACA4 digit symmetrical section. The plugwas glassed and attached to the frontof the fuse. The pylon was made in asimilar fashion. This approach with aKevlar skinned wing made for a lighttwo-meter at 34 ounces. This modelwas quickly named “Sherm” after itsvery sperm like appearance. The mostamazing thing about this model wasthat it was built from concept to flightin one week.

Shortly after, a 124" version was built.This version was Tom’s first attempt ata molded fuselage. Again, due to thetime constraints, the fuselage had to besimple. Cutting a 1" dowel rod in halfmade the tube plug. The pylon and

front pod were small and were cut outof a pine block. The mold was madefrom Hydra-Stone. Two completemodels were made in two weeks fromconcept to flight. The first flights wereat the 1996 Nationals, six years afterSelig’s talks. Before the model wasintroduced, it had to be named sincethe Sherm (the sperm) nick name wasquickly degrading to even less appro-priate commentary. So, the Mantisname was assigned. The Mantis wasone of the first modern models toachieve a 55 ounce weight. This isexactly half the weight of Tom’s firstcomposite model made in 1991. At thisweight the model was extremely easyto fly and even easier to land. The 7037airfoil worked very well at this weight.With 20+ ounces of ballast, the modelcould be flown in fairly heavy windswith success. This is the model thatTom used to set the record for ESLwins of 13 in 1997. It was also used byPhil Barnes as the basis for his kittedMantis.

The next iteration Mantis used a muchbetter (actually thought out) planformand the MH-32 airfoil. The span wasincreased to 134 inches. The weightwas 65 ounces. Luke Waters named itthe Super Mantis and the name stuck.This model was first flown at the 1999F3J team selections in Long Island, NY.Although Tom did not have muchsuccess at the team selection, the

model showed promise. Improve-ments were made over the next severalyears and Tom used that same designin light air conditions to make the 2004US F3J team.

Shortly after the Super Mantis camethe Molded Mantis. Jason Wernerasked Joe Wurts to design a planformfor a molded wing. Joe agreed to helpand with some performance require-ment input from Tom and Jason, hecame up with a new planform. Jasonmade his first set of molds with thisplanform and the MH-32 airfoil. Hemade a test wing and the resultslooked very promising. TerryLuckenbach ended up with the moldsand has made several wings. Tom usedone of these wings on one of Terry’sfuselages as his primary model for the2003 F3J team selection. Tom says thatJoe did a great job with the planformand the Molded Mantis is the bestlaunching model he has flown.

The Barnes Era

After seeing Tom fly his Mantis, manyESL members wanted one. Tom didnot have interest or time to build forothers, but he was willing to let otherscopy his design. A number of ESLmembers decided to build their ownand at the end of the season the firsthome-built Manti started showing up.One was Phil Barnes, who builds kits


The assembled Aegea Mantis.

The characteristic pylon andboom construction.

A close-up of the pylon from the top.Notice that the wiring comes up in thefront of the pylon. The center verticalbulkhead holds the hold-down block,

which I have covered with epoxy/filler toensure that the top touches the wing when

attached. At the back is a ballastcompartment. A comment on the need tonot leave a gap between the wing hold

down block and the wing. If you do, thebolt tension pre-stresses the attachment ofthe hold down block to the bulkhead andpylon. This is added to the stress from the

winch line under launch. I managed to pullthe wing off the fuse on a hard launch

earlier this season after leaving asubstantial gap. Fortunately the wing wasunscathed. The fuselage also appeared to

be undamaged at first in spite of lawndarting into the ground at high speed.

Upon further inspection at home Idiscovered severe delamination and broken

spars in the tail feathers. I had to replacethose. Having a backup ship removed

temptation to perform a quick field repair,which would have led to a disaster.

The pylon viewed from the side. The towhook is an L hook bought at the hardwarestore. The tow hook is 1/3” behind the CGlocation. The vertical distance between the

wing and the tow hook make the planepitch hard up if thrown straight out on a

winch launch. I have never had thisbecome a problem. I have, however,learned to throw in a more upward

direction, mainly to make my launchesmore efficient.

The airfoil at the center/tip intersection,notice the location of the flap hinge line.The flaps are actually large enough to

touch the tail boom at 90 degrees. You caneither cut the corners of the flaps or deploy

less than 90 degrees.

The tail from the top. Notice thatthe hinge line is at the 50% mark.

as a business. As soon as he startedflying it, I and many others asked himif he would be willing to make a smallrun of kits for us. Finally Phil relented,and agreed to produce a limitednumber of kits for the ESL member-ship. I made sure I got on the list earlyand during the building season of 97 to98 I received a box of four kits for theCRRC members who had ordered intime for the first run. The MantisHome Page, at http://home.att.net/~CASA/Mantis/, has a 3-view,pictures of the kits and of the finishedMantis.

The kits were very strange. Thefuselage was a stock CF tube with akevlar pod and a nose cone made on amale mold. Building the fuselage tooka lot of work. The V tails were anotherheadache. You were supposed to cut ashaped slot in the boom for the tail andthen glass it in. The major problem wasalignment of the tail to the boom.Another challenge was the controlhorns. Most of us spent hours gluingthe horns on, breaking them off andstarting over again. Compared withthe fuse the wings were a piece of cake.The center panel had a full-lengthcarbon tube as the spar, and the tipshad short length of tube to accommo-date the straight wing joiners. Thesingle flap went the whole length ofthe center panel and was controlled bya single servo.

Balancing the kit is very unusual. Youinsert all radio gear in the pod andgradually shorten the nose moment bycutting slices off the front of the boomuntil the plane balances correctly. Thelength of the tail boom is fixed. If youhave done this right you will need nonose weight.

The end result was well worth thetrouble. Most Manti came out around60 oz and flew like a dream. I spent the98 season getting used to my newMantis. There were quite a few otherManti in ESL and most of us weredelighted with them. And pretty soonthe news groups were abuzz withchatter about the new, strange gliderbeing flown on the east coast.

The weaknesses of this original designalso became apparent. The SD7037airfoil did not have great penetrationin wind. Ballasting did not work aswell as expected to improve penetra-tion and in high winds, 15 to 20 knots,


The bottom of the center section. The pieceof plywood sits on top of the pylon with a

metal bolt holding the wing on, and aplastic alignment bolt at the back. If the

wing tip impacts something the wing willrotate on the hold-down bolt and break thealignment bolt, hopefully saving the wing,and the pylon. This design feature does alot to reduce damage on hard landings,mid-airs and inadvertent tree landings.

The plane in full crow. The plane will descend vertically atmoderate speed when in full crow. High speed dives are more

fun, controlled descents less stressful on the plane.

The tail from the bottom. The “horns”are made from pushrods and the

pushrods are attached using ball joints.The pushrods themselves are carbon

fiber running in Teflon sheaths. A majorarea of innovation is control horns and

their attachment to the tails.

The Pretty Mantis fuse kit as it comes fromTerry Luckenbach. Very little work is

required to finish the fuse.

you had to be very brave, or stupid, orvery good, to venture far downwind.Another weakness emerged during thepreparations for the F3J team selec-tions. I tried a two-man tow and myouter wing panel exploded at the topof the launch. The shortness of the tubespar in the outer panel, limited by thestraight wing joiner, just didn’t give itthe strength needed to handle extremelaunch loads. Phil was at the session,analyzed the failure in detail andimmediately redesigned the tips.

An idiosyncrasy of the tube fuselage isthat the fuse twists noticeably whenrudder is applied. It looks strange tosee the tail flopping around on a winchlaunch, and normally this isn’t aproblem. Throwing the original Mantisalso was hard because the fuse was sothin. Holding the tail boom and lettinggo doesn’t work well because a gustcan easily twist the plane. The besttechnique is to throw the plane,holding the pylon at its thickest point.In addition to improving their launchtechnique, Phil and others modifiedtheir booms to improve the torsionalstiffness. This was accomplished bywrapping the boom with a bias layerof carbon fiber or Kevlar.

That winter Phil made two redesigns.He modified the outer panel design tolengthen the tube spar, moved theservo wells further out on the panels,and started kitting bent joiner rods. Healso started bagging MH32 airfoils inaddition to the original SD7037. Bothof these modifications were majorimprovements. The modified outerpanel is now strong enough to handleany launch, and the MH32 airfoilpenetrates better and ballasts betterthan the SD7037 at a small cost inminimum sink.

The Luckenbach Influence

The 2000 season also delivered a muchsimpler fuselage for the Mantis withTerry Luckenbach’s fuse. Terry’s fusesare works of art, always perfect. Theyare also much easier to build becausethe nose and pylon are finished withonly internal ply building required.Terry’s tail boom is thicker than thetube Phil used and the tail waggingeffect has been eliminated. Terry’s newfuse is now the standard for theMantis.

I built a Luckenbach MH32 Mantis assoon as the components became


available and relegated my originalMantis to backup ship status. I havesince given it to a fellow club memberwho needed a backup ship.

Early in 2001 I acquired a Sharonmoldie. Because of its bigger wingspan and greater weight it penetratedbetter and had much better L/D thanmy Mantis. It became my main contestship during the 2001 and 2002 seasonsuntil I blew it up on launch in themiddle of 2002.

The Drela Revolution

The Sharon prompted me to startlobbying for a larger Mantis thatwould have some of the characteristicsof the Sharon. Dr. Mark Drela’s airfoilsare optimized for the light wingloading of the Mantis and when Iasked him if he was willing to design awing for the Mantis he responded inless than a week with a completedesign. He continued to be superresponsive when asked to increase thespan of his design to 130". QuotingMark Drela on the design, “Unlike theprevious Mantis wing which had thesame 8.7% MH32 airfoil along thespan, the Aegea wing uses fourdifferent airfoils AG40d..AG43d alongthe span. Their thickness decreasesfrom 8.0% at the root to 6.5% at the tip,making each spanwise location well-matched to the decreasing localReynolds number. These airfoilsborrow heavily from the latest DLGairfoil technology, and respond verywell to camber and reflex. One otherunusual feature is a slight amount ofwashout twist over the middle panel ofthe 3-panel planform, which bestmitigates tip stall tendencies at slowthermalling speeds.”

Design in hand and after buyingseveral hundred dollars of spyderfoam, carbon spars, kevlar cloth and allthe other required supplies, Fritz Bien,Jan Kansky and I started buildingMark’s wing. Only Fritz completed hiswing, and then he left it leaningagainst a space heater! Fritz was ableto make the wing flyable and it doesfly great in spite of the wrinkly skin.The amount of work required to buildan Aegea wing from scratch over-whelmed me and Jan, so we startedlooking for alternative approaches.Phil Barnes was an obvious lobbyingtarget.

Phil Barnes to the rescue again

Using his tried and true constructionmethods, Phil bagged a set of proto-type wings to Mark Drela’s design andasked John Hauff from LISF to stresstest them last winter. Except for someminor buckling of the skins over theflap servo wells, the wings handled theworst John could throw at them. Theextreme thinness of the Aegea airfoilsmake it very hard to build them strongenough, and it wasn’t until Phil usedtwo carbon tube spars in the centersection that it proved strong enough.Even then, you need to strengthen theskin over the servo wells to preventbuckling of the top skin. All controlsurfaces are very large and, to avoidflap flutter from extreme launches, thecutouts should be faced with fiberglassto stiffen them.

Building Phil’s Aegea wing andTerry’s fuse was a breeze, especiallyafter I had developed a few shortcuts,and learned where the most commonmistakes were made. I had mine readyfor the start of the season and am closeto finishing a second plane. For thefirst time I’ll have the luxury ofowning identical primary and backupships.

The wing delivers what it promises. Ithas great penetration and, after tryingto ballast it, I prefer to fly itunballasted in moderate winds andwith just 5 oz of ballast in strongwinds. It weighs less than 70 oz andthe generous wing area makes it agreat floater. Landings will requiresome practice. The pitch characteristicsof the Aegea airfoil, as flaps areapplied, are unusual. Initial flap causeslarge amounts of pitch. More flapincreases pitch, but at a much lowerrate. You either need a radio that canfeed flap to elevator compensation ona curve, or you need to apply manualelevator to control pitch.

The evolution of the design in just 7years has been amazing. Every changehas been a dramatic improvement andthere is room for much more. In spiteof this, a Mantis today is an unmistak-able descendant of Tom’s originaldesign.

One strength of the Mantis is that it isboth a competitive ship and very easy

to fly. The Mantis is a reasonable planeto move up to from a trainer, and thebeginner will have a plane that will beeasy enough to fly to learn the trueskills of soaring, finding lift, staying init, and finding new lift when thethermal dies.

What next?

There are several very interestingdevelopments underway. One clubmember is mating an AVA (EasternEuropean ARF version of the BubbleDancer) fuselage with the Aegea wing.This combination will be quite a bitlighter. Also, much work is being doneon F3B and F3B derivatives of theMantis. This work is bound to influ-ence the TD version. Finally, there arerumors of a molded Mantis fromEastern Europe.

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Documents

R/C Soaring Digest - Dec 2003