Review of the July 2004 Flying Wing workshop - Mat's

On the ’Wing...by Bill & Bunny KuhlmanJim Marske has been designingand building full size taillesssailplanes for nearly fifty years,beginning with his XM-1 whichfirst flew in September of 1957.The evolution of the XM-1 to thePioneer II took a number of yearsand several prototypes, but theevolution of Jim’s design did notstop there. The fundamentalplanform has now been used asthe basis for the Pioneer III (avery much updated Pioneer II-D),currently nearing completion, thePioneer IV (15 meter span), andthe Pioneer V (16.6 meter span),a two place side-by-side trainer.Since Bill attended a workshop atMarske Flying Wings in 2000,we’ve been keeping abreast of thehappenings at Marske FlyingWings by visiting the web site.Bill noticed a “flying wingdesign” workshop announcementon the web site early in 2004 andwas seriously consideringattending. Plans were quicklyfirmed up when Mark Nankivilexpressed an interest in attendingas well.The plan was for Bill to fly fromSeattle to St. Louis, and for thetwo to take off on a road tripthrough Muncie (via the AMAMuseum) to Marion Ohio, with aside trip to the Air force Museumon the return. The entire trip wentsmoothly, and some of Mark’sphotos from the Air ForceMuseum have already appearedin RCSD. (See the CG-4A photosin the September 2004 issue.)The workshop took place over theweekend of July 17-18 at theMarske facility near the Marionairport. Participants included anaerodynamicist, a couple ofcomputer code writers/softwareengineers, a test pilot, and severalothers with an interest in kitplanes, both as private venturesand with an eye to kit production.Mark and Bill were the onlymodelers in attendance.Mat Redsell lead the workshopand valiantly tried to follow thepredetermined schedule of topicswithin the allotted time. As isusual with this sort of group, itwas natural for participants tolink one subject to another andbecome so entirely engrossed inthe path of conversation that itwas extremely easy to lose trackof time. Although we nearlyalways gave out groans as Matbrought us back on track, Markand Bill both agreed the weekendwas an excellent blend of short“lectures” by Mat, Jim, or one ofthe attendees, and relaxedconversations whererepresentatives of the variousdisciplines could interact at will.The “icebreaker” was adiscussion focused on themisconceptions about taillessaircraft — instability, a tendencyto tumble, complicated controlsystems, etc. Each of these wasdispelled in turn by relating theexperiences of Jim and Mat withthe Pioneer II-D with photo orvideo tape evidence.The Marske planform was thenpresented as a safe, economicalmethod for achieving exceptionalperformance given its class andconstruction materials. Again,everything was supported withphotos and videos, then Matbrought out the spreadsheets.January 2005 1

From there, the presentationmoved on to the actual designprocess. This is the one areawhere the expertise of modelersturned out to be invaluable to theongoing discussion. Compared tothose involved with full sizeaircraft, modelers tend to design,build and fly a much largernumber of aircraft over a giventime span. This provides anenormous body of first handevidence for what does and doesnot work in practice. And Markand Bill had arrived with a largemental store of ideas fromtechnical papers, magazinearticles, and personal experienceregarding tailless planforms.The last portion of the workshopinvolved the future of taillessaircraft. Projected improvementsin design and construction, andthe advances in performancewhich are expected to result,were balanced with theacceptance of tailless aircraft bythe public/consumer.Mark and Bill came away fromthe workshop with a number ofideas for tailless designs,predominantly involvingplanforms with quarter chordlines which are perpendicular tothe aircraft centerline or slightlyswept forward.As mentioned in prior columns,such a planform, with taper,provides a large arm for theelevator function and moves theailerons to a position closer to theCG, allowing use of differentialwithout adversely affecting pitch.If the aspect ratio is held to underten, stall characteristics are quitebenign and the Reynolds numbersare larger. Additionally, taillessaircraft of this type are quiteeasily constructed, can be verylight, and can be designed to haveminimal drag. All of this meansan expanded speed range, ease ofcontrol, and excellent thermalability.Mat, until recently, had beenflying his Monarch and thrillingin his ability to thermal well invery small areas of lift. Whenflying the Monarch, the pilot isalmost entirely out in the open,and subject to feeling the airwarm and cool, smelling thepollen being lifted by thermals,and having to wipe spider websfrom his or her glasses. Matexplains that flying the Monarchis the closest thing to actuallybeing a bird that one can imagine.Jim flew his own Monarch atHarris Hill a few years ago andsurprised everyone with a flightMat Redsell takes his Monarch up on auto tow. This launch methodis quite inexpensive. A strain gauge readout visible to the drivermakes sure the line tension remains consistent.Photo by Bill Kuhlman taken during the May 2000 workshop.2 R/C Soaring Digest

Mike Couts at the controls as the Pioneer II-D starts its aerotow toaltitude. This ’ship originally belonged to Lloyd Watson who hadpurchased it in nearly complete form from another owner. TheMarske Flying Wings team rebuilt the entire aircraft. The wingsurfaces were contoured to match the original airfoil and thefuselage underwent some modifications, including addition of anose wheel. Wing tip extensions were added, increasing the wingspan to just over 15 meters. Not readily apparent in this photo arethe fences which separate the inner edge of the elevator from thefuselage fillet. This addittion nearly eliminated the separatedturbulent flow at the aft end of the fuslelage. Photo by Bill Kuhlman/in excess of four hours from areasonable launch height.Jim and Mat have recentlyexperimented with a moveableCG for the Pioneer II-D. Thisopens even more vistas, as trimdrag is substantially reduced. Aten pound weight has beeninstalled, and it travels the lengthof the fuselage inside a tube,pulled along by a continuouscable attached to a rotary dial.The weight is slid forward forhigh speed cruising, to the rearfor thermalling.When Mike Couts landed thePioneer after the workshopdemonstration flight, it seemedlike the rollout was extremelylong. Mike later related that oncethe nose wheel touches theground, the glider just continuesto travel in a straight line, and it’seasy to run off the runway if theaircraft is canted on landing dueto a cross-wind. When the mainwheel touched the ground, Mikehad simply moved the weight tothe extreme rear of the aircraftand was able to hold the nosewheel off the ground for anextended run. Rudder authoritywas good enough that he couldsteer the aircraft down nearly theentire length of the runway.Was the workshop worthwhile?Bill and Mark agree they learneda lot from the workshop,particularly because of the varieddisciplines involved in thefrequent discussions both duringthe workshop and during breaks.Additionally, watching theadvanced Pioneer II-D fly was anawesome experience.Mark is currently in the laststages of designing a TD ’wingwhich he hopes to campaign inlocal contests, and Bill is ready tostart building two competitionaircraft for the 2005 Visalia Fallfestival — a two meter and anunlimited.The one other item which Markand Bill agree on is the need forscale models for preliminaryflight testing of a new design andthe desire to construct scalemodels just because it’s so cool tobe flying the closest thing to a fullsize aircraft without leaving theground. In fact, Marske FlyingWings is well on the way tobuilding a quarter scale PioneerIV. And a future “On the’Wing...” column will give detailsof the Monarch G, in hopes anR/C Soaring Digest reader willtake on the challenge.Until next time...January 2005 3

The Pioneer III takes shape at Marske Flying Wings in Marion Ohio. This is howthe airframe appeared in July 2004. Both photos by Mark Nankivil.Left: The fuselage consists of a welded steel tube internal frame and a fiberglassshell. The canopy will be hinged from the front. When the photo was taken, theinstrument panel was cut out and in place. The rudder was constructed but wasnot attached. As is in keeping with what we have seen as a trend, the airfoil hasminimal reflex and the pitching moment is only slightly positive.Right: The wings are resting in plywood cradles, leading edge down. Jim Marske’s Monarch wings serve as a backdrop. Notice the wing tips carrythe same elliptical leading edge planform as the new tips which have been installed on the Pioneer II-D. The ailerons are fabricated but notisntalled as yet. The aileron and air brake pushrods are in evidence. The ribs are specially corrugated fiberglass with lightening holes cut out. Thefabrication of the Pioneer III owes a lot to a prior building project, an essentially all carbon Monarch. The weight savings and additional strengthmade a big impression on the team, and a good portion of the technology was transferred to the fiberglass composite Pioneer II design.Opposite page: The highly modified Pioneer II-D on tow over the Marion airport. The Pioneer behaves in excellent fashion when using the bridlesystem. Positioning relative to the tow aircraft wake is not critical. Photo by Mark Nankivil.Page 30: Mike Couts brings the Pioneer II-D in for a smooth landing. Photo by Bill Kuhlman4 R/C Soaring Digest

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