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Ourlatestround up of model lyingnews.
72 PILOTS’PICTORIAL
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85 COUNTERPOINT
Aselec tion of newkit s, bits andg adgets foryou to buy
92 GOINGPLACES
Ourupd ated list of modelevent sand competitions foryou to visitoverthe next fewmonths
94 MARKETPLACE
Sell o� fyourunwanted airframesand enginesormaybe buya fewnew ones
95 NEXT ISSUE
Take alookatwhat’scominginthe July ‘25issue of RCM&E
98 PARTINGSHOT
24 BASINGSTOKEFLY-IN
Mike Freemanrepor ts from the BasingstokeMAC AllElectricFly-In2024
38 ARFREPAIRS MADE EASY
Dick vanMourikshows howtoput back together acra sh damagedAlmostReady to Flyaeroplane
44 DAFF Y’SREARGUNNER
Harr yCur zon’smodel of theDefiant interceptorhas aneattrick centred around it sreargun turret
59 USINGFOLDING PROPSASPUSHERS
Mike Freemano�fer sadvicefor when usingafolding propellertoprovide thru st on apushermodel
62 BIG UP THEINDOOR
Dave Goodenough report sfroman indoor ly-in especially arranged forthe ‘kid z’ -young andold!
80 FUNDROID
SUBS CRIBE…
andreceive Modern AerobaticTeams &HalfCentury,Baby! bookazines FREE!See page 46 fordetails
ArnaldoCorreia captures afriend’s Eadweard Muybridgemomenta she launches aBirdofTimeglider
Reviews
10 SK YHAWK
Alex Ma xfieldbuild saUKdesigned andmanuf ac turedF5L championship winningglider
68 SUPERMARINESPITFIRE
A ter lyingXFly’sprototype desert schemedmodel KevinCrozier finally managestosee sk ybelow theD-Day version’swheels!
Features
18 SPACEWALKERFLIES AGAINPar t2
Martin Hardycontinues hisconversion of aquarter sc aleSIG Spacewalkerto elec tric power
Continuing from thelastissue,Mike Bell finishesand lieshis FunFly model madefromhybridmaterials
86 GOLDEN GLOW
Neil Hall returnswithmoreadvicefor wannabeu sers of glow enginesand to gladdenthe hear ts of thosealready smit tenwithICpower
Columns
32 SCALEGLIDING
ChrisWilliamsshows howtomake reinforced butt joints before introducing hislatestgull-wing Minimoa
74 THEINSIDER
Asmall andsimplemodel givesJohn Stennard asurprisingamountof satisf ac tion
Free Pro-Plan
48 COSMIC CLOUD150
Dave Goodenough ex tr ac ts af avourite smallgliderdesignfromhis memory andenlargesitfor radiocontrol and elec tric power
Please come andjoin us.Full details canbe foundonthe event websites: https://www.interglide.co.uk/online-entr yform/ (Book here.)
https://www.interglide.co.uk/pilots/ (Check registrations andhistorical info.)
Theorganising bodyisthe British AssociationofRadio Control Soarers (a Specialist Body of the BMFA). Please contact Nick Jacksonon+44 (0)7879 654863oremail whitstable.nick@outlook.com
Thecompetitionwill be runaccording to the current F5J rules in the FAISportingCode. ‘Earlybird’ reductions areavailable forthose
booking beforeMay.Entries arelimited to amaximumof60and booking will close before16th June if themaximumisreached earlier.Any further entries will be kept on a reser ve list.
Hamilton Farm Airstrip,Bilsington,Ashford Kent,TN25 7JJisa wonderful locationwitha choice of basic or deluxecamping available Formoreinformationvisit:https://www hamiltonfarm-cl.co.uk/
Basic facilities will be available on thefield in the area outside of thefenced offCaravan Club sitebut do not include use of theCaravan Club siteshowers or toilets.Charge forbasic
WO
SK YHAWK
Alex Maxfield builds aUKdesigned andmanufactured F5L championship winning glider
Words: Alex Maxfield
Photos: Alex Maxfield, SteveHaley
Further to my article on the Encanto F5L competitionthermal soarerinthe January issue, Iplanned to review another design forthe same class and then later writeanother articlecomparingthe flight characteristics of the two. AlthoughI writethat the Encantoand theSkyhawk are competitionmodels,they areequallysuitable forsport flying.
TheF5L class allows foramainly wooden construction, twometrewingspanthermal soarerwith an electric motor forlaunching Thecompetitionrules consider the flight durationwithin aset time windowfollowed by aprecisionlanding foradditional points Theclass dictates the models canonlybe controlled with rudder,elevator andspoilers (air brakes forprecisionlanding) andis
Steve’sSkyhawk fleetshowing theX-tailand V-tail (middle) options.
commonly alsoreferred to as RES.Assuch it is probablythe most a�fordable thermal soaring class,with increasing numbers of pilots competing.
In the UK the British Association of Radio Controlled Soarers (BARCS) is the bodythat supports this andother silent lightclasses, under the watchful eyeofthe BMFA.
THEMODEL
TheSkyhawk is the brainchildofmyfriend (and competitionfield nemesis) SteveHaley. Unarguablyone of the very topthermalsoarers in thecountry,Steve is respected by many fellowcompetitorsasa toppilot in multiple FAI classes such as F5L, F5J,F3F and, in the past,F3B Stevealso lew aSkyhawk to win the 2024 UK Nationals forF5L class gliders.
TheSkyhawk has taken many monthsto perfect andisnow availablein kitformfrom SkyHigh RC.Way back in time, Stevewas
atoolmaker and, as I’ll explain later,that experiencereallyshows in thethought behind the design of the Skyhawk.
Many F5L models do look quitesimilar andoffersimilarlevels of performance
Perhaps thereisnothing trulyexotic about the Skyhawk design, with its familiarwing planformand slightlymodified AG wing section, available in cross-tail or V-tail configuration.But the main takeawayis that it ’s designed in the UK, by aUKpilot for UK conditions
Stevealso has available afuselage without amotor to competeinthe similar F3L class for bungee launch.
UNBOXING
Ipicked up the Skyhawk kitfromSteve’s home, howeverthe packaging would be quitesafein the hands of UK mail delivery companies.A nice touchisapersonallysigned label on the boxfromthe designer
Li ting thelid, atissuewrapper keeps everything together -and there’salot of stu�f in the box. Notincluded with thekit were the necessary glue, servos, motor,prop, speed controller andcovering butotherwise the kit wasverycomplete.
Theexcellent quality wood components are laser cut with great accuracy.Carbonelements forthe spars,joiners,leading edge andboom areequallyofveryhigh quality.The build is extremelywell thoughtout anddelivers a model that is robust andeasy to puttogether. It maynot be the lightest airframe, but it will stand the test of time in the handsofmost pilots
Skyhawk’s lying weightisaround550 g, ballast-able to around 1000 g, giving aweight range to match most of the UK’s lying weather. Ihavebuiltown design models significantly lighter andmost times Ihavehad to leave them in the cardue to the wind being toostrong.
POWERTRAIN SELECTION
Istuck with my go to powertrain, aDualsky 2230 motor,9 x5 GM prop andHyper light 40A ESC/BEC.Together with aGNB 3S 550 mAh LiPo these components arelight, reliable andcan deliveraround240 Wofpowertoeasily and safely haul a500 to 1000 gram modeluptothe desired height in the required time.
THEWINGS
One thing that hits youearly on is the lack of full-sizeplan. Do not let this putyou o�f; the build instructions aresuperband there are several jigs to helpyou get thebuild right.I’d go as farassaying that theinstructions andjigs
No plan required.The wing slotstogether, with the ribs spaced evenly usinga plyjig.Spanwiseweights hold it flat whilethe glue sets.
F5Lclass allows fora mainly wooden 2M thermalsoarerusing an electric motorfor launching.
TAIL GROUP
Tail components arefromhigh quality balsa, giving the right blend of strength andweight It wasa bit fiddlytoattach andthen later shape the cross grain ends to both elevator andrudder, but theydolooknice.The elevator sits on anicely formed mount that is attached to the boom. Ajig is provided fordrilling the back of the boomtoaccept the elevator andfin. This canbeadaunting task, but the jigmakes it very straightforward andguarantees goodalignment
FUSELAGE
Thefuselage is aply pod andcarbonboom assembly.The plyislight andaccurately cut, the sides andformers slotting nicelyintoplace Thewing bolts areheld by plyplatesand these arealso easy to fit in the right place.Again,a plyjig is provided to ensure the fuselage sides andformers areassembled straightand true. At themotor end Iglued in balsa fillets in all four corners in anticipationofrounding the nosetomatch thespinner radius
Ileft the boomunglued in the fuselage formers until Ihad the elevator mountglued to the boom. With the elevator bolted on and the wing inner panel bolted to the fuselage I aligned the elevator andwing andthen glued the boominplace.Later Ijiggedthe fin at 90 degrees to the elevator
Servofitment in the fuselage isquite tight
Iused the first hole on the servo armfor both elevator andrudder,but even with the relatively small throws the control movements
Carefulshaping of thenoseisneededtoblend theply andbalsa parts, allowing thecorners to be roundedso that thefolding propellerfts snugly alongthe fuselage to reduce drag.
were enough using thesupplied rudder and elevator horns. Thepushrods andtubes were feddownthe boomand exited through slots on either side of the boomatthe rear.Icarefully dripped thin CA down theinside of the boomto hold the tubes in place
Theply sides were cladinbalsa topand bottom, then theprocess of
fuselage could begin. Carefulsanding is needed to blendthe harder plytothe softer balsa but with some attentionthe corners can be rounded anda nicecross sectionachieved. This is necessary to allowthe folding propeller to fit snuglyalong thefuselage to reduce drag.
Thecanopyisretained by magnets at the rear,but Iswitched to using atape band
shaping the
Horizontal stabiliser is screwedtoa plymount
Finished cross-tail (aka X-tail)ready forcovering.
Rear of fuselage podshowing tail servoplacementsand rear wing bolt attachment point.
Anotherviewofthe back of thepod,thistimeshowing thelaminated boom support.
or sheath that slides along the fuselage from the nose andsecurely locates andretains the canopy.
BALLAST
Thereisroominthe fuselage,underthe wing, to hold around 200 goflead. Additionalweight canbeslidinside the inner panel spar. Forwing ballast, Iused steel rods weighingaround300 gintotal but cut intoshorter lengths so weight canbeincreased in stages
Whyballast at all? Whynot use some down trim to helpthe modelmoveforward in wind? It’s acommondebate. Thegenerallyaccepted rule is that ballast increases lyingspeed, so youvarythe ballast to match the lyingweight with the wind to maintainnormal lying speed withnoelevator compensation. Down elevator trim alone will adverselya�fectperformance so the model will come down quicker. When it’s windyabit of extraweight also makeslandings easier as the model is less likelytobeblown o�fcourse
I’msurethatballast andwindspeed do not have alinearrelationship but we can approximatealittle.At15mph (awindyday forF5L models) a lying weight of around 1kg is about right forthe Skyhawk (model plus full ballast. At 10 mph (usualUKweather?) around 700 gfeels about right.700 gcan be achieved with just fuselage ballast but sometimes abit of weight outboard in the winghelps to stabilise the model, especiallyifthe air is turbulent
FINISHING
My coveredand finished Skyhawk weighs around 550 grams. IknowSteve is workingon alighter versionfor those days when windand li tisreallylight,but Iwouldn’tget toohungup on the searchfor ultra-light models.Thermal soaring competitions arerarelywon by sitting intowind in ‘minimumsinkmode’. Thereis usuallysomekind of li t somewhereand the abilitytomove,find andworkli tisa much better strategy forsuccess
Alight coveringisrecommended.
IusedOralightfor the wings andtailplanes, andJap tissue anddope forthe fuselage pod.
FLYING
Steveprovidesa guide forsurface throws.He also provides arange forthe CentreofGravity, butthe final positionisusuallyarrivedatby trial anderror.Further forwardgives amore stable model, so is easier to lyand more predictable.Further back provides atwitchier model, better able to sense li tand to turn tightlywhenneeded. Istarted at apositionat the forwardend of the recommended range
Spoiler detail showingthe servoholding it fully extended.Notealsothe smallrubberbandthat ensuresthatitsnaps fullyclosedduringclimb and glide.
Single screws,front andrear, hold thewingtothe fuselage
Bare bonesofthe Skyhawkready forcovering.
Alex used Oralight forthe wings andtail, anddoped tissue forthe fuselage pod.
andthen slowlyadjusted it rearwardsuntil the model behavedhow Ilikeit.
Thepowertrain provides plenty of thrust, easilyachieving the 90-metrelaunchheight in 30 seconds,allowing forsometraversingof the sky looking forlift or shooting out left or right or downwind to something indicatinglift, suchasagliding bird. When fullyballasted the powertrain also delivers the requiredheightin the required time
Forthe maiden flight it wasacold, calm winterday.I launched intowind andSkyhawk climbed steadilyonhalfpower. Ihad disconnectedthe heightlimiter to gain more height andhavemoretime to trim the model. Asmall amount of elevator trim wasrequired. One the second flight Itried to get afeel for the effect of the spoilers on model pitch. Some elevator mix to spoiler wasneeded to maintain aslight nose down pitch whatever amount
DATAFILE
Model: Skyhawk X-tail (V-tail also available)
Modeltype: F5L/RES electric glider (F3L glider also available)
Manufacturer: SkyHigh RC https:// skyhighrc.co.uk
RRP: £275
Wingspan: 2m (78”)
WingArea: 36 sq.dm.
Weight: From 540 g
Functions: Rudder,Elevator,Spoilers, Throttle
Power: 28 mm brushless outrunner (Dualsky 2826EA)
ESC: 30 A
LiPo: 3S 500 mAh
CG: 78 -80mm
of spoiler deployment wasused, so that the spoilers canbeopened or closed with very little effect on the model, except, of course, losing height more rapidlywhen the spoilers were out
On the thirdflight,during the launch, the model picked up height with little power, suggesting liftwas present.I cut themotor at about 70 metres,circled looselyuntilI wasclose to the centreofthe thermal, then I tightened the turn andthe Skyhawk climbed slowlytoabout 150 metres.Anyonewho has experienced the same will probablyagree that thermal soaring is addictive -itstill givesmea buzz everytime!
Overall, flight characteristics were very predictable.This is an easy to flyglidersuitable forawide range of pilot skill levels.The Skyhawk turns well, senses lift well, climbs well andwhen the spoilers areout it descends well.
I’llsoonstart work on the next article, comparing the Encantoand Skyhawk. Ineed to think carefullyaboutthe metrics foruse in the comparisonand trytobeasobjective as I can. If youhaveany ideas,pleaseconnect with me through the BARCS portal andsend me a message. ■
Anyone whohas experiencedexploitingli tatlow levelwillagree that thermalsoaring is addictive.
Alex startedata CG position at theforward endofthe recommendedrange and then slowly moveditrearwards untilthe modelbehaved howhelikes it
Alex’s next articlewillcompare theEncanto previously reviewed (Jan ’25issue), in hisle thand, andthe Skyhawk.
tube bonded to the spar.The secondtube has a2 mm hole boredabout acentimetre from its outer end. Abrass M2 nut is aligned with the hole andso tsoldered to the outer surfaceofthe tube.When the tailplaneisfully assembled an M2 screwisinsertedthrough the soldered captive nut andthe hole in the tube to acorresponding hole through the carbon rod. This single screwprovides the lock to secure the tailplaneouter sections to the centresection andhence to the fuselage
An assortment of K&S square andround brass tube were usedtomakeupthe elevator drive.The system relies on the ability of atube to slide accurately intoacorrespondingstyle tube of the next larger size. Each elevator half has theinner portionofits sparreinforced to support asquare brass tube.Thistube extends about onecentimetrebeyondthe inboard end of the elevator andisepoxied andscrewed to the reinforced portionofthe elevator. Alignment of these tubes,both with the
elevator hinges andwith each other,isrequired forcorrect operationwithout binding. Both tubes areadditionallystrengthened against twistingbythe insertionofa length of ‘next size down’square tube,securedinplace with cyano.
Some so t soldering is required to make the centrefitting which transfers theelevator pushrodmovement to the square tubes on the elevator halves. In thephotonearbythe elevator pushrodconnector andthe operating lever areshownfolded lat forclarity
Theoperating lever is brass square tube.The lowerend is lattened anddrilled to takethe pin of the pushrodend fitting. Theother end of the tube is cut back andshaped to fit over the sides of another short square brass tube, one sizelarger thanthose fitted to the elevators. This jointissoldered to secure the tubes at right angles to each other
Next,two roundbrass tubes were produced These have an inside diameter su�ficient to allowthe larger square tube (just soldered) to
rotateeasilyinside it without binding. These twotubes arethen soldered to apiece of brass sheet in the positions shown. Once soldered the brass sheet holds thetubesinalignment andisepoxied to the rear face of thetailplane centresection. As each tailplane half is being fitted to the centresectionall that is required is to adjust its elevator positiontoallowits brass tube to slide intothe central square tube. This aligns both elevator halvesand connectsthem to the drive from the elevator servo.
Finally, theinboard triangularareaofeach elevator wasskinned topand bottom with 0.4 mm birchply to furtherstrengthen the vital joint between the elevator driveand the elevator itself With the tailplane/elevator assemblies completed they were assembled and checked forfull andfreemovement without lubricantapplied to showupany areas of binding. Lubricantwas applied later,once covering wascompleted, andpriortotesting of the controls
Tailplanewas builtinthree pieces.Outer sections aresupported by carbon rods fedintobrass tubesbuilt into thefuselagemounted centre section.
Tailplanelocking screwinposition.
Elevator connectionstothe centraloperating lever. Tailplanefully assembled.
Thetailplane centresectionwas placed in positiononthe fuselage,the outer sections fitted andwhole assemblychecked several times using aspirit level andtape measure to ensure correct alignment.The centrepartof the tailplane wasthen glued to the fuselage frame. Acarbonfibretube,supported mid-way down the fuselage,connectedthe elevator control armtoits associated servo
Next the fin andrudder were fitted, with the rudder post extending the full height of the fuselage frame.
TAILWHEEL
Thehuntwas then on through the ‘spares’ drawer forasuitable tailwheel anda closed loop control armfor the rudder.The result was atailwheel controlled via springs from the rudder control arm.
Tail ballast,ifrequired, canbefitted inthe bottomright-hand corner of the fuselage.The twoscrews holding the tailwheel brackettothe fuselage would be replaced with longeronesto secure the ballast
AILERONSERVOS
Attentionthen turned to the wing. Thewing needed aileron servosfitting, the wiringbeing routed to the fuselage viathe paper tubes fittedthrough the wingribs.Screw-onservo covers hadyet to be made andfitted.
COVERING THEMODEL
Thebuild proper wasnow completed,allowing covering to begin.
Thefull-sizeaircra thaveasteel tube fuselage framewith afabric covering.Inmost areasthe fabric appears to be unsupported, apartfrom whereitcontacts the steel tubes.Toemulate this balsa strips arefitted along the fuselage sides andunderside.This hadabearing on the type of covering selected forthe model aswhen the model is handled the unsupportedareas of covering could be pressed inwardsand the covering stretched. Thewing,finand tailplane likewise have areas of unsupported covering. Atextile-basedcovering wasconsidered to be the best option, preferablyalready coloured
to avoid theneed fora spray-painted finish. The ‘covering materials’ drawer of my plans’ chest produced aselectionofSolartex in various colours andsizes,enough forsmaller items but not forthe twometrespanwings or the fuselage.These required thepurchase of two rolls of Oratex. As the Spacewalker is intended foryear-rounduse colours were selected for good visibility in poorlightconditions
Thetailplane andfin/rudder assemblies were coveredfirst,using some of the longstored Solartex stock. This wasfirst checked foradhesion andshrinkage on atest piece and foundtostill be perfectlyusable.The fuselage sides andunderside were coverednext, followedbythe turtle deck behind the rear cockpit.The cockpit andtop forwardfuselage areas were le tuntil the cockpit fit outs were completeand the windscreens readyfor fixing.
Theailerons, thoughtfullycompleted by the previous owner andalready fitted with hinges, were coverednext.These were followedbythe wing underside,beforethe aileronswerefitted priortothe wing receiving its topsurface covering.
UNDERCARRIAGEFIT TING
Theundercarriage assemblywas metal primed, then painted using rattle cans.The underside of the wing wasalready fitted with groovedwooden supports as part of thewing build. These were joined at thecentreline of thefuselage butdid not takeintoaccount thewing dihedral angle.The grooveshad to be deepened towardsthe centre line forthe undercarriage to fit snugly.
Saddle clamps,mentioned in theSIG manual, hadnot materialised with the model from the lo t.These were replaced with homemade aluminiumplates andservo screws to secure theundercarriage to the wing.
ENGINE COWLING
Theplastic moulding forthe engine cowling wassupplied in twohalvesand required trimming to fit in frontofthe new battery hatch. This wasneeded to allowfor fixing screws to be positioned around therearofthe cowlingintothe firewall.
Youonlyget onechanceona job likethis! With the uncut cowling slipped into position it obscured the frontofthe fuselage,even with astronglight sourceplaced inside the cowl. Thesolutionprovedtobesticking a length of masking tape behindthe cowling, removing the cowling andmeasuring from the frontedge of the tape to thefront edge of the firewall. Measurements were taken every twocentimetres andwritten onto themasking tape.The cowl wasthen tapedinposition, aligned with the spinner and lush with the fuselage topsurface.The measurementswere then transferred to the cowl using afine point marker pen. Another length of masking tape wasused, this time with its rear edge ‘joining the dots’ from the measurements.Slight adjustments were made to keep theedge as straight as possible.Thiswas thenused as the cutting line fortrimming the plastic moulding. ADremel, fitted with acutting diskused at lowspeed, made easy work of thecuts.Further adjustments were made to enlarge theair vents on the underside of the moulding. On the IC versionthe exposed cylinder headwould have contributed to the overall cooling e�fect As this wastobeanelectric model considerationwas given to making dummy turbopropexhaust outlets,rather thanusing the supplied engine cylinder headmouldings This would have been more in keeping with the sound produced by the motor.However,as the Continental O-200 engine is such afeature of the aircra t, the supplied cylinder head mouldings were used. These were o�fset by the
Rudder andsteerable tailwheelftted.Aileron servoftted,withwiringpassing throughthe tube to thefuselage.
Shaped cowl showingmeasurementsand cutline.
