bushby mustang ii aircraft performance report - CAFE Foundation

MUSTANG II APRand proven aircraft design. It seemedlike an excellent candidate for a CAFEAPR. Judging by the enthusiasm exhibitedby Jim Lewis, the owner, itwas obvious that he had enjoyed hisassociation with this airplane.The previous owner, Art Beer, wason hand to greet Jim when he arrivedat the CAFE hangar. It was at thattime I realized that I had flown thisplane briefly several years before.We held the standard acceptanceinterview with the owner regardingthe various specifics about the plane’shistory, any modifications, restrictionsor unusual characteristics.Meanwhile, the technicians of theCAFE Foundation prepared the planefor its first flight, a subjective evaluationin which various features such ascockpit layout, ground handling, servicing,field-of-view, inflightequipment, and flying qualities areevaluated in detail.The plane was defueled and itsempty weight and c.g. were determined.A video camcorder with a linkto the aircraft intercom was installedto monitor my comments and the instrumentpanel readouts. The CAFEBarograph was not installed on theflying qualities flight so as not to alterthe plane’s characteristics.ACCOMMODATIONSN 402C seemed to be built with apurpose in mind. It is a day/VFR fun,fast airplane. It has nothing installedthat is not required to meet that mission.There is no heater, defog, orlighting system installed. Therefore, itis light, simple, and has very good performance.The rollover bar, that alsoserves as the windshield canopy bow,is very sturdy and would provide excellentprotection to the occupantsshould the aircraft end upside-down.The standard canopy locking systemconsisted of a twist lock at the topcenter of the canopy bow to keep thecanopy from sliding aft on the rails.This was further modified with threeovercenter canopy latch mechanisms.These latches were located at top centerand one each behind the seat oneither side on the canopy rail. Theselatches added to the security of thecanopy in flight but seemed difficultto operate and, in an emergency situation,would very likely hamper egressfrom the cockpit.N402C’s main gear fairing (top) and non-faired tailwheel (bottom). The centerphoto shows a Mustang II with stall strips and brake fairings.FIRST FLIGHT IMPRESSIONS

SPECIFICATIONS N402CEmpty weight, no oil/gross weightPayload with full fuelUseful loadENGINE:Engine make, modelEngine horsepowerEngine TBOEngine RPM, maximumMan. Pressure, maximumTurbine Inlet, maximumCyl head temp., maximumOil pressure rangeOil temp., maximumFuel pressure, rangeWeight of prop/spinner/crankInduction systemInduction inletExhaust systemOil capacity, typeIgnition systemCooling systemCooling inletCooling outletPROPELLER:MakeMaterialDiameter/pitch @ 75% spanProp extension, lengthProp ground clearance, full fuelSpinner diameterElectrical systemFuel systemFuel typeFuel capacityFuel unusableBraking systemFlight control systemHydraulic systemTire size, main/tailCABIN DIMENSIONS:SeatsCabin entryWidth at hipsWidth at shouldersHeight, seat to headlinerBaggage capacity/sizeBaggage door sizeApproved maneuvers:CENTER OF GRAVITY:Range, % MAC, inchesforward limit, in. from datumEmpty weight c.g., by CAFEFrom datum locationMain landing gear moment armTailwheel moment armFuel tank moment armFront seat occupants moment armMUSTANG II APRMUSTANG II N402CEstimated Cost: $10,780 for the basic airframe withoutengine/prop/instruments/paint/lightsHours to build: 2500 hours/9 years Completed: 1985983.25 lb/1500 lb314.5 lb516.75 lbLycoming, O-320 E2D160 BHP2000 hr2700 RPM29 in HgNA500° F25-100 psi245° F.5-8.0 psi77.2 lbMA4-SPA carb, bottom mount8.75 sq incrossover, stainless, no muffler,exit nozzles8 qt, 15W-50Slick 4271/4270Pitot inlets, downdraft50 sq in40.5 sq inFixed pitchPacesetterMaple, 5 laminations68 x 66 in4 in8 in12 in40 amp Nippondenso alternator1 tank in forward fuselage, gravity91 octane25 US gal1 ozCleveland discs, single caliperDual center sticks, push-pull tubes, rudder cablesNA5:00 x 5, 6 x 22 R&K tailwheel2sliding canopy38 in37.5 in33 in75 lb/10”L x 30”W x 27”HNoneAt 1350 lb, fully aerobatic including loops, rolls,hammerheads, spins, inverted flight with properoil system16% to 28% MAC, 5.88 in64 in69.15 inforward tip of spinner61.55 in232.05 innanaI consider my first impressions ofan airplane’s flying qualities to be importantto the evaluation. Afterseveral flights a pilot will learn to accommodatean item that is initially anirritant. By doing the subjective evaluationon my very first flight, morecan be discerned.GROUND OPERATIONSGround handling of the plane wasvery nice. Its light weight allowed foreasy pushing and the tail could easilybe picked up for maneuvering in tightspots. Moving the plane backwards onthe ground required the picking up ofthe tail, which was not difficult, sinceit weighed about 40 pounds.Start up was quick and easy, requiringonly a few pumps of the throttle.The warmup and ground operationswere routine.All pre-takeoff checks were accomplishedroutinely although noorganized written checklist was provided.The light weight of the woodenpropeller was evident by the quick accelerationfollowing throttlemovement.Braking was effective for slowingand turning sharply in parking spots.The non-swivel tail wheel was positiveand very sensitive while taxiing. I feltit was too sensitive, causing quickmovement, and required constant attentionto taxiing direction.Tail-wheeled airplanes traditionallyhave field of view restrictions on theground, however this one showed agood wide field of view over the nosewhile taxiing.TAKEOFF AND CLIMBOnce cleared for take-off the powerresponded quickly and accelerationwas swift. Directional control ontakeoff was positive except that someoversensitivity of the tailwheel wasevident. Once the tailwheel lifted off,the directional control settled down tobeing very nice. Pitch and roll controlswere positive and precise, makingit easy to attain and hold the desiredclimb attitude.Climbing at full throttle while indicating120mph showed an initial rateof climb of 2000 fpm indicated on thepanel’s VSI. The view over the noseduring the climb was adequate to seeany obstacles. A transparent greenplastic sun block had been installedover the pilot’s head for greater com-

fort on sunny days. With a little practice,the view through this wassufficient to see other traffic.In this Mustang II the oil temp consistentlyran below 180 degrees. Evenafter sustained periods of slow flightthe temperature only came up to 185degrees. No cowl flaps are available,nor do they seem necessary. No climbcooling test was performed.STATIC LONGITUDINALSTABILITYUpon leveling off at 7,000’ and 120mph IAS the first task was to explorethe static longitudinal stability. Withthe airplane trimmed to 120 mph ahand-held stick force gauge was usedto measure the elevator force requiredto hold level flight. Each airspeed, in10 mph increments throughout theentire speed range, was evaluated byadding or reducing power as necessaryto alter the airspeed. The elevatortrim remained unchanged throughoutthis test. The greater the incrementalforce at each successive airspeed thegreater the static stability. Havingflown a variety of other similar airplanesand previously submittedreports on the RV-6A and the Tailwindit is my opinion that the MustangII has one of the best stick force gradientsfor all-around flying. See Figure1.DYNAMIC STABILITYDynamic stability, short period, inboth stick-fixed and stick-free modeswere explored. A sampling of all airspeedsacross the entire operatingrange were tested in both modes. Theresults were completely ‘deadbeat’, inthat when pitch doublets were inducedand the stick was then let free,no pitch oscillations or overshoots resulted.This is evidence of the idealdynamic stability qualities with thisdesign.I was unable to fully trim the elevatorto airspeeds below 110 mph IASdue to the limited travel of the electricelevator trim system.SPIRAL STABILITYMUSTANG II APRNormally my evaluation of spiralstability would be done at both 90 &120 mph IAS, however, due to the inabilityto fully trim the elevator to 90mph I could only evaluate its performanceat 120 mph. After carefullytrimming and stabilizing in a 30 degreebank turn, the controls were releasedat which time I observed thebanking tendencies. After more than40 seconds of continued turn with nochange in the bank attitude, the testwas terminated. The Mustang II thusexhibited neutral spiral stability inboth directions. A feature such as thiswould be beneficial to a pilot duringmoments of inattention. The MustangII gives the feel of lightness on thecontrols, yet is not an airplane thatyou have to watch constantly to keepit under control in bank. The airplanetends to stay in the existing attitudeunless control inputs cause it tochange.ROLL DUE TO YAW86420-2-4-6-8Tailwind, 120 IASCessna 152, 100 IASMustang II, 120 IAS70 90 110 130 150 170IAS, mphFigure 1.Static Longitudinal StabilityTrimmed hands-off at VaRoll due to yaw, at Va and 1.5Vso,was examined by inducing steady stateyaw with the rudder and observing thebank required to hold the airplane ona constant heading. The results weresimilar at both airspeeds examined(90 & 120 mph). half rudder deflectionrequired 8-10 degrees of bank tohold a constant heading. Full rudderdeflection required 15 degrees of bank.The 90 mph test was repeated withfull flaps extended. Here, only 5 degreesof bank with half rudder, and 10degrees with full rudder deflectionwere needed.Another way to look at the roll dueto yaw or dihedral merits of an airplaneis to observe the bank whileinducing yaw with the rudder (handsoff the ailerons). This plane shows astrong and positive tendency for thebank to follow the yaw input. Withrudder alone the bank could be controlledfrom 30 degrees of bank in onedirection to 30 degrees bank in the oppositedirection. It was during thesechecks that I noticed that the airplaneexhibited a stronger than normal tendencyto oscillate in yaw. I decided tofurther investigate this during theDutch roll check later in the flight.ADVERSE YAWAn adverse yaw estimation wasmade by slowing to 80 mph and, usingfull aileron, observing the hesitationLarry FordThe cowl exit area was reduced by70% to cut cooling drag.

MUSTANG II APRPowerDrawof the heading at the onset of the turn.With the short wingspan and quickroll it responded as anticipated withvery little adverse yaw. Even the mostdramatic aileron inputs yielded only 5degrees of heading change opposite tothe roll input.ROLL PERFORMANCERoll rates were also measured at120 mph through the use of a wiregrid attached to the instrument paneland a stop watch. The right to left rollrate was 72 degrees per second, whilethe left to right rate was 66 degreesper second. Figure 2 compares theroll performance of other aircraft wehave tested.DUTCH ROLLDutch roll was examined by inducingdoublets in yaw, pitch, and roll.Upon release of the controls the oscillationcontinued much longer thannormal for an airplane that had justexhibited such otherwise strong stabilitycharacteristics. Upon furtherexploration I found that with rudderalone I could excite yaw oscillationsthat would continue for as many as 15overshoots. At no time was it severeenough to present any danger. It wasjust that the directional stability wasnot as strong as it was in roll andpitch. The oscillation could be easilycontrolled with the use of the rudderas a yaw damper. It exhibited noDutch roll tendencies.STALLSThe stall sequence was very interestingto evaluate. At 1300 rpm, toapproach the stall slowly, the airspeedwas reduced while looking for any signalof an impending stall. There wasno electronic stall warning system installed.In flaps up configuration, thestall occurred a b r u p t l y with virtuallyno aerodynamic buffeting or warning.The nose just crisply and abruptlypitched down with mild left wingdrop. The recovery was instantaneouswith the release of the stick back-pressure.Several stalls were made withexactly the same results each time.The 60 mph panel indication of stallwas consistent but will be checked forROLL RATE, degrees/secondSpeed, IASRV-6ATailwind W10Cessna 152Mustang IIVa80474772Figure 2. Roll rates include theaileron input time.1.3 Vso364534naBrien Seeleyaccuracy on later CAFE flights.Flaps were extended for comparisonof the landing stall characteristicswith those of the clean stall. It wasdifficult to fully extend the flaps to thethird notch until the airspeed was below85 mph. The handle could bemoved to the proper position but itwould not lock into the notch and stayextended. The stall with full flaps occurredat a panel indication of 63mph, 3 mph higher than with no flaps.The abrupt pitch down and left wingdrop were very similar to that of noflaps.Since the higher airspeed puzzledme, I checked the stall speeds at allflap settings. With two notches thestall was 61 mph and with one notchit was 60 mph. The quick recoveryand very predictable nature of the stallcharacteristics are pleasant and not aworrisome thing at all. However, ifone desired the buffeting stall warningof some of the production aircraft, thisplane would need some added devicesto create such warning.Without the barograph and otherinstrumentation installed, a maximumspeed run was made at 7,500’ for latercomparison with the instrumentedflights. The maximum IAS was 178mph @ 2750 rpm.MANEUVERING STABILITYFigure 3 shows a graph of the maneuveringstability or stick force per Gobtained. This is a measure of how

much tacttile feedback is provided tothe pilot relative to the wing loadingsbeing produced by the pilot’s force on3025201510501 1.5 2 2.5 3Figure 3. Maneuvering Stability@Va with mid to forward c.g.RV-6AForce in G'sTailwindMUSTANG II APRCONCLUSIONMy final subjective flight is to determinethe suitability of the plane forthe continuation of the CAFE APR.This seems like an excellent choice.One interesting note is that this is ourfirst test aircraft that was not “new”.This airplane has been owned by threeEAA members, each adding their owntouches, and it has been in continuoususe facing the rigors of life on theflight line. It is in excellent conditionand has been obviously well cared-forby its owner, Jim Lewis.IMPORTANT NOTICEThe purpose of this report is to provideto prospective buyers of homebuiltaircraft a body of informationthat can help them select the type ofaircraft that is best for their needs.These reports may aid in estimatingthe incremental gains in performanceor flying qualities that result from theapplication of various types of aircraftmodifications to a given aircraftdesign. It must be emphasized thatthis information is not intended toserve as a Pilot’s Operating Handbookfor the operation of any aircraft.Every effort has been made to obtainthe most accurate information possible.The data are presented as measuredand are subject to errors from avariety of sources. The flying qualitiesevaluation represents the opinionsof the reporting test pilot.Cessna 152Mustang IIthe stick. Comparison is made to theother aircraft tested thus far and revealsthat the Mustang II has a goodlevel of stick feedback relative to theothers.APPROACH AND LANDINGAfter more than an hour of verypleasant flying in an enjoyable airplaneit was time to return to see itslanding qualities. With the nose downthe speed would build quickly due primarilyto the clean aerodynamicexterior. With the excellent visibilityand fine maneuverability it was easyto manage the flight path in the trafficpattern. Downwind was flown at 100mph slowing to 90 mph on final, furtherreducing to 80 mph in the flare.Keeping in mind the small value theflaps had in reducing the stall speedmy first landing was planned to useonly the first notch of flaps; however,with the low drag that this settingproduced it was difficult to maintainthe desired glideslope. Therefore,flaps were reset to the third notch.The touchdown and landing werestraightforward and comfortable. Athree point landing was made withonly a small crosswind evident fromthe wind sock. The still too-sensitivetailwheel gave plenty of authority tocontrol the direction during the rollout.Any reproduction, sale, republication,or other use of the whole or any partof this report without the expresswritten consent of the ExperimentalAircraft Association and the CAFEFoundation is strictly prohibited.Reprints of this report may beobtained by writing to: SportAviation, EAA Aviation Center, 3000Poberezny Road, Oshkosh, WI.54903-3086.A C K N O W L E D G E M E N T SThe CAFE Foundation gratefullyacknowledges the assistance of JimLewis, Art Beer, Ted Hendrickson,Anne Seeley, EAA Chapter 124, theSonoma County Airport FAA ControlTower Staff, and several helpful peoplein the engineering department atAvco-Lycoming.SPONSORSExperimental Aircraft AssociationAircraft Spruce & Specialty Co.Virtual VisionTrimble NavigationMentor PlusWeigh-TronixFluke CorporationTerra CorporationB & C Specialty CompanyEngineered SoftwareAir TabsHexcel CorporationBall VariometersBourns % Son Signs