TRIAVIATHON TROPHY CAFE FOUNDATION PRESIDENT Brien Seeley VICE PRESIDENT Larry Ford TREASURER C.J. Stephens SECRETARY Daniel Wayman TEST PILOT C.J. Stephens DIRECTORS Crandon Elmer Otis Holt Jack Norris Gris Hawkins Stephen Williams Ed Vetter CHALLENGE TROPHY AIRCRAFT PERFORMANCE REPORT Sponsored and Funded by the Experimental Aircraft Association and the Federal Aviation Administration Glasair III BY BRIEN A. SEELEY, CJ. STEPHENS AND THE CAFE BOARD T he fastest aircraft tested thus far in the CAFE Foundation and EAA Aircraft Performance Report program, the Glasair TTI is a high performance design. The prototype first flew in 1986. It was designed in the mid 1980's by Tom Hamilton, Ted Setzer, Bob Gavinsky and others at Stoddard Hamilton Aircraft, Inc., the kit manufacturer. Lyle Powell also offered significant input in the design. An all-composite, kit-built, low-wing aircraft, the Glasair III uses tri-cycle retractable landing gear and a 300 horsepower Ly- coming IO-540-K engine. Originally flown with a 23.3 foot wingspan, a later factory option offered wingtip extensions giving a 27 foot wingspan. Bill Stamm, an in- dependent supplier, offered alternative wingtip extensions for a 25.8 foot span. These lat- ter were adopted by Bob Herendeen for his airshow aer- obatic version of the aircraft in order to enhance its climb and tight turning abilities. The Glasair III kit includes pre-molded fuselage skins, wing skins, spars, cowling and empennage made of fiberglass and Derakane vinylester resin. It also contains complete hard- ware for the entire aircraft structure including controls, fasteners, weldments, landing gear system, engine mount, windshield, etc. Stoddard Hamilton Aircraft receives high praise from their builders for their technical support. They provide a well planned, detailed Construction Manual and thorough Pilot's Operating Handbook with the kit for each aircraft. A PERFECT CANDIDATE Chuck Hautamaki's Glasair III, N313CH, was selected for flight testing because of its lightweight, stock, plans-built airframe with an unmodified 34 FEBRUARY 1997
Transcript
TRIAVIATHONTROPHY
CAFEFOUNDATION
PRESIDENTBrien Seeley
VICEPRESIDENT
Larry Ford
TREASURERC.J. Stephens
SECRETARYDaniel Wayman
TEST PILOTC.J. Stephens
DIRECTORSCrandon Elmer
Otis HoltJack Norris
Gris HawkinsStephen Williams
Ed Vetter
CHALLENGETROPHY
AIRCRAFT PERFORMANCE REPORTSponsored and Funded by the Experimental Aircraft Association
and the Federal Aviation Administration
Glasair IIIBY BRIEN A. SEELEY, CJ. STEPHENS AND THE CAFE BOARD
The fastest aircraft testedthus far in the CAFEFoundation and EAA
Aircraft Performance Reportprogram, the Glasair TTI is ahigh performance design. Theprototype first flew in 1986. Itwas designed in the mid 1980'sby Tom Hamilton, Ted Setzer,Bob Gavinsky and others atStoddard Hamilton Aircraft,Inc., the kit manufacturer. LylePowell also offered significantinput in the design.
An all-composite, kit-built,low-wing aircraft, the Glasair IIIuses tri-cycle retractable landinggear and a 300 horsepower Ly-coming IO-540-K engine.
Originally flown with a
23.3 foot wingspan, a laterfactory option offered wingtipextensions giving a 27 footwingspan. Bill Stamm, an in-dependent supplier, offeredalternative wingtip extensionsfor a 25.8 foot span. These lat-ter were adopted by BobHerendeen for his airshow aer-obatic version of the aircraft inorder to enhance its climb andtight turning abilities.
The Glasair III kit includespre-molded fuselage skins,wing skins, spars, cowling andempennage made of fiberglassand Derakane vinylester resin.It also contains complete hard-ware for the entire aircraftstructure including controls,
fasteners, weldments, landinggear system, engine mount,windshield, etc.
Stoddard Hamilton Aircraftreceives high praise from theirbui lders for their technicalsupport. They provide a wellplanned, detailed ConstructionManual and thorough Pilot'sOperating Handbook with thekit for each aircraft.
A PERFECTCANDIDATE
Chuck Hautamaki's GlasairIII, N313CH, was selected forflight testing because of itslightweight, stock, plans-builtairframe with an unmodified
34 FEBRUARY 1997
KIT SUPPLIERStoddard Hamilton Aircraft Corp., Inc.
18701 58th Ave. NortheastArlington, WA. 98223.
360/435-8533 FAX: 360/435-9525
OWNER/BUILDER N313CHChuck Hautamaki, HM# 154839
6425 W 35th St.Loveland, CO. 80538
970/203-0037 FAX: 970/203-0071
DESIGNER'S INFORMATIONCost of kit, no engine, prop, avionics, paint $36,980Plans sold to date 320Number completed 120Estimated hours to build, from prefab kits 2000Prototype first flew, date 1986Normal empty weight, with IO-540 Lyc. 1625 lbDesign gross weight, with IO-540 Lyc.Recommended engine(s)Advice to builders:
2400 lb/2500 lb with long wingLyc. IO-540-K1G5D, 37° left rear induction
Keep it light, stick to the plans, join a buildergroup and read the factory newsletter updates.
CAFE FOUNDATION DATA, N313 CHWingspan 23 ft 3.5 in/27 ftWing chord, root/tip, short wing 50.5 in/ 33" at tip jointWing area, short/long 88 sq ft/97.23 sq ftWing loading, 2400 lb/88 sq ft or 2500/97.2 27.27 lb/sq ft /25.7 lb/sq ftPower loading, 2400 lb/300 hp short wing 81b/hpSpan loading, short/long 103 lb/ft /95.6 lb/ftAirfoil, main wing LS (1) 0413 root, tipAirfoil, design lift coefficient .04Airfoil, thickness to chord ratio 13%Aspect ratio, span2/ sq ft 6.67 short, 7.64 with long tipsWing incidence +2.3°Thrust line incidence, crankshaft 0°Wing dihedral 6°, (3° per side)Wing taper ratio, root/tip, short wing 53.84 in/33 in = 0.61Wing twist or washout 0°Wing sweep 0°Steering differential braking, toe brakesLanding gear electro-hydraulic retractable, tricycleHorizontal stab: span/area 104 in/16.25 sq ftHorizontal stabilator chord, root/tip 28/17 inElevator: total span/area 104 in/5.69 sq ftElevator chord: root/tip 9.75/6.0 inVertical stabilizer: span/area incl. rudder 51.5 in/ 11.4 sq ftVertical stabilizer chord: average 31.75 inRudder: average span/area 51.5 in 6.1 sq ftRudder chord: bottom/ top 23/11.25 inAilerons: span/average chord, each 42/6.87 inFlaps: span/chord, each 69/9 inTail incidence 0°Total length 21 ft 4 inHeight, static with full fuel 7 ft 10.5 inMinimum turning circle naMain gear track 10 ft 2 inWheelbasc, nosewheel to main gear see Sample c.g.'sAcceleration Limits +3.8/-1.0 at gross weight, +6/-4.0 at 2120 lbAIRSPEEDS PER OWNER'S P.O.H., IAS
Never exceed, Vne 291/335 kt/mphManeuvering, Va 174.5/201 kt /mphBest rate of climb, Vy 113/130 kt/ mphBest angle of climb, Vx 87/100 kt/mphStall, clean, 23.3' span, 2120 lb GW, Vs 74Stall, dirty, 23.3' span, 2400 lb, GW, Vso 78Stalls, 27' span 6 mph less than 23.3' spanFlap Speed, full 45°, Vf 121.5/140 kt/mphGear operation/extended, Vge 121.5/140 kt/mph
engine. It also was skillfully built tobe straight and very smooth. Its enginehad only 130 hours since overhaul andhad recently shown 78/80 compres-sion on all cylinders. Ted Setzer andTim Johnson of Stoddard HamiltonAircraft, Inc., concurred with the se-lection of this privately owned aircraftand assisted in this report by providingengineering data about the design.
The equipment list of N313CH in-cluded a King KX-155 navcom, KingKT-76 transponder, intercom, VisionMicro engine instruments, and an 18lb automatic engine fire extinguishersystem.
Chuck acquired his Glasair III kitsecond hand from its original purchaser,Clark Pollard, an American Airlines pi-lot from San Mateo. He built it in hisbasement in Minnesota. He receivedexcellent technical support from Stod-dard Hamilton Aircraft, after paying anominal transfer fee. "They treated mevery, very well." He built the III in hisbasement, alone, except for some helpwith the wing closure, engine overhauland sewing of upholstery.
When Stoddard Hamilton changedto a graphite stabilizer on the GlasairIII to achieve more flutter margin,they sent out new stabilizers to theirbuilders at no charge. Chuck said, "SHalso lightened up their parts substan-t ia l ly shortly after I got my kit, byimproving the bagging process."
This aircraft had only three smallchanges from the plans; a slightlysmaller induction air inlet, a slight re-contouring of the landing gear doors,and the use of a fixed rather than ad-justable cowl exit size.
After making the necessary flighttest preparations, Chuck and his son,David, flew his Glasair III to theCAFE Foundation's test facility inSanta Rosa from his home base inLoveland, Colorado.
Chuck's Glasair III was tested withboth the original 23.3 foot wingspan,and then with the 27 foot wingspan.Each long wingtip weighed 10.9 lbs;each short wingtip weighed 2.1 lbs.The swapping of wingtips was a taskrequiring only 20 minutes. Thus, thisreport actually covers the flying quali-ties and performance of two differentaircraft with distinct personalities.
All of the tests were performed in atotal of six flights during two days,November 9 and 10, 1996. All flightswere made with pilot and one crew
SPORT AVIATION 35
member/flight engineer, excepting thefinal flight which was performed solowith reduced fuel and long wingspan.
The data presented here are derivedfrom recordings using CAFE baro-graph #3 and pitot probe #2. TheLycoming power chart for the IO-540-K engine was used to derive the powersettings. The fuel flow readings weremade using the Vision Micro gauge onthe aircraft's instrument panel, and itwas known to be fairly accurate. Theintense testing schedule did not allowequipping the aircraft with the CAFEFoundation's fuel flow recording sys-tem for these tests and fuel flowreadings were not available during theshort wingspan test.
Jack Norris and Andy Bauer madea computation of the climb rate decre-ment caused by the barograph's wingdrag and showed it to impose a climbrate penalty of less than 1%.
s i .T
l\t:rn,Glasair IIISubjective Report
BY C. J. STEPHENS
Am I Lucky... Or What?
As test pilot for the CAFE founda-tion these past five years I have hadthe opportunity to fly many differentairplanes. This experience has enabledme to learn what I like and don't likeabout various features of aircraft de-signs. A lot of that preference is due topersonal taste but over time one learnshow his "ideal" airplane would be de-signed and equipped.
I was ecstatic when I learned thatthe next airplane to be tested by theCAFE foundation would be a GlasairIII. Not only had I heard many goodthings about the kit manufacturer andthe aircraft's performance, but I just36 FEBRUARY1997
C.J. Stephens collecting flight data in the short wing version.
The CAFE team: Above, l-r, back row, Otis Holt and C.J. Stephens (in cockpit), DavidHautamaki, Chuck Hautamaki, Ed Vetter; front row, Brien Seeley, Cris Hawkins, LarryFord, Steve Williams.
The last minute confirmation that the flight data collection is recording correctly.
happened to start building a GA lli onthe 4th of July this year. What an op-portunity it would be to do a completehandling and performance evaluationwhile in the early stages of buildingmy own. 1 hoped that the one presentedfor evaluation would be a good onethat was built close to the plans speci-fication.
This next part proves beyond adoubt that I am extremely lucky. Notonly was this Glasair III built withoutany builder design changes but thequali ty of construction was superb.From the first look at the plane to thelast, as Chuck Hautamaki flew it backto its home in Colorado, it was a feastfor the eyes; a work of art. On my ini-tial introduction to N3 13CH wordslike "perfection", and "masterpiece"kept running through my mind. It was
the smoothest, shiniest and best look-ing aircraft I had seen, inside and out.This one should become the benchmark of quality to which all buildersshould strive to attain.
TWO WINGSChuck's Glasair was built with both
the standard 23.3' wingspan and a setof longer wingtips which give a 27'span. The design of the longer wing tipmakes it possible to increase the fuelcapacity by putting 2.5 gallons of fuelin each tip, but Chuck chose to leavethem dry. Not having fuel in the tipsmakes changing them quite simple.The 16% increase in wing spanpromised to provide some interestingcomparisons in the flying qualities andperformance.
THE CHALLENGE ]
The test plan was to use the first dayfor preparation and the following twodays for actual flying. The plan in-cluded evaluat ing the hand l ingqualities with forward and aft center ofgravity in both long and short wingconfigurat ions, then ins ta l l ing theCAFE barographs and measuring a va-riety of performance data on each ofthe two wingspans. Considering thelimited time avai lable and the twowing lengths it was to be a busy andchallenging time for our small band ofvolunteers.
ARRIVAL
The plane landed at the CAFE testfacility in the long wing configurationcarrying the short wing tips in the bag-gage compartment.
The first operation after arrival wasto completely de-fuel the airplane toobtain an exact empty weight. Themain fuel tank is in the wing forwardof the spar, with an additional 5 gallonheader tank forward of the instrumentpanel. The exact weight and center ofgravity (CG) was determined using thein-floor electronic CAFE scales. Nor-mally we would establish a CG of 15%aft of the forward limit for the mostforward measurements, however, evenwith Otis Holt (right seat) carrying 20lbs of lead in his f l ight suit anklepocket and all of the baggage com-partment ballast in the most forwardlocation, we could only obtain a CG48% aft of the forward limit. Duringflight the CG normally migrates aftdue to the entire fuel supply being lo-cated forward of the spar.
The main tank is continuous fromtip to tip and connected in the center toact as one fuel tank. There are severalbaffling ribs throughout the tank withdrain/vent holes to allow the fuel totravel to the center pick-up point. Re-fuel ing is a slow process requiringfilling one side then the other and backagain to top off the first side. The fuelfills into the various cavities slowlyand care must be used to ensure a fullfuel load is obtained.
The design could also use a bettermethod of grounding the aircraft dur-ing refueling. It has always botheredme a little to connect a static groundwire to the main gear of a fiberglass
SPORT AVIATION 37
Estimated Cost:
Hours to build:
GLASAIR III, N313CH$ 57,000 total cost including materials, engine,
prop, interior, instruments and radios.2300 incl. 1400 airframe, 300 engine, 600 for
finish work.Completion date: June 1993
SPECIFICATIONS, LONG WINGSEmpty weight, with oil/gross wt.Payload, full fuelUseful loadENGINE:
PROPELLER:MakeMaterialDiameterProp extension, lengthProp ground clearance, full fuelSpinner diameter
Electrical systemFuel systemFuel typeFuel capacity, by CAFE scalesFuel unusableBraking systemFlight control systemHydraulic systemTire size, main/tailCABIN DIMENSIONS:
SeatsCabin entryWidth at hipsWidth at shouldersHeight, seat to headlinerBaggage capacity, rear cabinBaggage door sizeLift over height to baggage areaStep-up height to wing T.E.
13 inPrestolite: alternator, standard large starter
1 header tank in forward fuselage, 1 tank in wing100 or 100LL octane5.4+ 51.8 = 57.2 gal
2 ozCleveland discs
direct push-pull rods aileron+ elev, rud by cableElectro-hydraulic landing gear actuation5.00-5 (10 PR)/ Lamb 11.00x4.00-5 (8 PR)
gull wing doors each side41.5 in
39.75 in34.5 in100 lb
16x37 in opening above seatback51.5 in30.5 in
aerobatics with 23.3' span at 2120 lb: (rolls, loops, Immelman's,Cuban eights, but no intentional spins or snap maneuvers).
CENTER OF GRAVITY:Range, % MAC 10-28.5 %MACRange, in. from datum 79.65-87.88 inEmpty weight e.g., by CAFE 79.77 inFrom datum location 60 in fwd of cowl to firewall jointMain landing gear moment arm 95.75 inNosewheel moment arm 35.5 inFuel moment arms front/rear 65.75/81.35 inCrew moment arm 108.75 in
airplane expecting to get good enoughconductivity to prevent a spark at therefueling point.
During my initial conference withthe owner, 1 asked many questionsabout flying his plane and reviewedsome important numbers for use inflight. The information in the POHprovided by Stoddard Hamilton wasexcellent and provided the valuableinformation for the flight preparation.
PREFLIGHTChecking the oil and sumping the
fuel was easy with the ports providedin the natural places. These small in-spection holes, however, allowed littleaccess to other components for de-tailed preflight inspection of theengine compartment and other areasof interest.
Entry into the cockpit was accom-plished by stepping up onto the backof the wing. As can be seen in thephotos, the plane stands high on itsmain gear and requires a large step toget up onto the wing without steppingdirectly on the flap. This maneuver re-quires a little more than normal agilityand leg strength. Due to the high shineand waxed surface, standing on thewing without sliding off was difficultat times.
Note: Another Glasair III, built byLyle Powell, features a nifty little stepon the right side, below the entrance,which retracts by vacuum when theengine is started.
About the only way to enter thecockpit is to step on the seat, sit on theseat back and then slip into the seatedposition. The seat back is very sturdyand the procedure is easy after youhave done it the first time. The cockpitis roomy when compared to manyhomebuilts. 1 measured the instrumentpanel width to be 43" then walkedover to a nearby Mooney for compari-son and found it to be 41".
I was very pleased with the generalphilosophy of construction of this testairplane. It was clean, well organizedand simple. I think we all can learn al i t t le from that concept. The seatswere made of quality leather with fab-ric inserts and the head l iner wasUltrasuede. The interior was finishedin soft gray tones which seemed to en-hance the spacious, comfortablefeeling. The seat cushions were madeof a firm foam which proved to be
38 FEBRUARY 1997
Above: Chuck Hautamaki helped the CAFE team ready his aircraft for testing.
Above: Larry Ford, right, serves a hearty breakfast to the dawn flight test crew.
Owner Chuck Hautamaki, left, and CAFE test pilot C.J. Stephens
ABOUT THE OWNERChuck Hautamaki was born in
Hancock, Michigan and becameinterested in flying as a child as heobserved the adventures of theApollo Astromauts. He took fly-ing lessons while studyingaerospace engineering at Univer-sity of Minnesota. He laterswitched to mechanical engineer-ing, in which he is currentlyworking on his doctorate.
His first flight was in a PiperCherokee 140. He never ownedany aircraft except homebuilts. Hehas only missed Oshkosh once inthe last 16 years.
His first homebuilt was a 950lb, 160 hp, 230 mph Glasair tail-dragger which he completed inJune 1983. He enjoyed its roughfield capability.
He moved to Idaho a few yearsago to work with Dan Denney onthe Thunder Mustang project inBoise, using his skills in finite ele-ment analysis and graphitestructural design. Then he returnedto Minnesota, where many of hisfamily live, to complete his gradu-ate work. Meanwhile, his wife,Bonnie, who has a Masters of In-dustrial Engineering, found a goodposition working for HewlettPackard in Loveland, CO. Chuckmoved to Loveland just this year.
He has been married to Bonniefor 17 years and has two children,11 -year-old Andrea and 9-year-oldDavid.
"I flight plan for a 250 mph av-erage. I haven' t had a G meter,though I think I've pulled about3.5 G's on some high speedpasses." Chuck explains that DanDenney's Glasair III, with highcompression pistons, porting andelectronic ignition is quite a bitfaster than his.
Future plans: Chuck plans tokeep this aircraft and maintain it inits pristine condition. "I might lookat some numerical studies to see ifa different airfoil would benefitthis airplane. I've done a little bitof engineering work for StoddardHamilton in the past. If I designeda homebuilt I'd shoot for about230 mph cruise with 200 hp and 4seats."
SPORT AVIATION 39
The Glasair III sits tall and nearly level on its oleo strut landing gear.
very comfortable. The leg wells wereroomy enough to not be constrictingand the good leg support made longflights very relaxing.
The instrument panel was beautifuland well la id out for VFR flying.Across the top of the panel was a hori-zontal row of five Vision Micro engineinstruments. The second and third in-struments from the left were themanifold pressure and rpm. Since thosetwo instruments are referred to so fre-quently I feel they should stand outmore and not be buried in a row ofother similar instruments of lesser im-portance. It is a matter of balancingfunction and aesthetics. If the panelwere to be set up for IFR flying I feelthat the flight instruments would needto be moved up more to the line of vi-sion rather than having the engineinstruments along the top. The radio40 FEBRUARY 1997
stack was kept basic with one nicenav/comm and a transponder using ablind altitude encoder. All of the in-stalled electronic equipment workedflawlessly throughout the flight testing.
A simple tow bar was provided forground handling and worked very well.The plane was light enough that oneperson can easily move it about on theconcrete ramp.
TAXIINGThe Lycoming IO-540 sprang to life
and idled beautifully after a brief primeusing the electric fuel pump. A first im-pression is that this is a big engine (300hp) for such a small airplane and it givesoff a beefy sound. The stock exhaust sys-tem was installed using no muffler. Thenoise level inside the cockpit howeverseemed quite normal and comfortable.
Very little power was needed tostart the Glasair moving quickly downthe taxiway. Directional control is ac-complished using light braking withthe toe brakes. Brake pedals were onlyinstalled on the left side, although thefactory makes an optional set availablefor installation on the right side.
No cowl flaps were installed, how-ever the oil temperature and the CHTremained exactly at the desired read-ings on all flights even during thesustained high performance climbs.There was no heat cuff installed forcabin heating or defog operation. Evenwhile flying at altitudes of over 10,000'the cabin remained warm enough,probably due to engine heat and the oilcooler discharge air being directly infront of the cabin vent (right side) airintake. There was no outlet for any de-fog system, but a sl ight foggingproblem encountered on the groundwas quickly cured by opening an entrydoor momentarily.
The gull wing cockpit entry doorswere large, with a very simple and ef-fective pin locking mechanism and gasstruts to hold them open. With the en-gine running, the prop wash seemed toblow the doors around quite a bit. Forthat reason it seemed best to keep thedoor closed while taxing. On a windyday it would be even more importantto taxi with entry doors closed to pre-vent damage to the door hinges. Thefuselage sits level during ground oper-ations which provides an excellentfield of view.
The pre-takeoff procedures werewell sequenced and logical using thelaminated checklist provided by thebui lder . The flaps stay ful l up andlocked, or full down and locked but thetwo intermediate positions stay in posi-tion only if there is an air load againstthem. This is due to the way the lock-ing device works on the manual flaphandle located on the center console.The normal takeoff procedure is to usethe first notch of flaps. Therefore,when awaiting takeoff clearance theflaps wil l sometimes increase to ahigher setting. Prior to taking off itmay be necessary to reset the flaps totheir proper position. A more secureflap detent would be desirable to pre-clude possible takeoffs with the flapsin the wrong position.
The only provision for re-trimmingthe plane from the cockpit was theelectric pitch trim switch located on
the center console at about the beltloop height. Having it located theremade it awkward to operate. There wasno pitch trim indicator installed; how-ever, by looking back at the elevatorcounterbalance horn the trim could beeasily set prior to takeoff.
TAKE OFF
After a quick mental review of thePOH procedures and flight parameters itwas time to get airborne for a look at theflying qualities. I had been advised thatlift off should occur at about 90 mphIAS with the long wings. Chuck hadalso cautioned me about the possibilityof trapping the main landing gear out if Idelayed the gear retraction too long orclimbed too shallowly at first. With therapid acceleration and the relativelyslow gear retraction it is necessary tocontrol the airspeed until all of the land-ing gear indicators show full retraction.
Liftoff occurred abruptly upon rota-tion at 90 mph as expected. Gearretraction was normal and since thespeed was building rapidly, a slightlysteeper climb was used to maintain lessthan 120 mph until all three lights wereout. Although during the first flight thelanding gear retracted normally, on onesubsequent flight I did manage to trapthe right main in the unlocked position.This situation was further compoundedbecause the three red gear unlock lights
are partially hidden behind the throttleknob and not easily seen from the leftseat.
During the short-winged flights,takeoff occurred at 96 mph and the air-plane climbed in a more noticeablynose high pitch attitude. As indicatedby the tabulated data, the rate of climbsuffers during a climb when flyingwith the short wings.
STATIC LONGITUDINALSTABILITY
The airplane was trimmed to levelflight at Va (200 mph). Then, using theCAFE hand-held stick force gauge, Imeasured the pitch stick force at each10 mph increment of airspeed changeover the entire level flight speed enve-lope without re-trimming. This stickforce gradient gives an indication ofthe aircraft's tendency to return to thetrimmed airspeed. A flat stick forcegradient (low stick forces) makes theplane harder for a pilot to fly sincethere is low control force feedback.This becomes even more important inan airplane such as the Glasair III dueto the high airspeeds normally experi-enced where after even a brief periodof distraction the aircraft will quicklyend up considerably off airspeed andaltitude. The test was repeated at themost forward as well as at the most aftcenter of gravity locations that could
-10Pull
- -6
COk_O(O _2
ED
Push
Glasair III 27'span, fwd e.g.
Glasair III 27'span, aft e.g.
Glasair III 23.3'span, 55% e.g.
W10 @ 18% MAC
Cessna 152
80 100 120 140 160 180 200 220IAS, mph
Static longitudinal stabilitytrimmed hands-off at Va
be reasonably obtained. Measurementswere made flying with both long andshort wings (see graph).
My opinion is that all figures ob-tained show that the Glasair has anexcellent stick force gradient. There isa gradual and steady build-up of stickforce as the airspeed is changed awayfrom the trimmed speed. Even in themost aft configuration tested, the air-craft showed ample force. The graphshows the full results for comparison.
DYNAMIC LONGITUDINALSTABILITY 5
Short period damping characteris-tics were evaluated at 6,000' at 140,170 and 200 mph IAS in the forwardand aft CG configuration, using firstthe long and then the short wings. Bothstick-fixed and stick-free situationswere compared. The stick was held inneutral position during the stick-fixedand released during stick-free. The re-sults were virtually deadbeat during allevaluations. Excellent natural stability
Maneuvering stability, 117 mph IASgear and flaps down
o§- 5HI °
GUI, 27' span, fwde.g.GUI, 27' span, afte.g.
GUI, 23.3' span,mid e.g.
F.8L @ 27% MAC
T-18 @ 21% MAC
1 1.5 2 2.5Load In G's
Maneuvering stability, Va
SAMPLE C.G. CALCULATIONS, Glasair III N313CHAft Sample Item
Main GearNose Gear
PilotPassenger
Fuel, Front TankFuel, Wing Tank
Oil, IncludedBaggageTOTALS
Long WingGross WeightEmpty Weight
Empty Weight c.g.c.g. Range, Inchesc.g. Range, %MACe.g. In Inchesc.g. In % MAC
Weight1209.8436.7170.0170.0
2.7310.9
0.0
100.0
2400.0
25001646.4
79.7779.65-87.88
10-28.586.2
24.7%
Arm95.8
35.5
108.8
108.8
65.881.4
36.5
132.286.2
115833.6
15501.1
18487.5
18487.5177.7
25291.7
0.013220.0
206994.0
Forward Sample ItemMain GearNose Gear
PilotPassenger
Fuel, Front TankFuel, Wing Tank
Oil, IncludedBaggageTOTALS
Long WingGross WeightEmpty Weight
Empty Weight c.g.
Weight1209.8436.7170.0
0.032.3
310.9
0.0
0.0
2159.6
25001646.4
79.77
c.g. Range, Inches 79.65-87.88c.g. Range, % MAC i 10-28.5
c.g. In Inches | 82.0c.g. In % MAC 15.3%
Arm95.835.5
108.8108.865.881.4
36.5132.282.0
Moment115833.615501.118487.5
0.0
2120.425291.7
0.0
0.0
177234.2
certainly adds to the Glasair Ill's beauti-ful handling quality.
Dutch roll oscillations were excitedby synchronizing pitch/roll/yaw inputstogether. The damping was immediatewith no evidence of Dutch roll ten-dency when the test was performedusing both wing tip configurations.Yaw damping was positive althoughusually two overshoot cycles occurredafter rudder release.
MANEUVERINGSTABILITY '""'
Stick forces were measured as Gforces were increased with the aircrafttrimmed for level f l ight . The testswere conducted at 6,000' at Va (200mph) and in landing configuration at1.3Vs (117 Mmph). Measurementswere made at both the forward and aftCG positions. As would be expected,the aft CG. produced l ighter stickforces. The rate of stick force increasewas linear with ample stick force pre-sent at the maximum G evaluated. Thecontrol forces felt light enough forgood maneuvering yet had highenough feedback to assure accuratepitch control. ( See graph)
ROLL RATES
Roll rates were measured by timingthe bank change from the video record-ing made during each flight. The changewas measured from a 60 degree bankingturn in one direction to a 60 degree bankin the opposite direction in approxi-
ROLL RATE, degrees/second,includes input time
Speed.IASRV-6A
Tailwind W10Cessna 152
Glasair III, 23 'spanGlasair III, 27'span
Va8047
47
92 Rt./ 100 Lt75Rt./67Lt.
1.3 Vso3645
34
na52Rt./60Lt.
42 FEBRUARY 1997
Flight Dat
Glasair IIIN313CHairspeedscorrectedfor dragdue to thebarograph
mately level flight. Full stick throw wasused with no compensation made for thetime it takes to accelerate to the roll rate;therefore the actual sustained roll ratewould be in excess of that reported. Re-member, the fuel is carried in the wingsand we were performing the roll rateevaluations with a nearly full fuel loadand with both seats occupied. The com-parisons were accomplished with similarfuel loads on each flight. • , . • . - t • i. • ,
SPIRAL STABILITY
Several tests were performed to ex-plore the natural stability about the rollaxis. First the plane was trimmed tolevel 30 degree bank turns and re-leased. The times required for the planeto either increase, or decrease, the bank
by 15 degrees was measured. In allcases the airplane displayed a slight(approximately 1 degree/sec) tendencyto roll to the left. This seemed to becaused by an out-of-trim condition.The only cockpit trim available waspitch trim. I believe that, if the out-of-trim condition had been corrected, theplane would have remained in a con-tinuous rate turn, exhibiting neutralspiral stability. The test was performedat both 200 and 117 mph.
ROLL DUE TO YAW
A test was performed maintaininglevel flight at 130 and 200 mph IAS with1/2 rudder displacement, measuring thestick force required to hold the bank con-stant at a bank required to hold a constant
heading. The exhibited dihedral effectshould become more pronounced withslower airspeed or increased Angle ofAttack. See table below.
130 MPH 2.0 lbs stick force -i200 MPH 1.2 lbs stick forceI also checked to see if the wings
could be leveled from a 30 degree bankwith the use of the rudder alone. In bothdirections at 160 mph it was possible tolevel the wings although during the rightturn the recovery occurred more quickly,probably due to the torque of the engineand the slight out-of-rig condition.
STALLS
This Glasair III had small stall stripsinstalled on the leading edge of the wing
Flight Data
Glasair IIIN313CHrate of climbat full poweron astandardday at thealtitudesshown
near the root. During stall exploration Ifollowed the advice contained in the POHby ensuring that I had plenty of altitude(8000') before attempting stalls. I alsomentally reviewed the suggested spin re-covery technique should an unintentionalspin be encountered. Throughout the sixflights I had the opportunity to performmany stalls with both wing lengths andwith varying CG. locations. Every stall andrecovery appeared to be exactly the samewith the exception of one situation. The ex-ception occurred on one of the later flightswith the heavy barograph installed di-rectly in front of the airflow of the aileron.In this situation as the airspeed was re-duced, the aileron and rudder required tohold level flight increased so much that,just prior to stall, it became necessary touse full rudder and about 1/2 aileron.These abnormal inputs were caused by theinstalled CAFE test equipment. Even withthis large amount of control input the stalland recovery characteristics were quitesimilar to the other stalls.' All of the stalls observed reactedwith very little airframe buffet or no-ticeable sounds until about 1 mph priorto the stall. Then one very noticeableshudder would take place and the stallwould occur. At the stall the left wingwould always drop about 20 degreesand the nose would pitch down notice-ably but not uncomfortably. I feel theslight out-of-rig condition may havebeen the cause of the left wing drop. Inevery case the recovery was instanta-neous and positive following the slightforward repositioning of the stick. Alti-tude loss was minimal and no secondarystalls occurred during any recovery.Even with the asymmetry evident dur-ing the barographed flights therecoveries were very predictable andcomfortable. It should be noted that allstalls were preceded with a slow decel-eration of less that 1 mph per second.
Accelerated stalls were explored upto an airspeed of 110 mph with all of44 FEBRUARY 1997
PanelIAS92120140160180200
BarographCAS91.00121.00146.00166.50189.00209.00
N313CH Airspeed Calibration
the same characteristics being dis-played. A pronounced nose highattitude was required to maintain levelflight during approaches to the stall inthe short wing configuration.
LANDINGSI was very interested in evaluating
the approach and landings of the Gla-sair III since this high performanceairplane has on occasion given a fewpilots some difficulties. Field of viewletting down and entering the pattern isgood. Any blind spots can be elimi-nated through mild banking. The planeis noticeably faster than most airplanesin its class and planning the let down isa must or you will arrive at the airporteither too high or too fast.
The landing gear speed is 140 mphwhich seems adequate for most situa-tions The airplane is clean and doesnot want to lose speed easily until thegear and flaps are extended. This is an-other reason to plan the descentcarefully. Chuck explained that it wasrecommended to fully extend the flapsimmediately after the gear extensionon downwind. However, I felt that cre-ated a large drag change and neces-sitated a major power input to maintainlevel flight. My preference was to ex-tend only 1/3 flaps right after the gearextension, then extend the remainingflaps just prior to starting the base turn.
A pattern of 115 mph IAS works wellwith a target speed across the fence of100 mph. Accurate control of the air-speed is necessary. This airplane hashigh performance and requires good dis-cipline to fly it safely. On final it isextremely easy to hold the airspeed tothe exact number that is targeted for ap-proach and touch down. It has excellentpower response when acceleration isneeded and ample drag when decelera-tion is needed. With accurate control of
the power and pitch on final, the airplanewill touch down precisely where desired.
An important item is to not "pulloff the power and expect the airplaneto float to a landing. It shows its highspirited, high performance lineage andmust be flown completely throughoutthe landing. It is not a difficult proce-dure but if you are not used to landingthis way it will require some practice.
The cockpit sensation gives the feel-ing that the airspeed is quite high duringlanding. Normally during my experiencea landing roll of about 3,000' seemed tobe the standard although shorter rollscould be attained with heavier braking.The stiff landing gear leaves no doubtwhen the landing occurs.
Various types of descent profileswere explored and reported. (See table).It certainly was impressive to see ratesof descent near 4,000 fpm and true air-speeds in excess of 300 mph. J
LONG WING/SHORT WINGA burning question that seems to be
omnipresent is, "How do the differentwings lengths compare?" The most no-ticeable differences are the greaterclimb rate with the long wings and themore nose high attitude at slow speedswith the short wings. At altitudes above6,000', the long wing seems to win outas far as speed is concerned. As wouldbe expected, the roll rates are faster withthe short wings installed. The shortwing fits into a smaller hangar.
The landing speed with the shortwing is faster, requiring greater run-way length. Due to the Glasair Ill'shigh wing loading, the margin for piloterror during an engine-out approach tolanding would be extremely small. Thelonger wing configuration would im-prove the emergency landing problemby reducing the landing speed slightly.
Is it worth the effort to own bothwing lengths? Considering that the in-terchangeable wing tip construction isactually a minimal amount of effort it isprobably something that is worth doing.
CONCLUSIONSThe Glasair III is a fine airplane
with excellent flying qualities. It is notan airplane that is meant for the lowtime or inattentive pilot. The speedsand performance are outstanding. Thebuilder who keeps his airplane lightand simple is bound to be rewardedwith excellent performance.
