CAFE Foundation APR.pdf · Created Date: 5/13/2001 4:04:34 PM

RRVV--88AABY BRIEN SEELEY, OTIS HOLT AND THE CAFE BOARD

Sponsored and Funded by the Experimental Aircraft Association

AIRCRAFT PERFORMANCE REPORT

TRIAVIATHONTROPHY

CAFEFOUNDATION

PRESIDENTBrien Seeley

VICEPRESIDENTLarry Ford

TREASURERC.J. Stephens

SECRETARYCris Hawkins

TEST PILOTSC.J. Stephens

Otis Holt

DIRECTORSOtis Holt

Jack NorrisStephen Williams

Ed VetterScott NevinJo Dempsey

CHALLENGE TROPHY

he RV-8A is an all metal, tan-dem, low wing, low aspectratio monoplane like its pre-

decessor, the RV-4. Both are cre-ations of Van’s Aircraft in NorthPlains, Oregon. However, theRV-8A is a distinct new designwith substantially different fea-tures. It is intended to be a highperformance sport plane with amix of capabilities ranging frombasic positive G. aerobatics withnimble handling qualities to limit-ed cross country travel.

The prototype RV-8A present-ed to the CAFE Foundation forthis report is serial # 1 of thisdesign and it first flew on April 4,1998. The RV-8 is the taildragger

version of this aircraft while theRV-8A has tricycle landing gear.Thirty two RV-8’s have beencompleted as of this writing.

Among the innovations on theRV-8 are a new wheel pant designthat is reportedly of lower dragthan those used by Van’s Aircraftin the past. The Cessna AircraftCorporation has engaged DickVanGrunsven for help in theprocess of adopting a similarwheel pant design for its new182.

The RV-8A is offered in kitform with a Quick Build kitwhich the manufacturer claimsmay be assembled in as little as800 hours

The testing of this N58VAemcompassed 3 weeks inFebruary 1999 during which theCAFE Board members installed,tested and refined several newperformance flight testingupgrades. A new data acquisitionpackage that allows real time dis-play of angle of climb, glide ratio,Barograph derived rate of climband mpg was created for thesetests.

We wish to thank Ray Richterand Dick VanGrunsven for trans-porting the aircraft to the CAFEFoundation for testing and for theopportunity to keep the aircraftlong enough for a thorough eval-uation.

T

Photo: Larry Ford

SUBJECTIVEEVALUATION

RV-8A, N58VA

By

OTIS HOLT

I was really looking forward to DickVanGrunsven’s arrival in January to handover the keys to N58VA for this APR.Dicks reputation for honest, efficientdesigns precedes him, so it was a safe betthat the RV-8A would be predictable, freeof serious bad habits and a delight to fly.During the subsequent three weeks, withmore than twenty hours logged in a varietyof loading and flight configurations, theRV-8A would prove to meet and generallyexceed these expectations.

I was impressed by the casual ease withwhich Dick surrendered the only existingRV-8A before departing homeward in awaiting RV-4. I’d like to believe it wasbecause he’d been impressed by my pilot-ing skill during our brief checkride, but amore likely explanation is that he alreadypossessed such confidence in the aircraftitself that he had little cause for concern.Today homebuilders can choose from anumber of aircraft kits offering very highperformance, but the RV-8A stands apartfrom the others in this group with respectto the modest demands it places upon thepilot’s skill.

FIRST IMPRESSIONS

The “8” sits quite handsomely on tricy-cle gear, appearing to be larger than it real-ly is. The width of the large sliding

canopy increases for several inches abovethe level at which it joins the fuselage,contributing to an almost military pres-ence. The full engine cowling blendssmoothly into the fuselage, and theabsence of cowl cheeks sets the RV-8Aapart from Van’s earlier tandem and singleplace designs. A walk around the aircraftreveals elegant simplicity and balancedproportion from every viewing angle. Thisairplane is, indeed, very easy on the eyes.

Close examination of N58VA revealsworkmanship rarely seen on factory proto-types, and suggests that the staff at Van’sAircraft includes some very talentedbuilders. Nearly all metal seams on the air-frame are flawlessly butt-joined using pre-cisely installed flush fasteners, and displaynone of the distortion often seen alongrows of closely-spaced rivets. The fit andfinish of the canopy, cowl, and other chal-lenging parts are also superb. Constructionof N58VA employed the use of many com-ponents from the now fully matured RV-8kit inventory, including the very cleancowling, with a Nomex honeycomb core,and lightweight wing-tip fairings. Theupper surfaces of the wing-tip fairings,

IMPORTANT NOTICEEvery effort has been made to obtainthe most accurate information possi-ble. The data are presented as mea-sured and are subject to errors from avariety of sources. Any reproduction,sale, republication, or other use of thewhole or any part of this report with-out the 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.

ACKNOWLEDGEMENTS

This work was supported in part byFAA Research Grant Number 95-G-037. The CAFE Foundation grateful-ly acknowledges the assistance ofAnne Seeley, EAA Chapter 124, andthe Sonoma County Airport FAAControl Tower Staff.

SPONSORS

Experimental Aircraft AssociationFederal Aviation AdministrationAircraft Spruce & Specialty Co.Aerospace Welding Minneapolis, Inc.Fluke CorporationCessna Aircraft CorporationB & C Specialty CompanyEngineered Software “PowerCadd” and WildToolsBourns & Son SignsAeroLogic's Personal Simulation

Works SoftwareCardinal Electronics--makers of PropTachFlowscan flow transducersDreeseCode Software atww.dreesecode.com

COMPARATIVE AIRCRAFTFLIGHT EFFICIENCY, INC.The CAFE Foundation:

A Non Profit, All Volunteer, Tax-exemptEducational Foundation

4370 Raymonde WaySanta Rosa, CA. 95404.FAX 707.544.2734

Aircraft Test Facility, Santa Rosa Airport707/545-CAFE (hangar, message)America Online: [email protected]

CAFEHONORARY ALUMNI

Steve Barnard--RV-6AJim Clement--Wittman TailwindJim Lewis--Mustang IIKen Brock--Thorp T-18Larry Black--Falco F.8LChuck Hautamaki--Glasair IIIJeff Ackland--LegendJerry Sjostrand--ExpressRandy Schlitter--RANS S-7CStoddard Hamilton Aircraft, Inc. GlaStarFred Baron--Lancair 320Mark Beduhn--Cozy Mark IVDick VanGrunsven--RV-8A

Photo: Larry Ford

which form a flat-wrap conforming to theupper airfoil shape, do display some wavi-ness, which might be remedied by the rein-forcement of those areas with foam orNomex.

True to the designer’s philosophy,N58VA is equipped and finished with sim-plicity and minimal weight in mind, sothere are few items installed that could bedescribed as non-essential. Instrumentationis basic VFR, and the cabin interior ispainted instead of being upholstered.Builders would do well to follow Van’slead by limiting extras; the reward beingan aircraft that can be flown solo at justover seven pounds per horsepower, andthat is a recipe for excitement.

THE DESIGN

There is no magic to the means bywhich Dick extracts such great perfor-mance from his aircraft. His choice of athick, constant-chord, low aspect ratiowing takes maximum advantage of thehigh strength-to-weight potential of alu-minum construction and results in one ofthe more structurally efficient designsavailable today. Dick’s forte has been toidentify the ideal point of balance betweenthe structural advantages and aerodynamicpenalties associated with low aspect ratiowings to optimize performance of his air-craft for their intended missions. Couplingthis wing with a lightweight, aerodynami-cally clean fuselage and well-faired land-

ing gear results in an aircraft with a veryimpressive operating envelope.

The large body of experience and cus-tomer feedback Dick has accumulatedfrom the RV-4 clearly provides the founda-tion upon which the RV-8/8A wasdesigned. It is almost universally agreedthat the RV-4 is a true “pilot’s airplane”,but also that it presents a load managementchallenge when carrying large passengersor gear for travel, and that the rear seat canbe somewhat limited in space and creaturecomfort. These issues have been signifi-cantly improved with the RV-8A whileretaining good flying qualities.

In my opinion, the single most pro-found difference between the two aircraftis load management design philosophy,and this is worthy of some discussion. TheRV-8/8A is intentionally designed with avery forward empty center of gravity. Theseats are located as far forward and closetogether as practical, and a forward lug-gage compartment has been added, lendingto much broader loading options. The tablebelow includes a selection of sample load-ings we calculated for N58VA. Here c.g.position is given as a percent of the totalrange, so zero corresponds to the forwardlimit, and 100 to the aft limit.

The first example represents a typicalloading with two adults at gross weightwith full fuel. Use of luggage as forwardballast allows this flight to depart at a verycomfortable mid-range c.g., and even withfuel reduced to a 30 pound reserve, the c.g.ends up just 67% aft of the forward limit.Even the extreme condition described byexample B, with a heavy passenger, maxi-mum rear baggage, nothing in the frontcompartment, and fuel to gross weight iswithin published limits. In this case, asfuel is reduced to zero, the c.g. moves verynear the aft limit, as indicated by the nextexample.

As is always the case with aircraftdesign decisions, there is trade-off for theN58VA’s near immunity to aft loading.

Dick recommends that a 180 pound pilotcarry about 50 pounds of ballast in the aftcompartment for solo flight, putting thecenter of gravity about 25% aft of the for-ward limit. Lighter pilots would requireslightly more ballast. This is also the rangehe recommends for solo aerobatics, andour flight test experience would confirmthat it represents a good combination ofpositive stall recovery and comfortablestick force gradients during higher g-loadmaneuvers. Example D represents N58VAconfigured for solo flying with about twohours of fuel onboard. In addition to the.25 lb./hp power-loading penalty the bal-last represents in solo flight, the need forballast might be an inconvenience prior tothe solo continuation of a flight that had apassenger aboard previously. Perhaps alightweight, collapsible water containercould be carried to compensate for off-loading a passenger enroute.

It might be argued that the empty c.g. isa bit too far forward, but it should be notedthat the 200 hp/constant-speed installationis the most forward-c.g. configuration rec-

30

0

0

0

0

0

0

170

180

180

180

160

180

180

170

200

200

0

0

0

0

50

75

75

50

55

25

25

252

218

0

120

78

120

120

1799

1800

1592

1477

1420

1422

1384

61

87

97

25

22

25

25

9.00

9.00

-

7.38

7.10

7.90

7.69

A

B

C

D

E

F

G

FORWARD LUGGAGE

FRONT SEAT

REAR SEAT

REARLUGGAGE

FUELPOUNDS

TOTALWEIGHT

C.G. % AFTOF FWD

LIMIT

LBS/HP

SAMPLE LOADING (ESTIMATED): RV-8A 180 HP VARIANTS

SAMPLE LOADING: RV-8A N58VA 200 HP CONSTANT SPEED/1127 LBS. EMPTY

ABOUT THE DESIGNER

Richard VanGrunsven learned to fly in1955 and soloed at age 16. He rapidly ad-vanced through private, commercial, andinstructor levels, eventually acquiring amulti-engine ATP. His total flying time isaround 9000 hours which includes over5000 hours in homebuilts and over 1300hours in sailplanes.

Dick has been designing and buildingaircraft for over 35 years. The RV-3, hisfirst original design kitplane, entered themarket in 1973. The design objective ofthe RV-3, and all other RV models throughthe RV-8A, was that of a general purposesport aircraft with good handling qualitiesand a wide performance envelope. Addi-tional business objectives have beenaffordable kit pricing and kits which couldbe constructed with modest skills.

His designs have enjoyed great popu-larity, with 2158 examples of the RVdesigns completed. The RV-9 is anothernew, lower cost, 2 place design whose kitdevelopment is now in progress at Van’sAircraft.

Mr. VanGrunsven has a Bachelor ofScience Degree in General Engineering.He has conducted his own self-study train-ing in various aspects of aircraft design.The RV-8A, along with other recent Van’sAircraft kitplanes, is a product of their en-gineering team including an aeronauticalengineer and two other mechanical engi-neers. There are currently no plans toFAA certify the RV-8A.

ommended for the RV-8/8A. Example Frepresents N58VA with a 180-hpLycoming substituted. The useful load isincreased by about 30 pounds, and theneed for ballast is cut in half. Example Gis a rough calculation for an RV-8A with a180-hp Lycoming and a fixed-pitch metalpropeller. In the prior examples, the bat-tery is installed below the aft luggagecompartment floor, but in this case it isinstalled at the optional firewall location.Again, ballast is reduced by half, but take-off weight is nearly 100 pounds less than

for example D with the same pilot andfuel. As a result, the power loading is onlyslightly higher, while the wing loading ismuch less. I’m sure that this version wouldbe a pleasure to fly, and it would certainlyoffer great performance at much less cost.

ERGONOMICS ANDCOMFORT

The front seat of the RV-8A begins tofeel like home right away, and just climb-

ing aboard inspires a strong desire tolaunch skyward. The canopy’s convexsides provide a nearly straight-downview in any direction with a slight tiltof the head, and its large size permitsthe pilot to sit high up, yielding anexcellent view forward over the cowl.All switches and controlsfall readily to hand andseparation of the rudderpedals is just right,adding to a sense of sta-bility. In flight, the pilot’ssense of “linkage” withthe aircraft is immediateand complete, due inlarge measure to a nearlyflawless control systemthat translates the pilot’sdesires into immediateaction with little con-scious effort.There are a few veryminor detractions. Theinstrument panel is just alittle too close for thoseof us with compromisedvisual accommodationand I often found myselfreferencing it through thereading portion of mybifocals. Also, a massiveroll bar and forward

canopy shroud combine to trace an arcmore than two inches wide located about afoot from the pilot’s eyes that occupies abit more of the field of view than would beideal. This was most noticeable during for-mation flying, causing me to alternatelylean forward and back to keep the leadplane in clear view. In spite of the roll bar,the pilot’s field of view both in flight andon the ground would have to be describedas excellent, contributing greatly to the joyand safety of flying the aircraft. Finally,both of these conditions as well as thepilot’s comfort level would be improved ifthe seat were tilted rearward a few moredegrees.

The pilot’s seat is fixed, but the entirerudder/brake pedal assembly slides foreand aft on tracks, and is easily adjustedthrough a full six inches of travel bypulling on a release cable while pushingon the pedals with your feet. Sitting heightis adjusted by adding or removing cush-ions. Tall pilots should have no trouble fit-ting in. Although the parallel rails carryingthe sliding canopy limit width at the pilot’sshoulders to about 24 inches, cabin widthjust below them and at the pilot’s elbowsmeasure a full 32 inches, and canopywidth in the vicinity of the pilot’s head isabout 26 inches. The overall feeling is ofspaciousness, with plenty of room fortasks like chart folding, and there is suffi-cient legroom to comfortably rest your feetflat on the floor aft of the rudder pedals.Speaking of charts, a few pockets forstowage of these and other items would benice to have to supplement the glove boxthat is built into the panel.

The large sliding canopy is a work ofart, and is blended into the fuselage by an

575961646570757580858590

100110115120130140150160170180190200210

215

?

56.9758.9259.9762.6163.3069.4075.0474.9780.2584.7984.2589.6599.74

109.34113.57118.07128.43139.17148.31158.97168.00175.91185.57200.46210.05

215.04

236.64

52.9853.6356.6658.0659.8464.7270.2669.4976.5280.3281.0286.5796.22

106.21110.91115.96126.56136.53145.79155.48164.43172.29182.43195.81204.90

209.96

230.94

full flapsfull flaps1/2 flaps

cleancleanclean

full flapscleanclean

full flapscleancleanclean

N58VA ASI calibration

Cabin Baro hassame pitot/staticas panel ASI

Wing Baro usesa calibrated, certifiedgimbaled pitot/static

PanelIAS,mph

CabinBaro

#1

CAS,Wing

Baro #3config.Van's RV-8A

Photo: Larry Ford

Photo: Larry Ford

CAFE Barograph designer Steve Williams,installing the data network cable in theRV-8A.

integral fiberglass skirt, which moves withit. At first, I was concerned by the fact thatthe canopy is secured in the closed posi-tion by a single over-center latch on theleft side. When I asked Dick about this heresponded that pressure recovery at therear portion of the canopy actually putssignificant forward pressure on it in flight.It would have been nice to have some typeof detent to hold the canopy open a fewinches for taxiing, and evidently a detent“bump” along the track is included in thekit version. The canopy is not designed forflight in the open or partially open posi-tion.

N58VA’s Spartan VFR instrumentationleaves room to spare on the 33” widepanel. A vernier-type control located in thelower left corner operates the very effec-tive elevator trim. Because it resembles athrottle control, I would recommenddefeating the function of the push buttonrelease to prevent it from being erroneous-ly rammed home in an urgent moment. Aneyeball valve above the trim controldirects ample ventilation supplied by asmall NACA vent on the left side of thefuselage. The glove box and cabin heatcontrol are located on the right side. Thecabin heater is quite effective but does notinclude a provision for de-fogging thewindscreen. I should think this importantfeature would be easy to add.

The throttle quadrant, with prop andmixture controls descending in size fromleft to right, is located within easy reachon the left cabin wall, but the pilot’s handis slightly crowded by a structural bulk-head just aft of its location. TheLeft/Right/Off fuel selector is just belowthe throttle quadrant. The 16 inch centercontrol column carries a push to talk and atoggle switch that operates the electricflaps, and has a range of travel of about 8

inches fore and aft and just under 12 inch-es laterally. A row of stout toggle switchesand a few breakers are located within easyreach on the right side of the cabin belowthe panel, and their operation quicklybecomes second nature.

The rear cockpit provides a very differ-ent environment than that of the RV-4.Gone is the prominent rollover protectionstructure that so dominates the rear-seatexperience in the RV-4. The passenger cansee forward over the pilot’s shoulders andhas a much better sense of participation. Inits place is a tubular structure, which sup-ports the front seat and serves well as apassenger’s handhold, but does not extendabove the pilot’s shoulders. This bar couldalso be a forehead bumper for the passen-ger during rapid deceleration, so somepadding would be in order. The bar alsoserves as the attach point for the front seatshoulder harness. Unfortunately, theattachment is well below the pilot’s shoul-ders and could contribute to spinal com-pression during an accident.

The passenger is provided with basiccontrols including stick, throttle and rud-der. The rudder pedals are actually 1 1/2”diameter steel buttons welded to the endsof simple push rods, a clever and light-

weight solution.The control column, which is removable,had scratched an arc in the paint on theback of the pilot’s seat, indicating that itwas limiting forward control travel slightlywhen installed. Shortening the column afew inches would eliminate this interfer-ence, with the added benefit of giving thepilot’s control a greater mechanical advan-tage than that of the passenger.

The passenger’s backrest parallels thesame 25-degree angle measured for thefront seat, but is perceived as being morereclined. This might be due to the sunkenfoot wells, which have a 23-inch spread.Although the fuselage tapers down some-what, the passenger still has more than 29inches of elbow room. CAFÉ FoundationSecretary Cris Hawkins, who is 6’-3” tall,served as flight engineer for several of thedata collection flights, and one day spentmore than five hours in the back seat. Crishad plenty of headroom and felt that therear cockpit was just large enough for him.He did indicate that a more reclined seatwith better thigh support would improvecomfort for long-range flights. I had twoopportunities to ride in the back seat withC.J. Stephens at the controls, and found itto be quite roomy and comfortable for my5’-10” frame during those shorter flights. Ifelt that contouring or narrowing the lowerportion of the pilot’s backrest would allowthe passenger to sit in a more natural posi-tion.

Ingress and egress is quite easy foreither seat for aircraft of this type. Anoptional step just aft of the wing makes iteasy to climb onto the anti-skid wing walkon the left side. From there it is simply amatter of stepping onto the seat or floorand lowering yourself into the seat. Theflaps should be placed in the full downposition prior to shutdown to protect themfrom being stepped on and to improveaccess to the step. The rear seat backrest isremoved or tilted forward to provideaccess to the spacious rear luggage com-partment, requiring that the seat be empty.As with most light aircraft available today,neither seat is equipped with any specialprovision for energy absorption during acrash landing, except for that which the

Propeller max. static RPM

Vmax, TAS, 690’ dens.alt., 1668 lb, 29.9”, 2741 rpm, 13.9 gph

T.O. dist., 0 mph headwind, 3 ° C, 125 ft MSL, 1789 lb/1420 lb

Liftoff speed, by Barograph, 1789 lb, CAS

Touchdown speed, Barograph, 1738 lb, CAS

Minimum sink rate, 1723 lb, 81.6 mph CAS, 87.6 mph TAS

Glide ratio, idle, 106.8 mph CAS, 115.3 mph TAS

Noise levels, full power climb/75% cruise

Peak CHT in climb, 90 kt, full power

Cowl exit air temp @ 339°F CHT, 61°F OAT

CAFE MEASURED PERFORMANCE, N58VA2720 RPM

191/220 kt/mph

390 ft/236 ft

53.2/61.3 kt/mph

50.9/58.6 kt/mph

907.7 fpm

9.5

103/99 dB

360° F

163° F

Photo: Larry Ford

The first data flight: foreground, left, Brien Seeley and Steve Williams startthe Barograph while pilot Otis Holt and engineer Ed Vetter wait on board.

fixed landing gear would provide as it col-lapsed.

Cabin noise levels in flight are quitehigh, as can be seen in the measured per-formance section. I found it helpful towear foam earplugs under the headset, butI think I’d budget for a pair of very highquality active noise canceling headsets if Iowned the aircraft.

GROUND OPERATIONS

Taxiing the RV-8A is a breeze, thanksto an almost unobstructed field of viewand the short wingspan. The free-swivel-

ing nose wheel permits taildragger-typeturns when one main-wheel brake islocked. Steering is by rudder and differen-tial braking, though in reality the brakesare rarely required. The rudder is effectivefor steering at very slow speeds, andresponds instantly to a slight burst ofpower, if needed, to initiate turns.

It is also easy for one person to movethe 1,125-pound RV-8A about on theground manually without the use of a tow-bar. The nose wheel has stops at about 60degrees to either side of neutral, but thereis enough anti-shimmy friction built intothe pivot to allow the aircraft to be pushedbackwards slowly and steered by pushingthe nose from side to side. Preflight isstraightforward, with everything excepttire pressure easy to access and check. Thewheel fairings are very clean aerodynami-cally, but are not provided with ports forfilling the tires. Some pilots might betempted to launch with marginally lowtires instead of removing and replacing thenine screws securing the forward portionof each wheel fairing.

TAKEOFF AND CLIMB

This is where the real fun begins, espe-cially when flying solo with a light fuelload. During one such flight on a coolmorning, intended to simulate a CAFETriaviathon run, my takeoff distance wasmeasured at 236’, and sustained climbrates in excess of 2,500 fpm were indicat-ed. If you refer back to the table of samplecg loadings, example E represents the con-

figuration for thatflight. One mightexpect an aircraftcapable of such per-formance to bequite a handful forthe pilot, but this isnot the case with theRV-8A. Mind you,things do happenquickly, and low-time pilots willrequire enoughhigh-performanceexperience to insurethat they can keepup with the aircraftduring takeoffs, go-arounds and touch-and goes. The briskclimb performanceoffered by the air-craft at relativelylow speeds actuallyenhances safety byproviding the pilotwith more optionsmore quickly shoulda power loss occurduring the climb-

out. The rudder, being sized to satisfy the

needs of the RV-8 taildragger, has an abun-dance of authority on the RV-8A. A modestamount of pressure on the right rudderserves to keep the nose on the centerlineduring the brief ground roll. The aircraftlevitates readily with a smooth rotationinitiated at 50 mph, with no tendency toover-control. One hundred mph producesexcellent climb rates with a good field ofview over the nose. All speeds given hereare panel indicated airspeed in mph unlessotherwise noted. Even at a nose-lowcruise-climb speed of 125 mph with powerset at 24.5 square, the indicated climb rateremained over 1300 fpm at a takeoffweight of 1600 pounds. Aileron input tocounter torque during high performanceclimbs is barely noticeable. The use offlaps is recommended for takeoffs at high-er weight or density altitude, but generallynot required when flying solo. Naturally,takeoff and climb performance is degradedsignificantly at higher takeoff weights, butthey remain impressive. Takeoffs at maxi-mum gross weight lead me to concludethat the published value of 1800 pounds isjust about right, as distinctly longer takeoffrolls are seen and a slight sense of slug-gishness begins to be felt at weights nearthat value.

STABILITY ANDCONTROL

It could be that Dick did employ somePhoto: Larry Ford

Climbs

#4--2/2/99

#3--2/2/99

#3--2/2/99

#3--2/2/99

#3--2/2/99

#3--2/2/99

#3--2/2/99

#5--2/11/99

Descents

#2--2/1/99

#2--2/1/99

#2--2/1/99

#2--2/1/99

#2--2/1/99

#2--2/1/99

#2--2/1/99

#6--2/12/99

#6--2/12/99

#2--2/1/99

#2--2/1/99

16:05:49

11:08:38

11:14:06

11:19:45

11:25:00

11:31:12

11:37:26

08:08:56

16:07:34

16:09:10

16:14:30

16:16:00

16:23:20

16:24:35

16:26:00

09:19:10

09:15:50

16:30:05

16:31:25

2552

1047

954

965

983

989

969

na

7687

5081

6950

5353

6255

5033

3841

4535

4704

5338

3933

2501.8-3501.9

465.0-2499.3

469.0-2512.7

481.9-2502.5

495.9-2491.8

492.2-2517.6

477.1-2515.1

3447.6-4447.6

8079.9-6924.7

5210.9-4154.4

7051.2-5815

5406.4-4734.2

6325-5327.6

5074.3-4347

3796.6-3256.8

4606.8-3562.9

4778.1-3449.4

5374.5-4284.9

3935.9-3160.3

1800

1799

1793

1788

1782

1776

1770

1415

1734

1734

1729

1729

1724

1723

1723

1747

1749

1720

1720

99.5

106.8

106.0

97.4

85.5

74.3

86.3

96.6

205.2

142.0

95.9

106.8

76.2

81.6

71.5

96.2

96.2

80.4

70.3

103.3

109.0

109.0

98.3

88.0

76.0

88.1

100.0

228.7

152.9

105.0

115.3

83.2

87.6

75.5

102.1

102.1

86.0

74.1

13.2

12.5

12.5

14.0

14.9

15.5

14.7

14.9

9.6

6.7

6.2

6.0

7.5

6.8

8.7

6.2

7.8

8.6

8.1

4.3

4.5

4.5

4.0

3.8

3.6

3.8

3.8

5.9

8.5

9.2

9.5

7.6

8.4

6.6

9.2

7.3

6.6

7.1

Rate of climb, fpm

2069.2

2179.6

2078.3

2090.3

1995.9

1787.1

1972.3

**2263.45

Rate of sink, fpm

3362.0

1567.0

1004.0

1059.0

956.5

907.7

1001.1

968.7

1227.0

1133.9

1061.4

Same airspace for all climbs on flt. #3

26.5", 2710 RPM, 13.5 gph, C.X.T.26.5", 2710 RPM, 13.5 gph, C.X.T.

27.8", 2720 RPM, 19.0 gph, C.X.T. 140°F27.8", 2720 RPM, 19.0 gph, C.X.T. 140°F






**Triaviathon, 1412 lb., solo**Triaviathon, 1412 lb., solo

C.X.T. = cowl exit air temp.C.X.T. = cowl exit air temp.

All descents at idle throttle, coarse pitchAll descents at idle throttle, coarse pitch

Vne descent, cleanVne descent, clean

Va descent, cleanVa descent, clean

cleanclean

Vy descent, best glide, cleanVy descent, best glide, clean

cleanclean

minimum sink, clean

clean

clean, idle, coarse pitch

clean, idle, fine pitch

full flaps, idle, coarse pitch

full flaps, idle, coarse pitch

Flight/DateFlight/Date Start timeStart time Presalt., ft.Presalt., ft. Densalt rangeDensalt rangeWeight,Weight,

lb lb

CAS,CAS,

mphmph

TAS,TAS,

mphmph

Angle,Angle,

deg. deg. ratio ratio fpmfpmRV-8A, N58VA, 1800 lb GW

kind of magic in the design of the controlsystem, because it is extraordinarily good.The feel is silky smooth and there is nodetectable control slop in any axis. Theaircraft embodies the rare combination ofan unhesitant willingness to obey thepilot’s wishes and a low pilot workloadduring cruising flight. Control harmonybetween the three axes is excellent, in thatnone stands out in relation to the others inthe pilot’s perception of magnitude ofmovement or force required. Input forcesare pleasantly light within a wide range ofany trim condition, yet generally increasesubstantially to give the pilot adequatefeedback when deviating by a largeamount from that trim point.

We flew N58VA to evaluate stabilityand control at multiple center of gravityloadings ranging between 15%-85% aft ofthe forward limit. Takeoff weight at themost forward c.g. was about 1550 pounds,and about 1700 at the most aft. With a verygenerous c.g. range of 8.2”, it is not sur-

prising that we observed substantial differ-ences in control force and authority at theextremes. It would be prudent for eachpilot to consciously and deliberatelyexplore the edges of the envelope andestablish their own comfort range. Thechief effects of very forward c.g. weobserved were markedly increased weighton the nose wheel, higher stick-force/Ggradients and diminished power-off eleva-tor authority at slow speeds. I would per-sonally tend to operate within the 15%-85% region to preserve slow-speed,power-off flair power at the forward endand reasonable stick force gradients nearthe stall toward the aft end of the range.

LONGITUDINALSTABILITY

Dynamic longitudinal stability wasexplored by inducing elevator doublets,and found to be deadbeat at all speeds test-ed both stick fixed and stick free. Thiscontributes to the aircraft’s secure, rocksolid feel during maneuvers and in cruis-ing flight.

Static longitudinal stability was mea-sured by trimming to Va (140 mph indicat-ed) and measuring stick force required tohold speeds in ten-mph increments from70-190 mph, while maintaining altitude byadjusting power. Note that for the forwardcg condition, the result was a very sub-stantial positive force gradient as speedvaries in either direction from the trimcondition. In the aft-cg test, however, areversal of the force gradient was encoun-tered as speed was reduced from 140 to 70mph indicated, with the maximum forceoccurring at about 110 mph. It is generallydesirable that some positive force gradientexists as speed deviates more and morefrom the trim point, and imperative that noactual force reversals occur. I would rec-ommend that pilots explore aft-cg stallswith some care to familiarize themselves

with stick force behavior in this region.We did not conduct tests with loadings fur-ther aft, but the trend would indicate thatthe gradient reversal observed wouldbecome more pronounced, and stick forceduring stalls at the full aft limit could benear zero when trimmed for a normalapproach. The forward luggage compart-ment makes it quite easy to ballast loadingwell forward of the aft limit by placingheavier items there.

DIRECTIONAL STABILITY

The RV-8A responded to rudder dou-blets with about 2 overshoots beforedamping rudder-free and about 1 over-shoots with the rudder fixed. This is wellwithin the acceptable range, given that itresulted in no discomfort or annoyingDutch-roll tendency. There was nodetectable dead- band or excessive break-out force when actuating the rudder. It isinteresting to note that the RV-8A has norudder centering springs or devicesinstalled, so the fixed vertical stabilizerprovides nearly all directional stability. Infact, the aircraft even lacks any type ofpedal-return springs. As a result, the cablesgo slack when there is no foot pressure onthe rudder pedals. Dick’s response, whenasked about this was “didn’t need ‘em”,and that seems to be the case.

ROLL DUE TO YAW

Roll due to yaw was tested by measur-ing the bank angle and opposing stick

Va

109 Rt /102 Lt

47

61 Rt./63 Lt.

52 Rt./50 Lt.

1 3 Vso

78 Rt /80 Lt **

34

50 Rt./53 Lt.

47 Rt./43 Lt.

RV-8A N58VA

Cessna 152

RANS S-7C

GlaStar

**full flaps 80 IAS

ROLL RATE, degrees/second, includesinput t ime

Ο

Ο

ΟΟ

ΟΟ

Ο

ΟΟ

ΟΟΟ

∇

∇∇

∇∇∇

∇∇

∇∇∇∇

∇

◊

◊

◊◊

BBBBBBBBB

BB

++

++

++

10

8

6

4

2

0

-2

-4

-6

70 90 110 130 150 170 190

Ele

vato

r S

tick

For

ce, l

bs.

Instrument panel IAS, mph

ΟRV-8A, fwd c.g.,140 IAS

∇RV-8A, aft c.g.,140 IAS

◊RV-8A, fwd c.g.,80 IAS

BW10 @ 18%MAC

+ Cessna 152

Trimmed to zero pounds withstick- free and flaps up at Va.RV-8A at 80 IAS with full flaps.

Pull(-)

Push(+)

Static longitudinal stabil i ty

Pho

to:

Brie

n S

eele

y

CAFE test pilotOtis Holt, lt., andDick VanGrunsven

force required to hold a constant headingwith the rudder deflected. At 1.5 Vs (93mph) in the cruise configuration, rightrudder required 2.5 pounds of opposingforce and a 20-degree bank angle, with 2.0pounds and 20 degrees required to opposeleft rudder. A stick force of 3.5 pounds wasneeded to counter a full rudder deflectionin either direction, with bank angles ofabout 30 degrees. These results indicatemodest but adequate dihedral effect. Fullrudder deflection also resulted in an appar-ent partial stall of the rudder in both direc-tions at this speed, as evidenced by astrong buffet in the control, but of coursethis would not be encountered during nor-mal operations.

The rudder has adequate but muchreduced authority to induce rolls when theflaps are down. In the landing configura-tion at 1.3Vs(78 mph), deflection to theleft requires ten degrees of opposing bankto maintain a constant heading, and full

BB

B

B

B

B

J

JJJ

J

J

J

H

H

H

HH

H

FF

F

FFF

160

170

180

190

200

210

14

15

16

17

18

19

20

21

22

23

24

25

26

27500

600

700

800

900

1000

5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5

Tru

e ai

rspe

ed, m

ph

Fuel flow, gallons per hour

B TAS 2600 RPM

J TAS 2300 RPM

H MPG 2600 RPM

F Range 2600 RPM

MPG 2300 RPM

Range 2300 RPM

CAFE Score 2300 RPM

RV-8A: 8000' density alt i tude, w.o.t..**Comparative aircraft f l ight eff iciency score

Mil

es

pe

r g

all

on

Ra

ng

e,

sta

tute

mil

es

CA

FE

Sco

re**

B

B

BBB

B

B

B

B

J

J

J

J

J

JJ

J

J H

H

H

H

H

HH

H

H

F

FF

FF

FFF

F

150

160

170

180

190

200

14

15

16

17

18

19

20

21

22

23

24

25

26

27500

600

700

800

900

1000

5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5

Tru

e ai

rspe

ed, m

ph

Fuel flow, gallons per hour

B TAS 2600 RPM

J TAS 2300 RPM

H MPG 2600 RPM

F Range 2600 RPM

MPG 2300 RPM

Range 2300 RPM

CAFE Score 2300 RPM

RV-8A: 12000' density alt i tude, w.o.t..**Comparative aircraft f l ight eff iciency score

Mil

es

pe

r g

all

on

Ra

ng

e,

sta

tute

mil

es

CA

FE

Sco

re**

The graphs below use a Power-Performance data plotting technique developed by KlausSavier. The peak CAFE score occurs at the fuel flow and cruise velocity, V, which opti-mize the trade-off between speed and MPG and is typically lean of peak EGT. The rela-tive CAFE scores shown here, scaled to fit the graph’s Y axis, are based on the computa-tion (V1.3 x MPG), which is part of the CAFE Challenge formula.

Maneuvering stabil i tyNote: At 3.0 g's, fwd c.g.showed readings > 30 lb.

Ο

Ο

Ο

∆

∆

∇

∇

∇

∇

∇

F

F

F

Χ

B

B

B+

Ο∆

∆∇

++

0

5

10

15

20

25

30

1 1.5 2 2.5 3 3.5

Ele

vato

r S

tick

For

ce, l

bs.

Load in G's

Ο RV-8A, fwdc.g., 140 IAS

∆ RV-8A, fwdc.g., 180 IAS

∇ RV-8A, aftc.g., 140 IAS

FRV-8A, aftc.g., 80 IAS

Χ RV-8A, aftc.g., 180 IAS

BW10 @ 18%MAC

+ Cessna 152

rudder requires about 18 degrees. Onlythree degrees of bank was sufficient tooppose right rudder and about ten degreesfor full right rudder. Although the nosedrops when rudder is held in either direc-tion with the flaps down, multiple lighttaps on the rudder are able to alter andcontrol bank without the use of aileron.Strong positive rudder force gradientswere observed throughout the rudder’srange of travel at all speeds and configura-tions tested.

MANEUVERINGSTABILITY

The substantial stick force per G gradi-ents we measured for the RV-8A came assomething of a surprise. The pilot’s per-ception when maneuvering the aircraft isgenerally that forces required are fairlylight, and certainly that no undue effort isever required to obtain the desired result.At the same time, the sharp gradients wemeasured at forward c.g. insure that thepilot is getting excellent feedback from theaircraft when imposing structural loads,

making unintentional overloading unlikely.Naturally, the aft-c.g. force gradients areless, requiring more awareness on the partof the pilot, but even these are quite ade-quate.

ADVERSE YAW

It’s tempting to write “nothing toreport” here, because it comes close todescribing N58VA’s adverse yaw behavior.The design features Frise ailerons, whichare hinged such that the leading edge pro-jects below the wing when the trailing por-

#6, no cuffs, Baro #1

#4, with cuffs, Baro #3







































08:52:50

05:14:04

09:11:06

08:13:56

04:12:47

04:33:02

04:34:23

04:36:24

04:38:23

04:40:17

04:40:44

04:43:05

04:45:03

04:46:39

04:47:44

04:48:39

04:51:10

04:51:56

04:56:40

05:04:26

04:59:21

05:00:59

12:28:49

12:52:22

12:53:34

03:56:21

12:55:11

03:57:42

04:00:31

12:57:42

12:59:13

01:01:28

01:03:03

01:04:37

01:06:49

01:08:37

01:10:44

01:12:09

01:13:20

01:15:10

na

212.0

na

na

189.3

179.1

179.2

176.8

174.2

168.1

164.7

166.1

169.3

169.1

168.4

167.7

163.3

158.3

97.7

102.4

84.9

71.7

155.1

163.2

164.4

165.8

165.4

166.0

164.6

158.9

149.6

152.7

156.0

158.5

159.9

158.2

155.6

154.8

143.7

124.8

217.0

217.8

217.0

196.9

193.9

183.2

183.3

180.8

178.1

171.7

168.2

169.7

173.0

172.8

172.1

171.3

166.7

161.5

98.9

103.8

85.8

72.4

158.2

166.6

167.9

169.3

168.9

169.6

168.1

162.2

152.5

155.7

159.1

161.7

163.2

161.4

158.7

157.9

146.4

126.8

597.0

690.1

651.4

6086.2

5838.5

8019.7

8013.6

8025.4

7998.5

8026.3

8034.1

8030.1

8075.0

8039.6

8079.7

8106.3

8101.7

8050.4

7702.2

7678.1

7856.9

7915.4

12355.8

12046.9

12128.7

11814.0

12126.7

12113.4

12148.5

12020.7

11985.8

12221.2

12255.0

11913.7

11945.2

11915.8

11923.5

11905.2

11869.2

11808.7

0.983

0.980

0.981

0.834

0.840

0.786

0.786

0.785

0.786

0.785

0.785

0.785

0.784

0.785

0.784

0.784

0.784

0.785

0.793

0.794

0.790

0.788

0.685

0.692

0.690

0.697

0.690

0.691

0.690

0.693

0.694

0.688

0.688

0.695

0.694

0.695

0.695

0.695

0.696

0.698

218.9

220.0

219.1

215.7

211.6

206.7

206.8

204.0

200.9

193.8

189.8

191.4

195.3

195.0

194.3

193.6

188.4

182.3

111.1

116.4

96.6

81.5

191.1

200.3

202.0

202.8

203.3

204.0

202.4

194.8

183.1

187.7

191.9

194.0

195.8

193.6

190.4

189.3

175.4

151.8

30.2

29.9

29.7

w.o.t.

25.2

23.4

23.4

23.4

23.3

23.2

23.2

23.3

23.2

23.3

23.3

23.2

23.1

23.0

16.9

16.6

16.3

16.3

19.3

19.8

19.8

19.2

19.8

19.2

19.1

19.8

19.6

19.6

19.6

19.8

19.9

19.9

19.9

19.9

19.7

19.4

2752

2741

2780

na

2760

2589

2594

2597

2595

2583

2575

2295

2299

2295

2291

2292

2284

2285

1747

1769

1765

1749

2592

2583

2586

2587

2586

2588

2589

2580

2576

2301

2296

2289

2304

2301

2303

2298

2289

2286

15.0

13.9

14.4

na

12.8

12.1

11.7

10.6

9.7

9.2

8.5

11.2

10.7

10.3

9.3

8.5

8.0

7.2

5.1

5.1

5.0

4.9

13.2

11.1

10.5

10.1

9.8

9.5

9.3

8.6

7.8

10.9

10.4

9.6

9.1

8.3

7.7

7.3

6.7

6.0

14.6

15.8

15.2

na

16.5

17.1

17.7

19.2

20.7

21.1

22.3

17.1

18.3

18.9

20.9

22.8

23.5

25.3

21.8

22.8

19.3

16.6

14.5

18.0

19.2

20.1

20.7

21.5

21.8

22.7

23.5

17.2

18.5

20.2

21.5

23.3

24.7

25.9

26.2

25.3

1772

1739

1812

1412

1791

1774

1772

1770

1768

1766

1766

1763

1761

1759

1758

1758

1755

1755

1752

1748

1751

1750

1724

1697

1695

1744

1694

1743

1740

1692

1690

1688

1686

1685

1683

1681

1679

1678

1678

1676

568

616

592

na

643

665

688

749

806

820

869

665

711

737

813

886

916

986

848

889

752

647

563

702

749

781

807

836

847

882

914

670

718

786

838

908

962

1009

1019

985

16

18

17

na

17

17

18

19

20

20

20

16

17

18

20

21

21

22

10

11

7

5

13

18

19

20

21

22

22

21

21

16

17

19

21

22

23

24

22

17

2.6

2.8

2.7

na

3.0

3.2

3.3

3.7

4.0

4.2

4.6

3.5

3.6

3.8

4.2

4.6

4.9

5.4

7.6

7.6

7.8

7.9

2.9

3.5

3.7

3.9

4.0

4.1

4.2

4.5

5.0

3.6

3.7

4.1

4.3

4.7

5.1

5.3

5.8

6.5

Vmax s.l., no cuffs

Vmax, s.l., with cuffs

Vmax, s.l., no cuffs

Lightwt. Triav Vmax

Vmax @ 6000'

w.o.t., rich, 8000'

w.o.t., rich, 8000'

w.o.t., near peak

w.o.t., lean of peak

w.o.t., lean

power loss

w.o.t., rich, 8000'

w.o.t., rich, 8000'

w.o.t.

w.o.t., lean of peak

w.o.t., lean

w.o.t., leaner

rough engine

low power, near Vy

low power, near Vy

low power, near Vx

max endurance

very rich, 2600 RPM

w.o.t., extra rich

w.o.t., 99.8 dBA

w.o.t., rich of peak

w.o.t., rich of peak

w.o.t., best power

w.o.t., near peak

w.o.t., lean

w.o.t., sl. rough engine

w.o.t., 2300, rich

w.o.t., less rich

w.o.t.

best power

near peak

lean of peak

best CAFE score

economy cruise

engine rough

RV-8A N58VA

New TAS computed

based on CAS and

density altitude and

compensated for

wing cuff drag

41.92 gallons fuel

for computing range

3 gallons VFR reserve

Measured wing cuff

drag penalty = 5.8 mph

at 212 mph CAS

Baro #3 = wing pitot

Baro #1 = stock pitot

Flight #1= 1/31/99

Flight #2= 2/1/99

Flight #3,4 = 2/2/99

Flight #5= 2/11/99

Flight #6= 2/12/99

Flight #7= 2/15/99

See IAS/CAS calib.

for Baro #1 corrections

**TAS^1.3 x MPG/1000

Flight #/drag/Bar#Flight #/drag/Bar# DADDAD

ClockClock

CAS, BaroCAS, Baro

#3#3

CAS, no CAS, no

cuffs,mphcuffs,mph

Densalt., ftDensalt., ft Dens.Dens.

ratioratio

New TAS, New TAS,

mphmph

M.P., in. Hg.M.P., in. Hg. RPMRPM GPHGPH MPGMPG W eight,W eight,

lb.lb.

Range,Range,

milesmiles

**CAFE**CAFE

scorescore

Endur.,Endur.,

hrs.hrs.

CommentCommentCruise

flight data

tion is deflected upward, thereby creatingdrag to counter adverse yaw. On the RV-8A these are almost perfectly “calibrated”,so the ball stays centered during mild turn-ing maneuvers with no rudder input at all.A mere touch of rudder is all that is neededto coordinate turns with more abruptaileron inputs. Abrupt inputs without rud-der result in a slight hesitation before thenose follows into the turn.

When I suggested to Dick that the RV-8A, in the hands of a good instructor,might actually be suitable for primaryflight training, he correctly pointed outthat its self-coordinating tendency wouldleave the student ill prepared for mostother aircraft. Conversely, old habits dodie hard, and I never did entirely overcomea tendency to use excessive rudder duringturns.

ROLL RATES

The brisk roll rates we measured for theRV-8A can be found in the table below, butthe quality of its roll behavior is really ofmore interest than the absolute rate. Veryeffective ailerons and the low inertia of thelightweight wing work in concert to pro-duce gratifyingly crisp and immediateresponse to control inputs, and the rollceases promptly when the stick is returnedto the neutral position. Point rolls shouldbe easy in this aircraft. Rapid ailerondeployments are light and fluid, with stickforce just sufficient to provide good feel,with no accompanying tendency for thenose to rise or drop. It should be noted thatthe roll rates in the table below are calcu-lated from the time required to roll from astabilized 60 degree bank to a 60 degreebank in the opposite direction includingtime for the control input and acceleration.The absolute rate once established in asustained roll would be higher. A fairlycasual full aileron roll entered at 160 mphindicated produced a rate of about 135degrees per second.

The only quirk encountered was duringvery abrupt full deflections of the aileronsat speeds near Va, which resulted in astrong buffet being transmitted backthrough the stick, and slightly reduced rollrates. This was evidently due to flow sepa-ration along the leading edge of the Friseaileron that had been deflected upward,and was easily avoided by applying theaileron input less abruptly. Dick is awareof this phenomenon, and said he wasexperimenting with different leading edgeprofiles in hopes of finding one that pre-served the adverse yaw behavior withoutthe separation. I’d guess that most pilotsflying the RV-8A are unlikely to deploythe ailerons in this manner.

SPIRAL STABILITY

You would not necessarily expect anaircraft so ever-willing to roll as the RV-8A to display neutral spiral stability, butthat is indeed the case. After being placedin a stable, coordinated turn with a 20-degree bank in either direction N58VAshowed no particular tendency to deviatefrom that position with the stick free nei-ther at Va clean nor at 1.3 Vs in the land-ing configuration. Although the RV-8Adoes require a modicum of continuousattention during cruising flight, it won’troll over into a death spiral just becausethe pilot’s attention was diverted by amoment of chart reading.

TRIM AUTHORITY

The aircraft is equipped with a bungee-type aileron trim actuated by a lever on thelower left side of the cabin. Although itexerts only mild authority, it is quite ade-quate for keeping the wings level so longas the fuel load is kept roughly in balanceby switching tanks every half-hour or so.

Elevator trim authority is excellent onthe RV-8A. When trim control was operat-ed through its full range of motion (tenturns of the vernier knob) while holdingthe airspeed at 140 mph, the stick force

RV-8A, N58VA, SPECIFICATIONSEmpty weight/gross weightPayload, full fuelUseful loadENGINE:

Engine make, modelEngine horsepowerEngine TBOEngine RPM, maximumMan. Pressure, maximumTurbine inlet, maximumCyl head temp., maximumOil pressure rangeOil temp., maximumFuel pressure range, pump inletWeight of prop/spinner/crankInduction systemInduction inlet areaExhaust systemOil capacity, type, coolerIgnition systemCooling systemCooling inlet areaCooling outlet area

PROPELLER:MakeMaterialDiameter/PitchProp extension, lengthProp ground clearance, full fuelSpinner diameter

Electrical systemStarterFuel systemFuel pumpFuel typeFuel capacity, by CAFE scalesFuel unusableFlight control systemBraking SystemTire size, mains/noseSeatsCabin entryWidth at hips, front/rearWidth at elbows, front/rearWidth at shoulders, front/rearHeight, seat front to canopyBaggage capacity, front/rearBaggage door size, front /rearBaggage lift over height, frt/rearBaggage capacity, front/rearStep-up height to wing step/T.E.

1127.2 lb/1800 lb421.3 lb672.8 lb

Lycoming IO-360-A1D6200 BHP

2000 hr2700 RPM

atmosphericna

475 ° F55 - 95 psi

245 ° F14-44 psi

naBendix RSA-5 AD1 fuel injection

28.75 in4 into 2 crossover

8 qt., 50 wt.Slick 4373

Downdraft, hot accesssory section54 sq in

44.6 sq in

Hartzell HC-C2YK-1BF/F7666A-4aluminum

72 in0

13 in13.25 in

12 V battery/35 amp mini-alternatorSkytech starter 12 v.

2 wing tanks - fuel injectionengine driven pump, elect. boost pump

100 LL41.92 gal

8 ozcenter stick -dual

Cleveland500 x 5 / 11x4:00 x 5

2sliding canopy

27/ 23 in32/ 29 in24/ 24 in

42.5 in14Lx34Wx15H/ 27Lx23Wx27H

13 x 19 / 21.5 x 23 in51 in / 21 in (above with walk)

50 / 75 lb17.5 / 26.5 in

ranged from a 21-pound pull at full for-ward trim to an 18-pound push at full afttrim. The only time we reached the trim’slimit of authority was during 80-mphpower-off approaches at very forward c.g.loadings

STALLS

One-G and mildly accelerated stallswere found to be benign in all configura-tions and loadings tested. Stall onset wasindicated by very mild airframe buffetingand stick-shake, which preceded the stall

FLIGHT TEST DETAILS

13 flights were made during the first 2weeks of February, 1999, all during dayVFR conditions. A Flowscan 201A fuelflow transducer was used for the gph de-terminations and was calibrated bymeasuring the weight of fuel burned oneach flight. A PropTach digital tachome-ter was mounted on the top of theinstrument panel. Performance dataflights were conducted with pilot andflight engineer aboard and flying qualitieswere evaluated with solo flights using ananalog G meter and Brooklyn Tool & Ma-chine Co., Inc. NJ hand-held stick forcegauge.

Cruise flight data was obtained withthe wingtip CAFE Barograph (#3)mounted on a wing cuff with a dummybarograph and cuff mounted on the oppo-site wing. These were correlated with thepanel airpseed indicator to produce theairspeed correction table shown here. Ourdata suggest that Vy is 105 mph CAS andVx is 80 mph CAS.

A temporary mixture control linkagewas fabricated and installed so as to allowmixture adjustment by the flight engineerin the rear seat. The flight test equipmentwas mounted in the forward baggagecompartment along with 2 large gel cellbatteries to power the recorders.

Cowl exit temp (C.X.T.) is a functionof the OAT & CHT and is a measure ofthe efficiency with which the cooling sys-tem removes heat from the hot engine.This can be expressed as the temp rise rel-ative to the hottest CHT observed duringclimb:

(163 - 61) / 339 = 0.30

Compare this to 0.25 for the Cozy Mark IV.The RV-8A, with its fixed cowl exit size, neverreached a CHT above 360°F and could proba-bly reduce cooling drag by use of a cowl flap.

The CAFE scales were used to deter-mine the moment/arm of the aircraft’sfuel. This was found to be 80.11” aft ofdatum rather than the 80.0” described inOwner’s Manual.

Cost of airframe materials, no engine or inst.Kit starts sold to dateNumber completedEst. hours to buildPrototype first flewNormal empty wt. per Owner’s ManualDesign gross weight, lb, Takeoff/LandingRecommended engine(s)Advice to builders:

WingspanWing chord @ root/tip Wing areaWing loadingPower loadingSpan loadingAirfoil, wingAirfoil, design lift coefficientAirfoil, thickness to chord ratioAspect ratioWing incidenceThrust line incidence, crankshaftWing dihedralWing taper ratio, tip/root,Wing twist or washoutWing sweepSteeringLanding gearHorizontal stab: span/areaHorizontal stab chord, root/tipElevator: total spanElevator chord: root/tipVertical stab: span/area incl. rudderVertical stab chord: averageRudder: average span/areaRudder chord, bottom/topAilerons: span/average chord, eachFlaps: span/chord, eachTotal lengthHeight, static with full fuelMinimum turning circleMain gear trackWheelbase, nosewheel to main gearAcceleration Limits per factory:

AIRSPEEDS PER OWNER’S MANUALNever exceed, VneManeuvering, VaBest angle of climb, VxBest rate of climb, VyStall, clean, 1800 lb GW, VsStall, dirty, 1800 lb, GW, VsoFlap Speed, extended, Vfe

DESIGNER’S INFORMATION

CAFE FOUNDATION DATA, N58VA, Serial #1

KIT SUPPLIERVan’s Aircraft, Inc.

PO BOX 160North Plains, OR 97133

503-647-5117

OWNER/BUILDER N58VA

Van’s Aircraft, Inc.

$15,255 Standard, $22,750 Quick Build1018

32 RV-8, 1 RV-8A1600-2000 Standard, 800-1000 Quick Build

19981030-1125 lb

1800 lbIO-360 A1D6 Lycoming

Basic positive G aerobatics approved, keep it lightand simple.

23 ft 58 in/ 58 at tip joint

111.2 sq ft16.2 lb/sq ft

9.0 lb/hp78.3 lb/ft

NACA 23000 seriesna

13.5%5.310.5 °

0 °3.5 °

58 in/ 58 in0 °0 °

Differential braking, castoring nosewheelFixed tricycle

105 in/ 13.71 sq ftna

100 in/ 8.8 sq ft15.5 in/ 10.5 in

57 in/ 13.45 sq ft34 in

54.5 in/ 5.96 sq ft10.5 in/ 21 in

54 in/ 13.25 in58 in/ 13.25 in

20 ft 11 in87.5 in

30 ft at wingtip extremes76 in61 in

+3.8 g at 1800 lb/ 6.0 g at 1550 lb

200/ 230 kts/mph123/ 142 kts/mph

69/ 80 kts/mph91/ 105 kts/mph55/ 63 kts/mph50/ 58 kts/mph

87/ 100 kts/mph

by about 1-2 mph, depending upon theconfiguration. There were no stall warningor angle of attack devices installed on theaircraft. Stall behavior was generally quitebenign, but low-time pilots should practicestalls at altitude in all configurations toenhance their ability to recognize stallonset. With the flaps fully extended, theaircraft displayed a tendency to fall off tothe left somewhat at the stall. Recovery inall cases occurred almost instantly uponrelease of back pressure on the stick, andresulted in the loss of no more than 100-200 feet of altitude. Clean 1-G stallsoccurred between 56-59 mph with fullflaps and 60-63 mph clean, dependingupon weight. CAFÉ calibrated stall speeds,which are lower due to installation/positionerror, can be found in the measured perfor-mance section. The slowest 1-G stall wemeasured, at a flying weight of about 1400pounds and using the Triaviathon rule of15” mp/1500 RPM, was 47.5 mph!

APPROACH AND LANDING

The excellent field of view, fixed land-ing gear, and benign handling all contributeto safety and a low pilot workload duringapproaches to land in the RV-8A. The air-craft decelerates and descends readilywhen power is reduced, so descents fromcruising altitude do not require a lot ofplanning. This ability, in combination withthe great climb performance, gives thepilot a sense of freedom of movement in allthree dimensions.

A speed of 100 mph works well in thepattern and also corresponds to Vfe.Electric flap actuation is one of the fewextras that Dick was willing to include, andI feel that it was an appropriate choice.With the flaps effortlessly activated by atoggle switch on the control column, thepilot can give full attention to flying a safepattern. As speed is reduced to 75-80 mphwith the flaps extended and the prop at finepitch, the sink rate rises quite dramatically,so considerable power is required to main-tain a standard approach angle. Everythinggoes to slow motion during a properly exe-cuted flair, with the resulting touchdownspeed being about that of a Cessna 150.

Dead-stick landings are worthy of somepractice due to the increased power-offsink rate, and are made easier by leavingthe prop in coarse pitch until the runway isassured. Extra speed is in order when prac-ticing power-of landings with very forwardc.g. loadings, as elevator authoritybecomes quite limited at speeds normallyused for landing. In normal operation, asmall amount of power carried into theflair restores ample elevator authority.When doing go-arounds or touch-and-goes,the pilot should be mentally prepared toprovide substantial forward pressure on thestick after power is applied and until theflaps are up and the elevator re-trimmedfor the climb-out. The aircraft has amplecontrol authority to negotiate crosswindlandings, and these require no special tech-nique or skill. The brakes are excellent and

control during the deceleration to a stop isvery positive.

CONCLUSIONS

As C.J. put it, the RV-8A is a dream air-plane for the well-prepared low-time pilot,and I agree wholeheartedly. At the sametime, its exhilarating performance andgreat handling qualities will never leavethe veteran pilot bored. Imagine severalcategories of homebuilts, one being thosewith intrinsic safety, another those featur-ing great value, another those promisinghigh performance, and finally the group ofthose with great handling qualities. TheRV-8A would be equally at home in all ofthem. The group of homebuilts for whichthat can be said is small indeed!

20' 1

1"

23' 0

"

#3/16:17:39

#3/16:20:54

#3/16:25:32

#5/08:17:53

clean

1/2 flaps

full flaps

full flaps

12.0/1852

12.9/1868

13.8/1975

14.9/1470

1788

1785

1782

1410

52.4/60.4

48.5/55.9

47.0/54.2

40.9/47.1

fw d c.g. at variousfw d c.g. at various

M.P. and RPM'sM.P. and RPM's

W ing Baro #3W ing Baro #3

gross w t. = 1800gross w t. = 1800

Flight/ClockFlight/Clock ModeMode MP/RPMMP/RPMW eight,W eight,

lb lb

CAS,CAS,

kt/m phkt/m ph

Stall speeds--

RV -8A

CAFE Foundation APR.pdf · Created Date: 5/13/2001 4:04:34 PM

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Transcript of CAFE Foundation APR.pdf · Created Date: 5/13/2001 4:04:34 PM