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BONANZA A36 

This .91-powered Beech executive craft is an exquisite example of Precision Scale at its best. A scratch bu ilder's project PAR EXCELLENCE.

By Bud CaddellPhotos by the author Flight shots by Gary Tatasiore

Yep! It's a Bonanza, even though it doesn't have that funny looking V-tail. However, it's a directdescendant of the original that's been in continuous production since 1947, The V-tail was originally acost and weight saving scheme—although it appeals to some, the V-tail is now outsold by straight-

tailed Bonanzas at a 3-to-l clip.It wasn't much of a dilemma forme to decide which one to build... the A36 is a stretchedversion and better suited forR/C than other Bonanzamodels.

The scale is a 2-5/8 "-to-the-foot. I kept scaling until it waslarge enough for a Webra .91 to

fit comfortably in the cowl,along with a Tatone .91manifold. The A36 has a nosegear that is as far forward as anose gear can be. The nosestrut also has a forward rakeso, even though this is a bigmodel, it did become a littlecrowded in the cowl area. Thenose gear mount is somewhat

unconventional, but it hasworked out very well. Ihappened to have somemagnesium angle stock fromwhich to fabricate it. I'm suresome tempered aluminumangle would work just as well,

I'm not going to give youglue-joint-by-glue joint run downof the construction. We've

covered everything pretty wellin the plans. However, there area few high points I'd like tocover.

Once the crutch is laid downand the bottom formers areglued in, do as much sheetingas you can before unpinning.Support the side sheeting offthe board halfway up the

crutch, so that you'll have somebalsa to glue to when you starton the top half. The foam usedin the cabin area is urethaneand polyester resin doesn'tattack it. Cut the cabin outlinefrom the foam, tack-gluebetween formers F-2A and F-6A. Shape, using the templatesfurnished in the plans. When to

the proper contour, apply threecoats of Johnson's paste wax tothe foam. Apply two layers of 8oz. fiberglass Cloth, letting thecloth overlap the balsa about aninch. Feather-edge the clothinto the balsa by applyingmasking tape over the edges ofthe wet cloth. When cured, thetape will peel off with no

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problems. Finish the job withmicro balloons and resin. Theentire fuselage is then coveredwith 2 oz. fiberglass cloth.Squeegee as much resin fromthe cloth as possible. Two orthree coats of Super-Poxyprimer, sanded between coats

with 320 wet or dry paper, willproduce a slick surface onwhich to paint.

The wing is of conventionalbuilt-up construction. Don't omitthe shear webbing between theribs. This is where much of thestrength comes from. Do asmuch work on the wing aspossible before joining thehalves, it's a big wing and can

be cumbersome to work on.The wing and tail-feathers arefinished in the same manner asthe fuselage.

The overlapped panel linesare two layers of masking tapelaid down along the line. Microballoons and resin are workedagainst the tape with a spatulaforming a fillet about 1/2" wide.

When cured, it's sanded downto the tape, and then the tape isremoved.

The Bonanza is finishedwith R-M acrylic lacquer. This isa very fine auto lacquer that isvery close to the gloss you getwith Super-Poxy. The full-size

Bonanza has a high-glossfinish, and I wanted the sameon mine. The results I usuallyget with epoxy paints haveranged all the way from great toawful. I'm careful to vacuum thesurface and run a tack rag overit but still I occasionally getspecks in it. A fellow clubmember told me about R-M. Itried it on the fuselage of a

Pattern bird, and it has held upvery well. My tests showed thatR-M is not nearly as brittle asother acrylic lacquers.

I used very little plasticizerin the paint and still got a filmthat I could lift off of a piece ofmasking tape without cracking.The great advantage ofLacquers is that, if you do get a

sag or run you can sand itdown, then spray thinner (withretarder in it) to restore thegloss. If you're not completelyhappy with the results you geton the final coat, it's a simplematter to sand it down with 600wet or dry and then spray

thinner and retarder over it. Ifyou're not as lazy as I am, youcan enhance the gloss withpolishing compound andautomotive wax.

The A-36 has .010vacuumed-formed styreneailerons, flaps, and elevatorskins. The surfaces are built inthe conventional manner, andthen grooves are routed in the

sheeting to accept the plasticskins. A word of caution is duehere. The same method wasused on my Baron (June '79SR/CM) with great results. TheBaron's all-white surfaces haveset out in the sun at contests forhours on end, with no distortionset out in the sun at contests forhours on end, with no distortion

This 2-5/8"-scale model is large eno ugh that its 161/2 pound weight isn't critical. Construct ion is all-balsa,

except fo r a unique foam/fiberglass st ructure in the cabin area. scale r/c modeler 57

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The author assembles his prideand joy, with help from a fewfriends. This shot gives a good feelfor the size of the Bonanza.

to the plastic. However, thecolor scheme I chose for the A-36 was principally white, withdark blue flaps and ailerons. Atan outdoor exhibit, the A-36was subjected to 90° heat forthree hours. There were definitesigns that the plastic overlaywas being distorted from theheat—only in the dark areas.The white was cool to thetouch, while the dark blue wasdefinitely hot. Therefore, if yourbird is going to be in the hot sunfor a while, I would advise goingwith all-balsa surfaces. I haveexperimented with a Dremeltool with router attachment, andbelieve that a very realisticsurface can be obtained withthis on an all-balsa surface.

The A-36 weighs  16.5 lbs.

dry, ready-to-fly. This works outto be a wing loading of about 30oz./sq. ft. If yours runs heavier,don't fret, because the Wing willprobably support 18-19 lbs.

without serious damage to theperformance designed for 20 lb.airplanes and, if for no otherreasons, you should strive tokeep the weight down so youwon't have to change the nylonbearings every 25-30 flights.

The elevators are set upwith full up trim on thetransmitter giving neutralelevator. You'll probably get

level flight with a little downtrim. I have found with this forcearrangement that you have asmoother transition from power-on/flaps-up, to power-off/flaps-down. This doesn't mean thatyou won't have to feed downtrim in, but it does mean thatyou won't get a violent pitch upwhen the flaps are coming

down. Full flap deflection is 30° just like full-size. If you haven'flown flaps before, for goodnesssake practice some landings a200 ft. The sink rate with flapsis entirely different. Set theengine up to give 3500 rpm a

high idle trim, then drop thegear and flaps at about 300 ftand fly by at about 200 ft.

Note how much backpressure is on the sick. Now

 just imagine that the runway isat 200 ft. Start a flare. Does themodel gain altitude with moreback pressure? If so, it's toofast. Does it start to mush anddo the ailerons get insensitive?

Then it's too slow. If the modeassumes a slightly nose highattitude while slowly losingheight-then it's just right! You'lhave to monkey around withengine idle trim to get it right

I prefer a 16-4½ prop. Itdoesn't give you s muchforward speed as a 14-6, but tgives you lots of revs for take-off and climb out without

lugging the engine, son of likethe pulling power of a car insecond gear. Do most of youexperience that dead stick land-ings are quite often smootherthan with the engine running? A16-4½ seems to give asmoother transition at the flarepoint than other props, on thisparticular airplane. In additionto the plans ($17.50, plus $1.50

postage), we're offering a set offour engraved metal plates thaare affixed to, the cowl andfuselage ($5.00 a set). Also, wehave the "Beechcraft" fininsignia at $2.00 a pair. Thesecan be ordered from: Cadell-Hollock, 1525 Badham Dr.Birmingham, AL 35216.

 A lot has been written latelyabout 1/5-scaIe. Although the

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 Automotive acryl ic lacquer was used to give the Bonanza aprototypical high gloss finish.

Bonanza is slightly over 1/5th it certainly falls in that generalcategory. I'm firmly convinced that, with the .90 size enginescurrently available, this is the way to go. The Bonanza almost fallsin the low-wing trainer category, it's really that forgiving. I attributethis to the size An interesting side benefit to this size model is that—now don't

laugh . . . they're quicker and easier to build. There are no little

parts to contend with. The Bonanza was completed in about fivemonths, from the time I started to draw the plans. I tried very hardto keep the number of pieces to a minimum consistent withadequate strength. Also a very accurate airplane is easier toachieve in this size. Why? It is easier to cut a more accurate 12"rib .than a 6" one, because the sawing and sanding process is thesame for either but, at 12" the mistakes made are only a fraction ofthose made to the probably one reason you see more poorperformers in the .40 sizes than you do in larger scales.

The windshield is formed by two pieces of 1x1" hardwoodstapled to a 10x17" .040 Butyrate plastic sheet. The plastic is

heated in 250° oven. Let it sagabout an inch, remove it, andstretch it over the windshieldarea. After you're satisfied youhave a good clear windshieldcut the windshield area out ofthe fiberglass fuselage andinstall the windshield from the

inside, leaving a 1/4" gluingedge all around. Ditto for alother windows.

Rivets are applied by filing a22-gauge disposablehypodermic syringe flat at thetip. Duro appliance repairenamel is put in the syringe andthe plunger is compressed with

 just enough pressure that theenamel slowly oozes out. Hold

the syringe as you would apencil and let the glob ofenamel just touch the surfaceProper speed is probably a rivetper second. The Bonanza hasat least three sizes of rivets1/4", 5/16" and 3/8". If you planto be as accurate as possible, itis highly advisable that youinspect an A-36 for the rivetpattern.

 As with most all-metaairplanes, the A-36 is coveredwith many different panels ofvarying thickness. The wingsfor example, appear to becovered with aluminum nomore than .030" thick. I knowyou've heard many times thatyou should block sand alsurfaces so that you won't havehigh and low spats. Not so with

the A-36. I purposely sandedthe entire airframe prior tocovering (with 2 oz. glass cloth)with hand-held 220 paper; thisgives slight depressions hereand there that pretty welsimulate the slightimperfections and sags in thecovering of the full-size plane.

The cowl is built up frompolyurethane foam that's spot

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cemented to the firewall. The cowl is sanded to shape, and thenbroken loose from the firewall. Put two heavy coats of Johnson'spaste wax over the foam, then lay it flat side down and pourPlaster of Paris all over it about 1/2" thick. When the plaster isdried, remove the foam and cure the plaster in a 300° oven forthree hours. Coat the inside of the plaster with a good releaseagent, and lay two thicknesses of 8 oz. glass cloth inside. Press itcarefully into all recesses and let it cure at least 24 hours. You'll

probably have to break the plaster to remove the cowl. Thismethod requires some surface finishing, but is much stronger andfaster than balsa.

You'll have the .best chance of success with that first flight ifyou pick a day when the field isn't crowded. You'll be able toconcentrate better on making sure everything that needs to bedone gets done. The Webra .91 has an abundance of power forthis model. Don't try to get the last rpm out of it. Keep on the richside, and you won't have problems. Mine tachs at 11,200 rpm. Iback it off to 10,500 before flying.

When you've done your ground check, set the elevator trim to

about 3° down elevator. With this setting you'll have to pull it off theground—much better than having it try to come off prematurely.You'll find it tracks just super on the ground. It's got a wide stanceand short legs. This gives a very solid "feel," and it shows up whenyou firewall it for that first takeoff. Let her build up more speed thanyou think necessary before applying back pressure. At altitude,you'll find you'll have to come back on the throttle for a realisticcruise.

I really appreciate the nicecomments about our Baronplans from across the countryWe hope you will enjoy theBonanza plans just as much. □ 

The cantilevered nose gear is notyour usual installation. Highlydetailed plans illustrate how it'sdone.

 

Method for doing the panel detailing and rivets are explained in the text. The Bonanza is loadedwith lots of intricate detail