Tora, Tora, Tora! A Japanese A6M3 Zero you can build

Jan 06, 2014 3 Comments by

Featured as a construction article in the March 2014 issue of MAN, this A6M3 Model 22 “Zero” is a great sport scale electric powered warbird that’s easy to build and fly. Designed and built by Mark Rittinger the Zero construction article hit the highlights of the project, but here are all of the details and photos not included in the original article. This exclusive bonus material will help you build this excellent scale electric design classic fighter from WW2.

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The Imperial Japanese Navy’s Type “0″ fighter is probably the most recognized Japanese aircraft of World War II. Coming as a bit of a surprise the Americans at the dawn of the war, and widely used in the attack on Pearl Harbor, the “Zero” proved a formidable weapon early on.  After one was found crashed on Akutan Island, Alaska Territory (“Koga’s Zero”) and made flyable, tactics were explored for fighting this nimble little fighter.  In 1942, instructions from the US Informational Intelligence Summary were “Never attempt to dogfight a Zero. The Zero has superior maneuverability to all our present service type aircraft.” That’s quite a bit of instruction!

Years ago, my father started the Royal kit of the .19 sized Zero, but he passed away before finishing it. I remember as a kid seeing the framed up Zeke in the rafters, waiting to be finished. I’ve always liked the clean lines, and excellent force arrangement of the Zero, and so I sat down and drew out what you see here, a 1.25″=1′ model for electric power. Several considerations were made. Keeping the tail light, the nose strong, and construction simple were paramount.

Plans ZERO

Order your planes at: http://www.airagestore.com/japanses-a6m3-zero.html

 

I was not confident that a battery hatch would work well, or fit enough battery, so I designed a “quick release” latch setup for the entire wing to come off. It has worked out great, there are no hatch lines on the fuselage, and changing batteries take seconds.

If you fancy yourself a little bit of an aerial Samurai , a fan of radial-engine fighters, or just love an A6M Zero, then I suggest you build this little nimble fighter, she won’t disappoint you! The model is 100% accurate in outline, and she flies as well as she looks. With some creative modifications, it could be a M1, M2, M5 or even a Rufe!

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The wing is a foam core affair, sheeted or cap-stripped with balsa. Retracts are an option, but they were not used on mine for simplicity, weight, and due to rough grass field restrictions. The structure for them is drawn on the plans, however.

The plans have the wing core templates, as well as all measurements needed to cut the cores. Cut them with 1/8″ washout per tip. Also cut the dihedral in the root to spec. Decide if you will be building a hand-launched variant (lighter and simpler) or a retract/fixed gear variant( heavier, more complicated, but “cool”).

Once your cores are cut, remove the handhold area OR retract area, and make the pockets for the aileron servos. Use a 1/2″ diameter sharpened tube to bore holes through the cores from the center to the aileron pockets. Line the pockets and handholds with balsa. On my model, I sheeted the “D tube” leading edge portion, and a portion toward the trailing edge, and cap stripped in between to save weight. When finished, it’s hard to tell it’s not fully sheeted. Decide upon full sheeting or cap stripping , and sheet the wing appropriately with light 1/16 balsa. Taper the trailing edge so that the sheeting will come to 1/16″at the T.E. Add the leading edge balsa. The cap strips are 1/16 x 3/16.

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I did not use the ply spars as in the center section as shown on the plan and the wing has held up fine, but if you land hard or fly at Mach 2, you may want to use them on the hand-launch version. There is enough wing there on the retract version to stay together without dihedral braces if there are no handholds cut out. If you are using them, cut the wing vertically and make the braces from aircraft ply.

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Cut your wing tips from light block balsa, and attach them, then carve/sand to shape.

Cut the notch in the wing roots for the release tab , and join the two panels together with epoxy. Sand the center leading edge and trailing edge straight, then wrap the center joint with glass cloth and 30 min epoxy.

Wing Release Mechanism

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Build up the release for the wing from 1/8 aircraft ply (not lite ply), a hardwood block, a 1/4″ dowel (or better yet, carbon rod), spring,  ply “donut”, and some triangle stock. Cut through the top wing sheeting to the bottom wing sheeting and slide the release in so that it fits against the bottom wing sheet. DO NOT glue it in yet though.

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Cut the ailerons and excess balsa from the wing, and install the wood facings. Bevel aileron facings to allow at least 25 degrees of up/down travel.

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The wing went together quickly , didn’t it?

TAIL SURFACES

There are two ways to make the tail surfaces: solid balsa, or foam covered with sheeting. Since I had a very light, Contest quality 1/2″ sheet in my box, I used that for the stabilizer and elevator. Be sure to make a center line around the perimeter to ensure that you get a symmetrical airfoil. I carved it in no time with a small razor plane, then cut off the elevators and trim pieces at the trailing edge. Bevel the front of the elevator halves. Make a small notch in the stab to clear the Sig elevator joiner. For the fin, I used 1/2″ sheet foam, sanded to shape  sheeted with 1/32 contest balsa using 3M spray contact cement. My model has no need for rudder, so the fin/rudder are all one piece. If building a rudder, follow the cut line on the plan, and face the fin and rudder with balsa. Make sure the fin has a tab on the bottom that will go through the fuselage top and attach to the top of the stab.

FUSELAGE

The fuselage is built in two halves, a top and bottom, then joined. Begin building by placing the 1/4 square stringers on the top view. Laminate 1/16 balsa cross-grained and cut out the balsa formers. Cut the ply F1 and F4 parts from aircraft ply, not lite ply. Install all the F “bottom” parts onto the side stringers, then add the bottom rear stringer. Add the 1/8 balsa gussets against F1B and F4B. Be sure that F1B and F4B are at 90 degrees to your board, and that the wing will fit in between.

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Plank the fuselage bottom with tapered 1/8 balsa planks about 3/8 wide at the front. I plank with light balsa, beveled edges, applied wet, with medium CA on the formers and Titebond II on the plank edges. Wipe up excess glue so it sands nicely.

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When dry, remove from the board, and lay down new side stringers for the top half. Again, place all the formers on the side stringers, and add the top center stringer. Plank the top fuselage section as you did the bottom, leaving the area where the cockpit is open. The top front receives a 1″ block to carve to shape in front of the canopy. When the planking is done and dried, remove it from the board.

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Make an elevator (and possible a rudder) pushrod and install in the fuselage to the elevator joiner. It’s much easier now than after assembly!

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Glue the top half to the bottom half, making sure it is aligned nicely. The F1′s should match perfectly. Add the front top block and then the fun part, sand it all nice and smooth. Carefully mark the wing location on the fuselage sides, and cut the wing saddle out. Leave plenty of wood to fine tune the location, and draw sand the saddle to get a nice fit. Once you have a nice fit at zero degrees (and 90 degrees to F1), drill through F1B for the wing mount front dowel. Next, glue the 1/4 dowel into the wing. Using the plan as a reference, mark the location of the stab on the fuselage and cut out the slot for the stab to slide in. Work a little at a time until it is straight and nice fit is achieved.

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Fit the wing in the saddle, line it up, with the release fit in place. Through the cockpit opening, mark the release’s location. Pull the wing off, and glue the release in place on the wing with epoxy. This is why we didn’t sheet above the wing/cockpit area: access.

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If you intend on making the wing fillets, now it the time. Fit the wing to the fuselage. I used the top view to make the outline of the fillets from balsa, then added small formers and 1/16 contest balsa . Some guys use balsa, some foam, and still others use putty or even paper for fillets, so I have left that up to the builder. Location is shown on the plans.

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Now build up the motor mount box from 1/8 and 3/16 ply. Pay attention to how its drawn, as the firewall is “captured” for strength. Be sure it has 2 degrees down and 2 degrees right at the front so the prop will be centered .This is why the box is offset to the left. Add the triangle stock around the perimeter. I use blind nuts behind the firewall for the X mount.

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Mount the firewall box to the fuselage with epoxy. The 3S5000 pack I used fits right into the box and gets the weight pretty far forward.Add the light balsa tail block and sand to shape.

 

Now cut a slot in the top rear fuselage where the fin tab is, and fit the stab and fin to the fuselage. When all is in perfect alignment, glue the stab in first, then the fin to the fuse and stab. Use Model Magic filler and a tongue depressor for perfect fillets around the stab and fin. Add the misc. cowl attach points, balsa fill around firewall, elevator servo mount, battery mount and cockpit bottom.

COWL

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The cowl is all balsa, with hardwood attach points. Using 1″ thick light plank, cut the sides and top to shape. Add the 3/8 and triangle pieces, and carve to shape. Leave the rear portion that goes against the model fully square, do not hollow that part. Once shaped , take some wood out of the inside with a Dremel and sanding wheel. Leave about 1/2″ wall thickness.

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Cut out a spot on the top and bottom for hardwood blocks, and glue them in . Place the cowl on the model, and drill the hardwood for mounting screws. I used nylon, so it can break away if need be. Tap the mounting parts on the model with 6-32, and mount the cowl. I also mounted an E-Flite AT6 radial motor face in the cowl…looks nice! She’s looking good now, right?

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FINISHING

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I used doculam film on the wing, as it is cap stripped.  This is a light, clear, laminating film. On the fuselage/tailgroup I used Deluxe brand EZE-Kote, a waterbased finishing resin, and .7 ounce Sig fiberglass cloth. I’m really happy with the results on the EZE-Kote/cloth: it’s clean, sands nicely, no odor, and not sticky. It’s turned out to be durable as well. It is applied in 3 coats: a base coat, sanded, and glass cloth coat, sanded again, then a  finish coat, sanded. The great thing? It dries in 20 minutes!

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After a few light coats of auto high-build primer and a sanding with 400 wet, hinge all surfaces. I use Ohio Superstar CA hinges. Paint the cockpit area, add the pilot bust and canopy, and tape off.

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I sprayed the whole model with a light coat of Top Flite Lustrecoat white primer. It adheres well to doculam film. I then laid out all panel lines with a pencil. Using an airbrush, I put black down on all panel lines, about 1″ wide. Then I laid the Tamiya Acrylic paints on top. It lets a bit of the black through, for a weathered panel appearance that’s quite convincing in person.  I used about an ounce and half of IJN Black-Green on top (with a few drops of white to simulate fade), and the same in IJN Gray on the bottom. All markings are airbrushed . I then drew all the panel lines on with a soft pencil, and added paint chipping with Tamiya “Chrome-Silver” by brush. A light coat of semi-gloss Tamiya clear spray paint was applied overal. The cowl was shot with cheapo semi-gloss black spray can paint. The markings are those of Saburo Shindo, 582 Kokutai.

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Install the aileron servos onto 1/16 ply hatch covers, and hook up to the ailerons using 1/2A horns. Run the aileron wires through the wing with 10″ extensions. Install the receiver in the fuselage with hook and loop fastener. Secure the ESC to the right side of the motor box . Install a 12-10 APC prop on the Power 25 870 kV motor, and make sure it clears the cowl. Add the spinner, which I painted silver. Check for proper control throws as set up on the plan. Make sure motor rotation is correct. Check the CG with a battery installed. The plan is at 25%, a good starting point .

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My ship came in at 61 ozs with 3s5000 pack. CG was dead on, no weight needed. 430 watts with 12-10 APC put it right  at 40 A. The wing loading came out at 24 ounces / sq. ft., with about 113 w/lb….more than enough for a warbird.

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COMMITTING AVIATION

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When you get to the field, make sure all surface deflections are correct. Make sure motor spins proper direction, and be positive the CG is correct. Also perform a radio range check. While 2.4 GHz radios are very reliable, they are not foolproof, and you have a lot of work in this bird! Once it’ll pass the range check, install a fully charged battery.

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Start with about 5 clicks of up trim, and have a  buddy hand launch into the wind at about 15 degrees nose up attitude. She should get up on step quickly. Get some air under the Zero, and trim her out for straight and level flight. Perform a CG dive test, and try inverted flight to double check CG. She should use about 1/4 to 1/3 down stick to stay level.

Low speed: The Zero does well at lower speeds, as the washout really helps. With quick thumbs, you might be shocked at how nice it’ll handle when slowed down. It will not go to walking speeds, but then again ,few WWII fighters will!

High speed: This model LOVES to fly fast! The short nose and ample wing area for her size gives the Zero excellent handling at full bore. It’ll move along , nice and steady, with little deviation, and a very nice groove. While not a Pattern model, it does possess a nice “sit” at high speeds, and control response is immediate. I suggest low rates at high speed, as the ailerons are large and the tail is rather short coupled.

Aerobatics: As with the full scale, I have found the Zero to be quite aerobatic, even without benefit of rudder. Since my model is hand-launched and I wanted to chase around flying buddy Mike Brinker’s 48″ “Jug”, I figured rudder was a waste. The model does large loops, nice rolls, smooth inverted, great point rolls, really nice ,big Cubans and vertical 8′s. Tweaking the CG may result in a few more moves…but for now he better watch his 6!

Landing: Practice a “landing” at altitude to gauge sink rate. Once on final the A6M will remain pretty steady with a smooth sink. The washout will help on approach, when you flare for the landing. My maiden ended with a hearty bounce, and no damage, so you might consider highrate on elevator just to be sure you don’t “run out” of elevator. Always leave enough power in the pack for a “wave-off” should you need it!

As always, I hope you enjoy your handcrafted A6M3 “Zero” as much as I enjoy mine. If you have any questions, or would like to order a canopy, contact me via email at: mrittinger70@hotmail.com

 

 

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3 Responses to “Tora, Tora, Tora! A Japanese A6M3 Zero you can build”

  1. davidchoate says:

    thats awesome. I got a Guillows 28″ WS, and Im ganna use alot of what I saw in Ur build.

  2. David Wayne Choate says:

    awesome. I’m converting a Guillows 28′ WS Zero, And I’m Gona use alot from Ur Build, but I’m just gonna use Rudder, and Elevator. Where’d U get the canopy?

  3. Azouz Bachouche says:

    Great work for a scale model like the Zero.

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