Build the Dornier Do-335 Park Flyer

Add this seldom-modeled aircraft to your hangar

The completed model is ready for flight. In the early part of 2020, I designed and built a 70-inch version of the Dornier Do 335 Pfeil. The model was featured in this magazine (see the "Sources" list for the link). The model flies well and has such distinctive lines that I wanted to design a more compact version. The park flyer model has a 34-inch wingspan and is constructed with mostly 3/32-inch balsa, with light plywood, basswood, and various other balsa thicknesses. The model features three options for landing gear: hand-launch/belly flopper, fixed/plug-in gear, or retracts. However, to save weight, metal-gear servos replace standard retract units. Despite the model’s smaller size, there are many detail options that a modeler can choose to add. The canopy is made from flat sheet, and there are four options from which to choose. There are also lightweight paper cockpit and wheel-well details included in the covering templates. The model can be covered with printed tissue. These templates are included, along with full-size plans. The construction/covering notes are free to download on www.ModelAviation.com. Manzano Laser Works offers an excellent short kit that will help get you building quickly, and Rabid Models offers an assortment of accessories for the Do 335, including a power pack, 3D-printed parts (spinners, wheels/hubs, and strut covers), and metal-gear servos, should the builder choose the retract option (Manzano Laser Works and Rabid Models information are available in "Sources"). I recommend that you decide which version of the landing gear options you intend to use before starting construction. Review the plans and construction/covering notes because there are some areas that require additional attention before the glue meets the wood. There are also a lot of helpful pictures in the RCGroups build thread, as well as flying videos and tips on my YouTube channel, Fun Scale Models (see "Sources"). With your hand- or laser-cut parts ready, let’s move on to the build!

At a Glance

Specifications

Wingspan: 34 inches Power System: 24-gram, 1,300 to 1,700 Kv outrunner motors ESC: 12 to 15 amps Propeller: 9 × 7 × 3 Servos: Four 3.7- to 5.5-gram, two 9-gram, and one 4.3 metal gear (for retracts) Battery: Two- or three-cell 800 to 900 mAh LiPos Airframe weight: 16 ounces (without the battery) Wing loading with battery: 11 ounces per sq. ft.

DOWNLOAD FREE PLANS HERE!

PURCHASE DORNIER 335 PARK FLYER PLANS: plans.modelaircraft.org/product/dornier-do-335-2/ Full Plans Tiled Versions Paper Tissue Plans & Extras (8.5"x11" pages for both Tiled and Full plans) 34in Do-335 Construction/Covering Notes Mark the location of the hinges. These are made from CA hinge sheets (or standard ones can be cut to fit). Rabid Models offers a neat tool to help cut the slots for the hinges and to shape the LEs and TEs. Keel stringers have been added and the F17 through F19 assembly is in place. The HMR is attached to these formers.

Construction

Start with the fuselage construction. It is built in left/right halves over a keel. The verticals are made from 3/32-inch balsa sheet and have cutouts for cross-grain stringers. Add those now. Set aside the verticals and rudders when they are finished. With waxed paper or film protecting the keel construction plans, pin V3 in place. Note the parts that have a left side and glue F17 to F19 to V3 using the markings on the formers to align with the F20 centerline. Add part HMR and set aside for now. Pin and glue K1 through K6, V1, and WSC in place over the keel construction plans. Add the 3/32-inch stringers (shown in gray) that connect the upper keel to the lower keel parts at each former location. With all of the vertical and cross-stringers in place, lightly sand the surface of the keel assembly. Glue the F17 through F19 assembly in place over the keel. Starting with F16, add the left-hand side formers on top of the vertical stringers at each former location. After all are added, set the wing saddle/center stringer assembly in place, wetting the bottom edges with window cleaner to allow them to bend easier. Glue when you are satisfied. Glue in the lower hatch rail before adding the 3/32-inch balsa stringers, noting the ones that are basswood. Remove the assembly from the board and sand the right side of the keel to ensure that it is level and smooth. Repeat the same process when adding the right-hand formers, noting the cross-former stringers according to the plans behind F5 through F7. Before adding the stringers, it’s best to set up the nose-gear mounting plate (NGMP). If you are building with retracts, review the F7 detail on how to mount the servo, bend the 1/16-inch wire strut, and orient the servo. (Note that the servo is mounted to the bottom of the NGMP with the "top/horn" of the servo facing the left side.) The right-hand stringers can be added at this time (except between F5 and F9 below the center stringer). Glue the eight F8Bs together, and then glue to the back of F8. Use Scotch Magic Tape to protect the inside edge of the F8Bs, the top of the lower hatch rail, and the front of F12. Glue the upper hatch rails F8A and F12B in place. Make the holes in the lower hatch rail by using the ones in the upper hatch rail as a guide. Add the 1/8 × 3/32-inch magnets, minding the polarity. Add the scrap stringers according to the plans. Bevel the bottom edges of F10B and glue in place. Sand the top/side edges to match the fuselage. Bevel the bottom of F9A and set the canopy alignment guide in place on top of the stringer between F8 and F9 to set the angle, and then glue F9A in place. This shows the keel and the progression of formers and stringers. The author recommends not adding the top three stringers between F10 and F12 until working on the hatch. Several stringers only go between F19 and F20. The strut is connected to the servo with standard EZ connectors. When the retract and NGMP are sorted, slide in place between F6 and F7 under the cross stringers. Glue in the plate later. Add the 1/16-inch basswood stringers between F8A and F9A using the markings on the formers. If you are building the flat-top canopy option, add the stringers with no "curve" between F9A and F10B. The curved-top version is closer to scale and requires the stringers to be curved by either using steam or window cleaner. After the canopy framing is dry, blend the hatch rails and F8Bs to contour the fuselage. Add 1/16-inch cross-grained balsa on top of the center stringer between F5 to F12. Sand the entire fuselage to smooth it and prepare for covering. Cut the hatch free. Glue the front of the cowling according to the plans and shape it. Add the motor mount. Note that the centerline is offset to the right when it is viewed from the front. This is to allow for the 2° of right thrust. A 1/32-inch shim (from plastic or plywood) is added behind the right side (when viewed from the front). The wing’s leading edge (LE) blanks can be prepared from medium 1/4-inch balsa using the templates on the plans or parts from the short kit. Cut the trailing edge (TE) from 3/32 × 3/8-inch medium balsa. Build the wing’s center section first, making sure that the W1As are 90° to the board. Add the W1Bs, WMP1Bs, and stringers. Note that the slots behind the spars are left open. Shape the top of the LE, but leave the bottom flat and set it aside for now. Begin the outer panel by pinning the outer LE blank over the plans (do not yet add the mid-LE blank), along with the 1/8-inch square stringer noted at the tip. Pin WOJ in place and add Scotch Magic Tape over it to help reduce the chance of gluing it to the wing. Glue TE3 to the TE and set it in place over the plans and WOJ. Set the T1 and T2 assembly in place over the 1/8-inch stringer, test-fit W9, and glue the assembly together. Review the plans for the wood type for both the bottom and top 3/32-inch stringers—some are balsa and some are basswood. Stringers 4 and 7 extend halfway into the center section. These will be glued to the back of the spars when joining the panels together. Use T-pins between the rear of stringer 8 and the front of T3. This will create a 1/32-inch gap for the hinge line. Slide RMP into W5 and W4, and then set all of the ribs except W1 in place over the plans. Glue the ribs to the stringers and the LEs and TEs. RMP can be glued in place as well. Use the dihedral guide to set the angle of W1. (Angle it outward toward the wingtip). Add the top stringers, noting those that are balsa versus basswood. Ensure that the stringers are angled into the notches in T2 at the wingtip. Add the two aileron LE parts on top of T3 and against the T-pins. Make the aileron ribs from 3/32-inch blanks that will be sanded to shape later. Shape the top of the LE. Lightly sand the overall top of the panel before removing it from the board, masking then shaping the bottom. Preshape the mid LE before gluing it in place. Add the paper tubing for the servo leads between W1 and W4. Test-fit the aileron servo (4.3 grams was used on the prototype) and add the horn and micro EZ connector before gluing to the servo plate. Shape the aileron rib blanks, along with the wingtips, before separating the aileron from the wing. In-fill between the top and bottom 8 stringer in the aileron bay with scrap 3/32-inch balsa. Mark the centerline and cut slots for three CA hinges according to the plans. Test-fit the hinges and add the aileron back in the wing, pinning in place. If adding retracts, remove stringers 5 and 6 between W4 and W5, and W3 and W1, on the bottom of the wing. The precut section of W2 can also be removed at this time (creating the wheel well). The top stringers are not removed. Use the templates on the plans to bend up the main landing gear struts from 1/16-inch wire and mount the wheel. Install two standard-size EZ connectors to the horn of a 9-gram metal-gear servo. Set the servo in place on the bottom of RMP. Adjust the servo location so that the rotation point is in the middle between W4 and W5, and the EZ connector holes are centered in the cutouts of W3 and W4. Note this location and mount the servo with basswood blocks. Test-fit the strut so that the wheel is centered in the well between W1 and W3 according to the plans. Trim the excess length at the top of the strut so that it is just inside W5. Test-rotate the servo, extending the gear. The top of the strut should extend beyond the top of the wing—do not trim this. Parts F17H and F18H are added to their respective formers before the right-side halves are added. These will aid in alignment with the horizontal stabilizers. Canopy frame parts are beveled to match their angles to the top hatch rail. The canopy alignment guide sits on the center cross stringer between F8 and F9. Place masking tape on top of the ribs behind the rear edge of the LE blank to protect them while shaping. A small block plane is used to rough-shape the top of the LE. Smooth it out with 150- to 220-grit sandpaper. LE templates can be used to finalize the shape. Note the aileron and servo detail. It is recommended to use a standard and a reverse-rotation servo, so a "reverser" will not be needed. The RMP-1 detail is made from 1/16-inch plywood or a wide popsicle stick and added to the top of the wing. The assembled model before the covering is applied.

The model will be a park flyer with a wingspan between 30 and 34 inches and similar in construction and covering to the other models in his park flyer series. Marc Stermer, from Rabid Models, will offer additional details for the model as applicable (3D-printed spinners, wheels, landing gear covers, etc.). Depending on the aircraft chosen by the readers, the model will feature either plug-in landing gear, retracts, or both. Manzano Laser Works will offer a short kit should a builder choose not to cut their own parts.

Choose Derek’s Next Construction Project!

Choose one model from the following list and email your choice to Jay Smith at [email protected]. The aircraft with the most votes will be selected on July 1, 2024.

• United States Chance Vought F4U-1/2 Corsair Bell P-39 Airacobra
• Great Britain Hawker Sea Fury Bolton Paul Defiat
• France Dewoitine D.520
• Japan Nakajima Ki-84 Hayate
• Germany Heinkel He 100
• Soviet Union Yakovlev Yak-3

Test-fit RMP-1 in place so that when the strut extends, the top will pass through the slot, and when it is fully extended, it will be locked in place by RMP-1. This will also help reduce any flexing fore and aft of the strut during takeoffs and landings. Adjust RMP-1 as needed for the best fit before gluing it in place. Add the 1/16-inch balsa sheer webs as shown on the plans. Repeat the same process for the other wing panel. Elevate each panel 1.25 inch at W7 when gluing it to the center section. Note that stringers 4 and 7 are glued to the back of the ribs. The horizontal stabilizer is made from 3/32-inch balsa sheet but also has cutouts for cross-grain stringers, such as the vertical stabilizer and hinge, according to the plans. Bend the U-shaped elevator connector from .047-inch wire and install it into the LE of E1. Cover the fuselage back to front, alternating sides. When it is dry, lightly mist it with water (be sure not to have any large droplets hit the tissue) and allow it to air dry. This will help remove any wrinkles in the tissue. Seal with Krylon Clear Spray. Start with a light coat, gradually building heavier over time. Three or four coats will help seal the tissue to finalize the shape. Note the aileron and servo detail. After the tissue on both the top and bottom is dry, seal it with Krylon Clear Spray. Make the WMP-1 assemblies and glue them in place. Trim away K6 between F6 and F9, as well as the precut sections on those formers. Test-fit the 4.3-gram metal-gear nose-gear servo and strut. Glue NGLP-1 and 2 in place and test-fit NGLP, but do not yet glue it. Check the nose-gear clearance, fit it into NGLP, and adjust as needed. Cut away the LE in the center section between the W1Bs (on the retract version only). Add the remaining stringers between F5 and F9 and add WMP-3. Test-fit the wing and adjust the saddle as needed to ensure that the fit is good and 90° to the vertical before mounting it with four screws. Test-fit the horizontal stabilizer and ensure each side has the same amount of dihedral. The model can be covered in lightweight film, but it really shines when covered in printed tissue. There are two different liveries available to download, including one of the full-scale aircraft that is currently on display in the Smithsonian Institution. If going the printed-tissue route, follow the instructions in the construction/covering notes. Prepare for the covering by lightly sanding the overall structure. Use the color guides in the templates to color-match paint samples at your local home improvement center. Paint the horizontal and vertical TEs, wheel wells, canopy frames, and the area around the hatch. Add the cardstock template to the bottom of the wing center section. The tissue is attached using a glue stick. I recommend the purple glue sticks that dry clear; you’ll need at least two. Start by covering the tail surfaces then the fuselage, beginning at the rear and moving forward, alternating sides. After the fuselage is covered, lightly mist it with water and allow it to air dry, shrinking the tissue. Start the wing by covering the aileron LE and bay, and then the bottom wingtips. Add the bottom panels, moving in toward the center. Cover the center panel over the cardstock last. Add the top wingtip panels next. Before adding the outer upper panels, be sure to remove the pins holding the ailerons in place. Set the wing over WOJ when covering this panel to ensure that the washout is retained. Add the other panels. Mist the top of the wing while still over WOJ to shrink the tissue. Cut the ailerons free and glue the overhang to the LE of the ailerons. Mount the wing to the fuselage and build and cover the belly pan. Add the cardstock wheel-well covers and gear doors as shown on the plans. Install the elevator and rudder servos according to the plans. Cut the tissue to accept the horizontal stabilizers and elevators before sliding them in place. Take time to ensure that the alignment is good and that there are equal amounts of dihedral before gluing them in place. Build the belly intake and cover it in sections. Glue the supercharger intakes together and shape them. I recommended painting them as well. Add the exhaust stacks and the cardstock exits in the rear fuselage. Dry-fit the belly pan parts in place before gluing. Add the extra 3/32- and 1/4-inch balsa to the bottom of the center LE. Rough-cut it to contour to the bottom of the fuselage. Add the scrap behind the LE that butts against the front of F10A and install the stringers. Protect the tissue on the wing and fuselage with tape and contour the scrap and bottom of the center LE. Paint the bare areas light blue. Cover the belly pan with the tissue templates, starting at the rear. Apply along the center stringer first and use a straightedge to slide down the formers and to attach the template edge to the bottom of the center section. Add the wheel-well cardstock details, trimming as needed, and add the NGWW-1 cardstock template. The nose gear bay also has detail. Based on the canopy option that you chose when building the hatch, decide whether you will use clear or faux glass. Follow the steps outlined in the construction/covering notes. Connect all of the servos to the control surfaces. I used 1/32-inch wire with micro connectors. The prototypes used 900 mAh battery packs, and the model can be powered on a 2S setup with a 1,700 Kv 24-gram brushless motor or on a 3S setup with a 1,300 Kv 24-gram motor. After the motor is installed, add the cardstock cowling flaps. They can be added as one piece or individually. With the model assembled and the propellers and spinners attached, test the balance of the model and adjust it as needed with the battery and receiver location to match the center of gravity range on the plans. The second prototype balanced with the battery located between F10 and F11. This allows the cockpit to be installed between F8 and F10. The cockpit is mostly made from cardstock; the templates are included with the downloads. Set the control throws as shown on the plans.

Flying

When flying the model for the first time, choose a day with light wind. Check the controls for proper direction before smoothly applying full power. The model will lift off within 20 to 30 feet. Retract the gear (if installed) and trim the model as needed. Once trimmed, the model is a smooth and stable flyer. Both the 2S and the 3S setups provide scalelike speeds, and basic aerobatics are possible. The real fun is doing low and smooth flybys. The flat-bottom wing and washout provide for a gentle-flying warbird. Landings are a breeze. Line it up on the runway and gradually bring back the power. The model will settle in, and a light flair is needed. While the Do 335 is a park flyer, it feels and flies like a larger model. It’s an enjoyable build and flies true.

Trim the gear door mounts on the struts to be flush with the wing. Glue the cardstock door and balsa detail to the strut, filling the gap as needed. Cover with the tissue template. Glue the F14 C and D parts together, sand them smooth, and round the LE before gluing it to F14 B. The author recommends sealing the wood and paint instead of covering this part with tissue. Glue F14 A through F17 A to the bottom of the fuselage. Add the stringers before covering and gluing the assembly in place. Each canopy template is printed on standard paper, and then cut to the outside box edges. Each of these panels is folded along the dashed line and glued together, creating one side with the framing and the other in gray. Cut out the "glass" panels, and then glue the entire template to 3mil to 4mil clear acrylic sheet. Trim along the outside of the canopy framing when dry. Attach the panels with canopy glue, starting with the top first, then the sides, and, finally, the front panel.
The cockpit and profile pilot are made from both standard and cardstock paper. Additional details can be found in the construction/covering notes. 3D-printed landing gear details are available from Rabid Models. A finishing video is available on the "Fun Scale Models" YouTube channel (see the link in "Sources").

SOURCES: