Build the B-17F

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Full Plans: The B-17 Flying Fortress is probably among the most widely used heavy bombers of World War II. Development began on August 8, 1934, for the U.S. Army Air Corps, and it was introduced into service in 1938. During its time in service, the B-17 was used primarily in the European Theatre, and although it was only the third most produced airplane used in WW II, it dropped 268,800 tons of bombs—more bombs than any other aircraft in the war. Beginning as the Boeing Model 299, the B-17 went through a number of changes and improvements from the original B-17A, culminating with the G model. Changes included a larger vertical tail starting with the e-model, as well as increased armament and engine upgrades. The model was done as the B-17F Memphis Belle. The Memphis Belle is probably the best known B-17 of the war, and it was the second B-17 to complete 25 missions, beaten by only a week by the B-17 Hell’s Angels. Robert K. Morgan’s crew flew their 25 combat missions in the Memphis Belle with the 324th Bomb Squadron from November 7, 1942, through May 17, 1943, over Germany and France. Morgan’s crew also flew four additional missions over Germany and Belgium from February 4 to May 4, 1943, in B-17s other than the Memphis Belle. After completing its tour, the Memphis Belle was flown back to the US on June 8, 1943, by a crew selected by the 8th Air Force, led by Capt. Morgan and his original copilot, Capt. James A. Verinis, where they flew a 31-city war bond tour. On the 75th anniversary of Memphis Belle’s final combat mission, May 17, 2018, the fully restored Memphis Belle was unveiled at the National Museum of the United States Air Force in Dayton, Ohio, where it remains on permanent display. 03. The main landing gear struts and retraction links are bent from steel wire using the patterns on the plans. 04. The tail wheel strut, bent from steel wire, is set up with its bearing tube and control horn testfitted so that it will be ready to install when the fuselage is assembled. 05. The wingtips, stabilizer tips, and rudder outlines are formed over patterns made from artist’s foam board.

The Model

Having built several multiengine models throughout the years, I’ve found a 60-inch wingspan to be ideal. It’s a great size for transport and is large enough to fly on regular flying fields, as well as in larger parks. Because of its lightweight construction and light wing loading, the flying speeds are relatively low and the functional flaps make the landing speeds manageable in smaller venues. Construction is basically of balsa and light plywood. The fuselage is a "trussed box" filled out with formers and stringers. Bowed outlines are used for the stabilizer, wingtips, and rudder outlines for maximum strength and minimal weight. The one-piece wing and the tail section are "egg-cratestyle" construction, and the wing is removable for transport. Battery access is by way of the removable cockpit fairing held in place with a single dowel and a magnet. Power is provided by four Suppo 400-class outrunner motors and set up with counterrotating propellers, which makes taking off on a narrow runway easy. The five-channel control is set up using a 9-gram servo for the rudder and elevator and each flap and aileron. A single 2,200 mAh 3S LiPo battery provides power for flights of 8 to 10 minutes. As with any multiengine model, there’s a lot of building to do, so take your time and enjoy the journey. Your efforts will be rewarded with a great-flying model of one of the most iconic aircraft of WW II.

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06. The flaps are built-up over the plans on a sheet balsa base. Vertical and diagonal bracing stiffens the sheet to prevent flexing when deployed. 07. The fuselage is built around an internal-trussed frame. The side frames are built directly over the plans. 08. With the fuselage main frame finished, formers are glued in place on all four sides. 09. The completed stabilizer assembly is removed from the plans and the remaining center sheeting is added and sanded to shape. The elevators are completed and sanded to shape, and the hinges are cut in and dry-fitted in place to complete the horizontal stabilizer assembly.

Building the Memphis Belle

For old-school scratch builders, full-size patterns have been provided for all of the cut parts, with plastic parts available from Park Flyer Plastics. For those who are not so inclined, a laser-cut wood and plastic pack is available from Manzano Laser Works. Decals for the Memphis Belle or any custom scheme you might desire, are available from Callie Graphics.

Preliminary Subassemblies

Before assembly begins, make up the bowing patterns for the rudder outline and wing and stabilizer tips from 3/16 artist’s foam board. Laminate the outlines using the wood sizes shown. For more detailed information about making bowed outlines, visit the link in the "Sources" section. Bend the main landing gear struts, retraction links, tail wheel strut, and elevator joiner using the provided patterns. The wheel retainers can be built-up at this time as well.

Fuselage Assembly

Construction begins by building the two fuselage side frames over the side view framing plans using the parts numbers and wood sizes shown. The sides are then joined upside down over the top view drawing by adding the top and bottom balsa crosspieces cut using the provided patterns, former 4B and WHD. With all of the crosspieces in place, add the bottom diagonal bracing. Each brace should be carefully hand-fitted—if they’re too tight, it will build an unwanted twist in the frame. Remove the frame from the board and add the diagonal bracing at the top of the frame. The top, bottom, and side formers are added next. Cross-section drawings for several former stations are provided for reference. With all of the formers in place, glue RM in place at formers 8 through 14, followed by WS, SSL, and SSR. Fit the magnet in place in HR2 and glue it in place at former 6. Set up the servo mounts and add the elevator pushrod guide tube. The tube is supported at the aft servo rail with a PRSO, at the rear through the hole in former 11A, at stations 8 through 10 using a PRSO, and out through the slot in SSR. Build up the tail wheel assembly and fit it in place at former 11, followed by TWMb. Run in the tail wheel pull-pull cables using the provided routing diagram and tie them off at the control horn, and then run the rudder cables out through former 10. Align and glue the battery tray in place followed by both BT2s. Now the 3/32-inch square balsa stringers can be added to complete the basic fuselage frame. Build up the upper cockpit/battery hatch assembly and sand to shape. Fit the 1/8-inch dowel into former CP3. Fit and glue the magnet into HR1, and then glue it in place on former CP4. Fit the hatch onto the fuselage and sand to final shape.

Fin and Rudder Assembly

The rudder assembly is built on the fuselage frame. Cover RM with waxed paper, and then tape D1 in place on RM. Dry-fit D2, D3, and D10 through D12 together and fit in place on D1. Align D2 with D1 with the spar angle gauge and glue at all points of contact. 10. The completed vertical tail assembly is sanded to final shape and the hinges are cut in and dryfitted in place. 11. To finish framing the wing, blocks are located under the panels to ensure that the wing remains straight and true during the finishing phase of construction. 12. The landing gear struts are lashed to the mount plates with heavy-duty nylon thread, and then the bottom sheeting is added. With the sheeting in place, the retraction links are soldered in place on the main gear strut. 13. The nacelles are assembled in place on the wing by first blocking the wing level then using a machinist’s square to align the firewall in its vertical position. 14. The top sheeting is glued in place directly on the fuselage to ensure proper alignment. Fit and glue D7 through D9 in place, followed by the 1/8-inch square balsa leading edge (LE) cap. Fit and glue the bowed outline in place followed by the 1/8 × 1/4-inch fill block. Trim the outline flush with the fill block. Save the cut-off pieces; we’ll use them on the rudder. The diagonal bracing is cut from 1/16-inch square basswood and glued in on the center. Pin D4 face down on the board and align and glue RR1 and RR4 in place on D4 using the rib angle gauge for proper alignment. Fit and glue the 1/8 × 1/4-inch balsa top rib in place, followed by the bowed outline at the top of the rudder. Next, add the trailing edge (TE), followed by ribs R2, R3, and the D6s glued in place flush with the outside edges of the rudder. Remove the assembly from the board and glue D5 in place on D4, followed by the diagonal bracing. Remove the fin from the fuselage, sand the rudder and fin to shape, and then cut in and dry-fit the hinges and toothpick control horn in place. Tape the rudder assembly in place, pull the control cables through the fuselage, tie them off at the control horn, and mark the exact location of the plans where the cables exit the fuselage.

Horizontal Stabilizer Assembly

Pin C1 in place over the plans and place a shim under each end to keep the spar level. Fit the SR1 and SR2 ribs onto the elevator joiner and dry-fit the ribs in place on C1 and C2, followed by all of the remaining ribs. Make up balsa shims, place them on the plans as shown, and glue the tip bows in place, followed by the 1/8 × 1/4-inch balsa and SLE LEs. Align the ribs and glue them in place at each of the ribs. Fit and glue the 1/32-inch balsa top sheeting in place. Remove the assembly from the board, glue the bottom sheeting in place, and then sand to rough shape. To build the elevators, pin the C4 hinge spars in place on the board face down. Dry-fit ribs ER1 to ER5 in place perpendicular to C4. Glue the 1/16 × 1/8-inch balsa TEs in place at ER1 and ER5. Align and glue all of the ribs in place at C4 and the TE. Build up the C5/C6/C7 assemblies, align them with the hole in C4, and glue them in place on the center, followed by C9 flush with the bottom of C4 and ER1 on the right-hand elevator. Add the 1/16-inch square bass wood diagonal bracing glued in on the center. Align and glue the C3s in place and sand to shape. Finally, cut in and dry-fit the hinges at the locations shown.

Building the Wing

Begin by pinning the A1 and A2 spar assemblies in place over the assembly drawings. Align and glue A1A and A2A in place in their respective locations. Remove the spars from the board. If laser-cut parts are used, align and glue A1C and A2B in place at the outboard end of the spar assemblies then turn the A1 spar over and glue A2B in place. Cut the left- and right-hand wing plans from the drawing, tape them together at the centerline, and then dry-fit the R1 and R2 ribs in place on A1 and A2. Pin FSM and ASM in place over the plans, pin the spars in place, and glue at ASM and FSM. 15. The motors are mounted on the firewalls, the ESCs are inserted into the nacelles, and the wiring has been run through the wing. 16. The rudder and elevator servos are mounted in the fuselage, which can be accessed through the wing saddle. A pushrod controls the rudder, and pull-pull cables are used to control the rudder and tail wheel. 17. The tail section is dry-fitted into the fuselage to ensure a good fit when completed. 18. The tail gunner’s fairing is assembled and contoured to the aft fuselage section then test-fitted with the rudder in place. Align and glue the R3A doubler and R4A in place on R3 and R4, and then glue R8A and R12A in place on R8 and R12. Dry-fit all of the ribs in place along with A3 and A5 and glue at all points of contact. Slip the MGM main gear mount plates in place between the R3 and R4 ribs and glue in place. Laminate LE2 and LE2A together and glue in place, followed by the 3/32 × 1/4-inch TE. Fit and glue the tip bow in place centered on the LEs and flush with the board at the TE. Fit and glue the 1/16-inch square bass wood tip bracing in place on the center, followed by the 1/16-inch scrap balsa gussets at R12. Add ASM1, ASM2, and FSM1 to complete the assembly. Rock the wing assembly over to the left-hand side and build the other wing. Remove the wing assembly from the board and place a 1-9/16-inch block under each R10 rib location. Pin WBP over the plans then pin the wing assembly in place and glue at WBP. Fit and glue the WS2/WS2A sheeting in place at the outboard nacelles. Remove the wing from the board, lash the main gear struts in place with heavy-duty nylon thread, and harden the lashings with thin CA glue. Solder the retraction links in place at the location shown. Run a string through the main spar at the nacelle locations and out of the top of the outer nacelle sheeting to guide the ESC wiring through after the wing is completed. Add the WS1/WS1A sheeting at the inboard nacelle locations. The string should be pulled through the hole in WS1 before the sheeting is glued in place. Turn the wing over and glue the bottom nacelle sheeting in place.

Building the Flaps and Ailerons

Cut the flaps from 1/32-inch sheet balsa using the provided assembly drawing. Pin the flap over the plans. Cut a strip of 1/32-inch balsa, 1/8-inch wide, and glue it in place at the TE. Next, add the LE and internal bracing using the reference lines. Add F1L and F1R to complete the assemblies. Remove the flaps from the board and sand to shape, and then cut in and dry-fit the hinges and control horns. For the ailerons, sand a bevel at the bottom of A4 using the R8 rib drawing for reference. Align and glue AR1 and AR5 in place and pin the assembly to the board over the plans. Glue the TE in place then fit and glue the remaining ribs and A6 in place. Remove the assembly from the board, sand to shape, and then cut in and dry-fit the hinges.

Building the Nacelles

Inboard: To begin, pin N1 on the board face down then align N3 and N3A perpendicular to the board in both directions, followed by N2, N4, and N5, and glue in place. Draw a centerline on the sheeting top and bottom. Next, mark the LE 1-7/16-inches on each side of the centerline at both nacelle locations. Align and glue N6 and N6A in place with the centerline on the top sheeting at the rear and the marks on the LE at the front. Turn the wing over and glue N7 and N7A on the bottom in the same fashion. 19. With all of the major components finished and roughsanded, a dry-fit is done to ensure proper fit and alignment. 20. The main wheels are held in place with a single wheel collar on the inboard side to retain the wheel bushing assembly on the axle. 21. After the model is covered and the tail section is in place, paper fairings are glued in place to fill the gap on top of the horizontal stabilizer. 22. The model was covered with iron-on Mylar, and painted using Tamiya acrylic paint sprayed with a small detail paint gun. The camouflage was added using an airbrush. When the paint work was done, the decals were added, along with a bit of weathering. Outboard: To begin, pin N1 on the board face down, align N3 and N3A perpendicular to the board in both directions, followed by N2, N9, and N10, and glue in place. Draw a centerline on the sheeting top and bottom. Mark the LE 1-7/16-inches on each side of the centerline at both nacelle locations. Align and glue N11 and N11A in place with the centerline on the top sheeting at the rear and the marks on the LE at the front. Turn the wing over and glue N11 and N11A on the bottom in the same fashion.

Mounting the Nacelles

Place the wing on the board and block up the TE at the center so that the flat bottom of the airfoil is parallel with the board. Use weights on the main gear to hold the wing in place. Slip the nacelle in place, centered on the nacelle sheeting, with N2 aligned with the marks on N2 flush against the LE. N3 and N3A should be parallel with the board and N1 should be perpendicular to the board. Glue N2 to the LE and N9 in place on N11/N11A. Repeat on the other wing then lift the wing and glue N10 in place at the rear of N11/N11A. Now all of the 1/16 × 1/8-inch square balsa stringers can be fitted and glued in place. Cut the bottom fairing from file folder paper and glue it in place to complete the nacelle. The outboard nacelles are fitted and glued in place in the same fashion. Finally, fit and glue all of the 1/16 × 1/8-inch balsa stringers in place, followed by NS1 through NS4.

Mounting the Wing

Lay the wing in place in the saddle and drill the holes for the LE dowels. Glue the hold-down dowels in place, and then remount the wing. Drill the #19 holes and tap for the 10-32 wing bolts. Harden the threads with thin CA glue and re-tap to clean the threads. With the wing bolted in place, fit and glue the center section formers in place, followed by the 3/32-inch square balsa stringers and skin with file folder paper.

Mounting the Motors, ESCs, and Servos

Center the servo arms on the four wing servos and mount them onto their respective locations using silicone caulk. When dry, run the wiring up to the R1 rib. Solder an adequate length of wire to the battery leads on the ESCs and mount the motors on N1. Plug in the ESCs onto the motors and slip the ESCs through the slots in N1 using the strings in the wing halvessto guide the wiring through. Connect the inboard throttle leads with a Y-harness, the outboards with a Y-harness, and then connect both with another Y-harness. Bring the throttle, aileron, and flap leads out at R1 and secure with WG. Connect all four B+ and B- leads together and solder the battery connector in place with enough lead to bring the plug through the battery tray. Secure at R1 with a WG. Finally, run the motors to check for the proper direction of rotation.

Cover and Paint

The model can be covered with any of the available lightweight iron-on coverings, Polyspan, or even lightweight silkspan and dope. Before the covering is applied, fine-sand the model to remove any irregularities. I also like to block-sand each former, except formers 1 and 14, between the stringers to eliminate the bumps in the cover. Apply the covering according to the manufacturer’s instructions and paint as desired.

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23. The belly pan was built up and skinned using file folder paper, and then painted to match the gray underside. 24. The battery mounts under the cockpit cover and plugs into the single lead extending through the battery bay floor.

Final Assembly

Glue all of the flap, aileron, elevator, and rudder hinges in place. Remount the wing and using it for reference, glue the vertical and horizontal stabilizers in place and add former 12 at the location shown. Fabricate the upper stabilizer fairings from file folder paper and glue them in place. Hook up the rudder cables, and then run in the .025 steel wire elevator pushrod. Connect it to the servo arm with a Z-bend, and then make a Z-bend at the hinge line. With the elevator in the neutral position, glue the control horn in place. Make the aileron and flap pushrods from .032 steel wire and connect with a Z-bend at both ends. Cut the cowlings from the carrier sheet and also cut the plastic between the cowling flaps. Bend the flaps open then mount the cowlings using silicone caulk. Paint the turrets, glue them and the tail cone in place, and then add the graphics. After the paint work is done, remove the mask from the turrets and make the gun barrels from 1/8-inch black heat-shrink tubing and glue in place. The windows are made from silver vinyl, with the waist openings called out with black vinyl. Finally, fit and glue the tail fairing, remaining gun barrels, nose glazing, and astrodome in place. Mount the wheels using the wheel keepers shown with hubcaps made from sheet styrene. The deicer boots were cut from black vinyl and applied to the wing halves and tail, and the propellers are mounted on the motors to complete the model. The center of gravity (CG) was set at the location shown using the battery to the best advantage. The battery was secured with Velcro. The control throws are set up as follows:

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Flying Your First Mission

Before the first flight, double-check the propeller rotation, CG, and control throws to ensure that everything is moving in the right direction. Then, when it’s all good, it’s time to fly. The B-17 turned out to be a terrific flyer and it’s as stable and honest as any multiengine model that I’ve flown. The controls, set up as shown, were fine even at full rates, although low-rate elevator works well too. The ailerons are slightly soft, but the elevator was a little lively, so a bit of elevator exponential was dialed in to tame things down. The flaps required no down-trim at either the takeoff or landing settings and proved to be effective. With the wing loading in the 13-ounce-per-sq.-ft. range, it flies at a scalelike cruise speed at half throttle, and landing speeds are quite manageable. The only trim required for straight-and-level flight was a bit of down-elevator. The model was so well behaved with the flaps fully extended that the landings were done with full flaps. The B-17 insists upon three-point landings, flaps extended or not, so it’s flown slightly nose down with a bit of power. Just before touchdown, bring the nose up slightly and it will float in for a perfect three-point landing. In all, as multiengine models go, the B-17 is the easiest to fly of the eight four-engine models that I’ve flown. For someone wanting to have a go at multiengine warbirds, the B-17 would be a terrific place to start.

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