Top Flite B-25J Mitchell Project

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Page 17

         The waist gunner assemblies were now prepared for installation. The plastic windscreens were pre drilled with a 1/6” drill as seen below

       The gunner assemblies mounted easily using six #0 x 1/4 screws. Being able to remove these later may prove to be useful for repairs or modification to the fuselage.

       The ADF “football” antenna magnets were installed at this time as well . I used 5 minute epoxy to glue these in. Make sure these magnets are polarized correctly to attract and not repel the ADF antenna.

       I chose to install a Futaba R5114DPS receiver to control the B-25. The flexibility of being able to use 14 channels will be very useful and in this case almost necessary. In fact all 14 channels will be used on this model.

       Here is a photo of the final radio installation. All of the servo leads were numbered and correspond to a channel in the receiver. The 9 volt battery below the receiver is for the landing lights and can run them for several hours continuously.

       The cockpit cover was prepared by gluing the seats in place with medium CA glue. It is important to remove the green paint from the bottom of the seats and roughen the wood’s surface slightly to let the CA bite into the wood.

       The control yokes were glued into the cockpit at this time as well. Notice the silver paint accent on the handles.

       The fuselage was complete with the exception of adding the receiver battery and glow driver battery. These will be added once the Center of Gravity or CG is measured and the batteries can be place in the fuse to help with the balance.

       The addition of the gun blisters on the sides of the fuse prevented the foam cradle from being placed far enough forward so I modified it to clear the blisters.

       The B-25 was really taking shape now and in my honest opinion I was quite excited to fly this beautiful machine!!!

       The next step was to properly balance the B-25 and find the CG. The manual suggested setting up the CG 5” back from the leading edge at the fuse. I set up my Great Planes CG Machine and carefully balanced the plane to see where the batteries would go.

       The batteries balanced out the B-25 just behind the cockpit. All I needed to do is figure out how to mount them there. I had just finished building the glow driver system battery (below) out of three CP-2400SCR cells which will give me about an hour of continuos glow driver power. I purchased these cells from Batteries America.

       I decided to use a Hydrimax Ultra 4200 mAh NiMH four cell battery for my on board radio gear. I built a battery tray to fit both of these batteries one atop another as seen below.

       Once assembled the battery tray was glued into place on top of the middle set of stringers in the fuse.

       A second set of balsa strips were glued on top of the battery tray for added strength.

       With the planes mechanics complete it was time to finish up the cosmetics. The covering was thoroughly cleaned with isopropyl alcohol in preparation for applying the “pressure” decals. A solution of soapy water (About one drop of dish soap per half gallon of water) was used to help position the adhesive decals on the covering. I used a spray bottle to wet the Monokote before applying the decals that had be presoaked in the water solution as seen below. It really helped to peel off the decal’s backing paper under the water’s surface to eliminate static electricity.

       Once the decals were in position I carefully squeegeed out the water solution from under the adhesive backed markings with a soft cloth, locking them in place. The decals were then allowed 24 hours to stabilize and “cure” to the covering. This is important as you don’t want to expose new decals to the sun’s rays or they will bubble and warp.

       In the photo below I used the plane as a “wing holder” to apply the star decal to the bottom of the right wing.

       A torpedo level was used to help position the waist star decals so that they were parallel to the top of the fuse at the wing tubes.

       Once the waist and tail decals had ample time to stabilize I sealed them with CA using the method I described on page #1. Sealing the decals on the tail will prevent them from peeling up once they are exposed to glow fuel exhaust.

       The last step before final radio programming was to properly charge the on board batteries.

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