---

Mount the Fiberglass Nacelle Covers

Before mounting the fiberglass nacelle covers the engine needs to be removed so that the nacelle cover will fit over the nacelle. Make sure the correct nacelle cover is used, as there is a left and right cover. The easiest way to tell the difference is the notch cut out for the landing gear strut. To mark the mounting holes for the nacelle cover I found it easier to use painter's tape to hold the cover in place as I marked the mounting hole. Use a Dead Center marking tool to mark the position of the mounting holes on the wing. Remove the nacelle covers and use a 3/32" drill bit to drill the mounting holes. Use a 1/8" bit to enlarge the mounting holes in the nacelle cover.
 

Use the #4 x 5/8" Phillips head screw to cut threads in each of the drilled mounting holes and then use thin CA to harden these threads. When the CA has cured use #4 x 5/8" Phillips head screws, #4 lock washers, and #4 flat washers to mount the nacelle cover to the bottom of the wing. A long shaft screwdriver is essential to mount the nacelle cover. I found the easiest way to do this was to shine a flashlight on the mounting screw from the landing gear bay, and then look through the crack between the firewall and the nacelle cover to place the screwdriver on the head of the screw.
Don't worry if it feels clumsy putting this nacelle cover in place on the wing, because you're going to get a lot of practice as the assembly of the plane continues. The nacelle cover will be put on and removed several times as we continue.

Working gear doors have always been a bit difficult to design and implement, but Top Flite has done an outstanding job of accomplishing this very task. Their design for working gear doors is very well done and very sturdy.

The first step to installing the gear doors is to remove the nacelle cover from the wing. Locate the areas on the inside of the gear doors where the hinges will mount. Use a hobby knife to scrape away the black paint where the hinges will mount to the gear doors.

Use tape to secure the gear doors in place on the nacelle cover. At this point I found I had a problem with one of the gear doors as it was pretty warped and would not mount correctly on the nacelle cover. I was able to correct this by running hot water over the gear door to heat it up. Then I twisted the gear door in the opposite direction of the warp. A few minutes of doing this straightened out the gear door so it fit flush on the nacelle cover. Use a razor blade to cut off 1/8" from two nylon ball links, then use a 5/64" drill bit to drill out the inside of the ball link. These hinges will be used for the rear of the gear doors. Now cut 1/6" off of two ball links and construct two more hinges, which will be for the front of the gear doors.

The ball links are mounted to the door hinges using 2-56 x 3/8" screws, # 2 lock washers, and #2 flat washers. The orientation of the hinges is very important so make sure to refer to the instruction manual as they are installed in the plane. Four nacelle hinges are constructed by mounting 0-80 ball link ball in the bottom hole of each hinge using a 0-80 nut and a drop of threadlock to secure the nut in place. Be careful here as I had one ball link shaft break off as I was tightening down the nut, which caused me to be short at the end of the assembly of the plane. Build two "A" hinges and two "B" hinges, referring to the instructions as a guide for doing this. Referring to the pictures in the instruction manual use coarse sandpaper to roughen the inside of the nacelle cover where the gear door hinges will mount

Use 30-minute epoxy mixed with microballons to glue each hinge assembly to the gear doors where the paint was scraped off earlier. After the epoxy has set repeat this to glue the hinge bases to the inside of the nacelle cover. After all of the epoxy has set remove the tape from the outer doors and ensure that the gear doors open and close freely. If any epoxy has "oozed" out so that it interferes with the closing of the gear door it will need to be removed.

If for any reason the gear doors need to be removed it's important to NOT pop the ball links off of the ball mounts. If the door needs to be removed unscrew the door hinges at the ball link and remove the gear door this way.

---

Hooking up the Main Landing gear

 Glue a 1/8" x 1/2" hardwood dowel into a lever mount, with the end of the dowel should be flush with the backside of the lever mount. Hold the lever mount on the back side of the nacelle so that the outer edge of the lever mount is flush with the side of the nacelle, and the top flat portion of the lever mount is flush with the top of the nacelle. Use a 1/16" drill bit to drill a pilot hole for the mounting screw. Remove the lever mount and use #2 x 3/8" button head Allen screw to cut threads in the pilot hole and then harden the threads with thin CA. When the CA has dried install the lever mount in place using the button head Allen screw. Use the second hole in the lever mount to drill a pilot hole using a 3/32" drill bit; this hole will be to mount the bell crank. Use a #4 screw to cut threads in this hole and then harden the threads with thin CA.

A wooden bell crank that is made out of hardwood ply operates the gear doors. While the original wood doors are very durable some may find that repeated use over a long period of time may wear out the wooden doors. With this in mind one of our RCU members had made available a set of aluminum bell cranks that can be used in place of the stock wooden ones. They are available for a cost of $10, which includes shipping. If you are interested contact RCU member Mike-Rc (gear doors may be found here) to get a set of these bell cranks. I picked up a set so that I could show them here in this review.

To install the bell crank first glue a plastic washer to each side of the bell crank using thin CA. Now fit a brass bushing into the bell crank and install it in the lever mount using a #4 x 5/8" screw. Tighten the screw tight enough to hold the bell crank in place, but it still needs to be able to move freely. Bend a hook in each end of the provided spring approximately 3/8" from the coils of the spring. One end of the spring is hooked through the hole in the bell crank, and the other end is hooked into one of the notches in the lever mount. Start in the middle notch, but this can be adjusted if needed for better operation of the gear door. Test the operation of the landing gear in that it moves freely and does not bind. If needed trim the bell crank in order to provide free movement of the landing gear strut. Cut a 4" pushrod so there is 3/8" of thread remaining and then a total length of 2-1/2". Bend the pushrod to match the diagram provided in the instructions.

At this point I was a bit perplexed in constructing the other gear door pushrod. The instructions do not mention what to use to build this. I finally a found small piece of threaded rod that is used for this in the bag that contained all of the screws, but it took me some time searching to find this. Once the pushrods are constructed use epoxy mixed with microballons to glue control horns to the inside of the gear doors, attach the pushrods to the bell crank and use this as a guide in placing the control horns.

Attach each gear door and work the retracts to adjust the length of the pushrods so that the gear door completely closes without binding. I found it easier to disconnect one door to adjust the pushrod of the other door. With both doors adjusted use a can of compressed air to cycle the landing gear and make sure that the gear doors completely close without binding.

These pictures can be used as reference for the workings of the landing gear and gear doors.

---

Mount The Cowl

Once again, the nacelle cover needs to be removed for these next steps. Use 5/32" drill bit to drill holes through the firewall at the 8 precut marks for the cowl mounting tabs. As you can see in the picture place something solid behind the firewall when drilling the holes to prevent accidentally drilling holes in the fuel tank. Use a 4-40 x 3/8" Phillips screw and 2 #4 washers to pull the blind nuts in place in each of the holes that were just drilled. Use thick CA to secure the blind nuts in place, making sure to not get any glue in the threads of the blind nuts. There are two different sizes of cowl mounting tabs: the long ones are marked "A" and the short ones are marked "B". One of the "A" tabs will have a larger hole in the top of it. Press a 4-40 blind nut into the larger hole and use thick CA to secure it.

Use threadlock on the screws to install the cowl mounting tabs and install each mounting tab with 2 each 4-40 x 3/8" Phillips screws, #4 lock washers, and #4 flat washers. When installing the tabs the "A" tab with the blind nut in it is installed at the top of the firewall, with the blind nut to the rear. Install the remaining tabs so that the blind nuts are to the front of the nacelle. In the cowl ring there are 3 larger holes pre-drilled and one smaller pre-drilled hole. Install 3 4-40 blind nuts in the 3 larger holes.

When installing the 4-40 socket head screws that mount the cowl it's important to remember that when the plane is assembled it's going to be rough to get into the cowl when removing it, and therefore could lead to the screw falling out and being lost. I will admit that this is not my idea and that I picked it up from the thread about this plane here on RCU, but use fuel tubing to retain the screw in place. Insert the 4-40 x 1/2" socket head screw, #4 lock washer, and #4 flat washer through the mounting tabs (and through the cowl ring for the tab at the top of the cowl) and then slide a small piece of fuel tubing over the screw. Now when the cowl is removed the fuel tubing will keep the screw from falling on the ground and being lost. As you can see it is about impossible to get an Allen wrench straight on to the cowl mounting screws, so a ball end wrench is mandatory for this plane. The ball end will allow the screws to be turned from an angle so that the cowl can be removed. And as you'll see later a long shaft wrench is needed as well in order to access the one screw at the top of the cowl ring. Great Planes makes a set of ball drivers that are perfect for this application, the part number for these can b found in the instruction manual. As can be seen above, the cowl ring is mounted on the mounting tabs.

Leaving the cowl ring in place cut the ring so the engine muffler can be installed on the engine. The cowl now needs to be rough-cut in order to allow it to slip over the head of the engine. Use a cutting wheel on a rotary tool to rough cut this hole. The hole will be cleaned up later on as we finish up the installation of the cowl.
 

For the next step the inboard portion of the wing with the nacelle needs to be mounted on the fuselage. Slip the three wing tubes through the fuselage and slide the inboard wing section in place. I placed a small board across the wing tubes on the other side of the fuselage and placed some weight bags on the boards to counter the weight of the wing section. This let the fuselage sit level. Position the fiberglass carburetor intake in place on top of the wing and mark the position of the mounting holes. Use a 1/16" wrench to drill mounting holes, cut threads in each hole with the #2 x 3/8" Allen Head Button screw, and then harden the threads using thin CA. When the CA has cured install the carburetor intake using #2 x 3/8" Allen head button screws.

Now slide the cowl into position on the nacelle. As you can see in the picture above there is quite a bit of down thrust built into the engine mounts. Because of this the user will need to make a compromise between centering the propeller in the cowl and aligning the cowl with the nacelle cover. The user needs to position the cowls so that they look "about right". Looking at the cowl from different angles while doing this will help to get it positioned correctly. When satisfied with the position use thin or medium CA to tack the cowl to the cowl ring.

Without breaking the cowl ring free from the cowl carefully remove the cowl. Use 30-minute epoxy mixed with microballons or milled fiber to build a fillet all the way around the cowl ring on both sides of the ring. When dried remount the cowl and cut an access hole in the top of the cowl that will be used to insert a ball driver to access the mounting screw. With the cowl mounted now cut the cowl in order to allow the muffler to be mounted. Also clean up the hole cut for the engine, ensuring to add a hole for the glow diver to be attached to the engine.

Since this is a 3-line fuel system a mount in the cowl is needed for the fill line. Included with the plane is an end for the fill line, so we need to build a mount in the cowl. This is actually very easy to do with a scrap piece of balsa and 9/32" brass tube. Cut the scrap balsa to approximately 1" square and shape one side to fit the curve on the inside of the cowl. Drill a 9/32" hole in the middle of the block and insert the brass tube. The tube needs to be cut so that it just extends to the outside of the cowl. This is then epoxied into the plane inside the cowl. To mount the replica engine first sand the side of the replica to remove the paint from the plastic.

Cut out two of the cylinders from the replica. This is to allow air flow through the replica to the "real" engine inside of the cowl. On the remaining cylinders us a small drill bit, or the tip of a hobby knife, to make small holes for the replica pushrods. Each cylinder has 2 pushrods on it. Insert the replica pushrods and put a drop of medium CA on the inside of the replica engine to hold the pushrods in place. Next mount the replica engine inside of the cowl so that it sit evenly in the cowl. Use thin CA to secure it in place. If needed, enlarge the hole around the center of the replica engine in order for the "real" engine to sit without rubbing or vibrating against the replica.

The last bit for installing the cowl is to install a needle valve extension. As you can see in the pictures I had to have my needle extension exit at the bottom of the cowl. I really didn't want to do it this way, but because I couldn't reverse the carb on the FL-70 engines I didn't have much choice. I used a tried and true technique for installing items such as this. First tape a strip cut from a file folder to the nacelle behind the cowl. Position the needle extension and make a hole in the file folder. Without moving the strip of folder install the cowl into position and then transfer the hole to the cowl. Drill the cowl to install the needle valve extension.

Hook up Flaps and Ailerons

As you can see in the picture above there are a lot of servos in the wing (in fact there are two more servos for the throttles as well, for a total 8!). The flaps and ailerons all use standard servos. The mounts for the servos are all pre-constructed with the wood mounting rails already glued to the hatches. I did find a couple of the glue joints to be a bit loose, so it would be a good idea to run a bead of medium CA around the base of each servo rail just to make sure it's secure. One mistake I see a lot in mounting servos is that many times they will be mounted directly to the wood in installations such as this. This is not a good idea because that contact with the wood will directly transfer vibrations to the internals of the servo. If direct contact such as this occurs it bypasses the benefits that the servo grommets give. To avoid this contact I will place a small metal ruler between the servo and the hatch when marking the mounting holes. This gives enough separation to keep vibrations out of the servo. Mark the holes with a Dead Center marking tool and drill the mounting holes with a 1/16" drill bit. I like to use #2 servo mounting screws from www.microfasteners.com for mounting servos, as the socket heads in these screws aren't prone to stripping like regular screws are. After using a screw to cut threads in the mounting hole the threads are then hardened with thin CA.

The servo is then mounted to the hatch. The hatches are mounted into the wing using #2 x 3/8" Allen head button screws. As with all other screws in wood the threads are hardened with thin CA prior to mounting the screw in the hole. For each aileron a 6" servo extension is added to the servo wire. Heat shrink tubing is provided with the plane and should be used on all connections such as this to prevent the joint from pulling apart. Simply slide the heat shrink over the joint and heat it with a heat gun to shrink the material. Although the instructions say to use a heat gun or lighter to shrink it I would advise against using the lighter. I have used them in the past and it's possible to melt and distort the servo connections if too much heat is applied. This is why I prefer to use the heat gun. As with the throttle wires, make sure each wire is properly labeled.

With all the servo hatches in place the pushrods for the ailerons and flaps need to be installed. The TF B-25 includes solder clevises for all the pushrods, which I really liked to see. To install the control horns first use a ruler to mark their location on the control surface. When mounting the control horns the ailerons are mounted 3/16" from the edge of the aileron and the horn on the flaps is 3/8" from the edge. One thing I do want to point out is that even though backs for the control horns are provided they are not used to mount the control horns. The horns are mounted by directly screwing in #2 x 3/8" Phillips head screws into the control surface. I like to use a couple of craft sticks and two clamps to center a control surface such as this when I am setting up the pushrods.

Plug the servo into the receiver and turn it on in order to center the servo and then measure the pushrod for the proper length. Use proper soldering techniques to solder the clevis on the pushrod at the length that was previously marked. Install the pushrod on the control surface.

---

Assemble the Tail

Assembling the tail starts with installing the rudders on the vertical stabilizers. These are mounted with the same smaller hinge points as the ailerons use, and are installed in the same manner. While the epoxy is setting on the rudder hinges move on to the elevator. The TF B-25 has a split elevator that is connected with an elevator joiner wire. Use a piece of sandpaper to rough up the torque arm portion of the elevator joiner wire so that the epoxy will get a better grip. Slide 2 plywood elevator joiner mounts onto each side of the elevator joiner wire. Once the mounts are on the wire use thin CA to glue the two mounts together.

Before installing the elevator mounts to the trailing edge of the horizontal stabilizer it's very important to make sure that it is straight. Slide each elevator half onto the joiner wire and place on a flat surface to see if the wire is straight. If both sides don't sit flat then bend the joiner wire until both sides do sit flat. Cut away the covering on the trailing edge of the stab and epoxy the elevator joiner mounts to the stab. While the epoxy is mixed use a little bit to install the stabilizer dowel in the hole in the front of the horizontal stabilizer.

Install the elevator hinge points in the same way as all others already installed. When installing each elevator halve also put a bit of epoxy into the hole for the elevator joiner wire. Install both elevator halves and set aside until the epoxy sets. While the epoxy is setting install the rudder servos into each servo hatch in the same manner as the aileron and flap servos were installed.

When the elevators are set install the rudder servos into each hatch using #2 x 3/8" Allen head button screws. Use the string that is installed in the stabilizer to pull the rudder servo wires to the middle hole. Use heat shrink on the connectors and connect each rudder wire to each side of a Y-harness, and then connect the Y-harness to a 24" extension that will run to the front of the fuselage. The vertical stabilizers are installed using 2 4-40 x 3/8" socket head screws on each stabilizer. Use a bit of threadlock on each screw before installing them. Next install the rudder control horns on each rudder; this is done in the same manner as the ailerons were done.

The rudder pushrods are built from threaded rod with a metal clevis on the servo end and a nylon clevis on the rudder side. Connect the rudder servos and center them before installing the rudder pushrods. The elevator servo is the only high torque servo used on this plane, and is installed in the precut servo mount in the horizontal stabilizer. Mark, drill, thread, and harden the mounting holes the same way as the rest during this installation. The pushrod is soldered together in the same manner as the aileron pushrods.

A tube is provided to run the servo wires to the front of the airplane. However, I had a hard time getting the wires all the to way the end of this tube, so I ran the wire inside of the fuselage instead. The tail assembly is installed by inserting the front dowel pin into the hole in the fuselage. The tail assembly is secured using 4-40 x 1-1/2" socket head screws, #4 lock washers, and #4 flat washers. I put a bit of threadlock on these bolts as well as a little added insurance to keep the tail securely attached to the plane.

---

Mount the Nose Gear

The nose gear is controlled by a separate servo mounted in the bottom of the fuselage behind the cockpit. The nose wheel is connected to the servo by two steel cables that steer the nose wheel. The steel cables are connected to a brass coupler, which will be screwed into a metal clevis that will connect to the servo arm. To assemble the wire first slide a copper swage over the wire, through the brass coupler, and then back through the swage. Use pliers to crimp the swage and secure it on the steel wire loop. I found the swage to be very small and I had a very hard time getting the second wire into it.

Install the steering servo into the mount at the bottom of the fuselage. The steering wires are routed to the nose wheel bay through two plastic guide tubes.

Disassemble the nose gear strut and file a flat spot on the rod to help the setscrew hold tightly. Reassemble the nose gear and set the retract mechanism into the gear bay. Mark the location for the mounting holes, then drill and cut threads in the same way as the main landing gear was done. Use #6 x 1/2" Phillips screws to mount the nose gear in place.

Shown in the picture is the 0-80 ball link that broke earlier as I was installing the main gear doors. Because of this breaking I was short one ball link. According to the instructions two ball links are installed on each side of the nose gear strut and the steering wire is then looped over it to steer the gear. I had to do it a bit differently because I was one ball link short. What I did was to simply loop the wire through the holes on each side of the nose gear strut. Also, as this area was really tight I didn't feel that I could get the brass swage threaded with both wires. I cut two 1/16" diameter brass tubing and used that to crimp on the steering wire. The axle for the nose wheel will need to be cut off with a cut-off wheel on a rotary tool.

While not absolutely necessary, the hinge wells for the front gear door can be painted grey to match the color of the covering. I used paint intended for plastic models, as this is what I had on hand to do the job. The hinges for the front gear door are spring-loaded and should spring to the "open" position for the door. This is because it's actually the spring action that opens this gear door and not the motion of the landing gear. The gear strut will engage a wooden lever which will pull the door shut as the gear retract. The lever is constructed with a 2-56 ball link bolted in place in the pre-drilled hole and a 4-40 x 1" socket head screw used as a pivot point. The socket head screw is inserted through a brass bushing before it is put through the lever.

Use epoxy to glue the front gear door in place. Place epoxy on each side of the spring loaded hinge and install the gear door to the fuselage. While the epoxy is setting up tape the gear door in place. Use something to insert into the gap between the fuselage and the gear door. Here I used two nail files that I had on hand, as they were the perfect thickness. Once the epoxy has set use medium CA to glue a control horn on the inside of the gear door. This will attach with a pushrod to the gear door lever. Retract the landing gear and then use a long shank ball driver to adjust the linkage. Cycle the front gear to ensure the proper movement of the landing gear and gear doors, and make any necessary adjustments.

NOTE: In the initial run of kits for this plane there was a misprint on the needed air tank if Robart retracts are being use. While the plane was originally designed to use a small air tank, the stock number listed in the instruction manual is for the large air tank available from Robart. Actually, it may be better to use the larger air tank as it will give more retract cycles than the smaller air tank will. The plane was designed to have the small air tank installed just forward of the cockpit, but the larger tank will not fit into this location. If using the large air tank the area directly behind the cockpit is the perfect location to place this tank. Top Flite has a template for making mounts on their website.

The cockpit is assembled by first gluing two 3/16" x 3/16" x 5" balsa sticks to each side of the cockpit, just slightly above the edge of the front shelf in the cockpit. Using the cockpit floor as a guide drill 4 1/16" pilot holes in the balsa rails. Use Allen head button screws to mount the cockpit floor. Use black paint to paint the parts of the cockpit that will be visible when the plane is assembled.

The instrument panel is made from the two instrument decals, the plastic instrument panel back piece, and the wooden instrument. Use spray adhesive to attach the decal with the instrument dials to the front of the black plastic panel back piece. Trim off any excess around the edges of the panel. Now glue the wooden piece on top of the panel decal. Finally, place the last decal over the top of the wooden panel middle, lining up the holes in the instrument panel with the dials below. The pilot figures are simply profiles of a pilot. Cut the appropriate decals and attach them to the wooden pilot profiles. Glue the 2 full size pilots to the cockpit floor by CA'ing them into the provided slots. Complete the cockpit by adding the seat backs and the control yokes to the cockpit. At this point the cockpit floor will be removed until the plane is put back together for final assembly.

The mount for the retract air control valve is made from the supplied ply parts. Assemble the mount and secure the air control valve. Install a 0-80 ball link ball on the control shaft of the valve. Mount the retract servo and the air control valve beneath the cockpit on the right side of the fuselage. The retract servo needs to be adjusted so that it has no more movement than 1/4" of travel.

Provided are two ply mounts that will serve to hold the receiver in place beneath the cockpit floor. Install these with medium CA. There are 4 slots in the floor to glue these mounts in, so you can tailor it to fit your specific radio gear. Use the supplied parts to build the air fill valve mount. Mount the fill valve in the mount and adjust it so that the end of the fill valve is 7/32" from the top of the ply side rails. With this build install this in the plane on the left side of the fuselage in the pre-cut mount hole. The air fill valve should be installed so that it sits flush with the outside of the fuselage side.

Use epoxy to glue the air fill valve in place. Included are several wire management "loops" that can be used to tame down all of the wires and air lines that will run in the fuselage of this big bird. One of these guides is glued in place behind the retract servo, but the other guides can be placed as needed. One thing I found that really helps keep down the clutter is to join each set of retract lines together. I do this by using small pieces of fuel tubing slipped over the lines to hold them together.

The receiver is wrapped in foam rubber and then mounted in the cockpit area. Air lines for the main gear are run back through the fuselage and then a "T" fitting is used to branch out to each main landing gear. Quick disconnects are provided with the plane to facilitate removal of the wings if needed. Here you can see the completed cockpit area.

---

Radio Installation

For the review of the Top Flite B-25J Mitchell I had the opportunity to try a new product that I have not seen before. These are new power systems from Duralite batteries. These systems are unique as they are Lithium chemistry batteries that are regulated down to the voltage of the receiver that is being used. Because of this there is a constant voltage available to the receiver even when the battery drained. These batteries also have the advantage for being able to handle large current draws from the servos and flight system in today's modern planes. The setup of these batteries is a bit different than some people may be used to. The battery itself is a 2-cell Lithium-Manganese battery that has 2 wire sets coming out of it. The heavy gauge wire is the power tap and this is plugged into the voltage regulator. The second wire is the charge lead which will be used to recharge the battery. The second component is the voltage regulator. This is plugged into the power tap from the battery. The regulator has it's own power switch that is used to turn on power to the system. There is a jack attached to this switch which is used to check the voltage level of the battery. Duralite has an adapter available that will go from the voltage regulator into your radio system. All power connections in these systems utilize Deans connectors to handle the higher voltage loads on the system. Duralite Lithium-Manganese Receiver Batteries Non combustable chemistry Non flammable if punctured or overcharged Highest Discharge - 20c continuous with 40c bursts Great low temperature toleranace High charge rates up to 10c Stay Balance circuit built into pack - no need for   external balancing Longer life cycles than li-polymers Dual lead system - choice of power output leads/connectors, plus charging lead w/yellow connector 2200 mah - 2 cell Li-MN -7.4 volt Price: $97.95 Flight weight: 5.8oz (165 grams) Size: .5 x 1.75 x 5.5in (T/W/L) Discharge Amperage: 44Amp (20C) Charge Rate: 1AMP Voltage Regulator High Current Regulator The High Current version of the DURALITE regulator uses 16 gauge wire and the Ultra Deans connectors to reduce resistance in the wiring and the connectors which improves the regulators overall efficiency. We have found that the minimum voltage is significantly higher when the HC-wiring is used. We hope to have another graph of this same situation that will show as soon as the weather co-operates this spring. Surface mounted electronic components. Compact heat sink. Full RF filter in and out delivers highest performance. Rated at 7.5 amps with 10 amp spikes Unique Hybrid Pulsing Design Designed for 6 - 8.4 volts Specifically designed for use with the DURALITE PLUSTM Battery but also works well with other battery chemistry types Voltage Regulator with Fail Safe Switch, 7.5 amp w/standard 22ga wire, 6.0 volt If the switch were to fail regulator stays in the on state until you unplug it from the battery. Not suitable for ignition applications due to fail safe feature. Price: $49.95

Bringing in all of the servo leads to the receiver. Labeling each wire will help to keep them all straight and organized There is a tube provided to run the receiver antenna through. Use a strain relief to keep the wire from pulling out of the receiver if any pressure is placed on the antenna wire. The antenna wire isn't long enough to extend all the way to the tail of the plane. Tie a piece of string to the antenna wire and pull back to the tail and tie off the string. This will keep the antenna from working it's way back up the antenna tube. The on/off switch is mounted on the left side of the fuselage directly below the cockpit. The Duralite power system provides a jack used to check the power level of the battery. This jack is mounted here with the switch. Duralite battery installed where small air tank should go. Duralite power regulator. Zip ties used to secure regulator behind front landing gear bay. Radio installation completed. All components in place. Power lead from battery is routed back underneath cockpit to the voltage regulator located behind the landing gear bay. The charge jack for the battery is tied off in the landing gear bay and can simply be pulled out to charge the battery.

---

Mount the Inboard Wing Panels

The design of the Top Flite B-25J Mitchell leaves the end user with several options as to how to transport the plane to the field. The wing is actually made up of 2 sections; the outboard wing section and the inboard wing section that has the engine nacelles on it. If transportation space is limited it's possible to leave both sections off and assemble the entire wing at the field. I chose to instead install the inboard wing sections on the fuselage and transport to the field assembled as such.

1 30 x 440 mm main wing tube and 2 10 x 305 m wing tubes support the wing sections. The smaller wing tubes are secured with 4-40 socket head screws, which also secure the wing sections to the fuselage. These tubes come with one end already tapped to accept the socket head screw. Slide these sections into the wing section and install the 4-40 x 1" socket head screw through the wing section into the wing tubes. Slide these wing tubes into the fuselage section and connect all of the wiring and air connectors. Because I plan to leave these assembled I used heat shrink on all of the connectors to ensure that they remain secure. With all the connectors in place slide the wing section all the way tight against the fuselage.

Turn the fuselage around and slide the other wing section onto the wing tubes. Once again secure all the wires and air connections and slide the wing section tightly against the fuselage. Ensure that both wing sections are tight against the fuselage. Use brass tubing to make a small drilling jig to drill pilot holes in the wing tubes. First place a 1/8" piece of tubing into the screw hole in the wing. Then place a 1/16" piece of tubing inside of the first brass tube. Now use a 1/16" drill bit to drill a pilot hole in the wing tube using the guide to keep the drill straight. Ensure that you drill all the way through the wing tube.

Remove the wing section and re-drill the holes in the wing tube using a #43 drill bit. Use a 4-40 tap to cut threads into the wing tube. After tapping the tube use a file to remove any metal burrs that may be left around the hole. Reinstall the wing section and secure in place using a 4-40 x 1" socket head screw. Use a drop of threadlock on the screw to secure it in place on the wing tube.

---

Mount the Outboard Wing Panels

The outer wing panels are installed in a similar manner to the inner wing panels. Wing tubes are used to support the wing using a socket head screw at the rear wing tube to secure the wing to the tube. The difference here is that a nylon bolt is used at the front of the wing to secure it. This bolt is installed at an angle along the front of the wing panel and is hidden from view by the molded plastic oil cooler. The instructions call for determining which oil cooler went on each wing, but as I looked at them I found both oil coolers to be identical. The oil cooler is placed in position on the wing and then use a marker to outline the oil cooler. Use a hobby knife to cut through the covering 1/16" inside of the line. Remove the covering from this area, leaving the black covering in place over the air scoop. Use medium CA to glue the air scoop in place on the wing.

Install the 2" nylon bolt in the front of the wing panel and tighten it down against the inboard wing panel. Use the same method to drill and tap the wing tube as we did for the inboard wing panel. Use a 4-40 x 3/4" socket head screw to secure the wing panel in place.

---

Scale Features

Use medium CA to glue the plywood rubber band hooks on the inside of the nose-gunner window. To prepare the parts of the nose section to be joined first use medium grit sandpaper to scuff the edge of the bottom piece as well as the edges of the nose canopy. Align the parts and use tape to hold the nose canopy and bottom section together.

The nose canopy and bottom section are joined using thin CA. Maybe it's just me, but I never have any luck using CA around clear pieces on a plane. No matter how careful I try to be CA always seems to wind up in the clear portions. I would rather use different method than had been used to construct the nose portion of the plane. I followed the instructions and use thin CA for gluing the nose canopy parts together, and tried to be very careful as I did this. However I still had CA run where I didn't want to, which resulted with CA in the clear window portions of nose canopy. When I tried to remove it with CA debonder it clouded the canopy. I was able to "clean" this up by "painting" that portion of the nose canopy with clear fingernail polish which did a pretty good job of filling in the clouded portion of the canopy. But it's still not perfect and if looked at close enough brush strokes can be seen where the nail polish was brushed on. It looks ok as long as you don't look too closely at it. If I were to do this again, or had to recommend and alternative method, I would use Formula 560 Canopy adhesive to join these parts together.

When the nose section is complete use rubber bands to secure the nose gun into position. Glue the supports to the bottom of the nose gunner cabin platform. Also, this platform can be used to secure the battery if needed. Parts are provided to assemble a platform that glues to the underside of this section. Unfortunately I could not use this because the Duralite battery that I used was too long to fit under the platform. This is the reason why I needed to move the battery to the cockpit area of the plane.

Glue the cabin platform into position on the plane. If Top Flite missed on anything big in this plane I would have to say it was the paint used on the scale parts. While I compliment TF for putting the parts in the plane, the colors were all off. What should have been a interior green turned out to be an almost neon green, and the leather of the nose gunner seat turned out orange. Hopefully they can correct this in later editions of this plane as I feel that correct colors would add a lot to this great warbird. Use the provided Allen head button screws to secure the cabin back wall to the structure of the plane. I made sure to install these so that I could access them later on so I could remove the back wall if any servicing is needed of parts behind the wall. Use medium CA to glue the cabin floor to the platform.

Glue the tops of ammo boxes on the ammo boxes and then glue the boxes to the ammo tray. Then glue the ammo tray to the cabin floor as shown. I would recommend using epoxy to glue the ammo cans to the ammo tray. I initially used medium CA for this and while I was breaking-in the engines the vibrations caused them all to break loose. I reattached them using epoxy and so far that seems to be holding. Glue the kneeling pad to the post on the floor of the cabin. Position the canopy on the plane and use Allen head button screws to secure the canopy in place. Unfortunately I did not have enough of these to complete this. As I state in my summary below I had a problem with these screws "stripping" out as I installed them, even though I used several different wrenches. I used #2 socket head screws from www.microfasteners.com to install the canopy in place.

The scale features for the tail gunner are installed in the same manner as the nose section. Scrape the paint away from plastic parts before gluing them together.

Glue all the plastic scale parts in place including the tail gunner profile figure. I used Formula 560 Canopy Glue to install the tail gunner canopy in place. I had another issue with the tail section similar to the nose section. While breaking-in the engines the vibrations broke loose the gunner figure. To fix this I drilled through the cabin floor and used small screws to secure the figure in place in the cabin.
 

The top turret gun is assembled from two machine gun barrels and the gun unit. Included in the kit is a circular piece of steel grey MonoKote that should be ironed down where the top turret will be mounted.

The back edge of the top turret guns should be placed 5" behind the back of the cockpit. Mark and cut the MonoKote where the guns will be mounted and glue the guns in place. I used the Formula 560 adhesive again to glue the top turret in place on the top of the fuselage. I did have to trim the gun slots of the canopy a bit in order to get the turret to fit properly over the guns.

Gluing machine gun barrels into each waist gun window assembles the waist gun windows. Place the waist gun window on the side of the fuselage and mark it's position. Make sure to get the windows on the proper side of the plane. It was impossible to get them wrong on my plane as the invasion strips on both the fuselage and the windows would only line up one way. Use epoxy to glue the waist gunner windows in place on the fuselage.

The side gun packs are assembled by gluing the gun barrels into each gun pack. The instructions called for the bottom gun to extend 3-1/2" from the pack, but I was unable to do this, as there just wasn't enough gun to extend that far. I glued the gun in as far out as it would go and then matched the other gun in the pack with it so that they were even. The side gun packs are molded to fit the curve of the fuselage so they need to be mated to the sides of the plane. In addition, the painting of the gun packs should also match up with the covering of the fuselage. I would like to compliment Top Flite here as I can't think of any other plane that I've ever seen where painted parts matched the covering scheme as well as they did here on the B-25. They definitely did a great job here. When positioning the parts attention needs to be paid to any switches, charging jacks, the air fill valve, and anything else installed on the sides of the plane. I used tape to hold the side guns in place while I traced them.

With the outline of the side pack guns traced out use a hobby knife to cut the covering away, cutting approximately 1/16" inside of the line that was traced. After cutting the covering away use a paper towel with alcohol on it to remove the traced lines. Go back over the covering with a covering iron to seal down the edges around the cut away area. Use thin CA to glue the side pack guns in place. I found that it helps to glue one part of the gun at a time. I started with the bottom of each pack and then when the CA was dried I would then do the top pack.

The homework that Top Flite put into this plane really shows in parts as simple as the ADF "Football" antenna mounted on the bottom of the fuselage. This part would be very vulnerable to be broken off while transporting or storing the plane. To prevent this Top Flite has designed this part so that it mounts with strong magnets. This allows the antenna to be removed for transportation or storage, and if the antenna is accidentally "bumped" it will simply come off and can easily be reattached because it's mounted with the magnets. Included in the ply parts is a template for cutting the holes for mounting the magnets in the fuselage. I used a sharpened piece of brass tubing to cut the holes for these magnets. Once the holes are cut use thick CA to mount the magnets in the fuselage.

Once the magnets are mounted it's very easy to install and remove the ADF "Football" antenna.

Top Flite has included a very good set of decals to duplicate the paint scheme of the "Executive Sweet", which the plane is based on. While the decals are sticky backed the instructions recommend an alternate way of installing them. They call for using water with a mild detergent for installing the decals, but I prefer to use Windex for this. Spray Windex on the area where the decal will be installed. Cut the decal away from the decal sheet and place it down on the area with the Windex. The Windex will allow the decal to be moved into position without the adhesive on the back of the decal "grabbing" hold. When the decal is in place use a paper towel to push all the Windex out from under the decal. Also use a scrap piece of balsa to burnish the decal into place on the plane. Use the illustrations in the manual, as well as the box art, to indicate where to place all the decals on this plane.

---

Balancing the Plane

The instructions call for the B-25 to be balanced at a point 5" behind the leading edge of the wing, measured at the fuselage side. The instructions also specify to balance the plane with the landing gear in the down position. I must admit that I was a bit worried about the balance of the plane. The plane already weighed over 19 pounds and I was afraid I might need to add more weight to get it to balance properly. Once I had the plane up on the balance stand I was pleasantly surprised, as the plane only needed 2 ounces to come to a perfect level. As you can see in my last picture, I used very "precise" weights to add to the plane! With the plane balanced the final dry weight was 19 pounds 8 ounces.