Tail Group

We have provided die-cut tailpieces and fuselage doublers. You will need to use a scissors or knife to cut the pieces away from the die-cut sheet in spots. We want them to stick to the salvage for protection during shipping. I usually start with the tail group and wing. Save the scraps for later use.

1. The first thing to do is trim the fin parts and horizontal stabilizer from the plastic sheets. Notice that the vertical fin has two pieces. Locate them and fit them together--they only match up one way. Goop the joint and use a small piece of Scotch tape or a piece of the colored packing tape on each side of the joint to hold it together. Refer to fig# 1 for the fin assembly diagram.

3. Lay the horizontal stabilizer on the table in front of you with the back edge facing you and flip it so the two little holes are on the left side of center. These are the control horn screw holes and should be on the left side of the fuselage when the fin and stab are jointed. The horizontal stabilizer also has a little cut mark at one end of the fin to mark the hinge line for the elevator.

Just like the fin, pick the rib closest to the mark and cut along the surface of the rib on one side only. The other side will become the hinge. For a cleaner look, keep the control horn marks to the left side and cut the rib out from the underside so the top surface is the hinge. After slicing one surface, fold the elevator back and trim both of the cut edges to the next rib so the elevator will bend freely without binding on itself. To make the hinge work easier, use an X-acto knife or razor blade and make little cuts along the hinge of about ½” long and leaving about ¼” of material between them. Now work the elevator up and down several times to limber the hinge up.

4. To save weight, we usually do not cover the tail pieces with colored tape. We leave them white or you could spray them with a matching paint. Krylon spray paint works great on this plastic.

6. After the fin and stab are assembled, run a bead of GOOP (E6000, Shoe Goo, Household Goop, etc.) along each side of the fin and stab joint. Just do the top side then block them up so the fin is perpendicular and the stab hinge line is square with the side of the fin. Set aside to cure. If you don’t have GOOP or one of its derivatives mentioned above, you could use subfloor/panel construction adhesive or silicone RTV sealer.

When the glue is cured, locate the control horns provided in the kit and mount one on the rudder and one on the elevator. We have marked the position with two little holes in each place. As you look from the back, put the elevator horn on the left side of the rudder and the rudder horn on the right. If you happen to get the elevator horn holes on the wrong side, just punch new ones on the correct side in about the same position. Install the horns leaning forward.

Wings

Safety Note: Again, use a respirator or move outdoors when sanding and using adhesives of any kind.

Note: We have been advised by our friend and Boeing engineer, Bernard Cawley, that stacking two 2x4s on top of each other to obtain about a 3 inch rise off the table will produce a better flying "rudder - elevator" plane. This will give about a 5 degree dihedral and will produce much smoother turns. I wonder if this is how Boeing adjusts the dihedral of their 747’s? Just wondering.

Our wings are very easy to build and with the recommended power (.25 glow or speed 600 electric), should be plenty strong with the included spar. The wings are very thick and tough. If you build them according to our instruction, they should withstand normal flying and some limited aerobatics. The Big T is not designed to be an aerobatic plane and should be flown with grace and decorum. However, if you feel like pulling a loop or something, it will do it. Just keep in mind that the wings are stressed for positive “g”s, so outside loops and inverted flying--if it were possible (highly unlikely)--are probably out of the question. The wings are designed to be easy to fold up for storage or transportation. If you intend to haul a heavy load and use larger engines, you may want to strengthen the wing accordingly.

You will need a couple chunks of 2x4 wood and a 1” thick section of the jacket the wings came in for this next section. We will use them to establish the dihedral and aid in joining the wing halves.

7. First thing to do is sand the wing panels. Use 150 grit (medium to fine) sandpaper and smooth the surfaces out top and bottom. The smoother the surface, the better the tape will stick. The wing tip ends are usually rounded out so the wing tips have a nice smooth look. This isn’t critical, but looks nice and you could even shape the tip a bit so it doesn’t look so square. Just be sure to get both wing tips the same. You will need to glue a piece of sandpaper to a flat piece of wood to make a sanding block to aid in sanding the dihedral in the center joint of the wing panels.

Each wing panel comes in a protective jacket. Cut about a 1” strip of the jacket off (Fig #3A) and split it in two at the leading edge and the trailing edge. The portion that went over the top of the wing will make a cradle to hold the wing panels. Discard the other piece. Take a scrap of the 4mil from the tail sections and glue a bit of it to the flat surface of the cradle to strengthen it and hold it straight. On the table, stack 2 chunks of 2x4 wood and then place the foam and corrugated plastic cradle on it so the wing, laying upside down, can be supported in the center with the wing tips resting on the table (Fig #3B). The thickness of the 2x4's plus the foam cradle will establish the dihedral angle for the wing. Indecently, if you don’t have a couple pieces of 2x4's laying around, you can use anything that is about 2-1/2” to 3" thick as long as the sides are square and vertical and the foam cradle will sit well on it.

Now, you will notice that when you lay the wing upside down in the cradle and fit the wing panels together, there is a gap between them. Get your sanding block you just made and sand the ends of each wing panel until they fit nicely together (Fig #3B). There is a very easy way to do this quickly and accurately. Remove one of the wing panels and square up the end of the wing, on the cradle, to an edge of the 2x4 blocks and holding the sanding board against the vertical edge of the block, gently slide the sanding board back and forth while grazing the end of the foam wing. It will not take much sanding because you are only putting about a 2-1/2 degree angle on the end of each wing. Look, you have 6 feet of wing so if you don’t get it quite right, sand a little more until you do. The main thing is that the panels fit well with as little gap as possible. And really, the way we build the wings you could even leave the gap there and it wouldn’t matter that much. I just like things to fit neatly. Save the 2x4 chunks and foam cradle, as we will use them to help join the wings. First, let’s install the spars.

Note: we highly recommend Polyurethane wood glue. This glue will expand as it cures and virtually lock the spars to the foam. check out this link to see it being used: Installing spars 

After the glue cures, sand the ends of the spars to match the wing tips and dihedral angle at the center of the wing.

Tip: I’m right handed so I stick tape on from the left while stretching it slightly to right. You will get a smoother tape job if, while pulling lightly, you hold the loose end a couple inches off the object you are taping and use your hand or fingers to slide along the tape while smoothing and sticking the tape to the surface.

8. After the spars cure and tips are sanded, blow and wipe off the dust thoroughly and spray a LIGHT coat of 3M 77 spray glue on all surfaces. We have seen some folks get carried away with the spray glue and really it is a waste of glue to use more than a light coat on the foam. In some cases so much glue was applied that the tape bubbled because the glue wasn’t completely dry and it was still “gassing off”. So you should mist just enough on the foam to feel that it is sticky and evenly coated. If you can see the glue laying on the surface, you probably have more than needed and should let it dry thoroughly before applying tape.

9. After the glue dries, apply one strip of strapping tape over the spars (this is the nylon filament reinforced tape). Leave enough extra tape at each end to wrap around the end and onto the opposite surface about a ½”. Start by sticking tape around one end and stretching the tape across the wing panel. If you have trouble holding the panel still, try sticking the end of the tape to the table instead of wrapping around the end before pulling.

10. After the spars are on, it’s time to make the wings beautiful, so get your colored tape and let’s proceed. The main thing to keep in mind when covering wings is our basic taping convention (fig #3 C) for foam-and-tape planes. That is to always start at the back and work forward so an overlapping tape edge is never into the wind. Some times it may be necessary to break the rule, such as when doing a color scheme like my favorite--red, white, and blue. White or yellow do not go over other colors very well because they are rather transparent so you may have to lay the lighter colors down first so the darker colors will overlap. That may force you to have a tape edge pointing into the wind. That’s OK, just make sure the edge is pressed down tight and there are no bubbles or wrinkles in order to achieve a real good seal. The ideal is to start at the back edge and work forward if at all possible.

11. The wing panels should all be taped up by now so it is time to locate the 2mil corrugated plastic parts that will be used to join the wing halves. The top wing joiner is a die-cut part that looks like a puzzle piece down the center of it. Use a razor knife or scissors to cut the parts out, but be sure to keep them oriented the same way they were punched because they will have to fit together on the top of the wing.

  Also locate the 8”x10” rectangular shaped piece of 2mil corrugated plastic. This will join the bottom of the wing panels and form the hinge so the wings can be folded for storage or transport. Find the center rib and slice only one surface of the rib so the rectangle will fold easily. (note this could be already done for you, check to see if it folds in the middle - if not, slice one surface as outlined above)

Notice the strapping tape running chord-wise and pulled over the edge to the top surface of the wing.

You only have about one shot at this so be careful. An easy way to line up the hinge slice is to fold the joiner back on itself at the hinge, line up the hinge with the wing joint and stick one side, then unfold the other half and stick it. Stick three or four strips of strapping tape across the folding joint for a little extra insurance that a hard loop won’t cause the folding hinge to rip. Then use several strips of strapping tape, chord wise, (chord wise means from the leading edge of the wing to the trailing edge) on each side of the joiner. Put one on each side of the hinge, one in the center of each side of the joiner and one at the outer edge of the joiner. Pull the ends tight and wrap around the front and back edge of the wing with at least 3” stuck to the top surface of the wing. Cinch these down and pull them tightly while sticking to the top of the wing. Now use your colored packing tape to cover the white plastic joiner. I like to run the strips chord wise starting at the center and working out on each panel. Overlap the tape about a ½” and pull several inches around the front and back of the wing and stick to the top surface, just like the strapping tape. Pull the tape snuggly as you stick it down.

Notice the left wing joiner has strapping tape on it running chord-wise. Do the same on both sides.

14. Put the wing back together and hold it with a couple strips of tape across the joint fingers then use several strips of strapping tape running chord wise over the outboard edges of the top wing joiners and pull down tightly with about an inch stuck to the bottom surface of the wing.

  Unless you just have to be able to fold the wing, I would suggest taping the whole top surface of the joiner with colored tape running chord wise with about a 1/2” overlap until all the white plastic is covered. Pull the tape around the front and back of the wing to the bottom surface with special attention to the underside of the centering extensions on the front and back of the wing. Pull the tape over the extensions and tuck it into the underside then stick about an inch to the bottom surface of the wing.  

  Later, if you want to fold the wing, carefully cut the puzzle tabs out through the tape with a razor blade and peel the tabs from the wing. When readying the wing for flying, unfold the wing and press the tabs into the mating areas. Put several strips of packing or strapping tape across the center of the wing to hold the tabs down and the wing together. The wing rubber bands do a great job of tying everything together. I use 8 rubber bands and always criss-cross the bands over the center of the wing. In the event of a crash, the wing will pop off and several of the rubber bands will break, so keep spare bands with you.

Fuselage

  We have two fuselages for the Big T. One is designed for electric and the nose of the fuse is cut shorter for the motor/gearbox length and has a pocket cut for the battery pack. The other is designed for a .25 size gas engine and has the hole cut for a 6oz gas tank. Locate and cut out the fuselage doublers and punch out the 1/4-inch diameter holes. These are for the dowels that hold the wing down. And locate the firewall wood – it is the larger of the two chunks of wood.

  15. The first thing to do is use your medium sandpaper and sand the fuselage thoroughly. Leave the top edges square from the wing saddle to the tail as you will work with those a little later when installing the tail pushrods. Go ahead and round the bottom edges of the fuselage a little, but I would suggest holding the doublers on the side and only rounding from the back of the doubler to the tail section. Try to leave the portion of the fuselage under the doublers square.

Note: I am using a previously built wing to fit the dihedral to the top of the cabin.

16. Fit the doublers to the sides of the fuse and temporarily hold them in place with masking tape. Line both of them up with the wing saddle and the front windscreen of the plane. Be careful to get them both lined up the same and exactly with the wing saddle because the correct alignment of the wing depends on it. When you are sure that they are both correct, use a 1/4-inch drill bit to drill holes for the wing hold down dowels through the holes in the doublers. It is easier to drill in from both sides and meet in the middle of the foam than drive a hole all the way through from one side while trying to hit the other hole. Check the holes out with the dowels supplied in the kit. They should slide all the way through the foam and will help line the doublers up when gluing them on permanently. You may have to run the drill in the holes a time or two before the dowels go in.

  Now get the wing and set it on the top of the fuselage cabin. Because of the dihedral on the wing, you may have to sand a little relief at the center of the front and back of the cabin so the wing will set square on the top of the fuselage doublers. It doesn’t take much because the dihedral is not large but the wing may rock around on top of the plane if you don’t make an allowance for it.

 Take the doublers off and proceed with 17a through 23a for the electric version or drop down to 17b through 23b for the gas version.

Steps 17a through 23a cover the electric doubler, firewall, and COMBO setup.

  Then steps 17b through 23b will cover firewall and doubler setup for the gas-powered version using our gas COMBO.

Electric Version

For this process you will need to locate the firewall wood, and about a ¾” dia. spade drill bit, 1/8” and 3/32” drill bit, and paper motor mount pattern for the electric version. If you have our COMBO, locate the black plastic motor mount, aluminum clamshell-type motor strap (2 pieces), 4-40 x1” machine screws and blind nuts (T-nuts).

I usually put the door on the left side of the fuse. You can just see the door cracked open here.

17a.  If you are doing an electric, finish punching out the battery door on only one of the doublers. Decide which side you wish to access the battery from and make the door hinge by slicing only one surface of the rib that runs along the bottom of the door. The sliced rib will be on the inside of the doubler next to the foam so the door can open out.

Notice that the wire passages are punched through from the front to the radio compartment with a hole in the front for the speed control. You may wish the put the ESC under the wing but I like this area because it is easier to cool the unit.

This is can be done later and is in detail later in the text - step 23a

18a. Cut out the firewall pattern and glue it to the firewall wood. The firewall should come already cut to fit the fuselage. The electric fuselage is cut to fit our electric COMBO setup perfectly. Drill the 1/8” holes as indicated on the pattern for the electric version. We are using an Ernst adjustable long motor mount. These are made for gas motors, but they are very tough and perfect for our application. Spread the beams to match the holes indicated on the firewall pattern and tighten the set screws on the mount.

The electric motor will be held to the beams of the mount with the formed aluminum clamshell strap. Set one half of the motor strap between the beams, and position it all the way to the front. Drill 3/32” holes through the mounting holes in the clamshell for the #4x1/2” sheet metal screws. 

Drill a hole for the motor wires through the firewall in the center of the motor mount. This could be anything from ½” to 1”. I prefer the larger hole made with a hole saw or spade drill bit as it will allow cooling air past the motor and through the fuselage to the batteries. The batteries can be vented other ways though, and we will cover that later. Whichever you use, you will want to punch a channel from it to the front of the battery box. The size of the channel will be determined by the wire and plug you intend to use for the battery pack and motor. Our COMBO uses Anderson Power Pole plugs so you will need at least a 3/4 diameter channel. I find spade bits to be cheap and easy to use for this. Just be careful not to drill your hand or anything. And when you drill a hole in the plywood, be sure to hold the wood tightly with a pliers or Visegrip.

This is the main power plant assembly for our combo kit. How you mount your motor will depend on what mount you use. This setup is very versatile and will allow a variety of motors and gear boxes in the 550 to 600 class. If you use a gearbox with no off-set, you will want to move the motor mount up a bit so the prop shaft will come out in the correct place.

Then take some strips of colored packing tape and cover the strapping tape you just put on. The reason for the strapping tape is to reinforce the firewall and front of the fuse. The colored tape is simply to hide the strapping tape and make it look pretty again. Plus, the extra layers of tape will insulate the foam from the Goop glue that we will use to stick the doublers to the edge of the firewall with.

22a. To complete the doubler installation and strengthen the firewall, we suggest using a staple gun, hand tacker, or even thumb tacks or wire brads/nails to staple through the doublers into the edge of the firewall down both sides. This will make the front of the plane able to withstand an incredible amount of punishment.

  The last thing to do is to lay strips of strapping tape side by side on the underside of the fuse from the back of the doubler to the firewall. Push the tape down into and across the area where the landing gear mounts. Make the floor of the landing gear as smooth as possible so the gear mounts in solid. Use a blunt object to push the tape tight into the corners. Do the same along the top of the fuse from the back of the doubler to the firewall. Skip the radio compartment area. The ends of the tape stuck to the doubler should be about an inch long. Pull the tape ends tight to cinch the doubler down to the fuse.

Preparing the Fuselage for the Speed Control

23a. You should have a fuselage that is basically ready to cover. However, since we are setting up the electric version, you need to make a pocket for the electronic speed control (ESC). If you haven't already done so, cut a passage from the battery passageway to the radio compartment under the wing. Use your spade bit to drill a hole from the bottom front of the radio compartment at an angle pointing forward. Drill through until you intersect the passage from the battery box. Determine where you will need to cut a pocket in the front of the fuselage for the ESC. The length of the wires that are attached between the motor and the ESC may determine this. Depending on the ESC you use, you could install an electrical fuse between the motor and ESC for current overload protection, just in case you crash or forget to turn the throttle off if the prop gets stopped for some reason. The ESC included in the COMBO kit is self limited to 45 amps and will shut off power to the motor in the event of a mishap so a fuse is not necessary. If you make your wires long enough, the ESC could be located in the radio box under the wing, but I like to cut a pocket in the nose of the plane so I can get to the fuse if used. Plus, you can cover the pocket with packing tape and leave a slot or two to vent heat buildup away from the ESC. You may have to enlarge the passageways to the motor, battery, and radio box from the ESC pocket a little bit because you will have to route the wires from the ESC to all three places. Our speed controls come with Anderson Power plugs on the battery and motor sides. The battery plug is routed to the battery box as it provides the main power to the radio and motor from the battery pack. The small plug will go to the receiver and hook into the throttle channel so it will be routed up to the radio box. The remaining large plug will go to the motor, and one leg could have the fuse installed in it - if you need one. Refer to the wiring diagram for a pictorial view of the hook up. Some ESCs have a switch on it so the easiest thing to do is cut a slot in one side through the fuselage doubler for the switch to slide in and cut the foam away behind it so the switch can be pushed in snugly and glued in with RTV silicone sealer. Make sure the switch can slide freely on and off. The ESC in our Combo is self arming so no switch is necessary.

Gas Version – Setup for firewall, motor mount and fuselage doublers

  The fuselage nose is cut for most .25 size engines. We will describe the building process as if you purchased our gas-powered COMBO for the Big T. If you have your own engine, tank, and motor mount, use this as a guide as the installation will be similar.

  For this process, you will need to locate the firewall wood, paper motor mount pattern for the gas version, and 1/8” and 3/32” drill bits.

If you have our combo, dig out the black Ernst motor mount, 4-40 x1” machine screws and blind nuts (T-nuts), and #4x1/2” sheet metal screws that come with the Ernst mount.

The gas motor will be held to the beams of the mount with #4 sheet metal screws included with the motor mount. Leave the muffler off and position the motor all the way to the front (our Magnum .25), mark and drill 3/32” holes through the mounting holes in the motor for the screws. I find it easier to mark and drill one hole, screw the motor down tight and then mark and drill the other three holes. Make sure the motor is pointing straight ahead and not right or left. Remove the motor and mount from the firewall.

Tank and Throttle Cable Installation

20b. The hole for the gas tank is precut to fit most 6oz tanks and specifically our 6oz Dubro tank included with the COMBO. If you have a different tank, you can enlarge the hole as needed or add some foam scrap to wedge the tank in place.

On our Dubro 6oz tank, use the full length of the brass tubes. Push them into the stopper so about 3/4” protrudes into the tank. Bend the vent tube up so it just touches the top of the tank when the stopper is inserted. Then bend the fuel pickup tube downward slightly and trim the silicone tube so the clunk almost touches the lower back edge of the tank. Install the stopper and tighten the screw. Bend both tubes up so they will protrude from the fuselage just behind the firewall. You will need to cut a rectangular hole for them to poke through. Be careful not to kink the brass as you bend it.

Throttle Setup

Tip: When soldering flex cable, you will have a much easier time of it if you first dip the end you want to coat or solder to a clevis into some paste flux. I use the “greenless” flux used for sweat soldering copper water pipe together. It’s excellent stuff and can be purchased at most any hardware store where copper pipe is sold. You will get much better heat penetration, and it will suck the solder right into the parts.  

the servo pivot is at 1-3/4" from the front of the radio compartment and 3/4" from the right side of the fuse.

Okay,  that completes the two different versions of the plane and their unique method of construction. The rest of the instructions will be, unless noted, the same for both the electric and gas planes.

you can use poker type object to open a hole for the pushrod

Slide the pushrod tubes in

Stick them down with spray glue and tape

28. Cover the fuse with colored tape, starting on the bottom and working up the sides. It’s easier if the wing dowels are removed. I typically overlap the previous strip of tape about ½”. You may get more or less depending on the curve of the fuse or how you wrap edges. It’s not critical, just so all the foam is covered and the edges are stuck tight. Use some of the taping tips outlined in the wing building section, and you should be able to achieve a fairly smooth tape job. Be careful not to bend the back of the fuse when stretching the tape down the side as this could make aligning the tail section difficult. Cover over the tail slots, battery box (gas) or  speed control pocket (electric), and dowel holes as these can be cut away later with an X-acto knife or razor blade. When taping the pad that the horizontal tail glues onto, try to cover it cleanly with no wrinkles or tape bunching. You should have at least 3 layers of tape on the tail pad itself as we are going to use GOOP (E6000) to glue the tails on, and the GOOP will melt the foam under the tape if applied over only one layer of tape. It can be a little difficult taping where the pushrod tubes exit close to the tail, but I just cut several strips of tape and work them into and under where the tubes bend away from the fuse.

When taping the doublers, I always leave the tape long enough to go around the front of the doublers and into the engine compartment. Trim and miter the corners so they stick down nicely. If the tape bunches up a bit, pinch it together and use a scissors or razor blade to trim off the excess.

When you get to the top of the fuselage, push any excess tape into the radio compartment and trim the tape away from the servo pockets. I think it is helpful to have several layers of tape covering the top of the cabin to toughen up where the wing sits.

servos held in with black RTV Silicone, color doesn't matter - white or clear works just fine.

Finally, after the clevises are on and the controls are set up right, go ahead and put the servo arm screws on and tighten them down. DON’T FORGET--I’ve done that several times and the plane started doing very strange things--just before a crash!

Note we have changed the axel used on the Big T to 10-32 bolts with lock nuts. simple and works great.

Locate the 10-32 bolts and slide the wheels on them. Use the thin jamb nut to snug up the wheel on the bolt - not too tight. Then insert the bolt through the hole in the end of the landing gear and tighten it down with the serrated locking nut. We have found that this system is simple and you shouldn't have problems with wheel collars falling off and loosing a wheel in mid flight.

 The landing gear wood only fits on the fuselage one way. So situate it on the fuse then drill and bolt the landing gear in the center of the wood using the 4-40 screws and T-nuts. An 1/8” drill bit works well to make the holes. After the screws are tight, cut or break off the excess screw length. 

I recommend just taping the landing gear block in place with several strips of strapping tape, across the bottom of the fuselage and over the gear block, in front of the landing gear and several strips behind the landing gear. This will allow the gear to break loose in the event of a less than stellar landing. Bring a roll of tape to the flying field in case you need to reattach the landing gear. 

Use a piece of the colored tape to cover the strapping tape to make it blend into the fuselage.

Typical hookup for the Combo. This is showing how the speed control and servos hook into a typical micro receiver. In this case I am using a new Magnum receiver from FMA. We keep a supply of these and all crystals in stock. Your particular receiver may hook a little different so check your manual.

If you would like to add a fuse to any electric setup, this is a very simple way that uses two insulated automotive female spade plugs and a standard inline mini-fuse of the appropriate rating for the motor you are using.