Extra 300 L 24% - 27%
Wing Assembly
1. Glue the 10mm x 20mm leading edge onto the wing. When it is dry, sand the balsa to match the profile.
Ailerons  
2. 2. Next, we need to cut out the aileron. You will have noticed by now that the surfaces in your kit have yet to be cut out. Look closely at one of the wing panels in the kit. You will notice that there is a line drawn on the wing, (usually on the top surface.) This is the line where the aileron will be separated.
In 24 % and 27 % the hinging is done slightly different than normal.(hinged the top of the wing) First, grab on of the wings, and look carefully for the line. On the top surface, go 4mm each side of this line, and mark a new line. On the bottom, mark 10mm each side of the line. If you want, join the lines from the top to the bottom on the side of the wing. This will help guide you when you cut the aileron out. Proceed to cut out the area between the lines. When viewed from the side of the wing, (i.e. the wing on a flat surface, and your eye at the same level as the wing, looking in at the tip), you will notice that you are cutting in the shape of an upside down 'V'. When you have cut it out, face the front of the aileron, and the back of the wing, with 4mm balsa. Also, face the sides of the ailerons, and the sides of the slot left in the wing with 2mm balsa. You should now not be able to see any of the foam you have just cut.
Each aileron will have 6-8 ¼ scale hinges, (Sullivan or DUBRO).
3. Now let us check the tube that holds the wing and the sleeve it comes with. First, let us try placing the sleeve inside the pre-cut hole in the side of the wings. You should make sure that the sleeve goes 2cm (3/4") beyond the half rib that is already placed in the wing.
4. Once It is done, cut the entire sleeve that sticks out of the side of the wing. Now glue this sleeve with epoxy and, in case needed, fill It in with micro balloons. This sleeve must have a perfect fit in the wing, as it will all that holds the wing to fuselage.
5. Fit the wings onto the fuselage, and check if they fit flush to the side. Sand very carefully until a perfect fit is obtained.
6. Once the sleeve has dried, we will start preparing the locating pins. First, place in position the wings main rib. Mark down on the foam the position of the locating pins and the screw that holds the wing. This screw should be placed somewhere along the wing and on the same line of the tube, so that when you place it, you actually get to screw the tube. Now drill on the foam the beds for the dowels of 12mm (1/2"). Glue and let dry.
7. Drill a 6mm diameter hole on the 12mm (1/2") dowels you have just glued. This will now be the beds for the anti torque pins. You can now glue them. For the screw that holds the wing, you must first drill inside the 12mm dowel just placed, a 4mm hole that will go all the way down and through the tube. Then thread the tube to place later the screw.
You should now try the wings and make sure they are squared. This means that the distance from the back of the fuselage to each wingtip must be the same. Once a perfect fit is obtained between the wing and the fuselage (step 7), and all is correctly squared, glue the main rib to the wing with epoxy.

8. Now glue inside of the fuselage the rest of the sleeve that will hold the tube inside the fuselage.
9. Now cut the holes for the servos in the wing. The size of the hole should be according to the size of the servos to be used. It is recommended to place two servos (with metal gears) of 4-6Kg or more on each wing half
Stab Assembly

1. Add the 10mm x 15mm leading edge to the stab.
2. Now the elevator needs to be cut off. This is done in a similar way as the wings.
In 24% and 27% there is a line marking the hinge line, like on the wings. Mark a line 4mm to both sides of this line on the top of stab. On the bottom, do the same, but 10mm away. Join these two lines on the side of the stab. This will help to guide you when you cut off the elevator. Now, you can cut off the area between the lines on the top of bottom of the stab. Note that the front of the elevator and the back of the stab will be sloped because of the way that the model is hinged. Now face the front of the elevator and back of the stab with 4mm balsa.
3. Face the sides of the elevators and stabs with 2mm balsa, again, like the wings.
4. Sand the stabs carefully to get a nice flush fit against the fuselage.
5. It's now time to repeat the same job you did with the dowels on the wing but now on the elevators, with the exception that in this case you don't need to place the 12mm 'bedding' for the anti torque pins. Just make the holes of 12 mm and that will do..
6. Check carefully the fit of the stab against the fuselage, and that it is all squared with the wings, before gluing the main rib on. Also, glue the sleeve for the tube inside the fuselage.
7. CAREFULLY AND ACCURATELY, cut out the side of the elevator, to give the rudder room to deflect. Make sure to give it enough room to deflect a large amount, but do not take off too much of the elevator.
8. Prepare the stab to fit 4 or 5 ¼ scale hinges, (DUBRO or SULLIVAN
9. Use a hobby knife to cut out the hole for your servos. The size depends on the servo that you will use. All the precautions used when cutting the aileron servo holes should be used here too. We recommend that you use a 4kg-6kg metal-geared servo

Rudder Assembly
Again, this is very similar to the wing and stab.
1.Glue the leading edge, which is made out of 15mmx10mm (5/8" x 3/8"). Do so with a good aliphatic resin.
2. Now, cut the moving part of the rudder. As in the wing and stabilizer, it is marked and you should cut leaving 8mm to each side of the marked line. Face the fin and rudder with 4mm balsa.
3. Now, glue to the top of the fin and the bottom of the balance of the rudder a 2mm balsa sheet (same as wings and stabilizer).
4. Prepare the rudder for 5 or 6 ¼-scale hinges.
5. Place the fin onto the fuselage, and once adjusted and squared, glue it with epoxy.
6. Next cut out of the balsa block provided to the shape of the rudder and start cutting it until you obtain a perfect fit both with the turtle deck and with the rudder. Actually, this step either can be done before or after the rudder has been glued.
Landing Gear
1. Mark the center of the landing gear plate in your fuselage, (part F23), and in the center of your landing gear.
2. Measure the distance from this line, to the front and back of the U/C.
3. Mark a line on the landing gear support from the centerline that you drew. This line should be the same length as the one you got earlier from the U/C center to the front and back.
Drill 3.5mm holes, and fit with screws.
Engine Box Assembly
1. Based on the engine you will use, carefully cut the plywood engine box. Be very careful when cutting this in order to keep the thrust line built into the kit Changing the incidence due to an inaccurate cut or measurement will surely change some flight characteristics of the plane.
2. Once the box has been adjusted, glue the F1 to the front of it.
3. Now reinforce the join between F1 and the sides of the engine box with triangles on the inside. Use epoxy glue for this. Now glue the top and bottom (F25 and F26) of the box. Let it dry.
Glue some fiber to reinforce the area, wrapping it around F1 and the box sides
Tail group
1. Due to the size of the tail group, you need to use some flying wires, connecting the stab to the fin and the fuselage under the stab. It is recommended to purpose designed wires, like the Dubro or Sullivan ones, fitting on the ends a 2-56 or 4/40 clevis. Remember to tighten these before a flying session.
2. Install the dowels

  • · Fin: As close as possible to the top of the fin.· Stab: Around the center.
  • Drill the dowel and place a metal support to adjust the clevis
Wheel pants
1. Glue some 3mm plywood to the inside of the wheel pants for reinforcement. Glue the two pieces together. Make sure to do this properly, to ensure that you get a nice result.
2. Sand the inside, to get a better joint for the reinforcement, expanding Cyano. Let it cure and glue using epoxy.
Align the wheel pants, and then drill a hole to screw the axle through the nut, and through the wheel pant mount. Use a 4/40 screw with a blind nut
Finish
You can now finish the model, by putting your radio gear, hinging, engine installation and covering. It is recommended to use an iron on film, due to its low weight compared to a painting.
Balancing your model
1. This must be done after completely finishing the model, with radio gear, tank, batteries, etc. (i.e. ready to fly, with no fuel in the tank.)
2. Move the batteries/radio gear around until you get the right CG. The CG on this model should be taken from the top surface of the wings, on the wing tube.
For the first few flights, use this balance point, and then you can adjust it to suit your own flying style.
Pre - flight

1. We think that you will find the Extra 300L as one of the best aerobatic models out there, and certainly one of the best models that you have ever owned. It has a very well thought out design, with no strange tendencies. The flight performance is excellent, at all speed ranges (Even very slow! J). Remember the Extra 300 is a giant scale, so whenever making descents put the throttle down to almost idle.
2. If you have followed the instructions carefully, taken your time, use the recommended CG, and 0 degrees incidence, you will get very safe flights, agile, and stable. Well, congratulations. You have finished your Extra 300L. We hope that you enjoy flying the model, and wish you years of success.

GOOD LUCK, AND HAPPY LANDINGS!!!!!

We wish the very best and hope you enjoy some superb flights!!!
Technical characteristics of the Extra 300-L

Escale
24%
27%

Wigspan
73''
82''

Fuselage
69''
78''

Engine
15 a 25 cm3
30 a 50 cm3

Weight

8/9 Lbs.
12/15 Lbs.