35% Extra 330S

Construction (Page 3)

 

 
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Engine and engine mount:
Once the bulk of the fuse construction was finished, I decided that now was the time to install the engine firewall. Installing the engine was pretty straight forward. The only thing that threw me off, was the incidences built into the fuse. In aerobatic type airplanes, the general rule is 0 degrees to the thrust line, although in this kit, the engine is set with 1 degree of down thrust. I figured that if it's built that way, then I will follow it, fly it, and if I don't agree, I will modify it later.
The fuse is built in such a way, that the actually firewall is tied into the whole shell. All you need to do is mark a pre-fitted 1/4" aircraft ply firewall, then epoxy it in. (I also used a little fiberglass tape inside the fuse to insure a strong bond)
     
Once the firewall was set, the next step was to make standoff's for the engine. I used hardwood dowel, and made 1" standoff's which pushed the engine forward enough to clear the front of the cowl.
Now that the motor was mounted, I decided to finish off the other small things related to the motor. I made a small plate out of 1/8" light ply to mount the ignition module on to. I will just Velcro the ignition pack in. The throttle servo is just mounted in a simple mount, with a plastic push rod, and the ignition switch is just mounted to a small plate on the side of the fuse. As far as mounting the cowl, I just drilled some holes all around, then glued in small pieces of wood with 4-40 blind-nuts. I then used some 4-40 button head screws to hold hold the cowl on. I'm trying to keep things simple and light in this plane.

Exhaust:
       
Here are a few pics of the exhaust set up. I originally had in mind to set up a tuned pipe system, but after thinking about it, I started to realize that all the effort of making tunnels, support shelves, etc, would just be a lot of work (and weight) For what I feel to be "not really worth it". I called my friend Jim Bisson from Bisson Custom Muffler, and he made up a set of cans to my specification. I have run cans similar to these in the past, and in all instances I found them to perform very well.
I also decided that the cowl opening was a little large and that cooling might be a problem for this motor. So I installed some baffling in the cowl to direct the air flow over the cooling fins of the motor. All that I used was some 1/32 ply.

 

Stabs and Wings:
Now that most of the major sections of the fuse are complete, I've decided to finish off the stabs and wings. Again, the stabs and wings come pre-sheeted, so what is remaining is to cut out your control surface, glue in the leading/trailing edges. Hinge, and bevel your hinge line. Cut out and install servos, push rods, etc.
       
As you can see in the pictures, I decided to double bevel the leading and trailing edges in order to achieve 3-D type throws. As far as hinging is concerned, I'm using plain CA hinges. Now I know there are many out there that will disagree with that, especially in a plane this size, but I've done it many times before of planes this size (even bigger), with no problems. I've also installed a servo box in the stab.  ZN line doesn't cut a servo hole for you in the stabs, and I'm assuming they leave it so that if you decide to install your servo in the fuse, you can. I on the other hand decided to install the servos in the stab, hence cutting and installing a servo box.
Here is a picture of the hinging process.

Once the servo is installed, I hook up all the linkages to the servo arms. As you can see by the picture, I'm using metal servo arms from Air Wild Hobbies, as well as Nelson Hobbies control horns (formerly Rocket City) This form of hook up is very common on giant scale airplanes, and works rather well. The process is simple, in that you hook up a ball link to the servo arm. Followed by a 4-40 threaded rod. I then make sure that my geometry is correct, and that the arm will be 90 degrees to the hinge line.
Once I mark that, I then use a piece of brass tube, sharpen the end of it, and slowly cut a hole through the Aileron/stab. Once that is cut, the next step is to epoxy a piece of wooden dowel through the hole you just made, drill and tap the dowel to accept an 8-32 screw, and voila....You have a control horn! (special note: For those of you not sure, the screw is screwed into from the top of the control surface, and then counter sunk as to keep it neat for covering and finishing.)
    Here are a few pics of the completed stab hook up, with all the linkages.
    Here are a few pics of the aileron setup as well. This is similar to the stabs, the only difference being that I'm using two servos per surface, which does take a little tinkering to line up, but once they are lined up will work in unison. The idea here is to use a Y harness to link the two servos to one channel, and have them working together.

Rudder:
   
As far as the rudder hook up is concerned, I decided to install the servo's in the back of the fuse. I was going to install the servo's in the fuse and use a pull pull system of some sort, but figured that It would be more positive to have the servos in the tail. By having the servo's in the tail, I'm now creating more of a push pull system. As you can see in the pictures the installation is fairly easy. I just cut out holes in the fuse, reinforced the holes with some 1/8 light ply frames on the inside, and installed push rods. Again I'm using Nelson Hobbies connectors (Rocket City) and a solid push rod on either side. (note: The push rod in the pictures are 4-40 steel rods, although I plan to use carbon fiber push rods from Central Hobbies. I'm just waiting for them to arrive and will install them once I get them)

 

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Last Updated 05/03/2007