This airplane comes with some very nice and lightweight phenolic control horns. They are designed as a two piece horn and the pushrod linkage is connected in between to ensure propoer alignment and eliminate the risk of wear or breakage due to any side load on the horn.

The slots for the horns are precut in the proper locations. All we have to do is locate the slots and cut them out. After the slots are cutout, place the horn in temporarily and mark the outline of the phenolic alignment plate. After marking remove the horn assembly and cut the covering away 1/8" inside the mark using an old soldering gun. You can use an X Acto knife, but you must be very careful to avoid cutting and weakening the balsa sheeting.

Once the covering is cut away use 30 minute epoxy mixed with milled fiberglass and install the horns.

Although at this point in the instruction manual the hinges have not been glued in permanantly yet, it is very important to ensure that the pivot point on the horn where the ball connector will be attached is centered directly over the center of the hinge line. Be sure to align properly and compare both elevators and ailerons and make sure the horns are aligned on the hinge line. You can see in the left pic just above that I compared the two sides to make sure not only that they were aligned on their respective hinge line but that the left and right are both in the exact same spot over the hinge line. If they are even slightly different you can end up with differential that will make it extremely difficult to match throws, especially on the elevators.

The rudder horn assembly is similar to the other control horns. As with any rudder horn assembly, it is very important to make sure that both sides are aligned directly over the hinge line and that the distance from the pivot point on the control horn to the hinge is exactly the same on both sides. This is to ensure that you do not have built in differential.

The Yak uses a standard Robart Hinge for all of the control surfaces. The airplane comes with all of the hinge points pre drilled and the hinges are temporarily set in place. All that is necessary for you to do is to lubricate the hinge before gluing and use either epoxy or an expanding glue like Pro Bond or Gorilla Glue to install the hinges.

One thing I did want to mention is that the horzontal stabs are small and the distance from the hingeline to the stab tube is shorter than the Robart hinge. So be sure to clip off the hinge so that it does not push into the stab tube.

The fuselage is a is a very lightweight, precision laser cut framed construction. I suppose I will mention the covering at this point. The covering is as nice as any I have seen. The scheme is beautiful and the covering was carefully installed. At a glance I can see no visible flaws or places that are loose.

The key features are the pre installed canopy latch that eliminates the need for hatch bolts and the general completeness. Also the fuselage is very large and roomy despite the very light weight. There is plenty of room to get your hands in there and work. Very nice.

Be sure to look the canopy over really closely. It is mentioned in the instruction manual and I found that there are a couple of place where the canopy is not attached to the formers, specifically the rearward canopy former. I used a thin bead of silicon to set the cowl in place where it was loose. I do not think I added anymore than 1/2 oz of weight.

At this point we might as well go ahead and install the stabs and get a look at the fit. As you can see below the stabs fit nicely on the provided carbon fiber stab tube. All we have to do is bolt the stabs in place with the provided hardware.

To install the stabs, slide the stab tube into place, lineup the alignment dowel and slide the stab into place. Using the provided hardware and a drop of blue Loctite on each bolt, bolt the stab into place. Thats it! Now lets move onto the landing gear and tailwheel.

The landing gear is a fairly simple straight forward installation. The landing gear block in the fuselage is supported by aluminum angle on either side. The bolt holes are predrilled in the landing gear, but you have to drill out the fuselage. Just be sure and line up the landing gear so that the bolt holes catch the aluminum angle brackets for maximum strength. Its really hard to miss, is you simply center the gear and use the landing gear as a drill guide you cannot miss.

The wheel pants need to be finsihed up as well. There is a light ply square that needs to be epoxied to the wheelpant so that the alignment bolts have something to bite into. The instructions call for simply screwing through the gear and into the wood but I opted to install blind nuts inside the wheel pant and use 2 4-40 socket head bolts to secure the gear. I have never had a wheel pant come loose using this t echnique.

The kit comes with the landing gear shafts, all you need to do is install the wheels according to the instructions. Be sure to grind off a flat spot for the wheel collar so that it does not come loose. I also used a drop of blue Loctite on the set screw.

The final step was to use a Dremel to grind out the pant so that it slips down over the shaft and then drill 2 4-40 holes through the landing gear and wheelpants, install the blind nuts (or screws) and secure the wheel pant in place. Done!!

The tailwheel is a nice lightweight carbon fiber design and is quick and easy to install.

All you have to do is drill for the tailwheel guidewire in the rudder 2" back from the hinge line, drill 2 1/16" holes for the tailwheel and screw it down into place with the provided hardware.

The only complication during this step was that the angle of the carbon fiber strut was a little steep and the guide wire did not line up with the brass guide in the rudder. I simply made a Z bend in the wire to get it lined up properly and the tailwheel installation was complete. Time to flip it over on its feet.

The upper left hand picture shows the design location of the tank. The front former gets in the way of getting the tank onto the front tray as illustrated in the picture so to rememdy this all that you need to do is cut the former just behind the tank away to match the width of the tank and slide it into place and mount to the tray. Thats it!

Now, I wanted the tank on the cg so that I would not get a cg shift as the tank emptied so I decided to do a modification to get the tank where the cg would remain constant.

What I did was cut out a slot out of the rear support ply of the landing gear mount just wide enough for the tank to slip through. Once I had the cutout where I wanted it I fiberglassed the seam of the horizontal and vertical plates and I was ready to install the tank as shown in the picture to the far right above. All of this is solid plywood so the structure should hold up just fine, time will tell. Again, this modification is not necessary nor is it suggested by Extreme Flight. The tank is very easy to install in the stock location and will work very well there. I only did this by choice so that the CG would remain constant as the tank level decreases through the flight.

Now, lets intall the engine!

The servo and linkage installation was a very straight forward process. All of the linkage hardware including pushrods, ball connectors and even the pull pull is provided for you. All you have to do is cutout the covering and seal the edges of the servo bays and install the servos. Once the servos are in place just connect the servos to the control horns and setup the linkages for the desired throw.

As you can see in the last picture, since I relocated the tank I used the tank tray as the location for the receiver and battery pack. I simply placed the receiver and battery packs in the necessary location to get the CG where I wanted it and used Fromeco velcro tie downs from www.fromeco.org. We are done!! Lets go take a few posing shots and give her a fly!