Cermark F16 Propjet Build Log Page 2

Posted Tuesday, 12/2/2008

Covering Check

The F16 build is finally on its way. With all of the parts and accessories unpacked and laid out, I got started with a quick check of the assembly manual. First thing was to break out the sealing iron and take care of the few wrinkles and bubbles in the covering. The covering job done at the factory was very good by ARF standards, so little time was spent on this task.

Rudder and Aileron Hinging

Next up was hinging the ailerons and rudder. The elevator if a flying stab arrangement, so there’s no hinging here. Cermark provides CA fiber hinges which are frequently used. The instructions have you pierce the hinge with a T-pin to establish the recommended gap. I thought about using some Robart hinge points then dismissed the idea. The throws on this plane are fairly short and they will work fine. The ailerons, rudder, fin and wings come pre-slotted and fit is very good. The usual application of thin CA to wick it into the hinges was used.

F16-Build-Day-1/001-hinges.JPG F16-Build-Day-1/002-fin-hinges-ridder.JPG F16-Build-Day-1/003-hingedrudder.JPG

Fiber hinges with gap setting pins in place along with the vertical stabilizer and rudder before and after hinging operation. The hinging took all of 5 minutes.

Aileron Servo Mounts

Due to the thin wing and low profile Cermark wants to maintain, the aileron servos mount a bit differently than for a thicker more conventional wing. Here, the servo door is used as the mounting plate and rails with gussets were glued to the door. These are fabricated at the factory, so building them is not required. Medium CA was applied around the rails and gussets for a bit of additional strength.

F16-Build-Day-1/006-glued-rails-reinforced.JPG

Servo tray at left with its mounting plate and rails. At the right, both trays were treated to some extra medium CA to add strength.

Drill Those Rails

HiTec supplies a nice hardware kit with their servos. Eyelets, grommets and screws were all used as well as a single control arm. The HS-645MG is used for aileron control among other functions on this ship. Drill the locations where the servo screws will be placed. Using only the screw to tap the wood will most assuredly result in cracked and split rails. After drilling the holes, harden them with medium CA. This technique works well.

F16-Build-Day-1/007-drilled-servo-rails.JPG F16-Build-Day-1/008-servo-on-rails.JPG

F16-Build-Day-1/009-servos-in-rails.JPG

Servo mouting rails top left. HS-645MG Hitec servos will handle aileron operation. This is a high torque ball bearing metal geared analog servo.

No need spending more on digital servos. Although it had crossed my mind. The added feature of Hitec's digital 5000 and 7000 series servos is programability. Of course you need the programmer too.

Aileron Pushrods and Control Horns

The kit includes pushrods, clevises and control horns for the ailerons. The clevises and rods are history. They were replaced with 2-56 rods I cut and threaded myself. I am particular about how linkages go together on my planes. The supplied pushrods and clevises were sub-2-56 (metric) threaded rod on one end and nothing on the other. Cermark wants you to do a classic Z-bend at the servo horn; a technique I refuse to use on anything other than a .40 size trainer. A ball link will adorn the servo-end end of the rod that connects to the servo horn. Threading is required. The clevises are Sullivan Gold n’Rod with the snap clip to secure the pin.

F16-Build-Day-1/010-aileron-horns-pushrods.JPG

The control horns are pretty neat, but the pushrods had to go along with the clevises. Page 3 of the Build Log goes into what I did to change things a bit.

Go to Build Log page 3 HERE

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Rick Tressler - Columbus, Ohio

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