Hi all,
Just started my Seagull Models YAK 54.
This is my first ARTF and also my first go at posting a construction project.
After lots of thought I decided on an OS 120 AX this seems to fit the bill as the model is designed for .91-125 motors, The 120 is the same size crankcase as the .91 so it was not a difficult decision.

First evenings work. After opening and inspecting the contents of the large box I decided to use the supplied hardware pack.
First mark and drill engine mount to suit the OS 120 ax keeping the motor as far back as possible without fouling the prop/spinner on the cowl, 130 mm from the bulk head to the front of the prop thruster is about right. Using the supplied bolts and washers bolt the motor to the mount and the mount to the bulkhead. ( when final fixing loctite nutloc will be used)
Next mark out and drill the cowl mounting screw holes (use the method in the instructions it works a treat).Fit the cowl and mark out for cooling/glowplug and muffler holes. Remove cowl and trim cowl I used a drill and a dremel type drum sander. You may want to wear a face mask as it gets dusty. Once all holes are all tidy refit cowl.
Follow instructions and fit tank hardware, the plastic pipe bends and sets after warming with a lighter! I like to use over-long fuel tube and push it through from the bulkhead, connect to the tank tube and pull back the tank with it once the tank is in position you can fix it with scrap balsa (even that is supplied).

Evening Two. Having never used CA hinges before I decided to give them a try, this after gluing one to some scrap balsa and trying to pull it apart! I followed the instructions but before gluing I marked the centre of each hinge, this makes sure you have the same amount of hinge on both sides of the joint. I glued in the ailerons first followed by the tail feathers, be careful not to glue the lower one until you install the horizontal stab and fin. I fitted the control horns before installing the fin and horizontal stab as it is easier to drill them flat. After removal of covering where the horizontal stab fits slide it in and centre it and check for square then mark covering film top and bottom, slide it out and remove film with a razor sharp knife, I cut shy of the line to ensure there were no gaps. When happy follow the same procedure for the fin. After checking all measurements mix up a generous amount of slow set epoxy and refit horizontal stab and fin check all is OK and leave overnight to set. I then set about the aileron servos, as the wires where not long enough I used extensions with heat shrink tube over the plug and socket.

Evening Three. Time to fit radio! Two Futaba digital servos for ailerons and the rest are Futaba 3001s a Futaba r1490p pcm receiver. 4.8 volt 2500 ma hour flight pack and heavy duty switch complete the radio, all fitted using manufactures instructions. Just a mention about the throttle linkage, because of the OS 120 AX the hole in the bulkhead is not usable; I re-drilled and used a snake type of pushrod. After all servos are installed cut to size the carbon pushrods and CA onto clevises, cut to length the horizontal stab brace wires and fit. Make up the closed loop wires and fit to servo.
The u/c simply bolts on as do the wheel pants and wheels. It’s now you remember to fit the tail wheel! Which is a nice item and I think works well.

I have just done a quick check of the CG position after fitting the alloy joiner and bolts for the wings and I think it is about right; I will have to get help to hold it as the balance is measured at the wing tip and my arms are not long enough! But it is approx one thirds of the wing at the root I can adjust the battery and the prop and spinner have to be fitted so I have room to play with.

I will post more info when I test fly, this will be around May because it is cold and wet here in the UK.Thanks for all your info and help with your posts and any info I can help with just Ask.
Rick.