build notes

    I designed the all my models models from a love of flying this type of model and as such I have built and flown several of each of these models over the last few years.  The aim of each design is to optimise the performance in the air and ease of use on the ground.  Materials, batteries and radio gear move on, the methods shown here are the ones that I do or have used on my own models over recent years.

  The build notes here are equally applicable for Saker, Harrier, Falcon and even Wyvern models.  There are clearly some differences in the models but the principals and approach suggested here will be a good starting point as you assemble your model.  There is no single way of assembling a model and you may feel that you have another- that you prefer.  If so- great and please share your ideas with the model flying community.

Wiring Loom

  I tend to make my own looms usually with 4x 1m servo extension leads.  This gives me with enough wiring and the servo ends I need, already fixed to the wires.  I used the Multiplex green 6 pin connectors, with the male half fixed in the fuselage and the female half loose in the wings.   Once soldered and tested I suggest some epoxy & microballoons or silicone over the connectors to make the loom more robust.  Once fitted in the fuselage there’s not much that can happen to your connectors.   As I leave the female connectors loose in the wing I add 5 cm of heat shrink over the wire and connectors for extra support. 

  Give yourself enough slack so that the looms in the wing stick out far enough to be able to connect the loom halves before the wings get too close to the fuselage- it’s just easier that way and there’s less chance of the ends being pushed into the wing

Wings

  The wing assembly is very straight forward.  The horns are supplied separately, this gives you the opportunity to use commercial LDS systems or the horns provided wish.  I generally use servorahmen LDS systems but The choice is yours.

  I have used King max servos for a number of years and for clevis systems or the smaller Falcon they have been excellent.  I not use KST and ChaServos for my larger models- to take advantage of their superior hold and torque.

  Regardless of the drive system used, I always ad a ply shearweb in the wing near where the servo arm will go.  The wings feel rigid and this may be over kill but for a small amount of effort I know when the controls are applied in the air, there will not be blow back.

Clevis method

  I have used 2 and 3mm clevises with the supplied horns in the past- they all work very well. I know that I am getting old in my build techniques.  If you use clevises rather than LDS, it is likely that you will need to grind some of the clevis off to help it move freely- this is normal.  Once the servos and horns are in place.  Measure the distance so that the push rods are made up to the correct length.

  Here's an illustration from my old Artist instructions, with a nice illustration of the geometry.  I grind the flap and aileron clevises.

  The hole I cut in the wing for the aileron servo horn.

The clevis and horn fitted, ready to clean the wing down, a neat and effective way to fit the wing out.  This is a Falcon wing, the Harrier wing is slightly deeper at the hinge so the horn can be more flush.  If there is any slop in your fit out, a drop of thick Cyano and kicker will fill the gap.

  The holes in the wing for servos have are large enough to help fit ball-raced servos frames.  I’ve used King Max servos for all my Harrier's and Falcon models.  The fit is excellent and the servos have proved to be fast, reliable and slop free, I’m really happy with the servos.  These can be bought in the UK or through Ali Express.

 The new Wyvern model uses 8.5mm servos in the Ailerons (10mm are possible but it's a squeeze)  The best 8mm servo I have found is the CHAservo HV85.  Solid as a rock and with ridiculous amounts of power.  

 LDS 

  I have started using LDS systems in all of my designs, the heavy duty (midi) LDS system from Servorahmen are good for almost all fit outs now.  I have used the Thomas Liu frames for some fit outs.  The quality of the Thomas Liu frames is excellent, they are a little more difficult to fit than the Servorahman but combined with the CHAservos they're a good combination.  

  Cutting the slot in the wiper can feel like a wide slot to cut out.  A little bit of tape to mark of how much to file away helps keep the wing skin neat.

  The LDS horn is long and means that you will end up cutting a slot in the flap sub-spar.  I tend to cut mine so the horn is pushed flush with the inside of the wing skin.  It's all a bit fiddly to get the horn in, attach push rod and make sure it's square and free, take it out and do it again with glue but it's worth it in the end.

 You can see that the horn and push rod have a top and bottom to get that pin as high as possible.

  A neat looking servo in situ.

  It's worth using as small a servo horn as you feel comfortable with.  Servos speed is never an issue these days but the extra hold and torque you get from a short servo arm is worth it.
  

Fuselage

  The fuselage assembly has been made very straight forward thanks to the moulded tray.  This holds the servos, switch and ballast tube.  The tray does not arrive fixed, making the cuts for the fittings very simple and safe away from the rest of the fuselage.  It also makes threading those servo wires much more straight forward.  

  The Harrier fuselage was wide enough to take 2 12mm servos  side by side.  Despite the shaping of the Saker and Wyvern, the shape of the fuselage is designed to allow 2 8mm servos and arms side by side. 

  The last Wyvern I built used the CHAservos HV85V servos, it's the speed and centring hold that makes a noticeable difference in the air.

  The Ballast tube will slide in place once the servo tray is fixed, it's important that you plan the model's CG and know where the middle of the ballast tube is before you start gluing things in.  The ballast tube is provided slightly over sized, this is easy to cut to size.  Gluing a piece of dowel in at the back of the tube is also a very simple process.

  I fix the ballast tube in place using epoxy and chopped mat.  I have found that I need to make a hole in the servo tray for the lock nut to recess into.  This does mean that the servo tray is taking the weight of the ballast on landing, so make sure you are happy with it's fixing

  A final and possible over kill is to fit a block of wood between the ballast tube and top of the fuselage.

  Like all the models I have worked on with Zhou, the ballast tube takes 19mm chrome shower rail perfectly.  This gives over 1.2kg of lead ballast and has always been more than enough, although I have used up to 1.8kg of tungsten on the bigger days- Ballistic!

  The back of the fuselage is fully enclosed.  Before starting to fit the tail, the 5mm carbon rods need to be fitted and fixed.  The easiest way to do this is to drill through the fuselage so that the 5mm rods span the rear of the fuselage, this is the recommended way and the strongest.  This makes for an excellent tail fix as well as adding further strength to the fuselage.

   Be careful not to snag the push rods with the 5mm tail joiners.  The snake should slide by nicely when everything is together but taking the rods out to have another go after you have glued them in is not easy.

  The tails come without the elevator horns fitted.  My recommended way to fit the tail horns is to use a piece of 2mm push rod, the last one I used was 12cm long, with about 2cm poking out of the tail root.  Bend the end that goes inside the elevator as shown as this gives a mechanical link to the elevator sub spar.

   Bend and tape the elevator open enough to expose the inside- you will be able to see the sub spar.  Make a hole in the sub spar and at the root of the elevator to let the elevator horn through.  Some epoxy and micro balloons dribbled in to the elevator will fix the horn in place nicely, I have started using laminating epoxy, as it runs nicely along the sub spar.  Don't worry if a little resin extends further down the elevator sub spar.

  In order to Make things easier I have started to trim away some of the wiper.  This certainly makes fitting the elevator horn much easier.  As the elevator movement is 6-7mm there s more than enough left.

  The connectors for the clevis are made from brass tube.  Flatten 1 end and make a hole for the clevis you are planning to use ( a 1.5mm drill bit works for a 2mm clevis).

   You can see where a slot has to be cut in the fuselage to allow the push rods into the fuselage. The back of the Harrier is a tight fit but full size clevises can fit.

 

  There is more room inn the Wyvern and Saker fuselage tails.  You can see where I opened up the back of the fuselage slightly for the clevises to move more freely.  This helps you to make the the copper rods a little longer and help the elevator gearing on you servos.

   The copper tubes are first glued and then crimped onto the steel rods.