Harrier and Falcon build notes


  It's exciting to be at the start of a model's life, I thought it might be useful if I started to make some notes on my Harrier and Falcon builds.  I cannot claim to be the worlds greatest builder but I have made a few of these now.  The general construction of both models is very similar to the Willow 2 and SOR models.  There have been several improvements in model construction and design- speeding up the build and progressing the final model.  There are also a umber of different options available especially for aileron and flap controls, Flight tech sell one of many excellent LDS systems available if you do not want to follow the clevis and horns approach.


  The wing assembly is very straight forward.  The horns are supplied separately, this gives you the opportunity to use commercial LDS systems if you wish.  Zhou will now be supplying 8 clevises per model, this gives you the option to use the raised horns supplied with an LDS system if you wish.

  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 and their frames 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.



  The fuselage assembly has been made very straight forward thanks to the moulded tray.  This holds the servos, switch and ballast tube.  It does not arrive fixed, making the cuts for the fittings is 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 is wide enough to take 2 12mm servos (such as the King max 2035) side by side.  As the Falcon is narrower it is a much tighter fit, I managed to do this in my first Falcon but it was very tight.

  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 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 in the Harrier 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.

  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. 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.

Tungsten sources

Website: www.lyhpwm.com

Wechat: 15896504204



  These are still a work in progress and I will change them as I learn.  Especially with the aileron movement, these can be adjusted in flight with no danger.  Playing with the setting of both models it's fun to play around and see when the roll rate just doesn't get any faster.

                Aileron up 20mm down 12mm (at root) Flaps up 3mm down 2mm

                Flaps for breaks, over 45deg down slows her nicely

                Snap flap down 2mm across the wing

                Elevator up/down 6/7mm measured at the root.20% rudder mix is a help


CG 99mm


  The CG I have been using is 93mm 

 Aileron up 14mm down 8mm (at root) Flaps up 3mm down 2mm (more for throwing her around)

                Flaps for breaks, over 45deg down slows her nicely

                Snap flap, I have 2 setting I am playing with, either 2 or 3mm across the wing, both coming in during the second half of the elevator stick.

                Elevator up/down 4/5mm measured at the root. 15% rudder mix is a help

No comments:

Post a Comment