Willow 2 Build notes

A New Willow
  The New Willow 2’s has been designed to be simple and straightforward to build.  The principals are the same as with the Willow 1 and especially the Merlin model- as it’s also a canopy fuselage. 
  Here are a few of my notes on building the Willow 2.  

Wiring
  First things first and it’s time to get the Wiring loom made up.  This is very standard stuff, 4 * 1m servo extensions and a couple of 6 pin multiplex connectors do the job nicely.  T9 now has a purpose built Willow loom available.

Slots are already cut in the fuselage and wing to mount the connectors.  My preference is to open the hole up in the wing a little and leave the connector there loose.  I now favour having the Male part of the connector in the fuselage and the female loose in the wing.  Whilst assembling the Willow 2 I tend not to glue the fuselage connectors in until the ballast tube has been fitted and the wing servos fitted and tested.  If you leave a them hanging out loose you have room if there is a problem.

Fuselage and Servo Tray
  The Willow 2 does not come with a servo tray but making one out of Plywood and fitting it is a doddle.  The model’s large canopy is designed to help get the tray and ballast tube in and out easily for measuring and cutting.  The tray should accommodate the ballast tube, servos (Savox 255s are a good choice), switch and receiver.

  The ballast tube is included and a slot should be cut so that the tube sits on the servo tray rather than falls though it.


  Here with the receiver on top of the servo tray-

Tail-
  The Willow 2 and SOR only come with a 2 piece tail.  The fitting process is the same as with the Willow 1 and Merlin models- but the slim design means less space.

  The reduced space and thinner tail plane section means that the torque rods for the elevator should be made out of 2mm push rods.  Linking the torque rods to the snakes must be done carefully to ensure smooth and slop free elevator movement.  The shape of the torque rods is the same as for the Merlin (shown here).



  The link can be done with the ball links provided.  The back of the fuselage is tight and so the plastic ball links may need some sanding to allow for clearance.  If you do this I like to use a lock nut above and below the ball link.  These can be adjusted to help line up the connection height.

  An alternative connection method is shown here, using clevises.  More fiddly but kind of nice.

  At the front end it’s simply a case of fitting the clevises.  I am a fan of putting the clevis in the shortest hole of the servo arm possible.  The movement needed to generate the elevator movements you need is not that great.  Torque and servo resolution win for me.

Wing
  This last bit is certainly the easiest part of the build.  The horns which come with the Willow 2 can be fixed during manufacture or left for you to do.  I preffer to fit my own, this helps in the build as you can fit the connectors on the horns before gluing them in the wing and gives me control as to how flush I make them. (The horns show here are the right way up to go in the wing)

pic 9.JPG

  There is some filing to take away the wiper for each push rod and a hole in the subspar of each flap and aileron.  After few goes at dry fitting the completed assembly a good dollop of epoxy and micro fibres in the control will fix the horn securely.  If you tape the controls down to around 60 degrees the horns should sit nicely and be slightly visible over the remaining wiper.
  
A few pilots have told me that the small performance loss from fixing the horns so the clevises are proud of the wing is worth is fro ease of assembly and use- you decide it’s your model.

  Once set the horns will rub against the top of the wing skin, 5 mins with a needle file should relieve this and give you a flush smooth control.

With horns fitted it really is a just a case of gluing/fitting in the wing servos.

 As the controls are flush and the servo will use the nearest hole on the servo horn it’s important to make a slop free job.  I have now started to bridge the top and bottom skins with blue foam blocks at the side of the servo hatch.  This is very easy to do and reduces any wing skin flex in high winds- so I tell myself any way.

pic10a.JPG


  Although you can use HS85’s or a whole range of other servos, I preffer to use Airtonics/Sanwa 762 servos.  These have always proved to be very reliable and robust servos. 

Ballast and flying

  Ballasting a model is largely dependent on the conditions and type of flying you do.  I have 350mm of ballast cut into 10 equal pieces.  The ballast is made from 19mm B&Q chrome shower rail, cut up with a plumber's cutter.  This makes 1kg of ballast in the fuselage, almost the same can now ben fitted in the wing mounted tubes.  My latest SOR has turned out so light as a finished model that I have filled the wing joiner wth lead shot- to take the place of the ballast slug it seems to like so often.

  After sitting the sections of tube on a tile/heat proof surface, I fill the pieces with lead.  Usually twice to fill the bit of reduction from the lead cooling.  This is an easy job but it's probably best not to let the missus see you doing it on the new Hob (trust me I know).

  Set up is a very personal thing but a balance point of around 103mm is a good start.  I have started to put a little rudder mix into the ailerons for smooth and rounded turns.  But see what you think and how you like flying your Willow- I love flying mine!

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