Sparrow Hawk Part Three

I'm back for another round.

With the engine installed and the cowl cut and now fitting, its time to move onto the fuel tank. Having installed a Four Stroke engine, surprise surprise the tank supplied sits to high. This means that I'm going to have to do a bit of chopping about to get the tank in the correct position. I've also opted to fit a selc tank 

Marking the tank with a line, level with the fuel line I placed the tank inside the fuselage and moved it down until the line earlier marked lined up with the mixture screw on the carburettor of the engine. Once this was achieved I marked the the new position on the former F2 ready for cutting

 The picture opposite shows the hole enlarged ready to take the tank.

 As the tank practically sits  on the bottom of the fus and this being only balsa I decided to add a ply base to the existing balsa to give the base some more strength (we don't want that tank falling out now do we)

  And no I don't drink the mentholated spirits before any body asks.

Before inserting the tank I wanted to fit the onboard glow as far forward as possible. I  showed this magic little device in part one. As you can see, I have made use of some pipe lagging to house the battery and this was epoxied into place. The battery fits inside this very nicely I must say. You can also see in the picture that the indicator light and technical end have been housed in a balsa box. I have also soldered to extra leads to the battery terminals so that the battery can be charged without removing it form the plane.

The  tank is now placed into position making sure that everything fits and to give me an idea of how to route the throttle cable. As can be seen from the picture  below this turned out to be easier than expected just running down the side of the tank whilst being held in position with a small wooden bracket fixed to the side of the fus. 

This picture showing the throttle cable connecting to the carberrtor.

With the cable in place I next fitted the servo. This required the opening provided to be made a little larger (you would have thought by now, manufactures of these kits would have worked out a standard servo size).

Tea break time

As I have had trouble in the past with aircraft that have had servos in the rear of the plane to operate the elevators ( this causing radio interference due to the long lead run to the receiver) I  decided that I'm going to use a pushrod instead. This will also help in keeping the model scale like.

This also meant a further purchase from the model shop. A bag of 3mm push rods and length of dowel.

The elevators on the model are independent of each other and would have required two servos to operate them. This meant that the tail end of the pushrod would need to be split see picture below. This also meant that I would have to cut some new openings for these to exit from 

The next picture just shows the push rod from the other end.

What I haven't shown  you. To get the pushrod  down the length of the fus  I had to remove the covering from the bottom of the fus as the only way
to get it into position was to bend, pull through the formers with the use of both hands. Once in place I then recovered the bottom with profilm using the same methods as shown in part 1.

With the new pushrod in place it's time to install  the tail assembly (previously built ) to the fus. Before undertaking this operation, I was not convinced that the thin  fuselage sides where adequate to secure the tail assembly to,  being only 1/4 inch wide. I added two balsa braces one of which is also married up to the last former. See below

Once these had cured (30min epoxy) I then test fitted the tail assembly  making sure that it was all going to fit prior to gluing. This done I masked up all areas around the fus to avoid getting any unwanted glue on the model and commenced mixing a generous amount of 30min epoxy. This was then placed on both surfaces to be joined. Once the two parts had been married up and checked for alignment they where held in place with tape until cured and any excess epoxy removed with Mentholated spirit (told you I didn't drink the stuff)   

Just before these operations where carried out I fitted the tail wheel assembly that would later be linked up to the rudder.

           Time for more tea while it all dries

Wings

In part one I fitted the servos and glued in the ailerons. Before they are ready to be fitted to the fus they need to be joined together.

This is done the same way as I joined the stabilisers to the fin. An aluminium tube  fits into both  wing half's. This is glued  into the wing half's using 30min epoxy. The root ribs are also covered with epoxy and all is pushed together and held in place with the use of tape. As with the tail section every thing that I didn't want to get epoxy on was masked and Mentholated spirits used to wipe away any excess glue.    

Once the wing dried I then fitted the undercarriage and the spats. This was a very simple operation as the holes that locate the undercarriage at its various locations have all been pre drilled for you, the only thing you have to do is place on the saddle clamps and screw them into position.

As you can see the Profilm had lifted during the installation of the undercarriage and had to be re-ironed  into place.  Whilst carrying out this operation I went over the whole wing with the iron just to make sure that the covering was stuck secure to the wing.

With the tail section completely dry I moved back onto the fuselage and fitted the rudder servo and the closed loop system. The kit didn't supply a servo horn large enough for the system so I made one out of Prexlon  

With this made it was just a case of threading the cables down the pre-installed snake tubes and connecting the cables to both the rudder and servo horns.

With all that completed and the receiver and battery installed it was time to put her together and add the decals.

 Here she is finished, all that needs doing now is to balance her and range check the radio gear.

I will supply photos of her in the air after she has had her maiden flight.

Hope you've enjoyed following the build.

The next project on the cards is Brain Taylors plans for the De HAVILLAND MOSQUITO 1/7 Scale 81 inch wing span. so watch this space.

Thanks for reading