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Saturday, 2 May 2020

Slope TRACER Build




Slope Tracer Build Documentation 

By AREA17

This article has instructions both for the Slope Tracer and the Foam-board Spitfire.




Slope Tracer Build

The Slope Tracer is a great fun aerobatic slope plane. It can fly is a large range of wind conditions and with its EPP fuselage, it can take the rough and tumble.

Wingspan: 1300mm
Weight: 700-900 grams
Wing Loading: 11-14 oz/sqft  32-41 sq/dm
Airfoil: SD6060 mod tip
3 channel two ailerons and one Elevator (no rudder)
EPP Fuselage
Foam core balsa skin wings
Slope Soarer for Intermediate/Advanced  RC Pilots 
Suitable for light to strong winds (10knt-30knts)
Ballast can be adjusted
CoG 64mm from leading-edge

Supplied Tracer Parts

EPP CNC Fuselage
One Set White Foam Wing Cores
One set of Core Flute Tail and Fin
Canopy
Servo Mounts for TGY 9018mg

Needed:

*1.5mm Balsa Sheeting for wing 2x (1220x150x1.5)
* Balsa Aileron Stock 
* Balsa Leading Edge stock
* 3mmx1mmx750mm carbon strip
* Titebond   Original   *3m Super 77 Spray Adhesive
* 5 min Epoxy  
* Controls horns + Linkages 
* Masking tape   
*1600 Mah Nimh 4-5 cell battery (4.8/6v)
*Iron-on covering for both wings and fuselage
* 3 Mini Servo’s  min 2kg  *Servo Extension wires
* 3mm bamboo stick from tailplane, 1.3mm piano wire for canopy

Tools Required:

Sharp Knife, Sandpaper, Covering Iron


Step One: Prepare Fuselage

Cut out access bays for: Nose Weight, Battery, Cockpit, Servo Wires and Rear Servo

Use a sharp box cutter, a Dremel with a burr or a hot soldering iron to cut out access for the 90-gram nose weight (8mm each side), battery compartment (8mm each side), and cockpit(15mm each side). These are cut equal amounts on both the left and right-hand EPP fuselage sides. You can just use one side to cut access for wires and the rear elevator servo. (Wires holes about 4mm deep)
Note: You will need to find about 90 grams of lead to fit in the front cavity to ensure the CoG is in the ballpark.  We use a ladle and a blowtorch to melt lead into a useful shape, or you can just cut-up the lead sheet to suit. (25mmx 20mm x17mm thick).  Cut the slot in the fuselage for the bottom and top stiffening 3mm x 1mm carbon strip. The carbon strip can be glued in with CA. Make sure the flat side of the fuselage is flat to the bench while gluing to avoid a twist in the fuselage.





Step Two: Prepare wing

Prepare 1.5mm balsa skins, best to cut balsa proud with about 10-15mm overlap over the foam cores.
1220 mm x 150 mm balsa sheets are ideal as the length is about right with 30mm tip blocks
Join the left and right-hand foam cores and bottom jackets together with 3m Super 77 or 5-minute epoxy.
Use bottom foam jackets to reference cores… the wing should be flat on top.
Use your favourite method to attach skins, ie epoxy/ 3m77/ Titebond etc. We recommend either 3m 77 spray Adhesive or use Titebond Original. If using Titebond try applying glue to both the balsa and foam surface, let it dry for a few hours, position the skins on the foam, and use an iron/ covering iron to reactivate the glue. 
It's a  good idea to put the cores back in the jackets and apply some weights to the top. This should help keep the wings straight and true.



Step Three: Attaching leading and false trailing edges.

Glue the leading edge strip and a 1.5mm balsa cap on the trailing edge, use masking tape to hold in position until dry. ( Titebond or epoxy)




Step Four: Shaping Leading Edge and sanding trailing edge.

The leading edge needs to planed or sanded to shape, as a guideline the Leading Edge tapers from about 10mm and the root to 6mm at the tip. The profile gauges supplied should be used to check the correct shape.  Sand false trailing edge to the balsa skins. Glue tip blocks in place to give a wingspan of 1300mm. Shape tips.


Step Five: Shape Ailerons

The ailerons should be about 50mm at the root(220mm) and 28mm at the tip(120mm)
You can use 50mm aileron stock or use a suitable balsa block to shape. The Ailerons start 60mm out from the wing center. You can lightly tack or tape the stock to the false trailing edge to help with the shaping. Permanently glue the 120mm centerpiece.


Step Six: Fitting the wing servo's (mini servos such as HXT900, TRGY9018mg)

Start by cutting out the servo bays, these are 45mm squares at 90 deg to the aileron hinge line. They are positioned 92mm out from the centre line and 58mm from the false trailing edge. Fit the servo frame about 2mm below the balsa to ensure the cover is flush with the top. Pick out the foam within the servo frame, you should be able to see the servo wire conduit.
Make a penetration on top of the wings to exit servo wires.







Step Seven: Covering the Wing

This is where you need to decide on colours and what film. We find dark colours stand out and it's a good idea to have a contrast between the top and bottom.  The covering can also act as a hinge on the top and bottom.



Step Eight: Attach Wing, Fin and Tailplane

Score a line on the bottom of the coreflute tailplane 30mm back for the elevator. Use the top of the coreflute as a hinge.
Use epoxy to glue both the tailplane first then the fin, it's important to ensure the tailplane is to parallel with the wing and the fin is 90 deg. You should also check the distance from the wingtip to the tailplane tip to ensure both sides are the same. It's a good idea to insert a carbon rod (3mm) or bamboo stick through the tailplane about midpoint to help with stiffness.


You are now ready to glue the wing in position, you can use 5 min epoxy to give yourself some working time to ensure the wing is correctly positioned before the glue sets.  First, apply epoxy to the midsection only, position, and let set. The second step is to create a fillet where the wing meets the fuselage. This can be epoxy or silicon, use an icy-pole stick to create the fillet top and bottom.






Step Nine: Fitting the canopy

Trim the canopy to suit, we like painting the bottom of the canopy to match the fuselage profile, we mark the profile then using masking tape to cover the top of the canopy to profile line and paint the bottom.  We use a wire through the front of the fuselage to hold the canopy.





The finished Slope Tracer ready for balancing. (64mm from Leading Edge)


Step Ten: Control throws and flying

We recommend dual rates on all control surfaces. The Ailerons need some differential to give the best turning and roll performance, as guideline aileron 7mm up and5mm down. The Elevator needs 5mm up and down. These are good starting points, please tune as required.

Check the CoG 64mm back from leading-edge, check the lateral balance across the plane, charge the battery and go flying....


Enjoy

Andy and Richard