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Piccolo plans are available from: Airborne Plans Service for AU$30.80 plus AU$2.00 P&H1.  
Plan No. 635
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A high wing sports/trainer that floats around the sky on low power but on full throttle becomes a very fast aerobatic hot rod.

Piccolo picture

by Bob Folie

Most budding aeromodellers dream of building a Spitfire or a Mustang as their first model. This is a bad mistake as these types of models are complex to build and tricky to fly.

But now we have the answer. The 'PICCOLO' - a model that is easy to construct, looks like the real thing, (maybe a CITABRIA or DECATHLON - both being aerobatic aircraft ) and flies like a trainer on low power. But when you put the pedal to the metal so to speak, it becomes very lively and aerobatic. So let's start building. I find it easier to cut out all components and put them in groups in preparation for assembly.

Fuselage

Piccolo picture

Select four sheets of soft 3mm balsa, 100mm x 900mm and lay 2 sheets edge to edge on a flat surface. While holding sheets tightly together run masking tape or similar along the join of sheets. Turn the sheets over then fold to open the gap between the sheets. Run a bead of glue along one edge then lay on a flat surface and scrape off the excess glue and leave to set. I find a slow cure CA type glue best for this purpose. Repeat the above steps for the other two sheets. When the glue has set, remove the tape from the sheets. You now have to carefully mark out the fuselage side outline onto the sheets and cut out both fuselage sides.

Lay both fuselage sides on a flat surface as a pair (both with inside facing up). Fit and glue fuselage doubler (D1) to the fuselage sides and hold flat with some weights (I have a big tin of lead sinkers for this purpose).

Fit and glue 5mm square balsa longerons to both fuselage sides then fit and glue balsa wing saddles (S) and tailplane saddles (D2) in position.

After the glue has set carefully mark the positions of all formers on the inside of both fuselage sides. I decided to deviate slightly from the plan here and used hardwood engine bearers instead of a radial mount. Cover the plan with Gladwrap or grease-proof paper to protect it. The engine bearers were then assembled into formers F1 and F2 together with the plywood engine mount brace and balsa tank floor (with the grain running across the bearers), using quick setting epoxy resin and checking alignment over the plan. When the epoxy has cured on this sub-assembly, the fuselage sides can now be glued into position using P.V.A. glue. Formers F3 and F4 and the wing plate P1 can now also be fitted.

Check the alignment over the plan and allow the glue to set. Next pull in the fuselage sides and glue in formers F5, F6, F7, and F8. I used rubber bands around the fuselage to hold formers in position until the glue dried. Again, check the alignment over the plan. Fit and glue the plywood undercarriage mounting plate P2 into position, then glue in 9.5mm balsa sheet to the fuselage bottom with the grain running across the fuselage.

Piccolo picture

Build up the front decking above the fuel tank with 6.5m soft balsa, then shape it accordingly. Fit a 6.5mm balsa sheet bottom between F1 and F2.

The engine can now be fitted to the bearers with bolts and blind nuts on the underside of the engine bearers making sure there is two degrees of right thrust. Alternatively, use a plywood wedge behind the radial mount to achieve the correct thrust lines. Bolt the engine mount onto F1. Next, glue on the 9.5mm side blocks, top and bottom blocks with triangular balsa along the corner joints.

Temporarily fit the propeller and the spinner, then trim the nose blocks to allow a 5mm gap between nose and spinner. The 3mm plywood nose ring can now be glued into position and centred on the spinner. Remove the engine and sand the nose to shape. Sheet the top of the rear fuselage between F4 and F7 with 2.5mm soft sheet with grain across the fuselage.

Tail Feathers

Using soft 9.5mm sheet cut all components for the tailplane, elevator, fin and rudder. With the protected plan on a flat building board start assembling firstly the tailplane, then the elevators either by pinning components or using weights to hold them in position. Glues can either be P.V.A. or CA types. Next, using the same method, assemble the fin and rudder over the plan. Fit and glue the fin to the tailplane making sure the tailplane is level and trailing edge is at right angles to the fuselage centreline.

Fit and glue the hardwood servo rails into the fuselage and brace ends with some balsa triangle.

The Wing

Piccolo picture

Lay the 6.5mm square spruce main spar on the protected plan wing half and hold with some pins or weights. Using a dihedral template fit and glue the centre rib W1 to the spar. Fit and glue remaining ribs W1, W2, and W3 to the spar over the plan making sure they sit at right angles to the plan. Fit and glue top 6.5mm square spruce mainspar to ribs and hold with weights. Fit and glue 6.5mm hard balsa aileron spar to ribs. Glue the 9.5mm hard balsa leading edge to ribs except for centre W1 rib.

Glue the trailing edge and outer leading edge gussets into the corners. Fit and glue 1.5mm medium balsa sheerwebs with vertical grain to mainspars between ribs W3. Glue the top 1.5mm soft balsa leading edge sheeting and glue the soft 1.5mm balsa trailing edge strip. Glue the soft 1.5mm balsa rib caps on ribs W3 and glue 1.5mm balsa sheet over the centre section. When the glue has set remove the wing half from the plan then repeat above steps for the other wing half.

Remove the joining piece between the front and back of ribs W1s and W2 to fit the dihedral brace D1. Fit and glue both wing halves together with dihedral braces D1 and D2 in position. Check for correct dihedral. Glue in gussets between W1 and D2.

Carefully fit and glue the leading edge soft 1/5mm balsa sheeting, checking to make sure the wing is true (no warps) and if necessary, adjust before the glue sets.

Cut out the lower section of the centre W1 rib to allow clearance for the aileron servo. Fit and glue 1.5mm soft balsa lower rib caps and lower centre section sheeting. Cut out a hole for the aileron servo and then fit and glue the laminated wing tips, sand them to shape and also sand the leading edge to shape.

The strip ailerons and wing centre section trailing edge are shaped from 9.5mm medium hard balsa sheet. When the correct airfoil shape has been attained cut the ailerons to length. The offcuts are used to fill the centre section of the wing. The centre pieces have to be grooved out to give clearance for aileron torsion rods.

The torsion rods should now be fitted to the trailing edge of the wing. Then glue in the aileron fillets checking that the torsion rods rotate smoothly without binding. Fit and glue 1.5mm plywood reinforcement plates to top surface of the wing.

The wing can now be trial fitted to the fuselage. Check to make sure the wing fits neatly into the fuselage and is correctly aligned with the tailplane. Hold in position with rubber bands or clamps. Drill through former F2 into the leading edge of the wing and insert locating dowels. Next drill two 4.5mm holes through the plywood reinforcement for the wing hold down bolts. Make sure the holes are at right angles to the wing top surface and go through wing bolt plate P1.

Now carefully open out the holes through the wing only to 6.5mm. With the aid of a tapered 1/4 Whitworth tap, a thread can be cut through the wing bolt plate to accommodate the wing bolts. After the thread has been cut, liberally coat the thread with CA glue to harden the thread. When the glue has set run the tap through the wings bolt plate again to clean the thread up. Remove the wing from the fuselage. Fit and glue the hardwood locating dowels into the leading edge of the wing.

Finishing Touches

Piccolo picture

Build up and shape the windscreen from 12.5mm soft balsa blocks. Shape and fit balsa block to centre of the wing front to blend in with the curvature of the windscreen. I used a commercial tailwheel assembly made and supplied by Radio Active. Rudder and elevators can be trial fitted. Temporarily fit the servos into the fuselage. Assemble and test fit the pushrods then install the throttle cable. Fit a 3mm ply servo tray to the wing.

With all of our construction completed give the complete model a light final sand. Completely fuel proof the engine bay and fuel tank area.

We can now apply our covering. I chose Solar Film because it is light and is easy to use. Make sure you follow the manufacturer's instructions. The windows were cut out of black contact vinyl and stuck in position.

For the sunbursts I used adhesive backed contact film as is used in covering books etc.

Refit ailerons, elevator and rudder gluing and pinning the hinges. Re-install the tank, engine and radio gear adjusting direction and amount of control throws as follows: Ailerons 5mm up, 5mm down, Rudder 18mm left, 18mm right, Elevator 15mm up, 15mm down.

Check the centre of gravity. I found the best spot was 78mm (3 inches) behind the leading edge of the main wing. To balance the model properly I fitted the battery under the tank.

Finally, check all systems. Range check with motor running then check all controls to ensure they operate correctly and in the right direction. Now out to the field for the real test.

Flying The Model

Piccolo picture

The trusty Magnum SE Pro 40 was fired up. Final preflight and range check done, power was increased and the Piccolo taxied out onto the strip. Ground handling was good and after a bit more power we had lift off.

After correcting a banking turn to the right and adjusting trims, we had straight and level flight (one day I'm going to have a model fly off the bench and fly straight and level first time).

Power was reduced to approximately half throttle and loops and rolls were completed without effort. On low power it floats around the sky but on full power it becomes a very fast aerobatic hot rod.

We used a Power Magnum Pro SE 40 in the prototype but a .25 motor would be ideal for a beginner.

All in all, it is a versatile first model trainer or a fun to fly sports model. I give it top score.



SPECIFICATIONS Piccolo

Type: High wing sports/trainer Wingspan: 1.35 metre Length: 1.15 metre Weight: 2.4kg Engine: .25-.40 4 channel radio control required



Piccolo plans are available from:
Airborne Plans Service
AU$30.80 plus AU$2.00 P&H1

Plan No. 635

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This page was last modified on the 21-May-02