Week 7 and 8 - 1/4 Scale Midget Mustang Build

Little progress was made during Week 7 (5 - 11 August 2007) due to work and family commitments so I've added week 7 and 6 together.

12 August 2007

I'm really surprised but after checking the CG with everything attached I discovered that the model is going to be tail heavy so I've moved the elevator servo forward - no pictures, I'm afraid.

(Above) The spat cut out for the wheel and ply side parts.

The spats took a lot of sanding and finishing but are now ready. I started them by sandwiching a sheet of 3mm balsa between two sheets of 12mm balsa and cut out the wheel semi-circle. Next I added the 2.5mm ply side plates and a 6mm sheet of balsa on the outside. On the inside of the spat I drilled the hole for the axle then held the U/C in place before drilling a hole through the U/C and inside of the spat.

(Above) The spat cut out for the wheel.

(Above) The finished spats.

I fitted a 3mm captive nut from the wheel side and bolted the U/C to the spat. I then glued a short piece of 5x5mm spruce to the ply either side of the U/C. Together this held the spat to the U/C leg, and stopped it from rotating. It also held the wheel in place as the outboard end of the axle is held in place in a matching hole in the outboard ply sheet.

(Above) The outside of a completed spat.

(Above) The inside of a completed spat showing the U/C mounting.

Once that was all in place I glued 6mm balsa around the hardwood strips before final shaping, fibreglassing and finishing. I was really surprised that the fibreglassing added only 3gram to each spat!

(Above) A spat mouted onto the U/C leg.

13 August 2007

(Above) An elevator half being fibreglassed from the centre.

I've fabricated and glued control horns to the rudder and fibreglassed the tail control surfaces.  I used cellulose thinners based sanding sealer to bond the glass cloth to the balsa and to seal the balsa. Two coats then I used the water based polyurethane.

(Above) The same elevator half with the glass cloth applied and two coats of sanding sealer.

(Above) The rudder after glassing and sanding sealer  - awaiting the polyurethane.

13 August 2007

(Above) An aileron servo mount plate with the fibreglass fairing added. .

I hate overly long aileron control horns that stick a long way out the bottom of the wing so, to keep them short I decided to cut slots into the wing underside behind the servo wells. To complement this I added fairings over the servo horn which now does not protrude above the surface. I cut a slot in the cover then added two layers of epoxy impregnated glass cloth over a layer of non-porous release film wrapped around a dowel. Once cured I applied the fibreglass, sanding sealer and polyurethane treatment described above.

(Above) The same aileron mount showing the fairing.

18 August 2007

(Above and below) The primed cowl.

Installed the flap servo mount and servo then tested the flaps and found that the geometry was wrong and they would not work smoothly. Ended up removing the horns and added new carbon fibre ones.   After this I primed the spinner and the cowl with 2-pack primer. The cowl needed another application of spot putty after spraying and a good sanding was needed thereafter.   (Above) The cowl showing the internal cooling duct.

(Above) The primed spinner.

19 August 2007

(Above) The finished spinner.

Sprayed the cowl, spats, spinner, wing and fuse today - a busy but productive day!

(Above and left) The finished cowl.

(Above) The spats still need the red flash added.     .

(Above) The sprayed wing, top view on left, underside on right.

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