Pathfinder (oz8389)

About this Plan

Pathfinder. Free flight power model. Frog 500 shown.

Quote: "74in span, 88 sqare in wing area, low CLA design for all-weather contest flying, suitable for 5cc.

INFLUENCED by the sight of a high thrustline model climbing on a perfectly stable flight path despite a fierce wind, R. O'Nions was so impressed that he decided to build a similar model for his old Forster 29. The result was the prototype of the 'Pathfinder'.

Flight tests were perfect; turns could be made to right or left without fear of a spiral dive, and times right up to contest standard with frequent 3-1/2 to 4 minute durations off 15 second power run. Later a second model was built for the Frog 500, and various refinements added to make this one of the toughest and safest-to-fly designs available for 5 cc. In fact, the West Bromwich MACS have adopted the layout as a standard contest model, and in over 20 months' operation, only one crash has occurred. That was due to a displaced tailplane knocked out of true during take-off.

Structurally, it is an easy model to build, and we feel the wire brace wing fixing system will need no introduction to those who have used the same idea on the popular Quickie A/2 glider (oz3444). The two piece wing is also a great asset for transport, whilst the twin fins are detachable for easier packing. Another feature made possible by the low CLA design is the elimination of the normal undercarriage, replaced in this case by a pair of small 14 gauge wire skids

Construction starts with the fuselage. 1/4 sq sides are made over the plan with 1/16 sheet inset between formers 1-6. Assembly follows the order of: formers, spacers, engine bearers, gussets, wire parts, centre rib, then all of the 1/16 sheet, small soft blocks and 1 mm centre rib facings with stub dowels.

Wing construction needs little explanation; the mainspar should be added after the inner panels are Lifted from the plan, then the leading edge sheeting, after the outer panels are attached at correct dihedral. Wire parts should be especially well bound and cemented in place, then the centre section sheeted and ply facing ribs added. Tailplane and fins are straightforward, and when completed, the whole model should be covered with heavyweight Modelspan, well doped, and the fuselage given a coat of fuel proofer..."

Supplementary file notes

Article pages.

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