Forerunner (oz6966)

About this Plan

Forerunner. Free flight duration model. Class A or 1/2A free-flighter with a laminar flow airfoil.

Quote: "The Forerunner. These pages were a pain to splice, nothing lined up. One wonders how these kids ever built from some of these mag plans. My guess is they took a few liberties when redrawing them! Thanks again David for supplying the scanned article!"

Quote: "Class A or 1/2A free-flight with a laminar flow airfoil. The Forerunner, by Paul E Del Gatto.

Ever since the advent of Carl Gold-berg's famous Zipper (oz387), there have been very few changes in contest free-flight model design. It is true that tail moment arms have increased and there has been a trend toward larger stabilizers; but these are minor changes, brought about gradually by revisions in the AMA rules and the greater amount of power found in today's engines.

But, during all this time, very little has been done in this country with respect to airfoil design. We are still using the same airfoil sections that we were using fifteen or more years ago, despite the fact that the airfoil section is of primary importance in determining the extent of a model airplane's success! There's nothing wrong with pylon type models employing conventional airfoil sections - but isn't it time for a lot less standardization of design and a little more originality, to obtain improved model designs?

The Forerunner is representative of some of our thoughts along free-flight lines. Into it we have incorporated what we feel is the most desirable force arrangement, without yielding to the pylon type of model. Contrary to popu-lar opinion, it is not essential to have a pylon to design a good contest model.

To the novice this departure from standardization would appear to be the most unusual feature about the design. However, those who possess a funda-mental knowledge of models will also note that the airfoil section is entirely different than what they have been using up to now.

Most airfoil sections adapted to model designs, with but few exceptions, have the highest point of the upper camber located somewhere between the 20% and the 40% station. However, with the P.D.G. 1608, the highest point of the upper camber is at the 60% station, as indicated by the "60" in the airfoil designation [The first number of the designation (1) is the series number, while the last (8) indicates the maxi-mum thickness, which is 8% of the chord].

The model climbs much faster than models of comparable size and power, indicating that it has a very low drag value. Further proof of the latter can be seen in the glide, which is unusually fast but with a very low rate of de-scent.

Models of this design have been pow-ered with engines from .039 to .090 dis-placement, though for contest flying at least an .049 is most desirable. With such a wide selection of engines to choose from,. chances are you have one on hand that you could utilize for this design. Now let's get down to building.

Construction: The plans are drawn half-scale and the rib templates and fuselage bulkheads are shown full size to minimize the problem of enlarging the plans. In designing the model's structure we tried to achieve what we felt was a satisfactory compromise be-tween streamlining, ruggedness and ease of construction.

Because of the liberal amount of balsa employed throughout, it is very easy to control the finished weight of the model through careful selection of the balsa used. The model shown weighs in at slightly less than seven ounces with an .065 Royal Spitfire; while another which went out of sight with an .049 OK Cub, weighed in at about five and a half ounces.

When constructing the wing, as always, care should be exercised in attaining the desired curvature. This is the primary reason for utilizing thin balsa sheet on the upper camber, extending to the point of maximum camber.

The fuselage is constructed entirely of sheet balsa, simplifying the job of getting the model completed. The notching of the fuselage sides at the bulkhead locations will assist you in obtaining a more accurate alignment..."

Supplementary file notes

Article.

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