Plan file details
Nordic Faun. A-2 sailplane model.
Quote: "A successful A-2 sailplane design that combines high performance with good looks. Nordic Faun, by J van Hattum.
THIS A/2 class model sailplane was designed in 1950 and first flew in the Dutch National Contests in 1951. There it showed considerable promise and was followed by a small batch of prototypes which confirmed this impression. The only modifications to the original design that proved desirable were a slightly larger fin and a change in the position of the tow-hook. Apart from this the model showed on tests that it was structurally and aerodynamically just about right.
The Faun is a logical development of the earlier and smaller Satyr (oz4564)
, a model of 60 inches span, published in the Model Aircraft Plans Series. By keeping the main proportions similar, it was possible to eliminate most of the snags that are met in a completely new prototype.
Structurally the fuselage is very much the same, except that a divided wing made it possible to obtain a cleaner top surface of the fuselage. The wing follows the same basic layout, but in the Faun it is in two halves with conventional tongue and box fixing, the box being built into the fuselage.
Owing to the relatively thin wing-section used, the wing-tongues had to be fairly short and narrow. This was the only detail that caused some apprehension and had to be proved in practice, but no trouble was experienced even when launching the model in a strong wind.
Generally speaking this model is a straightforward A/2 design. The fuselage construction employed caused favourable comments from the builders as it eliminates the usual worries caused by formers and stringers, is easily assembled, does not have to be trued up and has proved to be almost indestructible.
Fuselage: This is built with a flat base reinforced by stout longerons. On top of these are glued the vertical sides, formers serving as reinforcements. The recommended sequence of assembly is indicated on the drawing. If the builder has sufficient patience he is advised to make most of the parts required before assembly, as the work will then flow more smoothly. It should be superfluous to point out the necessity for cementing the fin absolutely true on the spine, as any assymmetry in this respect will lead to difficulties in flight.
Wing: The only elaborate details are found in the inboard section where the tongue is gripped between upper and lower spar, and in the dihedral joint where spars and nose sheeting should be well joined. It was found that the assembly of the inner portion and tip is most easily carried out when the three-ply dihedral braces are first glued alternately one to the inner and one to the outer panel. When assembling there will be less chance of the joint 'slipping' and thus affecting the dihedral angle. The wing covering can be of any light material the builder prefers - tissue, silk or nylon.
Tailplane: Construction is very similar to that of the wing, but with only one spar in the top surface of the section. Slight dihedral is incorporated in order to keep the tailplane off the ground when the model is at rest. This avoids strain and consequent distortion.
Flying: Check the model for possible faults in assembly, assymmetry and proper fixing. Place shot in the ballast-compartment so that the CG is at 50-55 per cent. of the main wing chord. Check difference in rigging angles as given on the drawing. Steam or dope out all warps in wing and tail-surface except for that required to obtain a slight turn. After a few hand-launches to check on reasonable longitu-dinal stability, tow the model up on a 50-foot line and observe its behaviour carefully. If it stalls, then decrease relative angle between wing and tail-plane and shift CG further back. Aim at a shallow dive after release, then increase difference of rigging angles a little (decrease angle of tailplane) and shift CG slightly forward. The model should then be just right.
A tip-up tail-plane D/T has proved successful on this model, but the deflection of the tail should be a good 60 degrees in order to avoid a tendency to execute a series of stalls, or even loops."
Nordic Faun, Model Aircraft, April 1952.
Direct submission to Outerzone.