THE Bucker Jungmeister is a high performance German advanced training biplane. One of these ships has been flown at the past two National Air Races by the Roumanian pilot, Alexander Papana, who has repeatedly shown its high maneuverability by flying across the airport upside down at altitudes of from ten to fifteen feet above the ground. Papana uses this ship for all high precision aerobatics for which he is well known. The Jungmeister lends itself very well for a flying scale model as it is well proportioned besides being of pleasing appearance.
The model described here is an exact flying scale model; that is, all the dimensions except the flying propeller are to scale. It is very unusual to find a model with a fuselage of this size that is not handicapped by an excessive wing span, small tail surfaces or a short landing gear.
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Just
like the full size plane in appearance;
it provides a real thrill when in flight
Fuselage
Medium balsa is used throughout except where otherwise noted. The main framework of the fuselage is constructed of 1/16" square balsa. Plates No. 1 and No. 3 should be cut out and joined so that the sides of the fuselage may be built over them. After the sides are completed, plates No. 2 and No. 4 should be joined so that the upper and lower cross pieces may be put in place. Note that toward the front the lower cross pieces do not lie directly under the upper ones. At stations No. 6, No. 7 and No. 8, the upper cross pieces are not placed between the longerons, but are lowered about 1/4" to allow the rubber motor to pass through. Next cut the bulkheads from 1/32" sheet balsa but do not notch them until they have been cemented in place. Bulkhead No. 9 is made of two pieces of 1/32" sheet balsa cemented together with their grain at right angles. The rear hook is attached to this bulkhead after which the hollowed out tail block is added. The stringers are 1/32" x 1/16" balsa.
The entire cowling and the upper part of the fuselage up to the rear of the cockpit is covered with 1/32" sheet balsa. This can be done easily by covering in sections between bulkheads being sure to get good joints. The sheet balsa should be well sanded; a coat of banana oil well rubbed in will aid in bending the wood. When the cowling is finished the nose block should be cut roughly to shape and cemented to bulkhead No. 1. It can then be finished to the exact shape shown in the drawings. The nose block may be left solid but be sure to drill the 3/8" hole for the nose plug. The nose plug, details of which are shown in plate No.1, should be made of hard wood if possible.
There is a single stringer on each side of the fuselage and one along the center of the bottom. These stringers are made of 1/16" sheet balsa tapered at the rear as shown in the top and side views.
The fuselage should next be covered except for the area over the center section on the bottom and a small area underneath the rear hook. Make the streamlined headrest of soft balsa hollowed out.
Wings
The wings are built in six sections; four outer panels and two center sections. They are of conventional construction. Thirty-eight regular ribs and three special ribs are required. The ribs are all cut from 1/32" sheet balsa. The lower center section takes the landing loads and is therefore covered with 1/32" sheet balsa except for the upper middle part into which the fuselage fits. The wings have an angle of incidence of two degrees. The upper and lower wing panels on each side are identical. When notching the ribs for the spars be sure to pin the ribs together so that you will have perfectly straight spars. The tips are of 1/32" square bamboo. All struts are of 1/8" x 1/16" balsa carefully streamlined.
The wing fillets are made of very soft balsa cut to fit over the top of the lower center section. They are placed snugly up against the side of the fuselage but cemented only to the center section. Finish them off smooth with fine sandpaper.
Cement small blocks of wood on the top or bottom of the spars where necessary at the strut points. The wires are of silk thread and consist of two landing wires, two flying wires and two diagonals between the outer struts on each side.
The landing gear consists of two main struts and five smaller struts of 1/8" x 1/16" hard balsa. The main struts are cut from 1/8" sheet balsa and are attached to the lower center section just outside the center ribs. The landing force is thus spread out over a very large area and no other shock absorbers are needed. Axles of .028" wire are attached to the lower part of the main struts and the smaller struts are added; 1-3/16" balsa wheels are used.
Tail Surfaces
The tail surfaces are constructed with spars and ribs of 1/16" square balsa. The outline of the rudder and the stabilizer tips are 1/32" square bamboo. After the leading and trailing edges are attached pieces of 1/32" x 1/16" balsa are added to the top and bottom of each rib and sanded down at the ends as shown in the detail drawing of the rib. This construction makes a very rigid tail surface that will not warp. The tail wheel and fork can be built from scrap wood. The wheel need not turn.
The propeller is cut from a block 3/4" x 1-1/4" x 8" and is of conventional shape. Six or eight strands of 1/8" flat rubber should be used. The stabilizer is set at one degree positive incidence. The rubber should be put into the fuselage by slipping it over a piece of 3/32" square balsa about 17" long and inserting it through the nose block.
The original model required a small amount of weight in the nose but if the nose block is left solid probably no weight will be required. The tabs will help for making minor adjustments. The model has shown itself to have a steep climb and a flat glide. R.O.G. flights of 30 seconds are made consistently. With the use of a winder, hand-launched flights of a minute or more can be attained.
