Messerschmitt M.20b
A simple and inexpensive sport scale model of a German 1930’s transport favorite!
By Chuck Felton PHOTOGRAPHY: CHUCK FELTON T
he Messerschmitt M.20b was a sin- gle-engine, 10-seat high-wing mono- plane passenger transport aircraft. It was designed and developed by Willy Messerschmitt in the late 1920s and early 1930s specifically for Lufthansa Air- lines for use throughout the 1930s on a vari- ety of routes. The fuselage was all metal, pro- viding a rectangular cross-section with seating for eight passengers with four square windows on each side. The single-axle main undercarriage was strutted vertically to the wing.
The aircraft made its maiden flight on February 26, 1928 but was lost when pilot Hans Hackmack bailed out at low altitude and was killed, after the surface stripped from part of the wing. The Lufthansa M.20s entered service in 1929 on routes that went from Switzerland via Germany to Holland and from Stuttgart via Marseille to Barcelona. From the mid-1930s, they were operating German internal and holiday routes. Two were still flying such routes in 1942.
The highly tapered wing embedded into
the top fuselage and large glazed wind- screen gives it an unmistakable appearance. And its boxy fuselage makes it a natural to
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model in corrugated board. Like the real air- plane, the model M.20b presented here is simple in construction and inexpensive as it uses 1⁄8-inch corrugated cardboard as the primary building material, which greatly re- duces both building time and cost. The design makes use of cardboard’s unique features in that it can be used in large sections and folded. For instance, each wing panel is built of a single piece of card- board scored and folded at the leading edge with cardboard ribs and a single balsa spar. The tail surfaces and fuselage are primarily cardboard with little internal bracing re- quired. The result is a low cost, fast building model that has good scale-like appearance and can take plenty of punishment at the flying field.
Cardboard varies in weight, but any 1⁄8- inch corrugated cardboard will do. Sources of this material include box manufacturers and local shopping centers where you can find stacks of discarded boxes. Look for card- board with brown paper on one side and a white finished Kraft paper on the other side. The white paper on the outside of the model results in a smoother finish and neater ap- pearance. The method of folding the card- board and the use of gummed paper tape to
AT A GLANCE Type:
Construction:
Wing span: Wing area: Length: Weight:
Wing loading: Line length/diameter:
C/L sport scale
cardboard with some balsa and ply
70 inches 503 sq. in. 43 inches 64 ounces
18.3 oz./sq.ft. 60 ft/.018 in.
Engine Required: .40–.50 two-stroke
seal the joints and exposed corrugations is explained in the construction hints. The model has a wing span of 70 inches and a length of 43 inches. The bottom of the airfoil is flat with a curved upper surface, due to the scoring and folding technique em- ployed. Engines of .40 to .50 size can be used. My model is powered by a .40 engine and has a fully fueled flying weight of 64 ounces. This weight combined with the 503 square inch wing area results in a wing loading of 18.3 ounces/square foot. Its size makes it a very stable sport flying model.
DECEMBER 2013
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