June 20, 2010 in Many fuselage plans call for bends in the longerons, particularly around the nose area. If the curve is very slight, we can usually just flex the longeron into shape and pin it until the glue dries. But trying to do this with sharper curves puts stress on the airframe, and the fuselage may distort as the longerons strain to return to their natural shape. This week’s tip presents three ways to pre-shape curves into longerons permanently, to help you achieve tight bends without stressing your structures.
Setting a Curve With Steam
Gently bend the longeron while holding it over the spout of a steaming kettle, and it will hold the shape once removed. Check the curved piece against the plans and steam again as necessary.
Setting a Curve With Hot Water
Soak your longerons in hot water for a few hours and then pin them to the correct shape. When dry, they’ll be warped to the curve you desire.
Setting a Curve by Laminating
Carefully slice part of the longeron in half lengthwise. Start from the nearest end of the longeron and cut to the point where the curve will end (you’ll need a balsa stripper or a steady hand for this). Apply your favorite glue between the laminations, and pin the longeron to the correct shape.
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