Designing a balsa wood
glider is similar to designing a full-sized glider and applies many of the same
principles of flight. Specifically, the main design features the wing shape and
size, the wing placement and the overall tail size. Balsa wood or heavy oak
paper can be used. The balsa wood is heavier, so steps must be taken to conserve
the model's weight. Balsa wood holds its form better and is easier to build
parts with than paper. (See Reference )
Determine the wing shape and size. Use a simple rectangular shape for the
wing configuration to reduce calculations. The shape also is important in
determining the other dimensions to be designed for the glider.
Design the size of the horizontal stabilizer. Use the formula SH (the surface
area of the horizontal stabilizer in cm.sq.) = . S (the main wing surface area
in cm.sq.) times the chord length of the main wing in cm. divided by the DCG
(the distance from the center of gravity to the horizontal stabilizer). The
horizontal stabilizer is equal to the wing area times the chord and then divided
by the distance from the center of gravity times .. Plug your ideal numbers into
this formula. The tail will probably be too big. The way to fix this is to
reduce the wing chord and make the wings longer end to end to provide enough
surface area. Try several sizes and experiment on glider dimensions and how it
will appear when completed.
Design the vertical stabilizer. Use the equation SV = S times SP divided by
DCG multiplied by ., where S and DCG are the same as used in the above formula.
SP = the wing span and SV = surface area of vertical stabilizers. You have
calculated an area in cubic centimeters. Now convert that area to a nominal
length times width. These values for the vertical stabilizer should be
acceptable to the design.
Construct the glider using the values you have designed from the above
formulas. Use a pen to draw the wings and stabilizers on balsa sheeting. Cut
parts out from balsa sheeting.
Curve the wings slightly to take advantage of Bernoulli's principle of a lift
over a curved airfoil. Brace the wings in a curved position overnight. Place
curved wings on the top of the body, locating center of gravity so it is about a
quarter of the total wing chord in from the leading edge. Add a dihedral of -
degrees (wing ends are tipped up from body). Also, the wing angle of attack
should be set at degrees (pitched slightly forward). Glue wings to body in this
position. Set aside to dry.
Glue the vertical and horizontal stabilizers as calculated in your design to
the body. Mount these pieces flat without any up or down or right or left. Glue
and set aside to dry.
The more related article comes from http://www.balsafactory.com/.
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