535 - CG
- Hatz CB-1Establishing Center of Gravity Range
by Randy Brooks, NX24B "Bratz" CB-1 S/N535
The Hatz plans gives only the C.G. location as loaded. I established a C.G. Range for my Bratz CB-1 as follows:
The Clark "Y" airfoil is used on the Hatz with 50 inch chord. The center of pressure range is 18%
Forward and 35% Rearward or +9.0 inches and +17.5 inches from leading edge. Reference used is
Technical Manual T-400, Theory of Flight. I prefer to use 33% or +16.5 inches for aft center of pressure.
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Datum --- Lower wing leading edge
Forward C.G. --- +9.0 inches - 12.65 inches equals -3.65 inches
Rearward C.G. --- +16.5 inches - 12.65 inches equals +3.85 inches
Procedure to Use
CLICK HERE TO REFER TO SKETCH
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Calculate wing areas of upper & lower wings and add together.
Use lower wing leading edge as datum.
Divide upper wing area by total wing area equals 55% (approx.) of total
area.
Multiply the stagger (23") by 55 % equals -12.65 inches which locates
leading edge of the Mean Aerodynamic Chord (MAC) from lower wing leading edge (datum).
Forward C.G. equals 18% x 50 inches equals 9 inches aft of leading edge of MAC.
Rear C.G. equals 33% x 50 inches equals =16.5 inches aft of leading edge of MAC.
Locate forward C.G. in reference to (datum) lower wing leading edge.
9 inches - 12.65 inches equals -3.65 inches
Locate Rearward C.G. in reference to (datum) lower wing leading edge.
16.5 inches - 12.65 inches equals +3.85 inches
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535 - CG
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