PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
Figure 63: Landing Gear Placement
8.4.6 Longitudinal and Lateral Ground Stability:
Longitudinal stability is determined by the angle from the main gear to the aircraft center of
gravity as seen in Figure 64.
Figure 64: Longitudinal Stability
In order for stability to be assured, this angle must not be less than 15°, or else the plane will
tend to nose into the ground, prompting a propeller strike on landing or even during taxi. The
aircraft may also tip backwards under the same conditions, rendering ground control impossible.
With the current landing gear placement, the angle for the Buff-2 Bomber is 20°, giving the
vehicle ample stability in the longitudinal direction.
Lateral stability depends on the angle ψ which is seen in Figure 65. In order to be statically
stable (i.e. when not in motion) the angle ψ must be under 90°. Because the Buff-2 Bomber has
a lateral stability angle of 85° under the worst loading case (two rockets on one wing), the
aircraft achieves lateral stability in all circumstances (lateral stability was calculated using AAA
[27] ).
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