PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
Table 18: Calculating the Load on Each Strut
Parameter Variable Value Units
Length from main gear to CG l m 4.00 inches
Length from nose gear to CG l n 7.50 inches
Takeoff Weight W to 14.00 lbs
Number of main gear struts n s 2 none
Load on the nose gear strut P n 4.87 lbs
Load on each main gear strut P m 4.57 lbs
Percent of takeoff weight carried by the nose gear %W n 34.78 %
Percent of takeoff weight carried by the main gear %W m 65.22 %
8.4.7 Main Gear Loading Analysis
The strength of the main gear for the Buff-2 Bomber was determined by analyzing both a beam
deflection and beam buckling case for the horizontal and vertical forces seen during landing.
These forces were due to the friction between the wheel and the landing strip (calculated with a
coefficient of friction 0.2 of to be 9lbs) and the impact force seen when the aircraft first touches
down (found to be 54lbs), as Figure 66 clarifies. Note that the main gear struts are angled at 80°,
increasing the overall length to 7.1 inches to preserve the 7 inches clearance of the aircraft. P N is
the impact load normal to the runway, and P S is the frictional load applied due to rolling friction.
This angle was done to extend the landing gear span while at the same time anchoring the gear to
a thick portion of the wing to prevent the structure from tearing out during landing.
Figure 66: Main Gear with Applied Loads
Figure 67 shows the beam deflection case Free Body Diagram (FBD).
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