PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
The first flight of the aerodynamic prototype was a success. The pilot reported that the aircraft
was indeed stable, and the decision was made to remove the ballast to return the aircraft to its
normal static margin of 5%. A long ground roll was noticed on takeoff. This was attributed to an
analysis error made early on in the year. The relationship between the Cl in the takeoff distance
equation and aircraft incidence angle was not recognized, which resulted in a lower aircraft Cl
than predicted during initial analysis. To account for this lack of lift, an incidence angle of 5°
was added in order to increase the takeoff C L to 0.6 in order to make the 100 ft takeoff
requirement. More about this change can be found in section 8.1.3. Pictures from the first flight
are shown in Figure 122.
Figure 122: Pictures of Buff-2A flight test #1
13.2.2.2 Flight Test #2 and #4
The purpose of these flight tests were to gather more qualitative data on aircraft handling and to
accustom the pilot to the aircraft before riskier tests were undertaken. Both of these flight tests
had successful takeoffs and airborne maneuvering portions. However, both of these flight tests
ended with the nose gear breaking on landing. The main reason for the nose gear failure was that
the aircraft was designed to sustain normal main-gear-first landings of up to 4.0 g’s. However,
the nose gear was not designed to sustain the loads encountered by fast nose-gear-first landings.
The reason for the nose-gear-first landings was due to the pilot still getting accustomed to
landing the aircraft. The Buff-2 Bomber was designed with a relatively small wing and high stall
speed in order to reduce aircraft size, fit in the box, and reduces overall weight. However, these
design decisions indicate that the aircraft must land at a relatively high speed (25 mph when
empty) and the pilot needed some practice flying the aircraft in order to make purely main-gearfirst
landings. The nose gear failures that occurred during these two flight tests led to a redesign
of the nose gear shown in section 8.48. Pictures of the nose gear failure upon landing are shown
in Figure 123.
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