PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
6.0 Subsystem Design-To Specifications
Author: Jarryd Allison
Co-Author: Brett Miller
6.1 Aerodynamics Design-To Specifications
Requirements for the aerodynamics subsystem were derived from customer requirements as well
as from the mission goals. The customer required that the aircraft take off in no more than 100 ft
and fly at conditions in a 5000 ft density altitude. Additionally, it was required that the minimum
wing span shall be no less than 5 ft and the airplane is required to be stable in both the
asymmetric and symmetric load cases.
Since the overall goal of the team is to win the competition, performance requirements were
derived from past competition winners. The aircraft was required to cruise at 100 ft/sec, stall at
40 ft/sec, and perform a 2 g maneuver at 80 ft/sec. Heuristic data is valid because performance
specifications such as cruise speed, and stall speed have not varied over the past years’
competition winners regardless of mission or overall aircraft configuration.
6.2 Missions Design-To Specifications
The design-to specifications for the Missions subsystem can be broken into three separate
elements: the wing mounted stores, the centerline store, and the aircraft container. Each of these
is vital to the mission of the aircraft and its performance at competition.
The design process includes an analysis of the loads acting on the stores, consideration of
multiple design alternatives, testing of those alternatives, an educated selection based on the test
results, and finally a successful implementation of the design choice.
6.2.1 Wing Mounted Store
Based on the sensitivity analysis, the loading of these stores will have a large effect on the
aircraft’s score at competition. This loading time factors into both the System Complexity
Factor score of the aircraft through its effect on assembly time, and wing store loading time
directly affects the score in Mission 3 (the heaviest weighted mission). It is therefore important
that the release mechanisms for these stores have the ability to load quickly. Although a specific
time requirement has not been established, multiple iterations should be utilized to achieve the
fastest loading design.
It is also important the store release when desired and not while in flight. To this end, the release
mechanism must release 95% of the time while being able to constrain the store under flight
conditions and loads. These flight conditions include a 3g force in the aircraft’s Z-axis and a
1.73 g lateral force. These design-to loads were determined from the following equations (which
in turn were derived using Error! Reference source not found.).
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