This experiment used hotwire anemometry to examine the von Kármán vortex street and how different surface conditions affect the wake profile of circular airfoils, or bluff bodies. Specifically, this experiment investigated how the various surface conditions affected the shedding frequency and Strouhal Number of the vortex street as Reynolds Number is increased. The cylinders tested varied diameter, surface finish, and wire wrapping. Larger diameters corresponded with lower shedding frequencies, rougher surfaces decreased Strouhal Number, and the addition of thick wires to the surface of the cylinder completely disrupted the vortex shedding to the point where there was almost no dominant shedding frequency. For the smallest diameter cylinder tested, secondary dominant frequencies were observed, suggesting harmonics.

To ensure safety is not precluded in the event of an engine failure, the FAA has

established climb gradient minimums enforced through Federal Regulations.

Furthermore, to ensure aircraft do not accidentally impact an obstacle on takeoff due to

insufficient climb performance, standard instrument departure procedures have their own

set of climb gradient minimums which are typically more than those set by Federal

Regulation. This inconsistency between climb gradient expectations creates an obstacle

clearance problem: while the aircraft has enough climb gradient in the engine inoperative

condition so that basic flight safety is not precluded, this climb gradient is often not

strong enough to overfly real obstacles; this implies that the pilot must abort the takeoff

flight path and reverse course back to the departure airport to perform an emergency

landing. One solution to this is to reduce the dispatch weight to ensure that the aircraft

retains enough climb performance in the engine inoperative condition, but this comes at

the cost of reduced per-flight profits.

An alternative solution to this problem is the extended second segment (E2S)

climb. Proposed by Bays & Halpin, they found that a C-130H gained additional obstacle

clearance performance through this simple operational change. A thorough investigation

into this technique was performed to see if this technique can be applied to commercial

aviation by using a model A320 and simulating multiple takeoff flight paths in either a

calm or constant wind condition. A comparison of takeoff flight profiles against real

world departure procedures shows that the E2S climb technique offers a clear obstacle

clearance advantage which a scheduled four-segment flight profile cannot provide.

There are many computer aided engineering tools and software used by aerospace engineers to design and predict specific parameters of an airplane. These tools help a design engineer predict and calculate such parameters such as lift, drag, pitching moment, takeoff range, maximum takeoff weight, maximum flight range and much more. However, there are very limited ways to predict and calculate the minimum control speeds of an airplane in engine inoperative flight. There are simple solutions, as well as complicated solutions, yet there is neither standard technique nor consistency throughout the aerospace industry. To further complicate this subject, airplane designers have the option of using an Automatic Thrust Control System (ATCS), which directly alters the minimum control speeds of an airplane.

This work addresses this issue with a tool used to predict and calculate the Minimum Control Speed on the Ground (VMCG) as well as the Minimum Control Airspeed (VMCA) of any existing or design-stage airplane. With simple line art of an airplane, a program called VORLAX is used to generate an aerodynamic database used to calculate the stability derivatives of an airplane. Using another program called Numerical Propulsion System Simulation (NPSS), a propulsion database is generated to use with the aerodynamic database to calculate both VMCG and VMCA.

This tool was tested using two airplanes, the Airbus A320 and the Lockheed Martin C130J-30 Super Hercules. The A320 does not use an Automatic Thrust Control System (ATCS), whereas the C130J-30 does use an ATCS. The tool was able to properly calculate and match known values of VMCG and VMCA for both of the airplanes. The fact that this tool was able to calculate the known values of VMCG and VMCA for both airplanes means that this tool would be able to predict the VMCG and VMCA of an airplane in the preliminary stages of design. This would allow design engineers the ability to use an Automatic Thrust Control System (ATCS) as part of the design of an airplane and still have the ability to predict the VMCG and VMCA of the airplane.