## This is a collection of tools and resources that we find ourselves using frequently.

## Weather Channel Weather Forecast

## Aviation Weather

## Unit Converter

## Standard Atmosphere Calculator

## Periodic Table of The Elements

## Wolfram Alpha Computational Knowledge Engine

## Wolfram Mathematica Online Integrator

## Material Property Data

## Stress Analysis Spreadsheets

## Engineer's Toolbox Analysis Spreadsheets

## Gasdynamics Shock-Expansion Calculator

## Airfoil data calculator (XFOIL)

Below is an example of using these tools. (Former) undergraduate junior Sumant Sharma used the Wolfram Computational Knowledge Engine site to solve a difficult problem in helicopter sling loads, and dynamic wind tunnel testing. When a load is suspended under a helicopter and the craft tries to fly fast, the load may go unstable, and experience large oscillations. Wind tunnel tests executed somewhere else, had shown a rectangular box load developing oscillations at very low speeds. When we tested a similar box in our large wind tunnel, it stayed absolutely stable. We were told that our results must be wrong, because the "(XXXXX) had had no trouble at all showing the oscillations developing".

Our students saw that the (XXXXX) wind tunnel was only as large as our smaller wind tunnel, and proceeded to test the same model there: sure enough, it developed oscillations at a low speed. We suspected that it had to be the effect of the walls of the tunnel, but how could we prove it? Computational fluid dynamics could do it at great expense, but showed little progress towards a solution. So the solution had to be simple to compute, and yet represent the fluid mechanics adequately.

Enter the Wolfram Knowledge Engine site: we found excellent tools there to simulate simple potential flow aerodynamics. Sumant used that to generate a case of a freestream, plus doublets to represent the flow around an object, and image doublets to represent the effects of the walls. See our paper at the ASME conference in Houston, November 2012, and the 69th American Helicopter Society Forum in Phoenix, Arizona, May 2013. We showed conclusively that in the proximity of walls, a combination of a symmetric pendulum swinging and a subharmonic, or out-of-phase, force such as that due to yaw oscillations, would grow in amplitude. The mystery was solved! A new technique to evaluate wall effects in dynamic testing came out of this exercise using undergraduate-level potential flow, and dynamics.