This is the second post on Excel speed. The first part benchmarked the calculation speed of Excel 2003 versus Excel 2007 for various size arrays of formulas.

This post considers several aspects about improving the speed of spreadsheets in both MS Excel 2003 and 2007.

#### An Interactive Gated Ring Oscillator Tutorial – part #4

This is the fourth part of tutorial about making an interactive animated Excel model of a gated ring oscillator in MS Excel 2003.

#### An Interactive Gated Ring Oscillator Tutorial – part #3

This is the third part of tutorial about making an interactive animated Excel model of a gated ring oscillator in MS Excel 2003.

#### An Interactive Gated Ring Oscillator Tutorial – part #2

This is the second part of tutorial walking through the creation of an interactive animated Excel model of a gated ring oscillator in MS Excel 2003.

#### An Interactive Gated Ring Oscillator Tutorial – part #1

This is the first part of tutorial explaining how to make an interactive animated Excel model of a gated ring oscillator in MS Excel 2003.

#### A Delay Based Animated Excel Model for Single-Stage Logic Gates – part#2

This is the second half of the delay based Excel model tutorial. In this part the final formulas are derived and implemented in Excel 2003.

#### A Delay Based Animated Excel Model for Single-Stage Logic Gates – part#1

After learning how to model ideal logic gates in MS Excel 2003 it is time to attemp to create a delay based model.

#### An Animated Linear Feedback Shift Register (LFSR) as a Pseudo Random Pattern Generator in Excel 2003 – Part#3

This is the third part of a tutorial (1, 2, self) describing the creation of an animated Pseudo Random Number Generator model as a Fibonacci type Linear Feedback Shift Register in MS Excel 2003.

#### Building a game of Tetris #1– the generation and the rotation of the “tetrominoes”

This is the first section of a tutorial about the creation of a Tetris game in Excel using mainly spreadsheet formulas and very little VBA.

#### Longitudinal Aircraft Dynamics #11 – full 360 degree operation – aerobatics, inverted flight and loops – FINAL

This section updates an angle formula so that the virtual glider can now perform both backward and forward loops, as well as inverted flight.

#### Longitudinal Aircraft Dynamics #10 – implementing the numerical method

This section of the turorial finalizes the main dynamics calculations and implements the numerical method for approximating the glider trajectory. At this point, the model is already functional but with a crude interface.

#### Longitudinal Aircraft Dynamics #9 – more about forces and momenta – preliminary validation and testing

This tutorial finalizes the implementation of the forces and momenta acting on the plane. It also initiates some hand testing and validation of the overall dynamics of the plane.

#### Longitudinal Aircraft Dynamics #8 – worksheet implementation of the dynamics equations (c)

This section continues the worksheet implementation of the dynamics formulas for aerodynamic forces and momenta.

#### Longitudinal Aircraft Dynamics #7 – worksheet implementation of the dynamics equations (b)

This section continues the  worksheet implementation of the dynamics formulas.

#### Longitudinal Aircraft Dynamics #6 – worksheet implementation of the dynamics equations (a)

In this section, the parameters cl, cd and cm are scaled back to the force of lift, drag and the pitching moment of the aircraft. After that, the numerical  modeling scheme is described together with the macros behind it. At the end, the formulas for the angles of attack of the wing and the horizontal stabilizer are introduced.

#### Longitudinal Aircraft Dynamics #5 – finishing the aircraft

This section finalizes the aircraft (glider) by inserting the wing, the horizontal stabilizer and a center of gravity (CG) sprite in the layout.

#### Longitudinal Aircraft Dynamics #4 – virtual aircraft definition

This section of the tutorial explains how to create the  2D aircraft components for the animated longitudinal stability model. The first part deals with extracting the x-y coordinates for the fuselage, canopy, vertical stabilizer and rudder. The second part handles the main wing airfoil and the horizontal stabilizer airfoil. All thses parts will be put together in the next section.

#### Longitudinal Aircraft Dynamics #3 – layout parameters and wireframe fuselage generation

This section discusses the layout of the virtual plane and provides for the worksheet implementation of the plane dimensions as input parameters controlled by spin buttons and macros. In the final part a freeform is used to generate raw data for the fuselage.

#### Longitudinal Aircraft Dynamics #2 – 2D polynomial interpolation of parameters cl, cd and cm

In the previous section, the main wing airfoil and the horizontal stabilizer airfoil were simulated using Xflr5. The three coefficients, lift, drag and moment were then interpolated on charts in Excel using 4th and 5th order polynomials. This section shows a few tricks about how to easily introduce those 60 equations as spreadsheet formulas in Excel ranges. It also presents a simple linear interpolation method across the Reynolds number range. We need to do this since we simulated…