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Back to overview: Preamble Exercises and Projects

`Chapter 10[pdf]:10.1 Introduction10.2 Stability of Aircraft Motion10.3 Flight Simulation for Design Assessment10.4 Building Aerodynamic Tables10.5 Applications Configuration Design and Flying Qualities`

Tutorial: Under construction.
Exercises and Projects – software here VLM, SU2
Review questions to consider before doing calculations

1. Explain why the CG must be ahead of the aerodynamic center for longitudinal stick-fixed stability. Give the definitions of the italicized terms.
1. What is tip stall? Why is it to be avoided, especially on swept wings?
1. The TCR computed below has, like the Concorde and many other high-speed craft, a highly swept inner wing leading edge. Thinking of low speed flight, what does it contribute? Can VLM model that?

Configuration computations

1. A balsa glider model. Proper flight simulation needs mass, CG location, and mass moments of inertia. The file glider.BMP  shows the scan of a balsa glider toy made from balsa sheet. balsa.txt holds the 3D coordinates of the outlines of the body and lifting surfaces in assembled form. The script `read_plot_balsa.m` reads the file and plots the outline of the polygons. The body is 3 mm and the lifting surfaces 1.5 mm thick. The units are m and the density of the balsawood is assumed to be 160 kg/m3. Your job is to compute the mass, CG and mass moments of inertia of the assembled model.  The function
`              `[iner,area,cg] = weibalpoly(xyz)``

computes inertia tensor iner around its CG, area area, and CG cg of a constant thickness plane surface bounded by the vertices in xyz.  Add up the contributions Volj, CGj, and Ij from the fuselages and wings:

`              Vol = sum(Volj);              CG = sum(Volj  CGj)/Vol              I     = sum {Ij + Volj [|CGj - CG|2 – (CGj-CG)(CGj-CG)T]}  ... (3)`

((3) is the “parallel axis theorem” of rigid body mechanics, look it up if unsure). Vectors are column vectors. There is a lead weight at the nose. What must it weigh to give pitch static margin 10% of main wing chord?  You may assume that AC is at wing quarterchord.

1. Compute the longitudinal stability margin at M 0.5 on the TCR by VLM. A sumo file TCR15.smx and a VLM geometry definition file TCR15.geo produced from it are provided. An octave script geo2table.m uses the `VLM_e.m` function to write a table (see Ch 3 exercises) of flight state parameters (Mach, alpha, beta, …) and force and moment coefficients.
1. HALEbook.smx and HALEbook.geo describe a typical High Altitude, Long Endurance configuration with no details of propulsion, fig. 1 below. Google the Airbus Zephyr to see an IRL example. Use the volume coefficient (see Ch. 10) to size the existing placeholder horizontal tail. The horizontal tail is all-moving around its quarter-chord line. The wing span is 30 (!) m,