$1$ Using the data provided in Tutorial Set $3$:

i$)$ By plotting $C_D$ against $C_L^2,$ calculate $C_{D0}$ and $K$ in the relationship $C_D=C_{D0}+K{C}_L^2.$

$0\mathrm{.}009,0\mathrm{.}080$

ii$)$ Calculate the span efficiency factor $($Oswald factor$),e.$

$[0\mathrm{.}79$ or $0\mathrm{.}75$ depending on the method used$]$

iii$)$ Using $C_D=C_{Do}+K{C}_L^2$ show that $\frac{C_D}{C_L}$ is a minimum when $C_L=(\frac{C_{D0}}{K}{)}^{\frac{1}{2}}.$

Calculate, $C_L$ and $C_D$ using the values obtained in Question $1$i$).$

$0\mathrm{.}335,0\mathrm{.}018$

Case Study $-$ Part $1$

A twin$-$engine jet$-$propelled aeroplane has the following parameters:

Overall:

Wing span

Wing area

MTOW

Max. fuel weight

Aerodynamic:

$C_{Do},0\mathrm{.}02$

K $,0\mathrm{.}044$

Engine:

Max. thrust $($both engines$)$

Thrust coefficient

$16\mathrm{.}2m($not required in calculations$)$

$29\mathrm{.}5m^2$

$88,000N($i$.$e$.,$ including payload and fuel$)$

$33,000N$

$16,000N$ at sea level standard density.

fuel