Case Study $-$ Part $2$

This is an extension of Case Study Part $1.$ You will need the following from Part $1$:

$S_w=29\mathrm{.}5m^2,T_{\text{m}\text{a}\text{x}}=16000(N),C_{Do}=0\mathrm{.}02,K=0\mathrm{.}044.$

A spreadsheet will be helpful for some of the calculations. Assume steady level flight.

$1$ Following question $1($of Case Study Part $1),$ calculate the minimum thrust required and the speed for minimum thrust for the case of zero fuel load $($i$.$e$.,W=55,000N)$ at standard sea$-$level conditions.

$3263N,67\mathrm{.}2\frac{m}{s}$

$2$ Further to Case Study Part $1,$ plot $T($the thrust required$),\frac{C_L}{C_D}$ and $\frac{C_L^{\frac{1}{2}}}{C_D}$ against aircraft speed, $V,$ for the two cases of full and zero fuel loads. The two cases should be superimposed on single plots.

$3$ Calculate the density at which the maximum available thrust is equal to the minimum drag for the full$-$fuel$-$load case. Use the simplest assumption for the variation of engine thrust with density.

To what altitude does this correspond in the international standard atmosphere? $($Use property tables for the ISA.$)$

$0\mathrm{.}399\frac{kg}{m^3},10\mathrm{.}28(km)$

$4$ Further to question $3$ above, if one engine were to fail, what is the maximum altitude at full fuel weight $($i$.$e$.,$ ignore fuel consumed to get to the altitude$).$

$[4\mathrm{.}23$km$]$