Homework #$2$

Design a small plane with:

Wing loading W$/$S$=20$lb$/$ft$2$ Power loading W$/$P$=20$lb$/$hp

Payload $200$lb Fuel burn $4$gal$/$hr $1$gal$=6$lb

Base drag coefficient cD$0=0\mathrm{.}02$ Aspect ratio A$=12$

Wing efficiency e$=0\mathrm{.}8$ Structure factor SF$=0\mathrm{.}6$

Prop efficiency $\backslash$eta $=0\mathrm{.}8$ Density $\backslash$rho $=0\mathrm{.}8$kg$/$m$3$

$1)$ The maximum cruise time is $4$hr $($no reserves$).$ For the given fuel burn, what is the total required fuel

weight in lb $?$

$2)$ What is the takeoff weight in lb $($structure $+$ max payload $+$ fuel$)?$ Take answer from $(1)$ for fuel

weight.

$3)$ What is the wing area in ft$2$ based on W$=740$lb $?$ What is the wing span in ft $?$

$4)$ What is the engine max power based on the power loading and W$=740$lb $?$

$5)$ For cruise at $80\%$ max power $($P$=29\mathrm{.}6$hp$),$ what is the max speed in kts $?$ This requires solution of a

cubic equation. You get two solutions. Take the larger number.

$6)$ For a cruise speed of $157$kts$,$ what are cL$,$ cD$,$ and cL$/$cD $?$ Compare cL$/$cD with maximum possible cL$/$cD$.$

$7)$ For a an airspeed of $100$kts$,$ a weight of $740$lb$,$ and at maximum power $($Pmax$=37$hp$),$ what is the climb

rate in ft$/$min $?$

$8)$ What is the minimum required thrust$-$to$-$weight ratio to sustain a $60$deg bank turn $?$

$9)$ The engine quits. What is the maximum possible glide distance in nautical miles from an altitude of

$9000$ft $?$

$10)$ Do a top$-$down and side$-$view hand$-$drawing of your airplane with dimensions