Question

What is the range formula for mixed power-plant?

(a) R=Emax\(\big[Π\frac{\eta}{C_P}+(1+Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4-1}\big\}\)lnω

(b) R=Emax\(\big[Π\frac{\eta}{C_P}+(1-Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4-1}\big\}\)lnω

(c) R=Emax\(\big[Π\frac{\eta}{C_P}+(1-Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4+1}\big\}\)lnω

(d) R=Emax\(\big[Π\frac{\eta}{C_P}+(1+Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4+1}\big\}\)lnω

The question was asked in an online quiz.

This question is from Cruising Performance topic in portion Cruising Performance of Aircraft Performance

Answer 1

Right answer is (c) R=Emax\(\big[Π\frac{\eta}{C_P}+(1-Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4+1}\big\}\)lnω

Easy explanation: The range formula for mixed power-plant is given by the equation R=Emax\(\big[Π\frac{\eta}{C_P}+(1-Π)\frac{uV_{md}}{C_T}\big]\big\{\frac{2u^2}{u^4+1}\big\}\)lnω where Π is the proportion of thrust derived from the shaft power in the overall thrust of the power-plant, CT, CP are the specific fuel consumption of thrust producing and power producing engines,  Emax is endurance and V is true airspeed.