Question

if the % increase in power required for a helicopter to hover at an altitude above sea level is 6% higher that required to hover at sea level with the same figure of merit, determine the altitude. assume that the density change is 8% per km.

Answer 1

% power increase=6%

Let the power be x

New power =1.06x

$Density=\frac{mass}{volume}$

Mass=density*volume

$\frac{\dot{W_{sea}}}{\dot{W_{moun}}}=h\sqrt{\frac{\rho_{moun}}{\rho_{sea}}}$

$h=\frac{\dot{W_{sea}}}{\dot{W_{moun}}}*\frac{1}{\sqrt{\frac{\rho_{moun}}{\rho_{sea}}}}$

$h=1.06*\frac{1}{\sqrt{1.08}}$

$h=1.0200m$