If an aircraft takes-off with 10 % less fuel in -comparison to its standard configuration, how its range will vary.
If an aircraft takes-off with 10 % less fuel in -comparison to its standard configuration, how its range will vary.
Let the aircrafts fuel weight be ‘f’ and aircraft structural weight be ‘s’.The jet aircraft’s range is proportional to
\(\sqrt{s+f}-\sqrt{s}\)
Therefore fractional reduction in range is
\(\frac{\sqrt{s+f}-\sqrt{s+0.9f}}{\sqrt{s+f}-\sqrt{s}}\)
If \(f/s\sim 1 \)
\(\frac{\Delta R}{R}=\frac{\sqrt{2}-\sqrt{1.9f}}{\sqrt{2}-\sqrt{1}}
\\=8.6 \%\)
If \(f/s<<1\) using binomial expansion we find that \(\frac{\Delta R}{R}\) converges to 10 %.
For propeller aircraft the range is proportional to \(ln\left ( 1+\frac{f}{w} \right )\)
\(\frac{\Delta R}{R}=\frac{ln\left ( \frac{s+f}{s+0.9f} \right )}{ln\left ( \frac{s+f}{s} \right )}\)
If \(f/s\sim 1\) then reduction in range will be 7.4 %
If \(f/s\sim 0\) using series expansion for logarithm this converges to 10 %.
Therefore we see that in all these cases reduction in range is less than 10 %.