= Earll Murman
{c}
<Earll Murman> is an <aerospace engineer> and MIT professor emeritus whose institutional profile identifies aircraft systems engineering among his specializations. His authored lecture on aircraft performance connects aerodynamic <forces>, propulsion, energy and maneuvering constraints. The lecture title page credits him directly and is dated 18 September 2003; the host course is a separate Fall 2004 offering.<Earll M. Murman by MIT AeroAstro>[Faculty heading and Specialization and Research Interests]{ref}<Introduction to Aircraft Performance and Static Stability by Earll Murman>[Title slide and Today's Topics]{ref}
\Image[https://aeroastro.mit.edu/wp-content/uploads/2021/09/headshot-faculty-murman_1-aspect-ratio-269-269-269x269-c-default.jpg]
{title=Earll Murman in the portrait provided by his official MIT AeroAstro faculty profile}
One useful connection in that lecture is <aircraft energy height>. For constant <mass> $m$, <gravitational acceleration> $g$, altitude $h$ and <true airspeed> $V$ in a still-air model, divide the sum of <gravitational potential energy> and <kinetic energy> by <gravitational weight>:
$$
H_e=h+\frac{V^2}{2g}.
$$
If <thrust> $T$ acts along the motion, <drag> $D$ opposes it, and other energy exchanges are neglected, the <specific excess power> is
$$
P_s=\frac{(T-D)V}{mg}=\frac{dh}{dt}+\frac Vg\frac{dV}{dt}.
$$
This expresses the possibility of using the available mechanical power for climbing, accelerating, or both.<Introduction to Aircraft Performance and Static Stability by Earll Murman>[PDF pp. 21–24, Specific Energy and Excess Power and Summary of Power Characteristics]{ref}
For an original stipulated example, take $m=1000\,\mathrm{kg}$, $g=9.81\,\mathrm{m/s^2}$, $V=50\,\mathrm{m/s}$ and $T-D=300\,\mathrm N$. Then \b[$P_s\simeq1.529\,\mathrm{m/s}$]. At constant <true airspeed>, that is the model's climb rate. At constant altitude, the same instantaneous power gives $dV/dt=0.30\,\mathrm{m/s^2}$. These are alternative allocations at the stipulated condition, not a claim that an actual engine maintains the same excess <thrust> throughout a maneuver.
The distinction illustrates why satisfying a <lift> or <aerodynamic load factor> requirement alone does not establish sustained performance. Measurements of speed change, altitude change, <thrust> and <drag> test different terms of the energy account. The lecture's force and energy models make those assumptions explicit; they do not replace configuration-specific experimental data.
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