Rather than explaining what NotAeroCalc does, let me show you it in action.

You might have noticed a few things. First there is a need for * between quantity and its unit. I designed it this way because it simplifies the grammar. Another thing is that units are not pluralized, e.g. it is 32000 foot and not 32000 feet. If you need your answer in SI units just use expression in si.

In the backend I am using an amazing Python library called Astropy for conversion and Ply for parsing. You can use all the units available in Astropy, the list can be found here.

You can also use math constants like pi and e. Internally NotAeroCalc looks for unresolved names in math library in Python. So if you haven't created a pi variable, math.pi will be used.

Commands in NotAeroCalc

del x : deletes the variable named x if defined. If not defined ignores the command.

variables : lists all the variables defined in the current session.

Problem Solving with NotAeroCalc

Let's try to solve one problem using NotAeroCalc. Below is one of the homework problems from the course.

An aircraft flies at an altitude of 30,000 feet. 
Determine the air temperature (in [K]), 
air pressure (in [Pa]) and air density (in [kg/m3]) 
at this altitude, according to the standard atmosphere.

Following are the variables given.

g = 9.80665 * m/s/s
T0 = 15*Celsius in Kelvin
P0 = 1013.25 * hectopascal
h = 30000 * foot in m
a = -6.5 * Kelvin/km
rho0 = 1.225 * kg/m^3

Notice that some variables are given in m whereas others are in km. A good thing about using NotAeroCalc is that generally you do not need to worry about this discrepancy. However you can always use expr in si to have unified values.

Since 30,000 foot is in troposphere, we can use $ T_1 = T_0 + a*h $ formula to compute the temperature at 32000 foot.

Once we know the temperature, we can use the following formula to compute the air density.

$$ \frac{\rho_0}{\rho_1} = {\left( \frac{T_1}{T_0} \right)} ^{\frac{g}{R * a} - 1} $$

There are few things about ^ operator in NotAeroCalc that you should keep in mind.

• In a^b, b has to be unit less. So expression like 2^(3*m/(3*m)) is allowed, but 2^(3*m/3*m) is not, as it simplifies to 2^(1*m^2).
• By default the units are not simplified, you might have to use a^(b in si) if units in b cancel out.
• 2^((3*m)/(300*cm)) will give you an error. Use 2^((3*m)/(300*cm) in si) for now. I might fix this later.
• If a has units, b has to be like an integer. b = 3.0 is allowed, but b = 3.14 is not. So (3*m)^2.0 evaluates to 9*m^2.
• Finally, if a does not have units, any power is allowed.

In the above density formula, the exponent is actually unit less. So everything works out.

See the following recording for the whole solution.