AttributeError when calculating fuel flow for A21N

[rmonstein]

Hi,

First off, thanks for the excellent package; much appreciated!

I'm using OpenAP with the integration in Traffic, and it works mostly fine. But I stumbled into something that looks like a bug. I get the following exception when trying to compute the fuel flow of a A21N:

----> 1 flight.fuelflow()

File ~/bla/.venv/lib/python3.11/site-packages/traffic/algorithms/openap.py:102, in OpenAP.fuelflow(self, initial_mass, typecode, engine)
     98     return self
    100 ac = openap.prop.aircraft(actype)
--> 102 update_mass = True
    104 if initial_mass is not None:
    105     if not isinstance(initial_mass, str):

File ~/bla/.venv/lib/python3.11/site-packages/openap/fuel.py:61, in FuelFlow.__init__(self, ac, eng, **kwargs)
     58 self.drag = self.Drag(ac, **kwargs)
     59 self.wrap = self.WRAP(ac, **kwargs)
---> 61 self.params = self.fuel_params()
     62 self.polyfuel = func_fuel(self.params["fuel_coef"])

File ~/bla/.venv/lib/python3.11/site-packages/openap/fuel.py:77, in FuelFlow.fuel_params(self)
     75 else:
     76     syno = fuel_synonym.query("orig==@self.ac")
---> 77     if self.use_synonym and syno.shape[0] > 0:
     78         ac = syno.new.iloc[0]
     79     else:

AttributeError: 'FuelFlow' object has no attribute 'use_synonym'

Debugging the file shows that I get a match for the synonym and syno has a value, but it seems that self.use_synonymis never assigned.

Would be nice if this could be fixed.