Fuel as an objective for the mission builder

[florentLutz]

Is your feature request related to a problem? Please describe. As of now, it looks like the only objective we can set for the mission computation is the range of the mission. This makes application like the computation of a payload range diagram or the study, for a constant MTOW, of a change in structural weight harder to conduct

Describe the solution you'd like Instead of having only the range as an attribute of the routes in the mission file, we could have an objective attribute that could be set either as a range or a fuel. In the latter case, the range would be computed so that the fuel consumed during the whole mission matched the objective fuel.

Describe alternatives you've considered The alternative considered so far is either to use Breguet equation where range and fuel can both be used as objectives but the formula lacks accuracy, or iterating on the range to get the right fuel consumption.

[christophe-david]

Interesting suggestion!

I have a question: as you know, our "complete" mission computation includes an assessment of the reserve by simulating a flight diversion. Such computation would make difficult to decide the fuel consumption objective needed for main route. We have the possibility to set reserve in much simpler ways, but then, either we do the same for all our computations or we accept to have some inconsistency between points of the payload-range diagram (but maybe that would be fine, at least for missions at MTOW). Another way of thinking would be to set a fuel consumption objective for the whole mission. I guess the cruise distance of the main route would still be the only driver, so that would be an ideal solution, but it would require a lot of rework.

What would be your opinion about that ?

[florentLutz]

I think it is important to keep the mission computation consistent so I would not opt for the first solution that involves a simpler way of computing the reserves. I was rather thinking about the second solution

[christophe-david]

I agree. But the concept of route was specifically designed for allowing to set a range for the "sum" of involved segments. By deciding there is one cruise segment, surrounded by climb/descent segments (but these can actually be any kind of segments), we just fit the cruise distance target to fit the given range. At the scale of the whole mission, there will be a need for user instructions about the segment target to modify among all available ones.