Mid mission weight change

[Daniel E.]

How would I go about changing the weight of my vehicle mid-mission? For example a store separation problem. I attempted changing the analysis.extend line in the mission_setup but that didn't seem to propagate the weight change I wanted.

Thanks

- Daniel 

[Daniel E.]

Just to add to this, I have already setup 2 vehicle configurations. And I can run the base_mission with each configuration independently. But now I would like to change the vehicle configuration (weight and OML)  mid-mission as I am dropping a store. 

[Daniel E.]

Ive traced the issue to the way sequential_segments handles data. The way I see it, I have two options to change configuration mid-mission. I can do it mid-segment or between segments. 

Changing mid-segment involves creating a new mission type where store separation happens mid-segment. I'd have to figure out how to propogate the change to all the subdiscplines. 

If I change in-between segments, then I have to change how sequential_segments initializes. 

Does the SUAVE team have any thoughts on how to best handle this?

[Emilio]

Hi Daniel,

Your vehicle is definitely atypical. This isn't a bug. However, it's pretty easy to get around. You can hack SUAVE to do this without changing the source.

You can add a function to your script and have the mission call that function instead. Here's the function:

def initialize_weights(segment):

    m_initial = segment.analyses.weights.vehicle.mass_properties.takeoff

    segment.state.conditions.weights.total_mass[:,:] = m_initial

When you setup your mission just add this line to the segment you want the weight to change at:

segment.process.iterate.initials.weight = initialize_weights

-Emilio

[Daniel E.]

Thanks for the response. 

What about to propagate the OML change? Id like to take into account the difference in drag. 

[Emilio]

Even easier. When you setup the mission select the set of analyses that corresponds to the config.

-Emilio

[Daniel E.]

Via this line, correct?

segment.analyses.extend(analyses[tag])

[Emilio]

Yes

[Daniel E.]

Worked like a charm! Thanks