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convexengineering / SPaircraft

Models for commercial aircraft design
http://spaircraft.readthedocs.org
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CG Model/Fuselage Pitching Model #62

Closed mayork closed 7 years ago

mayork commented 7 years ago

For now this is just a discussion...

Berk I noticed that when running run_M072_737() and run_D8_eng_wing_opt() the HT of the 737 weight only 260 pounds while the D8 HT is about 900 pounds.

I found this very odd and think it could be due to either how we lump the CG calculation or perhaps fuselage pitching moment.

@1ozturkbe can you elaborate on how we handle fuselage pitching moment as well as how the CG is lumped?

1ozturkbe commented 7 years ago

I'd be very suspicious of saying it's because of lumping; it is likely due to any lack of consideration of fuselage pitching moment, which I don't know exactly how to model. I will take a look now and post updates here.

1ozturkbe commented 7 years ago

Btw, can you make a note every time you add a new aircraft model? It's really hard for me to keep track of the VSP stuff if in every pull there is a new model I don't know about. The code needs to be consistent all the way through.

1ozturkbe commented 7 years ago

Just so you know btw, I am working on the readthedocs branch (I messed up, and forgot to change over before making changes. ) Will let you know when I have something concrete.

1ozturkbe commented 7 years ago

D8_eng_wing is soooo wonky... It pretends like it as a 73 fuselage. That's the first issue... I will fix and let you know.

1ozturkbe commented 7 years ago

(this is exactly why you should get VSP working. you would have seen the issues right away :P)

1ozturkbe commented 7 years ago

I looked through the documentation and found the pitching moment relations. Added a template CM variable to D8_fuselage, but this is pending MTFLOW results.

1ozturkbe commented 7 years ago

@mayork just wanted to point you to this issue, so we can convince ourselves that the HTs were light to begin with...

mayork commented 7 years ago

i agree they always were light

mayork commented 7 years ago

CG model seems good. I'm closing. @1ozturkbe reel free to reopen if you see fit.