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USOFS question

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7:53 pm
May 19, 2010

KellyJ

Australia

Member

posts 15

Hi,

Just giving the usofs.py program a run, and wondering if someone could clarify what the variables are in the line below:

def __init__(self, t_B, T, m_E, m_F, m_P, A):

self.t_B = t_B

self.T = T

self.m_E = m_E

self.m_F = m_F

self.m_P = m_P

self.A = A

I am assuming that:

t_B = Burn time (s)

T = Thrust (lbf)

m_E = Empty mass (lb)

m_F = Fuel mass (lb)

m_P = Payload mass (lb)

A = Cross sectional area (ft^2)

Is this correct?

1:09 am
May 20, 2010

Luke Maurits

Adelaide, Australia

Admin

posts 1483

Your interpretation of all the variables is correct, but the units used are all SI units, so thrust is in Netwons, masses are in kilograms and areas are in square meters.

Btw, I suspect there is a flaw in USOFS's implementation of the RK integration algorithm. This occurred to me when I was writing AESAT. I'll try to fix this soon, since it's not something we want to forget about and leave in there! It's not a super serious flaw – it reduces the accuracy of the results somewhat but doesn't make USOFS produce entirely crazy results or anything like that.

Main CLLARE workgroups: Mission Planning, Navigation and Guidance. I do maths, physics, C, Python and Java.

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