sim development plan

more useful output plots

calculate losses

annealing

modify guidance to permit 90 deg pitch

statistics and convergence plot on optimizer iterations

optimization:

look at Brent’s algorithm in Numerical Recipes for faster optimizer (re Ares I paper)

http://www.scipy-lectures.org/advanced/mathematical_optimization/index.html

https://en.wikipedia.org/wiki/Trajectory_optimization

faster compiler options, retry later

gcc -O6: 4.2 seconds

gcc -O2: 4.3

gcc -O3 -fomit-frame-pointer -march=native: 4.3

gcc -Ofast -fomit-frame-pointer -march=native: 4.2

1 sec faster with logging turned off

test different dt’s

validate sim using Vanguard data

publish Vanguard sim for PSAS

look at natronics

squawk: removing integrator settings in PBScript.xml causes change in apogee

if needed, use CEA to make map of engine Isp vs O/F or other parameters

ability to easily enter vehicle configuration

get faster desktop running

ability to run 2 or more vehicle configurations, compare results

modify trajectory.py to support alternate vehicle on the cmdline

use fuel fill level for pitch table index

capture tank pct-full at startup

cleanup PBScript, replace hokey simtime >= 150 check with arming. try delay

model development plan

try prepending custom hardcoded DOCTYPE to xml (loaded from PB.xml or Propulstion.xml) https://stackoverflow.com/questions/991864/creating-a-doctype-with-lxmls-etree/2858690#2858690

or try alternate xml parser https://stackoverflow.com/a/2155040

or try xmlproc DTD api https://stackoverflow.com/a/2148315

why is Paul’s burnout thrust lower than the model’s?

read http://www.public.iastate.edu/~aero311l/blowdown.pdf

read http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150015771.pdf

check on oscillations at staging

oscillates around +/- alpha. aerodynamically stable!?!

check on pressurant gas mass for fills: 40% 50% 75%

non-symmetric propellant depletion, will it cause excessive pitch/yaw during staging?

what is max allowed alpha*q?

check on symmetry of fuel vs oxi blowdown pressure curves. Paul says same pressure drops so mixture ratio won’t change

gamma for fuel pressurant. Paul says 1.4

check on flatness of Isp at low chamber pressure

yes, see CEA-runs/htp-kero.out 225 psi = 3080 m/s 99 psi = 3060 m/s 40 psi = 3040 m/s