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Project Apollo - NASSP 6.4.3 released!
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Author Topic: Apollo 8 Beta Testing Bugs  (Read 19380 times)
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« Reply #210 on: February 17, 2017, 02:38:51 PM »

I had similarly large differences between conic and precision solutions when I'd do P37, though. AFAIK, the conic options just showed the relative feasibility of the solution when going strict Kepler, but you'd expect the precision solution to be more nuanced.

As far as I can tell, the SMa constraints are the only ones in erasable memory. I'm looking through the P37 assembly right now, but most of it is in interpreter pseudo-opcodes, which I may need to take a little time to figure out.
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« Reply #211 on: February 17, 2017, 02:50:19 PM »

For a normal return trajectory conic and precision phase are fairly close for MCC-7, so only two hours between MCC and EI. Direct Return Aborts have the greatest difference between conic and precision phase usually.

The orbit is fairly hyperbolic with a semi major axis of -118.2e6 meters and an eccentricity of 1.05. That might be the issue here. Different MA values give different results for the conic phase. I don't know why the Apollo 10+ values are any good, -118e6 as the semi-major axis (-236.4e6 as the major axis) should already violate the constraint. The Apollo 10+ constraint is about -69e6. So P37 would run into the MA constraint in any CMC version. The "70000E,E" value from the CMP Checklist should in theory allow the trajectory, the value is -268e6 there. But the major axis isn't directly used in the calculation as a constraint, it rather is used in a simple geometric equation that might not exactly make the specificed major axis a constraint.

I haven't found the exact reason for the failed iteration yet but it is probably caused by the hyberbolic orbit.
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