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Old 08-26-2017, 10:27 PM   #31

Hmm, so now you have:
- Only D3D9Client as active Module
- Done the changes in Earth.cfg
and still miss the ASDS?
But "10K to ISS" runs fine, right?

What scenario exactly are you flying?
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Old 08-26-2017, 11:08 PM   #32
Sailor Tim
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Formosat5 to Polar(VAFB ASDS EDL-only)
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Old 08-27-2017, 05:53 AM   #33
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Thanks Brian!

Verstuurd vanaf mijn ONEPLUS A3003 met Tapatalk
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Old 08-27-2017, 10:02 AM   #34

Voyager VI, many thanks for persisting with testing. I'm scratching my head over what's going on with this. Worth noting the Formosat-5 flight profile is steeper than all the others, so even less margin for error with ASDS location.

I tested the scenarios with Wind Effect on and off, but never tried turning off the Complex Flight Model or Non-spherical Gravity parameters - could that be the cause?
I'll check it out myself later.

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Old 08-27-2017, 11:25 AM   #35
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My two cents about the issue: it happened to me once while developing something I don't even remember now that, since some update code was in clbkPostStep and not in clbkPreStep, Earth was spinning and moving just a little (the amount relevant to time of the step) so I was missing the ground point for just that amount (that looks more or less what I saw in the picture).

could that be it?

Brian I read that you may have issues for landing on level above sea level, why don't you just attach the rocket to the ASDS? if it's close enough with right attitude etc,rocket creates attachment to asds and attach itself to it. Then you can even sail it home!


Last edited by fred18; 08-27-2017 at 11:27 AM.
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Old 08-27-2017, 12:34 PM   #36
Sailor Tim
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OK Brian, turning ON all Perturbations did the trick. Three tries, three perfect landings on ASDS.

Last edited by Voyager_VI; 08-27-2017 at 12:37 PM. Reason: Spelling
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Old 08-27-2017, 05:57 PM   #37

Hi Fred,
thanks for the input - I can see why you think it might be a sim-step/rotation issue. I certainly had to deal with that issue in the "Boostback" burn calculations. But I don't think it is that, in this case. I think I've narrowed it down to Wind Effect and Non-Spherical Gravity.

Re: Landing on ASDS - I had thought of going with an "attachment" solution, but I wanted to really test how well the 1st stage was landing, so I figured an "instant attachment" would be "cheating". But if the right velocity/attitude/pos constraints are met, then it can work OK. I like the idea of "sailing the ASDS home" - I hadn't thought about that - I will reconsider the "attachment" idea! Thanks!

@Voyager VI
I managed to reproduce the "landing short" by disabling both the Non-Spherical Gravity and Wind Effect parameters.

Disabling either one gives me a rather nasty (and unsurvivable) late Re-entry burn, but lands on target.

Disabling both gives me the "landing short" result.

What settings are you using for Non-Spherical Gravity and Wind Effect?
Does the landing work for you if Non-Spherical Gravity and Wind are on?

Guess I never did check the Formosat-5 scenario for Wind Effect discrepancies.

I'm going to need either a better "ASDS Location" calculation or a cleverer Re-entry burn algorithm. More tinkering required

---------- Post added at 05:57 PM ---------- Previous post was at 12:42 PM ----------

Thanks, Voyager VI. I think we tracked down the "anomaly".

The 1st Stage Re-entry burn on the EDL-Only flight profile is so finely balanced.
If the ASDS is a few km too far downrange, you never hit it.
ASDS too close, and you have to make the burn too high up and too early, it doesn't use as much fuel, not as much deceleration, further to fall, heavier stage, etc.

At the moment the Re-entry burn algorithm can correct for some cross-range error, but not down-range error. I'll have to work on it.

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Old 09-12-2017, 11:32 PM   #38

Update 170913 on OH:
Changed location of ASDS in scenario.
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