Project AMSO For Dummies v0.6

[Odahs]

I'm beginning to think there is something fundamentally wrong with the way LTMFD is working for me rather than anything specific in the guide.

Been through the scenarios and the guide many times now. Invariably it ends with an impact with the moon! Shame as I'm getting to point now of throwing in the towel as with so little experience of the programs I can't figure out what is going wrong.

Tried new clean installations of all the software and still getting some very odd numbers coming out and nowhere near getting a successful LOI burn. :hmm:

 

[Urwumpe]

Been through the scenarios and the guide many times now. Invariably it ends with an impact with the moon! Shame as I'm getting to point now of throwing in the towel as with so little experience of the programs I can't figure out what is going wrong.

What is the problem - if you impact on the moon, it is aiming perfectly...

 

[Odahs]

Wouldn't one expect a fly-by rather than an impact?

The problem is if I can get a calculation for the LOI burn (which I can't always) during its execution the CSM+LM impacts the lunar surface.

 

[Urwumpe]

Wouldn't one expect a fly-by rather than an impact?

The problem is if I can get a calculation for the LOI burn (which I can't always) during its execution the CSM+LM impacts the lunar surface.

I am not sure how LTMFD works, never used it yet. But I would expect it to calculate the navigation solution for the flight plan that you entered, so not paying attention to some small details could make you lithobrake, despite the MFD working correctly.

 

[Shifty]

I am not sure how LTMFD works, never used it yet. But I would expect it to calculate the navigation solution for the flight plan that you entered, so not paying attention to some small details could make you lithobrake, despite the MFD working correctly.

It should be working. LTMFD, from what I understand, is sort of a code branch of IMFD, both by jarmonik. LTMFD's integrations are optimized for the Earth-Moon system, and so, for me at least, produces more accurate results than IMFD does. Odahs is using the same settings I've been using to successfully calculate a lunar fly-by solution, but is getting impact instead of fly-by for some reason.

Odahs, can you post your Orbiter.cfg/orbiter_ng.cfg? Maybe there's a setting there that explains this.

 

[Odahs]

I've come across an old post that wasn't answered on the forum, stating that AMSO 1.21 was not working with LTMFD 1.4

So to set the scene, I've got a clean install of Orbiter 100830 with AMSO 1.21, LTMFD 1.4 and the Apollo 11 Sound pack.

The more I look at it, the more the numbers just don't add up. I'll set PeA to 111.1 for the TLLC yet achieve 300-400 which degrades to minus values by the time I get to the LOI burn time.

I ran through the TLI burn a few times and would get almost totally random values for the moon PeA in the thousands. Something is wrong somewhere!

orbiter.cfg

; === ORBITER Master Configuration File ===
EchoAllParams = FALSE
LPadRect = 321 0 865 574

; === Visual parameters ===
EnableCloudShadows = TRUE
EnableSpecularRipples = TRUE
EnableLocalLights = TRUE
AmbientLevel = 30

; === Physics engine ===
NonsphericalGravitySources = TRUE

; === Device settings ===
DeviceIndex = 4
ModeIndex = 18

; === Active plugin list ===
ACTIVE_MODULES
  OrbiterSound
  LunarTransferMFD
END_MODULES

orbiter_ng.cfg

; === ORBITER Master Configuration File ===
EchoAllParams = FALSE
LPadRect = 0 0 544 574

; === Device settings ===
DeviceIndex = 0
ModeIndex = 0
NoVSync = TRUE
WindowWidth = 400
WindowHeight = 300

---------- Post added at 03:40 PM ---------- Previous post was at 03:24 PM ----------

Here is a link to the old post:

http://orbiter-forum.com/showthread.php?p=419077

It is the last entry at the bottom of the thread

 

[jroly]

You could do another correction burn when you are closer to the moon. Use orbit MFD with ref Moon and see what the PeA is there then burn sideways until it is around 100km.

Also try changing the perimeters sections, I am not sure but you could try turning off/on some of the realism and Perturbation settings.

The translation you do for docking will change your PeA quite a bit.

That shouldn't affect it, even if the person flew all around the place, they would be on the same trajectory when they finally dock with the LEM because that hasn't moved.

 

[Shifty]

That shouldn't affect it, even if the person flew all around the place, they would be on the same trajectory when they finally dock with the LEM because that hasn't moved.

That's a good point, though you do translate the CSM+LM away from the booster after docking.

 

[Odahs]

The interesting thing about the perturbation settings is that the AMSO documentation states it is not 'sensitive' to these features - though I'm now wondering if LTMFD is so I'll try some different settings.

---------- Post added at 07:18 PM ---------- Previous post was at 10:14 AM ----------

:embarrassed:

I've figured it out - Oh my and they let me fly planes in the real world!

The problem was so stupidly simple I should have figured it long before.

LTMFD does not fix the units, so typing in 111.1 when it says something like 105.1 K results in 111.1 meters instead of 111.1 k

I sat down tonight determined to sort out the problem and the penny just dropped, I was hitting the moon during LOI because I was attempting the fly-by at 111.1 meters (this goes back right to the TLI burn) and not Kilometers. This is why I was seeing massive fluctuations after the docking maneuver and CSM+LM separation - the units were meters not kilometers, so naturally were all over the place.

I guess Shifty that's the trouble with a Dummies guide, you get a dummy like me trying to use it! I so, so appreciate the time and effort you have put in to try to help me out.

It's your call, but for a dummies guide perhaps it needs to be explicit to type 111.1k each time. Probably best to assume a dummy like me hasn't read the documentation for each of the pieces of software first.


I'm off..... .......to the moon... :facepalm:

 

[1987VCRProductions]

LTMFD works the best for these lunar missions. When entering orbital values, you need to add the units. You have to type in k for kilometers or M for "megameters" or no unit for just standard meters. I use these as a reference for the GET times, http://history.nasa.gov/SP-4029/Apollo_00g_Table_of_Contents.htm

The TOA field should be your PDI time so that your orbital path is going directly over the landing site at the time of PDI. On Apollo 11, the TOA should be halfway between the time of PDI and the time of Lunar Ascent. Mike didn't do a Plane Change burn and this compensation simulates that.

Consulting the original pre-flight press kits is also a good idea, it gives you an idea of how everything is supposed to work or tie together. In an effort to get the lunar burn times to match or to be relatively close to the historical GET times, you can play with your orbital period in lunar orbit.

 

[Odahs]

Finally completed a successful LOI burn

 

[jroly]

Unfortunately....Making those types of errors are part of the learning process :lol: :thumbup:

 

[Shifty]

Finally completed a successful LOI burn

Very nice. Believe me, I've made dumber mistakes. There's actually no consistency between MFDs there anyway; some default to km while others require the k.

 

[Odahs]

Very nice. Believe me, I've made dumber mistakes. There's actually no consistency between MFDs there anyway; some default to km while others require the k.

Yep it's something for me to watch out for. It's almost like a trap for any unwitting simmer used to using aircraft MFDs as *usually* one might expect a separate step to alter the units. Rather than it defaulting to a different unit than the one currently displayed.

I think the unfamiliarity of space flight was a factor too, whilst flying if a mega nav error is made I could pick it up quickly with cross references from other instruments. This is how I would spot doing something like entering 360 instead of 036 in the OBS for example. So I'll work on cross-references in Orbiter to check if things are reasonable which will help with situational awareness.

I now have a large note on my desk 'Don't forget to type K!' :thumbup: Similar to the one that tells me which way is 'up' and which way is 'down' on the RCS :rofl:

 

[Odahs]

The Dummy has landed

Even though it was all on AP the PDI and landing sequence was one of the most enjoyable sim experiences I've ever had, thanks for the guide Shifty, without it I would still be on the launch pad. :thumbup:

 

[Shifty]

The TOA field should be your PDI time so that your orbital path is going directly over the landing site at the time of PDI. On Apollo 11, the TOA should be halfway between the time of PDI and the time of Lunar Ascent. Mike didn't do a Plane Change burn and this compensation simulates that.

Great tip! For some reason, I'd always read TOA as "Time of Arrival". I'll be sure to include this in the guide. Did all of the other CM pilots do a plane change while the LMP and CDR were down on the surface? (Longer time on surface probably made it necessary.)

 

[1987VCRProductions]

The CMPs on Apollos 12-17 all did plane change burns while their friends were on the lunar surface. This was done so that their orbital plane was going directly over the landing site at the time of lunar lift off. Apollos 12 and 14 did it towards the end of the first EVA. The J missions, 15-17, did it a few hours before lunar lift off. There's an auto pilot in AMSO that aligns your orbital plane for you but I like to do these burns manually so that I can compensate for when lunar lift off will be. You can say that I lead the landing site like a hunter leads a flying duck, except the duck is stationary on the ground and the hunter is soaring through space at several kilometers a second.

---------- Post added at 09:06 PM ---------- Previous post was at 09:00 PM ----------

I have a YouTube Channel, I could make tutorials for each of the missions.

 

[Shifty]

There's an auto pilot in AMSO that aligns your orbital plane for you but I like to do these burns manually so that I can compensate for when lunar lift off will be. You can say that I lead the landing site like a hunter leads a flying duck, except the duck is stationary on the ground and the hunter is soaring through space at several kilometers a second.

Do you use Align Planes MFD for this; aligning for two or three orbits ahead?

Just wanted to say that your sound packs are fantastic! I'm especially looking forward to your Apollo 12: Conrad and Bean were such characters. Do you know if anyone's done the post-ascent sound for Apollo 11?

 

[1987VCRProductions]

I just use the standard map mfd. If the plane change is (x) amount of hours before the lunar liftoff, I go back and look at where the orbital plane is (x) hours before PDI. You can change how the map mfd displays your orbit. I think the setting that you want is orbit plane but I can't remember. I took some screenshots with my iPhone as a personal reference for each mission.

---------- Post added 08-05-14 at 12:48 AM ---------- Previous post was 08-04-14 at 10:21 PM ----------

Do you use Align Planes MFD for this; aligning for two or three orbits ahead?

Just wanted to say that your sound packs are fantastic! I'm especially looking forward to your Apollo 12: Conrad and Bean were such characters. Do you know if anyone's done the post-ascent sound for Apollo 11?

I forgot to answer the second part of your question. Mode1Bravo did a recovery soundpack for 11 that covers the reentry and recovery but I don't think that anyone has done anything covering LM Jet, TEI, or the journey home.

 

[RonDVouz]

This was absolutely the BEST tutorial for AMSO there is, explained in a way that made sense and is more adaptable than just the Apollo 11 mission it outlines.

In fact I spent all weekend playing it and changing the PeT arrival time, destination and MCC for each of the missions with an almost perfect result each time.

The only thing I think could use a tweak is when to use the autopilot circularization AP, but I hate it and it wastes a lot of fuel if you start it too early. In fact I just manually circularize my orbit (manually at perigee or re-entering the new orbit altitudes in the LTMFD LOI screen - BEST RESULTS!). Also the autopilot is a bit unpredictable, yesterday it gave me a "circular" orbit of 53km by 116km.