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Old 11-19-2018, 09:47 PM   #16
potjoe
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Wow it looks great ! 2.75 radii, what does it stand for ? How do I translate it into orbiter friendly datas ?

I didn't know actually, thanks a lot ! I've looked at the source code, but i'm quite a newbie in programming so I haven't find the values your mentionning, such as the timestamps... Where do I have to look actually ?

Finally, if i'm not mistaken, it does not give me any inclination right ? Or maybe i'm not looking at the right place.
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Old 11-20-2018, 06:51 AM   #17
Tommy
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 But... Here come the troubles. Even if I manage to set up the burn and eject correctly according to TransX plan, things will move a lot during the trip to Venus. And even if TransX tells me that I'm right on plan, IMFD's Map program seems to disagree. In this thread, you briefly explained the method Tommy :
TransX uses two-body solution in in calculations, so only a single, dominant body is considered, and different stages use the body appropriate for that stage. During your transit from Earth to Venus, only the sun is considered. IMFD's Map uses multi-body solutions and is more accurate. Have the numbers for the swing-by written down and use IMFD's Delta-V program linked with IMFD's Map (in Plan mode) to make the MCC's.
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But precisely : how can I take advantage of IMFD's Map program if I don't know the correct values for PeD, Pe MJD, Rin, etc.... ? This is really what is confusing for me and I don't understand what you had in mind. How to set up one ejection burn which will take me to Venus with almost no MCCs, matching the TransX plan even if its inaccuracy may tell me i'm not on the good trajectory ?
You get the correct values from Trans-X, and use them in IMFD's Course program (use Off-axis transfer mode). You will need at least one MCC, which can be made quite early, to correct the Distance and Inclination. This is easiest done as outlined above, with Delta-V, or it can be done using Target Offsetting in the Course Program. Try both, chances are you will find one easier. For me, that's Delta-V, but you may find otherwise.
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Old 11-20-2018, 09:28 AM   #18
Marijn
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Originally Posted by potjoe View Post
 Wow it looks great ! 2.75 radii, what does it stand for ? How do I translate it into orbiter friendly datas ?
2.75 radii would mean 2.75 * Venus mean radius. It's indicated by Orbit MFD as 'PeR' and this is an altitude above the planet center. From memory, IMFD Map Program also used this way of expressing altitude but then in meters above planet center. You can find the Venus mean radius in meters in the in-game info.

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 I didn't know actually, thanks a lot ! I've looked at the source code, but i'm quite a newbie in programming so I haven't find the values your mentionning, such as the timestamps... Where do I have to look actually ?
The data is not quite ready for grabbing. I am working at software at the moment which uses these values. That's how I knew about it. I'll think of a way to convert this data into ready-to-use data for Orbiter. It might take me a few days to come up with something. The question is, would it be helpful if we know the state vectors and accurate timestamps for every manouvre in the trajectory?

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 Finally, if i'm not mistaken, it does not give me any inclination right ? Or maybe i'm not looking at the right place.
Not sure about this. I think it's not needed.
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Old 11-20-2018, 12:36 PM   #19
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 TransX uses two-body solution in in calculations, so only a single, dominant body is considered, and different stages use the body appropriate for that stage.
I am aware of this behaviour actually, but does it mean that TransX Plan is not reliable or even doable because of its inacurracy ? I mean... to me the main objective is to be able to plan everything I can before take-off, and then proceed with that plan. Is it just fantasy haha ?

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Originally Posted by Tommy View Post
 Have the numbers for the swing-by written down and use IMFD's Delta-V program linked with IMFD's Map (in Plan mode) to make the MCC's.
You get the correct values from Trans-X, and use them in IMFD's Course program (use Off-axis transfer mode).
This part has lost me... I'm not able to find all these numbers in Tx. I might seem blind, but i'm just really confused.
If Tx gives me before the ejection burn an "Inc" value and a "Focus PeD", these numbers are no longer available after departure, since the displayed trajectory in Slinghot view isn't the planned one but the current one. Moreover, since I am not able to eject using IMFD Delta-v program in order to match perfectly both Inc. (which stands for Rinc and not EqI in IMFD right?), PeD, and Pe MJD between Tx plan and what IMFD'Map shows me, these values are changing in TransX during the trip (since the Pe MJD has changed too) ! So when I'm performing MCCs, i'm totally guessing the swing-by date and attitude I need to correct for.

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Originally Posted by Tommy View Post
 You will need at least one MCC, which can be made quite early, to correct the Distance and Inclination. This is easiest done as outlined above, with Delta-V, or it can be done using Target Offsetting in the Course Program.
For the first part, as I said above, once I ejected i cannot find out what the Distance and Inclination correct values are supposed to be since TransX displays the current trajectory, and not the planned one. Where can I find these values ?
Finally, I don't know in which thread i've read it, but can't we use the planet approach program in order to set up both PeD Pe MJD and Rinc ?

---------- Post added at 12:36 PM ---------- Previous post was at 12:30 PM ----------

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Originally Posted by Marijn View Post
 2.75 radii would mean 2.75 * Venus mean radius. It's indicated by Orbit MFD as 'PeR' and this is an altitude above the planet center. From memory, IMFD Map Program also used this way of expressing altitude but then in meters above planet center. You can find the Venus mean radius in meters in the in-game info.
Ok it's clear for me now, thanks !

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Originally Posted by Marijn View Post
 The data is not quite ready for grabbing. I am working at software at the moment which uses these values. That's how I knew about it. I'll think of a way to convert this data into ready-to-use data for Orbiter. It might take me a few days to come up with something. The question is, would it be helpful if we know the state vectors and accurate timestamps for every manouvre in the trajectory?
I don't know your program yet, but I can't wait meeting him :D As I said, it would be really cool if we could have an orbiter-friendly plan from trajbrowser, that you just have to follow, and with precise values you can refer to. Nasa's style is really tempting. Congrats for your work !

Last edited by potjoe; 11-20-2018 at 12:40 PM.
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Old 11-20-2018, 01:34 PM   #20
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 I don't know your program yet, but I can't wait meeting him :D As I said, it would be really cool if we could have an orbiter-friendly plan from trajbrowser, that you just have to follow, and with precise values you can refer to. Nasa's style is really tempting. Congrats for your work !
It will take some time before it's ready to use. I created it specificly for missions to asteroids so I need to fit planets in to make this of any use to you.

If you can't wait, you could try the following:

Lookup the source code of the Trajectory browser page of the link you posted above.

Your trajeory consist of 7 segments (legs), By chance of the ordering, these happen to be the last 7 values in each array. And we're only discussing the first leg to Venus. So the first value of these seven values are most interesting now:

You may recognize the first DV value, which is the 4.17 km/s ejection burn

Delta-V: 4172.99,0.045859,0,472.278,0.012143,0,2308.59

Timestamps are in JS2000 format: 684288000,684473098,702160280,702259200,702349431, 717357250,717465600
There's a recent post on this forum with the formula to convert them to MJD's.

In the same way, you could snatch the state vectors. They are in m/s. I think these are the most interesting:
VX: -1738.66
VY: -11821.3
VZ: -556.655

Perhaps this is the data which need to be entered into IMFD's Delta-Velocity program. Not sure if any conversion is needed. Can you check whether these values are of any practical use?

Other values in the source code need some post-processing apparently.
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Old 11-20-2018, 02:08 PM   #21
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 VX: -1738.66
VY: -11821.3
VZ: -556.655
Looking at it, I can already tell you it won't work : these state vectors seems to be relative to a sun-centered trajectory (they're all negative). However, you cannot use them to perform an ejection burn, because when you're ejecting, you're still under Earth's SOI, so to speak you're still referencing the Earth. This is why on IMFD you're setting your plan in the course Program, and then you have to use the Orbit eject program which "converts" your sun-centered velocities to earth-centered velocitites.

Is there a specific thread where you're following the development of your program ? I'd like to keep your work under an attentive eye
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Old 11-20-2018, 02:21 PM   #22
Marijn
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 Looking at it, I can already tell you it won't work : these state vectors seems to be relative to a sun-centered trajectory (they're all negative).
The data also includes a list of bodies which are orbited:
399,10,299,299,10,499,499

Earth is 399, sun is 10 etc.

So it seems the data is bound to a body being orbited.

The state vectors also inlude RX, RY and RZ. I don't know what they mean.

Would this change things?

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 Is there a specific thread where you're following the development of your program ? I'd like to keep your work under an attentive eye
Not yet, but I am getting close to a first version. It's a web-app, so I can send you a link to check it out.
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Old 11-20-2018, 04:51 PM   #23
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I've looked in Rx values, doesn't seem to help a lot here...

Sure I would be pleased to have have a look on your project
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Old 11-24-2018, 08:03 AM   #24
Tommy
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Originally Posted by potjoe View Post
 I am aware of this behaviour actually, but does it mean that TransX Plan is not reliable or even doable because of its inacurracy ? I mean... to me the main objective is to be able to plan everything I can before take-off, and then proceed with that plan. Is it just fantasy haha ?!
The TransX plan isn't perfect, but it's the best tool currently available for planning slings. The inaccuracies are small enough to be corrected with fairly small MCC's.

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Originally Posted by potjoe View Post
 
This part has lost me... I'm not able to find all these numbers in Tx. I might seem blind, but i'm just really confused.
If Tx gives me before the ejection burn an "Inc" value and a "Focus PeD", these numbers are no longer available after departure, since the displayed trajectory in Slinghot view isn't the planned one but the current one. Moreover, since I am not able to eject using IMFD Delta-v program in order to match perfectly both Inc. (which stands for Rinc and not EqI in IMFD right?), PeD, and Pe MJD between Tx plan and what IMFD'Map shows me, these values are changing in TransX during the trip (since the Pe MJD has changed too) ! So when I'm performing MCCs, i'm totally guessing the swing-by date and attitude I need to correct for. !
Very simple solution for this, involves a pencil and paper. As you plan the trip in TransX, write down the values. Use those values for the MCC's, ignoring what TransX is telling you after the ejection.

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Originally Posted by potjoe View Post
 
For the first part, as I said above, once I ejected i cannot find out what the Distance and Inclination correct values are supposed to be since TransX displays the current trajectory, and not the planned one. Where can I find these values ?
Finally, I don't know in which thread i've read it, but can't we use the planet approach program in order to set up both PeD Pe MJD and Rinc ?!
Planet Approch only works once you are very close to the planet's SOI, by which time the correction requires a lot of dV. Using Delta-V and Map you can fine tune the approach much farther out when it's more efficient.

Last edited by Tommy; 11-24-2018 at 08:06 AM.
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Old 01-14-2019, 12:21 PM   #25
Marijn
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 I've looked in Rx values, doesn't seem to help a lot here...

Sure I would be pleased to have have a look on your project
Hi Potjoe,
It took a little longer than anticipated, but I got a more or less working version I'd like you to have a look at. Do you have some spare time? It's working as intended in Google Chrome only at the moment.
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Old 01-14-2019, 12:56 PM   #26
potjoe
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Hi Marjin,

A bit busy at the moment, but PM me the link, I'll try to have a look when I have some time today and during following days.
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Old 01-15-2019, 06:15 PM   #27
Marijn
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 .. but PM me the link
Link and some explanation sent. Let me know what you think or run into.

---------- Post added at 07:31 PM ---------- Previous post was at 06:39 PM ----------

Oh. I forgot about a little change I made a long time ago affecting the total crew mass of a fully manned XR5. I am using XRSound and not UMMU which somehow results in a little different total crew mass.

I can't change this quickly now, but if you give crewmember Teal'c a mass of 54 instead of the default 104, the total crew mass should become 1224. Then all delta-v calculations on the screen should be confirmed by BurnTimeCalc upon scenario load.

---------- Post added 01-15-19 at 07:15 PM ---------- Previous post was 01-14-19 at 07:31 PM ----------

Hmm. I noticed we share the same user profile.. Will fix that when you are finished having a look..
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