Earth to Venus IMFD

[Lupin_Yonder]

Hi there, first post for me
Been using obiter for a while though I’m no master, I used to use transx but I found that took ages to plot a course and all the manual burns were a pain so I’ve switched to IMFD 5.1

Currently I'm using the WO2001 mod and attempting the earth to Venus flight.

Starting from station 4 my inc for Venus is all wrong but aligning takes up a lot of fuel, is it possible to use IMFD to do an ejection burn from my current inc ?

Secondly when I attempt to set the orbit eject real-time parameter to off axis, it switches back to real-time. I do not understand this variable or why it switches.

 

[Urwumpe]

Yes, you can use it directly. I would make sure you select Earth as source when calculating the off-plane transfer.

 

[Lupin_Yonder]

I have been, i should also mention that i have been using tangential transfer for my course

 

[Urwumpe]

I have been, i should also mention that i have been using tangential transfer for my course

tangential transfer can't be off-plane, if I remember correctly.

 

[Lupin_Yonder]

Ah, thanx i will give it a try with the target intercept course program instead. The problem is that there are a tonne of options and veriables in that i cant find a FAQ or tutorial for :-(

P.S. When i do target intercept i still cant set the Realtime to Off plane and the ejection burn even when in realtime keeps stopping very early

 

[tblaxland]

P.S. When i do target intercept i still cant set the Realtime to Off plane and the ejection burn even when in realtime keeps stopping very early

In your Target Intercept program, are you using Earth as the source, as Urwumpe suggested? If so, are you using the Orbit Eject program to get your ship on this trajectory?

Some background: The Target Intercept program can calculate the path from Earth to Venus, but not your ship to Venus. This is because both Earth and Venus are orbiting the Sun, whereas your ship is orbiting Earth, and the Target Intercept program can only calculate the transfer for objects that are orbiting the same body. So what you do is calculate an interplanetary trajectory from Earth to Venus in the Target Intercept program, then use the Orbit Eject program to eject from Earth orbit onto that interplanetary trajectory. IIRC, in the Orbit Eject program defaults to "Higher Orbit", you will need change that to "Course".

EDIT: The Earth to Mars tutorial on jarmonik's website could be of some value to you.

 

[jedidia]

EDIT: The Earth to Mars tutorial on jarmonik's website could be of some value to you.

Note, though, that it is written for an older version of IMFD, and the changes where not too few. For example the surface mode of the Orbit-Eject programm changed so severly that I didn't notice that t actually was the surface mode... I tried a launch with the data of the default mode, and it worked without a problem, so I figured it was replaced. Can cause some confusion if you don't know it, however...

Also, the data-share mode has chaged, while in the tutorial it is written you only have to push the PG-button in the Main Menu of both MFDs, you now have to push it and assign the ID of the other MFD, and you ONLY have to do it in the MFD that is supposed to SEND data.

I think these where the major differences I encountered using that tutorial.

 

[tblaxland]

Thanks for the corrections.

 

[Lupin_Yonder]

Lupin_Yonder;15733]Thanx guys, will have a look at the 4.2 tutorial and check out earth 2 mars again, see if they clear anything up. I'm using 5.1 but i hear 4.2 got some useful bits of info..

Well i had a read and TBH i'm none the wiser so i've jotted down what i'm doing in sequence and where im having trouble.

So im attempting to luanch from station IV and Aquarius 1 to Venus

Start IMFD in L and R MDF's
R set to share IMFD ID 0
R set to Map
Ref=Sun
Tgt=Venus

L set to Target Intercept
Ref=Sun
Source=Earth
Target=Venus
Two plane ( for lowest Ov )
Realtime option grayed out, cant change to off axis
Change TIn to lower Ov

L set to Orbit Eject
Set to course
Ref=Earth
Should mention at this point that EIn is 18.9 Deg
Attempt to change realtime to Off axis but it resets to realtime
Auto burn often stops short of finishing burn

P.S. Thanks again for your help guys, once a crack this, the systems my cold dark oyster

 

[jedidia]

You don't need the Map for Orbit eject. better to have one MFD in target intercept mode and the other in Orbit eject mode slaved to it. The map only really starts to make sense when you leave the SOI of your starting planet...

Auto burn often stops short of finishing burn

Yeah, it is not as precise as I often wish, but it really is precise enough. If you're not satisfied with the burn, just burn a bit longer manually without changing your attitude, there you go.

On the other hand, burning too precise in the beinning stages doesn't make that much sense. You'll need to correct anyways, and the closer you get the mor precise it gets. (It's strange though that IMFD only seems capable to burn at full thrust...)

 

[Lupin_Yonder]

Thanx for the input but when i say short, i mean it just stops and i haven't got orbit eject speed. It stops WAY short

What im wondering about most is the realtime variable, i've read that it should be off axis for a course that starts in a different plane than the target, and i cant set either the target intercept or the orbit eject to it

 

[jedidia]

oh... strange, I never encountered that problem...

as for the realtime variable, I don't really know what it does either...

 

[Lupin_Yonder]

One other thing that bothers me is that all the guides i have read for IMDF assume that your taking off from the surface to the correct orbital inc for the target, now i thought IMFD could do off plane transfers but i cant find a guide that talks me through it.

I really want to go through the missions in 2001 mods, i can do most other parts of the missions but IMFD is really starting to frustrate me, it seems odd that there is not a clear guide for it, mind you lots of things in orbiter tend to assume that you have an indepth knowlage of orbital mechanics and an intuative skill with the MFD's. I dont want to go back to transx, it takes ages to use

 

[Urwumpe]

Orbiter is about orbital mechanics. Some basic knowledge should be useful.

For IMFD, it would be enough knowing the various maneuvers you can do... IMFD does the calculations quite well, once you can tell it what you want.

 

[Lupin_Yonder]

Yea, i may have come accross a bit pissed off in that last post, srry but as i said its frustrating.. I have read a fair amount of documents for orbiter and its taught me a huge ammount. I just simply don't know the processes to program what i want into IMFD, am i alone in this?

 

[streb2001]

I just simply don't know the processes to program what i want into IMFD, am i alone in this?

No.

 

[Urwumpe]

lets start simple. Do you know what Source (src) means in IMFD?

 

[Lupin_Yonder]

yup, its the starting ( source ) point for target intercept program and should be set to earth

 

[Urwumpe]

No, it is the navigation source. Depending on what you want to do and where you are, you have to select for example yourself as source.

 

[Lupin_Yonder]

thats kinda what i meant, but either way, using the target intercept you set earth as the source, if you look further up in this topic you can see step by step what i did, maybe you can see where im screwing up