IMFD some questions about IMFD

[bande]

hi there, I've some questions about some IMFD's features...
after managing an Earth-Moon transfer, time for an interplanetary trip! I read the IMFD full manual and began to setup the mission: an XR2 landed at Wideawake, UCGO Arrow waiting in orbit. launch, docking, crew transferred in the mothership, and ready for a trip to Mars!

I use IMFD 5.5 (think it's the latest version), planned a two-plane target intercept course on the left MFD, then performed the escape burn using "orbit eject" program on the right MFD (shared).
the scenario started with the Arrow in an eclipticorbit, so a plane change wasn't required. but what if I would had to, for example to perform an off-plane intercept?
so, after escaping Earth, waited to approach the node for the mid-course correction. I thought it could be made by pressing AutoBurn on the course display, but at ANY distance from the node, the autopilot rotates the ship and displays "burning (main)", but actually main engins weren't running!
so I missed the intercept and condemned the whole crew to certain death. I can't sleep well anymore at night.

 

[Bonanza123d]

You didn't condem the whole crew. If you know how to fix the situation, you can. What I do is simply use the Align Plain MFD and do it like you would do one for the ISS > Mir, but on a larger scale. It is that simple.

 

[Izack]

For an out-of-plane intercept, "Off-plane" will generally get you where you're going, but it may not be the most efficient route. Source or Target plane modes followed by a plane-change in the midcourse correction (there are more qualified people to tell you about this :s) could be very much more efficient, but it's dependent entirely on the situation.

As to your crew... if you still have the scenario, you can hack backwards in time with the scenario editor and try the burn again.

No idea why the engines weren't running. :shrug:

 

[bande]

maybe I didn't explain well what I meant: the point is how to perform a plane change in according to the course program data.
with a source/target/two plane intercept, obviously the plane is the ecliptic, with an alignment burn later, while an off-plane intercept a plane change is required before eject.
I just don't know how to do that

 

[Izack]

In an off-plane intercept, the plane change is performed during the eject burn. IMFD handles it automatically.

 

[bande]

really? so all I have to do is to set the eject course up and perform a later correction for an accurate orbit insert using "base approach"?
very nice I'll give a try immediately!

 

[Izack]

really? so all I have to do is to set the eject course up and perform a later correction for an accurate orbit insert using "base approach"?
very nice I'll give a try immediately!

Yes - given a good launch window and enough delta-v. But it is not always the most efficient way.

 

[bande]

I tried, and I made it!! it took a 303 days trip, but my XR2 finally undocked the Arrow in martian orbit

 

[orbekler]

Usually - but not always - the best way to save fuel is a Source-plane (or Two-plane) course, but it requires a second burn, you need to select Plc, press + and then AB again, after ejection. If all is ok you should see again a countdown for the Plc. You could even turn offsetting on and change LPC, so if you're far enough from Earth/Soi for Plc you'll save a fair amount of fuel, but with this latter method you have to take care not crossing the atmosphere or the surface during ejection (hehe - you'll have to get a ton of Valium to sleep). Of course the Off-plane is simpler, at a cost of (much) more fuel expense.
If you're already almost aligned, you could use Source-plane and perform a Base Approach correction, about at half way, so you could neglet Plc.

 

[bande]

select Plc, press + and then AB again, after ejection.

finally, that's what I was looking for. tomorrow I'll have a try, then focus on atmospheric reentry... anyway, this trip cost too much fuel; it took about 20% of Arrow's main fuel to reach a martian stable orbit, I might had saved a little more fuel if I hadn't performed multiple correction burns when too far from the planet. :thumbup:

 

[Izack]

finally, that's what I was looking for.

Argh, I thought's that was the part you already knew. Sorry about that! :facepalm:

 

[orbekler]

Don't worry too much about saving fuel, just enjoy the trip!
BTW: with IMFD usually you need just 1 or 2 corrections (I mostly use Base Approach), and to be sure a third just before reaching target periapsis (but if you did it right the previous manouvres, it will take just a bit of RCS).
Have a look to this, maybe you'll find useful:
[ame="http://vimeo.com/19699319"]UCGO Arrow Freighter + XR-2 - IMFD: Earth to Mars on Vimeo[/ame]
[ame="http://vimeo.com/19964095"]Orbiter - XR-2 Mars landing, undocking from UCGO A.F. on Vimeo[/ame]

 

[bande]

I'll take a look, I guess the first video is the one posted on FOI... but the second one focused on reentry will be very useful

@Izack: don't worry about that, you gave helpful hints as well :thumbup: