Space Shuttle Ultra - quick question re: MFDs

[jungzimm]

Ah, that sounds like what I'm looking for. Thanks very much. I'll check it out.

John

 

[bujin]

Just out of interest, what units are used? I gather the shuttle uses FPS, but Orbiter is metric.

 

[DaveS]

Just out of interest, what units are used? I gather the shuttle uses FPS, but Orbiter is metric.

SSU uses the imperial system.

 

[tblaxland]

jungzimm: What you need to tell the GPCs is your desired burn time in Mission Elapsed Time(MET) which is the format of ddd:hh:mm:ss, the desired delta V is feet per second(fps) in all three axes(X, Y and Z) where X is forward/backward, Y is left/right and Z is up/down.

The reference frame is +XVV, -ZLV with right-hand coordinates? You could get figures from the IMFD Delta-V program.

 

[jungzimm]

Thanks everyone. I used the equation mfd to get the DV and converted it from mps to feet per second to put into the MM202 of the CRT MFD. I put the whole thing into the Y axis (item 19) if I remember right. I did a rough calculation on the burn time from the info in the Allign planes mfd and enterred a TIG in items 11,12,and 13 of the CFT mfd. Loaded, manuvered and waited it worked. Got the planes alligned down to within 0.13 degrees. Used the sync mfd and set up prograde burns and eventually got close enough to maneuver and dock using docking mfd. I did have to cheat and add some more RCS fuel a couple of times due to my sloppy docking and maneurvering skills but I finally got there and docked. Next time I'll have to try it without having to stop at the gas station. The equation mfd would have been way over my head without the example they included on how to set up an allignment from their tutorials. If I knew more orbital mechanics and what all the variables stand for, it looks like an incredibly useful tool. I haven't used IMFD 5 and and still trying to figure out how to set it up to get the DV in LVLH feet per second but it looks like it would be quicker than equationMFD once I get learn how.

Resting now for a while and enjoying some of the great space food at the ISS.

John

 

[jungzimm]

SSU setting up plane allignment.

OK, I'm back with a process that I'd like comments on from anyone familiar with IMFD. I've launched and arrived in orbit with a needed plane change of 1.4 degrees obtained from the align planes mfd. I open IMFD 5.1 and go to the map program where I set up the ISS as target. I then note it is showing a Plc dv of 193 m/s and a time to node of 1750 sec. I then open the Delta V program in the Course Program list, set the target for ISS, and set up the TEJ with 1750, zero the Dvf (which defaults to 10 for some reason) plug the 193 into the Dvp and set the program for local vertical. I go to the burn screen and get a time till burn value and also a length of burn value.

Now I go back to OPS 202 in the CRT mfd. There I enter -5.7 and 5.7 in the trim items for left and right. I add the time till burn from the IMFD to the present MET and set that up in items 10,11,12,13. I then convert the 193 m/s to feet/second and enter 625 into the Dvy item 20. Hit load (item 22) hit maneuver (item27) and then item 23 to display the countdown timer. I arm the obs, sit back and wait for it all to go down. Results aren't perfect but they're close. Gets the Rinc down to about 0.13 degrees as displayed in the change planes MFD.

If I'm messing up somewhere please let me know.

Thanks,

John

 

[Donamy]

You should do a detailed tutorial for the SSU.

 

[C3PO]

Iv'e been tinkering with a spread sheet for calculating fps inputs.

It kinda grew past it's scope.

You can point your craft with TransX or RendezvousMFD, read the direction from Orbital HUD, and enter the direction.

Enter the DV, DT and current MET, and you should have the correct numbers to enter into CRT MFD.

Don't worry about the sma, ecc and PeT. They are only for the Apd/PeD/Circ calculations.

I run it on a laptop to avoid task switching.
View attachment SSUltraCalc.zip

 

[tblaxland]

Gets the Rinc down to about 0.13 degrees as displayed in the change planes MFD.

You could probably get your 0.13 degrees even lower if you started your burn a little bit earlier.

Your procedure starts the burn at the node crossing time which means you have already missed the node by the time your burn is half over. Put your DV into BurnTimeCalcMFD and it will tell you the "half Delta-V" time. Subtract this from your IMFD "time to node" to get your "time to burn".

Here is a picture from [ame="http://www.orbithangar.com/searchid.php?ID=3074"]another tutorial[/ame] to help to illustrate the need to burn before reaching the node:

 

[jungzimm]

Donamy--Hope to do a tuturial once I get my results to be a bit more consistent.

C3PO--Thanks for the SSUltraCalc. Still trying to find time to try it. Life keeps getting in the way.

TBLAXLAND--I think IMFD compensates for the burn at node by giving a "time to Burn" that is adhead of the node intercept. That's why I plugged the "time to node" into IMFD's "time to eject" and then used the "time to burn" from the BurnValue Page to enter into the CRTmfd. I will check this out the next time I fly." I had never seen the tutorial you referenced and really learned a lot about the behavior of different velocity vectors when two vessels are in orbit in close proximity.

Thanks to all.