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irnenginer

Joined: 29 Jan 2006
Posts: 64

 Posted: Sat Feb 25, 2006 5:41 am    Post subject: Putting values both for delV and gamma deem to confuse it. Try 0 for delv and -5.1 for gamma. The program should determine the minimum burn to provide that gamma value. It has worked for me consistantly. In fact the burn that is performed seems to put the CSM in the attitude for SM jet as part of the burn, with the nose down at an angle to the horizon. I run P37 at about 30min before the burn
Christophe

Joined: 09 Feb 2005
Posts: 280
Location: France

Posted: Sun Feb 26, 2006 8:28 am    Post subject:

 irnenginer wrote: Putting values both for delV and gamma deem to confuse it. Try 0 for delv and -5.1 for gamma. The program should determine the minimum burn to provide that gamma value. It has worked for me consistantly. In fact the burn that is performed seems to put the CSM in the attitude for SM jet as part of the burn, with the nose down at an angle to the horizon. I run P37 at about 30min before the burn

hi irnenginer!

I'm being studying both P37 and DAP procedures for reentry.

-VPRED: according to A15DELCO, I agree with you: 0 is the number you have to enter for max delta V (F 06 60) in order for the CMC to compute the min delta V for the burn. That save fuel. More details are explained in A15DELCO P37 assumption 2.

-Gamma value: It's the reentry angle at E/I (400kft). your value, -5.1° , seems to be very high for me as far as you enters from earth orbit.
From lunar entry nominal angle is 6.50°, it's very easy to confirm this value with any doc file, but for earth orbit entry, it's more difficult.
Looking at "Apollo by the numbers" pdf doc file, report entry flight path were:
-2.0720° for Apollo 7
-1.74) for Apollo 9.
I'll try with a mean value of -2.0° from earth orbit.

An other issue seems to be the TIG setting. As I understand you have to enter it at the beginning (F 06 33). I will try to use an orbiter MFD, may be IMFD with base approach program to compute a burn for entry targeting a specified landing site with appropriate value. This will give me a predicted efficient time for the maneuver I will further enter in P37 V06 N33 and see if this works.
The problem is that with the current beta modules I'm unable to use a saved scenario. Each time I try I experienced a "jammed CMC" that does not accept any entry. So I have to relaunch a new mission each time. Very boring...

Cheers...
Tschachim

Joined: 26 Nov 2004
Posts: 1272

Posted: Sun Feb 26, 2006 3:30 pm    Post subject:

 Christophe wrote: The problem is that with the current beta modules I'm unable to use a saved scenario. Each time I try I experienced a "jammed CMC" that does not accept any entry. So I have to relaunch a new mission each time. Very boring...

Sorry, then I'll make new beta modules ASAP, propably tomorrow. With the current CVS version saving/loading works fine for me, but movieman reported bugs like this, so we can check that then. By the way: Did you try to build the current CVS version with VS 2005 Express?

Cheers
Tschachim
Christophe

Joined: 09 Feb 2005
Posts: 280
Location: France

Posted: Sun Feb 26, 2006 3:47 pm    Post subject:

In fact I've managed to reuse some saved scenario by rewriting the environment setting: it's just because the quick save automatically reset the environment to project Apollo/sol instead of project Apollo/sol_VirtualAGC.
But that doesn't always fix the problem. Sometime the scenario works well and sometime not. I don't know exactly why
 Quote: By the way: Did you try to build the current CVS version with VS 2005 Express?

I 've send you a mail a few days ago with the last error and warning messages I have when I try to build. Did you get it?
It's better now cause I can build somme dll's but not the entire project.
And as you ever know "C++" means "Chinese ++" for me
Tschachim

Joined: 26 Nov 2004
Posts: 1272

Posted: Mon Feb 27, 2006 2:44 pm    Post subject:

 Christophe wrote: In fact I've managed to reuse some saved scenario by rewriting the environment setting: it's just because the quick save automatically reset the environment to project Apollo/sol instead of project Apollo/sol_VirtualAGC.

Thanks for pointing that out, there was a bug in the config file, it's fixed now.

 Quote: I 've send you a mail a few days ago with the last error and warning messages I have when I try to build. Did you get it?

Last mail I got was from Feb. 10, I did some changes and answered at Feb. 21, but my email account was broken at the weekend. Looks like dseagrav did also some changes because of more recent compilers, perhaps it's a good idea to update the sources, re-try and mail me again.

I have a horrible flu, I fear beta modules have to wait a little bit...

Cheers
Tschachim
movieman

Joined: 25 Nov 2004
Posts: 1018

 Posted: Mon Feb 27, 2006 2:59 pm    Post subject: I know we don't save absolutely all Virtual AGC state information in the scenario, but I believe we save as much as we should have to: it's possible there's something I've missed which doesn't work properly when it's zeroed on reloading the scenario. Working or not working seems pretty random for me.
Swatch

Joined: 15 Feb 2006
Posts: 262
Location: Cincinnati, Ohio

 Posted: Sat Mar 04, 2006 4:13 pm    Post subject: I meant to ask if the goal eventually was to combine Virtual Apollo with the rest of Project Apollo. (need this information for the Progress Thread) The alternative is to leave them as two seperate things that use two seperate scenarios. This seems quite inefficient however. Anyway, curiosity.
Christophe

Joined: 09 Feb 2005
Posts: 280
Location: France

dseagrav

Joined: 03 Dec 2005
Posts: 216

Swatch

Joined: 15 Feb 2006
Posts: 262
Location: Cincinnati, Ohio

 Posted: Mon Mar 06, 2006 10:53 pm    Post subject: To be honest....this sounds very interesting, but time consuming. Perhaps in the future this would be possible (like when we'll also be able to have multiple crew members in orbiter ). In the meantime, if someone were looking to impliment this...I'd say the best solution would be to write an MCC MFD (oh noes!) It's been mentioned spuradically throughout the forum, but not much has come of it. Ideally, someday, we'll be able to simulate MCC itself (imagine the panels involved there ), but I know somebody suggested having a MFD that "communicated" with you as an astronaut, similar to how CapCom did. Sounds reasonable and at the same time not extremely hard.
LazyD

Joined: 10 May 2005
Posts: 406

 Posted: Tue Mar 07, 2006 12:52 am    Post subject: Hi Christophe and dseagrav, I don't know much about the vAGC, but have been watching the advances you guys are making with interest. I have also been thinking about how to deal with simulating the role of MOCR, and several possibilities have been discussed. The simplest is to have an MFD that can do the orbital calculations and output delta V and burn times that could then be entered into the AGC. Most of these calculations are quite easy, the TLI and TEI are more complicated. I am already working on a general-purpose MFD that will calculate and perform these burns, or could output the numbers to be entered into the AGC. What I would rather do is write a standalone program that would compute trajectories outside of Orbiter, and could generate burn parameters that could be acted on by any autopilot MFD or the AGC. Since many of the calculations are iterative and time-consuming, it wouldn't compromise the simulation that way. And communication between such a tool and the AGC could be as simple as reading a file. The sticky part of this is trying to duplicate the ephemeris data inside Orbiter outside Orbiter. Anyway, my main interest is orbital mechanics and powered flight guidance, and I would enjoy working on this whatever form the tool takes. The number-crunching will be the same anyway, whether it's an MFD or a standalone program, and I'm glad to help with this. I'm not a very good coder, though, and I'm kinda lazy. I'm glad you brought this up, dseagrav, because I think it will be the next barrier we run into when the vAGC can do everything it really did. D.
irnenginer

Joined: 29 Jan 2006
Posts: 64

Christophe

Joined: 09 Feb 2005
Posts: 280
Location: France

Posted: Tue Mar 07, 2006 9:54 am    Post subject:

Hi !
Glad to see that irnenginer, dseagrav, Swatch, LazyD... all the big brains are in action
 dseagrav wrote: Guys, if you're reading this, I'm really, really, really, really, very eternally sorry I wasted your time and lied to you

If there is only one guy that doesn't waste our time (at least mine) it's you
In only a few days you wired a bunch of features we were wainting for so long: working RCS under DAP control, RHC, FDAI rate needles... the list is so long.
Never mind about AFPP, this is past. Just stay with us.
 Lazy D wrote: I am already working on a general-purpose MFD that will calculate and perform these burns, or could output the numbers to be entered into the AGC.

 irnenginer wrote: So what we need is a VRTCC. An orbital predictor that could take downlink data from the VAGC (which it can do). Compute burn data based of that point for the upcoming mission events (Like LOI and LEI) and uplink those back up to VAGC (which it also can) All we really need is something to spit out a state vector and time as the aim point that we can "uplink" to VAGC.

 dseagrav wrote: Mission Control is just another subsystem of the ship

That sounds like everybody is thinking roughly the same way:
A calculator that computes trajectories in the way irneginer pointed out and we can called virtual RTCC or virtual Mission Control and displays digits to be entered or uplinked into the AGC.
 irnenginer wrote: P31 was used far more then P30 for most burns, like TEI, LOI, and Midcourse

Sorry but I have some doubt about that... According to most of documentations, P30 was usually used for almost all burns, especially MCC's LOI and TEI. I don't say it's impossible to use P31 to do that, after all I never use it in such a purpose and it's worth the price to try, but I'm just saying that I never read things like that.
LazyD

Joined: 10 May 2005
Posts: 406

 Posted: Tue Mar 07, 2006 3:17 pm    Post subject: irnenginer, It would be equally easy to output a destination aim point and arrival time as a burn time and delta V vector - the two imply each other. In fact I am going to use Lambert steering for my MFD. My calculation code is easily portable, so we can do this in any form that works for the vAGC. I will need some help with uplink and downlink, and making sure our coordinate systems and units correspond, but I think I can handle the number crunching part. My TLI code isn't finished yet, but it's getting close. When the next version of Orbiter comes out, the internal ephemeris routines will be available and prediction accuracy will be improved, but it's not too bad the way it is. It starts in a parking orbit, calculates the length of time it will take for the target (moon) to intersect the parking orbit plane, then calculates a transfer trajectory that gets there at the same time. The nit-picky part is trying to into the proper moon orbit plane to pass over the landing site at landing time. D.
Christophe

Joined: 09 Feb 2005
Posts: 280
Location: France

Posted: Tue Mar 07, 2006 6:03 pm    Post subject:

 Quote: It starts in a parking orbit, calculates the length of time it will take for the target (moon) to intersect the parking orbit plane, then calculates a transfer trajectory that gets there at the same time. The nit-picky part is trying to into the proper moon orbit plane to pass over the landing site at landing time.

Are you sure this way of doing can match a real Apollo timeline?
Just a question.
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