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Project Apollo Beta 7.0 released!
http://nassp.sf.net/wiki/Installation
25068 Posts in 2094 Topics by 2266 Members
Latest Member: twa517
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1  Project Apollo - NASSP / Project Apollo - NASSP News & Discussion / Re: RIP Gene Cernan on: January 16, 2017, 05:19:33 PM
Only half of the moonwalkers are still with us.  At the rate we're (not) progressing, they'll all be gone by the time we put boots back on the Moon.  And while I'm sad at his loss and have sympathy for his family and friends, there's something else I'm feeling.

I'm angry.

We stopped going to the Moon because we "needed" the money for other things.  We had to fight a war in Southeast Asia: a war which we lost.  We needed a "war on poverty": a war which, after fighting it for 50 years, hasn't reduced the poverty rate.  But here was this amazing, incredible thing that we did, and did it successfully.  A thing which has provided spin-offs that we used every damn day of our lives.  That's what we chose to stop doing.

It's the fault of the American people, who were too short-sighted to see where this was going to lead.  It's the fault of Congress and every administration for not having the guts to say to the people-this is going to pay off far more than it's costing.

I really believe that when the history of this country is written in future centuries, stopping flights to the Moon and beyond are going to be seen as possibly the dumbest thing this country did.
2  Project Apollo - NASSP / Project Apollo - NASSP Development / Re: Kevin Bacon Challenge on: November 09, 2016, 05:57:06 AM
I like the idea of "challenges", but I'm not sure having them as an introduction would be the best course.

There's going to be a steep learning curve for someone not familiar with flying the CM, and a situation like that isn't something where you've got time to read the manual.  Continually killing them in the first five minutes could prove discouraging Very Happy
3  Meadville Space Center / Off Topic / Re: NASSP 'OOPS' collection on: September 14, 2016, 07:08:56 PM
For me, I found that I could only "hand dock" if I only did one thing at a time until I was facing the LM:  Get separation distance, stop. Turn CSM around, stop. Begin moving toward LM.  At that point, I could make small alignment adjustments while moving toward the LM and dock relatively easily, but if (for example) I tried to turn the CSM while it was still moving away from the stack, there was a lot of profanity involved  Wink
4  Project Apollo - NASSP / Project Apollo - NASSP News & Discussion / Re: Proper reentry procedure on: January 19, 2016, 06:07:06 PM

For example, if you're passing 4 on the scroll, but EMS reads 4100, you're undershooting by 100NM. If it reads 3900 you're undershooting by 100NM.

One of those (I'm guessing the one where the EMS says 3900) should mean you're overshooting by 100NMi.
5  Project Apollo - NASSP / Project Apollo - NASSP News & Discussion / Re: Apollo 8 VAGC on: October 22, 2014, 12:16:55 AM
Yes, OpenOffice is free.
6  Project Apollo - NASSP / Planning / Re: First Official Release on: July 20, 2014, 01:44:45 PM

Have you considered covering your entire kitchen and your daughter in plastic drop cloths?  ROTFL
7  Project Apollo - NASSP / Support & Bugs / Re: Earth Orbit Sep on: April 28, 2014, 05:45:26 PM
You actually answered your own question Thumbs Up  It's the three angles you get (roll, pitch, yaw) if you do a v16n20.

Those are the three angles for the CSM (and by extension, the SIVB) before you separate.  After separation, you want to rotate the CSM to the R22, P22, and Y22 angles that you've calculated--that way, you'll be in the proper orientation for docking.
8  Project Apollo - NASSP / Project Apollo - NASSP News & Discussion / NASA to release a bunch of code on: April 04, 2014, 02:09:36 AM
Not sure if this will help with NASSP development, but there might be some things that can untangle a few of the knots...

http://www.wired.com/2014/04/nasa-guidebook/
9  Project Apollo - NASSP / Project Apollo - NASSP News & Discussion / Re: Fuel cell reactant valves on: March 17, 2014, 03:46:08 PM
The breakers are on Panel 226.  Go right to Panel 5, and then down.
10  Project Apollo - NASSP / Support & Bugs / Re: is a joystick work for NASSP ? on: May 07, 2013, 02:11:31 AM

That's the same one I use
11  Project Apollo - NASSP / Support & Bugs / Re: RHC and THC confusion on: October 06, 2012, 11:33:23 AM
Hi folks,

No matter how I set things in the Project Apollo Configuration, Controls tab, I cannot get translation control. I'm stumped. I'm working through 'CSM Separation Prep' using Apollo 7 vAGC. I've attached my scenario file, could someone take a look and tell me what I'm doing wrong.

Thanks

I'm not sure what's going on, but I know that if you switch from "CMC" to "SCS", you do have translation control.  Just taking a quick look, it appears that everything is set correctly, but that might offer a clue to someone .

Scott
12  Project Apollo - NASSP / Project Apollo - NASSP Development / Re: A7 rendezvous P34 and P35 on: October 02, 2012, 09:43:06 PM
Quote
The spreadsheet calculates the DeltaV f and DeltaV i/o that result in the correct attitude for the burn, but the 7.6 fps is just too much.  After seeing how much it overshot, I figured that a 4.8 or 4.9 fps burn in the same attitude would give the separation needed (4.9 puts us a little too far away, 4.8 is a little too close), so I divided the values in the sheet by 1.55 (7.6/4.9) to get the values for the burn, but still have the correct attitude.
This smells like either the sheet or you missed one coordinate system transformation. You took the dV from the sheet, put them in IMFD and then you burned manually or with the CMC?

I put the data into IMFD, which was shared with PAMFD.  I then used the "P30" button on the MFD to transfer the data to the computer, verified that it was correct (by running P30 on the computer and looking at all the data), then did the burn using P41.

Quote
OK--now I understand what it's telling me.  So, the values in R2 and R3 should help cancel out any errors in Y and Z that have built up with the previous burns, correct?
Not quite. It's the burn vector transformed to the LOS attitude, i.e. when the CSM is pointing on the SIVB at TPI you would have to burn R1 with the X-thrusters, R2 with the Y-thrusters and R3 with the Z-thrusters.

And now I understand even better--thanks!

Scott
13  Project Apollo - NASSP / Project Apollo - NASSP Development / Re: A7 rendezvous P34 and P35 on: October 02, 2012, 02:00:52 AM
How did you do that? When I tried it, I didn't get the orbits the sheet suggested.

I didn't either, but I wasn't aiming so much for the suggested orbit as to put the CSM in the correct position relative to the SIVB, and other than the phasing Delta V, using the suggested Delta V's puts me in the correct position relative to the SIVB after the CDH burn.  The orbital elements of the CSM and SIVB match up pretty well (within 1 degree for LPe, AgP, TrL and MnL.  Inc and LAN are spot on, and eccentricity is .0001 off).  And the TPI TIG predicted by P34 was within one minute of the time from the sheet.

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1. As I recall, the phasing burn from the S-IVB is actually supposed to be 2.5 fps, unless the new procedures suggest otherwise...

A 2.5 fps burn works to give you the separation if it's a pure retrograde maneuver, but the A7 phasing burn was done, according to the press kit, with a 72 degree pitch down attitude.  The spreadsheet calculates the DeltaV f and DeltaV i/o that result in the correct attitude for the burn, but the 7.6 fps is just too much.  After seeing how much it overshot, I figured that a 4.8 or 4.9 fps burn in the same attitude would give the separation needed (4.9 puts us a little too far away, 4.8 is a little too close), so I divided the values in the sheet by 1.55 (7.6/4.9) to get the values for the burn, but still have the correct attitude.

Quote
Our initial orbit (i.e. the orbit the Saturn IB puts us in) is different from the real AP7 orbit. This is caused by our 'simplified LVDC' (I hope this will get better once we have the LVDC++ running). Thus, it is possible that we won't get the exact dV-figures MSFN had planned. As long as we achieve the original orbit data and distances between both vehicles, everything's okay.

That's kind of my thinking as well--if we're ending up in the right position at the right time, then it's probably OK.

Quote
"at one point I get a V06N59..."  This is the dV in LOS coordinates, i.e. it is assumed that the CSM is pointing at the SIVB during the burn. A normal burn would have been done with the CSM aligned with the +x axis along the burn vector and using only forward translational thrust. This meant of course, that the CSM had to get from the tracking attitude to the burn attitude, stabilise, burn, get back to the tracking attitude, stabilise...very time consuming. Keeping the CSM at the tracking attitude saved time; the only price paid was that the astronaut had to use all thrusters to null the dV.

OK--now I understand what it's telling me.  So, the values in R2 and R3 should help cancel out any errors in Y and Z that have built up with the previous burns, correct?

Quote
"Also, if you don't have the state vector for the SIVB loaded in the "other vessel" address when you run P34, it will throw a 1301 error, which makes sense..."Of course it does. The CMC isn't the wizard of oz. It needs to know where it is and where it has to go to calculate the rendezvous.

Yeah, I just thought I'd point it out to anybody who missed a step and didn't know why that got that error (not that I ever did anything like that  Rolling Eyes)

Quote
"Can we just use a fresh state vector for the SIVB and call it good?..."When I remember right, MSFN provided a SIVB SV to start with shortly after NCC2. After that, P20 was used and marks were taken on the SIVB. VHF ranging wasn't used on AP7 - the SIVB had no equipment for that. Tracking the SIVB with P20 is possible in orbiter, I've tried that.

Well, if the ranging wasn't used, I'll stop trying it  ROTFL  And I'll back up and see if I can get the SIVB in the optics.

thanks for clearing up a bunch of stuff for me.
Scott
14  Project Apollo - NASSP / Project Apollo - NASSP Development / A7 rendezvous P34 and P35 on: October 01, 2012, 02:44:29 AM
After having real life get in the way, I'm finally getting back into using Orbiter, and am working on the rendezvous with the SIVB in Apollo 7.

I've been using Christophe's excellent RDV spreadsheet for the phasing, insertion and CDH burns, and have gotten pretty good results, with one tiny tweak.  Using the nominal 7.6 fps phasing burn puts us too far ahead of the SIVB at the time of the insertion burn.  This isn't a fault in the spreadsheet.  Using 4.8 or 4.9 fps gets the separation within 5 or 6 km of the "by the book" figures, and the subsequent insertion burn keeps the same "offset", so I think we're OK there.

My question has to do with the subsequent TPI, TPM, and TPF.  Using P34 gives me a good time for TPI (within 1 min of what RDV predicted), but while running through P34, at one point I get a V06N59, with the registers giving velocity for LOS 1, LOS 2, and LOS 3.  LOS 1 is the velocity to be gained at TPI, but I'm at a loss to figure out what points LOS 2 and LOS 3 are (the burns are very small; -1.0 fps for LOS 2, and +1.0 fps at LOS 3).  What I don't know is when those burns are.

Also, if you don't have the state vector for the SIVB loaded in the "other vessel" address when you run P34, it will throw a 1301 error, which makes sense--without position info on the SIVB, the angles become undefined.

Finally, in both P34 and P35, it mentions that you can pause at any flashing display and take optics marks (to refine the trajectory), or allow VHF ranging marks to accumulate.  Since the SIVB doesn't become visible until you're something like 20 km away, you can't take optics marks, and AFAIK, VHF ranging hasn't been implemented, so that doesn't work.  Can we just use a fresh state vector for the SIVB and call it good?

thanks,
Scott
15  Meadville Space Center / Off Topic / Re: Neil Armstrong passed away... on: August 25, 2012, 10:08:23 PM
I once heard an interesting way of looking at the magnitude of what A11 accomplished: "Neil Armstrong is possibly the only person born in the 20th century who will be widely remembered in the 30th".

Scott
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