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Author Topic: sps burn issue  (Read 6461 times)
Mike Skanz
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« on: April 29, 2013, 07:58:50 PM »

ok, like a newbie, my spacecraft is pointing his nose face to the earth for my third sps burn, so i know its supose to be more in a prograde position but i dont know what im doing wrong (follow all the a7 sps burn chklist and have a p52 option 1 of five ball and have a burn of about 30,9ft/sec) i already read a post about a similar problem but i dont seem to find a solution to my prob...(maybe cause im french and i cant follow the discussion very well so.... a little help would be very apreciate. thank you
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eddievhfan1984
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« Reply #1 on: April 29, 2013, 11:59:02 PM »

What orbital change is supposed to occur with SPS burn 3?
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Mike Skanz
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« Reply #2 on: April 30, 2013, 07:37:31 AM »

it's suppose to raise my apogee at an altitude of about 295,7km
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eddievhfan1984
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« Reply #3 on: April 30, 2013, 04:13:55 PM »

Did you also SV update for the burn?
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Mike Skanz
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« Reply #4 on: April 30, 2013, 04:38:28 PM »

yep, SV are done... and when P40 is doing the burn, the sps gimble indicator are all the way down and the spacecraft are tumbling end over end
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Mike Skanz
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« Reply #5 on: April 30, 2013, 04:43:19 PM »

i will try to attach a scenario when i will be at home

http://www.ibiblio.org/mscorbit/mscforum/index.php?topic=2256.0

this guyz seem to have the same issue as me but i cant find a way to resolve my problem as i already said
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eddievhfan1984
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« Reply #6 on: April 30, 2013, 05:43:25 PM »

Were the gimbals centered before the burn started?
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Mike Skanz
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« Reply #7 on: April 30, 2013, 06:10:53 PM »

yes they are centered

here a scenario at around TIG -10:00 (on the DET)

* (Current state) 0001.scn (111.77 KB - downloaded 131 times.)
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rcflyinghokie
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« Reply #8 on: April 30, 2013, 11:59:27 PM »

How are you getting your Delta V values for this burn.  Also, your ORDEAL is still driving one of your 8 balls, might want to turn that off to avoid confusion for now....
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meik84
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« Reply #9 on: May 01, 2013, 12:21:09 AM »

Sorry, but I can't confirm your problems. The only thing you missed was a SV update. Do it before you run P30 (or run P30 again, after you zapped in the update) and voila -you burn will be perfectly prograde. I also can't confirm your problems with the gimbals; the TVC DAP shouldn't touch them anway, the burn is too short.
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Mike Skanz
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« Reply #10 on: May 01, 2013, 12:25:22 PM »

How are you getting your Delta V values for this burn.

I get my DV values by doing this (according to the Apollo 7 Flightplan vAGC.xls):

MFD1   Open Interplanetary MFD            
   Click "MNU"            
   Click "MOD" (Configuration)            
   Click "NXT" until "LambertAP Mode" is selected            
   Click "+" to select "Apollo P30"            
   Click "MNU"            
   Click the "Course" button            
   Click "NXT" until "Delta Velocity" is selected            
   Click "SET"            
   Click the "+" or "-" buttons until the GET displays the time of the burn in the table below. Use "ADJ" to adjust the increments as necessary            
   Click "NXT" and use the "+" or "-" buttons to adjust the "dVf" and "dVi" to the base velocities in the table below to start with            
   Adjust "dVf" and "dVi" until the ApA and PeA relate closely to the base ApA/PeA in the km column below            

MFD2   Open Project Apollo MFD         
   Click the "IMFD" button         
   Click "REQ" to request burn velocities from MFD1 in ft/sec         
   Click "BCK"         
   Click "TELE"         
   Click "P30"         
2   UPTLM/CM - ACCEPT (UP)         
MFD2   Click "P30"   burn data will uplink, wait for UPTLM light to extinguish      
2   UPTLM/CM - BLOCK (DOWN)         
DSKY   V37E 30E         
   Line 1: 00xxx   GET of burn in hours      
   Line 2: 000xx   GET of burn in minutes      
   Line 3: 0xx.xx   GET of burn in .01 seconds      
   Verify the GET of the burn is sufficient with what is displayed in IMFD         
   PRO         
   Line 1: xxxx.x   dV x in 0.1 ft/sec      
   Line 2: xxxx.x   dV y in 0.1 ft/sec      
   Line 3: xxxx.x   dV z in 0.1 ft/sec      
MFD2            
                 PRO                    COMP ACTY will light for a moment      
   Line 1: 0xxx.x   predicted ApA after burn in nm      
   Line 2: 0xxx.x   predicted PeA after burn in nm      
   Line 3: xxxx.x   total dV in 0.1 ft/sec      
         
1   EMS FUNC - dV SET/VHF RNG (TURN)         
   dV EMS SET - INCR or DECR         
   Increase until "dV RANGE" indicator displays the dV displayed in Line 3 of the DSKY         
   EMS FUNC - dV (TURN)         

« Last Edit: May 01, 2013, 12:27:33 PM by Mike Skanz » Logged
Mike Skanz
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« Reply #11 on: May 03, 2013, 06:26:23 PM »

well, i do a SV before redoing P30 but she is not prograde anymore when doing P40   Bangs Head 2
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eddievhfan1984
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« Reply #12 on: May 03, 2013, 10:45:31 PM »

Do you manually input the burn variables into P30, or do you use the MFD to upload the burn variables?
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Mike Skanz
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« Reply #13 on: May 06, 2013, 05:06:27 PM »

i think i know what i do wrong : when i was proceed to the Braking Phase Maneuver i was approching at 100m/sec at a distance of around 15k meters and i was not able to brake at time to avoid colision. to not miss the rendez vous, i copied the state vector from the S-IVB (this is probably here i fucked up for my later 3rd SPS burn (so i will try to redo it from the rendezvous to see if im right)
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eddievhfan1984
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« Reply #14 on: May 06, 2013, 07:02:25 PM »

You didn't use the TPF program to control braking? And I believe the forum code of conduct requests no cursing. Tongue Just thought you should know.
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