|
Author
|
Topic: Timing of Aurora 7 (MA-7) retrofire burn
|
Colin Anderton
Member Posts: 173
From: Great Britain
Registered: Jan 2005
|
posted 05-19-2020 10:06 AM
   
To accompany my Mercury, Gemini and Apollo audiotapes, I’m currently working on videos showing the mission elapsed time throughout the flights, and of course that requires getting the tapes running at precisely the correct speed.I noticed while working on the Mercury-Atlas 7 flight that the Hawaii CapCom sent Scott Carpenter a time hack at 4 hours, 29 minutes and 30 seconds that was in fact three seconds late. With several things occupying Carpenter's attention at that point, could this ground station error have possibly contributed to the late firing of the retro-rockets? Al Shepard at the Cape did then send a correct retro sequence check at 4 hours, 32 minutes and 39 seconds. Is it possible Carpenter had reset his clock to the incorrect Hawaii call, and then left his clock set at the incorrect time, thereby innocently firing the retros three seconds later than planned? |
Headshot
Member Posts: 915
From: Vancouver, WA, USA
Registered: Feb 2012
|
posted 05-19-2020 10:43 AM
How did Carpenter acknowledge Shepard's new time hack? Did he respond that he received it; or that he received it and had implemented it? |
ejectr
Member Posts: 1765
From: Killingly, CT
Registered: Mar 2002
|
posted 05-19-2020 12:03 PM
I see more than a 3 second difference in those two figures... |
Colin Anderton
Member Posts: 173
From: Great Britain
Registered: Jan 2005
|
posted 05-19-2020 12:04 PM
The two time hacks were given at different times. It's just that the first call was three seconds off; the second was accurate. quote:
Originally posted by Headshot:
How did Carpenter acknowledge Shepard's new time hack?
I'll get back to you on that tomorrow. Thanks for the reply. |
moorouge
Member Posts: 2466
From: U.K.
Registered: Jul 2009
|
posted 05-19-2020 04:00 PM
quote:
Originally posted by Colin Anderton:
...could this ground station error have possibly contributed to the late firing of the retro-rockets?
This extract of from a piece I wrote on the flight of Aurora 7 might help - The countdown given by Shepard reached zero. Nothing happened. At this point everyone was expecting the automatic sequencer to fire the three retro-rockets. Carpenter hit the manual override button. And again – nothing happened. There was a two second delay before the rockets actually fired producing in the cabin a puff of acrid smoke probably caused by a short circuit in the firing mechanism. This delay contributed some 15 to 20 miles to the overshoot on landing. When the rockets fired in their ripple pattern they did not produce the kick that Carpenter was expecting. This loss of the expected thrust added another 60 miles. The remaining 170 or so miles came as a result of a misalignment during retrofire. Not in the vital pitch angle but in yaw. When the rockets fired the capsule was slanted about 25 degrees off to the right. As retrofire progressed Carpenter gradually brought this back to zero, but because the rockets did not fire in an absolutely straight line down the flight path they lost effectiveness. All three elements added up to 250 miles over the expected landing point. |
Colin Anderton
Member Posts: 173
From: Great Britain
Registered: Jan 2005
|
posted 05-20-2020 02:45 AM
Thanks for clearing that up. I guess that settles it. |
Colin Anderton
Member Posts: 173
From: Great Britain
Registered: Jan 2005
|
posted 05-20-2020 03:04 PM
quote:
Originally posted by Headshot:
How did Carpenter acknowledge Shepard's new time hack?
Actually, he didn't acknowledge the first incorrect call, and just responded with a "Roger" to Shepard's countdown to retro sequence.But, as above, it seems this was irrelevant to the off-target landing anyway. |
advertisement