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  Saturn V S-IC engine start sequence

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Author Topic:   Saturn V S-IC engine start sequence
LM-12
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Posts: 2458
From: Ontario, Canada
Registered: Oct 2010

posted 01-17-2018 04:56 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
It is interesting to note that during launch of the Saturn V, the startup sequence for the five F-1 engines of the S-IC first stage was not the same for each flight.

From the AS-512 (Apollo 17) launch vehicle flight evaluation report:

Structurally, a 1-2-2 start is desired for minimizing the start and liftoff dynamics caused by thrust buildup of the engines ...

The planned 1-2-2 F-1 engine start sequence ( engines 5, 3-1, 4-2 ) was not achieved. Two engines are considered to start together if both thrust chamber pressures reach 100 psig within 100 milliseconds. By this definition, the starting order was 2-1-1-1 ( engines 5-3, 1, 4, 2 ) ...

The desired 1-2-2 start sequence was also not achieved on flights AS-507, AS-508 and AS-510.

Here is a list of the sequences based on information in the flight evaluation reports:

flightengine start
sequence
engine position
starting order
AS-5011-2-25, 3-1, 4-2
AS-5021-2-25, 1-3, 2-4
AS-5031-2-25, 3-1, 2-4
AS-5041-2-25, 3-1, 2-4
AS-5051-2-25, 3-1, 2-4
AS-5061-2-25, 1-3, 4-2
AS-5071-2-1-15, 1-3, 2, 4
AS-5081-2-1-15, 1-3, 2, 4
AS-5091-2-25, 1-3, 2-4
AS-5101-1-2-15, 3, 2-4, 1
AS-5111-2-25, 3-1, 4-2
AS-5122-1-1-15-3, 1, 4, 2
AS-5131-1-1-1-15, 3, 1, 2, 4

LM-12
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Posts: 2458
From: Ontario, Canada
Registered: Oct 2010

posted 01-18-2018 08:11 AM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
The command module main display console has five F-1 engine indicator lights on Panel 1. From the CSM Displays & Controls document:
LV RATE light glows red if launch vehicle angular rates are excessive, which can automatically initiate abort; LV GUID light glows red to indicate failure in launch vehicle guidance system, which can result in abort; SII SEP light glows white when staging is initiated and goes out when interstage skirt drops away from S-II after ignition; LV
ENGINES lights (arranged in same pattern as on vehicle - 1, 2, 3, and 4 are outboard and 5 is inboard) glow yellow before ignition
and go out when an engine reaches 90 percent of thrust; No. 1 light also operated for third-stage engine; two lights glowing (two engines below 90 percent thrust) can initiate automatic abort during first-stage burning.

LM-12
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From: Ontario, Canada
Registered: Oct 2010

posted 01-21-2018 12:43 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
In this view of SA-500F at Pad 39A, the engine 1 position is at Fin A, the engine 2 position is at Fin B, the engine 3 position is at Fin C, and the engine 4 position is at Fin D (hidden). The engine 5 position is inboard.

Blackarrow
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Posts: 2783
From: Belfast, United Kingdom
Registered: Feb 2002

posted 01-21-2018 02:55 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
In the photograph, is that a man leaning against a ladder below and slightly to the left of the letter "C" ? If so, he provides some sense of scale.

SpaceAholic
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Posts: 4091
From: Sierra Vista, Arizona
Registered: Nov 1999

posted 01-21-2018 02:55 PM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by LM-12:
The command module main display console has five F-1 engine indicator lights on Panel 1.
Example (though this one configured for CM stacked on a Saturn IB):

LM-12
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From: Ontario, Canada
Registered: Oct 2010

posted 01-21-2018 03:16 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Blackarrow:
is that a man leaning against a ladder

Yes, I believe it is. Here is another view of SA-500F. Also, note that the B and C fin tips look damaged.

LM-12
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From: Ontario, Canada
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posted 01-21-2018 08:13 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
During the second stage S-II propulsion phase of the Apollo 13 launch, the center engine (number 5) cut off about two minutes earlier than planned. How was that early engine cut off seen by the crew on their LV ENGINES indicator?

That scene in the Apollo 13 movie shows the CM display console with the engines 1-4 lights illuminated and the center engine 5 light flashing on and off. Is that how the Apollo 13 crew saw their lights?

SpaceAholic
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From: Sierra Vista, Arizona
Registered: Nov 1999

posted 01-21-2018 08:51 PM     Click Here to See the Profile for SpaceAholic   Click Here to Email SpaceAholic     Edit/Delete Message   Reply w/Quote
Indicators 1-4 should be extinguished and 5 returned to "Yellow."

LM-12
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From: Ontario, Canada
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posted 01-22-2018 10:56 AM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
From the AS-506 (Apollo 11) launch vehicle flight evaluation report:
Engine startup sequence was nominal. A 1-2-2 start was planned and attained. Engine position starting order was 5, 1-3, 4-2.
The graph in Figure 5-2 on page 5-3 seems to show that engine 3 started slightly before engine 1, which would make the engine position starting order 5, 3-1, 4-2.

oly
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Posts: 256
From: Perth, Western Australia
Registered: Apr 2015

posted 01-22-2018 08:46 PM     Click Here to See the Profile for oly   Click Here to Email oly     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by LM-12:
...Figure 5-2 on page 5-3 seems to show that engine 3 started slightly before engine 1, which would make the engine position starting order 5, 3-1, 4-2.
The detail on this graph is not fine enough to make that call.

There was a ignition sequence start trigger that puts the start sequence into action that seems to show engine 5 engine buildup transients begin to register at about T-3.4 seconds, engine 1 and 3 begin to register just prior to T-3 seconds and engines 2 and 4 begin to register at about T-2.75 seconds however there is not enough resolution to determine the sequence of engine ignition between the paired engines.

What is shown is how impressive 50 year old technology was to sequence 5 huge rocket engines to ignite and accelerate to full thrust so accurately using automation considering all the steps, weight and quantity of fluids and gasses involved.

LM-12
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From: Ontario, Canada
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posted 01-24-2018 11:22 AM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
The "S-IC Stage Engine Startup Event Times" for Apollo 8 are shown in Table 5-1 in the AS-503 launch vehicle flight evaluation report. I did not see a similar table in the AS-506 report for Apollo 11, unfortunately.

mikej
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From: Germantown, WI USA
Registered: Jan 2004

posted 01-24-2018 05:42 PM     Click Here to See the Profile for mikej   Click Here to Email mikej     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by SpaceAholic:
Indicators 1-4 should be extinguished and 5 returned to "Yellow."
I have some information on both the Saturn IB and Saturn V version of the LV ENGINES subpanel on my website.

LM-12
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From: Ontario, Canada
Registered: Oct 2010

posted 01-24-2018 09:36 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
Apparently, the Apollo 6 command module also flew with the Saturn IB type LV ENGINES display. It can be seen in this 16mm onboard film of the control panel.

LM-12
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From: Ontario, Canada
Registered: Oct 2010

posted 01-25-2018 07:42 AM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
Or is that AS-202 footage and not Apollo 6?

mikej
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From: Germantown, WI USA
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posted 01-25-2018 06:40 PM     Click Here to See the Profile for mikej   Click Here to Email mikej     Edit/Delete Message   Reply w/Quote
While I cannot comment on the accuracy of the film's metadata, I seem to recall looking up Apollo 6's control panel when I did my Apollo 4 page and finding that it, too, had the Saturn IB LV ENGINES subpanel. (I couldn't immediately locate the document to which I referred at the time.)

I also took a look the full-res version of a photo I took of Apollo 6's control panel at Fernbank Science Center and confirmed that it has the Saturn IB indicator.

LM-12
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Posts: 2458
From: Ontario, Canada
Registered: Oct 2010

posted 01-25-2018 10:50 PM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
Some camera information from the press kits:

From the AS-202 Press Kit:

Four 16mm Milliken motion picture cameras will be mounted in the Command Module to record instruments, chute deployment and reentry. One camera will be mounted on the flat plate in the egress hatch (in the nose of the CM) to record jettisoning of the Apex cover, parachute deployment and reentry. The second camera is on a pallet where the right astronaut couch would be located, and will record liftoff and reentry through the right-hand window. Two instrument cameras, one on the left and one on the center, will record instruments and displays during the flight.
From the Apollo 6 Press Kit:
Two cameras will be mounted within the command module crew compartment. A 16mm Millikan motion picture camera will be pointed out the left rendezvous window. A 70mm Maurer still camera will photograph through the hatch window.

LM-12
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From: Ontario, Canada
Registered: Oct 2010

posted 01-26-2018 10:56 AM     Click Here to See the Profile for LM-12     Edit/Delete Message   Reply w/Quote
The Saturn-IB launch vehicle flight evaluation reports mention that the automatic ignition sequence scheduled the eight H-1 first-stage engines to start in pairs, with a 100 millisecond delay between each pair.

The engine pairs were 5-7, 6-8, 2-4 and 1-3.


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