Author Topic: Apollo Q&A  (Read 243947 times)

Offline the_other_Doug

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Re: Apollo Q&A
« Reply #340 on: 01/14/2018 02:28 am »
I had to get rid of the OP of the Moon Landing thread as he was given a chance, but his second post made me totally suspect he was a hoaxer. Not having any of those types on here. Saved the responses, removed quotes of his posts and merged them into here :)

Thanks for the explanation.  Had not bothered with the original thread, and this set of about ten responses here, not referencing any prior post, was awfully confusing until I got to this...
-Doug  (With my shield, not yet upon it)

Offline Timt64

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Re: Apollo Q&A
« Reply #341 on: 08/07/2018 03:08 pm »
Hi,
Were the EPS radiators on the J Mission CSM's upgrade/enlarged to accommodate the increased electrical load imposed by the sim bay equipment

Offline RIB

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Re: Apollo Q&A
« Reply #342 on: 08/07/2018 05:48 pm »
At the time of the Apollo 204 fire was the inward opening hatch on both the Block 1 and Block 2 command modules?

Offline Fequalsma

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Re: Apollo Q&A
« Reply #343 on: 09/08/2018 05:23 pm »
http://www.ninfinger.org/models/vault2012/Apollo%20CM%20Hatch%20Design.pdf

"The series of spacecraft designated Block II was designed for lunar orbit rendezvous and had an improved side access hatch system for extravehicular activity. The main difference between Block I and Block II was the heat shield hatch, which hinged outward for Block II and had latches with greater reach and pull-down capacity."

F=ma


At the time of the Apollo 204 fire was the inward opening hatch on both the Block 1 and Block 2 command modules?

Offline penguin44

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Re: Apollo Q&A
« Reply #344 on: 06/17/2019 04:55 am »
Why did apollo 11 Jettison the LM while still in lunar orbit? What if the sps on the sm didn't light?

Offline MATTBLAK

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Re: Apollo Q&A
« Reply #345 on: 06/17/2019 06:28 am »
There would not have been enough propellant left in the Ascent Stage to push both vehicles into Trans Earth Injection. The SPS engine was very necessary to initiate the Trans-Earth Injection burn. If the TEI SPS burn terminated early for some reason, there were very few scenarios where the RCS system could make up the necessary delta-v to get them on course for even a slow, low energy return to Earth.
« Last Edit: 06/17/2019 06:32 am by MATTBLAK »
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Offline penguin44

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Re: Apollo Q&A
« Reply #346 on: 06/17/2019 08:17 pm »
Good to know, thanks!

Offline joema

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Re: Apollo Q&A
« Reply #347 on: 10/23/2019 05:08 pm »
There would not have been enough propellant left in the Ascent Stage to push both vehicles into Trans Earth Injection. The SPS engine was very necessary to initiate the Trans-Earth Injection burn. If the TEI SPS burn terminated early for some reason, there were very few scenarios where the RCS system could make up the necessary delta-v to get them on course for even a slow, low energy return to Earth.

This is correct, largely because the CSM RCS used separate propellant tanks from the SPS and cross-feed was not available. According to a Howard Tindall memo dated 4-8-68, the total available CSM delta-V via RCS was 150 feet per sec.

As a side note, in the fictional Martin Caiden book "Marooned" the CSM stranded in earth orbit due to SPS failure could not de-orbit using RCS because of insufficient propellant. This was actually technically plausible since the SM RCS did not have propellant cross feed. Depending on altitude and orbital parameters a 200-300 ft/sec retro burn was needed.

By contrast the LM could cross feed ascent stage propellant tanks to the RCS and in some lunar ascent contingency situations a large delta-V was theoretically achievable via RCS alone.

In a memo dated 10-29-69, Howard Tindall said if the APS quit early and could not be restarted, up to 1,000 feet per sec. might be achieved with RCS alone. This would have required a nine minute RCS burn which far exceeded the nominal continuous limit of 85 sec, however they felt it was possible.

Prior to Apollo 11, there was a significant concern over sustained RCS plume impingement on the LM body, and some of the RCS constraints were based on that. Starting with 11 they used plume deflectors so that issue was lessened. There were still nominal duty cycle and continuous burn limits due to possible valve and nozzle corrosion and thermal factors, but apparently they felt in a contingency ascent case a nine minute continuous +Z LM RCS burn was possible.

The LM and SM RCS looked alike but the LM thrusters were made by Marquardt and the SM RCS by Rocketdyne, so maybe there were differences.

In any event, there was inadequate CSM RCS propellant available for a TEI burn. Likewise after achieving lunar orbit there was almost no LM ascent stage propellant available, whether used by the APS or RCS.

Offline libra

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Re: Apollo Q&A
« Reply #348 on: 01/16/2020 10:57 am »
While the Block II CSM serials were impeccable and most vehicles were build and flown - the Block I numbering looks like a total mess.
https://space.skyrocket.de/doc_sdat/apollo-csm.htm
So we have a 009, 0011, 0012, 0014 (dismantled for Apollo 1 inquiry)  0017 and 0020.
Well then, how many Block I CSM was NAR supposed to build in 1963-64 ? and what happened to the "holes" in the sequence ? CSMs 0010, 0013, 0015, 0016, 0018, 0019 ? Anything build before 009 ?
The boilerplates were BP- numbers, are they part of that list ?

Thanks in advance !

Offline Proponent

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Re: Apollo Q&A
« Reply #349 on: 01/16/2020 02:23 pm »
Thanks in advance !

That's an interesting suggestion, but I believe there was both a CSM-012 and a BP-12, flown on a Little Joe II:  see the last attachment to this post.

Your question made me wonder whether boilerplates and mock-ups shared a numbering sequence, but that does not pan out, as numbers 6 and 13 were used for both (see attachments to the present post).

Offline GClark

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Re: Apollo Q&A
« Reply #350 on: 01/17/2020 02:28 pm »
While the Block II CSM serials were impeccable and most vehicles were build and flown - the Block I numbering looks like a total mess.
https://space.skyrocket.de/doc_sdat/apollo-csm.htm
So we have a 009, 0011, 0012, 0014 (dismantled for Apollo 1 inquiry)  0017 and 0020.
Well then, how many Block I CSM was NAR supposed to build in 1963-64 ? and what happened to the "holes" in the sequence ? CSMs 0010, 0013, 0015, 0016, 0018, 0019 ? Anything build before 009 ?
The boilerplates were BP- numbers, are they part of that list ?

Thanks in advance !

This document can answer some of your questions.

https://www.ibiblio.org/apollo/hrst/archive/1690.pdf

Offline libra

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Re: Apollo Q&A
« Reply #351 on: 01/19/2020 10:01 am »
thank you.

I found this browing Google books. It is a montage from a NASA hearings document.

I'm left wondering, what happened to CSM-013, CSM-015, CSM-016, CSM-018, and CSM-019.


Offline whitelancer64

Re: Apollo Q&A
« Reply #352 on: 01/23/2020 03:30 pm »
thank you.

I found this browing Google books. It is a montage from a NASA hearings document.

I'm left wondering, what happened to CSM-013, CSM-015, CSM-016, CSM-018, and CSM-019.

This is the extent of what my google-fu can tell: the designations CSM-013, and CSM-015 were sometimes used to describe boilerplate spacecraft used in the Saturn I flight tests in 1964 and 1965. Far more often they were called BP-13, and BP-15.

I suppose it is possible that the prior use of those designations may have precluded their use for the Block I Apollo spacecraft, though I have found no sources which state this.

What I think is more likely: several Block I spacecraft were cancelled, and those designators may have been slated for those cancelled vehicles.
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Offline libra

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Re: Apollo Q&A
« Reply #353 on: 01/23/2020 06:43 pm »
Thank you very much. Very interesting.

Offline Orbiter

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Re: Apollo Q&A
« Reply #354 on: 05/26/2020 03:37 pm »
Related to DM-2: What were the downrange abort constraints as far as weather went for Apollo?
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Offline the_other_Doug

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Re: Apollo Q&A
« Reply #355 on: 05/30/2020 12:57 am »
IIRC, the downrange abort area weather constraints were less severe in Apollo because, with multiple stages and an SPS engine available, you could do a lot of maneuvering to steer to a good-weather area once you were past Mode I, LES aborts.

An LES abort -- firing the tower -- gives you no choices as to where you'll land, you'll follow a ballistic trajectory defined by the point where the abort was initiated, and the point where the LES rockets are spent.  That range of aborts defined a roughly rectangular box extending downrange maybe a couple of hundred km.  That area, the primary abort range, had to have weather good enough for spacecraft recovery.

Once the LES tower had separated, aborts involved guiding the splash point using either a staging from stage 2 to 3, or staging the CSM from the stack entirely.  There were several combinations of factors, but in each case you could fire the S-IVB and/or the SPS engine to aim for a primary trans-Atlantic abort zone, or even (if far enough along) a very long suborbital abort to a Pacific splashdown.

So, if the Mode I abort zone had acceptable weather, you usually had a place along the flight path to which you could steer your abort landing, with an Apollo launching on a Saturn V.

Later in the Saturn V boost phase, they stopped worrying about abort landing zones and adopted an abort-to-orbit profile, where at a given point in the second stage burn you had enough energy that you could stage off the S-II and, with a good S-IVB, you could stage off of it and use the SPS to achieve a stable orbit.  That at least let you select exactly where in the world you wanted to land.  That was called S-IVB to COI (Command Orbit Insertion).  Further into the S-II burn, you got to where the S-IVB, by using all of its propellants, could put the stack into orbit.  That was called S-IVB to orbit.

Short answer, they only worried about the first couple hundred km of the flight path for good recovery weather, after that they targeted recovery areas with acceptable weather and had more flexibility because of the combination of stages available for use in Mode II and beyond aborts.
-Doug  (With my shield, not yet upon it)

Offline Jorge

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Re: Apollo Q&A
« Reply #356 on: 05/30/2020 01:21 am »
Related to DM-2: What were the downrange abort constraints as far as weather went for Apollo?

Also Apollo used low inclination trajectories. The launch azimuth was limited to the 72-108 degree range, which limited inclination to 33.3 degrees. So the groundtrack avoided the north Atlantic. Only Skylab (50 degree inclination) and ASTP (51.6 degree inclination) even had to worry about the north Atlantic.
JRF

Offline Citabria

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Re: Apollo Q&A
« Reply #357 on: 10/05/2020 01:29 pm »
It's well known that control of Apollo-Saturn missions transferred from the Launch Control Center at Kennedy to Mission Control Houston upon tower clear. But the LCC's role did not just end right then, did it? What flight roles did the LCC play after tower clear? Did they process launch telemetry and send it on to Houston or Goddard? Did they stay active in a support role through the last Saturn S-IVB operations?

Offline edkyle99

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Re: Apollo Q&A
« Reply #358 on: 10/05/2020 02:52 pm »
It's well known that control of Apollo-Saturn missions transferred from the Launch Control Center at Kennedy to Mission Control Houston upon tower clear. But the LCC's role did not just end right then, did it? What flight roles did the LCC play after tower clear? Did they process launch telemetry and send it on to Houston or Goddard? Did they stay active in a support role through the last Saturn S-IVB operations?
Tracking and telemetry was handled outside of the LCC.  In Florida at the time there was MILA on Merritt Island and STADAN based in Fort Myers, which were part of the Manned Space Flight Network.  My guess is that only a few controllers stayed active in the LCC after T-0, those being the folks who safed and shut down the ground systems.   Houston controlled the S-IVB after liftoff. 

Saturn V Flight Manuals had this description, which talks about CIF, something not mentioned above.  See https://en.wikipedia.org/wiki/Central_Instrumentation_Facility  When I worked at KSC during the 1980s, CIF was just being phased out, an odd looking building topped by numerous big antennas.  Many of its functions were consolidated at the LCC.

"Kennedy Space Center, Cape Kennedy, Florida. The space vehicle is assembled and launched from this facility.  Prelaunch, launch, and powered flight data are collected by the Central Instrumentation Facility (CIF) at KSC from the launch pads, CIF receivers, Merritt Island Launch Area (MILA), and the downrange Air Force Eastern Test Range (AFETR) stations. This data is transmitted to MCC via the Apollo Launch Data System (ALDS). Also located at KSC is the Impact Predictor (IP)."

 - Ed Kyle   
« Last Edit: 10/05/2020 03:34 pm by edkyle99 »

Offline Citabria

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Re: Apollo Q&A
« Reply #359 on: 10/05/2020 07:31 pm »
Thanks. So the LCC used mainly hard-wired signals as described in Ch. 16 of https://www.hq.nasa.gov/office/pao/History/SP-4204/contents.html.

So how did they control the launch after T-0 when the umbilicals came out? They must have received telemetry too, at least until T+10 or tower clear.

 

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