Author Topic: The Different Variants of Titan Boosters  (Read 37978 times)

Offline Vlong

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Re: The Different Variants of Titan Boosters
« Reply #200 on: 09/18/2016 11:36 PM »
On May 20, 1972, the fourth mission suffered an Agena pneumatic regulator failure during ascent that caused loss of control gas.  A stable orbit was not achieved.  Pieces of the highly classified satellite were subsequently found in England.  The eighth launch on June 26, 1973 ended in much more dramatic fashion when a Titan propellant tank ruptured only 12 seconds after liftoff.  Debris fell into the Pacific Ocean.  For decades, the cause of this failure was hidden.  I've never seen a photo or video of this failure.  Have you? Then again, Titan 24B's numerous successes were also hidden.  After the 1973 failure, 15 of them flew true before the program ended on April 17, 1984. Gambit-3's ground resolution, rumored to be the best ever achieved by the United States, remains classified.

The source for the June 1973 failure is that "History of GAMBIT/HEXAGON" article published by the NRO, however this other document I'm posting cites it as a rupture of the Agena fuel tank rather than the Titan, which seems more consistent with the fact that for years, the launch was always listed an an Agena failure.

Offline Blackstar

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Re: The Different Variants of Titan Boosters
« Reply #201 on: 09/20/2016 11:27 PM »
I'm kinda lazy at the moment, so I'll just ask:

How many Titan IIs were refurbished as SLVs in the latter 1980s? How many got launched? My understanding is that six were originally allocated to classified payloads (SIGINT satellites), but that this got reduced to three, leaving three to launch other payloads. One of those other payloads was Clementine.

Offline Jim

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Re: The Different Variants of Titan Boosters
« Reply #202 on: 09/20/2016 11:32 PM »
I'm kinda lazy at the moment, so I'll just ask:

How many Titan IIs were refurbished as SLVs in the latter 1980s? How many got launched? My understanding is that six were originally allocated to classified payloads (SIGINT satellites), but that this got reduced to three, leaving three to launch other payloads. One of those other payloads was Clementine.

13 flew, 14 produced
« Last Edit: 09/20/2016 11:33 PM by Jim »

Offline Skyrocket

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Re: The Different Variants of Titan Boosters
« Reply #203 on: 09/20/2016 11:38 PM »
I'm kinda lazy at the moment, so I'll just ask:

How many Titan IIs were refurbished as SLVs in the latter 1980s? How many got launched? My understanding is that six were originally allocated to classified payloads (SIGINT satellites), but that this got reduced to three, leaving three to launch other payloads. One of those other payloads was Clementine.

see here for all Titan-2 orbital missions: http://space.skyrocket.de/doc_lau/titan-2.htm
« Last Edit: 09/20/2016 11:38 PM by Skyrocket »

Offline Sam Ho

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Re: The Different Variants of Titan Boosters
« Reply #204 on: 09/20/2016 11:43 PM »
I'm kinda lazy at the moment, so I'll just ask:

How many Titan IIs were refurbished as SLVs in the latter 1980s? How many got launched? My understanding is that six were originally allocated to classified payloads (SIGINT satellites), but that this got reduced to three, leaving three to launch other payloads. One of those other payloads was Clementine.

13 flew, 14 produced
The unflown one is at the Evergreen Museum.

http://www.evergreenmuseum.org/popular-exhibits

Offline WallE

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Re: The Different Variants of Titan Boosters
« Reply #205 on: 05/01/2017 12:57 PM »
Years after the final Titan 3E launch, by TC-6 of Voyager 1 on September 5, 1977, JPL's Bruce Murray and others disclosed that the launch had resulted in a "close call".  The Titan 2nd stage had shut down a few seconds early due to a propellant management problem.  Something like 1,200 lbs of propellant "outage" occurred versus the goal of less than 534 lbs at most.  Centaur had to make up the velocity difference to the parking orbit.  It then consumed nearly all of its propellant during its final burn to reach its planned velocity.  In the end, Centaur had 3.4 seconds of propellant (less than 220 lbs) left in its tanks.

In the re-telling since, this story seems to have drifted a bit.  Some versions blame a Titan propellant leak.  Others say that the 1,200 lbs was the extra Centaur propellant burned.  Murray's book and NASA SP-2004-4230 both say it was 1,200 lbs left in the Titan tank and neither mention a leak. 

The Titan storable engines were "hydraulically balanced" and did not use active propellant utilization systems.  Propellant management was by statistical analysis that determined how much fuel and oxidizer should be loaded for given ambient temperatures and expected system performance (mixture ratios and tank pressures especially).  The goal was usually to run to oxidizer depletion with only 100 or 200 lbs of usable second stage fuel left as "outage".  The expected second stage propellant burn rate was 323.42 lbs/second, but this usually varied a bit.  Perhaps the TC-6 propellant loading was off for the conditions, or the engine mixture ratio shifted, or tank pressurization (autogenous) shifted.  I would love to see an official flight report to confirm the cause.

The version I heard was that the Titan second stage suffered from low thrust and was short on velocity at cutoff. This may have been due to a pressurization problem or perhaps the LR-91 engine used on TC-6 didn't have enough performance for the mission--individual rocket engines do vary slightly in their performance levels, as you noted, second stage performance on each Titan launch was a little different.

This was a recurring problem on Titan second stages; mostly Titan II ICBM tests, but a few orbital launches as well, for example one GAMBIT satellite was lost when its second stage underperformed and drove it into the Pacific Ocean. According to the flight report for the first Titan Centaur (TC-1), the second stage also underperformed slightly.

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