Author Topic: On-Pad Explosions  (Read 8155 times)

Offline Chrup4

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Re: On-Pad Explosions
« Reply #40 on: 09/05/2016 10:54 AM »
A factor in the rapid repair of the old IRBM and ICBM pads in the 60s was that these were top-priority national programs with unlimited funding, so spare pad hardware was stockpiled. Pad explosions were expected and planned for. Note how launch support equipment was well separated from the pads and protected by concrete blast walls (or the long-vanished 'Blockhouses"). Also, the RP-1 usually burned off quickly, so there usually was not thermal damage to the underlying concrete structure.

I had heard that the damage from Atlas AC-5 was mostly repaired in three months even though the next launch from LC-36A was not for over a year (probably more fire than structural damage). The Atlas-Centaur launch rate was small (only two during the time LC-36A was offline) and probably 36B alone was enough to handle it. Also while LC-13 was offline six months following Atlas 51D, some of that delay could have been due to converting the pad for Atlas E launches.

As for the RP-1 burning off quickly, you have to remember also that most of it doesn't actually go off in an explosion. Even on N1-5L, about 80% of the propellant load in the booster did not ignite and what did was mostly in the first stage. After the blockhouse crew were allowed outside, there were unburned droplets of RP-1 raining down from the sky. Despite the blast being intense enough to level the service towers and cave in the concrete launch stand, they still recovered most of the vital telemetry tapes intact from the rubble.

Offline kevin-rf

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Re: On-Pad Explosions
« Reply #41 on: 09/05/2016 11:00 AM »
Will Space X have to pay the bill for the repairs or is that the responsibility of the CCAFB?

Considering they are the ones who built and operate it, I would assume they (or insurance) has to not only pay for any pad repairs, but also any damage they inflicted on other people's equipment.
« Last Edit: 09/05/2016 11:02 AM by kevin-rf »
I just saw some idiot at the gym put a water bottle in the pringles holder on the treadmill.

Offline Chrup4

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Re: On-Pad Explosions
« Reply #42 on: 09/05/2016 02:25 PM »
Operation Fishbowl in 1962 involved a series of high altitude nuclear tests launched from Johnson Island in the Pacific on Thor IRBMs. After the "Bluegill" launch failed on June 2, the next attempt, code named Bluegill Prime, was made on July 25 but ended disastrously when the Thor caught fire on the pad. A stuck engine value cut the flow of LOX to the combustion chamber and RP-1 ignited on contact with the hot engine. The Range Safety Officer sent the destruct command and blew up the Thor on the pad, also destroying the nuclear warhead.

The pad area was extensively contaminated with plutonium and had to be cleaned up before the destroyed launch stand could be rebuilt.

Offline Jim

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Re: On-Pad Explosions
« Reply #43 on: 09/05/2016 03:25 PM »

SpaceX clearly thought pad explosions were a thing of the past, since the fueling and other support equipment was located close to the pad

Not really, they were protected by berms just like days of old.  They reused the existing Titan berms

You can see here

http://forum.nasaspaceflight.com/index.php?topic=40868.msg1578330#msg1578330
« Last Edit: 09/05/2016 03:32 PM by Jim »

Offline catdlr

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Re: On-Pad Explosions
« Reply #44 on: 09/05/2016 10:22 PM »
video of pad explosion of Atlas-Centuar AC-5 (video of explosion starts at 2:13)

Largest Explosion

https://www.youtube.com/watch?v=NgqnlUifggw?t=000

« Last Edit: 09/05/2016 10:24 PM by catdlr »
Tony De La Rosa

Offline MattMason

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Re: On-Pad Explosions
« Reply #45 on: 09/06/2016 04:02 AM »
Very fascinating series, Ed.

But what I'm taking away from this is why there were over 43 separate launch pads in the old days.

Blow one up? Go fly on another while you examine the charred, painted rocket pieces and rebuild the pad.

Took a while to rebuild pads, and it is only slightly faster today with light-gantry launches using strongbacks.
"Why is the logo on the side of a rocket so important?"
"So you can find the pieces." -Jim, the Steely Eyed

Offline Chrup4

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Re: On-Pad Explosions
« Reply #46 on: 09/06/2016 10:36 AM »
video of pad explosion of Atlas-Centuar AC-5 (video of explosion starts at 2:13)

Oddly enough, in all this time nobody's turned up the postflight launch reports for AC-1 or AC-5 although the reports for several early Centaur launches are online.

Offline Chrup4

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Re: On-Pad Explosions
« Reply #47 on: 09/06/2016 11:17 PM »
The final Titan I R&D launch was that of Missile V-4 from VABF's 395-A1 on the evening of May 1, 1963. In an ominous prediction of Atlas 45F five months later, the missile experienced a stuck engine valve that prevented the LR-87 engines from achieving sufficient thrust to lift the 110 ton missile, which then tipped over and exploded on impact with the ground. 395-A1 was repaired in two months and hosted Titan SM-7 on August 15.

I should add, I saw a video of Titan I V-4 on the net a long time ago. It was just like Atlas 45F--nighttime launch where the thing tipped over as soon as it was released. There's a closeup shot on the engines which are essentially not firing at all. I also once saw a brief clip of Redstone RS-3 on a Youtube rocket failure compilation. Otherwise most of those videos just have failures everyone's already seen hundreds of times like Juno AM-16, Atlas 27E, and Delta II 241.

Offline koroljow

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Re: On-Pad Explosions
« Reply #48 on: 03/12/2017 06:02 PM »
Samos 3 exploded on LC 1-1 at PALC on September 9, 1961. A pad umbilical did not detach at liftoff, which caused the Atlas-Agena B to switch from internal to external power. The engines shut down and the Atlas dropped back onto the pad and exploded in a huge fireball, resulting in the total loss of the photoreconnaissance satellite.

Pad damage was evidently not that bad as Samos 4 flew from LC 1-1 only nine weeks later.
Thanks for adding this one!   This was Atlas 106 D and Agena B A2201.  I have to date found no photos of the failure or its aftermath.  This could have been a more powerful explosion than Atlas-Able, the previous U.S. largest.  At the time, Atlas Agena B was the largest, most-powerful U.S. launch vehicle.  The next launch from Point Arguello LC 1-1 (later renamed VAFB SLC 3 West) took place on November 22, 1961.  It also failed, but not on the pad.

 - Ed Kyle

Sorry (again) for digging up an old thread.  But if someone (Ed?) ist still interested: this is the link to a video showing Atlas 106D's fate:


-Olaf-
Geschichte und Geschichten aus mehr als 5 Jahrzehnten Raumfahrt:
http://www.raumfahrtkalender.de

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