Author Topic: Atlas Chronology  (Read 1609 times)

Offline Spaceman Spiff

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Atlas Chronology
« on: 10/31/2018 06:30 AM »
A lot has been written about the Atlas Missile en Atlas Launch Vehicle, including in these forums. And it deserves it, having played such an important role in the history of rockets and space travel.

There are different ways to look at history. In narrative form, telling the tale from its beginning, its origins, its evolution. Through the eyes of participants, who tell their own stories as they lived them. Through tables of launches and tests. Through technical specifications and their evolution and adaptation.

I have been working lately on presenting the history of the Atlas rocket (or at least a part of it) through chronology, a visual timeline. It puts the events and facts in a different format and, while limiting in certain areas, it gives a different perspective on what happened when. For example, through the timeline I noticed that  from 12 to 17 May 1959 all Cape Canaveral Atlas launch pads (LC-11, LC-12, LC-13 and LC-14) as well as launch pad 576A-2 at Vandenberg Air Force Base had Atlas missiles on them at the same time. Quite impressive.

It is of course a work in progress. Currently I have entered events roughly through April 1961. I will continue to add to it when time allows.

You can find the timeline here :http://www.wayo.be/atlas-rocket-history/

Of course I welcome all corrections, additions, references or other information.

- Michel -
- Michel -

Offline WallE

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Re: Atlas Chronology
« Reply #1 on: 10/31/2018 03:14 PM »
Here, I'll help fill out the remainder of 1961.

May: Three missile tests, no orbital Atlas launches this month. All flights successful.

June: Atlas 27E blew up on OSTF-1 at VAFB and badly damaged the facility, it was not used again for 10 months. This was the third and last Atlas lost to booster engine rough combustion at launch, afterwards copper baffles were phased into all Atlas booster engines. Two weeks later, Atlas 17E tumbled out of control and broke up 1-1/2 minutes into launch due to the pitch gyro motor running at half speed. No orbital launches this month.

July: Two successful missile tests. One orbital launch (Midas 3). On Midas 3's launch, the Atlas's programmer reset at staging due to an electrical problem, but no apparent ill effect resulted from this. The Mercury team looked into it anyway just in case.

August: Three launches. Two successful missile tests including the first Atlas F launch. Third was Ranger 1, which failed (but not due to any fault of the Atlas).

September: Three launches. The first was Atlas 26E, which lost sustainer thrust at staging. Immediate cause of the failure was unknown, later traced to spent propellant igniting at booster jettison and damaging plumbing. A few hours after 26E launched, Samos 3's Atlas-Agena blew up on the pad at Vandenberg when an umbilical disconnected too late, causing total loss of electrical power to the launch vehicle. Damage to facilities was not too bad and repair work was completed in just over a month. Third launch of the month was Mercury-Atlas 4 which verified the modifications made after MA-3.

October: Three launches, two successful ICBM tests and one space launch, Midas 4, which made it to orbit despite an Atlas roll control failure (but the mission largely failed due to the resultant incorrect orbit).

November: Six launches, four ICBM tests and two orbital. Atlas 32E was intended to carry a monkey on a suborbital lob, instead it ended up lobbing its passenger into the drink when the sustainer engine shut down at liftoff, after which a thrust section fired caused total loss of control and RSO destruction. An incorrectly installed regulator caused loss of LOX flow to the sustainer gas generator. Then Ranger 2 repeated the same Agena control problem that doomed its predecessor. Samos 4 (notably the first DoD launch to be completely classified and top secret) was lost due to a failure of the Atlas pitch control that put it in an incorrect flight vector that made orbital insertion impossible. Loss of the rate gyro head shield during flight was determined to be the culprit on this and Midas 4. Mercury-Atlas 5 successfully carried Enos the chimpanzee aloft, after which Atlas was considered to man-rated.

December: Six launches. Three were fully successful, one was a partial success, and Atlas 6F suffered a leak in the sustainer hydraulic system at staging, leading to premature shutdown. This flight was also carrying a monkey, although his capsule separated from the Atlas successfully, he was lost at sea when recovery crews were unable to locate it. The only orbital flight this month was Samos 5, which was put into an incorrect orbit due to a late Atlas sustainer cutoff. The film capsule was believed to have reentered and impacted in northwestern Canada but it was never found.
« Last Edit: 11/01/2018 02:36 AM by WallE »

Offline Spaceman Spiff

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Re: Atlas Chronology
« Reply #2 on: 10/31/2018 06:00 PM »
Great info! That second half of 1961 was interesting chronology wise too. No less than 4 days with two launches per day : Aug 23 (101D and 111D), Sep 9 (26E and 106D), Nov 22 (108D and 4F) and Nov 29 (93D and 53D). The year closes out with a salvo of 3 consecutive days with launches : Dec 20 (36E), 21 (6F) and 22 (114D). (All assuming UTC launch times).
That period will be added to the chronology shortly.

- Michel -

Offline WallE

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Re: Atlas Chronology
« Reply #3 on: 11/02/2018 03:03 PM »
Atlas 27E is a commonly seen failure in stock footage. As I'd mentioned, it was the third occurrence of destructive booster engine rough combustion on an Atlas launch. The B-1 engine malfunctioned almost immediately at ignition, a thrust section fire started from the LOX dome in the engine burning though, and the missile was completely destroyed at T+4 seconds when the propellant tanks exploded. Examination of debris found heavy damage to the B-1 injector head.

The other two episodes had been the back-to-back launch attempts of Atlas 51D and 48D in early 1960. On 51D, the Atlas lifted, the B-1 malfunctioned, and a major thrust section explosion occurred. This apparently caused loss of support pressure to the missile airframe, which collapsed and caused the entire load of propellants to mix in a huge fireball. LC-13 was heavily damaged and took six months to repair. Atlas 48D experienced a B-2 malfunction at ignition, but engine thrust had not yet reached 100% levels so the launcher did not release the missile. There was an explosion, and the missile sat there and burned for 60 seconds until the fuel tank went off. Damage was not as extensive as with 51D and it took only two months to repair LC-11 probably because the nature of the failure resulted in little to no propellant mixing.

The solution to rough combustion involved equipping the booster engines with copper baffles to prevent such phenomena as the racetrack effect when burning propellants would form a swirling vortex that produced shock waves that destroyed the injector head. This came at the price of about 40 pounds of added weight and some reduction in engine performance since the baffles covered some of the holes in the injector plate that propellants were sprayed through.

Curiously, I've never seen any aftermath photos of 27E except the one aerial shot on Silo World showing the blackened OSTF-1 with a booster engine laying some distance away. I have also never seen any video or film of 48D.

Offline Spaceman Spiff

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Re: Atlas Chronology
« Reply #4 on: 11/02/2018 09:11 PM »
After the 48D failure, for the following nine launches, a 4.25 second holddown delay was incorporated in order to verify engine stability before liftoff. Also a second redundant accelerometer was added to the Rough Combustion Cutoff system to increase reliability in case an accelerometer would fail. No booster instabilities were detected in the nine following flight although in the attempted launch of 32D the RCC in the sustainer engine was triggered, the engine was subsequently replaced and 32D had a successful flight. Of course 27E would show that the problem still existed.

I guess the 48D footage would resemble that of 9C which also burned on the pad for some time before exploding. Of course this was during a Flight Readiness Firing and not an actual launch.
- Michel -

Offline WallE

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Re: Atlas Chronology
« Reply #5 on: 11/02/2018 10:10 PM »
After the 48D failure, for the following nine launches, a 4.25 second holddown delay was incorporated in order to verify engine stability before liftoff. Also a second redundant accelerometer was added to the Rough Combustion Cutoff system to increase reliability in case an accelerometer would fail. No booster instabilities were detected in the nine following flight although in the attempted launch of 32D the RCC in the sustainer engine was triggered, the engine was subsequently replaced and 32D had a successful flight. Of course 27E would show that the problem still existed.

They also went back to using a wet start with the booster engines (that is, having the engine tubes filled with inert fluid as a shock damper). The specific reason for the rough combustion was not determined.

I guess the 48D footage would resemble that of 9C which also burned on the pad for some time before exploding. Of course this was during a Flight Readiness Firing and not an actual launch.

I read the postflight report for 48D and it gives a fairly detailed description of the events during the attempted launch. It was not as severe of a fire as what happened on 9C and was more erratic. An explosion erupted out the B-2 side of the missile, followed by automatic engine cutoff commands being issued due to turbopump overspeed. Fire burned for about 30 seconds before slowing down. Around 45 seconds, the fire started up again and continued until final missile explosion at 60 seconds. The fire on 9C was very hot and intense because it was fed by a ruptured LOX line, but on 48D it appears to have been mostly fuel rich.

9C also produced an incredibly powerful explosion that leveled the entire service tower on LC-12 because the propellant valves closed at engine cutoff and the pneumatic system opened the LOX boil-off valve to prevent tank overpressure. It kept venting pressure gas until the tank lost structural integrity and the intermediate bulkhead collapsed, causing the LOX to fall into the RP-1 tank and mix.

As I mentioned, 51D also suffered an airframe failure as a result of the thrust section explosion. It most likely ruptured helium bottles or plumbing in the pneumatic system, with the loss of support pressure, the whole thing crumpled up like a giant soda can and all the propellants mixed. Kaboom. On 48D however it seems that the final explosion started in the fuel tank and there was very little propellant mixing.

51D actually should not have lifted from the pad, but the RCC sensor in the B-1 engine was not working so it allowed the missile to be released anyway. The B-1 RCC sensor on 48D wasn't working either but the malfunction occurred in the B-2 so that engine's RCC operated correctly and terminated thrust before lifoff could be achieved.

Offline Jim

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Re: Atlas Chronology
« Reply #6 on: 11/02/2018 10:29 PM »

9C also produced an incredibly powerful explosion that leveled the entire service tower on LC-12

Umbilical tower.  The Service tower was unaffected.

Offline WallE

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Re: Atlas Chronology
« Reply #7 on: 11/03/2018 12:51 PM »
If I remember correctly the service tower sustained some minor damage from flying debris. The pad itself was a scene of total devastation--the concrete launch stand was caved in, the small whip umbilical towers leveled, and the top portion of the main umbilical tower, a one ton piece, was hurtled a couple hundred feet. Kerolox gel is powerful stuff. It took eight months to restore LC-12. They didn't bother rebuilding the large umbilical tower and replaced it with only a small one. The pad hosted a couple of D-series test flights and the second and third Atlas-Ables before being converted for the Atlas-Agena in early 1961.

Offline Spaceman Spiff

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Re: Atlas Chronology
« Reply #8 on: 11/03/2018 05:30 PM »
I read the postflight report for 48D and it gives a fairly detailed description of the events during the attempted launch.

The postflight reports contain a lot of interesting information. Unfortunately I haven't been able to find many of them. DTIC has a few but some are 'released to the public' but the text is not available on-line. Does anybody know another source for them ?
For the Atlas Timeline, after about 95D they are for the moment my only source for operational movements of the missiles (to/from the pad, hangars, etc.)

51D actually should not have lifted from the pad, but the RCC sensor in the B-1 engine was not working so it allowed the missile to be released anyway. The B-1 RCC sensor on 48D wasn't working either but the malfunction occurred in the B-2 so that engine's RCC operated correctly and terminated thrust before lifoff could be achieved.

That explains the reason why they added redundancy to the RCC accelerometers after 48D.
- Michel -

Offline WallE

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Re: Atlas Chronology
« Reply #9 on: 11/04/2018 09:25 AM »
Postflight reports that are online include 48D, 60D, 66D, 50D, 9C (the accident investigation report since that wasn't actually a launch), 93D, 13E, 26E, 32E, and 11F as well as a number of later NASA Atlas-Agena and Centaur launches. They're also all East Coast launches, I've never seen any reports for West Coast Atlas launches.

Except for 48D, they're all the "preliminary" reports which were issued three weeks after a launch and contain the basic rundown of events and flight data during the launch as well as a list of all Atlas East Coast launches to date. The full GD/A postflight evaluation reports were issued about a month after the launch. The 48D report has photos and graphs/charts of missile system performance data that aren't in the preliminary reports, and it doesn't have the list of Atlas launches to date.

And of course the reports for Atlas-Centaur AC-3, 4, and 6 are online but not 5 which is the one we really want.  ::)

Also the Wikipedia page on the Atlas D has an incorrect description of what dry/wet engine starts were. I've tried to fix it but some guy keeps reverting the page every time. I hate Wikipedia, I really do.

« Last Edit: 11/04/2018 03:03 PM by WallE »

Offline WallE

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Re: Atlas Chronology
« Reply #10 on: 11/08/2018 06:02 PM »
Mercury-Atlas 1 of course was the unsuccessful first attempt at launching a Mercury capsule (not counting Big Joe as that was a boilerplate capsule). Hidden behind dense clouds on a rain-soaked Friday morning, the Atlas suffered an apparent structural failure. The capsule transmitted data until impact in the ocean about 6 miles downrange. About 70% of it was recovered along with the Atlas booster engines and a section of plumbing for the LOX boil-off valve.

Aside from the weather preventing any visual coverage of the flight failure, telemetry data was also inadequate. Atlas 50D had only a single telemetry package with 50 measurements being taken in contrast to R&D Atlas missiles which had three telemetry packages. Telemetry indicated an entirely normal, uneventful launch until 57 seconds when a shock was registered in the forward portion of the missile followed by loss of measurements in that area. Fuel tank pressure went to zero followed by an erratic decay in LOX tank pressure. The ASIS system immediately responded by issuing a shutoff command to the propulsion system and a further shock was registered before complete loss of telemetry at 60 seconds. The abort was issued too early in the launch for the Mercury's parachute system to activate so it just pinwheeled its way down into the ocean.

The piece of LOX plumbing recovered from the Atlas had fatigue cracks in it and it was speculated that the forward portion of the LOX tank or the Mercury adapter had experienced aerodynamic bending while approaching the point of Max Q around the one minute mark that resulted in rupture of the Atlas tank section. Telemetry from the Atlas suggested a steady flight path until final loss of data, but this was questionable due to loss of measurements following the initial disturbance. The capsule's rate gyro measurements indicated that the stack may have pitched as much as 10 degrees.

A major redesign effort was undertaken for the rest of 1960 and involved equipping Mercury-Atlas vehicles with thicker tank skin. Also the lack of a launch escape system on MA-1 was suspected to have negatively affected the booster's aerodynamic profile. Future launches would have at least a dummy LES, the flight path was changed to be somewhat shallower to reduce loads, and clear skies were made a requirement to launch so there would be adequate camera coverage. Also after the last Atlas-Able experienced a similar failure caused by bending modes, GD/A began requiring all Atlas upper stage/payload combinations to be given proper structural dynamics testing.
« Last Edit: 11/08/2018 08:18 PM by WallE »

Online RIB

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Re: Atlas Chronology
« Reply #11 on: 11/08/2018 07:27 PM »
Interestingly enough, Big Joe, an unmanned Mercury prototype, made it through MAX-Q even though, the Atlas failed to stage. No escape tower on that Mercury-Atlas launch either.

Offline WallE

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Re: Atlas Chronology
« Reply #12 on: 11/08/2018 08:16 PM »
Interestingly enough, Big Joe, an unmanned Mercury prototype, made it through MAX-Q even though, the Atlas failed to stage. No escape tower on that Mercury-Atlas launch either.

Big Joe was a boilerplate capsule, it didn't have all the hardware of a full Mercury including the life support system and it would have weighed quite a bit less. The full capsule weighed around 3000 pounds. GD/A engineers had also opposed the idea of launching without an escape tower as they said it was needed for aerodynamic purposes. Ultimately the blame for the failure lay on Flight Director Walter Williams both for ordering the launch to take place without the LES and for launching it into cloudy weather where the booster couldn't be filmed after the first 20 or so seconds of flight (as well as depriving us of footage of what was probably a pretty cool explosion).

Had MA-1 succeeded, the next flight would have been an orbital MA-2 using Atlas 77D, but the postflight findings led to that vehicle being recalled and it was never flown.

47D through 52D were a pretty unlucky run of Atlases (49D aside).

Online RIB

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Re: Atlas Chronology
« Reply #13 on: 11/08/2018 09:52 PM »
 If poor  aerodynamics were the suspected cause of the MA-1 failure, then why did they Big Joe capsule, essentially the same shape as the MA-1 capsule (though lighter) make it through Max-Q? I understand they reshaped the trajectory after MA-1 but weren't the aerodynamic forces on the Big Joe shot essentially the same as the ones on the MA-1 shot. I don't understand how weight would affect the aerodynamics.  I understand the shape of the Mercury Capsule was different than the "standard" Atlas warhead, but I'm assuming that the weight of the Mercury capsule was LESS than the Atlas warhead, given the velocity requirements for an orbital vs a ballistic shot.

Offline WallE

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Re: Atlas Chronology
« Reply #14 on: 11/09/2018 12:02 AM »
Some warheads flown on Atlas were quite bulky, yes. The GE Mk2 RV was around the same weight as a Mercury capsule and the Mk4 flown on Atlas E/F was close to 4000 pounds.

What Mercury had and what Atlas warheads didn't was a hollow adapter section that was prone to vibrating under in-flight loads. There was that and the weight of the capsule pressing on the adapter and causing it to buckle. When the point of Max Q was attained, the shaking, vibrating adapter may have introduced loads into the Atlas's forward tank section that were too much for it to handle. If loads on the Atlas became 5% or greater than the internal tank pressure, it would fail under the stress. Owen Maynard also recalled that at that time, the entire situation of the adapter section and mating Mercury to the Atlas was a mess and nobody had really figured it out yet.

So capsule weight+hollow adapter section that vibrates in flight+poor aerodynamics due to no LES+possibly too steep flight trajectory=loading in excess of what the Atlas could handle.

Offline WallE

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Re: Atlas Chronology
« Reply #15 on: 11/11/2018 07:09 PM »
The first attempt to launch an Atlas D ended dramatically when Missile 3D lifted from LC-13 on the afternoon of April 14, 1959. The LOX fill and drain valve did not close at engine start and a pool of leaking LOX formed around the missile. Leakage from the fuel fill and drain valve also occurred, causing the propellants to mix and explode. The resultant loss of propellant flow and pressure caused an almost immediate 35% drop in B-2 engine thrust. Due to the imbalanced thrust, the Atlas pitched down and lifted in a rightward diagonal path instead of straight up. The B-2 launcher arm also failed to retract properly, but no apparent damage resulted from either the propellant explosion or the launcher arm.

The flight control system managed to retain a stable attitude until T+26 seconds when the booster section exploded and ripped away from the Atlas. At this point, the missile was in flames and no longer controllable--it began to sink back towards Earth and the flight was terminated by RSO action at T+35 seconds. The sustainer engine and verniers operated until final destruction. The major components of the Atlas landed about a quarter mile from the pad, which also sustained some minor damage from the abnormal liftoff.

The failure was determined to be caused by a failure of the butterfly valve acutator shaft in the LOX fill and drain valve, which was believed to have occurred at some point between the pre-flight readiness firing a few weeks earlier and the launch. The acutator shaft was changed to heavier but more durable steel on Atlas vehicles from 25D onward. The RP-1 leakage at liftoff was unrelated to the LOX valve problem, it was caused by ground crews neglecting to properly purge the launcher side of the RP-1 fill and drain line, which had about 25 pounds of fuel left in it.

Curiously, I've never seen an explanation given for the thrust section explosion in 26 seconds, but the LOX loss could have induced unstable combustion in the B-2 engine and caused it to fail in a similar manner to Atlas 27E et al.
« Last Edit: 11/11/2018 07:10 PM by WallE »

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