Author Topic: Atlas A Model ID  (Read 5306 times)

Offline RedTail48

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Atlas A Model ID
« on: 08/19/2017 01:02 am »
I recently bought the book "Project Mercury" by Eugen Reichl, translated from German into English. I'm puzzled by a photo on  page 11, purporting to be of "The very first launch of the Atlas ... June 11, 1957." It definitely seems to be an "A" model, but on the side are painted two confusing numbers which could be interpreted in various reversed or inverted ways - "51" or maybe "15." I don't have launch  photos of the "A's" which show such numbers... Can any of you sleuths help? By the way the Atlas photos on pages 83 and 103 are definitely printed reversed left-to-right, obvious from the side lettering. Sloppy!

Offline WallE

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Re: Atlas A Model ID
« Reply #1 on: 08/19/2017 01:16 am »
That's 10A, the fourth Atlas A launched and the first one with functional vernier engines (as well as the last with the interim 135,000 pound booster engines). Of the eight Atlas As flown, it was the nearest one to a completely perfect flight with no hardware glitches of significance.

Offline RedTail48

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Re: Atlas A Model ID
« Reply #2 on: 08/19/2017 03:02 am »
And do you think this photo also needs to be reversed left-to-right? And I wonder at what point the numbers on this photo were added? They're not visible on any of my pad photos of 10A, nor on the launch one, though they may have been on the opposite, non-visible side.

Offline Jim

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Re: Atlas A Model ID
« Reply #3 on: 08/19/2017 04:16 am »
It isn't 10A, since it can't be the back side
a.  The turbopump exhaust goes out the back side
b.  The pad ramp in is the foreground and hence it is the front side of the vehicle.
« Last Edit: 08/19/2017 04:26 am by Jim »

Offline cwr

Re: Atlas A Model ID
« Reply #4 on: 08/19/2017 05:35 am »
I recently bought the book "Project Mercury" by Eugen Reichl, translated from German into English. I'm puzzled by a photo on  page 11, purporting to be of "The very first launch of the Atlas ... June 11, 1957." It definitely seems to be an "A" model, but on the side are painted two confusing numbers which could be interpreted in various reversed or inverted ways - "51" or maybe "15." I don't have launch  photos of the "A's" which show such numbers... Can any of you sleuths help? By the way the Atlas photos on pages 83 and 103 are definitely printed reversed left-to-right, obvious from the side lettering. Sloppy!

I may not have understood your post correctly.
When I click on the image, the number that I see on the vehicle is 12 not 15.
That makes me suspect that this is 12A.

Of course that invokes another issue.
I have the launch of 12A as the 3rd Atlas A on 1957/12/17 at 1738 UTC and it is described as a successful limited range test where the engines fired for 2 minutes.
But I've seen other references that say the 1957/12/17 flight was 07A.

It's a long time since I captured that data, but hope it helps

Carl

Offline WallE

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Re: Atlas A Model ID
« Reply #5 on: 08/19/2017 05:56 am »
I may not have understood your post correctly.
When I click on the image, the number that I see on the vehicle is 12 not 15.
That makes me suspect that this is 12A.

It was definitely not 12A because 12A didn't have vernier engines and the paint pattern on the equipment pods was different. Only 10A and 11A had the pattern seen in the photo. The two are very hard to tell apart from launch photos especially since both flew from LC-12 on clear, cloudless days. 11A had the upgraded booster engines with the bell shaped thrust chambers, but you can't really see this in the photos.

10A was the first Atlas with verniers, which weren't steerable. 13A and 11A had fully steerable verniers, but failed due to aerodynamic heating shorting the autopilot control wiring, so they had to add insulation to it (those early test flights were sort of design-it-as-you-go-along).

I have the launch of 12A as the 3rd Atlas A on 1957/12/17 at 1738 UTC and it is described as a successful limited range test where the engines fired for 2 minutes.

Yes. 12A was the first successful Atlas flight.

But I've seen other references that say the 1957/12/17 flight was 07A.

7A was used for static testing at Point Loma, it wasn't a flight article missile.

Offline kevin-rf

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Re: Atlas A Model ID
« Reply #6 on: 08/19/2017 12:15 pm »
Not even close to an expert on this, but youtube videos of Atlas 10A and Atlas 13A do not appear to show numbers on the front side. Can only find a side view of Atlas 11A.

Atlas 10A:




Atlas 11A: (side view only)


Atlas 13A:


While silo world's image archive does not have a good front view of Atlas 11A, it does show that same tank trailer to the side of the pad: http://www.siloworld.net/MISSILE%20%20LAUNCHES/CAPE/Launches/atlas__a.htm

There is a higher quality copy of your image on the net.
Quote
Atlas missile launch (Febr. 20, 1958).
Original image caption: Cape Canaveral - February 20, 1958 -- The launch of a U.S. Air Force Atlas missile, test number 449, takes place from the Air Force Missile Test Center. (U.S. Air Force photo)
https://en.wikipedia.org/wiki/File:Atlas_missile_launch.jpg

https://upload.wikimedia.org/wikipedia/commons/9/90/Atlas_missile_launch.jpg

Edit: The date on the caption lines up with Atlas 11A
« Last Edit: 08/19/2017 12:20 pm by kevin-rf »
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Offline kevin-rf

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Re: Atlas A Model ID
« Reply #7 on: 08/19/2017 12:30 pm »
Not to beat a dead horse, but an Air Force archive seems to be the source: http://www.secretsdeclassified.af.mil/News/Photos/igphoto/2000593915/
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Offline edkyle99

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Re: Atlas A Model ID
« Reply #8 on: 08/19/2017 03:46 pm »
It isn't 10A, since it can't be the back side
a.  The turbopump exhaust goes out the back side
b.  The pad ramp in is the foreground and hence it is the front side of the vehicle.

Agreed.  It isn't 10A.  Peter Hunter has an image of the 10A launch showing this side of the rocket with no numbers visible. 

Nor is it 12A, which was launched on a cloudy day, according to Peter Hunter's photograph of that launch.

So why would the number "12" appear, and why so crudely applied?  LC 12?  The numbers appear to have been hastily applied at the last minute, since other photos taken in the days before this launch show no numbers.

This SDASM image I've linked below shows this launch to be that of Atlas 11A, which was launched on Feb 20, 1958, matching the USAF caption.  Note that this image is reversed.  It shows the number as a sort of "51", but the word "SECRET" on the image is reversed!
https://www.flickr.com/photos/sdasmarchives/17469896463/
https://www.flickr.com/photos/sdasmarchives/17469896463/sizes/l

Art LeBrun had this figured out as Atlas 11A a few years ago.  I'm not sure if he ever found out why the number "12" was painted on the side of the missile, however.

 - Ed Kyle
« Last Edit: 08/19/2017 09:24 pm by edkyle99 »

Offline RedTail48

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Re: Atlas A Model ID
« Reply #9 on: 08/20/2017 12:37 am »
Looks like it's 11A. Thanks everyone. Art spent a lot of time visiting the San Diego archives, borrowing negs and printing back at his place in southern LA. I had an interesting visit to his workplace, where Meade (I think) had their telescope assembly works. He, and Joel Powell (Canada) helped in a big way in clearing up confusing IDs on many photos in "our" collection.

Offline WallE

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Re: Atlas A Model ID
« Reply #10 on: 08/20/2017 06:10 pm »
Yes, as I said it's very hard to tell apart 10A and 11A, both were launched from LC-12 on cloudless days and both had the same paint scheme on the equipment pods. ID-ing the early R&D Atlas flights isn't difficult, a lot of the later VABF operational missile/RV tests and Atlas-Agenas are a lot harder and we don't even have photos of all of them.

Here's another, more complete video of 13A showing the missile breakup. You can see the flight path was different from 11A and it flew longer. Also unlike 11A, the thrust section is visibly on fire. This was because the B-2 turbopump disintegrated due to lube oil loss and probably tore up the thrust section, but it happened after engine shutdown due to missile tumbling, so had no real effect on the flight.

« Last Edit: 08/21/2017 06:32 am by WallE »

Offline WallE

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Re: Atlas A Model ID
« Reply #11 on: 08/21/2017 09:28 pm »
10A was to have been the third Atlas launched, after the postflight findings from 6A, it was taken down for modifications and ended up as flight #4. Here, we see the skirt covering the boattail being removed and the early-model Rocketdyne engines with the conical thrust chambers. The initial Thor and Jupiter flights also used these engines.

Other modifications made included adding filters to the autopilot to reduce in-flight vibration levels and a more substantial heat shield. The turbine exhaust was also changed to point outward and away from the boattail; in these pics, one can see that the original straight turbine exhaust is still present, I don't know when it was changed to the slanted exhaust.

One of the booster thrust chambers ruptured from combustion instability during an attempted FRF on 12/10/57, apparently because of ice or slush that had accumulated inside it. The thrust chamber was replaced and the first attempt to launch the missile six days later failed due to a leaking fuel valve. Launch was postponed until after New Year's, and when they tried again on 1/7/58, the same problem happened. Again the fuel valve was replaced and 10A finally lifted off on 1/10/58 for a perfect flight that tested out the vernier engines for the the first time.

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