APOLLO15; STAGING ANOMALY

A little-known staging anomaly took place on Apollo 15 (AS-510). When I read about it in the AS-510 launch report I nearly fell out of my seat and recently while watching news video of the launch I saw another piece of the puzzle. The following is an excerpt from my book, “Growing up with Spaceflight-Apollo Part Two” concerning the launch anomaly plus a lot of details not included in the book, especially that final piece of the puzzle; the secondary plume!

The whole story is in HERE

“Boosting Apollo 15 was a Saturn V quite a bit different from the vehicle that had boosted Apollo 14. Nearly all of the changes in the launch vehicle monikered as AS-510, had been made to save weight and add payload capability. Most apparent from the external perspective was the absence of the four ullage motors that had previously been located at 90 degree intervals around the skirt that attached the S-IC first stage to the S-II second stage.

“Those four solid propellant rocket motors were designed to fire .5 seconds after shutdown of the first stage as triggered by the Saturn V’s Instrument Unit (IU). Then .2 seconds later the IU commanded the firing of the shaped charges that would separate the first and second stages. The Ullage motors would continue to burn for a total of about 3.87 seconds producing about 22,900 pounds of thrust each. The objective of the motors was to apply a continued acceleration to the S-II stage and thus seat the fuel and oxidizer in the bottoms of their tanks. Data from past flights indicated that those four Ullage motors were not needed, so they were deleted from all future Saturn V launch vehicles beginning with AS-510. Internally, the S-II stage had another ullage system change when fixed orifices replaced its ullage pressure regulators.

“Meanwhile, down on the huge S-IC first stage, four of the eight solid-fuel retro rockets were deleted. The retro rockets aided the separation of the stages by countering any residual impulse from the spooling down of the F-1 engines and helped to counter the stage’s inertia. Data indicated that four retro rockets could do the job as easily as eight. Additionally the F-1 engines were “reorificed” beginning with AS-510 bringing the Saturn V’s total thrust up from 7.5 million pounds to 7.68 million pounds. All of these changes, although sounding somewhat large, only increased AS-510’s payload capability by 1,410 pounds, but 400 of those extra pounds allowed the Lunar Rover to ride to the Moon.

“At 136 seconds into first stage burn, the IU commanded the center engine on AS-510 to shut down. Then, 22.56 seconds later the IU commanded the outboard engines to shut down and the staging sequence to begin. It was at this point that the concept of eliminating four of the eight S-IC retro rockets and those four ullage motors nearly bit NASA in the butt. The problem began with the “shutdown” of those new up-rated F-1 engines.

“For those of you reading who are not familiar with turbine engines (and engineers reading please excuse me for simplifying), when you shut down a high-speed turbine, you do not just stop it suddenly. Doing so would cause the turbine’s own inertia to rip itself apart and it would explode like a fragmentation bomb- sending chunks of shrapnel flying in all directions at very high velocity. The F-1 engine had at its heart ultra high-speed turbines pumping fuel and oxidizer. In order to safely shut it down, the ignition source was removed and it was allowed to “tail-off” or spool down to an eventual stop while LOX and RP-1 continued for a time to flow through it. That outflow was still at a fairly high rate and caused some residual impulse.

“In the case of AS-510 the engine tail-off of the outboards lasted longer and was of a greater residual impulse than experienced from analysis of the previous version of the F-1 by 10.8 %. To compound the problem the elimination of the four ullage motors on the interstage skirt subtracted 91,600 pounds of S-II stage posigrade thrust as well. Normally, with an eight retro rocket and four ullage motor staging, the S-IC and the S-II stages would be slightly over 100 feet apart by the time the five J-2 engines in the S-II came up to full thrust.

“Predicted separation with just four retro rockets and no ullage motors was just short of 70 feet. In reality the separation distance of the two stages on AS-510 at full S-II thrust was just short of 40 feet!

“In fact when the plume of the S-II engines contacted the S-IC it was so powerful that it knocked out the telemetry being transmitted from the departing stage. The Radio Frequency (RF) signal continued, but the antenna gain was muted. Such RF signals without gain would indicate that the cable bundles had been blown away, or that the RF canister itself had been damaged or blown away. This loss had no impact on the mission since the S-IC had already been jettisoned.

“The real alarm was sounded after the mission at MSFC when it was calculated that if one of the four S-IC retro rockets had failed to ignite the two stages could have re-contacted during the staging sequence. That would have resulted in a catastrophic failure of the S-II and a mission abort using the escape tower. It was immediately decided that the four retro rockets that had been deleted from the S-IC would be reinstated for the next mission; Apollo 16.”

Now- here is the part that I could not put into the “Growing up with Spaceflight- Apollo Part Two” book, because there is no NASA documentation to prove it, there is only my own comparison of TV video.

So violent was the close proximity ignition of the five J-2 engines of the S-II stage that not only did it wipe out the telemetry RF units but it also ruptured the LOX tank dome on the S-IC stage. This is clearly seen in the staging footage as a secondary plume erupts from the S-IC that is not seen on any other Saturn V staging. In order to prove this I watched the staging videos from all of the Saturn V stagings where the event can be seen (Apollos 9, 12 and Skylab 1 were obscured by weather and Apollo 17 was a night launch so no plume was visible) and none have the brief secondary plume.

At staging there was 31,135 pounds of residual LOX in the tank, under pressure. At that point the S-IC was ~72Km or 44 miles in altitude and well outside of most of the earth’s atmosphere. The release of 31,135 pounds of LOX could easily account for the secondary plume seen in the video. That would mean that the upper LOX tank dome was compromised by the staging event.

Presented here is a side-by-side of the Apollo 14 staging sequence and the Apollo 15 sequence. The images are matched frame-by frame so you can see the difference.

That said, the crew was not really in any danger. The departing LOX, as seen in the ground and flight tests for SA-2 and 3, simply turned to ice crystals instantaneously. It could not burn or explode, because there was no fuel to combust. Instead what it did was to expel outward and very rapidly down the side of the S-IC and away from the departing S-II and Apollo spacecraft. Although the close proximity of the staging did wake up the engineers when the post-flight data was reviewed, in aviation we have a saying about vehicles moving too close to one another: “As long as you don’t get into those negative inches, there’s no problem.”

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SKYLAB'S MONIKERS

Ever wonder why the Skylab mission patches and the mission number don't seem to match? Well here's the complete explanation quoted from my book "Growing up with Spaceflight, Skylab/ASTP"

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When the missions for Skylab were first being finalized it had been decided that the launch of the workshop would be called “Skylab I” and the three crew launches were to be given monikers of Skylab II, III and IV, or SL-2, 3 and 4.

As the program progressed, however, someone in NASA management decided to re-designate the manned missions as SLM-1, 2 and 3. Thus, when it came time to make the mission patches there was some confusion as to which number should be applied to which mission. The crews were told that they should use 1, 2 and 3 to designate their individual missions and the process moved ahead with artwork being done for patches and stickers all using 1, 2 or 3.

As launch dates drew near, NASA management, of course, decided to change that decision back, drop the “M” from the manned missions and, again, number the Saturn V launch as “Skylab-1” and the manned flights as 2, 3 and 4.

Unfortunately, it was far too late for the mission patches and other items already branded with those numerals. So, Skylab 2 launched with a patch that said “I” and Skylab 3 launched with a patch that said “II” and so on. This confused the hell out of the news media as the Skylab 3 launch approached. They were given a press kit for the second manned mission that said “Skylab 3” on it, but were given mission patches, stickers, mugs, and assorted other mission items that said “Skylab II.” They did not know what in the world to call the mission! NASA, however, managed to side-step the problem by simply referring to the mission as “Skylab.” You may note that in this text we will use the original designations of Skylab 1, 2, 3 and 4. In aerospace it is always simpler to avoid management decisions in the first place.

By the way, the wives of the Skylab 3 astronauts had a secret mission patch of their own created that spoofed the one that their husbands were wearing.

COOL Videos and stuff area

This is the section for assorted cool videos and stuff

Some folks post their cool photos, videos and drawings on FaceBook,  but there is a catch. You see when you post a photo on FaceBook you give licence to everyone else on that site to use your photo any way they wish anyplace on that web site. I prefer to control my own photos. So, you are welcome to see my cool photos and stuff here... where I still own them. All photos and images here are copyright Wes Oleszewski and all right are reserved.

 WHAT I WAS DOING ON THIS NIGHT, JULY 25th, 1971
THE EVE OF THE APOLLO 15 LAUNCH

"SHERIDAN PARK, WE HAVE A PROBLEM!"

(From Growing up with Spaceflight- Apollo Part Two")

"Late into the evening prior to launch-day I decided to do a flight readiness test of my recording equipment. Suddenly- A GLITCH! My, or rather- my sister's, external microphone had failed! This was before they started putting built-in microphones on recorders- so I was really screwed. It was 9:45 at night- there wasn't a store in the Saginaw Valley that was open- especially not one with a microphone. Worse yet, I had spent my last dime on the tapes! I scrambled for a solution. Wiggle the wires... no use. Tap on it- no good. Take it apart... now it's REALLY busted! Sheridan Park- we have a problem!

 Perhaps, I pondered, when the store opens at 9:00 in the morning, I could get there and, after negotiating some sort of a lawns-to-be-cut-later deal with my parents, I could buy a new microphone, and make it back home within the 26 minutes between the time the store opens and the launch takes place... okay... that was nuts. There was no way that was going to happen, just the negotiating the lawn-cutting part with my parents alone was on a par with negotiating with North Vietnam. I sat there looking at the disassembled microphone and I thought "What would Gene Kranz do?" Simple- he'd call a meeting of his engineers and controllers and he would tell them to go out and find a solution to the problem with what they had.

 With what they had... hummm...

It was then that the thought struck me that several months back I had accidentally stuck an earphone into the microphone jack and it fit; in those days both had 1/8 inch jacks. And an earphone had the same basic elements to it as the microphone that was now laying in pieces in front of me. I knew that because I had dissected plenty of earphones. In short order I was rooting through the family “junk drawers” and had scrounged up an earphone that I had not yet dissected.

I tested it in the microphone jack; IT WORKED!

Sure the sound had a lot of tin in it and some 60 Hz hum, but it recorded! Using a four inch by six inch railroad “pounding card” that Dad had brought home from work, some masking tape and a hand full of tissues I had a microphone that the boys in the backroom at Houston would be proud of. I added a small measuring stick to give me the optimum distance from the TV speaker and I was "Go for the launch of Apollo 15!"

Copyright 2014 Wes Oleszewski- all rights reserved

THE COOLEST OPENING THEME EVER (IMO)

In my opinion the coolest opening TV theme for any Apollo flight was the NBC one for Apollo 15.

So, after more than a decade of searching, I now have a copy of it. Here it is...

(In keeping with the "Internet Users Who Are Occasionally Dense Act of 2009" we now advise you to click on the video and NOT the picture of the TV set. Thank you.)

By the way... my second book on spaceflight, Growing up with Spaceflight- Apollo Part Two can how be had in both eBook and PRINT! Get your print version today... because this one has Apollo 15 in it, as well as Apollos 14, 16 and 17.

Growing up with Spaceflight- Apollo Part Two, paperback

THE DAY OF THE APOLLO 11 LAUNCH

Here is a sample of my account of the Apollo 11 mission and this is how we saw it back in 1969

It was a fine summer morning in Saginaw, Michigan on the 16th day of July, 1969 and by nine o'clock that morning, most of us kids had already been outside playing for a while. I had no idea that the events that were up-coming would have a profound effect on my life. Sure, I'd been told a zillion times that history would be made that day, but in the mind of a 12- year- old, that meant little.

There was no escaping the TV coverage of the Apollo 11 mission as all of the networks had been on the air live since before dawn. Bergman did some of his best space savvy droning on ABC in contrast to the outward disdain for the space program presented by Chet Huntley and his otherwise indifferent partner David Brinkley on NBC. Over on CBS they had pulled out all of the plugs for this mission. Cronkite had been teamed up for the first time with astronaut Wally Schirra in pairing that would become nearly as legendary as the flights they would cover.

All three networks ran the standard clips of the astronauts, eating, suiting up and walking out... although a close look at the suit-up video would have revealed that the event shown was actually taped during the Countdown Demonstration Test back in the first week of June. The tell-tale clue to that is the fact that in the "suit-up" footage, the astronaut's suits are missing the Apollo 11 mission patch.

My Mom called me to the TV less than two minutes before Apollo 11 lifted off. At the time I had watched, with a growing kid's interest, all of the previous flights. In my mind, NASA could do anything. Now I stood by the TV and watched as Apollo 11 counted down to zero. The images of the Saturn V roaring to life were now, for me, as familiar as were the images of the ascent and staging. I recall that as Apollo 11 cleared the tower, my Mom said,

"Oh God... they're taking such an awful chance."

Looking at her I said to myself "What chance?" I thought that NASA had this all planned out so completely that every detail was covered. I recall feeling that my Mom's concern just showed that she did not understand how good NASA was at doing this. When the coverage showed Apollo 11 in Earth orbit, I went back outside to play.

I went back to my room that evening and got out my model CSM and LEM that I had built with my remedial modeling skills. I practiced some docking and undocking and did a lunar landing on my bedroom floor. For the first time in my 12 years of life, I recall having the strong desire to find out, not just more, but a lot more about Apollo and spaceflight in general. I wanted to do so before the astronauts, now headed toward the moon, arrived there.

The complete account of  Apollo 11, as well as Apollos 7,8,9,10,12 and 13 can be found in my book. It is available in hard copy or in e-book form at the following links:

Growing up with Spaceflight- Apollo Part One- print version




Growing up with Spaceflight- Apollo Part One- eBook











A PART OF APOLLO/SOYUZ THAT YOU DIDN'T SEE
This video contains a segment of the Apollo/Soyuz launch day that you probably have not seen. Tom Stafford had a lot of trouble approaching the S-IVB as the sun glare off of the Pacific Ocean was so bright that it blotted out his COAS (Crew Optical Alignment Sight).
CAUTION: This clip is rated "PG" for language- Pilot guidance is advised...

Here is a short video about the fiber optics and the camera pods...

(Photos: Space World Magazine and NASA)

If you like this sort of detailed stuff, check out my book series "Growing up with Spaceflight"

You can't miss 'em, they're shamelessly splattered all over this blog.
Growing up with Spaceflight






"WE CAME IN PEACE"

"Don't you ever bring that book to this classroom again!"

This is a sample from Growing up with Spaceflight- Apollo Part One:

"Several weeks after the Apollo 11 splashdown, my Dad stopped into a Gulf station for gas. He came back from paying and he handed me something- it was a book. When I opened that book, titled "We Came In Peace," it was as if someone had injected liquid hydrogen into the sparks of my new-found spaceflight passion. Even looking at the publication today, it is likely one of the finest illustrated and composed presentations of the nuts and bolts of the effort to get to the moon and space in general that had ever been produced up to that time. Yet, it was sold at gas stations! All of the other spaceflight books in my school’s library were illustrated with early representations of von Braun’s 1950s exploration plans or Project Mercury missions with looks “forward” to Project Gemini, but this book was about Apollo and it was up-to-date. The book was free if you “filled up,” but my Dad rarely filled the car up with gas. Instead, along with his “dollar’s worth” of gas that he normally bought, he probably paid the full price for the book; that price was one dollar.

I lived in that book to the point where my sixth grade teacher told me never to bring it to school again."

Here is the CBS opening for Apollo 15

Here is the CBS News intro for the Apollo 15 mission:

To get you copy delivered signed and personalized Click HERE

My story of the Apollo 15 mission can be found here; in Growing up with Spaceflight- Apollo Part Two. The book can be found exclusively on Amazon Kindle.

APOLLO PART TWO: eBook version

COULD SNOOPY LAND ON THE MOON?

No matter when the subject of Apollo 10 comes up, space-buffs always seem to ask the question as to if or not the Apollo 10 crew could have landed on the moon and been first.

Dubbed the “dress rehearsal” Apollo 10 was much more; it was a critical step toward mankind’s first landing on the lunar surface. The media, however, seemed relentless in their efforts to portray Apollo 10 as an excess step leading up to Apollo 11. Even the use of Pad 39B was slanted as somehow being frivolous. The fact was there were plenty of navigation, communication and hardware issues that needed to be explored and solved before a landing attempt could be made. Even Cronkite speculated that considering Stafford and Cernan were going to be just 50,000 feet above the lunar surface, perhaps they may be tempted to. “…just ease her down and be the first ones to land…”

Thus, to this day the question is still batted about as to if the crew could have "pulled a fast one" and just landed SNOOPY and the correct and simple answer is, "No."

The cold hard fact was that SNOOPY, LEM 4, which the crew would be flying, had not gone through Grumman’s Super Weight Improvement Program also known as SWIP. That program saw NASA offering a bonus of $10,000 for every pound that could be scrubbed off of a LEM. Of course that meant that a clever Grumman engineer could have made a cool $1.85 million if he could have figured a way for Stafford to not take Cernan along. The first vehicle to go through SWIP was LEM 5 that would fly on Apollo 11. So, the Apollo 10 LEM was actually too heavy to lift off from the lunar surface and make it into any sort of orbit where it could rendezvous with a CSM.

Additionally, the computer in LEM 4 was not programmed for the landing. This was mainly because the full landing procedures had not yet been written. Additionally, the Moon's mass-cons, or mass concentrations of material that cause a sort of gravity lump and certain areas, were not fully understood and how they may effect the approach trajectory needed to be studied.

Finally, SNOOPY's ascent stage was shorted on fuel. This was not an effort to prevent those pesky astronauts from pulling a fast one- rather it was done so that the ascent stage would have exactly the same mass as Apollo 11's ascent stage on its trip from 50,000 feet to rendezvous with the CSM. Again, this was to simulate the same conditions as the lunar landing mission. 

Wes' Apollo Part One
volume of the Growing up with Spaceflight series
 has many more interesting details about Apollo 10.

Or for the e-book...

 Growing up with Spaceflight- Apollo Part One

All of that piled onto the fact that humans had only flown to the moon once prior to Apollo 10. This would make a landing attempt on that flight look like pure madness and speculation about such a thing actually sounded like nonsense. Yet still the media speculated on a sneak landing. Cronkite reported that whenever Stafford was asked the question about being tempted to "just ease her down" he, "always had a twinkle in his eye as if he was really planning to do something like that." Of course Tom Stafford has always had a twinkle in his eye normally.

SATURN V S-IC FLOW SEPARATION

The questions always come up on the Internet about the strange back-flow of the Saturn V first stage's exhaust plume. What made it happen? Were the engineers surprised to see it? Was it a concern? Did it happen on every Saturn V or just a few? How high did it go? Was it a danger to the vehicle? And often the answers given on the assorted forums and threads are mostly right or over simplified or even completely wrong.

In fact, the flow separation and resulting back-flow WAS expected. It was seen on the early Saturn I and IB launches. If you get the chance to watch the extended on-board staging films from SA-6 as presented by SpacecraftFilms "The Mighty Saturns- Saturn I and IB" DVD set, you can actually see the sooting of the LH2 vent lines on outside of the S-I inter-stage as the back-flow creeps up. It was no hazard to any of the vehicles and yes, it did happen on EVERY Saturn launch vehicle to one extent or another. The Saturn V was the most visually noticeable.

What made this happen? Well, seen below is the reason as stated by the Saturn V engineers. Now you may see folks argue that their classes in rocket engineering says this or that, but to me, the best answer is here, as stated by the folks who designed, built, flew and studied ALL of the data from the actual vehicle. Thus, it is, in my opinion, the best explanation. Highlighting of items are by me in order to bring to greater light some points of the report. The report itself can be fount on the NASA Technical Reports Server.

"Flow separation (from NASA MSFC MPR-SAT-FE-68-3, June 25, 1968; Apollo 6)

Flow separation was observed on the Saturn I and IB flights and was anticipated on the Saturn V.

Flow separation results from the expansion of the F1 engine plume at the higher altitude. The plumes create what could be considered a solid wall to the oncoming free stream. At lower altitudes, the free stream flow can be deflected around the exhaust plume by the exterral plume shock; but as the plumes increased in size, the free stream flow can no longer turn near the plume service. Consequently, the flow on the side of the vehicle separates or begins to turn before it reaches the plumes. Figure 17 – 18 illustrates the flow field which is obtained after separation occurred. 

Hot gas is fed into the separation region from the base region and plume interface. The base region hot gas results from the engine exhaust flows impinging upon one another and forcing some of the hot gases toward the base heat shield. Separation, once induced, will continue until outboard engine shutdown. As the plume diameter expands with altitude, the point of flow separation moves forward along the vehicle.

Flow separation on the AS-501 and AS-502 flights was first observed between 105 and 110 seconds. Measurements have been made of the point of flow separation for various flight time and are shown in figure 17-18. It is noted in this figure that the separation region extended beyond the top of the S-IC forward skirt just prior to stage separation. The observed blackness on the stage may be a carbon deposit rather than paint being burned."

Note that the "Forward Location" in drawing is incorrect and is corrected in the text. Photos of the Saturn V also shows the back-flow extending beyond the FORWARD S-IC skirt.

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DISCOVERY's Non-Tiles

DISCOVERY's Non-Tiles

NOTE:Some folks post their cool photos and drawings on FaceBook,  but there is a catch. You see when you post a photo on FaceBook you give licence to everyone else on that site to use your photo any way they wish anyplace on that web site. I prefer to control my own photos. So, you are welcome to see my cool photos and stuff here... where I still own them. All photos and images here are copyright Wes Oleszewski and all right are reserved.

Some folks have visited the National Air and Space Museum's Udvar-Hazy facility and seen the Shuttle orbiter DISCOVERY which is interred there. Some folks are planning a visit while others can do little other than dream of a visit to see DISCOVERY. Many walk around her and wonder at the 30,000 plus tiles that served at the vehicle's thermal protection system. When looking, however, take note that not all of those tiles are "the real thing."

When DISCOVERY flew from KSC to Udvar-Hazy, along the way a very few of the actual tiles were lost. The restoration wizards at the NASM decided to replace those missing tiles with some mock-tiles of their own. Looking closely, and spending an hour or so, I managed to pick out some of the mock-tiles which have been labeled with a mock-identification number and the word "FOAM"

Here are my personal pictures of a few such mock-tiles...

Some folks speculate that the moniker "TEM" indicates that the foam tiles were only temporary until NASM's restoration department could get real tiles to replace them.

Find out more about the Shuttles, before they stuffed, mounted and stuck into museums. See what it was like to be there first-hand by reading "Growing up with Spaceflight- Space Shuttle"!

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210 pages!... that's a lot of pages for just $10.95

SATURN V's VANISHING STRIPES

A STORY OF VANISHING STRIPES

Often I see space-buffs on the internet wondering about the paint scheme on the Saturn V's S-IC first stage. The questions surround the roll pattern on the stage's intertank.

Vehicle 500F

When Vehicle 500F, the facilities check-out article was rolled out to Pad 39A on May 24th 1966 the intertank section of the S-IC was adorned with large black stripes and black upper band. This was the original roll pattern planned for all of the vehicles.

An S-IC interstage section

It is important to keep in mind that the sections of the Saturn V were constructed individually and fully painted before being assembled as a complete stage. This was done because each section and component had to be weighed and balanced so that the final exact weight and center of gravity of the entire launch vehicle could be accurately known. The surface area of a complete Saturn V is huge and paint has significant weight. If you don't believe that- go to the hardware store and grab two 1 gallon paint cans in each hand and pick them up.

Lots of cool information such as this can be found in Wes' "Growing up with Spaceflight" six book series. A good place to start if you're an Apollo fan is right here with APOLLO PART ONE. Check it out today!

So it was that vehicles S-IC-D through S-IC-5 (Apollo 10) all came off of the assembly line with the black striped intertank.

After 500F was rolled back to the VAB a strange thing happened to future Saturn V launch vehicles... the intertank black striping vanished! For many years I wondered, like other space-buffs, why it was gone? I found the answer in the April, 1968 issue of "Space World" magazine and an article written by Milton Alberstadt titled "The Saturn 5 gets a New paint job."

500F on LC-39A

When 500F was on the pad doing the facilities check the Florida sun added an unexpected problem to the rush to put men on the moon before the end of the decade. The black surface area was soaking up the sun's heat. Inside the structure the space between the RP-1 tank and the LOX tank got so hot that it was throwing off readings from strain gauges. It was probably also making it hell for the pad rats to work in that area as well. So NASA decided to paint white over the already produced interstages to reflect the Florida sun. Some of the vehicles that had already been delivered to KSC were repainted in the VAB while others were repainted at the Michoud assembly facility.

Apollo 4

Looking closely at the S-IC for Apollos 4 and 6 you can easily see the repainting.

Wanna know more cool stuff like this? Check out my new book series "Growing up with Spaceflight" on Amazon and Kindle!

SKYLAB ONE'S 63 SECOND ANOMALY

HERE'S WHAT ACTUALLY HAPPENED

On May 14, 1973 Skylab 1 was launched and later was found to have been damaged during the ascent. At the time, no one at NASA knew exactly what had happened and information slowly trickled in as data from the workshop's first orbit began to be analyzed, but the full story of what happened would not be made public until August. The result was that NASA fed the media bits and pieces primarily blaming Max-Q. The media fed that to the public and like good parrots the news outlets repeated the story over and over. By the time the full story was published by MSFC three months later, the media had completely lost interest in what really had taken place and the public was left with the earlier reports. Many folks, even today, hold those as fact. Often I see this subject come up on the Internet and many folks, some of whom profess to know what they are talking about, simply have no clue as to what actually happened. I actually saw a post by a person, who I thought to be an actual expert on Saturn vehicles, that stated that the Ares I vehicles "...would suffer from the same sort of vibration that almost destroyed Skylab..." Apparently he had never read the post launch report from NASA's MSFC on the 63 second anomaly, the story of which is far more interesting. Here is the actual story taken from official MSFC reports and not TV "documentaries" produced by people who know nothing about spaceflight, or semi informed internet jabber.
It's way more fun for anyone remembering Skylab 1.

The following is an excerpt from "Skylab- ASTP" volume of "Growing up with Spaceflight" copyright 2014, Wes Oleszewski all rights reserved- no reproduction permitted.

THEY ALMOST LOST THE WHOLE DAMN VEHICLE

Just 49 seconds after liftoff, Skylab 1 was swallowed by a thick layer of clouds that blocked out any view from the ground. That was unfortunate because big problems were just seconds away.

Shortly after vanishing from sight, an “anomaly” occurred aboard the Saturn V that put the entire Skylab program in jeopardy. The events began about 63 seconds after liftoff. This anomaly can be found described in historical shorthand by both NASA publications and media presentations as being the moment when the workshop’s micro-meteoroid shield prematurely deployed, was caught by the slipstream, and torn off the Skylab.

The overall results were workshop overheating and a jammed solar panel wing. The second solar panel wing had been lost off the workshop completely. Although most accounts of the launch and the Skylab program normally leave it at that; a study of the overlooked details of the 63 second anomaly is far more interesting and far more frightening. AS-513, in fact, came within seconds of becoming the first Saturn V to be lost in flight.

At 62.807 seconds after liftoff the launch vehicle began to react to an external, abnormal aerodynamic force. This was 1.707 seconds after Mach 1 (the sound barrier) was passed and was the beginning of the anomaly that was the premature deployment and subsequent loss of the workshop’s micro meteoroid shield.

Most media and poorly researched accounts say that the event took place at “…the point of maximum vibration…” or they will also say it happened at “Max-Q,” or the point where the vehicle experiences maximum aerodynamic pressure. But, Max-Q was a full 10.63 seconds into the future and the meteoroid shield would be long gone by then. What really happened was that as the Mach 1 shock wave passed down the vehicle a reverse flow of air along the skin of the vehicle found its way up what was called the Auxiliary Tunnel (a conduit that ran the length of the workshop). Entering through two uncapped stringers at the base of the tunnel, the high pressure air moved up the tunnel and popped the rubber boot at the top. The airflow then got up under the shield structure and propagated a bulge that was just enough to lift the shield more than 2 inches into the slipstream, which was now at Mach 1.05. By 63.289 seconds into the flight, less than one second after it had started, the damage was done and the shield had torn away and its departure loosened both Solar Array Assembly (“SAS”) wings as it went. The worst of the damage, however, was not done yet.

As the two-and-a-half story tall, 22-foot-long hunk of meteoroid shield fell, it struck the Saturn V at least twice. The first impact was on the S-IVB to S-II adapter, where the debris punched a hole in the adapter’s skin. This showed up in post flight data as the pressure in the adapter area was shown to drop at an abnormal rate. The potentially fatal blow, however, came when the shield’s remains struck the Saturn V for the second time. The impact area included the second plane separation point where the linear shaped charge was located that pyrotechnically blows the parts of the airframe apart so that the “skirt” ring can be dropped after first stage separation. This “skirt sep” often seen in videos, normally took place about 30 seconds after first stage separation. It is a critical event and, in manned Apollo flights, if the skirt failed to separate from the S-II, it was an abort situation requiring use of the escape tower.

The reason why this “skirt sep” is so critical is not one of weight, but rather it is thermal in nature. A back-flow of hot gasses from the five J-2 engines would become trapped in the confines of the skirt and the issue would become critical at center engine cut off. With the four outboard engines still firing in the near vacuum of space, and no center engine to provide its flow, the back-flow of heat would intensify. The temperatures imposed on the base of the stage along the thrust structure would quickly spike and go into the range where a “thermally induced failure” of the stage would take place. In that scenario the thrust structure melts and the burning engines push up into the LOX tank. On AS-513, that is what began to take place and the vehicle was within seconds of failure when S-II’s outboard engines finally shutdown. Had there been the loss of one engine, and the stage had been forced to burn a bit longer to compensate, they would have lost the entire vehicle. Even with the S-II engines burning normally, the estimates are that the Skylab 1 vehicle came within a very few seconds of that disaster.

So, why did the skirt fail to separate and, worse yet, why did the ground controllers not get an indication of failed separation?

Here is why: When the separation signal was sent by the Saturn V’s Instrument Unit (IU), two Exploding Bridge Wire units would fire at opposite ends of the Linear Shaped Charge (LSC) loop that passed completely around the vehicle at the separation plane. The LSC would then blow apart 199 tension straps holding the two sections together, and the skirt would thus be freed to drop away from the S-II stage. A back-up charge would fire if an electrical plug between the two sections did not disconnect, indicating that the two sections were less than ¼ inch apart. On AS-513, the meteoroid shield impacted the seam where the LSC for the skirt was located and it broke the loop. When the LSC fired, the explosion only propagated 165 degrees around the separation plane (about 89 tension straps). But that was enough to pull out the electrical plug used to indicate a separation of more than ¼ inch, so no back-up charge firing was commanded and the signal sent to the ground said that separation had taken place when in fact it had not. Because of the cloud cover, no ground cameras could be used to back up the faulty telemetry, so no one in Mission Control knew that the skirt was still attached. It was calculated that the huge meteoroid shield impacted the S-II skirt at between 200 and 1,000 feet per second. It was a close one; they almost lost the whole damned vehicle.

A second anomaly, which also is often misreported, involved the loss of SAS wing number 2. Most accounts say that it was lost with the meteoroid shield, but in fact it was not! Although loosened by the shield’s departure, SAS wings number 1 and 2 stayed connected to the work shop all the way up. At S-II shutdown, however, four solid fuel retro rockets mounted at 90 degree intervals around S-IVB / S-II forward adapter skirt fired to aid in separation of the S-II from the upper stage. SAS wing number 2 was centered just 16.8 degrees off of one of the retro rockets. The plume from that retro’s firing hit the already loose SAS wing and blew it “…completely off the bird,” as Pete Conrad later observed. SAS wing number 1 was held down by debris from the meteoroid shield which was enough to hold it against its associated retro’s plume.

Although you may see the anomaly sequences misreported in “documentaries” and even in some NASA films, the facts are as stated here. It simply shows that accounts of spaceflight history are normally written by persons too lazy to dig into the post-flight analysis. It also is important to keep in mind that normally NASA films are produced by outside contractors who know little or nothing about the subject, yet were able to make the lowest bid in order to get the project.

Author's Note: Upon reading this, Tom Faber posted the following beyond cool first-hand story, "I knew that the lost solar panel stayed attached until Skylab reached orbit because I saw it that evening (but didn't know what it was at the time). The evening of the launch the local Atlanta TV news reported that Skylab would be visible that evening and gave the time and direction to look. I went out shortly before the appointed time and soon I saw a bright object going NW to SE. Then there were 2 more! Then another 2. Then a 6th object and a 7th! I later found out that in addition to the Skylab itself the others were the 4 sections of the payload shroud, the lost solar panel, and the S-II. It was quite a show!

Find these and more fun details about Skylab and ASTP in my Skylab/ASTP volume of "Growing up with Spaceflight." It is available right now!

Growing up with Spaceflight- Skylab/ASTP

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