Anyone familiar with this 'claim' at Aulis.com?

[Eventcone]

That's excellent - just what I was hoping someone would turn up - an alternative film that is continuous (unedited) from launch to cloud penetration. AND it shows that the cloud penetration occurred much earlier and much lower (as I suspected). Many thanks.

The authors of the Aulis article claim that Pollacia's film shows the true sequence of events in proper time, but all they do to establish this is confirming with Pollacia that the film has not been manipulated, and perform some simple analysis to try to support the films correct timing (using what they mistakenly believe is the S-IC separation as a time stamp.)

Just curious - why do you conclude that they are mistaken about the S-IC separation?

Finally, in the HD clip that you posted, is that a conical shock wave that we see ripple through the cloud layer? If so, might that offer another method by which the stack velocity could be determined (demonstrated) at that time-point?

[Jason Thompson]

Just curious - why do you conclude that they are mistaken about the S-IC separation?

For one thing the video doesn't go as far as S-IC separation. What they have identified as S-IC separation is not. Their 'cloud of hot gas' surrounding the rocket is actually a contrail.

If you watch liftoff footage of many rockets you will notice there is a period during which the rocket is ascending through a region where atmospheric conditions allow the formation of a large white contrail behind it. This contrail then stops when the rocket passes into a region where water vapour from the exhaust no longer condenses to make a white cloud. First stage separation of the Satrun V occurs well above this altitude, and once you have seen a decent quality piece of footage you'll immediately realise you can't mistake this for a staging event. The staging event is much less protracted and very distinctive.

[smartcooky]

A couple of questions just to satisfy my own curiosity....



What are the trails of white smoke/mist/vapour that are emanating from the junction of the first and second stages?

Why would they be twisting around the stage instead of just going straight down?

- Surely the stack is not travelling fast enough yet to generate significant vortices?
- Its not caused by the stack rolling because it hasn't cleared the tower yet, so the roll programme hasn't started.

[cjameshuff]

What are the trails of white smoke/mist/vapour that are emanating from the junction of the first and second stages?

The usual fog you get around cold objects or from sources of cold gas, like tanks and plumbing full of liquid oxygen.

Why would they be twisting around the stage instead of just going straight down?

It might not be twisting: on the right, the streamers seem pretty vertical, on the left they seem to be pulling away from the rocket. Several things could be the cause: a breeze, differences in the air currents due to the presence of the tower, momentary slight sideways motion of the rocket itself...

[ka9q]

And there is indeed a momentary sideways motion of the rocket. At T+1.7 sec (1.4 sec after first motion) the Apollo 11 Saturn V executed a 1.25 deg yaw maneuver away from the tower to give it a little extra margin against wind pushing it into the tower. This maneuver ended at T+9.7 sec, about the time of tower clear. At T+13.2 sec it began the roll and pitch maneuver.

BTW, the white stuff is actually coming from the outside of the LOX tank in the upper half of the first stage (the RP-1 fuel tank at the base of the rocket is at ambient temperature.) The entire tank is covered with ice, which is why it's white. Much of it fell off at liftoff, which it's starting to do here.

[Noldi400]

And there is indeed a momentary sideways motion of the rocket. At T+1.7 sec (1.4 sec after first motion) the Apollo 11 Saturn V executed a 1.25 deg yaw maneuver away from the tower to give it a little extra margin against wind pushing it into the tower. This maneuver ended at T+9.7 sec, about the time of tower clear. At T+13.2 sec it began the roll and pitch maneuver.

BTW, the white stuff is actually coming from the outside of the LOX tank in the upper half of the first stage (the RP-1 fuel tank at the base of the rocket is at ambient temperature.) The entire tank is covered with ice, which is why it's white. Much of it fell off at liftoff, which it's starting to do here.

Michael Collins describes those first few seconds, as only he can:

"It is steering like crazy, like a nervous lady driving a wide car down a narrow alley, and I just hope it knows where it's going, because for the first ten seconds we are perilously close to that umbilical tower."

[ejstans]

Just curious - why do you conclude that they are mistaken about the S-IC separation?

For one thing the video doesn't go as far as S-IC separation. What they have identified as S-IC separation is not. Their 'cloud of hot gas' surrounding the rocket is actually a contrail.

If you watch liftoff footage of many rockets you will notice there is a period during which the rocket is ascending through a region where atmospheric conditions allow the formation of a large white contrail behind it. This contrail then stops when the rocket passes into a region where water vapour from the exhaust no longer condenses to make a white cloud. First stage separation of the Satrun V occurs well above this altitude, and once you have seen a decent quality piece of footage you'll immediately realise you can't mistake this for a staging event. The staging event is much less protracted and very distinctive.

Exactly. Here's footage from Apollo 16 showing the contrail (right after the 2-minute mark):

[Jason Thompson]

A couple of questions just to satisfy my own curiosity....



What are the trails of white smoke/mist/vapour that are emanating from the junction of the first and second stages?

It's ice that has formed on the outside of the first stage LOX tank. The upper boudary of that ice 'cloud' is actually the lower edge of the forward skirt of the S-IC stage. A little above that you can see a white line. This is the forward end of the S-IC stage. The white line is the linear shaped explosive charge that is used to separate the stages. Above that is another white line/shaped charge, which is the forward edge of the interstage section.

As to why it's not going straight down, I'm not sure, but I'd guess, as others have said, it has something to do with the yaw in the early part of the flight.

[ka9q]

Michael Collins describes those first few seconds, as only he can:

"It is steering like crazy, like a nervous lady driving a wide car down a narrow alley, and I just hope it knows where it's going, because for the first ten seconds we are perilously close to that umbilical tower."

Another frequent astronaut simile is a runaway freight train going down an old, poorly maintained track. The Saturn V Flight Reports have detailed plots of steering positions, rates and errors for each stage, and they show the engines took a couple of seconds to actually swing the launcher around in response to a step change in commanded attitude. For A11, peak yaw rate was +0.5 deg/s at T+5 s during the yaw maneuver and -0.5 deg/s at T+12s after it ended. It probably felt much greater in the CM because the center of gravity at liftoff was so low.

Still, the report says the first stage engines used only 10% of their "gimbaling authority" (steering range). Imagine what it would have felt like if they had swung rapidly from one stop to the other.

The report also says the winds at launch were 3.3 m/s from the south at the 18.3 m level. (The tower was on the north side of the vehicle.)

[gwiz]

But it is possible to find other independent sources, such as this, also shot with an 8mm film camera:

Welcome to the forum, that's a first post that makes a really valuable contribution to the thread.

[Bob B.]

Thanks, ejstans.  Welcome to the forum.

Based on the new videos, it looks the Saturn V passes through the clouds at about T+54 seconds, or half the time claimed by Aulis.  If we assume their video is running at half-speed, then their calculation is off by 2X (that's assuming we trust their method).  That makes their speed about 200 m/s rather than 100 m/s.  The earth-fixed velocity at T+54 s as recorded by NASA was 221.5 m/s.

[gwiz]

Incidentally, look at the shadow on the HD video posted by ejstans.  You can clearly see the actual rocket, partly inside a condensation cloud mainly concentrated round the second stage, and with a trailing exhaust.  No doubt that the exhaust casts a shadow.

[JayUtah]

Imagine what it would have felt like if they had swung rapidly from one stop to the other.

That's compelling to think about, but my gut says that would stand a good chance of demating the stages.

The report also says the winds at launch were 3.3 m/s from the south at the 18.3 m level. (The tower was on the north side of the vehicle.)

Best explanation I can see for the direction of the vapor trails.

[gillianren]

Another frequent astronaut simile is a runaway freight train going down an old, poorly maintained track.

That's a simile I like better.  No need to bring the "woman driver" stereotype into things!

[Jason Thompson]

The report also says the winds at launch were 3.3 m/s from the south at the 18.3 m level. (The tower was on the north side of the vehicle.)

Best explanation I can see for the direction of the vapor trails.

D'oh! Why didn't wind occur to me?