Couple Saturn V questions

[mako88sb]

A couple topics that I didn't know anything about until recently. 

First off is the tapered pins and dies used to help "soft release" the Saturn V during its launch as mentioned in this thread:
http://www.collectspace.com/ubb/Forum29/HTML/001327.html

Just curious if there is better info about this around? Also, did they have something similar for the shuttle launches and what are they planning for the SLS?


Next is the LES regarding the ballast below the nose cone that had depleted uranium and lead in it to help with aerodynamic stability.
http://nassp.sourceforge.net/w/images/thumb/5/52/LET.png/502px-LET.png

I can't seem to find anything more about this. Be interesting to find out how it was determined that they needed it and how they engineered the solution.

[Geordie]

A couple topics that I didn't know anything about until recently. 

First off is the tapered pins and dies used to help "soft release" the Saturn V during its launch as mentioned in this thread:
http://www.collectspace.com/ubb/Forum29/HTML/001327.html

Just curious if there is better info about this around? Also, did they have something similar for the shuttle launches and what are they planning for the SLS?

There's a reference to them in David Woods' How Apollo flew to the Moon (p. 67. Web edition here):

  The release of the Saturn V was not instantaneous: it was once described as more of an ooze-off than lift-off. This was in part due to a number of tapered pins mounted to the launch platform, which were pulled through dies affixed to the bottom of the S-IC. Their deformation controlled the acceleration of the rocket for the first 15 centimeters of ascent.

EDIT: Of course, he doesn't say why. I might try emailing him and asking directly.

EDIT: http://forum.nasaspaceflight.com/index.php?topic=1322.100 touches upon it, and has in interesting diagram:


EDIT: Okay here we go, from the Saturn V Flight Manual (by way of the aforementioned forum): "Controlled release mechanisms are used to provide a gradual release of the stage at launch, thereby keeping the dynamic loads at launch within the design capability of the vehicle."

[mako88sb]

Thanks, Geordie: I should have mentioned I do have some books that have similar info but unfortunately don't go into much detail about them. They initially started off with 16 and as the link mentions, gradually reduced them until they only used 8. Just wanted to get some info about how they decided to go this route and better pictures. The link also mentions a video series titled "Mighty Saturns: Saturn V" that has more video clips of them. I tried getting this but it's outrageously expensive, for us Canadians at any rate.

[Geordie]

The link also mentions a video series titled "Mighty Saturns: Saturn V" that has more video clips of them. I tried getting this but it's outrageously expensive, for us Canadians at any rate.

You're not kidding--I had to sit down when I saw the price. Amazon Canada has a used one, for about half price.

I don't know the answers to most questions asked on this site, but I like web-researching them, as I learn a lot by doing so.

[Geordie]

I don't know the answers to most questions asked on this site, but I like web-researching them, as I learn a lot by doing so.

Such as this:

Little known is that after the Hold Down Arms retracted during a Saturn V liftoff, the rocket had one more process to go through before it was free of the Earth.

Dies mounted to the Saturn V near the Hold Down Arm attachment were connected to tapered pins mounted on a bracket on the Hold Down Arm structure. The purpose was to gradually (less than 1 second) release the Saturn V to prevent an abrupt or a "spurt" in the liftoff which could shake/damage the entire rocket beyond design limits.

The pins were pulled through the dies for the first six inches of travel and then released as the Saturn V continued upwards. Initially 16 pins were used, but by the end of Apollo only 8 pins were used. The pins were essentially soft iron bolts that squeezed through the dies like taffy as the rocket travelled upward.

Photo #1 shows the mounting bracket on the Hold Down Arm and die & pin, partially obscured by the Tail Service Mast, at ignition. #2 shows the pin being pulled through the die as the rocket begins to climb and #3 shows the dies on the bottom of the Saturn V.

From https://www.facebook.com/FlightOfApollo/videos/1118603064916338/

The images referred to are also on the Facebook page.

[Zakalwe]

The link also mentions a video series titled "Mighty Saturns: Saturn V" that has more video clips of them. I tried getting this but it's outrageously expensive, for us Canadians at any rate.

You're not kidding--I had to sit down when I saw the price. Amazon Canada has a used one, for about half price.

I don't know the answers to most questions asked on this site, but I like web-researching them, as I learn a lot by doing so.

Theres a new DVD on Amazon UK for £65 GBP.

If you can't get them to ship it, then I could get it and send post it (you cover purchase and costs, obviously ) 
£65 is about 123 of your Canuck bucks.

[Jason Thompson]

You can always go direct to source:

http://spacehistory.tv/blog/?post_type=product&paged=4

The DVD series is excellent but if you want information about some of the specifics you'll be disappointed. It has a one hour documentary about the Saturn V which is fascinating but naturally short on detail as it's a complex beast to cram into one hour. There's a LOT of film footage of the various launches. For my money the bit that's worth the purchase cost alone is the third disc with a load of quarterly film reports from NASA about the development of the Saturn V.

Theset about the Saturn I is also interesting, though less so than the Saturn V set.

The primary goal of Spacecraft Films is to get much of the film and TV footage out, not to be an extensive resource for engineering details. I've collected most of their output over the years.

[mako88sb]

Well, today I stumbled upon a pdf that goes into a bit more detail about the first topic I asked about. Quite a bit of info I hadn't seen before regarding the hold-down arms and release system and the differences from what was used on the Saturn 1 & 1B vs the Saturn V. THey even mention how they used oak blocks of wood for shock absorbers.
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760012107.pdf