SpaceX COTS Demo 1 Updates

[Dave G]

Did the first F9 have that clean flat expanse of white insulation(?) on aft surface of the thrust structure, with openings only for the throats of the engines and the turbopump exhausts? 

It could be something they just use for shippnig and storage, and then remove before launch.  Sort of like the white plastic you see on new cars in transit to dealers.

[iamlucky13]

It looks more substantial and neatly integrated than a shipping or storage cover. Look at the rows of what appears to be fasteners.

Also, looking back through the updates, I think the flight 1 Falcon 9 did have these covers. The only view of that angle I've come across searching their site are videos of the rollout and the pad static fire. It's not very high resolution or from great angles, but the area between the engines appears to be filled in.

http://www.spacex.com/multimedia/videos.php?id=48
http://www.spacex.com/multimedia/videos.php?id=45

In contrast, when they first rolled a vehicle to the pad in spring 2009, it definitely did not have covers between the nozzles and the engines, nor any of the fairings around the engines.

Current:
http://www.spacex.com/assets/img/20101001_integrated.jpg

May 2009:
http://www.spacex.com/assets/img/20090108_elonf9.jpg

[zaitcev]

I would really love to know how they manage to make the supports for the capsule to penetrate the heat shield without causing a burn-through.

[beancounter]

I would really love to know how they manage to make the supports for the capsule to penetrate the heat shield without causing a burn-through.

I'll second that.  Must have a solution but it escapes me!!

[Jorge]

I would really love to know how they manage to make the supports for the capsule to penetrate the heat shield without causing a burn-through.

I'll second that.  Must have a solution but it escapes me!!

Probably similar to how the orbiter's forward ET attach point ("arrowhead") works, though I can't find a good online reference at this point.

[subzero788]

How were the Apollo Command/Service modules attached?

[Jorge]

How were the Apollo Command/Service modules attached?

Tension ties around the edges of the TPS.

[mr. mark]

At :26 seconds in on the new Falcon flight 1 video, you can just make out the covers for the first stage engines. They seem to be a slightly different color but the housing around them is still white.

[Lars_J]

I would really love to know how they manage to make the supports for the capsule to penetrate the heat shield without causing a burn-through.

This is interesting... I decided to Google an image of the Orion heat-shield for comparison - and what do you know, this prototype *also* has 'holes' like that: http://xpda.com/junkmail/junk198/heatshield.jpg
This rough Orion capsule schematic side view also shows holes/something there: http://a52.g.akamaitech.net/f/52/827/1d/www.space.com/images/060926_cev_schem_02.jpg

And what about Apollo? Check out the Apollo 11 heat shield on display: http://lh4.ggpht.com/_7gD73enqswE/SUASyr2NyfI/AAAAAAAAEJs/qmslUAu5q0M/s912/IMG_6368.JPG - It also has similar holes.
This Apollo 17 pre-launch picture shows holes (some freshly painted over): http://www.hq.nasa.gov/office/pao/History/alsj/a17/ap17-KSC-72C-1084.jpg

So this method of some (apparent) structural support of the capsule through the heat-shield seems to be a common thread for U.S capsules since Apollo. Perhaps someone with more background can explain how burn-through is prevented.

[Lars_J]

An addendum to my last post - This CAD model of the Orion SM appears to show the 6 structural support pads that line up with the 6 holes in the heat shield: (they have a green color)
http://img136.imageshack.us/img136/4953/orioncargospacefc8.jpg

[Lars_J]

AHA! Success - This NASA PDF file explains these "compression pads" (what the holes are):

"Analysis of Compression Pad Cavities for the Orion Heatshield"
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090007607_2009006273.pdf

Preliminary design of the Orion module and heatshield has leveraged technology and design solutions from Apollo wherever possible. One example is the support of mechanical loads between the command module (Orion) and service module when stacked for launch. In this configuration, launch loads must transfer through connections on the bottom of the capsule which penetrate though the windward reentry heatshield. Lightweight thermal protection materials for the heatshield do not possess the mechanical strength for support so, like Apollo, the Orion loads are transferred through densified compression pads embedded within the windward heatshield. A seamless integration of the compression pads within the heatshield would be ideal; however, the need for mechanical connections and even different rates of material ablation dictate some form of surface discontinuity.

EDIT: another PDF here: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080008297_2008007430.pdf

[beancounter]

Ok that explains a lot.  But I don't think SpaceX will use tension ties through the heatshield.  A simpler method would be external latches of some sort which I would think would maintain the integrity of the heat shield but that's only my uniformed opinion FWIW. 

[Lars_J]

Ok that explains a lot.  But I don't think SpaceX will use tension ties through the heatshield.  A simpler method would be external latches of some sort which I would think would maintain the integrity of the heat shield but that's only my uniformed opinion FWIW. 

No, as you can see in this image ( http://images.spaceref.com/news/2010/20101001_rotating.jpg ) the edge of the heat shield extends beyond the trunk. The only way to attach it firmly to the trunk is through some kind of tension tie mechanism through those 5 or 6 compression pads.

[beancounter]

Ok that explains a lot.  But I don't think SpaceX will use tension ties through the heatshield.  A simpler method would be external latches of some sort which I would think would maintain the integrity of the heat shield but that's only my uniformed opinion FWIW. 

No, as you can see in this image ( http://images.spaceref.com/news/2010/20101001_rotating.jpg ) the edge of the heat shield extends beyond the trunk. The only way to attach it firmly to the trunk is through some kind of tension tie mechanism through those 5 or 6 compression pads.

Ok guess that would prevent any possible edge damage to the heatshield as well.  Still don't like the idea of putting something through the heatshield but guess they've got it covered.

[JayP]

Ok that explains a lot.  But I don't think SpaceX will use tension ties through the heatshield.  A simpler method would be external latches of some sort which I would think would maintain the integrity of the heat shield but that's only my uniformed opinion FWIW. 

No, as you can see in this image ( http://images.spaceref.com/news/2010/20101001_rotating.jpg ) the edge of the heat shield extends beyond the trunk. The only way to attach it firmly to the trunk is through some kind of tension tie mechanism through those 5 or 6 compression pads.

Ok guess that would prevent any possible edge damage to the heatshield as well.  Still don't like the idea of putting something through the heatshield but guess they've got it covered.

You’ve got to remember, heat shields aren’t magic. You can have a metallic protrusion thru the heat shield with no problem. All you need is a large enough mass of metal with reference to the area (of metal) that is being heated that can absorb the heat that is being applied. It’s called a heat sink. That is how the bi-pod mount on the shuttle works. In the center of the RCC arrow head is the circular metallic section (that is really 3 coplanar faces –the outer housing, the face of the spherical bearing and the sheared off end of the actual connecting bolt). It’s mounted in a heavy housing at a point where a lot of the structure comes together. All that structure absorbs the heat that is applied to the external faces. You could, in-fact, cover the entire bottom of the capsule in a 3 in thick layer of beryllium and it would survive the reentry just fine, it just would be to heavy to launch.

[jabe]

I would really love to know how they manage to make the supports for the capsule to penetrate the heat shield without causing a burn-through.

I asked that back here
http://forum.nasaspaceflight.com/index.php?topic=22769.msg644750#msg644750
Ben the space brit ansswered..

They aren't holes, they are geometric shapes in the PICA material into which the trunk attachment pads will fit.  the raised sides will stop the Dragon rotating atop the trunk during high-vibration flight modes.

jb

[beancounter]

My understanding is that they will use tension ties through the heatshield at the pad locations.  It seems the shape of the 'holes' (and particularly their edges - bevel angle) which take the pads prevent major blow through of heat gases.  The gas boundary layer apparently only flows down into the hole a certain distance but not sufficiently to blow through. 
There's a paper on another thread describing the testing and analyses that was done for Orion which is proposed to use a similar system.  They also compared PICA and AVCOAT.  Seems AVCOAT was superior. Wouldn't you know it, can't find the link now!!  Hope I've got that right!!

[go4mars]

  They also compared PICA and AVCOAT.  Seems AVCOAT was superior. Wouldn't you know it, can't find the link now!!  Hope I've got that right!!

Here's the link:

http://techfragments.com/news/688/Science/NASA_Selects_Avcoat_As_Heat_Shield_Material_for_Orion.html

Although PicaX, is apparently superior to the PICA used on the stardust mission, so it isn't clear which is better between PicaX and Avcoat. 

[beancounter]

  They also compared PICA and AVCOAT.  Seems AVCOAT was superior. Wouldn't you know it, can't find the link now!!  Hope I've got that right!!

Here's the link:

http://techfragments.com/news/688/Science/NASA_Selects_Avcoat_As_Heat_Shield_Material_for_Orion.html

Although PicaX, is apparently superior to the PICA used on the stardust mission, so it isn't clear which is better between PicaX and Avcoat. 

Ah thanks.

[Ben the Space Brit]

The Delta-IVH launch with the NROL-32 recon-sat keeps on slipping; I note that it seems to have reached 11/5 now.  What is the latest it can happen before SpaceX have to give up their 11/8 launch slot?