SpaceX Dragon 2 Updates and Discussion - Thread 3

[Stimbergi]

https://twitter.com/lavie154/status/1528773848635539463

Hang on. This is a thing I’ve been aware of for quite a while. Know some people that are very well in the know and this is not the story I’ve heard.
...
I can’t go into many details, but the part about hypergolics is, as far as I’m aware, flat out untrue. Crew-4’s heat shield is not compromised. And the NESC signed off on all of this.
...
How does hypergol intrusion into the heat shield even make any sense? How does it get there? The entire propulsion systems are walled off.

Either way, you’re telling me the prop system has been quietly leaking hypergolics inside the capsule? That should be a much bigger issue

[eeergo]

In a discussion like this, I like to know what is the source, who is speaking. This Space Explored web site and Derek Wise are completely new to me.

Are they recent ? what is their background, their business model, their target audience ? can it be a case of a new web site seeking to establish notability ?

As long as the sources are who they claim to be in the article and the information accurate, I wouldn't care one iota at what their target audicience or business models are. The website shows article from as far back as 2 years ago from a quick glance.

[hektor]

There is a wide range of business models, and it can go from The Washington Post to the Weekly World News.

[eeergo]

There is a wide range of business models, and it can go from The Washington Post to the Weekly World News.

I agree and I understand your argument - still, my point regards the information nuggets alone, devoid of subjective commentary on top: it could be the Onion or InfoWars as far as I'm concerned, as long as its sources are reliable and the information veridic.

[Robotbeat]

It does seem to be sensationalized, and they also seem to not really understand the technicals very well, so it’s questionable the issue is actually factually how they present it.

NESC would study the issue even if it was just an accelerated ablation rate. Or just a hypergol leak alone. Stuff like this happens, and it’s carefully investigated as it should be. It’s unfortunately common to have near misses that are investigated, as spaceflight is still early.

So it’s not possible to tell the severity of the issue by the sensationalization of this one outlet.

[whitelancer64]

https://spaceexplored.com/2022/05/23/spacex-heat-shield-issues/

I've just seen this posted on Facebook. Some relevant quotes from that article:

SpaceX Dragon hypergolic leak risked crew, NASA investigation underway

*snip*

If this article is accurate (a big "if"), would not ASAP have had something to say about it?

I wouldn't doubt that they're looking at the issue, but NASA ASAP issues periodic statements and reports, they wouldn't immediately blast their first hot take out on Twitter the second it crossed their desks.

[eeergo]

See: https://forum.nasaspaceflight.com/index.php?topic=50309.msg2371562#msg2371562

i.e. most likely fully debunked.

[gemmy0I]

See: https://forum.nasaspaceflight.com/index.php?topic=50309.msg2371562#msg2371562

i.e. most likely fully debunked.

Cross-post of the official NASA statement from the Axiom-1 thread:

Here's the full official statement from NASA that Davenport is quoting from, as recently retweeted on the main @NASASpaceflight (Chris B) account:

https://twitter.com/lorengrush/status/1529144891472748544

Some interesting information in here, including the fact that SpaceX has in fact reused some PICA-X tiles on previous *cargo* Dragon flights (which may have been stated publicly before, but was new to me at least).

[Jim]

Its interesting seeing Boeing using a plug style door. I'm assuming they have a clever way of preventing the 100lb hatch from smacking someone in the face if they needed to use the top hatch. This is verses the Dragons hinge mechanism which restrains the hatch (presumably for earthbound ease of access to the top hatch).

This got me thinking about the logistics for Dragon rescue. Are the pyros strong enough to push the nose cone off so that they can utilize the top hatch? Is the nose cone actuator strong enough to actuate in earth gravity?

Apollo used the same method as Boeing and it was an alternate escape route.

[king1999]

Dragon has a obstructed forward hatch. How does it ditch the nose cone / provide access to the front hatch? Starliner is also in a similar boat with their NDS hatch cover.

Why do they need to ditch the nose cover? It has a hinge and may act like a car trunk cover which you can open from inside or outside.

[cohberg]

Side hatch close out panel has changed to a "quick release" design between crew-2 and crew-3

We now have detailed instructions for the toilet, clearly demonstrating a separate urinal funnel and waste bags for solids

All
1. Install camera caps
2. Retrieve Daily Bag from Location 18, stage near toilet
3. Ensure Location 21 is closed
4. Retrieve privacy curtain from Location 8, install
Solid Waste
5. Unpin, deploy toilet
6. Remove toilet lid, temp stow in privacy curtain
7. Install fecal bag in toilet
8. Turn on waste fan, confirm airflow
Urine
9. Turn on waste fan
10. Destow funnel, confirm airflow

[cohberg]

Dragon Abort QRH from Crew 4 ascent photos.

Of note:

All aborts from Stage 1 (1A + 1B) are with the trunk for aerodynamic reasons.

Most aborts from Stage 2 (2A - 2D) are performed without the trunk. This makes sense as you are already high enough in the atmosphere and you want the additional performance

Additionally, powered aborts (2A - 2D) fire in various orientations (ranging from heavily prograde to partially retrograde) depending on phase of flight.

I annotated the downrange abort exclusion zone figure Jorge linked, to illustrate Dragon orienting to make the St Johns or Shannon landing areas.

[Jorge]

Dragon Abort QRH

Most 2 'X' (2nd stage aborts) are performed without the trunk (vs stage 1 modes 1A + 1B with trunk for aerodynamic reasons). This makes sense as you are already high enough in the atmosphere and you want the additional performance

Additionally, it appears that not all the abort thrust directions are entirely prograde? Some 2X aborts appear to be firing partially retrograde. Is this for g loading /  to make a recovery zones?

The latter. See:
https://ntrs.nasa.gov/api/citations/20170001943/downloads/20170001943.pdf

Page 47, "3.3.1.7 Aborts outside DAEZ". There's a figure on page 183. Basically if the instantaneous impact point (IIP) of the spacecraft is already past St. John's, the abort would be retrograde to get back to it.

[jketch]

NASA has reportedly purchased an additional 5 Crew Dragon flights, bringing the total to 14.

https://arstechnica.com/science/2022/06/nasa-just-bought-all-the-seats-needed-for-space-station-crews-into-2030/

[hektor]

https://twitter.com/joroulette/status/1536341276085342209?s=20