Safety Panel Raises Concerns about SpaceX Falcon 9 Pressure Vessel for Commercial Crew Missions

space.com ^ | 01/15/2018 | Jeff Foust

[BenLurkin]

An independent safety panel recommended NASA not certify SpaceX's commercial crew system until the agency better understands the behavior of pressure vessels linked to a Falcon 9 failure in 2016.

That recommendation was one of the stronger items in the annual report of the Aerospace Safety Advisory Panel (ASAP) released by NASA Jan. 11, which found that NASA was generally managing risk well on its various programs.

The report devoted a section to the composite overwrapped pressure vessels (COPVs) used to store helium in the second stage propellant tanks of the Falcon 9. The investigation into the September 2016 pad explosion that destroyed a Falcon 9  while being prepared for a static-fire test concluded that liquid oxygen in the tank got trapped between the COPV overwrap and liner and then ignited through friction or other mechanisms.

SpaceX has since changed its loading processes  to avoid exposing the COPVs to similar conditions, but also agreed with NASA to redesign the COPV to reduce the risk for crewed launches. NASA has since started a "rigorous test program" to understand how the redesigned COPV behaves when exposed to liquid oxygen, the report stated.

[Vaquero]

Helium is not a propellant or an oxidizer.

[blueunicorn6]

What commercials are they gonna make in space?

“Have you or a loved one ever been injured or killed by spackle? If so, call our law offices here in space.”

[BwanaNdege]

Helium is not a propellant or an oxidizer.

Exactly! As I understad it, the helium pressure pushes the fuel & oxidizer from their tanks to the engines, eliminating the need for heavy, expensive and prone to mechanical failure turbo pumps.

Can anyone explain this convoluted paragraph?

"The report devoted a section to the composite overwrapped pressure vessels (COPVs) used to store helium in the second stage propellant tanks of the Falcon 9. The investigation into the September 2016 pad explosion that destroyed a Falcon 9 while being prepared for a static-fire test concluded that liquid oxygen in the tank got trapped between the COPV overwrap and liner and then ignited through friction or other mechanisms. "

Huh??

OK. this explains it. The COPV tank stores BOTH Helium and Oxygen.

[Vaquero]

The helium pressurization reminds me of how ICBMs are blown out of subs.

They have a small tank filled with water. They fire a small solid rocket motor thrust end into the water which flashes the water into steam. The steam pressurizes the tube blowing the icbm out with great force so it pops out of the sea. Then it’s own rocket engine ignites.

[SunkenCiv]

Thanks BenLurkin. The reek of Richard Shelby is all over this.

[BwanaNdege]

The neat thing about the SSBN launch system, in addition to the simplicity, is that (I’m told) the missile travels up to the surface through the water inside the steam bubble, so it experiences NONE of the hydrostatic pressure!

I’ve got a space rocket launcher design that works on a giant version of that, similar to Tesla’s HyperLoop.