Launch News [Sep.1, 2016] Falcon 9 explodes on the Launch Pad

[GLS]

I would not call the RS-25 new. Or the RS-68. Well, maybe the AJ-26.

Isn't that the NK-33 (hw built in the 60s/70s) but with new electronics or control or whatever?

 

[Urwumpe]

Isn't that the NK-33 (hw built in the 60s/70s) but with new electronics or control or whatever?

Exactly. But they did not just replace the electronics, but also changed the starter and pyrotechnics of the engine, or made the engine gimbal much lighter than the original version. Enough changes that would justify calling it a new engine (like in the huge RL-10 family)

---------- Post added at 11:35 PM ---------- Previous post was at 11:29 PM ----------

Generic question, sort of.

I understand the strong-back is there to support the various tanks before they are pressurised?
Any reason they don't use the longtitudinal tension system as in Blue Streak?

http://i89.photobucket.com/albums/k207/Notebook_04/Blue Streak/File0031.jpg

N.

It essentially does the same job - but the Falcon 9 does not use balloon tanks, like old Atlas launchers or the early Centaur stages.

 

[Notebook]

Really, well gob smacked, I assumed it did.

N.

 

[Urwumpe]

Really, well gob smacked, I assumed it did.

N.

From what I can tell by the few references, it does not. It has stringers, which means it does not depend completely on internal pressure. The strongback has more functions anyway, than just keeping the rocket stable.

 

[Notebook]

Well, as you may well know:dry: Blue Streak had stringers on the lower Kerosene tank to support the upper structure when the LOX tank was empty.
But that was a MRBM derived from ATLAS, and things may have moved on a bit..

N.

 

[Urwumpe]

Well, as you may well know:dry: Blue Streak had stringers on the lower Kerosene tank to support the upper structure when the LOX tank was empty.
But that was a MRBM derived from ATLAS, and things may have moved on a bit..

N.

You still have a good reason to keep a stage tensioned during transport: The strongest static loads in the structure come from the engines during flight, so they are designed to withhold these loads - often at the price that other forces can easily damage the rocket. For example, bending loads. That is why you do static testing of a new rocket.

 

[Notebook]

Indeed, dynamic loads in flight, this failed statically, during pressurisation. Its going to be a real doosy to find out what happened.

As a quick aside, Blue Streak didn't have any catastrophic pressurisation problems, it did have a tank reversal during tests, but not in flight testing. Don't know about ATLAS, that was an operational missile and its a bit more quite.

N.

 

[Urwumpe]

Indeed, dynamic loads in flight, this failed statically, during pressurisation. Its going to be a real doosy to find out what happened.

As a quick aside, Blue Streak didn't have any catastrophic pressurisation problems, it did have a tank reversal during tests, but not in flight testing. Don't know about ATLAS, that was an operational missile and its a bit more quite.

N.

I know of at least one tank collapse there, but not in the ICBM:

 

[orb]

I don't link directly the article, but a tweet, because this pic :lol::

[ame="https://twitter.com/NASAWatch/status/782218641508929536"]NASA Watch on Twitter: "Possibility of Sabotage Considered During @SpaceX Investigation https://t.co/OGQblv1QEM @ulalaunch https://t.co/nbNb7h5kQo"[/ame]

 

[Col_Klonk]

..NASA Watch on Twitter: "Possibility of Sabotage Considered During @SpaceX Investigation..

I think it's an engineering fault.. ?

So while Sx and ULA fight it out... BO surges ahead.

 

[N_Molson]

Good thing He is a neutral gas ! :lol:

 

[Col_Klonk]

Inert Gas ?

 

[N_Molson]

Yeah, inert... In French we say "gaz neutre" so it was a word-to-word translation

 

[RisingFury]

Yeah, inert... In French we say "gaz neutre" so it was a word-to-word translation

Don't worry, we all got the joke. Except for one person

 

[IronRain]

Spaceflight101.com: SpaceX resorts to ‘Creative’ Testing in Falcon 9 Explosion Investigation

SpaceX President Gwynne Shotwell spoke twice last week, at the APSSC Satellite Conference in Malaysia and the annual meeting of the National Academy of Engineering in Washington, reaffirming that the culprit lies within “business processes” and continuing to express hope that Falcon 9 can resume flying before the end of the year.

SpaceX confirmed on September 23 that the explosion was due to “a large breach in the cryogenic helium system of the second stage liquid oxygen tank.” Being more specific, Shotwell said the prime candidate for the failure was a helium pressure ‘letting go’ – industry speak for rupturing.

The COPVs, Composite-Overwrapped Pressure Vessels, are responsible for storing high-pressure helium which is heated up in flight and supplied to the fuel and oxidizer tanks to keep them at the proper pressure levels to ensure the vehicle’s stability and propulsion system operation. Falcon’s COPVs measure around 60 centimeters in diameter, stand 1.5 meters tall and a pressurized to over 350 bar.

On Falcon 9, COPVs on the first and second stage are installed within the Liquid Oxygen tanks and immersed in the sub-cooled oxidizer.

 

[Longjap]

Spaceflight101.com: SpaceX resorts to ‘Creative’ Testing in Falcon 9 Explosion Investigation

If that's the case that's the second time. Didn't they move the COPV's inside the tanks after the loss of CRS-7?

 

[Urwumpe]

If that's the case that's the second time. Didn't they move the COPV's inside the tanks after the loss of CRS-7?

AFAIR they have always been there. Its essentially the only place where you can put them. The alternative would be outside the rocket, unless you have a huge interstage or other structure to store them.

On the Ariane 5, the Helium cryostat is for example mounted outside the tanks, on the EPC thrust structure.

 

[DaveS]

AFAIR they have always been there. Its essentially the only place where you can put them. The alternative would be outside the rocket, unless you have a huge interstage or other structure to store them.

On the Ariane 5, the Helium cryostat is for example mounted outside the tanks, on the EPC thrust structure.

Same for Centaur, COPVs mounted on the aft LOX tank bulkhead.

 

[Urwumpe]

Same for Centaur, COPVs mounted on the aft LOX tank bulkhead.

I think for the only other times, the helium was stored inside the tanks, they used solid aluminum tanks, not COPVs.

COPV was used for storing super cold liquid helium, but it was never yet used submerged in super cold liquid oxygen.

---------- Post added at 05:51 PM ---------- Previous post was at 05:44 PM ----------

Atlas V and Delta IV also store the Helium outside the tank. The Delta IV CBC only needs Helium for engine start and engine control, the tanks are pressurized with gaseous propellant.

 

[Longjap]

T-0:09:15 - Stage 1 Helium Topping

T-0:07:45 - MVac Fuel Trim Valve Setup

---------- Post added at 04:16 PM ---------- Previous post was at 04:15 PM ----------

Could be the stage 1 helium topping?
Why don't they pressurize the LOX tank with its own gas?