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#1 2019-10-10 14:59:44

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,868

Rocket Lab's Electron Rocket

Interesting that Rocket Lab's Electron Rocket has an engine which is completely 3D printed.

Perhaps the Mars settlement could begin manufacturing its own rockets at an earlier stage than I first thought.

Maybe a Mars ISRU Rocket could be used to assemble an Interplanetary Transport Vehicle and Electron-style rockets could be used to power it to LEO...

https://www.youtube.com/watch?v=U5k1mlu6A7I


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#2 2020-01-20 17:02:01

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

I think that there is another topic for this company but here is news for them
https://spacenews.com/rocket-lab-to-lau … ce-office/

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#3 2020-02-15 21:03:30

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

A 2018 series of new CubeSats now are in space, conducting a variety of scientific investigations and technology demonstrations, following launch Sunday of Rocket Lab’s first mission for NASA under a Venture Class Launch Services (VCLS) contract.

Guess who is launching a mission for Nasa... Rocket Lab wins contract to launch NASA lunar cubesat mission

https://www.rocketlabusa.com/news/updat … -the-moon/

Rocket Lab’s Electron rocket stands around 55 feet (17 meters) tall, shorter than even the Minotaur booster that sent NASA’s LADEE probe to the moon in 2013. An Electron rocket will launch NASA's CAPSTONE lunar cubesat mission in early 2021 from Wallops ...

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#4 2020-07-31 19:39:01

tahanson43206
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Registered: 2018-04-27
Posts: 3,511

Re: Rocket Lab's Electron Rocket

This post is about the failure analysis of the recent Rocket Lab launch attempt.

https://www.yahoo.com/news/very-very-sn … 50936.html

The vehicle failed 'gracefully' so that the data collected on board during the flight could be transmitted to the ground stations.

After months of analysis, the fault team determined that an electrical connector overheated during flight.

The part had been rigorously tested on the ground, as had all components of the vehicle.

The conditions of flight were not present during the ground testing.

As I understand the statement, future testing will be extended so as to reveal weakness of each connector in the battery pack involved.

(th)

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#5 2020-07-31 19:45:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

So a connection was forced to supply more power than designed.
Seems that an electric stress was not verified or tested for.
Dc and AC power behaves differently for connections as its surface area, thickness and contact resistance as to when more power is passed through the connection.

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#6 2020-07-31 20:23:56

tahanson43206
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Registered: 2018-04-27
Posts: 3,511

Re: Rocket Lab's Electron Rocket

For SpaceNut re #5

Your reading of the report seems to have led you to a different conclusion than the one I came away with.

I'll have to go back to reread it.  My first impression was that the rigors of launch caused the part to change in flight, so that it could no longer meet the requirements of its role.  However, your interpretation is that the rigors of launch caused more demand to be placed on the part than the engineers had anticipated.   

Thanks for providing an alternative interpretation.

Edit#1: There is a third interpretation I'll be looking for ... that is that the parts coming from the manufacturer were out of specification, but not enough to fail in the "normal" ground test.  The article does state that (as far as the analysts could determine) there were no failures in manufacturing.

However, if a part was at the weak and of acceptable, and the in-flight current demands were at the outer edge of what was expected, then failure could occur.

I am reminded of the failure of an early Falcon 9 ... a strut failed under load.  SpaceX had procured the struts from a vendor, and the same struts had performed flawlessly in a number of earlier flights.  I'd have to research that incident to be sure, but I'll bet that stress testing that part before it is inserted into a Falcon 9 is part of the process since that expensive failure.

(th)

Last edited by tahanson43206 (2020-07-31 20:41:44)

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#7 2020-07-31 21:22:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

single electrical connection of a battery pack in the upper stage failed. This disconnection severed a vital source of power to the rocket's components, triggering the engine to stop blasting, the rocket body to slow, and the mission to fail.

A connection like this becomes resistive causing while failing not fully disconnection would cause that connection to slow burn making that power loss to continue until no power flows.

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#8 2020-08-01 08:36:45

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,077
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Re: Rocket Lab's Electron Rocket

It's very hard to get technical info out of a news release,  because the reporters who wrote it are not generally technically literate,  or writing for a technical audience.  However,  I did get a sense of the nature of the failure from the comments of the CEO as reported in the news article.

It would seem that the design of the ground test was such that it did not last long enough to reveal the overheating issue.  Had the test been longer by several minutes,  the connector failure would have been revealed. 

This sort of thing often happens in development work,  development in the sense that it's a new product,  fresh from being developed,  and there can be no guarantees until it has been in service a while,  and its remaining faults revealed.

It would only be speculation to comment on why the connector overheated over time.  The article/CEO comments do not address that.  But it occurs to me that it might have something to do with heat transfer (being a thermal failure),  and vacuum conditions (being during a second stage burn). 

There are only 3 ways for a hot thing to shed heat:  by radiation,  by convection,  and by conduction.  In vacuum,  convection goes away,  and the unshed heat associated with it builds up in the hot thing,  over time.  It gets hotter.  If convection was small compared to the other two,  then this buildup is slow with time.  But it does build up.

If the ground test was conducted in the atmosphere,  it may have falsely indicated the conduction/radiation cooling design was OK,  when it wasn't really,  because of the small bit of extra cooling afforded by limited convection down in the atmosphere.  Just speculation.

GW

Last edited by GW Johnson (2020-08-01 08:37:15)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#9 2020-08-01 09:18:05

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

If its not due to a loosening connection then it comes back to surface pad area for conduction and wire guage.

https://www.solaris-shop.com/content/Am … 0Table.pdf

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#10 2020-08-02 10:10:55

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,077
Website

Re: Rocket Lab's Electron Rocket

As I said,  that's only my speculation.  But in addition to contact area and wire gauge,  there is also heat sink size.  The adjacent structure acting as heat sink might be too thin,  or just not massive enough.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#11 2020-08-03 13:39:50

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,077
Website

Re: Rocket Lab's Electron Rocket

I saw something about the connector problem today in a story that indicated the FAA was pretty near ready to let them try again,  with the implication that both outfits understood the problem and how to fix it.

The story's description of the problem was confused at best,  except that it did have to do with some connector making intermittent,  then no,  contact. It was a high-power connection,  because they said it ran the turbopumps.  Had to be very big wires and hardware.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#12 2020-09-05 21:33:00

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 19,690

Re: Rocket Lab's Electron Rocket

Rocket Lab secretly launched its own satellite designed to go to the Moon

Photon is based on Rocket Lab’s “Kick Stage,” which is a mini rocket designed to boost satellite payloads into their final circular orbit once Electron has brought them to space. However, rather than just packing a propulsion system, Photon will carry additional electronics, orientation sensors, power generation units and instruments like cameras. That means that Photon can act as a satellite itself so that clients don’t need to contract third-party providers to design and build them.

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