Author Topic: Rocket Science  (Read 13674 times)

Offline Jim

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Rocket Science
« on: 04/20/2012 11:22 am »
I made this short clip to show some of the work that goes into "rocket science".  The clip is also a teaser for some of the material that will be on L2 (which I hope is ok with Chris).

The clip is from some engineering cameras on a Titan IVB launch and has 3 views.

The first view is for context and to show the forward SRM attachments.  The SRM's for the Titan IV lift from the bottom and so the forward attachment is basically sway braces to counter side loads and rotation.

The next view zooms in on the forward attachment of one of the SRM's.  As ignition of the SRM occurs, two things happen:  The SRM elongates from the internal pressure and to a lessor extent, the booster starts rising before the core as it lifts it due to system elasticity.   The engines of the core of the Titan IV do not fire until at altitude and so it is "dead" weight.

The final view further demonstrates this phenomena.  It is close up of the slip joint between the booster and core. 
« Last Edit: 04/20/2012 12:06 pm by Jim »

Offline Rocket Science

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Re: Rocket Science
« Reply #1 on: 04/20/2012 11:26 am »
Superb engineering video Jim, thanks for posting it.

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Offline Silmfeanor

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Re: Rocket Science
« Reply #2 on: 04/20/2012 03:59 pm »
woah, that was some difference in movement between the boosters and the core.
First time I hear about booster elongation from ignition - to be expected I guess. How much does a booster elongate from internal pressure when ignited? how do you account for this elongation? Some form of seals or material that just stretches a bit?

Thanks, I love stuff like this! Looking forward to the L2 movie :D

Offline Jim

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Re: Rocket Science
« Reply #3 on: 04/20/2012 04:13 pm »

First time I hear about booster elongation from ignition - to be expected I guess.

yes, you have heard about this before, just in another context.  Joint rotation shuttle SRM's and Challenger.  SRM's also expand radially a little.
« Last Edit: 04/20/2012 04:14 pm by Jim »

Offline Jim

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Re: Rocket Science
« Reply #4 on: 04/20/2012 04:15 pm »
how do you account for this elongation? Some form of seals or material that just stretches a bit?


It was a composite case for the SRM, but steel casings do it also.

Offline Mike_1179

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Re: Rocket Science
« Reply #5 on: 04/20/2012 04:33 pm »
So when someone says "How hard can it be to stick a known booster on the side of a known launch vehicle to increase how much it can lift?" do you just show them this video?

What sort of factor of safety is generally used in launch vehicle design?  I would guess that because mass is so critical, you're in the 1.2-ish range.  When designing a dynamic system like this in other industries (my day job), we'd have a SF closer to 3.0 due to the unknowns under that type of high load, high acceleration environment.  Some of our empirical models don't account for what's seen in that video as accurately as you'd want, so we reduce risk by adding margin (which usually involves making things larger / stronger).

Not being able to do that in rockets is probably the biggest challenge I can think of.

Offline Art LeBrun

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Re: Rocket Science
« Reply #6 on: 04/20/2012 04:44 pm »
Great stuff, Jim. Engineering films are always instructive. Thanks.
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Offline Jim

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Re: Rocket Science
« Reply #7 on: 04/20/2012 05:28 pm »

What sort of factor of safety is generally used in launch vehicle design?  I would guess that because mass is so critical, you're in the 1.2-ish range. 

1.25

Offline Jim

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Re: Rocket Science
« Reply #8 on: 04/20/2012 05:31 pm »
Also notice that it is an oscillation.

Offline savuporo

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Re: Rocket Science
« Reply #9 on: 04/20/2012 05:31 pm »
Pet peeve : this is rocket engineering, not rocket science. In other news, we need more rocket engineers.
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Offline mtakala24

Re: Rocket Science
« Reply #10 on: 04/20/2012 05:58 pm »
Isn't the safety factor usually 1.4 in manned systems/vehicles?

Offline Jim

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Re: Rocket Science
« Reply #11 on: 04/20/2012 06:03 pm »
Isn't the safety factor usually 1.4 in manned systems/vehicles?

That is NASA's requirements and a point of contention.

Offline JWag

Re: Rocket Science
« Reply #12 on: 04/21/2012 01:30 pm »
Thanks for this.  I could watch this kind of thing all day!

What is the purpose of the faired-over "connection" between the booster nosecones and the core, above the slip-joint?  Avionics?

Offline Jim

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Re: Rocket Science
« Reply #13 on: 04/21/2012 01:37 pm »
What is the purpose of the faired-over "connection" between the booster nosecones and the core, above the slip-joint?  Avionics?

Electrical connection between booster and core

Online Chris Bergin

Re: Rocket Science
« Reply #14 on: 04/21/2012 04:46 pm »
I made this short clip to show some of the work that goes into "rocket science".  The clip is also a teaser for some of the material that will be on L2 (which I hope is ok with Chris).

Yes sir! ;D
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Offline JonSBerndt

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Re: Rocket Science
« Reply #15 on: 04/21/2012 04:51 pm »
Pet peeve : this is rocket engineering, not rocket science. In other news, we need more rocket engineers.

Heh. Did you read Neufeld's Von Braun biography preface, too? ;-)
 
Nice video.
 

Offline MP99

Re: Rocket Science
« Reply #16 on: 04/21/2012 06:32 pm »
Pet peeve : this is rocket engineering, not rocket science.

I'd wondered about that, too.

cheers, Martin

Offline spectre9

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Re: Rocket Science
« Reply #17 on: 04/22/2012 01:32 am »
Great video Jim. A real class act around here.  8)

Love the core spring. Had no idea such a movement was happening.

Offline Jim

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Re: Rocket Science
« Reply #18 on: 04/22/2012 04:48 am »
Here is another clip;

Notice the flexing of the boosters as they react to wind and the dimpling of the core skin as it reacts to the boosters

Offline Hodapp

Re: Rocket Science
« Reply #19 on: 04/22/2012 05:00 am »
 :D  Very cool stuff!!!
I need to get back into L2 status again!
I could watch this stuff all day long too...

Thx, Jim!
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