Rocket Science

[Jim]

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. 

[Rocket Science]

Superb engineering video Jim, thanks for posting it.

~Robert

[Silmfeanor]

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

[Jim]

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.

[Jim]

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.

[Mike_1179]

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.

[Art LeBrun]

Great stuff, Jim. Engineering films are always instructive. Thanks.

[Jim]

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

[Jim]

Also notice that it is an oscillation.

[savuporo]

Pet peeve : this is rocket engineering, not rocket science. In other news, we need more rocket engineers.

[mtakala24]

Isn't the safety factor usually 1.4 in manned systems/vehicles?

[Jim]

Isn't the safety factor usually 1.4 in manned systems/vehicles?

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

[JWag]

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?

[Jim]

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

[Chris Bergin]

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!

[JonSBerndt]

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.
 

[MP99]

Pet peeve : this is rocket engineering, not rocket science.

I'd wondered about that, too.

cheers, Martin

[spectre9]

Great video Jim. A real class act around here. 

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

[Jim]

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

[Hodapp]

   Very cool stuff!!!
I need to get back into L2 status again!
I could watch this stuff all day long too...

Thx, Jim!