Falcon 1 - Post Failure thread

[vf500f85]

FYI, Velcro has been conquered for srb's atleast.

Orbital use a thermal blanket for their OSP (Minotaur Vehicles) launches.  They call it the yellow banana.  

[mikejz]

Humm....An structually damaged rocket full of RP-1 and Lox.  I think the recovery crew rather it exploded.

[hyper_snyper]

I found these images off of an environmental assessment of SpaceX's operations on Omelek Island.  I don't know how old this technical drawing is but, as you can see, the engine bay is protected.   The question is would this have had any effect on the outcome of the launch?  

The entire document is an interesting read and I recommend going through it.   The pdf file is right here...

Oh, and if this has been posted before, my apologies.

[Jim]

hyper_snyper - 27/3/2006  7:42 PMI found these images off of an environmental assessment of SpaceX's operations on Omelek Island.  I don't know how old this technical drawing is but, as you can see, the engine bay is protected.   The question is would this have had any effect on the outcome of the launch?  

The entire document is an interesting read and I recommend going through it.   The pdf file is right here...

Oh, and if this has been posted before, my apologies.

Look at the video, it is NOT protected

[hyper_snyper]

Yeah I know, that's my question.  If the engine was covered like it is in those drawings above, would the fire still have happened?

[Jim]

hyper_snyper - 27/3/2006  9:14 PMYeah I know, that's my question.  If the engine was covered like it is in those drawings above, would the fire still have happened?

If you have a crystal ball you would know.  It impossible to really determine things like that unless you have all the facts.

[Kaitsu.]

Wouldn't a fire inside a fairing be even more destructive than without a fairing? The temperature would rise faster and higher inside it. And a fairing could collect an exlosive mix of gasses wich would be vented away without a fairing. This happened some times even in the shuttle.

So a fairing is perhaps not only a good thing. As far I remember the Saturn 1B hadn't any engine fairing in the efirst stage.

So there is also the aerodynamic aspect. What kind of shock waves hit the engine of Falcon 1 at the time of Mach 1? Whell, I guess it did not reach Mach 1 ?

[James Lowe1]

Making sure everyone is up to date with the post-failure information.

Here's the other current SpaceX thread on Falcon 1
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1967&start=16&posts=23

[Avron]

UK Shuttle Clan - 27/3/2006  3:29 AM

Avron - 27/3/2006  12:03 AM

James (Lockheed) - 27/3/2006  12:20 AM

mikejz - 26/3/2006  10:42 PM

I wonder if the flame is a byproduct of the RP-1 fire and the engine shutdown----that the lack of thrust changed the airflow above the engine and caused the RP-1 fire to flare up.  

Possible, although I believe it occured simply too fast for that to be the case. I think we're seeing a critical failure and then a shutdown.

Looks like the vehice has stopped climbing, engine is shutting down, zero trust and its has rotated to a nose down attitude around the centre of gravity (launch phase is vertical), and all we are seeing is the airflow blowing the last flames of the engine in shutdown mode in the opposite direction to the vehicle rotation..

All that in the space of a few milliseconds? (if we are taking about the sudden change of the flame to a plume).

Like the time taken for an engine shutdown?

[Jim]

Kaitsu. - 27/3/2006  9:40 PMWouldn't a fire inside a fairing be even more destructive than without a fairing? The temperature would rise faster and higher inside it. And a fairing could collect an exlosive mix of gasses wich would be vented away without a fairing. This happened some times even in the shuttle. So a fairing is perhaps not only a good thing. As far I remember the Saturn 1B hadn't any engine fairing in the efirst stage.So there is also the aerodynamic aspect. What kind of shock waves hit the engine of Falcon 1 at the time of Mach 1? Whell, I guess it did not reach Mach 1 ?

A fairing "might" have limited air exchange and the fire could have snuffed itsself out.  Or the RP-1 kept leaking and reached the outsidbe and burn something else or......

Usually engine compartments are purged with GN2

Saturn IB has fairings.  Only the engine bells were exposed.

[dmc6960]

Relating to the environmental impact study, it mapped out 4 different options for the island layout.  Anybody know which one of those was built?  Also, in ideas if the F5/9 would use a different pad at a different location, or could the existing pad be rebuilt to accomodate both vehicles?

[Jim]

dmc6960 - 28/3/2006  10:22 AMRelating to the environmental impact study, it mapped out 4 different options for the island layout.  Anybody know which one of those was built?  Also, in ideas if the F5/9 would use a different pad at a different location, or could the existing pad be rebuilt to accomodate both vehicles?

The existing pad is just that, a pad of concrete.  The launcher is just a base that the erector attachs to.

F5/F9 would need new GSE.

[hey you]

Comments offered in the spirit that details make a difference and that it is not necessarily possible to determine which
details are important until after the fact.

First, the environmental impact report that is referenced in this thread is awesome. Thanks for the reference.

However, that does not mean that a review does not generate questions and/or further thought.

Hmmm, approximately 7 or 8 times, two 500 kilovolt generators are mentioned. My comments: kiloVOLTS ?? Gee, hook them
up in series and this will be a megavolt event. (Poor attempt at humor :-) )

A couple of the maps do not show any orientation. They are the ones showing a couple of the launch trajectories. It appears
that north is not at the top (unless I am misreading the map -- an invitation for someone to double or triple check my
observation.) (Another poor attempt at humor: maybe that is why the recovery ship was in the restricted area during the
countdown -- doubt it -- just pointing out a way that ambiguity can lead to error(s).)

The cover photo or art (composite) appears to perhaps have been prophetic. Vehicle on its side with the camera view
facing down from above looking at the island.  SAD!

The risk statement of something like 1 x 10 to the -7 buried in the report leaves questions in my mind. What population is
that supposed to be applied to. Perhaps, but not necessarily, being ridiculous, the earth's population is 6 x 10 to +9.
Over 10 launches, not a good outcome. OK, OK, OK. What I am really asking is how that risk assessment calculation is
supposed to really be done with the information supplied.

Elsewhere, the "low probability" event (failure on the pad or early in flight) seems to have occurred. So much for low
probability events. (Anyone interested in buying a lottery ticket?  -- Another poor attempt at humor).

Supposedly the low probability event would lead to impact in the water. The available information up to now suggests
that at least some of the vehicle or payload kerplunked on land (the reef). Oh well, so much for probabilities. (Anyone
think George Mason will win the NCAA tournament? -- Just asking). Both a low probability event and a landing outside
the area mentioned in the report (although I may have missed it in the skimming of the report, and impact on land is
more than reasonable if the powered flight ends in the first few seconds of powered flight.)

Just a few thought to perhaps generate more thoughts

Once again, thanks for the reference to the report. It made/makes for interesting skimming (possibly good reading, if one
wants to be more ambitious.)


s/ Hey You

[Tap-Sa]

vf500f85 - 28/3/2006  3:48 AM

FYI, Velcro has been conquered for srb's atleast.

Orbital use a thermal blanket for their OSP (Minotaur Vehicles) launches.  They call it the yellow banana.  

Why does all solids rocket need a thermal blanket?

[Jim]

Tap-Sa - 28/3/2006  12:45 PM

vf500f85 - 28/3/2006  3:48 AMFYI, Velcro has been conquered for srb's atleast.Orbital use a thermal blanket for their OSP (Minotaur Vehicles) launches.  They call it the yellow banana.  

Why does all solids rocket need a thermal blanket?

Many reasons:

Help keep the fairing (payload), avionics, or motors at a constant or specified temp

[blueguitarbob]

dmc6960 - 28/3/2006  10:22 AM

Relating to the environmental impact study, it mapped out 4 different options for the island layout.  Anybody know which one of those was built?  Also, in ideas if the F5/9 would use a different pad at a different location, or could the existing pad be rebuilt to accomodate both vehicles?

  From the video, it looks like the launch pad is not at the northern end of the island, so I'd guess either option 1 or 4. Also in appendix B of the report, option 4 is referred to many times as the "preferred alternative". I'm assuming that the layout is option 4.

  By the way, the best part of the report is appendix B. Its the correspondence trail of approval and discussion of the document. If you would like a detailed look at regulatory government in action, and an appreciation for the effort it takes to deal with it, at least skim appendix B.

[aero313]

Tap-Sa - 28/3/2006  1:45 PM

Why does all solids rocket need a thermal blanket?

Most solid propellants have a narrow operational temperature range.  This is due to the high grain stresses at ignition when the case pressurizes.  Overstressing either the propellant or the propellant to insulator bond causes cracks that lead to catastrophic failures.  ICBMs are stored in temperature controlled silos, so there's no need to spend the effort to design for a wide operational temperature range.  It is instructive to note, however, that the three Pegasus motors and the Castor 120 were developed to be launch vehicle motors and thus would not have the benefit of the thermally controlled silo.  These motors have been qualified to operate at low temperatures, which is why Pegasus and Taurus (and the Athena) do not require these blankets.

Note that this is even more evidence that the Pegasus motors were new designs...

[Tap-Sa]

aero313 - 28/3/2006  10:30 PM
  This is due to the high grain stresses at ignition when the case pressurizes.  

Interesting, is this related to grain burn rate? AFAIK solids perform a little worse when cold. (Had hands-on experience in army while fiddling with expendable RPG. It had different sights for summer/winter conditions)

About velcro blanket + solid motors, that combo should work well because there's no cryogenic stuff inside the case. I suspect Falcon blanket failed simply because LOX caused enough air moisture to freeze that it effectively glued the blanket into the wall, plus turned the attachment points into velcro-reinforced iceblocks. (Unless they had proper heaters in place of course)

[aero313]

Tap-Sa - 28/3/2006  3:55 PM

aero313 - 28/3/2006  10:30 PM
  This is due to the high grain stresses at ignition when the case pressurizes.  

Interesting, is this related to grain burn rate? AFAIK solids perform a little worse when cold. (Had hands-on experience in army while fiddling with expendable RPG. It had different sights for summer/winter conditions)

No, it's just the nature of the beast.  Solids tend to run a chamber pressure of around 1100 psi.  The ramp-up from ambient to 1100 psi takes a fraction of a second, and even with graphite wound cases there is significant case expansion.  More importantly, the strain rate in the propellant is quite high.  As with virutally all solids, the propellant is more brittle when cold, so the chances of a crack or bond failure are greater as the temperature drops.  Solids that must function under cold conditions (Pegasus and wing-mounted tactical missiles on aircraft) use a combination of different propellant formulation and strain relief flaps and slots in the grain.

The lower performance when cold is also just the way solids work.  Note, however, that while thrust will be slightly lower when cold, the burn time will be longer.  The result is that total impulse (the area under the curve on a time-thrust plot) remains the same.

[braddock]

blueguitarbob - 28/3/2006  2:04 PM
  From the video, it looks like the launch pad is not at the northern end of the island, so I'd guess either option 1 or 4. Also in appendix B of the report, option 4 is referred to many times as the "preferred alternative". I'm assuming that the layout is option 4.

I haven't looked at the environmental report yet, but maybe this aerial of Omelek helps.  This photo never made the SpaceX web site, but we ran it in a story last year.

 I'm not sure you could lay three Falcon 9's end to end across that tiny island, I don't know how they are going to launch Falcon 9 from there.