FAILURE: SpaceX Falcon I Launch III - August 2

[jabe]

Am I correct that there was a second camera inside the payload fairing that provided coverage for that separation event? It seems the down-facing camera must-have been fried by the 2nd stage ignition.

In the second launch video it has the same thing.  I figure it is a mirror that changes the direction of the camera view to see the fairing then switches back.hence the pause in between the views but I'm probably all wet on that

it is a great video..the vid from ground is an added bonus.  I hope they have other angles
If some one is making a documentary of the behind the scene goings on at Spacex during the past few years sign me up for a copy of it now.  The spaceship1 documentary Black Sky is great..this would be even better!!
jb

[stockman]

I would like to thank Elon for releasing this video. It is better quality than I could have hoped for and is very much appreciated. I know there is a lot of criticism from armchair engineers here that criticise this company at what seems every turn... one of those is regarding their PR and secretive behaviour however releasing this video so shortly after the event is definitely an improvement over the last launch where all videos I have seen stop at the 5 minute mark but yet they have video going all the way to orbit. (Yes I would love to see that one).

However, beggers can't be choosers... I appreciate the attempt here at opening up the gates a bit (which they are under no obligation to do). My opinion is thank you for the great view and I wish you the best of luck on launch 4 -

btw - I for one love the last two launch attempts where you had an abort and then recycle within the same launch window - I am no "risk adverse" engineer so I think it shows a lot of guts to show the robustness of the system which allows you to do that. Well done imo.

[aero313]

Is the roll oscillation I'm seeing usual for a launch?  When you wach the video, the vehicle looks like it rolls clockwise for about a second, then corrects back to over the next second, then rolls, then corrects ...  I can see that causing a few challenges during flight...

It depends on the vehicle.  After finally watching the video, even I would say that the roll is a nit.  It appears to simply be limit cycling of the roll control system (the turbine exhaust).  It may be that the regen engine induces more roll torque that the ablative due to the pattern of the tubes, and its possible that they neglected to change gains in the control system, for example, but some LVs (such as Taurus, for example) don't even have or need roll control on the first stage.  Modern IMUs are fast enough to resolve the roll and follow it with the TVC actuators.

[Antares]

Also, why does the exhaust continually get darker as the rocket ascends? Are they changing the mixture to increase fuel burn-up?

SWAG: The mixture ratio may or may not change, but it tends to be fuel-rich, so some fuel is remaining in the exhaust.  This burns in air, when there's air, and not when there's not.

Ahhh! Makes perfect sense.

I'm going to try something a little more nuanced.  As the rocket ascends, the plume undergoes greater expansion.  An expanding gas cools.  So when it expands more, it cools more.  So the unburned fuel and soot is more visible in a wider, cooler plume.

[yinzer]

It depends on the vehicle.  After finally watching the video, even I would say that the roll is a nit.  It appears to simply be limit cycling of the roll control system (the turbine exhaust).  It may be that the regen engine induces more roll torque that the ablative due to the pattern of the tubes, and its possible that they neglected to change gains in the control system, for example, but some LVs (such as Taurus, for example) don't even have or need roll control on the first stage.  Modern IMUs are fast enough to resolve the roll and follow it with the TVC actuators.

Depending on how much roll you have, naturally.

A solid with one nozzle should produce minimal roll disturbances; misalignment of a gas generator exhaust will produce bigger ones, and a helically wound nozzle will produce even bigger ones.

Thinking about it, the roll moment of inertia of a solid rocket stage should be much higher than a liquid stage throughout the entire flight.  Not sure if it's enough to make a difference or not.

[Yegor]

On the video the first stage pushed the second up to 6 seconds after MECO.
How many seconds there should be a delay between MECO and stages separation?
Is it OK to have stages separation 6 seconds after MECO?

[Swatch]

Where are you getting 6 seconds?

[Dalon]

Where are you getting 6 seconds?

I gather he's referring to the video.  MECO at 2:55, stage one is still in contact with stage two until about 3:00.

Somewhere between 5 and 6 seconds.

That said, I'm watching the video with VLC and it doesn't like the .ASX video format one bit.  The time count is a few seconds different each time I play the video.  Still 5 seconds seems about right. 

[Jim]

On the video the first stage pushed the second up to 6 seconds after MECO.
How many seconds there should be a delay between MECO and stages separation?
Is it OK to have stages separation 6 seconds after MECO?

It takes what ever it is needed.  There is no hard rule

[josh_simonson]

You can't really see from the video if the first stage is still pushing against the second stage, or if they're just stuck together.  Even after any fuel/oxidizer has burned, simply the vapor pressure of boiling fuel coming out of the engine probably gives it a bit of thrust that would hold them together for a while.  They only have to wait long enough for the transient to die down enough that separation gives them enough room to fire the engine.

From their statement they were able to see what was going on through the chamber pressure monitors, so depending on how long the monitors transmitted (they may have cut off at sep) they may have a very good idea how the transient looks in vacuum.

[Zonarius]

Were spacex going to try to recover the first stage of this flight
or have they given up trying to reuse the f1 stages?

[Dalon]

Were spacex going to try to recover the first stage of this flight
or have they given up trying to reuse the f1 stages?

I read somewhere that they did plan to recover stage one, but stage two's engines fried the chutes.

[just-nick]

Did anything happen to that video?  I try to hit the link and get nothing behind it...   Not calling "CONSPIRACY!" just annoyance...I was excited to see something making it worth getting up this early.

 --N

[Chris Bergin]

Did anything happen to that video?  I try to hit the link and get nothing behind it...   Not calling "CONSPIRACY!" just annoyance...I was excited to see something making it worth getting up this early.

 --N

Ehhh? Still working for me:

video is now up...
launch
found when clicking picture at update

[aero313]

It depends on the vehicle.  After finally watching the video, even I would say that the roll is a nit.  It appears to simply be limit cycling of the roll control system (the turbine exhaust).  It may be that the regen engine induces more roll torque that the ablative due to the pattern of the tubes, and its possible that they neglected to change gains in the control system, for example, but some LVs (such as Taurus, for example) don't even have or need roll control on the first stage.  Modern IMUs are fast enough to resolve the roll and follow it with the TVC actuators.

Depending on how much roll you have, naturally.

A solid with one nozzle should produce minimal roll disturbances; misalignment of a gas generator exhaust will produce bigger ones, and a helically wound nozzle will produce even bigger ones.

Thinking about it, the roll moment of inertia of a solid rocket stage should be much higher than a liquid stage throughout the entire flight.  Not sure if it's enough to make a difference or not.

Actually, the biggest problem on Taurus was aero torques from raceway misalignment.  We hit something like 8 RPM on the first flight.  Back to Falcon, the roll was an oscillation and the rate was not enough to concern me, anyway.

[William Graham]

Did anything happen to that video?  I try to hit the link and get nothing behind it...

Ehhh? Still working for me:

Which browsers are you using? It seems to work in IE but not Firefox.

[jongoff]

Which browsers are you using? It seems to work in IE but not Firefox.

I watched it just fine in FireFox 3.01

~Jon

[just-nick]

Which browsers are you using? It seems to work in IE but not Firefox.

I watched it just fine in FireFox 3.01

~Jon

Picky web server syndrome.  Just got it to work fine off IE7 at work which normally crashes if I breath too loudly.  Safari at home was no joy, though.  Thanks all.

[iamlucky13]

Actually, the biggest problem on Taurus was aero torques from raceway misalignment.  We hit something like 8 RPM on the first flight.  Back to Falcon, the roll was an oscillation and the rate was not enough to concern me, anyway.

Interesting information...

The Falcon oscillations definitely seemed to increase with altitude, so I don't think it was aerodynamic in this case. Moreover, since I don't remember seeing this on flight 2 the regen plumbing really seems like the best theory.

It seemed like the roll control just ignored it until it hit a threshold, then overcompensated slightly. Hopefully just a minor tuning of the controller?

It was certainly interesting to see the response time of the actuators.


PS - Rats...I'm also having trouble with the video. It's connecting ok, but it won't buffer properly for my slow connection and I can't save it to disk. Video formats and encapsulation are a complete zoo these days.

If it helps anybody, you can go a layer past the .asx file, which basically is nothing more than an xml playlist that points here:

mms://a570.v22165a.c22165.g.vm.akamaistream.net/7/570/22165/v0001/spacex.download.akamai.com/22165/F1-003.wmv

(copy and paste...the forum software appends an errant "http://" on it when I try to link it)

[marsavian]

There's a nice quality downloadable 18MB .wmv version here

http://forum.nasaspaceflight.com/index.php?topic=13944.msg305447#msg305447