credit NASA / click on this image to see a larger version in the same browser window
I never got an answer from NASA to my questions about the schedule, cost, performance and other impacts of the Ares I crew launch vehicle (CLV) staging issue that the Ares project office has given a likelihood risk rating of two but an impact rating of five (the highest) across all the consequence categories. My story was published on the 8 February and three days later this 11 February NASA blog post appears (BTW I didn't write the spiteful commentt) with an image that shows the ullage settling motors in action on the Ares I upper stage assisting with the staging
Personally when I had seen references to J-2X nozzle contact with the first stage I always thought that referred to the upper stage engine's nozzle bumping or getting dragged up the interior side of the interstage as the first-stage slowed with its deceleration motors and the upper stage kept on going
Neither did I think that ullage settling motors would apparently be required to assist quite so literally in staging and not just force propellant (ullage being the remaining propellant) to the bottom of the tanks - I've sent some questons into NASA today to clarify their role
It was not until I read the project office documents back in late January did I realise that recontact literally meant a first-stage hitting an upper stage that couldn't accelerate fast enough to avoid the remaining interstage coming up behind it in the milliseconds after the linear charge cuts through that structure
Seeing the NASA image I wonder how powerful those ullage motors are going to have to be?
Neither did I think that ullage settling motors would apparently be required to assist quite so literally in staging and not just force propellant (ullage being the remaining propellant) to the bottom of the tanks - I've sent some questons into NASA today to clarify their role
It was not until I read the project office documents back in late January did I realise that recontact literally meant a first-stage hitting an upper stage that couldn't accelerate fast enough to avoid the remaining interstage coming up behind it in the milliseconds after the linear charge cuts through that structure
Seeing the NASA image I wonder how powerful those ullage motors are going to have to be?
on February 17, 2009 6:51 PM | Reply
Here is a video of a test firing of the motor.
ullage motors test fire
the motor is about 1' x 4' I could not find any stats for the motor.
on February 18, 2009 4:03 AM | Reply
This ended 2 of Musk's flights. First, the engine nozzle got hit. Second, the 1st stage rammed into the 2nd stage. Amazing the mighty NASA has been reduced to solving the same problems as discount dot com funded programs. You'd think NASA wouldn't have problems like this. They wouldn't worry about gyro drift because they could afford gyros that don't drift, or they wouldn't have screws rusting because they could afford screws that don't rust. Not with today's budgets.
on February 18, 2009 5:06 AM | Reply
Where did you get this awesome graphic? Is there more?
on February 18, 2009 8:54 AM | Reply
The image is from this NASA blog post, I don't know of any more
http://tinyurl.com/cucvcb
on February 18, 2009 10:11 PM | Reply
Remember that the first stage is a solid rocket motor. Therefore it _can't be shut down_ and the staging gets a lot more complicated. Yet another genius element of Ares.