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 stagingPersonally 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?
