Actually, even though the interstage is definitely catching some of the exhaust plume, the rolling definitely starts before the second stage lights up.
Here's a question for someone who might know - when the 9 Merlins shut down, what happens to the angular momentum stored in the pumps? Do they spin on regular bearings or something fancier like air bearings? Any chance some knows how much the rotors weigh and how fast they are spinning, and most importantly - in what direction they are mounted?
Maybe it's just me.... but I'm not seeing the interstage part of the video or the separation from inside the interstage. Was the video edited again?
I downloaded the HD version of the clip with the interstage split screen. Sharing it would be tricky, though, unless someone has an easy place to upload it.
I wonder if someone posted the wrong video and had to do a quick swap before the boss found out...
Edit: Go for it, start the thread.
FWIW, I thought that Mvac's Isp was in the range of 305-310s, but I admit it's been a while since I've bothered to check SpaceX's Falcon-9 page for updates on engine performance.
Quote from: Ben the Space Brit on 01/06/2011 10:20 pmFWIW, I thought that Mvac's Isp was in the range of 305-310s, but I admit it's been a while since I've bothered to check SpaceX's Falcon-9 page for updates on engine performance.IIRC, it was originally 342, then listed as 338 before the second F9 flight. Presumably first flight performance was a little lower than expected.Non-vacuum Merlin's vacuum Isp is 304.That puts the trimmed Mvac somewhere between 305 and 337. Given the exit plane area wasn't hugely reduced, I would guess somewhere north of 325.
...The important thing, for the moment, is the top of that spreadsheet, the propulsion numbers: I'm not sure if what I'm calling of 'block2' is still the current expectation or not. In the same way, I'm not sure if what I'm calling of 'block1' is or not close to the current development state of the engines (as used in the recent COTS demo1 flight)....Thanks,António
Seems there is a lot of process engineering bickering going on about Spacex. Just reminder that Nasa HSF is not immune from process failure...