SpaceX Falcon 1, Launch 4… live from Kwajalein

The launch live webcast link is here..

2322. This could be an interesting evening. As you know, the third launch failed at staging. It was quickly determined that the cause of this was a ‘burp’ from the Merlin engine after shutdown. There is some fuel and oxidizer left in the system when the engine shuts down, and in a regen engine there will be a bit more because the oxidizer is warmed and the nozzle cooled by running it through tubes around the outside of the bell. When they checked test data they found this had actually occurred in a ground test but the transient was ‘down in the weeds’ at sea level pressure and had not been noticed as it was perhaps only a tenth of an atmosphere of pressure and thus hidden in the 1.0 sea level pressure. At high altitude the ambient was near zero so the burp was significant. What happened then, was that after a perfect first stage burn and a flawless staging… the engine burped perhaps 2 seconds after sep and was enough to cause the first stage to ram the second stage just as it was ready to fire.
For flight four they have raised the delay from first stage cutoff to stage separation from 3 second to 5 seconds to account for this. There were no other flight anomalies of any significance on flight 3; flight 2 with the earlier Merlin regen engine has successfully staged and fired the Kestrel engine almost to second stage cut off so I am hopeful we will see a successful orbital insertion today.

2349. Fueling is in progress and near completion, or at least as near as they will go this early. The final top off will not occur until later in the launch. I am wondering if this might be partly to prevent the RP1 (kerosene) from chilling down as much as it did on a previous flight. Ah, the webcast has just now gone live.

0011. They are into the terminal count but they have been giving us loads of talking head chatter instead of the interesting stuff. I’d much rather listen to the real internal loop than people assigned to interpret to us. There is in any case only about 5 minutes to go.

0013. As you can see if you are watching the video, the tower is retracted, and we are now hearing the real control loop. 2:30 to go! Launch director gave a green, range is green, about 1 minute to go!

0018. She’s going up and looking great so far! Max Q… first stage going great. Getting close to time for pitch over and MECO.

0021. Second stage is burning beautifully!!!!!! There is no roll problem this time. Now we wait 4 minutes as she goes down range.

0022. No sign of roll anomalies like on flight 2. The slosh baffles are doing their job. 315 km high now…

0024. Almost there… the bell glows red hot but it is built for that. We now have lost signal, probably due to range.
We are waiting now for whether we got the orbital insertion…. and…. THEY HAVE DONE IT!!!!!!

0043. They are in orbit with their dummy satellite. The only things we need to hear now is whether they get a successful recovery of the 1st stage from the Pacific. It should have come down on parachutes but I don’t expect I will hear about that until ‘tomorrow’. I feel a bit like Elon… I hardly know what to say. I must admit that I was here screaming like the SpaceX employees and I now feel just limp, tired and very, very happy. So… another Falcon 1 launch latter this year and then on to the much larger Falcon 9 next year!