Wednesday, March 21, 2007

SpaceX's Successful Test, Almost Successful Launch

Congratulations to SpaceX for their very close to successful Falcon 1 launch.

I am fortunate enough to be in a time zone where the launch time was quite convenient - around 10am. I watched the webcast yesterday and today, including the last moment abort. I would like to comment at this stage that the coverage at spaceflightnow.com was excellent. In fact for much of the time during the lead up to the launch and during the flight I had the browser window open to the spaceflightnow Falcon 1 status page, and the streaming webcast showing in a window next to it - not quite a mashup but good enough.

Spaceflightnow also has now posted quite a good summary of the launch. Originally I had thought that the second Kestrel burn was to finish orbit insertion by circularizing the orbit, but it seems from the spaceflightnow article that it was for demonstration purposes only. This means that if the Kestrel upper stage had continued to function properly for its first 6 and a half minute burn, Elon would have been celebrating a successful launch right now. As it stands, it appears that something caused it to spin up like a top which in turn, through an unknown event sequence, (such as propellant being pushed to the sides of the tank) caused the engine to shut down and, judging from the video, possibly pushed the TVC system beyond its limits.

Elon Musk said at the press conference that no additional test flights will be required before they launch a commercial payload. From a strictly engineering point of view I'm not sure this is the best decision, especially since SpaceX missed out on some important technology demonstrations, such as the Kestrel second burn, and simulated payload ejection. However, to be somewhat cynical, it makes sense from a business perspective. Assuming Elon has funds for one more test launch up his sleeve, he probably wants to keep it in reserve just in case he runs out of willing customers. Then, having achieved a final successful test flight he could gather a second round of customers. However, if he uses it too early and has another failure, some of his customers could pull out.

Something else that occurred to me is that Kestrel must seem a bit of a technology dead end to SpaceX. I'm not sure where I saw it but I remember Elon saying that he regrets not developing a regeneratively cooled second stage. Also Elon Musk has set his sights on heavy lift. The Falcon 1 first stage will be used as a clustered system for Falcon 9, but I assume Kestrel won't have a place in SpaceX's future designs. Perhaps this has resulted in some lack of attention to Kestrel, but that's pure speculation.

In any case, SpaceX's future looks bright after their latest attempt. Certainly they have demonstrated some technology innovations that are likely making customers such as USAF hungry for more. Their rapid turnaround from last moment launch abort to the next launch attempt was particularly impressive - around 1 hour I think. The winds of change are starting to blow a little harder in the US launch industry.

4 Comments:

At 6:40 PM , Anonymous Brad said...

Clarifications re: Merlin, Kestrel, second stage

"I'm not sure where I saw it but I remember Elon saying that he regrets not developing a regeneratively cooled second stage. Also Elon Musk has set his sights on heavy lift. The Falcon 1 first stage will be used as a clustered system for Falcon 9, but I assume Kestrel won't have a place in SpaceX's future designs. Perhaps this has resulted in some lack of attention to Kestrel, but that's pure speculation."

Musk has stated he regreted not using regenerative cooling on the Merlin 1st stage engine. The original Merlin used ablative cooling, the latest redesigned Merlin uses regenerative cooling and has higher thrust. (Musk has also said he regretted using pintle inector design for the Merlin)

Originally two Kestrel engines were going to be used for the second stage of the larger Falcon 5 rocket, but that has changed. Now the Falcon 5 and the Falcon 9 will use a modified Merlin engine for their second stages. This new Merlin is optimized for vacuum operations with a larger expansion nozzle. A post at SpaceX even lists a much higher 155,000 lbs of thrust for the upper stage Merlin.

For future even higher performance rockets Elon Musk has mentioned a Merlin 2 engine which would be in the same thrust class as the Saturn F-1 engine, and the possiblility of developing a liquid hydrogen fuelled upper stage Musk said could boost the LEO payload of the heavy version of the Falcon 9 to as much as 50 tons. Presumably the new hydrogen engine would be an adaptation of the 2nd stage Merlin engine which uses RP-1 for fuel.

 
At 6:43 PM , Anonymous Anonymous said...

Clarifications re: Merlin, Kestrel, second stage

"I'm not sure where I saw it but I remember Elon saying that he regrets not developing a regeneratively cooled second stage. Also Elon Musk has set his sights on heavy lift. The Falcon 1 first stage will be used as a clustered system for Falcon 9, but I assume Kestrel won't have a place in SpaceX's future designs. Perhaps this has resulted in some lack of attention to Kestrel, but that's pure speculation."

Musk has stated he regreted not using regenerative cooling on the Merlin 1st stage engine. The original Merlin used ablative cooling, the latest redesigned Merlin uses regenerative cooling and has higher thrust. (Musk has also said he regretted using pintle inector design for the Merlin)

Originally two Kestrel engines were going to be used for the second stage of the larger Falcon 5 rocket, but that has changed. Now the Falcon 5 and the Falcon 9 will use a modified Merlin engine for their second stages. This new Merlin is optimized for vacuum operations with a larger expansion nozzle. A post at SpaceX even lists a much higher 155,000 lbs of thrust for the upper stage Merlin.

For future even higher performance rockets Elon Musk has mentioned a Merlin 2 engine which would be in the same thrust class as the Saturn F-1 engine, and the possiblility of developing a liquid hydrogen fuelled upper stage Musk said could boost the LEO payload of the heavy version of the Falcon 9 to as much as 50 tons. Presumably the new hydrogen engine would be an adaptation of the 2nd stage Merlin engine which uses RP-1 for fuel.

 
At 1:12 AM , Blogger David Riseborough said...

Thanks for the info. There's always a risk with saying "I remember" rather than checking the source. I guess that means Elon Musk is happy with the Falcon 1 second stage design the way it is, although it looks like it isn't on the development path for any of the larger vehicles.

 
At 12:27 PM , Anonymous Anonymous said...

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