SpaceX Test Rocket Explodes After McGregor, TX Launch

[rabar10]

A highlight in the recent NasaSpaceFlight article regarding the last-minute delay of the AsiaSat-6 launch touched on this F9-R McGregor "fiery anomaly":

In explaining the details behind the problem that occurred with the F-9R Dev-1 (L2), sources stressed that any similar issue with the Falcon 9 v1.1 tasked with the ASIASAT-6 launch would not have resulted in the failure observed in Texas.

In fact, the same issue would have resulted in the Falcon 9 v1.1 aborting and safing in-situ on the launch pad. This reason this did not happen for the F-9R Dev-1 is because she does not lift off from a regular launch pad and thus does not have the hold down posts to stop the rocket from lifting off in an off-nominal condition.

Looks like the failure mode would have been detected in a static fire or during a commercial launch, before the hold-downs were released.

 

[chickensevil]

Article also clarifies that the test rocket wouldn't have suffered the fate it did if not for the lack of clamps to hold the rocket in place.

 

[HVM]

Update on AsiaSat 6 Mission

SpaceX has decided to postpone tomorrow's flight of AsiaSat 6. We are not aware of any issue with Falcon 9, nor the interfaces with the Spacecraft, but have decided to review all potential failure modes and contingencies again. We expect to complete this process in one to two weeks.

The natural question is whether this is related to the test vehicle malfunction at our development facility in Texas last week. After a thorough review, we are confident that there is no direct link. Had the same blocked sensor port problem occurred with an operational Falcon 9, it would have been outvoted by several other sensors. That voting system was not present on the test vehicle.

What we do want to triple-check is whether even highly improbable corner case scenarios have the optimal fault detection and recovery logic. This has already been reviewed by SpaceX and multiple outside agencies, so the most likely outcome is no change. If any changes are made, we will provide as much detail as is allowed under US law.

-- Elon Musk

http://www.spacex.com/news/2014/08/26/update-asiasat-6-mission


I don't know how this is related 'to the lack of clamps'. A blocked sensor would be detected during a clamp down -> abort. But without voting this would not work (dev1)?

 

[chickensevil]

http://www.spacex.com/news/2014/08/26/update-asiasat-6-mission


I don't know how this is related 'to the lack of clamps'. A blocked sensor would be detected during a clamp down -> abort. But without voting this would not work (dev1)?

My guess is that *IF* there was a fault that prevented something from working correctly, they would have had the clamps to abort the launch. At the same time the message from Elon clarifies further that there are additional sensors on the F9 that would have *ALSO* caused the rocket to launch without problem. The way I read this, there are many more redundancies and backups and abort sequences that they have at their fingertips on the actual launch vehicle that they didn't put on the dev1 rocket.

But, the clamps have been called out before (and I believe have been used before) as a means to abort a launch should they not have all systems go when they hit the 0 second release. (If I am not mistaken engines fire at like t-3... so the clamps hold it in place for a couple seconds to ensure everything is firing on all cylinders). Given the free standing nature of both grasshopper and F9R dev1 they clearly don't have the clamps.