Talk-Polywell.org

Why would ground testing a used booster be any different from ground testing an unused booster?
I consider the risk lower than it was for the first launch of an upgraded F9 (which they do all the time).

A new booster has not been stressed by a flight cycle. These stresses are not the same, especially when encountered all together, as those endured in ground testing. While ground testing can (and is a means for) testing boosters, in this case, I think an upinstrumented booster on a recycle flight would tell them more and faster than a ground test regime. They could focus the extra instrumentation on suspected critical stress areas based on inspections and modeling.

And again, these are just my thoughts, they will do as they see fit. I am not saying you are wrong, I am offering an alternative approach in which I think the overall risk has potential to be lower, and that may return more information faster on the cumulative flight stresses for recycled boosters.

Risks are in proportion to benefits. SpaceX apparently have highly instrumented rockets- this allowed them to quickly pinpoint the failed component in their RUD launch last year. Also, ground testing puts stresses on the spacecraft that again presumably gives substantial information and predictive performance limits. The previous launch of the used rocket even tests for the failure that doomed a previous virgin launch- that was not revealed with ground tests.

And risk is money. Assuming the satellite is a spare, then loss would delay replacement in a constellation of satellites but not necessarily compromise performance goals, with plenty of time for a repeat launch if needed. The cost of the satellite would be lost, but that is what insurance is for. A higher premium could be easily offset by a bargain launch price. The satellite company may stand to lose almost nothing and if successful, save several million dollars in the cost of placing the satellite in orbit. Space X is the only one at some risk, in terms of reaching stated goals. Some of the most interesting action may be with the insurers trying to asses risk.

Dan Tibbets

SES will not only save money on this launch but on the many subsequent launches they will do with SpaceX.

My money saving scenario is supposition but it does seem likely.

I also speculate that using a used first stage with minimal modifications, appropriate ballast, etc. could be used to boost the Dragon II for spacecraft escape testing. I think Space X currently plans to use a modified second stage for this test, but this alternative would seem to be attractive, at least as opposed to a dummy launch, if a comercial customer could not be found. With modifications this second stage may be more expensive than a recycled first stage, especially if the first stage can again be recovered. At this late date, though, the plans may be too far along to abandon (money already spent). Ideally you would test and validate the first stage reusability and Dragon II escape system in the same mission. Even if the first stage failed in the latter part of the boost- well, it is a test of the Dragon escape system after all!

Dan Tibbets

D Tibbets wrote:My money saving scenario is supposition but it does seem likely.

I also speculate that using a used first stage with minimal modifications, appropriate ballast, etc. could be used to boost the Dragon II for spacecraft escape testing. I think Space X currently plans to use a modified second stage for this test, but this alternative would seem to be attractive, at least as opposed to a dummy launch, if a comercial customer could not be found. With modifications this second stage may be more expensive than a recycled first stage, especially if the first stage can again be recovered. At this late date, though, the plans may be too far along to abandon (money already spent). Ideally you would test and validate the first stage reusability and Dragon II escape system in the same mission. Even if the first stage failed in the latter part of the boost- well, it is a test of the Dragon escape system after all!

Dan Tibbets

SpaceX has to use a first stage with a dummy second stage for that, since they have to simulate the abort at maximum drag during a normal launch. Some people have been speculating that a reused first stage will be used for that. Others claim that SpaceX has already built and set aside a stage for this.

I wonder if it would make more sense to launch the first reused booster with a consumable payload for the ISS ahead of the scheduled ones. Such a payload is very likely a lot cheaper than a satellite and sending one up before it's needed would mean it's loss wouldn't be a big problem if it fails.

Right now, we are really only speculating on what they will do with the first recycle. They will speak more on it for sure.
Good thoughts by all, outlining different perspectives. SpaceX/Musk has yet to reveal the actual plan.
And Musk could push for any option we have outlined, he is a wildcard. Whatever the outcome, we will all have a chance to learn from it.

Grumalg wrote:I wonder if it would make more sense to launch the first reused booster with a consumable payload for the ISS ahead of the scheduled ones. Such a payload is very likely a lot cheaper than a satellite and sending one up before it's needed would mean it's loss wouldn't be a big problem if it fails.

The problem with this may be the cost of the capsule itself. I don't know its cost, but I suspect it may surpass some commercial satellites.

Dan Tibbets

Looks like SpaceX had another lawn dart, or should I say Barge Dart...

Details thin right now, but it looks like the stage made the barge but didn't survive.

The two Sats on stage two are deploying now.

This Falcon 9 landing caused a bit of drama, since SpaceX wasn't sure at first if the vehicle actually made it down in one piece. Once the rocket landed, it shook the drone ship pretty violently, causing the ship's onboard camera to freeze. The last shots of the vehicle before the camera cut out showed the Falcon 9 standing upright on the ship, but there were also some flames around the bottom. Later CEO Elon Musk confirmed that the Falcon 9 suffered an RUD, or a rapid unscheduled disassembly. That's "Musk speak" for an explosion.
Later, Musk said that the problem had to do with low thrust in the one of the rocket's three main engines, and that all the engines need to be operating at full capacity to handle this type of landing. He noted that the company is already working on upgrades to the Falcon 9 so that it can handle this type of "thrust shortfall" in the future.




The video of the landing will be released later, according to Musk, once the company gets access to the drone ship's camera.

"maybe hardest impact to date"





Although, it sure looked like in the video that it stuck, then popped. Meh, soon enough we will have it in HD glory...

Ah for the heady days of Apollo when landing withing a hundred square miles was a good shot,,, not a one hundred square yards

Well, they landed in the right spot alright, but a bit too hard. I am less worried about them fixing the compensation for a failed engine. I am more worried about the reason for the engine failing. If the engines are having problems dealing with the heat of re- entry, then that could be a problem for their goal of rapid reuse.

Wednesday makes for four Falcon 9 launches since April 8, with an average of a little more than three weeks between flights. so that flight every week goal is starting to look better and better.