Can anyone speculate on the possible use of the 'divert' pads? I can't really see how they would be used. Unless a rogue alligator wandered on to the primary pad... but even then you'd only need one alternate.
They need 3 for a returning Heavy. The central core will not always land downrange.Plus maybe 1 spare.
The contingency pads would only be utilized in order to enable the safe landing of a single vehicle should last-second navigation and landing diversion be required. There are no plans to utilize the contingency pads in order to enable landing multiple stages at LC-13 during a single landing event."
Quote from: cscott on 01/08/2015 01:16 pmCan anyone speculate on the possible use of the 'divert' pads? I can't really see how they would be used. Unless a rogue alligator wandered on to the primary pad... but even then you'd only need one alternate.They need 3 for a returning Heavy. The central core will not always land downrange.Plus maybe 1 spare.
The scope for this EA is limited to the landing of the first stage of a Falcon 9 vehicle, or a Falcon Heavy single firststage, at LC-13, and the activities to support redeveloping LC-13 into a landing location. This EA does not include amultiple booster landing scenario since only one booster will be landing at this facility during a landing event. ThisEA assumes a normal launch mission of a Falcon vehicle continues forward with the successful separation of thesecond stage and payload, while the first stage begins its landing sequence. Therefore specific details of only thereturning Falcon 9 first stage will be discussed; details of the full vehicle launch/takeoff and potential environmentalimpacts can be found in the 2007 EA and 2013 SEA (USAF 2007, 2013). Launches/takeoffs of the Falcon Heavyvehicle would be addressed in a separate NEPA document.
propellants would be burned to depletion during flight
Complexes at KSC were considered; however, no sites were readily available or within reasonable distances fromthe launch and stage refurbishment location.
Bottom of 2-4:Quote propellants would be burned to depletion during flightDoes this mean the stage can hover until it burns through the rest of the fuel? Or is the whole sequence so exact that they land at the exact moment they run out of fuel?
So this means they already have a site planned where they will refurbish the stages! Does anyone know where exactly? That is the only reference to refurbishment in the doc.
Quote from: Dudely on 01/08/2015 02:29 pmSo this means they already have a site planned where they will refurbish the stages! Does anyone know where exactly? That is the only reference to refurbishment in the doc.Why would it be any different than the places they are using now?
The Falcon Heavy first stage center core and boosters each carry landing legs, which would have the capability toland each core safely on earth after takeoff at some point in the future. After the side boosters separate, the centerengine in each would burn to control the booster’s trajectory safely away from the rocket. The legs would thendeploy as the boosters turn back to Earth, landing each softly on the ground. The center core would continue to fireuntil stage separation, after which its legs would deploy and land on Earth. This document assumes that only one of the two boosters (or one center core) would return to LC-13. A multiple booster landing scenario would require additional infrastructure and study not included as part of this Proposed Action. Figures 2-2 and 2-3 below show the engine arrangement for the Falcon 9 and the Falcon Heavy launch vehicles, respectively. ......It is anticipated that no more than 12 landings would take place per year for the initial five year license.
Quote from: Dudely on 01/08/2015 02:24 pmBottom of 2-4:Quote propellants would be burned to depletion during flightDoes this mean the stage can hover until it burns through the rest of the fuel? Or is the whole sequence so exact that they land at the exact moment they run out of fuel?It can't hover - for several reasons.Thrust - unless the engine is able to be throttled below 40% or so maximum throttle - is too high and exceeds weight.Hovering at ~1M so you can drop onto the pad when the engine cuts out would throw up all sorts of debris, and greatly heat the rocket and legs due to the blowback flames licking over the structure.Hovering for an extended period leaves it more vulnerable to any upset - for example, wind.That said - elsewhere the residual fuel is mentioned at 15! gallons RP1 and 150 gallons LOX.Which seems really rather optimistic.I also note in the document no mention of BargeX.Though that was announced a month later.
Quote from: Jim on 01/08/2015 02:51 pmQuote from: Dudely on 01/08/2015 02:29 pmSo this means they already have a site planned where they will refurbish the stages! Does anyone know where exactly? That is the only reference to refurbishment in the doc.Why would it be any different than the places they are using now?Because until now, we couldn't answer whether or not they were going to truck each stage back to Hawthorne for a tear down and refurbishment. Now we can drive a stake in the ground because we've got something official stating they they are planning on doing the refurbishment in FL-even if it's in the same two HIF buildings they've got or if they have to build or lease a separate refurbishment facility.The statement also implies that they think refurbishment will not be a complete tear down process that has to be handled at the CA factory. That is another huge question mark that's been hanging over the economics debates around reusability, and we now have some insight into answering it.
Quote from: sghill on 01/08/2015 03:09 pmQuote from: Jim on 01/08/2015 02:51 pmQuote from: Dudely on 01/08/2015 02:29 pmSo this means they already have a site planned where they will refurbish the stages! Does anyone know where exactly? That is the only reference to refurbishment in the doc.Why would it be any different than the places they are using now?Because until now, we couldn't answer whether or not they were going to truck each stage back to Hawthorne for a tear down and refurbishment. Now we can drive a stake in the ground because we've got something official stating they they are planning on doing the refurbishment in FL-even if it's in the same two HIF buildings they've got or if they have to build or lease a separate refurbishment facility.The statement also implies that they think refurbishment will not be a complete tear down process that has to be handled at the CA factory. That is another huge question mark that's been hanging over the economics debates around reusability, and we now have some insight into answering it.Question marks for who? Flight refurb shouldn't be much different than McGegor static fire refurb. Also, it still doesn't mean that first/early recovered stages*are not send back to McGregor (a likely place for returned stages returned Dragons went to there vs Hawthrone)*If they get enough stages from ASDS recoveries then they may bypass this for the shore landed stages.
I seem to recall you being vociferously in the "refurbishment-costs-may-make-reusability-unfeasible" camp when we were discussing all this last summer and now you're in the "it'll-be-ok" camp? The McGregor boosters never flew backwards at hypersonic speeds. We don't know what the returning stage is going to look like beyond the grainy video of that charred booster landing in the ocean the airplane took during the last landing.The point is that the booster may either need a complete tear down (and component replacements) requiring the abilities they have back at the CA factory- and I expect they will do this for the first few returns, or the booster may be good to go after an inspection, air in the tires, and fluid top-off, which allows them to use their existing HIF facilities, or get a new one (build or lease) for refurbishment in FL instead of CA. The EA for LC-13 indicates that SpaceX believes the latter is true- which is what Dudely pointed out in his post. I also pointed out that if the latter is indeed true, then we can also begin to put boundaries on questions about the economics of reusability because the refurbishment costs will likely be small.
Quote from: sghill on 01/08/2015 03:09 pmQuote from: Jim on 01/08/2015 02:51 pmQuote from: Dudely on 01/08/2015 02:29 pmSo this means they already have a site planned where they will refurbish the stages! Does anyone know where exactly? That is the only reference to refurbishment in the doc.Why would it be any different than the places they are using now?Because until now, we couldn't answer whether or not they were going to truck each stage back to Hawthorne for a tear down and refurbishment. Now we can drive a stake in the ground because we've got something official stating they they are planning on doing the refurbishment in FL-even if it's in the same two HIF buildings they've got or if they have to build or lease a separate refurbishment facility.The statement also implies that they think refurbishment will not be a complete tear down process that has to be handled at the CA factory. That is another huge question mark that's been hanging over the economics debates around reusability, and we now have some insight into answering it.Question marks for who? Flight refurb shouldn't be much different than McGegor static fire refurb.
So are we in agreement now, (especially taking into account Musk's comment at the AMA) that first stage refurb is a minimal task?
And just to be a pedant, the residual fuel is listed as being 15 gal LOX and up to 150 gal RP-1. 15 gal of LOX is not very much.