I don't expect the Falcon 9 to have a reusable upper stage, just because the - with a kerosene-based system, the specific impulse isn't really high enough to do that, and a lot of the missions we do for commercial satellite deployment are geostationary missions. So, we're really going very far out. These are high delta-velocity missions, so to try to get something back from that is really difficult. But, with the next generation of vehicles...
50 F9 or 15ish FH launches a year may be reason to revisit the decision not to do the engineering for second stage reuse
A reusable second stage that returns the fairing and dispenser would make lots of sense when there are so many identical launches. The fairing could open on one side as done on STS, or hinge back fully and then re-close. Expendible fairings, dispensers, second stages launched week after week will be prohibitively expensive -- and the fuel to de-orbit all of this hardware (with the exception of the fairing as currently used) will need to be in the mass budget anyway.Note: This same argument could be made for a reusable tanker second stage...
First get the F9 1st stage back and reuseSecond launch and get back ( land-landed ) and reuse Dragon ( with super Draco )Learn from them.Then make a reusable 2nd stage.If it could have enough performance for Dragon cargo/crew/lab and or enough performance for some LEO payloads. ( More for a single payload )( Just needs to lower cost enough to increase profit a little. )And that would be a prototype for a more cost effective next generation two stage RLV.Could also be used to test return for reuse from GTO on FH for next generation two stage RLV.Could give them some data for their possible future MCT.I don't see it being made just for the F9/FH. Their are new methods of manufacturing that are lowering production cost that the 2nd stage can be cheap enough to just make a new one.
1) What would justify reconsideration of the expendible second F9 stage 'decision'?2) What technology would be needed to enable cost-effective reuse?
I believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse.
Quote from: nadreck on 01/21/2015 08:49 pmI believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse. This is the crux of the issue... how low can these costs be driven. If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements. ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.
Third requirement is there are not other better things that the SpaceX engineers can be working on. That is the opportunity cost.
First requirement is that it is economically justified. Development cost < savings in launch costs. For a 3 year payback, 50 launches /year and $10M savings / launch that seems perfectly possible.
Quote from: AncientU on 01/21/2015 09:12 pmQuote from: nadreck on 01/21/2015 08:49 pmI believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse. This is the crux of the issue... how low can these costs be driven. If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements. ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.If SpaceX uses the Moog EELV secondary payload adapter (ESPA) rings to mount Elonsats of less than 182 kg each. Then in theory you could stack 12 rings to lift 72 Elonsats per flight in the standard SpaceX PLF. Mass of the Elonsats and ESPA rings is about 15 tonnes.So in theory a total of 56 flights will complete the Elonsat constellation at a tempo of about 10 flights annually, also the number of annual Elonsat replacement flights after constellation deployment.So the number of flights annually to send up Elonsats will be too low to justified development of a reusable 2nd stage.Presuming the eventual Elonsat will be similar in size and mass to the Orbcomm-2 sats.
Quote from: Zed_Noir on 01/22/2015 01:38 amQuote from: AncientU on 01/21/2015 09:12 pmQuote from: nadreck on 01/21/2015 08:49 pmI believe I could make a good business case for working on bringing the costs of the 2nd stage, faring and satellite support hardware that would be lost, down over spending the same capital on F9 2nd stage reuse. This is the crux of the issue... how low can these costs be driven. If SpaceX is flying 20 ElonSats per trip, this requires 200 second stages/fairing pairs/dispensers (100 if double the number can be launched each time) to get the constellation established without considering replacements. ISTM that the cost of 200 M1D vacs alone would possibly fund the development effort.If SpaceX uses the Moog EELV secondary payload adapter (ESPA) rings to mount Elonsats of less than 182 kg each. Then in theory you could stack 12 rings to lift 72 Elonsats per flight in the standard SpaceX PLF. Mass of the Elonsats and ESPA rings is about 15 tonnes.So in theory a total of 56 flights will complete the Elonsat constellation at a tempo of about 10 flights annually, also the number of annual Elonsat replacement flights after constellation deployment.So the number of flights annually to send up Elonsats will be too low to justified development of a reusable 2nd stage.Presuming the eventual Elonsat will be similar in size and mass to the Orbcomm-2 sats.Math of this is eluding me.. 72 Sats per launch.. 720 satellite constellation = How many total flights?