Quote from: Prober on 12/18/2015 12:01 pmQuote from: rpapo on 12/18/2015 10:24 amTexas: Add dust.Florida: Add salt.don't forget the effects of Solar radiation ie sunshineIt's more than just ambient environmental conditions. I know it's a totally different vehicle, but think back to the issues around the GUCP. http://www.nasaspaceflight.com/tag/gucp/Could some of the problems be with the umbilical attachments to the vehicle at the launch site that are different than Texas? For a static fire in McGregor, you can bolt the fill lines directly to the stage while in Florida these lines have to be some sort of quick disconnect that detaches at launch. The cooled LOX is above the melting point of nitrogen (it's actually right near the boiling point of nitrogen, so maybe they're using LN2 to cool it), so I don't think they're seeing solidification of air around the very cold parts like the GUCP, but if there is water condensing then freezing around areas where it didn't freeze before, you could run into problems keeping a good seal or maintaining electrical conductivity of the umbilicals - you might not see that in McGregor if the lines were bolted.
Quote from: rpapo on 12/18/2015 10:24 amTexas: Add dust.Florida: Add salt.don't forget the effects of Solar radiation ie sunshine
Texas: Add dust.Florida: Add salt.
Quote from: Mike_1179 on 12/18/2015 12:31 pmQuote from: Prober on 12/18/2015 12:01 pmQuote from: rpapo on 12/18/2015 10:24 amTexas: Add dust.Florida: Add salt.don't forget the effects of Solar radiation ie sunshineIt's more than just ambient environmental conditions. I know it's a totally different vehicle, but think back to the issues around the GUCP. http://www.nasaspaceflight.com/tag/gucp/Could some of the problems be with the umbilical attachments to the vehicle at the launch site that are different than Texas? For a static fire in McGregor, you can bolt the fill lines directly to the stage while in Florida these lines have to be some sort of quick disconnect that detaches at launch. The cooled LOX is above the melting point of nitrogen (it's actually right near the boiling point of nitrogen, so maybe they're using LN2 to cool it), so I don't think they're seeing solidification of air around the very cold parts like the GUCP, but if there is water condensing then freezing around areas where it didn't freeze before, you could run into problems keeping a good seal or maintaining electrical conductivity of the umbilicals - you might not see that in McGregor if the lines were bolted.Oh the GUCP! That brings back "fun" memories!
Weather detoriated significantly today - we have an upcoming cold front. It rains hard at this moment.
I did not see this tweet posted here..Quote@elonmusk Did you guys get #Falcon9 O2 down to -340F on the test stand at #McGregor? Is this just an integration issue at LC40? Elon Musk @elonmusk 6h6 hours ago@craigcocca It worked in TexasSo.. it should not be a vehicle, but a stand issue?
@elonmusk Did you guys get #Falcon9 O2 down to -340F on the test stand at #McGregor? Is this just an integration issue at LC40? Elon Musk @elonmusk 6h6 hours ago@craigcocca It worked in Texas
Quote from: FutureSpaceTourist on 12/18/2015 08:44 amQuote from: ngilmore on 12/18/2015 12:39 amhttps://twitter.com/elonmusk/status/677663227271118848QuoteElon Musk @elonmusk 1m1 minute ago@PaigeANjax -340 F in this case. Deep cryo increases density and amplifies rocket performance. First time anyone has gone this low for O2.Here's an interesting response to Elon's tweets:https://twitter.com/george_sowers/status/677724984165330944QuoteGeorge Sowers @george_sowers 4h4 hours ago.@elonmusk Thats why we don't bother. Lots of complexity for little gain. https://twitter.com/george_sowers/status/677730399242457089QuoteGeorge Sowers @george_sowers 4h4 hours ago.@rocketrepreneur @elonmusk Tough to know the conditions of LOX at liftoff.I guess Spacex could say the same about LH2. It is just a matter of figuring the ROI. LH2 requires more insulation everywhere and haz gas detection, subcooled LOX requires active cooling.
Quote from: ngilmore on 12/18/2015 12:39 amhttps://twitter.com/elonmusk/status/677663227271118848QuoteElon Musk @elonmusk 1m1 minute ago@PaigeANjax -340 F in this case. Deep cryo increases density and amplifies rocket performance. First time anyone has gone this low for O2.Here's an interesting response to Elon's tweets:https://twitter.com/george_sowers/status/677724984165330944QuoteGeorge Sowers @george_sowers 4h4 hours ago.@elonmusk Thats why we don't bother. Lots of complexity for little gain. https://twitter.com/george_sowers/status/677730399242457089QuoteGeorge Sowers @george_sowers 4h4 hours ago.@rocketrepreneur @elonmusk Tough to know the conditions of LOX at liftoff.
https://twitter.com/elonmusk/status/677663227271118848QuoteElon Musk @elonmusk 1m1 minute ago@PaigeANjax -340 F in this case. Deep cryo increases density and amplifies rocket performance. First time anyone has gone this low for O2.
Elon Musk @elonmusk 1m1 minute ago@PaigeANjax -340 F in this case. Deep cryo increases density and amplifies rocket performance. First time anyone has gone this low for O2.
George Sowers @george_sowers 4h4 hours ago.@elonmusk Thats why we don't bother. Lots of complexity for little gain.
George Sowers @george_sowers 4h4 hours ago.@rocketrepreneur @elonmusk Tough to know the conditions of LOX at liftoff.
Can they do the test fire even when the Weather is red for launch? Certainly don't want the wind blowing the rocket around on take off. If the rocket it still held down what weather concerns would there be aside from maybe lighting?
Quote from: ngilmore on 12/18/2015 12:39 amhttps://twitter.com/elonmusk/status/677663227271118848QuoteElon Musk @elonmusk 1m1 minute ago@PaigeANjax -340 F in this case. Deep cryo increases density and amplifies rocket performance. First time anyone has gone this low for O2.Here's an interesting response to Elon's tweets:https://twitter.com/george_sowers/status/677724984165330944QuoteGeorge Sowers @george_sowers 4h4 hours ago.@elonmusk Thats why we don't bother. Lots of complexity for little gain.
Quote from: Jim on 12/18/2015 11:49 amI guess Spacex could say the same about LH2. It is just a matter of figuring the ROI. LH2 requires more insulation everywhere and haz gas detection, subcooled LOX requires active cooling.I'd venture that the use of LH2 (over RP1) is a whole lot more gain than the subcooling/densification that SpaceX is pursuing. And most of the extra effort required to handle LH2 has been known for decades - but we still "learn" some interesting things every so often (stuff we should have known).
I guess Spacex could say the same about LH2. It is just a matter of figuring the ROI. LH2 requires more insulation everywhere and haz gas detection, subcooled LOX requires active cooling.
It could be either. Or both.
And please, let's not start the LH2 vs LOX thing. Both have advantages and drawbacks.
Quote from: abaddon on 12/18/2015 03:13 pmAnd please, let's not start the LH2 vs LOX thing. Both have advantages and drawbacks.At risk of bringing this up again, is there a temperature between -340F (F9 LOX) and -434F (hydrogen) where handling of liquids goes from relatively easy to relatively challenging?
Quote from: RedLineTrain on 12/18/2015 03:40 pmQuote from: abaddon on 12/18/2015 03:13 pmAnd please, let's not start the LH2 vs LOX thing. Both have advantages and drawbacks.At risk of bringing this up again, is there a temperature between -340F (F9 LOX) and -434F (hydrogen) where handling of liquids goes from relatively easy to relatively challenging?And the fact that Hydrogen atoms are small. It's the same thing that makes handling Helium challenging.