One of the objectives for the long-duration Booster static fire they did a month or two ago was testing autogenous pressurization. It may be that they use autogenous in flight, but pressurize with helium on the ground before launch. That would simplify the GSE needs for this initial test by avoiding the need to supply high-pressure gaseous CH4 and O2. Probably something they would like to eliminate long-term.
Quote from: lrk on 04/18/2023 03:53 pmOne of the objectives for the long-duration Booster static fire they did a month or two ago was testing autogenous pressurization. It may be that they use autogenous in flight, but pressurize with helium on the ground before launch. That would simplify the GSE needs for this initial test by avoiding the need to supply high-pressure gaseous CH4 and O2. Probably something they would like to eliminate long-term.It will be difficult to eliminate He pressurization on the upper stage during boost, because the subcooled props will really tend to condense out the gaseous autogenous pressurants, especially when agitated during flight.They could get around that issue by using the booster to supply hot gaseous pressurants to the upper stage in flight, or by running a heater or APU on the upper stage.
Quote from: envy887 on 04/18/2023 04:01 pmQuote from: lrk on 04/18/2023 03:53 pmOne of the objectives for the long-duration Booster static fire they did a month or two ago was testing autogenous pressurization. It may be that they use autogenous in flight, but pressurize with helium on the ground before launch. That would simplify the GSE needs for this initial test by avoiding the need to supply high-pressure gaseous CH4 and O2. Probably something they would like to eliminate long-term.It will be difficult to eliminate He pressurization on the upper stage during boost, because the subcooled props will really tend to condense out the gaseous autogenous pressurants, especially when agitated during flight.They could get around that issue by using the booster to supply hot gaseous pressurants to the upper stage in flight, or by running a heater or APU on the upper stage.Great point. We know that there is no connection (not even eletrical, only a wireless data one, IIRC) between the two stages, so this might be true. But wasn't the problem on the booster?
they rely on National Weather Service entirely.
...But wasn't the problem on the booster?
Quote from: cuddihy on 04/18/2023 02:20 pm they rely on National Weather Service entirely. That's a new one for me - that would be highly unethical for the NWS to be their sole weather provider, plus that would mean their weather criteria are available for public viewing and we know that's not the case Where have you seen that publicized?
Prior to launch, SpaceX will deploy weather balloons to measure weather data. ...
Weather and ocean current data would be used to further characterize the debris field as the operation is conducted. During the operation, SpaceX would coordinate findings and action items directly with the USCG Sector 14 to ensure all of the requirements of the Letter of Intent are met.
Given that the propellant liquids are super chilled, using GOX or GCH4 in the ullage space would cause much of the gas to condense into liquid. He won't condense at these temps, so it is used to keep the pressure stable initially. Once the engines start, the autogenous system takes over.He may also be used for purging lines, though N2 is probably sufficient for most instances.I'm not sure; is He used to initially spin any of the Raptor 2 turbopumps too?Ross.
I don't think there is a 37th Space Wing? They have their own meteorologists.
That is for winds aloft and not local conditions.
SpaceX plans to use a portable sound detection and ranging (SODAR) device to collect weather data needed for launch and landing. The SODAR sends out a short sonic pulse every 15 minutes that can reach 92 decibels (dB) at the source and dissipates to 60 dB within 100 feet. The SODAR would be located on a SpaceX private parcel in the production and manufacturing area, north of the solar farm.