Would the Texas launch site have better or worse performance than Florida?There is a performance gain since the site is further south. The boost from the Earth's rotation is 416 m/s at the 26o of Brownsville, compared to the 409 m/s of Cape Canaveral at 28.5o. So a gain of 9 m/sThere is a performance loss since a dogleg, or an non-direct-East launch azimuth is needed. For simplicity, assume the booster heads straight east, then the second stage heads off at different angle. Since the F9 stages at about 2500 m/s, we can find the angle that loses 9 m/s as cos-1((2500-9)/2500) = 4.86o. Looking at the maps above, 5o is a pretty sharp turn, plus more optimized trajectories are possible. So likely the losses from the dogleg are less than 9 m/s, and Texas will be slightly better.Finally, most of the satellites from Texas will be heading to GTO. To go from a 300 x 300 parking orbit to GTO, with no inclination change at injection, takes about 2430 m/s. From Texas, this leaves the satellite with a GEO apogee and 26o inclination, with about 1770 m/s to GEO. To get this from Florida, you need to either remove some inclination with the injection burn, or go a super-synchronous orbit. Either case requires at least 20 m/s more from the booster. Not a big difference, but the advantage goes to Texas.So overall, despite the dogleg, Texas should be slightly better to GTO than the Cape.
In September 2014, subsequent to the bulk of this thread, Dan Adamo released a paper and was interviewed on The Space Show (link) where he expressed a great deal of skepticism about safe trajectories from Brownsville.It is interesting to see the Air Force's recent calculations and receptiveness to Cuban overflight that is supported by the 2017 introduction of AFTS by SpaceX. See Florida Today article.
I was talking about Mexican Penisula, which is only 500 miles down range, and is just a few degrees offline from the SE path to the Caribbean. They need to sneak between the Yucatan and Cuba, right ? And it should be WEST Africa, for the directionally challenged. I doubt debris crossed the entire continent of Africa from an east coast launch.
I wouldn't mind if some enterprising mod wanted to move a load of posts from the Texas thread to here.
Quote from: LouScheffer on 01/16/2018 02:47 pmWould the Texas launch site have better or worse performance than Florida?There is a performance gain since the site is further south. The boost from the Earth's rotation is 416 m/s at the 26o of Brownsville, compared to the 409 m/s of Cape Canaveral at 28.5o. So a gain of 9 m/sThere is a performance loss since a dogleg, or an non-direct-East launch azimuth is needed. For simplicity, assume the booster heads straight east, then the second stage heads off at different angle. Since the F9 stages at about 2500 m/s, we can find the angle that loses 9 m/s as cos-1((2500-9)/2500) = 4.86o. Looking at the maps above, 5o is a pretty sharp turn, plus more optimized trajectories are possible. So likely the losses from the dogleg are less than 9 m/s, and Texas will be slightly better.Finally, most of the satellites from Texas will be heading to GTO. To go from a 300 x 300 parking orbit to GTO, with no inclination change at injection, takes about 2430 m/s. From Texas, this leaves the satellite with a GEO apogee and 26o inclination, with about 1770 m/s to GEO. To get this from Florida, you need to either remove some inclination with the injection burn, or go a super-synchronous orbit. Either case requires at least 20 m/s more from the booster. Not a big difference, but the advantage goes to Texas.So overall, despite the dogleg, Texas should be slightly better to GTO than the Cape.Assuming the 5.5mT to GTO that SpaceX lists on their capabilities page is the limit for ASDS recovery of GTO launches. How much of a mass increase does launching out of Boca Chica (vs. KSC/CCAFS) gain them, for launches to equivalent orbits? I can't imagine it's very much given the small delta-v differences you've calculated. Probably not within the significant digits.
Quote from: philw1776 on 01/15/2018 06:29 pmQuote from: stcks on 01/15/2018 06:14 pmQuote from: Nomadd on 01/15/2018 05:57 pmMaybe Envy887 or somebody else smarter than me could say how far downrange an expended 1st stage or a second stage that fails to fire might come down. That's probably a big factor in how far downrange a populated area has to be.Well I'll reply even though I'm dumber than both you and envy887. According to the FCC filings and Raul's nice map, recoverable GTO first stages can hit about 420 miles downrange. Fairings can go 560 miles downrange.550 miles to Yucatan Over 800 miles to CubaWith the certified FTS why can't BC get the same OK they just got in Florida for high inclination launches?Depends on probability of failure while the IIP is over land and the population density of that land. A longer IIP dwell over high population areas means less likelihood of meeting the casualty requirements. Out of FL, the IIP only crosses ~80 miles of Cuba and later ~50 miles of Panama, which only takes seconds. Crossing Mexico and/or South America takes much longer and potentially crosses more population. They would have to run the numbers - it's possible this could be done, but it's a very different situation than launching south out of the Cape.
Quote from: stcks on 01/15/2018 06:14 pmQuote from: Nomadd on 01/15/2018 05:57 pmMaybe Envy887 or somebody else smarter than me could say how far downrange an expended 1st stage or a second stage that fails to fire might come down. That's probably a big factor in how far downrange a populated area has to be.Well I'll reply even though I'm dumber than both you and envy887. According to the FCC filings and Raul's nice map, recoverable GTO first stages can hit about 420 miles downrange. Fairings can go 560 miles downrange.550 miles to Yucatan Over 800 miles to CubaWith the certified FTS why can't BC get the same OK they just got in Florida for high inclination launches?
Quote from: Nomadd on 01/15/2018 05:57 pmMaybe Envy887 or somebody else smarter than me could say how far downrange an expended 1st stage or a second stage that fails to fire might come down. That's probably a big factor in how far downrange a populated area has to be.Well I'll reply even though I'm dumber than both you and envy887. According to the FCC filings and Raul's nice map, recoverable GTO first stages can hit about 420 miles downrange. Fairings can go 560 miles downrange.
Maybe Envy887 or somebody else smarter than me could say how far downrange an expended 1st stage or a second stage that fails to fire might come down. That's probably a big factor in how far downrange a populated area has to be.
Quote from: envy887 on 01/16/2018 04:48 pmQuote from: philw1776 on 01/15/2018 06:29 pmQuote from: stcks on 01/15/2018 06:14 pmQuote from: Nomadd on 01/15/2018 05:57 pmMaybe Envy887 or somebody else smarter than me could say how far downrange an expended 1st stage or a second stage that fails to fire might come down. That's probably a big factor in how far downrange a populated area has to be.Well I'll reply even though I'm dumber than both you and envy887. According to the FCC filings and Raul's nice map, recoverable GTO first stages can hit about 420 miles downrange. Fairings can go 560 miles downrange.550 miles to Yucatan Over 800 miles to CubaWith the certified FTS why can't BC get the same OK they just got in Florida for high inclination launches?Depends on probability of failure while the IIP is over land and the population density of that land. A longer IIP dwell over high population areas means less likelihood of meeting the casualty requirements. Out of FL, the IIP only crosses ~80 miles of Cuba and later ~50 miles of Panama, which only takes seconds. Crossing Mexico and/or South America takes much longer and potentially crosses more population. They would have to run the numbers - it's possible this could be done, but it's a very different situation than launching south out of the Cape.[reposting this Q from the Texas Launch Site thread (you're welcome, Nomadd)]Regarding 550 to Yucatan and 560 for fairings, specifically, but asking more generally: does SpaceX's work with fairing recovery have the opportunity to open up routes previously unavailable for overflight?How are the IIPs for each element calculated? Per the numbers cited above, it appears a SSE GTO trajectory would clear Mexico of any first stage impact risk. If the fairings could (reliably) be steered in a manner that reduced impact risks, would the the second stage then clear the peninsula (for some probability of 'clear')?Asking to better understand and learn here. Thanks.
After several successful launches, land overflight earlier in trajectory passes E-sub-c safety threshold. That said, Starship will also launch from Cape long-term.
This Embry-Riddle paper has been mentioned on NSF before but it deserves to be linked here as well.
Dogleg allows launches from BC to access the all important ~50 deg incl.(ISS, starlink).The other usefull inclinations will be:1. 23.5 for ecliptic plane launches. (moon, mars, etc)2. as close to 0 as possible. (geostationary)so when phobos is deployed what is the best compromise position to launch from to get to these inclinations with minimal dogleg?
Will a dogleg even by required for the 53-degree flights?
Quote from: RedLineTrain on 06/15/2021 04:17 pmWill a dogleg even by required for the 53-degree flights?Out of BC yes if you want to go just offshore of the yucatan.But that trajectory looks to be about 111deg. For 53 deg inclination you need 90+53=143deg azimuth.Which goes over the campeche at 988km. Is that allowed?
Note: Nearly all of the property that SpaceX purchased in Boca Chica was under the name "Dogleg Park LLC".Example shown in the images below.Maybe SpaceX is trying to tell us something...