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Old 02-01-2018, 07:49 PM
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blackshire blackshire is offline
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Default Floating F9 first stage (links)

Hello All,

“A funny thing happened after the GovSat 1 launch on Wednesday” (see: http://spaceflightnow.com/2018/01/3...-status-center/ and http://spaceflightnow.com/2018/01/3...alcon-9-rocket/ ), and:

The Falcon 9’s first stage, which did not land on the drone ship but tested a very high thrust three-engine landing burn, survived its water landing, and Elon Musk has tweeted that they will try to tow it back to port. Here (see: http://spaceflightnow.com/2018/01/3...tellite-launch/ and http://finance.yahoo.com/news/space...-010302734.html ) are articles with photographs of the floating first stage, which is riding high in the water.
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Old 02-01-2018, 09:10 PM
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What is the high thrust landing for? The thing pretty much stops on a dime already.
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Old 02-01-2018, 09:37 PM
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Quote:
Originally Posted by tbzep
What is the high thrust landing for? The thing pretty much stops on a dime already.
They're being quiet about it--the audio call-outs of the first stage flight events can be heard in the GovSat 1 coverage (see: http://www.oldrocketforum.com/showthread.php?t=17092 ), and no on-board camera views from the first stage were shown. From what little is online about it, it looks like they tried a full-throttle, very brief, three-engine landing burn, and they didn't want to risk damaging the drone ship (it was on station nearby, because a call that it had acquired the rocket's signal was given during the ascent video coverage). Also:

My guess is using a very short three-engine landing burn might use less propellant than their current three-engine landing burn, which could allow them to successfully recover Falcon 9 first stages (and/or maybe Falcon Heavy side or core boosters?) after launching heavier payloads. (A few of their first stages essentially "landed on fumes" after lofting heavier geosynchronous satellites; on those launches, they played down the chances of successful landings because the very tight landing propellant reserves left no margin for error, wind-correction, or slight engine under-performance.) On one of those "Hail Mary" landings, it appeared that the first stage might have run dry, but just low enough that it barely stuck the drone ship landing successfully (that was the one where all--or nearly all--of the crush-able landing leg strut cushioning material was compacted).
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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
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