Thread: Antares Launch
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Old 04-17-2019, 08:52 PM
frognbuff frognbuff is offline
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Location: Colorado Springs, CO
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Quote:
Originally Posted by tbzep
Just looking at info for today's Antares launch.
As a short background, Orbital ATK's Antares 1st stage is from the Russian company that makes the Zenit, and it uses a pair of Energomash designed RD-181's.
2nd stage is a solid Castor 30 series, IIRC.

That's where it's interesting. Falcon 9 has a quick staging process, as did the Saturns, etc. The Antares has a 43 second coast phase where it will drop interstages, fairings, etc. before the Castor lights. That reminds me of a lot of sounding rocket flight profiles.

I wonder if it has anything to do with the hot rod RD-181's. They are way more than the Antares needs and have been used at a partial throttle setting to keep from over stressing the airframe. Was the flight profile the same with the old AJ26 (Russian NK-33)?


Orbital/Orbital-ATK/NGIS uses the coast period for trajectory shaping on their all-solid propellant vehicles. See, for example, the Pegasus flight profile info here: https://infogalactic.com/info/Pegasus_(rocket)

So, I'm guessing this has more to do with the solid-propellant second-stage on Antares than anything to do with the throttleable RD-181s. All-liquid vehicles do their trajectory shaping via longer burns and/or multiple burns, which solids don't offer.

Hopefully Matt Steele will weigh in and set us all straight!
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