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#140
by
edkyle99
on 06 Sep, 2010 14:45
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One of the very interesting things that the AEHF backup propulsion plan highlights, if it works, is the impressive propellant (and liftoff mass) reduction possible with use of Hall effect thrusters not just for station keeping, but for orbital maneuvering. If the plan had been to use Hall thrusters all along for much of the orbit change from GTO to GEO, it might have been possible to use a much smaller, cheaper rocket for the launch. Something like a straight EELV Medium, or even, if it were ready for a 2nd stage restart mission, a Falcon 9.
I wonder why this concept has yet to be adopted? The longer ascent to orbit and Time=Money?
- Ed Kyle
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#141
by
JosephB
on 07 Sep, 2010 01:07
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Good point. This is the first I've heard of HCT, which isn't all that surprising, but they sure seem to be an impressive bit of technology (especially if they can save the day.)
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#142
by
kevin-rf
on 07 Sep, 2010 16:00
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I wonder why this concept has yet to be adopted? The longer ascent to orbit and Time=Money?
What about more time spent in the Van Allen? You still need a "high" thrust engine to raise the perigee out of the upper atmosphere.
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#143
by
tonngo0
on 08 Sep, 2010 21:12
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#144
by
jcm
on 10 Sep, 2010 19:59
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It looks like the USAF are refusing to say who built the LAE. AvWeek says USAF wouldn't tell them; USAF (SMC) haven't replied to *my* email either, and Lockheed referred me to USAF. Nevertheless, I conclude that the manufacturer is probably IHI, from lack of other plausible candidates.
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#145
by
Skyrocket
on 10 Sep, 2010 21:22
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It looks like the USAF are refusing to say who built the LAE. AvWeek says USAF wouldn't tell them; USAF (SMC) haven't replied to *my* email either, and Lockheed referred me to USAF. Nevertheless, I conclude that the manufacturer is probably IHI, from lack of other plausible candidates.
The same from my research - i hope to get some info from IHI, but i have not received anything by now.
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#146
by
Targeteer
on 12 Sep, 2010 15:25
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Interesting although not terribly surprising I guess, that the manufacturer hasn't been/doesn't want to be identified. Success is always trumpeted while failure is not. Could the system be a previously unidentified one used only on classified systems and thus ID of the manufacturer is undesirable?
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#147
by
edkyle99
on 12 Sep, 2010 17:04
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It looks like the USAF are refusing to say who built the LAE. AvWeek says USAF wouldn't tell them; USAF (SMC) haven't replied to *my* email either, and Lockheed referred me to USAF. Nevertheless, I conclude that the manufacturer is probably IHI, from lack of other plausible candidates.
The same from my research - i hope to get some info from IHI, but i have not received anything by now.
If IHI doesn't jump to *deny* that it made the engine, we'll have our answer I think.
- Ed Kyle
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#148
by
marsavian
on 18 Oct, 2010 12:30
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http://www.spaceflightnow.com/atlas/av019/101017hct.htmlDespite the crisis that prompted the heroics to recover the satellite's mission, the Air Force remains confident the craft will achieve the correct orbit and have enough residual fuel for operations to fulfill its 14-year life to relay communications between the president, military commanders and troops on the battlefield.
"We have adequate hydrazine left over from the last burn to be able to do full operations, and all of our projections associated with the xenon that we have available for the Hall Current Thrusters (show) we will have adequate xenon available when we get on-orbit to also sustain a 14-year life or longer," Madden said.
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#149
by
kevin-rf
on 20 Oct, 2010 13:19
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#150
by
edkyle99
on 20 Oct, 2010 14:34
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New article:
http://www.spaceflightnow.com/atlas/av019/101019aehf2.html
AEHF-2 Delay'd to 2012
Confirms IHI engine
Indicates problem not with the IHI engine, but somewhere further back in the propulsion system.
Provides revised Atlas schedule.
What does that leave as potential culprits? Pressure regulators? Valves? Are tank heaters used?
- Ed Kyle
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#151
by
kevin-rf
on 20 Oct, 2010 23:05
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It did mention a potential work manship issue. Loose insulation blanket?
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#152
by
Antares
on 21 Oct, 2010 04:17
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Honestly, the way the various cultures work (both national and corporate) it could very well be the IHI engine, despite what is being said. There are many, many cases in this industry over the years of public spin opposite what really happened. Crucial is that those who know what really happened correct it for s/n #2. Allowing a guilty party to save face is one thing, being burned twice is another.
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#153
by
kevin-rf
on 15 Nov, 2010 17:50
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#154
by
kevin-rf
on 03 Feb, 2011 16:22
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#155
by
marsavian
on 10 Oct, 2011 12:31
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#156
by
sdsds
on 02 Nov, 2011 04:05
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AEHF-1 Satellite Arrives at Its Operational Orbit After 14-Month Journey
10/28/2011 - LOS ANGELES AIR FORCE BASE, Calif. -- The U.S. Air Force's first Advanced Extremely High Frequency military communications satellite completed a 14-month journey to reach its intended operational position in geosynchronous orbit, Oct. 24 [after] a sophisticated campaign of approximately 500 burnshttp://www.afspc.af.mil/news1/story.asp?id=123277770
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#157
by
HIPAR
on 12 Nov, 2011 15:53
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11/3/2011 - LOS ANGELES AIR FORCE BASE, El Segundo, Calif -- The U.S. Air Force's first Advanced Extremely High Frequency military communications satellite has completed initial activation of the protected communications payload and has begun on-orbit testing.http://www.losangeles.af.mil/news/story.asp?id=123278534A defective satellite .. a spectacular satellite rescue! My hat's off honoring those who worked the problem.
--- CHAS
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#158
by
The-Hammer
on 04 Jan, 2012 10:30
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Wired: Risky Rescue for Crippled Air Force SatelliteIt was an epic space rescue that, in audacity and risk, echoed NASA’s campaign to save the astronauts aboard the doomed Apollo 13 moon mission. The biggest difference between the 1970 Apollo operation and the 14-month recovery of AEHF-1, an Air Force communications satellite, is that money was the only thing immediately at stake in the latter.
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#159
by
kevin-rf
on 04 Jan, 2012 12:45
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