After considering some reasonable Athena 3 concepts, I've played with a few high energy upper stage ideas. These aren't meant to be "real" (the Lego (TM) thing), but give an idea of payloads for various propellant combinations. Obviously they cross deep into Atlas 5 territory, which Lockheed would not do unless it had a very good reason. (And yes, Jim, I should draw a big fairing around these Centaurs, because they can't support the payload otherwise.) The last concept is Liberty-esque, but assumes a composite case booster, etc, so is presented just to show a max-payload range.I've found that a bigger-than Castor 120 second stage would improve performance. Something about 1.5 times heavier would work. ATK has been burning Castor 120-diameter motors for the Air Force, but I'm not sure that anything longer than Castor 120 itself has been tested or considered. - Ed Kyle
First, the Antares launch pad at Wallops has been a long time coming and must have cost someone a pretty penny. An Athena 3 pad might be more straightforward.
Second, both Orbital and Lockheed Martin manufacture traditional satellites. SpaceX does not.
Third, SpaceX is talking about three launch complexes, creating more infrastructure than either Orbital or Lockheed-Athena. Either they are going to perform three times as many launches as Antares or Athena, or their fixed costs are going to be higher.
Fourth, Athena 3 would expose payloads to the highest g-forces of the three (I think).
Quote from: notsorandom on 04/16/2012 12:40 pmEd, the hypothetical 3 composite segment 110t LH2 Athena-X, the performance of that configuration is better then Liberty or Ares I. Is the performance of the composite solid what makes the difference there? In other words is a three segment composite that much better then a five segment steel case solid?According to my guesstimate the much improved propellant mass fraction of the first stage makes the difference. But, of course, the real implementation would be unlikely to match my guesses. No matter the details, composite case can provide substantial improvement. Look at the Castor and Orion motors for examples. - Ed Kyle
Ed, the hypothetical 3 composite segment 110t LH2 Athena-X, the performance of that configuration is better then Liberty or Ares I. Is the performance of the composite solid what makes the difference there? In other words is a three segment composite that much better then a five segment steel case solid?
Quote from: Ronsmytheiii on 05/10/2012 01:07 amBump for its larger sibling Linerty news.I'm not yet sure they're directly related. Liberty is ATK/EADS. Athena, including Athena 3 if it is ever developed, is Lockheed Martin. Of course ATK would pour motors for both rockets. - Ed Kyle
Bump for its larger sibling Linerty news.
Athena II as the upper stage. Hmmm. Actually stacking two Castor 120s and a Castor 30 on top of "another ATK solid rocket motor" could lift more than 5.9 tonnes to LEO from Florida. A lot more. I figure better than 10 tonnes. - Ed Kyle
This is interesting.http://www.lockheedmartin.com/us/news/press-releases/2012/april/0417-ss-cls.htmlAthena II as the upper stage. Hmmm. Actually stacking two Castor 120s and a Castor 30 on top of "another ATK solid rocket motor" could lift more than 5.9 tonnes to LEO from Florida. A lot more. I figure better than 10 tonnes. - Ed Kyle
How many segments are you assuming in your calcs, Ed? That might be the difference.
This is interesting.http://www.lockheedmartin.com/us/news/press-releases/2012/april/0417-ss-cls.html"The company recently selected KLC as its dedicated West Coast launch facility as it looks to expand launch capability with Athena III for commercial and government customers. Utilizing the Athena I and II as the upper stages and another ATK solid rocket motor as the first stage, Athena III will be capable of launching satellites weighing 4,600 kg (10,150 lbs.) from Alaska and 5,900 kg (13, 000 lbs.) from the Florida space coast."Athena II as the upper stage. Hmmm. Actually stacking two Castor 120s and a Castor 30 on top of "another ATK solid rocket motor" could lift more than 5.9 tonnes to LEO from Florida. A lot more. I figure better than 10 tonnes. - Ed Kyle