Athena III

[Salo]

Вариант для COTS от АТК и PlanetSpace.
http://www.floridatoday.com/apps/pbcs.dll/article?AID=/20080121/NEWS02/801210324

Alliant Techsystems today will divulge plans for a three-stage rocket based on NASA's shuttle and unmanned Athena and Taurus launch vehicles.

The shuttle's solid rocket boosters consist of four segments.

The planned first stage of the new booster would be equal to 21/2 of the shuttle's segments.

The second stage would be a Castor 120 solid rocket motor flown on Athena 1, Athena 2 and Taurus launch vehicles.

The third stage would be a Castor 30 rocket motor the company is developing.

It would be topped by a Lockheed Martin module that would guide cargo or crew carriers to the station.

The lineage of the unnamed rocket should give the PlanetSpace team an edge, Crook said.

The company plans to launch a small version of the rocket by 2009. A demonstration flight of the full-size vehicle is scheduled for late 2010.

[Salo]

http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=11539&start=1

FACT SHEET – Embargoed until Jan. 21, 2008
ATK Provides Launch Vehicle for the PlanetSpace COTS Solution

Mature propulsion systems provide near-term solution for COTS, as well as satellite and planetary markets

As part of the NASA COTS proposal, PlanetSpace and ATK have introduced an innovative launch vehicle based on propulsion with proven performance on multiple launch vehicles. The new launch vehicle provides a cost-effective, near-term capability for multiple space launch requirements including: COTS missions, LEO & GTO satellites, lunar payloads and planetary probes.

The first two stages are based on existing propulsion systems with long histories of performance.  Stage one is a 2.5 segment derivative of the Space Shuttle's 4-segment Solid Rocket Booster. The second stage is the ATK Castor 120, utilized on the Athena I, Athena II and Taurus launch vehicles.

That proven foundation is topped by an ATK Castor 30 third stage, and a flight proven Orbit Adjust Module (OAM).  ATK has been developing the Castor 30 internally for the last two years, and the OAM flew on both the Athena I and Athena II.

This innovative configuration of proven propulsion elements will be capable of providing low-cost launch services for the following missions:

         Mission               Payload Capability

•   International Space Station (ISS)            13,233 lbs./14,795 lbs
•   Geosynchronous Transfer Orbit (GTO)           6,160 lbs.
•   Trans-Lunar Insertion (TLI)                 4,147 lbs.
•   Mars Science Mission                2,992 lbs.

The performance capability for the initial vehicle is nearly 25 percent greater than the heavy version of a Delta II for GTO missions, and almost 40 percent better for TLI missions.  In addition, an upgraded vehicle would provide an additional 1,560 lbs. of payload capability for ISS missions by incorporating composite case and solid propellant upgrades. Using proven propulsion elements, the new launch vehicle can achieve first flight by late 2010 from Cape Canaveral Air Force Station.

About ATK

ATK has the world's largest portfolio of solid rocket motors.  We are combining our leadership in solid propellant technologies with our system engineering and integration capabilities to provide future launch systems in commercial, military, and space exploration markets.

[Salo]

Там же:

SRB
Stage 1 Total: 366 tonnes
Stage 1 Propellant: 311.79 tonnes
Stage 1 Avg ISP: 259.4 sec

Castor 120
Stage 2 Total: 53 tonnes
Stage 2 Propellant: 48.95 tonnes
Stage 2 ISP: 286 sec

Castor 30
Stage 3 Total: 18.55 tonnes
Stage 3 Propellant: 17.13 tonnes
Stage 3 ISP: 293 sec

Lockheed OAM
Stage 4 Total: 0.714 tonnes
Stage 4 Propellant: 0.36 tonnes
Stage 4 ISP: 222 sec

- Ed Kyle

[Salo]

Там же:

aero313 - 21/1/2008 11:30 AM

As for the vehicle, can you say "resonant burn"? There was an article in Sunday's Washington Post that talked about the resonant burn problems with Ares I. This vehicle will have the same problem. The Castor 120 has a 50 hz resonance. I assume the 2.5 segment first stage will have about a 30-35 hz resonance.

[Salo]

BTW, my launch weight guesses for the three interesting COTS launch vehicles are: 255 tonnes for Taurus II, 336 tonnes for Falcon 9, and 440 tonnes for Athena III. Liftoff weight to 185 x 51.6 deg payload weight ratios are 50, 35, and 73, respectively.

It is hard to remember a more interesting launch vehicle competition in U.S. history. Here are three different approaches to the problem that not only produce three differing technological solutions but also three different payload capability solutions. We have all solid versus all liquid versus a solid/liquid combination. We have monster solid booster versus twin engine liquid versus mega-cluster liquid. We have two stage versus three stage versus four stage. And so on.

The EELV compete was nearly as interesting, but lacked the immediate drama of the current race. The CELV competition wasn't nearly as fascinating, mainly because what became Titan 4 was all but a foregone conclusion.

- Ed Kyle

Edited by edkyle99 4/2/2008 12:18 AM

Taurus II's payload ratio is comparable to Delta II, another liquid/solid mix. Falcon 9 approaches, but doesn't quite reach, the Atlas IIA/III realm, consistent with an all-liquid launch vehicle. There really isn't a good comparison for all-solid "Athena III". Lockheed's old Athena II, a much smaller vehicle (1/4th the liftoff mass) that used composite motor cases, would have had a similar gross launch weight to payload ratio, but a smaller dry mass to payload ratio.

The gross weight comparison is striking. Athena III is going to weigh 440 tonnes by my figuring (nearly 1 million pounds) at liftoff - more than either base EELV model and nearly as much as a Zenit 2, a rocket that hauls more than two times as much payload. Athena III's dry mass would be about three times that of Taurus II and roughly 2.8 times more than Falcon 9, but it would only carry 1.18 times more payload than Taurus II and 1.5-ish times LESS payload than Falcon 9.

This may or may not provide a clue about the solid versus liquid cost question. Presumably, Athena III cannot cost more than 1.17 times as much as Taurus II despite weighing more than 1.7 times as much at liftoff and 3 times as much dry. The Falcon 9 comparison is another thing altogether.

- Ed Kyle