No one is pushing for Taurus II. It was Frank Culbertson playing to the crowd at a lunch lecture to a Florida space club near the Cape. I don't see this class of vehicle being able to lift an adequately sized capsule.
The Taurus II first stage is as capable as the Atlas V first stage
I keep hearing that people are pushing for using Taurus II as a potential launch vehicle for commercial crew. Can someone explain how using a Russian built first stage for Taurus II is acceptable while it is not acceptable to use an Atlas V because it has a Russian built engine for it's first stage? Or is this just Congressional logic, meaning it depends on who gives the biggest contributions.
Quote from: Downix on 07/24/2010 12:37 amThe Taurus II first stage is as capable as the Atlas V first stageT-II has roughly 3/4 of Atlas V liftoff thrust and Atlas is pretty much maxed out in terms of T/W so it is not as capable. That 3/4 in fact very roughly translates to their stated max LEO performance ratio.
Ukraine and Lybia are the only two countries that voluntarily gave up nuclear weapons.
Quote from: ugordan on 07/24/2010 01:59 amQuote from: Downix on 07/24/2010 12:37 amThe Taurus II first stage is as capable as the Atlas V first stageT-II has roughly 3/4 of Atlas V liftoff thrust and Atlas is pretty much maxed out in terms of T/W so it is not as capable. That 3/4 in fact very roughly translates to their stated max LEO performance ratio.No. Check again:Atlas V has 3.850 MN on takeoffTaurus II has 3.265 MN on takeoff.This means the Taurus II has 85% of the thrust of the Atlas V. Now, let us look at the weight:Atlas V first stage: 306,914 kg Taurus II first stage: 261,187 kgAnd as you can see, the first stage is also only 85% of the weight. So my original argument, a better upper stage could bring it to within the same range, fine for crewed operation.
Quote from: Downix on 07/26/2010 04:48 amQuote from: ugordan on 07/24/2010 01:59 amQuote from: Downix on 07/24/2010 12:37 amThe Taurus II first stage is as capable as the Atlas V first stageT-II has roughly 3/4 of Atlas V liftoff thrust and Atlas is pretty much maxed out in terms of T/W so it is not as capable. That 3/4 in fact very roughly translates to their stated max LEO performance ratio.No. Check again:Atlas V has 3.850 MN on takeoffTaurus II has 3.265 MN on takeoff.This means the Taurus II has 85% of the thrust of the Atlas V. Now, let us look at the weight:Atlas V first stage: 306,914 kg Taurus II first stage: 261,187 kgAnd as you can see, the first stage is also only 85% of the weight. So my original argument, a better upper stage could bring it to within the same range, fine for crewed operation.I would be interested to know where you got the Taurus 2 first stage mass and thrust. Both numbers seem high. Other published data gives 3.0199 MN sea level thrust. A 261 tonne first stage would be too heavy to lift with that thrust. Orbital's user guide says that the first stage burn will last for 235 seconds, but also says that max G-loading will be 6.0. That implies throttling, which means that propellant load can't be estimated by full mass rate times 235 seconds. I'm guessing that the first stage weighs something like 235 tonnes loaded. - Ed Kyle
The COTS documentation on NASAs website has the Taurus II weight, I even found it broken down per-stage and even per-load. 65000 kg of LOX, for instance.The thrust is also in Orbitals documentation. Aerojet found that the NK-33 was never pushed to its limits, and could actually support more thrust. The AJ26 can now throttle to 108%.
Quote from: Downix on 07/26/2010 04:08 pmThe COTS documentation on NASAs website has the Taurus II weight, I even found it broken down per-stage and even per-load. 65000 kg of LOX, for instance.The thrust is also in Orbitals documentation. Aerojet found that the NK-33 was never pushed to its limits, and could actually support more thrust. The AJ26 can now throttle to 108%.Super. Thanks! Use of RD-0124 as the second stage engine seems to point toward some first stage propellant offloading, unless the NK-33 thrust is increased even more than 108%. 114% (tested in the 1990s) would get Taurus 2e back up to full first stage propellant loading, and easily to the claimed 8.7 tonnes to LEO (perhaps 9 tonnes) from Cape Canaveral. - Ed Kyle
Quote from: edkyle99 on 07/27/2010 12:38 amUse of RD-0124 as the second stage engine seems to point toward some first stage propellant offloading, unless the NK-33 thrust is increased even more than 108%. 114% (tested in the 1990s) would get Taurus 2e back up to full first stage propellant loading, and easily to the claimed 8.7 tonnes to LEO (perhaps 9 tonnes) from Cape Canaveral. - Ed KyleYou are reading my mind. Pity Orbital or Aerojet are not hiring anything I'm qualified for...
Use of RD-0124 as the second stage engine seems to point toward some first stage propellant offloading, unless the NK-33 thrust is increased even more than 108%. 114% (tested in the 1990s) would get Taurus 2e back up to full first stage propellant loading, and easily to the claimed 8.7 tonnes to LEO (perhaps 9 tonnes) from Cape Canaveral. - Ed Kyle
Why buy Russian vehicles to put passengers on. We can just buy seats on Soyuz, at that point.
Two questions that you know that the politicians will ask:1) Can NK-33/AJ-26 be built in the US rather than the Ukraine? Even if it is still a foreign design, construction, testing and integration in the US will make a lot of people happier.
2) Is there a US upper stage alternative?IMHO at least, for (2), I think that the AJ-10 is an obvious answer.
For this application, the only reasonable U.S. option would have been RL-10, but that would have added the expense of hydrogen fuel infrastructure.