Sid454 - 24/1/2008 12:14 AMThe real issue is can production be ramped up before the 50 remaining NK-33s are used up?
TrueGrit - 25/1/2008 4:54 PMQuestion would be... What would Taurus II with a Delta II upperstage instead of the Castor be capable of?
Sid454 - 25/1/2008 8:47 PM1. I'd go with a centaur resized for use on the Taurus II that or have spacedev make a hybrid stage if they don't get selected for COTS this would offer more flexibility then the castor allow you to launch live cargo ie people and should have a little higher ISP or the second stage RCS would then be a gimme since it can just use some of the cold N2O gas thats already under pressure.2. Every company likely has a plan B if they can't be a prime contractor they can still e a sub contractor o a winner.3. A related story can Taurus II scale up enough to lift something like dream chaser or even something lighter like the t/space CXV?Though orbital likely has their own solution maybe based off the X34.4. If Rocket dyne really does follow though and shut down the SSME production line those people will be available for aerojet to hire.5. A real irony is the USA may be a better bet then the former soviet union for producing these engines because of the recent experience with the SSME.
TrueGrit - 25/1/2008 3:54 PMQuestion would be... What would Taurus II with a Delta II upperstage instead of the Castor be capable of?
TrueGrit - 26/1/2008 4:08 PM How much less impulse does the Taurus II first stage have in comparision to the Delta II combined first stage and SRMs? It would have to be quite significant...
Actually, the Taurus II first stage has more impulse than both Delta II's first stage/SRM combinations. Here 's the comparison (all numbers vacuum):
A single GEM-40: Thrust: 50.2 t, Burn time: 64 sec, total impulse: 3213 t-sec
Delta II core: Thrust: 107.5 t, Burn time: 265 sec, total impulse: 28487 t-sec
Taurus II: Thrust: 387.8 t, Burn time: 171 sec (approx., assumes 200 t of propellant)
Therefore,
Delta II 73XX core + 3 SRB's total impulse: 38127 t-sec
Delta II 79XX core + 9 SRB's total impulse: 57408 t-sec
Taurus II Stage 1 total impulse: 66313 t-sec
Delta benefits from the additional staging event (two additional events for the 79XX) and the smaller thus lighter fairing. The larger core diameter makes the AJ-10's long nozzle airframe structural penalty (interstage mass) larger on T-II than on D-II, thus favoring the Castor-30. On the other hand, D-II (esp. the 79XX) is a bit draggier than T-II.
T-II with the Castor-30 and ORK is "bottom heavy", as typically LV's are at the beginning of their life cycle. As more performance is required of them, they get bigger and bigger upper stages, and more and more SRB's. Who knows, T-II thirty years from now may look just like a Delta 79XX on steroids!
Delta is an amazing rocket, more so when considering its evolution. Unfortunately, it is at the end of its product cycle life, its components have become (they weren't!) very expensive to manufacture, and requires a complex and expensive to maintain vertical assembly/launch pad complex.
The Delta II core costs about as much in parts and assembly/test labor as the Taurus II stage 1 (well, at least I hope that's how it ends up), yet is provides less than half the impulse. And the price of GEM-40's and other SRB's seems to increase each day we ask.
TrueGrit - 26/1/2008 4:08 PMWonder how much larger the Delta II stage would have to grow to make it equivelent?
edkyle99 - 26/1/2008 1:01 AM QuoteTrueGrit - 25/1/2008 3:54 PM Question would be... What would Taurus II with a Delta II upperstage instead of the Castor be capable of? Less. Quite a bit less. By my figuring, you would loose about one metric ton of LEO payload capability using the Delta II second stage rather than the Castor 30 second stage. - Ed Kyle
TrueGrit - 25/1/2008 3:54 PM Question would be... What would Taurus II with a Delta II upperstage instead of the Castor be capable of?
TrueGrit - 26/1/2008 4:08 PM That much lost is a little surprising?
Here's a very rough Excel-and-Solver calculation (all figures approximate, but the relative difference is roughly correct):
T-II S1 C-30 S2 T-II S1 D-II S2Payload 20521 5621 11823 4873 KgJettison 16400 1400 16400 950 KgFinal 36921 7021 28223 5823 KgPropellant 200000 13500 200000 6000 KgInitial 236921 20521 228223 11823 Kg
Isp (Vac) 331 282 331 319 sDV (Ideal) 6034 2966 6785 2215 m/s
Total DVI Actual Target Actual Target 9000 9000 9000 9000 m/s
As can be seen, a T-II S1/C-30 combination has about 800 Kg more payload to a 9 Km/s Ideal DV trajectory than a T-II/Delta II S2 combination. Actually, the difference is closer to edkyle99's 1 ton number due to the higher structural penalty associated with the long AJ-10 nozzle on the larger (3.9m vs. 2.44m) T-II core diameter.
(could somebody teach me how to either enter a table properly or place a figure in the middle of a text without having to store it on some public URL?... I can design rockets, but I can't format squat on this forum...)
(also, can somebody tell me how to use greek letters on the signature line? I'm getting sick and tired of my pig-greek phonetic spelling)
(triple *sigh*) thanks, marsavian. I knew about the "preformatted text" tag, but somehow, after carefully entering the preformatted text between <pre> and <pre>, I preview the text (pun intended) and someting kills my tags and enters a large number of extraneous and random tags... and reverts the font to proportional... arghhhh!Also, the Rich Text Editor and gree font options don't appear to be available when entering one's signature line...