Quote from: kevin-rf on 04/01/2010 05:32 pmAntonioe, Every time you mention the Wallops soil I keep thinking about a mid 80's mag article that had a picture of a pile coming back up in a parking lot right next to the pile driver... Ooops!... I'd love to get my hands on that picture.As I may have mentioned early, in some cases they had to go down to 150 feet before they hit suitable load-bearing strata. The way they do it is they "splice" three 50-foot sections as they drive each section in. I've been told (but not seen it myself) that in these cases, the first 50 ft section could almost be driven down with your thumb...
Antonioe, Every time you mention the Wallops soil I keep thinking about a mid 80's mag article that had a picture of a pile coming back up in a parking lot right next to the pile driver...
The problem with that is not as much bigger tanks, but that you also double the burn time. Being ablatively cooled, the AJ-10 would have to be modified and re-certified (with appropriate testing) for the much extended burn time.
What's the latest word you can share on the enhanced 2nd stage? Based on this forum, it seems be the iPad of the spaceflight world, at least as far as speculation goes. --N
Would it have been possible to use two AJ-10's?
Just one teasing hint: logic always, in the end, prevails...
Hmm, the engine choice is logical. Vulcans are logical. Vulcan sounds like Vulcain...
That would be illogical. RL-10 is logical.
So. How much logic would NK-43/AJ-26-60 have?
As for using the NK-43 for the second stage, it's a very good engine with great ISP (346 s) and great T/W (120+). Unfortunately, it's about 5 times too big (about 400,000 lbf thrust vs. 80,000 lbf for the Castor 30). There are better Lox-kerosene engines for the Taurus II second stage from the thrust matching standpoint with equal or better Isp and good enough T/W (e.g. RD-0124 at 66,000 lbf thrust, Isp = 359 s, T/W = 63 with TVC and controller)
Quote from: William Barton on 04/02/2010 07:13 pmSo. How much logic would NK-43/AJ-26-60 have?Antonio mentioned this a while back:Quote from: antonioe on 03/19/2010 03:55 pmAs for using the NK-43 for the second stage, it's a very good engine with great ISP (346 s) and great T/W (120+). Unfortunately, it's about 5 times too big (about 400,000 lbf thrust vs. 80,000 lbf for the Castor 30). There are better Lox-kerosene engines for the Taurus II second stage from the thrust matching standpoint with equal or better Isp and good enough T/W (e.g. RD-0124 at 66,000 lbf thrust, Isp = 359 s, T/W = 63 with TVC and controller)Apparently, it would be fairly illogical.
NK-43 It is not too optimum for a rocket of type Taurus II. 1) Its application conducts to "ugly" distribution of weights between stages by optimisation of key parametres of a rocket. 2) excessively high T/W negatively affects weight of the payload deduced into orbits in height more of 150 miles.
Propellants: Lox/Kerosene. Thrust(vac): 402.000 kN (90,373 lbf). Isp: 353 sec. Burn time: 1,200 sec. Mass Engine: 722 kg (1,591 lb). Diameter: 1.40 m (4.50 ft). Thrust to Weight Ratio: 56.78
Quote from: mmeijeri on 04/02/2010 04:09 pmWould it have been possible to use two AJ-10's?If you place two of them within the 3.7 m internal diameter of Taurus II, a significant part (about 20%) of the each bell's heat radiates towards the other bell. This may not seem a lot, but over the burn duration it is more than enough for the bell temperature to go way, way beyond the material limit.Again, this is a big time thermal problem that would require extensive analysis, very probable modifications, and the ensuing verification and test.
We also looked at that. In addition to the cost (these are not exactly inexpensive engines, especially considering they are pressure-fed), their exit diameter (1.7m) would place them very, very close to each other.
Is this really such a problem? The Transtage of Titan III heritage featured two AJ10 side by side on a 3.05 m core
May be NK-31 with TVC?
(how they got two 1.53m nozzles within a 3.05m OUTSIDE DIAMETER airframe I cannot explain, but the Titan transtage was one bizarre bird, with asymmetrical N2O2 and Fuel tanks...)