Author Topic: Orbital's Antares Development Update Thread  (Read 1064979 times)

Offline Ronsmytheiii

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Re: Taurus II Development News
« Reply #360 on: 04/02/2010 04:01 pm »
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...

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... ::)

I would believe it, even during drought season in Virginia the bottom of my backyard is always muddy (faces a creek)  Pretty much the entire Eastern coast is swampy and drainage ponds are needed for any building.

Offline mmeijeri

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Re: Taurus II Development News
« Reply #361 on: 04/02/2010 04:09 pm »
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.

Would it have been possible to use two AJ-10's? I'm sure you picked the right variant, just wondering about the tradeoffs.
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Offline antonioe

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Re: Taurus II Development News
« Reply #362 on: 04/02/2010 04:27 pm »

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

Unfortunately, we're in the "wheeling and dealing" phase with potential suppliers, as we were during the initial phases of the (basic) Taurus II development, so I can't report on how things are going.  Hang on, hang on!...

Because of this, ETA for public data on the Enhanced configuration is probably NET October.

Just one teasing hint: logic always, in the end, prevails...
ARS LONGA, VITA BREVIS...

Offline antonioe

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Re: Taurus II Development News
« Reply #363 on: 04/02/2010 04:41 pm »
Would it have been possible to use two AJ-10's?

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.  The bells are radiatevely-cooled, and in the Delta K configuration they have 360 degrees of view (radially, and about 150 degrees vertically) to radiate against.

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.
ARS LONGA, VITA BREVIS...

Offline strangequark

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Re: Taurus II Development News
« Reply #364 on: 04/02/2010 04:50 pm »

Just one teasing hint: logic always, in the end, prevails...

Hmm, the engine choice is logical. Vulcans are logical. Vulcan sounds like Vulcain...

Offline Jim

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Re: Taurus II Development News
« Reply #365 on: 04/02/2010 05:44 pm »

Hmm, the engine choice is logical. Vulcans are logical. Vulcan sounds like Vulcain...


That would be illogical.   RL-10 is logical.

Offline strangequark

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Re: Taurus II Development News
« Reply #366 on: 04/02/2010 07:09 pm »

That would be illogical.   RL-10 is logical.

Yeah, but that one doesn't have any easy, geeky Star Trek references. From Antonio's earlier comment, it sounds like an RL-60 would fit the bill nicely with one engine. Not sure if that would be worth Orbital's while to fund it though, since, as you alluded to, 2 RL-10s would work just fine.

Offline William Barton

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Re: Taurus II Development News
« Reply #367 on: 04/02/2010 07:13 pm »
So. How much logic would NK-43/AJ-26-60 have?

Offline strangequark

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Re: Taurus II Development News
« Reply #368 on: 04/02/2010 07:15 pm »
So. How much logic would NK-43/AJ-26-60 have?

Antonio mentioned this a while back:

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)

Apparently, it would be fairly illogical.
« Last Edit: 04/02/2010 07:15 pm by strangequark »

Offline William Barton

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Re: Taurus II Development News
« Reply #369 on: 04/02/2010 07:21 pm »
So. How much logic would NK-43/AJ-26-60 have?

Antonio mentioned this a while back:

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)

Apparently, it would be fairly illogical.

Ah. I forgot. Although I do wonder why "5 times too big." Kistler was going to use 3x NK-33 on s1 and 1x NK-43 on S2. Seems like it should only be 2 times too big or something. I suppose it can't be throttled...

Offline Antares

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Re: Taurus II Development News
« Reply #370 on: 04/02/2010 07:28 pm »
The Kistler second stage had a lot of extra weight for reusability.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline Dmitry_V_home

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Re: Taurus II Development News
« Reply #371 on: 04/02/2010 07:38 pm »
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.


Offline Danderman

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Re: Taurus II Development News
« Reply #372 on: 04/02/2010 08:09 pm »
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.



As mentioned before, NK-43 is too big, but NK-39 would be just right.

Offline Salo

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Re: Taurus II Development News
« Reply #373 on: 04/02/2010 08:20 pm »
May be NK-31 with TVC?
http://www.astronautix.com/engines/nk31.htm
Quote
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



http://sntk-odk.ru/production/zhrd.html

Offline Skyrocket

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Re: Taurus II Development News
« Reply #374 on: 04/02/2010 08:29 pm »
Would 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.

Is this really such a problem? The Transtage of Titan III heritage featured two AJ10 side by side on a 3.05 m core
« Last Edit: 04/02/2010 11:30 pm by Skyrocket »

Offline mmeijeri

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Re: Taurus II Development News
« Reply #375 on: 04/02/2010 08:48 pm »
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. 

Do you mean that even though you would expect it to be cheap since it is pressure-fed (and hypergolic, ablative/radiative, noncryogenic ...) it is in fact expensive? Any ideas why it is so expensive?
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Offline antonioe

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Re: Taurus II Development News
« Reply #376 on: 04/03/2010 03:18 am »
(warning: contains hearsay): materials and labor, I'm told.  Like the P&W RL-10, the Aerojet AJ-10 was designed during a period of time when labor was cheap and complex machine tools expensive and unreliable (i.e.before digital computers).  In the case of the RL-10, I know that PWR has been desperately trying to get somebody to pay for a major upgrade of the that, among other things, does away with the painstakingly beautiful but high-cost hand-molded and hand-brazen tube-formed nozzle and early bell...

(Before somebody asks the question "why don't they pay for that improvement out of their own - or mother United Technologies' - pocket?" I will answer it :)  Very simple: there is no credible business case for PWR to do so without major customer financial support or committment...)
ARS LONGA, VITA BREVIS...

Offline antonioe

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Re: Taurus II Development News
« Reply #377 on: 04/03/2010 03:41 am »
Is this really such a problem? The Transtage of Titan III heritage featured two AJ10 side by side on a 3.05 m core

Ah, Gunter!  Your encylopedic mastery strikes again!... ;) O.K., I had to do a little sleuthing here... this is Monday night engineering, but since you've teased me...

The Titan transtage had two -138 version engines.  the -138 had shorter and much thicker bells than the current generation -118K engines.  At 40:1 expansion ratio (vs. 65:1 for the -118K) it is smaller (1.53m diameter vs. 1.70m) and had lower vacuum thrust (35Klbf vs. 43Klbf) and Isp (311s vs. 320 s.) but it was much beefier (110 Kg. vs 98Kg for the larger-nozzleed -118K).  Finally, it ran much more Oxidizer rich (2.0 O/F ratio) than the -118 (1.9).

I guess all of these differences reduced the thermal radiative load of the nozzle enough to allow the side-by-side installation on the transtage (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...)  Now, I didn't make up the concern about radiational re-heating of the side-by-side -118K nozzles... we actually analyzed it (no hearsay.)
« Last Edit: 04/03/2010 03:53 am by antonioe »
ARS LONGA, VITA BREVIS...

Offline antonioe

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Re: Taurus II Development News
« Reply #378 on: 04/03/2010 03:45 am »
May be NK-31 with TVC?

(*Sniff*...) Brings me back memories of the X-34... :'( (somebody get me a Kleenex, please)
« Last Edit: 04/03/2010 03:53 am by antonioe »
ARS LONGA, VITA BREVIS...

Offline Oberon_Command

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Re: Taurus II Development News
« Reply #379 on: 04/03/2010 04:32 am »
(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...)

Is it possible that they could have gimbaled the engines towards each other in order to fit the two nozzles into that small diameter? Like, if they spaced the engines out enough so that prior to staging, the engines could be gimbaled such that the "inner" edges of the nozzles could be almost touching each other while the "outer" edges of the nozzles were pulled in enough to avoid touching the interstage. What I'm thinking is that if they were to do that, all they'd have to do after staging is move the engines into their correct flight position, which would leave the "outer" edges of the nozzles "outside" the 3.05m diameter of the interstage. I'm not an expert, but it seems like a simple (in concept if not execution!) problem of geometry. Though, I'm looking at this photo and I'm not sure if there's enough space (or gimbal range) between the engines to allow them to do something like this.

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