Author Topic: Antares A-One General Discussion Thread (2)  (Read 63368 times)

Offline Prober

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Re: Antares A-One General Discussion Thread (2)
« Reply #100 on: 04/21/2013 03:16 pm »
Fantastic detail.  Much appreciated.

I 2nd this, and would add thanks for taking your time to explain this.
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Offline jsmjr

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Re: Antares A-One General Discussion Thread (2)
« Reply #101 on: 04/21/2013 03:29 pm »
Fantastic detail.  Much appreciated.

I 2nd this, and would add thanks for taking your time to explain this.

Ditto - and I'd love to hear how those same types of calculations go into the designation of keep-out zones.  Seems to me some of our favorite viewing sites might get closed down on future flights depending on chemicals carried, wind direction, etc.  Did something similar happen mid-countdown yesterday over on Assateague?

Offline deltaV

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Re: Antares A-One General Discussion Thread (2)
« Reply #102 on: 04/21/2013 03:35 pm »
Surface winds AT THE PAD affect the clearance during lift-off.  Orbital has established a basic 15kts limit for ANY DIRECTION, waivable to 20kts by LD (Eberly).  Eberly has a "pocket reserve" of a few kts if the wind direction is "away from the TEL."  The range helps LD with the go/nogo decision (including computing its effect on POV) but this is not a range decision - it's Orbital's.

In the update thread you mentioned a roughly 20% probability of excess surface winds. Are there any other weather criteria that you're particularly concerned about today?
« Last Edit: 04/21/2013 03:35 pm by deltaV »

Offline jnc

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Re: Antares A-One General Discussion Thread (2)
« Reply #103 on: 04/21/2013 03:39 pm »
I hope this clarifies a bit what is admittedly a very complex situation.

Yes, very much. Thanks again!

Best wishes for today: we've all (I'm sure :-) got our fingers crossed for you all that i) you manage to launch, and ii) that the flight goes well.

Noel
« Last Edit: 04/21/2013 03:39 pm by jnc »
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Online Lee Jay

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Re: Antares A-One General Discussion Thread (2)
« Reply #104 on: 04/21/2013 03:47 pm »
All U.S. ranges agreed to add up the E sub C of each effect and use a composite criterion (100 per million) as a range go/no go criterion.

Thank you.

Is this 100 per million launches or 100 per million launch failures?  In other words, does it include or exclude the probability of launch failure?

Offline antonioe

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Re: Antares A-One General Discussion Thread (2)
« Reply #105 on: 04/21/2013 03:54 pm »
I believe it ASSUMES a failure...
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Offline Garrett

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Re: Antares A-One General Discussion Thread (2)
« Reply #106 on: 04/21/2013 04:11 pm »
Thanks for your excellent post Antonio.

Looking forward to a great launch today!
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Online meekGee

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Re: Antares A-One General Discussion Thread (2)
« Reply #107 on: 04/21/2013 04:23 pm »
It's obviously a very different machine from the ULA launchers or Falcon-9.  Would I be right in saying that the core will get almost all the way to orbit and the U/S is little more than a kick stage to get the perigee up?

You know, I don't understand the choice of a solid U/S.  It seems to have all the wrong attributes for an U/S.

Solids, IIUC, have a high "dry" weight, since the entire "tank" is thick walled.  And in an U/S, every pound wasted is 100% at the expense of payload.

Also, it burns to depletion, so you can't control end-of-burn, so I'd think that precision insertion is problematic.

Lastly, it is not a high ISP solution.

I always thought that solids are good as either high-thrust boosters, or BEO kick stages since they are simple and can last a long time in orbit.

Anyone familiar with why they went with a solid U/S?
As Jim answered, the answer is "cost".  The ultimate Antares second stage will be Castor 30XL, a stretched version that reportedly only cost $57 million to develop.  That's probably not much more than it costs to build and fly one or two Centaur stages.  Centaur, of course, cost far more than $57 million to develop, but that cost has been amortized over decades of flights by many stages now.  Orbital did not have that luxury.

Speaking of Centaur, Castor 30XL will have a better propellant mass ratio than that well-regarded and very successful liquid hydrogen upper stage.  That "high dry weight" often associated with solid motors does not apply in this case, nor for many of the modern day solid motors.

Centaur, of course will generate much more specific impulse than Castor 30XL, but the improved Antares second stage will still produce more than 75% as much total impulse as Centaur.  Castor 30XL will produce 3.8 times more total impulse than the Delta 2 second stage while having a far better PMF than that pressure fed stage. 

Castor 30XL is a high performance graphite epoxy case solid motor with a huge nozzle designed to extract maximum performance.  It provides that performance without need for any cryogenic propellant handling or loading at the pad.  It is a good deal for Orbital, which is trying hard to develop a rocket that can make money flying only a few times per year. 

 - Ed Kyle

Wall, all I can say is the the numbers are pretty harsh.

The 30X has a mass fraction of 7.5%  - I think even the first stage of F9 does better.  (comparing it to old DII upper stage is not a good basis for comparison, is it?)

The unit cost of the US is then going to be higher, right?

Lastly, honestly, $57M doesn't sound that cheap for development cost.

Shrug. 

The point is, after it flies, it needs to compete. 
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Offline deltaV

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Re: Antares A-One General Discussion Thread (2)
« Reply #108 on: 04/21/2013 04:33 pm »
Here's a neat near-real-time graph of wind speeds (and gusts) on the nearby Chincoteague Island: http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KVACHINC2&day=21&month=04&year=2013 . Note that 20 knots = 23 mph.

Weather underground offers a marine forecast for the location "Wallops Island Rocket Launches": http://www.wunderground.com/sailing-weather/beach:Wallops%20Island%20Rocket%20Launches%2039182?MR=1 .
I'm guessing it knows about this from the notice to mariners about the launch.

Is the 20 knot limit a limit on sustained wind speed or gusts?
« Last Edit: 04/21/2013 04:41 pm by deltaV »

Offline antonioe

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Re: Antares A-One General Discussion Thread (2)
« Reply #109 on: 04/21/2013 04:47 pm »
Warning: typical weather data is obtained from anemometers located on a weather tower, at different levels.  We are directly looking at, and analyzing, anemometers located at the launch pad itself, so there WILL be a difference!
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Offline edkyle99

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Re: Antares A-One General Discussion Thread (2)
« Reply #110 on: 04/21/2013 04:48 pm »
Wall, all I can say is the the numbers are pretty harsh.

The 30X has a mass fraction of 7.5%  - I think even the first stage of F9 does better.  (comparing it to old DII upper stage is not a good basis for comparison, is it?)

The unit cost of the US is then going to be higher, right?

Lastly, honestly, $57M doesn't sound that cheap for development cost.

Shrug. 

The point is, after it flies, it needs to compete. 
Can't compare a first stage with a smaller upper stage.  Different animals.  And Falcon 9 is a bigger rocket in general.  But sure, a LOX/RP stage can be more mass efficient than a solid stage, but it can also cost more - maybe much more, both to develop and to fly.   How much do you think it will cost SpaceX to develop its v1.1 upper stage, which after all these years of engineering and testing has not yet flown?  Billions of dollars will have flown into this company during this time.

$57 million for a complete development program of an upper stage of this capability is cheap.  Orbital is going to probably garner close to $200 million gross income per COTS mission, roughly speaking.  If Antares flies 57 times, which is plausible, that development cost would amortize to $1 million per launch, but even less than that if inflation is considered.         

 - Ed Kyle
« Last Edit: 04/21/2013 04:55 pm by edkyle99 »

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Re: Antares A-One General Discussion Thread (2)
« Reply #111 on: 04/21/2013 05:35 pm »
Wall, all I can say is the the numbers are pretty harsh.

The 30X has a mass fraction of 7.5%  - I think even the first stage of F9 does better.  (comparing it to old DII upper stage is not a good basis for comparison, is it?)

The unit cost of the US is then going to be higher, right?

Lastly, honestly, $57M doesn't sound that cheap for development cost.

Shrug. 

The point is, after it flies, it needs to compete. 
Can't compare a first stage with a smaller upper stage.  Different animals.  And Falcon 9 is a bigger rocket in general.  But sure, a LOX/RP stage can be more mass efficient than a solid stage, but it can also cost more - maybe much more, both to develop and to fly.   How much do you think it will cost SpaceX to develop its v1.1 upper stage, which after all these years of engineering and testing has not yet flown?  Billions of dollars will have flown into this company during this time.

$57 million for a complete development program of an upper stage of this capability is cheap.  Orbital is going to probably garner close to $200 million gross income per COTS mission, roughly speaking.  If Antares flies 57 times, which is plausible, that development cost would amortize to $1 million per launch, but even less than that if inflation is considered.         

 - Ed Kyle

Wait - the entire F9, including engines, was about $300M, wasn't it?

And the US for the 1.1 is currently getting assembled onto it.

So when you say "which after all these years of engineering and testing has not yet flown" - are you referring to the Raptor engine? Because that's a foundation for an entire new set of rockets, and there's absolutely no indication it ate "Billions of Dollars", or that it has even been tested.

Or are you referring to the 1.1 ?  Since it hasn't exactly been "all these years of engineering and testing" - it's a pretty quick follow-on to the F9 1.0, with quite an enhanced set of capabilities.

But back to the solid, and irrespective of F9, it's not like ATK had to develop new fuel, or new casing, or new nozzle or actuation or avionics, or invest in facilities - they already make/have all this stuff.  So I'm saying $57M seems awfully rich, and I'm not sure the unit cost of the C30L will be any lower than a liquid U/S.


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Offline clongton

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Re: Antares A-One General Discussion Thread (2)
« Reply #112 on: 04/21/2013 05:47 pm »
Why is it counting up instead of down?
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Offline yg1968

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Re: Antares A-One General Discussion Thread (2)
« Reply #113 on: 04/21/2013 05:49 pm »
Why is it counting up instead of down?

The clock on the live webcast is a universal time clock.
« Last Edit: 04/21/2013 05:54 pm by yg1968 »

Offline Galactic Penguin SST

Re: Antares A-One General Discussion Thread (2)
« Reply #114 on: 04/21/2013 06:36 pm »
From OSC's Twitter account:

Quote
Orbital Sciences ‏@OrbitalSciences
Even though it will consume close to 1ton of prop every second after lift-off, the early acceleration will be surprisingly slow.

Quote
Orbital Sciences ‏@OrbitalSciences
When the engines first ignite, the rocket will not lift off from the pad for two full seconds.

Quote
Orbital Sciences ‏@OrbitalSciences
At 10 seconds after Stage 1 engine ignition the vehicle will have accelerated to about 40 mph and climbed to 230 feet altitude.

Quote
Orbital Sciences ‏@OrbitalSciences
At 20 seconds after ignition, #Antares will be traveling at 100 mph at be about 1,250 feet above the pad.

Quote
Orbital Sciences ‏@OrbitalSciences
Even after 60 seconds, the vehicle will still be subsonic (about 460 mph) at just over 3 miles in altitude. #Antares

Quote
Orbital Sciences ‏@OrbitalSciences
#Antares achieves Mach 1 about 75 seconds after lift-off, when it will be at about 30,000 feet in altitude.

Do we got a winner for the smallest T/W ratio of all rockets currently used? From Ed Kyle's data I got T/W= ~1.1 (!) (comparison: Saturn V is around 1.2 and the Atlas V 401 is ~1.28)  :o
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Offline yg1968

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Re: Antares A-One General Discussion Thread (2)
« Reply #115 on: 04/21/2013 06:42 pm »
upstream just went offline for me too

It's now back online. It's been going on and off line for a while.
« Last Edit: 04/21/2013 06:55 pm by yg1968 »

Offline antonioe

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Re: Antares A-One General Discussion Thread (2)
« Reply #116 on: 04/21/2013 06:44 pm »
Actually, the liftoff to 20 seconds data is surprisingly close to the Apollo 11 Saturn V numbers.  Then the Saturn V looses mass percentage faster than Antares due to the 3 stages vs. Antares only 2, then when S-V staged Antares outaccelerates S-V and the two trade acceleration leads through the rest of the staging sequence (remember, Saturn V stage 3 Earth Orbit MECO was about mid-depletion...)

DWT said that, if asked, he'll say that the Antares climb-out is "majestic" ...  :D
« Last Edit: 04/21/2013 06:46 pm by antonioe »
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Offline ugordan

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Re: Antares A-One General Discussion Thread (2)
« Reply #117 on: 04/21/2013 06:50 pm »
Actually, the liftoff to 20 seconds data is surprisingly close to the Apollo 11 Saturn V numbers.  Then the Saturn V looses mass percentage faster than Antares due to the 3 stages vs. Antares only

I thought Saturn V losing more mass % after 20 sec (but still during 1st stage!) would be due to lower Isp of F-1 vs. AJ-26?

Offline antonioe

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Re: Antares A-One General Discussion Thread (2)
« Reply #118 on: 04/21/2013 06:55 pm »
That, too.  But Antares' stage 1 is also larger in total percentage than S-V's stage 1 so it gets "depleted" slower w.r.t. the total mass of the rocket (stage 1 provides more of the total DV in Antares' case than S-V)

To tell you the thruth, I haven't run the numbers, so I don't know which effect is greater...
« Last Edit: 04/21/2013 06:56 pm by antonioe »
ARS LONGA, VITA BREVIS...

Offline yg1968

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Re: Antares A-One General Discussion Thread (2)
« Reply #119 on: 04/21/2013 06:57 pm »
Quote
[Question:] What wind speeds are considered too high for launch?

[Answer from Orbital:] Ground winds consistently above 20 knots (23 mph).

https://twitter.com/OrbitalSciences/status/326043289264459777
« Last Edit: 04/21/2013 07:01 pm by yg1968 »

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