Author Topic: Pegasus II  (Read 16045 times)

Offline Kabloona

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Re: Pegasus II
« Reply #20 on: 08/15/2013 12:45 PM »
Great stuff Chris!

For a moment there I thought ATK was using my recipe for Pistachio ice cream!  ;)

Yeah, that greenish cast is strange. I suspect it's just a color balance issue with the digital camera, as fluorescent lighting will make things look green if the color balance option on a digital camera isn't set correctly. Normally solid propellants in that condition look grayish due to the aluminum powder, and I doubt it was St Patrick's day at ATK when the photo was taken. ;-)

You'd be surprised then, that color is accurate. Shuttle propellant is actually red-brown. It all depends on the ingredients.

What is the green ingredient? I worked with solid propellants for ten years (in the nineties) and saw colors range from black to gray to reddish (iron oxide burn rate catalyst) but never green.

likely the binding agent has caused this colour cast?

Conventional binders (HTPB, PBAN) are not green, and IMO it's highly unlikely ATK would use a different binder given the extensive industry experience with HTPB and PBAN. More likely an oxidizer or some sort of energetic ingredient.

I don't know if it as been released in the open literature, but I can say that it is neither PBAN or HTPB.

I know it's not HTPB or PBAN because those are not green.  ;)
But can you say what the function of the green is? Binder, oxidizer, catalyst, energetic ingredient...?

Offline kevin-rf

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Re: Pegasus II
« Reply #21 on: 08/15/2013 01:16 PM »
Wouldn't stating which component causes the green color be just as much of a no no as stating what the green slime is?

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Offline R7

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Re: Pegasus II
« Reply #22 on: 08/15/2013 02:02 PM »
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Offline robertross

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Re: Pegasus II
« Reply #23 on: 08/15/2013 02:49 PM »
Burn rate modifier?

http://www.google.com/patents/US4411717

I don't think we need any other confirmation that that. Seems 100% logical.

Good one, thanks!
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Offline kevin-rf

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Re: Pegasus II
« Reply #24 on: 08/15/2013 03:00 PM »
We have no knowledge what color "Guignet's green pigment" is ;)
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Offline Kabloona

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Re: Pegasus II
« Reply #25 on: 08/15/2013 03:05 PM »
Burn rate modifier?

http://www.google.com/patents/US4411717

Interesting...good find. I see the patent was filed in 1983. I worked in solid propellant R&D in the 1990's and never heard of the stuff. Strange. It's never been used in any launch vehicle or ICBM that I'm aware of.
« Last Edit: 08/15/2013 03:17 PM by Kabloona »

Offline R7

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Re: Pegasus II
« Reply #26 on: 08/15/2013 03:50 PM »
I worked in solid propellant R&D in the 1990's and never heard of the stuff.

Chromium oxide then Cr2O3? Guignet green is basically same stuff but somehow hydrated form. The patent I linked refers to much older one that discusses mixture of chromium oxide + other metal oxides as burn modifiers.

Definitely green stuff  :)

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Offline Kabloona

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Re: Pegasus II
« Reply #27 on: 08/15/2013 04:23 PM »


Yes, I see it is indeed green. Well, if that's the mystery ingredient in the ATK photo, it raises the next question: what's the *real* mystery ingredient, i.e. the performance enhancer? Because burn rate catalyst contributes nothing to Isp, in fact it's dead weight, energetically speaking.

Anyway, apologies for dragging this thread OT. However, I think we've established that (a) the photo is of an ATK experimental formulation that might be considered for future SLS booster applications but is not ready for near-term use, and (b) it has nothing to do with Pegasus II.
« Last Edit: 08/15/2013 04:25 PM by Kabloona »

Offline Calphor

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Re: Pegasus II
« Reply #28 on: 08/16/2013 01:47 AM »
Great stuff Chris!

For a moment there I thought ATK was using my recipe for Pistachio ice cream!  ;)

Yeah, that greenish cast is strange. I suspect it's just a color balance issue with the digital camera, as fluorescent lighting will make things look green if the color balance option on a digital camera isn't set correctly. Normally solid propellants in that condition look grayish due to the aluminum powder, and I doubt it was St Patrick's day at ATK when the photo was taken. ;-)

You'd be surprised then, that color is accurate. Shuttle propellant is actually red-brown. It all depends on the ingredients.

What is the green ingredient? I worked with solid propellants for ten years (in the nineties) and saw colors range from black to gray to reddish (iron oxide burn rate catalyst) but never green.

likely the binding agent has caused this colour cast?

Conventional binders (HTPB, PBAN) are not green, and IMO it's highly unlikely ATK would use a different binder given the extensive industry experience with HTPB and PBAN. More likely an oxidizer or some sort of energetic ingredient.

I don't know if it as been released in the open literature, but I can say that it is neither PBAN or HTPB.

I know it's not HTPB or PBAN because those are not green.  ;)
But can you say what the function of the green is? Binder, oxidizer, catalyst, energetic ingredient...?

It's the binder.

Offline Kabloona

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Re: Pegasus II
« Reply #29 on: 08/16/2013 02:24 AM »

It's the binder.

Wow. A new binder for a large booster instead of PBAN or HTPB? That will be interesting...

Offline Kabloona

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Re: Pegasus II
« Reply #30 on: 08/16/2013 08:58 PM »
Maybe ATK will try to scale up the "green binder" propellant for Pegasus II?

"Our design solution for the ALV will take full advantage of ATK's experience with large diameter solid rocket motors, like those built for the space shuttle and for the Titan 4B launch vehicle," said Scott Lehr, vice president and general manager of ATK's defense and commercial division. "The stages for ALV will also use high-strength, low-weight graphite composite cases, advanced propellants, and heritage materials from ATK's extensive line of commercial solid rocket motors."
« Last Edit: 08/16/2013 08:59 PM by Kabloona »

Offline Llian Rhydderch

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Re: Pegasus II
« Reply #31 on: 12/06/2014 02:13 AM »
With lots of water under the bridge since Pegasus II was first announced, ATK merging with Orbital, proposed mini-Dream Chaser as a cargo, etc....

... what more do we know on Pegasus II that we did not know in August of 2013 when this was announced?
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Offline edkyle99

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Re: Pegasus II
« Reply #32 on: 12/06/2014 03:17 AM »
With lots of water under the bridge since Pegasus II was first announced, ATK merging with Orbital, proposed mini-Dream Chaser as a cargo, etc....

... what more do we know on Pegasus II that we did not know in August of 2013 when this was announced?
It is now an all-solid motor rocket (more like a real Pegasus II).  I'm not sure if the likelihood of its full development has risen or fallen since last year.

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