Author Topic: Pegasus II  (Read 15430 times)

Offline Kabloona

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Pegasus II
« on: 08/13/2013 07:39 PM »
Thanks to Chris for this informative article on plans for Pegasus II.

http://www.nasaspaceflight.com/2013/08/orbital-atk-solid-partnership-stratolaunch-alv/

Let the discussion begin!

Offline Chris Bergin

Re: Pegasus II
« Reply #1 on: 08/13/2013 08:02 PM »
Thanks! But the larger version covering more of the vehicle is this one:
http://www.nasaspaceflight.com/2013/05/stratolaunch-orbital-air-launch/

Offline Kabloona

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Re: Pegasus II
« Reply #2 on: 08/13/2013 08:10 PM »
Thanks again, Chris.

I am puzzled, though, by an apparent contradiction between the text and the artist's concept showing the wing and fin locations. The article says,

"The wing will be located on the top of the first stage, while the inverted-V tails share a commonality with Pegasus, albeit at a different angle, so as not to be blanketed by the wings during high angles of attack."

But the artist's concept shows the wing on the *underside* of Stage 1, with a V-tail that is *not* inverted, but upright.

So the artist's concept shows the exact opposite of what the text describes. If the vehicle shown in the concept were rolled 180 degrees, then it would seem to match the text description, with wing on top and V-tails inverted.

Chris, do you have any insight into this apparent discrepancy?

« Last Edit: 08/13/2013 08:22 PM by Kabloona »

Offline robertross

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Re: Pegasus II
« Reply #3 on: 08/13/2013 08:16 PM »
Great stuff Chris!

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

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Re: Pegasus II
« Reply #4 on: 08/13/2013 08:26 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. ;-)
« Last Edit: 08/13/2013 08:30 PM by Kabloona »

Offline Chris Bergin

Re: Pegasus II
« Reply #5 on: 08/13/2013 09:28 PM »
Thanks again, Chris.

I am puzzled, though, by an apparent contradiction between the text and the artist's concept showing the wing and fin locations. The article says,

"The wing will be located on the top of the first stage, while the inverted-V tails share a commonality with Pegasus, albeit at a different angle, so as not to be blanketed by the wings during high angles of attack."

But the artist's concept shows the wing on the *underside* of Stage 1, with a V-tail that is *not* inverted, but upright.

So the artist's concept shows the exact opposite of what the text describes. If the vehicle shown in the concept were rolled 180 degrees, then it would seem to match the text description, with wing on top and V-tails inverted.

Chris, do you have any insight into this apparent discrepancy?



Yeah! :)

The info is bang up to date (per the first article), but the graphics are not. Makes sense as it probably took them a long time to create that video the slides are taken from.

Offline Kabloona

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Re: Pegasus II
« Reply #6 on: 08/13/2013 09:42 PM »
Thanks again, Chris.

I am puzzled, though, by an apparent contradiction between the text and the artist's concept showing the wing and fin locations. The article says,

"The wing will be located on the top of the first stage, while the inverted-V tails share a commonality with Pegasus, albeit at a different angle, so as not to be blanketed by the wings during high angles of attack."

But the artist's concept shows the wing on the *underside* of Stage 1, with a V-tail that is *not* inverted, but upright.

So the artist's concept shows the exact opposite of what the text describes. If the vehicle shown in the concept were rolled 180 degrees, then it would seem to match the text description, with wing on top and V-tails inverted.

Chris, do you have any insight into this apparent discrepancy?



Yeah! :)

The info is bang up to date (per the first article), but the graphics are not. Makes sense as it probably took them a long time to create that video the slides are taken from.

OK, thanks. Maybe they figured out after the artwork was done that the V-tail would work better inverted, where it would be in a "clean" airstream when pitching up. I guess that's what your text is saying.
« Last Edit: 08/13/2013 09:56 PM by Kabloona »

Offline Calphor

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Re: Pegasus II
« Reply #7 on: 08/14/2013 04:19 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.

Offline Kabloona

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Re: Pegasus II
« Reply #8 on: 08/14/2013 01:14 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.

Offline robertross

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Re: Pegasus II
« Reply #9 on: 08/14/2013 03:09 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?
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

Offline Kabloona

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Re: Pegasus II
« Reply #10 on: 08/14/2013 03:22 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.

Offline Lee Jay

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Re: Pegasus II
« Reply #11 on: 08/14/2013 03:43 PM »
I'm trying to figure out where this vehicle sits given Antares.  Is this designed to replace Antares if the Antares first stage has to be retired when the engines run out and they can't find a suitable substitute?  Is there another reason to do this of which I am unaware?

Offline baldusi

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Re: Pegasus II
« Reply #12 on: 08/14/2013 04:35 PM »
First, remember that this is a Stratolauncher vehicle, were OSC is prime contractor. This means that the IP most probably belongs to Stratolaunch. Also, it's a lot easier to do a solid air launched first stage than a liquid. Else you start to get into issues of boil off, stability and abort complications.
Then, it might happen that the Zenit tooling doesn't lends itself to the sort of efforts that a hanging configuration has. In fact a the Soviet air launched concepts were from the top of a plane. So it's quite probable that the minimum investment design was going with solids. Specially since OSC has the Pegasus experience that they have.
Just doing an H2 US for this vehicle will be a problem big enough.

Offline Robotbeat

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Re: Pegasus II
« Reply #13 on: 08/14/2013 05:10 PM »
I'm trying to figure out where this vehicle sits given Antares.  Is this designed to replace Antares if the Antares first stage has to be retired when the engines run out and they can't find a suitable substitute?  Is there another reason to do this of which I am unaware?
Because you can make the biggest airplane evar? ;)

Antares exists to fill the vacuum of Delta II that Orbital needs to launch their own birds domestically. Orbital has to pay for Antares. This Pegasus II, it seems, is being financed by Stratolaunch, which is /paying/ Orbital (from what I can tell). This is a better deal for Orbital than Antares is!

Launch vehicles and the infrastructure required is expensive. Here, you have an airplane that can allow efficient launches with basically all-domestic components to any inclination without having to build multiple launch sites. For Orbital, a great deal. For Paul Allen, this is a cheap way of getting the concept off the ground (heh) and launching stuff. They can always upgrade the concept at a later time. A better/cheaper upper stage, a higher performance liquid first stage (hydrolox is best, fueled in-flight), recoverable stages, etc.

And good for them. Now we just need to expand the launch demand somehow.
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Offline yg1968

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Re: Pegasus II
« Reply #14 on: 08/14/2013 06:20 PM »
I'm trying to figure out where this vehicle sits given Antares.  Is this designed to replace Antares if the Antares first stage has to be retired when the engines run out and they can't find a suitable substitute?  Is there another reason to do this of which I am unaware?

I don't think that it's a replacement. My understanding is that Stratolaunch owns the IP rights related to Pegasus II. So Orbital cannot decide to transform Pegasus II into a competing rocket.

Offline Robotbeat

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Re: Pegasus II
« Reply #15 on: 08/14/2013 07:06 PM »
I asked this on an L2 thread, but this is a better place:

What about a kerolox first stage filled via aerial refueling (assuming we can make Stratolaunch and the rocket use the same fuel)? By also allowing the Stratolaunch aircraft to launch nearly dry, this could allow a significantly greater payload to orbit.
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Online Zed_Noir

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Re: Pegasus II
« Reply #16 on: 08/14/2013 08:53 PM »
I asked this on an L2 thread, but this is a better place:

What about a kerolox first stage filled via aerial refueling (assuming we can make Stratolaunch and the rocket use the same fuel)? By also allowing the Stratolaunch aircraft to launch nearly dry, this could allow a significantly greater payload to orbit.

First someone have to set up a fleet of Jumbo jet size tankers and test if you can get Birdzilla & Jumbo to do close proximity formation flying. Smaller size aerial tankers might have turbulence issues along with excessive link ups and total connection time.

Don't see a need to have common kero for the Stratolaunch aircraft and the LV. There should be enough volume to have two set of kero tankage.

Maybe a LOX pod on top of the middle of the wing can top up the LV before launch.

Offline Robotbeat

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Re: Pegasus II
« Reply #17 on: 08/14/2013 09:06 PM »
I asked this on an L2 thread, but this is a better place:

What about a kerolox first stage filled via aerial refueling (assuming we can make Stratolaunch and the rocket use the same fuel)? By also allowing the Stratolaunch aircraft to launch nearly dry, this could allow a significantly greater payload to orbit.

First someone have to set up a fleet of Jumbo jet size tankers and test if you can get Birdzilla & Jumbo to do close proximity formation flying. Smaller size aerial tankers might have turbulence issues along with excessive link ups and total connection time.

Don't see a need to have common kero for the Stratolaunch aircraft and the LV. There should be enough volume to have two set of kero tankage.

Maybe a LOX pod on top of the middle of the wing can top up the LV before launch.
Common kero because it means fewer connections, mostly. Unfortunately, most of the weight of a liquid launch vehicle is actually LOx, not kerosene...

EDIT: Again, it's noting that the KC-10 has enough kerosene capacity (160mT) to totally fill up an Atlas V, though it would take a while (over half an hour, I think). KC-10s can refuel very large aircraft, so I see no fundamental reason why it couldn't refuel the Stratolauncher (which could in turn fuel up a kerolox rocket). It's more complication, sure, but it is one way to improve the payload capability without needing a bigger airplane.

And Air Force-1 is aerial-refuelable while also being 747-based (like Stratolaunch). Doesn't mean it's going to be easy. There is also a civil aerial refueling company (http://www.omegaairrefueling.com/) that does some of this, though their planes don't have the same capacity (more like 80mT) and use drogues instead of a boom like you'd want. It's estimated that aerial refueling costs about $20-50/gallon (including capitalization) for the military, so it's still a tiny fraction of the cost of the launch.
« Last Edit: 08/14/2013 09:46 PM by Robotbeat »
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Offline Proponent

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Re: Pegasus II
« Reply #18 on: 08/14/2013 09:08 PM »
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.

Maybe it's just dyed green, so it can be advertised as a "green" propellant. :)

Offline Calphor

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Re: Pegasus II
« Reply #19 on: 08/15/2013 12:03 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.

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 »
AD·ASTRA·ASTRORVM·GRATIA

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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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  :)

AD·ASTRA·ASTRORVM·GRATIA

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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