Author Topic: CASTOR 30XL prepares for static fire ahead of providing Antares boost  (Read 28489 times)


Offline Lee Jay

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Can't wait to follow its flights on NSF!

Online Galactic Penguin SST

I am pretty sure that this will surely get the tin can swan a huge kick in the, um, bottom! (not unlike the many other small solid upper stages, except we should get live rocketcam this time!  8))
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline Todd Martin

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Since a solid 2nd stage is less precise in placing a payload into orbit than a Liquid, I wonder how Cygnus compares to Dragon in delta V.  It seems reasonable to expect that Cygnus will need more flexibility to reach ISS.  The lack of precision in orbital insertion could also mean that the target "drop off" point for Antares is further from ISS than what Falcon 9 is permitted?


Offline sdsds

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That was fun to write.

That was fun to read! Two quick questions for those of us not totally familiar with this stuff:
1. What does the phrase, " dual density exit cone" mean?
2. Is the " Large Class Stage program" the USAF effort that led to the Castor 30 initially, before Orbital became involved with it?

Since a solid 2nd stage is less precise in placing a payload into orbit than a Liquid

It isn't totally obvious that's true. Clever thrust vectoring algorithms can control the velocity at motor cut-off even without the ability to terminate thrust early or otherwise alter the total impulse provided by the motor.
-- sdsds --

Offline AnimatorRob

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Since a solid 2nd stage is less precise in placing a payload into orbit than a Liquid, I wonder how Cygnus compares to Dragon in delta V.  It seems reasonable to expect that Cygnus will need more flexibility to reach ISS.  The lack of precision in orbital insertion could also mean that the target "drop off" point for Antares is further from ISS than what Falcon 9 is permitted?



It has been explained to me in the past that the total impulse of a solid is actually very well known and that any mid-course corrections can either be made by altering the first stage burn or the trajectory on the the second stage.

Offline DavidH

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Work is being done for Solar Probe Plus:
http://solarprobe.jhuapl.edu/mission/docs/SolarProbeME.pdf
which adds TVC to the Star 48B to make a Star 48BV.

Is there any reason to think Cygnus would need TVC and the Star 48BV?

Section 3.1.7
Quote
The ATK STAR-48BV stage is a thrust-vector-controlled motor offering a simple control system and higher performance than the spinning STAR-48B, which has been used in programs such as New Horizons. The STAR-48BV uses a loaded motor case from the flight-proven STAR-48B, with nozzle design qualified for the Conestoga program and a newly developed thrust vector actuator (TVA) control system currently being qualified to support vectorable nozzles across the STAR product line. The nozzle and thrust vector control system will be used on a STAR-37FMV in mid-2008, and the STAR-48BV upper stage currently is under contract and scheduled for a first flight as part of the Minotaur IV launch vehicle.
TL;DR
Keep your posts short if you want them to be read.

Offline Todd Martin

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It has been explained to me in the past that the total impulse of a solid is actually very well known and that any mid-course corrections can either be made by altering the first stage burn or the trajectory on the the second stage.
[/quote]

Total impulse does not fully determine payload insertion height, since launch performance is affected by atmospheric pressure, temperature, and cross-winds.  I'm sure alterations to the 1st stage burn helps and the trajectory on the 2nd could help as well to some extant.  I am less convinced that thrust vector control will be significantly helpful since the CASTOR 30XL has only 1 nozzle.

Offline Jim

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The Cygnus will act as a third stage and trim out any dispersions.  It has an SM based on the STAR spacecraft bus. There will be a third stage or trim stage for other missions or the payload will have to handle the dispersions.

But what does have one nozzle have to do with TVC not being helpful. 
« Last Edit: 03/06/2013 03:53 PM by Jim »

Offline Todd Martin

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The Cygnus will act as a third stage and trim out any dispersions.  It has an SM based on the STAR spacecraft bus. There will be a third stage or trim stage for other missions or the payload will have to handle the dispersions.

But what does have one nozzle have to do with TVC not being helpful. 

Thanks for clarifying about the 3rd stage SM.  TVC with 1 nozzle is perfectly capable of keeping a rocket pointed in the right direction.  TVC with 2 or more nozzles could use Cosine losses to reduce effective thrust and hence orbital height.  With just 1 nozzle, the only way I can see to use TVC as a means to adjust orbital insertion height is to "Tack" the entire rocket back and forth.  IMHO, that sounds challenging to guidance, slow and cumbersome. 

Offline strangequark

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The Cygnus will act as a third stage and trim out any dispersions.  It has an SM based on the STAR spacecraft bus. There will be a third stage or trim stage for other missions or the payload will have to handle the dispersions.

But what does have one nozzle have to do with TVC not being helpful. 

Thanks for clarifying about the 3rd stage SM.  TVC with 1 nozzle is perfectly capable of keeping a rocket pointed in the right direction.  TVC with 2 or more nozzles could use Cosine losses to reduce effective thrust and hence orbital height.  With just 1 nozzle, the only way I can see to use TVC as a means to adjust orbital insertion height is to "Tack" the entire rocket back and forth.  IMHO, that sounds challenging to guidance, slow and cumbersome. 

It's called an energy scrub maneuver, and it is done routinely.

Offline Jim

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Also, there is the IUS method.  The SRM's were sized smaller than what was required, so that a overperformance would not result in a problem.  The RCS tanks were sized to make up the shortfall in case of a under or nominal motor performance.

Offline PahTo

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Good article and thread! 

What improvements are there from the 30/30A to the 30B? 

Does "a submerged design" mean the nozzle throat is actually touching/within the grain of the prop?

Curious about the "dual density exit cone" as well.  Perhaps the ablative material of the cone wall is thicker to stand up to the higher thrust?

As I'm not sure of the specs for 30A/30B, the reference to "stretched" indicates the XL is a higher thrust, but not a longer burn-time, motor.

Offline simonbp

They'll be using the (new) solid test stand at AEDC, right? I remember climbing all over that at an open house back before it had even been used for a test. The old solid test stand was destroyed in the 90s when a Minuteman stage detonated during a late-night test. They really put a lot of effort into making the new stand much more durable (and put it out at the edge of the facility).

Offline Jim

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Does "a submerged design" mean the nozzle throat is actually touching/within the grain of the prop?


It means the nozzle entrance extends to inside the motor case

Offline PahTo

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Thanks Jim.  I'm not sure why submerging the nozzle helps--perhaps makes TVC that much easier (both the physics of steering, as well as housing the TVC hardware).
I think it's safe to say the stretched casing carries more propellant as well as room for the nozzle (that is, they didn't just stretch to house the nozzle).

I realize how silly it sounds to ask if the nozzle was up at the grain of the prop. Then again, it does cause me to ponder the interface between the top of the nozzle and the bottom of the prop on any srm.

Speaking of prop, is there a dramatic difference between the chemical components of a solid used at sea level, and that used in vacuum?  On a simplistic level, is it still PBAN?  HTPB?  Some significantly different variation?

Online Chris Bergin

That was fun to write.

That was fun to read!

Thanks very much to both you and PahTo! :)

Online robertross

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Adding my vote on that great read Chris. Bravo.

Sounds like ATK really pulled out the stops to make that Castor a reality. Can't wait to see it in action!
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

Online Zed_Noir

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Thanks Jim.  I'm not sure why submerging the nozzle helps--perhaps makes TVC that much easier (both the physics of steering, as well as housing the TVC hardware).
I think it's safe to say the stretched casing carries more propellant as well as room for the nozzle (that is, they didn't just stretch to house the nozzle).

I realize how silly it sounds to ask if the nozzle was up at the grain of the prop. Then again, it does cause me to ponder the interface between the top of the nozzle and the bottom of the prop on any srm.

Speaking of prop, is there a dramatic difference between the chemical components of a solid used at sea level, and that used in vacuum?  On a simplistic level, is it still PBAN?  HTPB?  Some significantly different variation?

Check out pg 26 & pg 27 of the current ATK Motors PDF catalog for more info on the Castor 30A & Castor 30B. There's a cutaway diagram of the Castor 30B internal layout.

http://www.atk.com/wp-content/uploads/2013/02/ATK-Motor-Catalog-2012.pdf

By the way on pg 6 of the PDF is size comparison chart of current ATK rocket motors.

note - page number is what's on the page not the PDF page count

Offline Calphor

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Thanks Jim.  I'm not sure why submerging the nozzle helps--perhaps makes TVC that much easier (both the physics of steering, as well as housing the TVC hardware).
I think it's safe to say the stretched casing carries more propellant as well as room for the nozzle (that is, they didn't just stretch to house the nozzle).

I realize how silly it sounds to ask if the nozzle was up at the grain of the prop. Then again, it does cause me to ponder the interface between the top of the nozzle and the bottom of the prop on any srm.

Speaking of prop, is there a dramatic difference between the chemical components of a solid used at sea level, and that used in vacuum?  On a simplistic level, is it still PBAN?  HTPB?  Some significantly different variation?
The propellant is essentially the same whether the motor is used at sea level or in vacuum. IIRC, the propellant in this case is HTPB.

The submerged nozzle is used primarily to reduce motor length. It introduces some issues, but it is commonly used on modern motors.

Offline spectre9

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Excellent article.

ATK has done a good job.

Nozzle almost looks like a straight cone.

So the motor pictured is the one they're going to static fire?

Offline kevin-rf

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The submerged nozzle is used primarily to reduce motor length. It introduces some issues, but it is commonly used on modern motors.
Doesn't it also reduce the length of the interstate, reducing vehicle weight?
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Offline Antares

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Doesn't it also reduce the length of the interstate, reducing vehicle weight?

That's the most drastic sequester move yet.
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 kevin-rf

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Doh, Interstage!!!

As long as they don't take out MARS LP-0A on-ramp to space we should be good ;)
If you're happy and you know it,
It's your med's!

Online Chris Bergin

Excellent article.

ATK has done a good job.

Nozzle almost looks like a straight cone.

So the motor pictured is the one they're going to static fire?

Thanks! And yep - this is the static fire motor, which will be followed by six production motors that will fly with Antares.

Offline PahTo

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Thanks for all the info/links--NSF rocks as usual.  Best to the OSC/ATK/Antares team!
« Last Edit: 03/07/2013 02:41 PM by PahTo »

Offline baldusi

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The submerged nozzle is used primarily to reduce motor length. It introduces some issues, but it is commonly used on modern motors.
Doesn't it also reduce the length of the interstate, reducing vehicle weight?
Antares doesn't have an interstage per se, it encloses the payload and second stage in the 3.9m fairing. Having said that, it does allows for more volume for the payload and reduces the second stage support structure.

Offline renclod

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...
The submerged nozzle ... introduces some issues, ...


Such as slag accumulation in the volume between the casing and the submerged part of the nozzle, right ?

On the plus side, a submerged nozzle design is more "quiet", correct ?


Offline Kabloona

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The submerged nozzle is used primarily to reduce motor length. It introduces some issues, but it is commonly used on modern motors.
Doesn't it also reduce the length of the interstate, reducing vehicle weight?

Yes, the purpose of the submerged nozzle is to reduce overall length. The Castor 30XL is a derivative of the Castor 120 (MX Stage 1 derivative), and the MX was designed to be as compact as possible, no expense spared. The submerged nozzle design for the Castor 120 got carried over into the Castor 30.

Coincidentally, the solids for Pegasus were adapted from the Trident DII (D-5) sub-based ICBMs, for which compact design was even more essential. I don't recall off the top of my head, but those are likely submerged nozzle designs as well.

Submerged nozzle design is especially useful in upper stages where expansion ratios are larger and nozzles are longer and interstages are involved.
« Last Edit: 03/09/2013 02:26 PM by Kabloona »

Offline Kabloona

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I realize how silly it sounds to ask if the nozzle was up at the grain of the prop. Then again, it does cause me to ponder the interface between the top of the nozzle and the bottom of the prop on any srm.

Speaking of prop, is there a dramatic difference between the chemical components of a solid used at sea level, and that used in vacuum?  On a simplistic level, is it still PBAN?  HTPB?  Some significantly different variation?

The grain is designed such that max nozzle deflection leaves adequate clearance for the hot combustion gases to "turn the corner" and flow into the nozzle throat. The main concern in that area is "erosive" burning, in which high velocity hot combustion gases flowing over the grain surface cause the grain to burn too fast in a localized area. So the clearances there are carefully designed to avoid erosive burning.

As for propellant chemistry, the propellant doesn't know the difference between sea level and altitude, so there's no point in varying the chemistry for altitude. Upper stages with the same chemistry as lower stages will deliver higher Isp simply because vacuum conditions allow higher expansion ratios, which improve Isp.

The MX (Peacekeeper) ICBM did have different propellants on each stage, but that was mainly because each stage was developed by a different contractor.
« Last Edit: 03/09/2013 02:19 PM by Kabloona »

Offline Kabloona

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Coincidentally, the solids for Pegasus were adapted from the Trident DII (D-5) sub-based ICBMs, for which compact design was even more essential. I don't recall off the top of my head, but those are likely submerged nozzle designs as well.
I've always thought that the Orion motor series was more closely related to the Small ICBM ("Midgetman") development effort, though they don't seem to be direct copies of anything in particular.  SICBM was 46 inches in diameter.  Trident D2 is 83 inches diameter.  The Orion 50 motors are 50.5 inches diameter.  What these all shared were innovative carbon carbon composite motor cases, along with high expansion ratio nozzles and advanced propellant formulations.


No, Hercules leveraged their Trident II (D5) case technology to develop the Pegasus motors. The diameters were different, but they used the same graphite/epoxy case winding materials and methods.

Propellants are completely different, though, for safety reasons. D5 uses a high energy propellant containing HMX, which is too detonable for use in boosters. For the Orion motors, they switched to a safer AP/HTPB formulation.
« Last Edit: 03/10/2013 02:46 AM by Kabloona »

Offline simonbp

D5 uses a high energy propellant containing HMX, which is too detonable for use in boosters.

Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

Offline Jim

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Weapon systems have different design requirements

Offline R7

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Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

Yeah, and not just Tridents, the torpedoes are full of explosives too. HMX is insensitive. There's also nice safety clearance during launch. The submarine is ~50ft below surface while missile is catapulted way above surface before booster ignites. I'm dubious the whole grain could even detonate without some colossal casting error with all HMX clumped into one big chunk.
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Offline Kabloona

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D5 uses a high energy propellant containing HMX, which is too detonable for use in boosters.

Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

Well, this is a whole 'nother subject, but DoD wants the highest possible performance from their ICBMs, so they're willing to accept the risk of using propellants that contain high explosives like HMX, etc. These high-energy propellants (Class 1.1) are more hazardous than safer (Class 1.3) AP/HTPB propellants, but that doesn't mean you can detonate a D5 motor by just hitting it with a hammer. DoD has funded extensive research on the safety of high energy propellants, so they know exactly how to handle them.

If I were on a sub, I'd be more worried about the reactor than the D5.


« Last Edit: 03/11/2013 12:28 PM by Kabloona »

Offline Calphor

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D5 uses a high energy propellant containing HMX, which is too detonable for use in boosters.

Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

Well, this is a whole 'nother subject, but DoD wants the highest possible performance from their ICBMs, so they're willing to accept the risk of using propellants that contain high explosives like HMX, etc. These high-energy propellants (Class 1.1) are more hazardous than safer (Class 1.3) AP/HTPB propellants, but that doesn't mean you can detonate a D5 motor by just hitting it with a hammer. DoD has funded extensive research on the safety of high energy propellants, so they know exactly how to handle them.

If I were on a sub, I'd be more worried about the reactor than the D5.



You have to be careful with the generalization that 1.1 propellants are the only ones that are formulated with explosives. The split between 1.1 and 1.3 is relatively arbitrary based on a few specific tests. Some of the newer propellant formulations are blurring the line between the two by incorporating explosives into the mix to increase performance. I don't foresee a formulation come into play for 1.3 application that incorporates some of the more sensitive explosives (nitroglycerin, CL-20, etc.), but HMX and RDX have been used in 1.3 formulations.

Somewhat off topic, but maybe informative...

Offline Kabloona

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You have to be careful with the generalization that 1.1 propellants are the only ones that are formulated with explosives. The split between 1.1 and 1.3 is relatively arbitrary based on a few specific tests. Some of the newer propellant formulations are blurring the line between the two by incorporating explosives into the mix to increase performance. I don't foresee a formulation come into play for 1.3 application that incorporates some of the more sensitive explosives (nitroglycerin, CL-20, etc.), but HMX and RDX have been used in 1.3 formulations.

Somewhat off topic, but maybe informative...

True, I was simplifying for the sake of brevity.
« Last Edit: 03/12/2013 03:29 PM by Kabloona »

Offline strangequark

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Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

I'd also like to add that "detonable" is not the same thing as "sensitive".

Offline Kabloona

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Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

I'd also like to add that "detonable" is not the same thing as "sensitive".

Which is why D5's really don't mind hammers or nuclear reactors.  ;)

Anyhow, good luck strangequark to your Antares teammates on the 30XL test. Is there a target date yet? I didn't see one mentioned in Chris' article.
« Last Edit: 03/12/2013 06:53 PM by Kabloona »

Offline Calphor

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Wait, it's too detonable to be used for boosters, but apparently safe enough to put on a submarine next to a nuclear reactor?!?

I'd also like to add that "detonable" is not the same thing as "sensitive".

Which is why D5's really don't mind hammers or nuclear reactors.  ;)

Anyhow, good luck strangequark to your Antares teammates on the 30XL test. Is there a target date yet? I didn't see one mentioned in Chris' article.

I'm not sure if strange quark has a better estimate, but the last estimated test date I have heard was 27 March. I'm not sure how good that date is, so take it for what it is worth.

Offline simonbp

So, if the Navy is satisfied that using HMX is OK for SLBMs (and there haven't been any incidents, right?), then why isn't it used for launch vehicles? Especially for solid upper stages (like Castor 30) where the higher Isp would make a lot of difference.

Offline Kabloona

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So, if the Navy is satisfied that using HMX is OK for SLBMs (and there haven't been any incidents, right?), then why isn't it used for launch vehicles? Especially for solid upper stages (like Castor 30) where the higher Isp would make a lot of difference.

Your real question is "Why aren't Class 1.1 propellants used for launch vehicles, when so far they've been relatively safe in ICBMs?"  (it's a broader question than just propellants that use HMX).

The short answer is that launch vehicles are frequently and routinely launched in the vicinity of civilian populations and under the jurisdiction of civilian authorities like FAA whose job it is to make civilian flying objects as safe as possible. Such authorities have deemed Class 1.1 propellants too hazardous for civilian use. And even a Class 1.1 second stage could do considerable damage if, say, the FTS failed and the stage impacted a populated area.

Offline Calphor

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So, if the Navy is satisfied that using HMX is OK for SLBMs (and there haven't been any incidents, right?), then why isn't it used for launch vehicles? Especially for solid upper stages (like Castor 30) where the higher Isp would make a lot of difference.

Just for an idea of what we are discussing:

http://m.youtube.com/#/watch?v=SgvDkzy2bCM&desktop_uri=%2Fwatch%3Fv%3DSgvDkzy2bCM

That is the detonation of a C4 second stage. I don't know the propellant weight of that stage, but it is probably in the same ballpark as that of Castor 30A, if not somewhat smaller.
« Last Edit: 03/13/2013 02:47 PM by Calphor »

Offline Kabloona

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Calphor, nice find on that video. Good illustration that Class 1.1 propellant is basically a high explosive cleverly engineered to burn controllably enough for use as rocket propellant.

According to the blurb on YouTube, those stages contained about 18,000 lbs propellant. Which pretty nicely illustrates why no one wants 50,000 lbs (Castor 30XL) of Class 1.1 propellant flying NASA or commercial space missions.
« Last Edit: 03/13/2013 11:11 PM by Kabloona »

Offline Kabloona

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Is more thrust the primary reason?  (Military missiles being in a bigger hurry to get there than orbital launchers.) 

 - Ed Kyle

No, it's all about highest Isp for max performance (impulse) per unit mass, and the highest Isp solids are Class 1.1 because their ingredients are "high energy" to put it euphemistically. And as you know from the rocket equation, for a given payload, using a higher Isp propellant means the booster can be lighter and smaller, all other things being equal. And this is a priority for ICBMs that have to fit into silos and submarines.

If you have a copy of Rocket Propulsion Elements there's a graph of Isp versus burn rate for  a variety of solid propellant types, and the high energy Class 1.1 propellants are at the top of the graph, and you can see the Isp difference between a typical AP/Al/HTPB formulation (Class 1.3) and a Class 1.1 high energy formulation.

If you don't have a copy of the book it's available on Google Books. I'll see if I can find the graph and post it here.
« Last Edit: 03/14/2013 02:26 AM by Kabloona »

Offline PahTo

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Easy for you to say...
:)
Seriously though, excellent thread and information--thanks all for sharing your knowledge!

Offline Kabloona

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Is more thrust the primary reason?  (Military missiles being in a bigger hurry to get there than orbital launchers.) 

No, it's all about highest Isp for max performance (impulse) per unit mass, and the highest Isp solids are Class 1.1 because their ingredients are "high energy" to put it euphemistically. And as you know from the rocket equation, for a given payload, using a higher Isp propellant means the booster can be lighter and smaller, all other things being equal. And this is a priority for ICBMs that have to fit into silos and submarines.

I've seen references to a new miracle propellant called CL-20 that seems like a game-changer.  More energy but safer, etc..  But much harder to say: 
Hexanitrohexaazaisowurtzitane
[hexa-nitro-hexa-aza-iso-wurtzi-tane]

 - Ed Kyle

CL-20 could be a significant advance for military propellants if it can be stabilized long-term in propellant formulations, but again, that'll be a Class 1.1 propellant, so it'll never see use in launch vehicles.

Aside from its higher energy, it produces less of a smoke signature than HMX-based propellants, and reduced/minimum smoke propellants are especially attractive to Air Force and Navy for use in air-launched and ship-based missiles because low-visibility smoke trails mean it's harder for the enemy to see where the missile came from. So that's its most likely future application.

Offline baldusi

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CL-20 could be a significant advance for military propellants if it can be stabilized long-term in propellant formulations, but again, that'll be a Class 1.1 propellant, so it'll never see use in launch vehicles.

Aside from its higher energy, it produces less of a smoke signature than HMX-based propellants, and reduced/minimum smoke propellants are especially attractive to Air Force and Navy for use in air-launched and ship-based missiles because low-visibility smoke trails mean it's harder for the enemy to see where the missile came from. So that's its most likely future application.
Isn't the China Lake formulation limited by it's natural degradation rate?

Offline Kabloona

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Isn't the China Lake formulation limited by it's natural degradation rate?

I've been out of the industry for a while so am not up on all the details of CL-20, but that's why I added the caveat "if it can be stabilized long-term..."

But Long-term stability of propellant ingredients has been an ongoing issue in high-energy propellant chemistry, so there's plenty of history within the industry of learning how to stabilize tricky ingredients.

Offline kevin-rf

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Wouldn't a Class 1.1 Propellant simplify FTS?
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Offline Kabloona

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Wouldn't a Class 1.1 Propellant simplify FTS?

Kevin, did you watch that video posted above of the C4 stage being detonated? That was 18,000 lbs of propellant. Now imagine a 50,000 lb Castor 30XL being detonated via FTS 1000 feet above the pad due to a guidance system failure. Major damage to the pad and broken windows for miles around.

Offline kevin-rf

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Still, with that kind of termination, there is almost no chance of anything larger than a shred of confetti crashing into a civilian area ...

Yes, that was quite an interesting way to dispose of the stages. Are they using the same method for the first stages, or something less jarring, like burning them?
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Offline Kabloona

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Yes, that was quite an interesting way to dispose of the stages. Are they using the same method for the first stages, or something less jarring, like burning them?

Here's a nice hi-def video of a C4 stage 1 being disposed, apparently taken by the same guy who made the stage 2 disposal video that Calphor posted earlier:




I believe ATK has the contract for these disposals, and they're doing it way out in the Utah desert, so detonation is a quick and easy way to vaporize the stage. I doubt they'd burn them, as a caseful of burning propellant can still go propulsive even without a nozzle...and detonation means no large pieces of case left lying around...
« Last Edit: 03/14/2013 07:12 PM by Kabloona »

Offline Kabloona

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CL-20 could be a significant advance for military propellants if it can be stabilized long-term in propellant formulations, but again, that'll be a Class 1.1 propellant, so it'll never see use in launch vehicles.
This paper says there is a chance that propellant formulations using CL-20 have the potential to be Class 1.3.
https://docs.google.com/viewer?a=v&q=cache:CSWrlJkujGgJ:publications.drdo.gov.in/ojs/index.php/dsj/article/download/2158/1139+&hl=en&gl=us&pid=bl&srcid=ADGEEShlrLum9IA9koHKNeq34PE7qVdjzLy5bxzHWkiTD9Pp8fIbcqKDQvbt_JgSMdVA8lwhug5XCvCVJ_mxDa21P264bCHM1VJYd9ePo96FP0vpJ0mXveS_zD5Ad_db0MVI9MTZ8cGC&sig=AHIEtbT5oNI557sxHOHACAhwofTbl-P_NQ

ATK apparently makes the stuff, though only as a military grade.  There were stories about it being used for ABM R&D work I think.
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Ed, thanks for that reference, and I do stand/sit corrected that CL-20 propellants have attained Class 1.3 designation. Here's a more recent paper than the one you cited, with better detail about the propellant:

http://www.ijetae.com/files/Volume2Issue4/IJETAE_0412_102.pdf

However, it's worth noting that in the NOL card gap test, which is used to make the Class 1.1/Class 1.3 determination, the CL-20 propellant is a "58 card" Class 1.3, which means that it took a stack of 58 thin acetate cards between the test detonator and the propellant sample to prevent detonation. With a gap of less than 58 cards, the sample detonates. The dividing line between 1.1 and 1.3 is 70 cards. So the CL-20 formulation is only marginally Class 1.3.  Typically booster propellants are "zero card" Class 1.3, which means that even with zero gap between the detonator and propellant sample, the sample won't detonate.

So even though it's a Class 1.3 formulation, it's not a "zero card" Class 1.3  and thus probably wouldn't be looked upon favorably as a booster propellant.

There's also the cost factor. According to the article below, CL-20 runs $1300/kg in kg lots. Even if scaleup resulted in a tenfold cost reduction, $130/kg would still be two orders of magnitude more expensive than AP, which is dirt cheap to produce. And while the military has the $$ to afford CL-20 in smaller quantities for tactical missile and munitions applications, I don't see how it could ever be affordable in large quantities for booster applications.

http://www.gizmag.com/cl-20-high-power-military-explosive/24059/
« Last Edit: 03/15/2013 10:37 AM by Kabloona »

Offline kevin-rf

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I agree, most informative, Thank you

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Offline Kabloona

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Chris, can we keep him?

Only if you play nice.  ;)

Offline Kabloona

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Coincidentally, the solids for Pegasus were adapted from the Trident DII (D-5) sub-based ICBMs, for which compact design was even more essential. I don't recall off the top of my head, but those are likely submerged nozzle designs as well.
I've always thought that the Orion motor series was more closely related to the Small ICBM ("Midgetman") development effort, though they don't seem to be direct copies of anything in particular.  SICBM was 46 inches in diameter.  Trident D2 is 83 inches diameter.  The Orion 50 motors are 50.5 inches diameter.  What these all shared were innovative carbon carbon composite motor cases, along with high expansion ratio nozzles and advanced propellant formulations.



Correction and retraction:

 I stated earlier that the Pegasus (Orion) motors were derived from Trident II (D5) technology, based on what I now realize was a faulty memory bank. (I did once work on Pegasus, but it was a long time ago, and clearly my memory had an SEU on this issue.) In pondering that statement further, I realize it was incorrect, and that the correct derivation of Orion motors was from the strap-on graphite epoxy motors (GEMs) developed for the Delta II. Somehow I forgot that and then misremembered Trident II instead of Delta II...arghh...getting old...

Anyway, anyone who's interested can Google "atk propulsion product catalog" and see their whole lineup of motors and see the close correspondence between the GEM and Orion diameters...something I should have done before promulgating incorrect information. Apologies to all.

(You can also see from the catalog that the Orion motors use the same QDL-1 propellant formulation as the GEM-40, so I'm fairly confident that my "correction" here is, ummm, correct).
« Last Edit: 03/21/2013 01:41 PM by Kabloona »

Offline Calphor

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Coincidentally, the solids for Pegasus were adapted from the Trident DII (D-5) sub-based ICBMs, for which compact design was even more essential. I don't recall off the top of my head, but those are likely submerged nozzle designs as well.
I've always thought that the Orion motor series was more closely related to the Small ICBM ("Midgetman") development effort, though they don't seem to be direct copies of anything in particular.  SICBM was 46 inches in diameter.  Trident D2 is 83 inches diameter.  The Orion 50 motors are 50.5 inches diameter.  What these all shared were innovative carbon carbon composite motor cases, along with high expansion ratio nozzles and advanced propellant formulations.



Correction and retraction:

 I stated earlier that the Pegasus (Orion) motors were derived from Trident II (D5) technology, based on what I now realize was a faulty memory bank. (I did once work on Pegasus, but it was a long time ago, and clearly my memory had an SEU on this issue.) In pondering that statement further, I realize it was incorrect, and that the correct derivation of Orion motors was from the strap-on graphite epoxy motors (GEMs) developed for the Delta II. Somehow I forgot that and then misremembered Trident II instead of Delta II...arghh...getting old...

Anyway, anyone who's interested can Google "atk propulsion product catalog" and see their whole lineup of motors and see the close correspondence between the GEM and Orion diameters...something I should have done before promulgating incorrect information. Apologies to all.

(You can also see from the catalog that the Orion motors use the same QDL-1 propellant formulation as the GEM-40, so I'm fairly confident that my "correction" here is, ummm, correct).

Actually you were partially right. The Orion 32 is a direct derivative of the D5 third stage. In fact, it still retains part of the pocket in the forward dome where the aerospike resides on the D5 system. They use the 1.3 propellant instead of the D5 1.1 propellant to make handling easier. As for the Orion 50 motors, I do not know the full history of the series, but I believe that they were clean sheet for Orbital in support of the Pegasus program. I guess I'll have to do some digging to confirm.

Offline Kabloona

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As for the Orion 50 motors, I do not know the full history of the series, but I believe that they were clean sheet for Orbital in support of the Pegasus program. I guess I'll have to do some digging to confirm.

I guess it depends on how you define "clean sheet design." As you know, in the aerospace business it's a cost saver if you can base a new product on something you've already done. The motor diameters, lengths, etc were probably optimized for Pegasus, but Hercules already had the low-cost GEM case technology and propellant forumulation from the strap-ons they had already developed for Delta II, so they applied what they could from GEM to the Orion 50 series.

 Wouldn't hurt though to get confirmation from someone else, given my admittedly imperfect recollection. Antonio would confirm, I believe, if he could be induced to weigh in on such a minor detail.

Offline Jim

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The motor diameters, lengths, etc were probably optimized for Pegasus, but Hercules already had the low-cost GEM case technology and propellant forumulation from the strap-ons they had already developed for Delta II, so they applied what they could from GEM to the Orion 50 series.


Pegasus flew before the first GEM.

Offline Kabloona

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The motor diameters, lengths, etc were probably optimized for Pegasus, but Hercules already had the low-cost GEM case technology and propellant forumulation from the strap-ons they had already developed for Delta II, so they applied what they could from GEM to the Orion 50 series.


Pegasus flew before the first GEM.

Yes, by a few months, but I believe Hercules had already begun developing the GEM when they teamed with Orbital to develop the Orion 50 series, so they were able to leverage off what they had already begun doing with GEM.

Again, I could be wrong, but that's my recollection.

Edit: As for the when the GEM program actually started I don't know, but McDonnell Douglas won an R&D contract in mid-1986 to study Delta upgrades for MLV, and that could well have been when they began thinking of a follow-on to the Castor4A boosters. When they won MLV in early '87 that would certainly have provided the business case for going ahead with what became the GEM. So the GEM booster may well have been conceived as early as '86 and funded as early as the beginning of '87.

(Jim, sorry, I added previous paragraph on MLV while you were writing your post below on MLV...)

« Last Edit: 03/24/2013 02:48 AM by Kabloona »

Offline Jim

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Let's see
MLV contract was awarded 1987
I saw a inert Pegasus perform B-52 fitchecks in 8/89 at EAFB
I was at LAAFS until 8/88 when I moved to CCAFS, but before the move, I remember Dr Elias provide a briefing on the Pegasus concept

Not enough info to confirm or deny

Offline Kabloona

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I saw a inert Pegasus perform B-52 fitchecks in 8/89 at EAFB

Hah, I was then working at the Rocket Lab just up the hill...didn't get down to the flight line much, tho.

Offline Kabloona

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MLV contract was awarded 1987


Yes, MLV was awarded Jan 1987, and Orbital/Hercules partnership on Pegasus was announced June 1988.

So approx 17 month headstart for GEM, assuming GEM was awarded shortly after MLV.
« Last Edit: 03/24/2013 03:10 AM by Kabloona »

Offline Kabloona

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Well, I finally found the answer from Antonio himself. At 26:40 in this video he says the Pegasus motors were based on SICBM, not GEM as I had (mis)remembered.

GEM may also have derived from SICBM, since GEM and Pegasus began somewhat concurrently, had similar diameters, and used the same QDL-1 propellant.



I stand corrected once again and apologize for my faulty memory on the subject!

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Article that includes the reference to the CASTOR 30XL static fire and a screenshot from the dual view engineering video of the firing (L2):

http://www.nasaspaceflight.com/2013/04/orbitals-antares-eye-on-present-future/

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