Author Topic: CASTOR 30XL prepares for static fire ahead of providing Antares boost  (Read 27812 times)

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.
https://www.fbo.gov/index?s=opportunity&mode=form&id=048e8c26275ed38540513fdea33a66e2&tab=core&_cview=0

 - Ed Kyle

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

Chris, can we keep him?
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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.

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