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.
Is more thrust the primary reason? (Military missiles being in a bigger hurry to get there than orbital launchers.) - Ed Kyle
Quote from: Kabloona on 03/14/2013 01:05 amQuote from: edkyle99 on 03/14/2013 12:22 amIs 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
Quote from: edkyle99 on 03/14/2013 12:22 amIs 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.
Is more thrust the primary reason? (Military missiles being in a bigger hurry to get there than orbital launchers.)
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?
Wouldn't a Class 1.1 Propellant simplify FTS?
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?
Quote from: Kabloona on 03/14/2013 01:42 pmCL-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_NQATK 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
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.
Chris, can we keep him?
Quote from: Kabloona on 03/09/2013 02:08 pmCoincidentally, 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.
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.
Quote from: edkyle99 on 03/10/2013 12:47 amQuote from: Kabloona on 03/09/2013 02:08 pmCoincidentally, 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).
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.
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.