From wikipedia, the 4-segment SRB's consisted of ammonium perchlorate, aluminium, iron oxide, a polymer (such as PBAN or HTPB, serving as a binder that holds the mixture together and acting as secondary fuel), and an epoxy curing agent. This propellant is commonly referred to as Ammonium Perchlorate Composite Propellant, or APCP.

I know that the 5-seg is supposed to use a different mix, but I'm not sure how different. Nasty stuff though.

Fudge, in addition to cjsks's response, perhaps this link will provide you with some answers. http://en.wikipedia.org/wiki/Solid-fuel_rocket

cjsks,

Probably not that different a mix, more like a tweaking. The binder may be different though.

You are right about the nasty stuff bit though. Even hypergolics aren't that nasty (though they are nasty prior to use).

Usually ammonium perchlorate composite propellant (APCP) is used for most Solid fuel rocket motors I believe thats on the space shuttle, however higher performing solid rocket propellants are used in large strategic missiles (as opposed to commercial launch vehicles) with greater energy than ammonium perchlorate, NEPE-75 propellant used in the Trident II D-5 Fleet Ballistic Missile. But there are many other propellants such as black powder (not very useful except in fireworks), Zinc-sulfer (used in Esters ammature rocket motors), candy propellant (usually an oxidizer which is usually potassium nitrate and a sugar like dextrose, sorbitol, or sucrose), and a bunch others of which I don't know about because I don't deal with them in the model rocket hobby. The only reason the first too popped in my head is one is used by the old space shuttle booster rockets and the other stuck there from a walk through at a nuke museum. Either way most solid fuel rocket motors don't have the lift capabilities of liquid fuel or bi-propellant fuel rockets. However they are cheaper, and easier to construct. As well as safer and more reliable.

WOW. You all know your stuff. Thanks for all the answers and the link. Good stuff this.

spouting,

The use of NEPE-75 however has a much higher cost and its use is warranted in applications where that extra stored energy per mass and per volume is higher in priority in requirements than cost. It doesn't matter for the space shuttle for example because there is no inherent compact storage mechanism nor a need for the higher specific impulse (the SRB's are jettisoned just a couple of minutes into the flight.

Now I don't know if I would call them safer in the long run because solids can't be shut down. So while they are definitely less prone to failure, they are also much more difficult to control once lit, making survivability much less likely.

john

ATK's business is in making Solid rockets for the military, and all of their Business with NASA is specifically to increase the business so that costs can be lowered for the military (the minuteman rockets have enormous ATK involvement). Their business case would be for both, and the benefits would accrue to the Defense department.

There would be no justification for this business based on NASA's business alone.

Not sure about the second question, not really sure about the first either. But here is a link to an article about ATK's recent DM3 test. http://archive.feedblitz.com/632435/~4067969 Within the article they mention Ariane's contribution to plan, but it's not really the side by side comparison you're looking for.

mob

it is basically Ares I with the second stage replaced. Not sure why they didn't just continue on their own with the Ares I.

You must have been looking at the sea level thrust ratings (which is more about the bell design than the engine itself).

Both the Vulcain and the Vulcain 2 have higher vacuum thrust (1120 kN & 1340 kN respectively) compared to 1,033.100 kN for the J2-X.

The specific impulse (the true measure of how efficient a rocket engine is) is also greater for both Vulcain engines, however the difference isn't significant enough to really make much of a difference in my mind. The number of flights however would make a difference as the Vulcain is a tested engine whereas the J2-X is still going through testing.

The reason why I used the Vacuum ratings is because this is a second stage, not a first stage and that makes the Sea Level ratings not important at all because the engine won't be fired at this altitude.

The razor thin margins are more related to the SRB first stage. You can't just keep adding segments because the mass of the combined segments plus the payload (the second stage is payload) in this application needs to be less than the thrust level of the first stage thrust.

Hey Jonathan, just curious, where did you grab those numbers on the J-2X from? They may or may not be proven yet, but Wikipedia has vacuum thrust on J-2X at 1,310 kN and Isp at 448 sec. (vs 431 sec. on Vulcain 2). J-2X is listed at being roughly 700kg heavier though, so...

It may be closer than I was thinking. Thanks for the reply. Would be interesting to run the numbers...

I got them from wikipedia.

And oops sorry, those were J2 specs (notice my numbers from the top). so yeah, your numbers are correct. I looked at the other figures though, there isn't that much of a difference between the different engines either way. The Vulcain can be given a higher specific impulse by narrowing the throat but that would increase the chamber pressure, and that increases risk.

I don't think any of the engines would make that big of a difference. The use of the Vulcain is probably to bring in some VC (which is what my company is doing as well, going offshore to get VC money because there isn't enough investors with enough money here -- those trade deficits for the last 30 years is coming back to haunt us). The European company is also basically ESA, so the use of the Vulcain is basically a demand in exchange for the money.

I agree with cjsks; this system is vastly over-hyped. My prediction is that this design will make no economic sense in the end as ATK has been unable to make any substantial cost improvements in their 4 segment boosters over 30 years of operation. Now, with a new rocket, integration with a 2nd stage by a new partner, flying as a primary launch platform, and many other differences from their past use cases - coupled with a reduced flight rate without a guaranteed contract, this is going to be a set of huge hurdles for them to overcome. The next generation of launch vehicles places a great deal more emphasis on cost effective operations and this has never been the strong suite of their architecture. I don't think they had much choice but to gamble on this approach (they've pushed it for years and nobody but Griffin bit on it) as they would have eliminated themselves, but I give them very poor odds at being successful with this design. For their sake and increased competition, I really would love to be wrong, but this looks like a bad investment for ATK.

node.

Actually the reason why they haven't been able to make any real cost cutting efficiencies over the last 30 years is because really there are none to be made. The cost of the SRB's is pretty much in the fuel mixture 'cooking' process (there are videos of the process on the internet and they are actually quite interesting.

The Ares-1 costing issues was more based on the frequency of flight more than anything. The biggest concern that I personally have right now is that we will see too much capacity too quickly which would basically make the entire industry not viable.

As for the economics, ATK makes their money from selling solid rocket boosters to the Air Force. They are pretty much the only vendor for it in the US right now (yes a monopoly). This is basically the gravy. They don't need to financially justify this to anyone, all they really need to do is keep their influence with NASA (Constellation was very much a huge cash cow for ATK in that respect) and this does that without any cost to NASA (don't know if anyone noticed that but NASA isn't spending one cent on this).

Technically, the Ares I was a stretch, not because the rocket was a stretch, but they were reaching the limits of what the SRB could do as a stand alone rocket. Your total thrust needs to exceed your initial mass, otherwise you don't get off the ground. So if your payload (in the case of Ares I, Orion) starts to encounter mass creep and the payload mass starts to exceed the limits of the overall system, then you have to essentially throw it away. That is why Ares I ended up with a 'half' segment, because a full segment probably wouldn't have gotten off the ground.

ATK is free to pursue their business strategy as they and their stockholders see fit. My comment is that they are pursing a course that is going to get a limited amount of capital and time to succeed by their investors. They very likely might be exiting the launch vehicle business and be restricted to boost and niche applications.

I consider the SLS design to be the wrong rocket at the wrong time at the wrong price. The future of human spaceflight and space operations - commercial, private, or government - is all about the money. And if it's not about the money, it's still about the money -- these things need to be paid for. Even if SLS could be built under some NASA budget expansion (a fantasy, but let's go with it for sake of argument), there's no money for payload development. There are no commercial applications now or on any realistic roadmap that need it, so it's a one-trick pony; doing something nobody wants to see or can afford to buy a ticket for. I don't understand with low SLS flight rates how we radically improve operational costs or reliability.

Consider if you had a limited amount of capital to start a passenger airline with: would you require development of an extended version of the A380 with new engines and avionics that you flew once a month, or is a more appropriate model to lease a series 737's or A320's with existing engines that could be flown every hour? Of course, you can say, "Well, I can think of a situation where I need the new aircraft design" and you'd be right, but if you want to build an industry and get a lot of people to go a lot of places, I'd start with the smaller, more economical to operate for short hops systems. Let your route structure build, develop a market that then tells you what it needs and let them influence your follow-on architecture. I think we will have rockets bigger than the proposed SLS, but only when there are multiple uses for them and the business (not the political) case is made for them. The sooner we begin regular, reliable operations for business purposes to space, the sooner that day will come.

The SLS is the Spruce Goose of launch vehicles.

Well as I said, this isn't critical to ATK in terms of the solid booster business as their main business is in making rockets for the US Air Force. (Actually refurbishing them now is probably more accurate).

One of the justifications for Solid Rockets on SLS was specifically that it is necessary to lower the cost for their military business applications. (which goes to show how the lobbying system works).

ATK, even if this is being invested with shareholder money, is still doing this on the backs of the taxpayers through their military contracts.

And I completely agree that SLS is not the right direction right now. There is just no use for it right now. We need to define a use before we spend that kind of money.

According to financial data from mid-Q1, 2011; ATK's business segment breakdown was:

• Arrmanent Systems - 45% of total revenue / operating margin = 11.8%
• Mission Systems - 26% of total revenue / operating margin = 9.8%
• Space Systems - 29% of total revenue / operating margin = 10.0%

At that time, it was the world's largest manufacturer of bullets. Note that that is also it's highest margin segment. With their military contracts, they will be under increasing pressure with the DOD changes coming, to reduce costs -- interesting to see what that does to MIssion Systems.

18% of their sales were NASA and the STS contract was certainly a major stabalizing component. I don't think their new venture into the commercial launch business will offer the same margins initially - but we will see how things shake out.

node,

Actually sorry, the Thiokol division of ATK. ATK is a conglomerate that is a whole bunch of companies.

The space systems would largely be the Thiokol division. The armament systems would be their small weapons. They have bought up other companies that had mission systems functions.

To be completely accurate, it should state the thiokol division of ATK.

The JX2 is not tested? How is that considering it has already flown many many times?

THe only reason to switch to the Vulcan is that the Vulcan is currently being produced and the JX2 would need to return to production after a long time. They still have all the tooling but the Vulcan could be produced and a pretty good clip without much effort.

NASA doesn't want to pay for Liberty (unless it actually goes into service). ATK doesn't want to pay for the J-2X. ATK is partnering with EADS as an investment strategy. Pratt & Whitney Rocketdyne has no such interest apparently.

Sco

THe J2-X is not completely tested, however the J2 has been.

Well I think SLS is a really bad program. I would never build a rocket that has a worst case of one flight ever 2 years and a best case of 2 flights a year. And those figures are made up. Launching orion/MCPV on SLS is just plain stupid and is a made up payload that doesn't make financial sense. It would have made much much more financial sense to restart the shuttle supply chain. (if you look at the link on my profile relating to SLS, it throws some numbers on the estimated costs/fight rates).

I am very pro space, but not pro stupidity and SLS at the moment is most definitely stupidity.

As for this, I really don't care if ATK puts their own money into it. At least the deal with NASA does not involve money.

But is there more to the SLS that you think is stupid, or is it just the payload aspect? We need to be identifying solutions (as opposed to going around and around about the negatives). We know the negatives, now how can we use the reality of the situation to our advantage. You want SLS to have a purpose. Give it a purpose. What would you have it do that would let it fly more than say 10 missions a year? Using the hardware that is currently designed how would you change or modify the SLS program? We have all this technology at our disposal and we need to put it to good use. So how do we do that?

mob.

It is the justification aspect of it. The rocket itself is neither stupid nor smart. It is a rocket, it is neither. The wisdom of that rocket is based upon the uses for that rocket, and at this point, congress has only mandated that the rocket be built, not that there actually be a need for that rocket. The rocket is being built because ATK has power in the halls of congress and push hard. But until there is a payload that needs this rocket, you are either going to have it sit on the shelf doing nothing (wasting more and more money because you need to keep the people trained) or you are going to be putting payloads on it that don't need the rocket (Orion, which was never intended to fly on Ares V), thereby wasting money on an infrastructure that can't justify its existence.

Now if there were a series of payloads that can be identified, go for it, but right now it is all 'prepare ourselves for a manned mission to the moon' without a program for a manned mission to the moon.

Now, something like the rocket engine. Lets build a rocket that uses the engine, in a single unit, that way those costs can be amortized into the development of a future rocket that would match SLS's capability. But that rocket would not be built until it was needed.

As for a use. Well I can think of one right now. A new space station that has crew modules that are MUCH larger than the existing modules that had to fit in the cargo bay of the space shuttle. But ISS is complete and no new station is in the works.

I do not believe the SLS is a bad program, just horribly mismanaged. Lets face it, it is Ares 5 after government meddeling. We do need heavy lift, that is a fact. Is heavy lift needed for comercial reasons? rarely.

If we want to launch Hubble and Space station sized loads, we need something like it. Manned missions need it too, but not for the capsule, that is just silly.

The original plan was to revert to the original Satrun I/V scheme where Satrun 1 would launch the capsule, and Saturn V would launch the rest and a docking would ensue.

Same for Ares 1 and V. no coincidence there.

To launch a capsule on a 100 ton rocket is reaching for a use though.

As for this rocket, why do we need another rocket system of this size?

We already have 2 the Delta ann Atlas with another one recently put in mothballs, Titan.

if the SLS is needed, then exactly what programs that are currently in development that NEED it (And I mean need as something that absolutely need that rocket). The answer is, there ARE none.

and it isn't horribly mismanaged because it hasn't gone past the conceptual stage yet. It is still in the concept stage. The problem is that Congress really doesn't want to give NASA the money to build it, yet they are demanding that NASA built it.

How exactly is that horrible mismanagement?

it is orion.

Oh, I know it can be. But that doesn't pretend to be a 'commercial' manned vehicle.

If NASA's ends up as the only customer...well, it's effectively Ares-I

Well it isn't so much a contract rather than an agreement. Basically it is a commitment on the part of NASA to use this if it works. Essentially it is ATK finishing Ares I on its own.