Gaetanomorano, nobody is going to take you or your website seriously if you insist on using BIG BOLD CAPITAL LETTERS, colored italicized words, and excessive highlighting. Your website is like a SPACE TABLOID. Total in-your-face formatting overload.

*underlining substitutes highlighting

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You can't really tell the difference between drunken rambling and sober blogging.

Please define failures in both your cases.
We have had no catastrophic failure of the solid booster itself, although the booster failure caused a catastrophic failure of the liquid tank.
From what I remember, the solids still seemed to be running.

On the same token, how many liquid engine shutdowns have there been. I recall at least one during the Apollo flights. So; although not catastrophic, and planned redundancy saved it, it was still a failure.

There also wasn't sophisticated computer modelling, high tech quality control techniques or such high technological tolerances in the manufacturing at the time either. I wonder what Von Braun would think of solids in today's environment.

That could be a factor, but I do see solid components of any proposed architecture. So, shaking may still be an issue, although buffered by some degreee.

I saw interviews of Apollo astronauts talk about the violent shaking of the SatV, but after first stage separation it was smooth sailing.

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Say what? Liquid fueled engines have failed many times in manned launchers. Not catastrophically (I'm not counting the catastrophic N1 failures, because they happened to not have men in them. But face it: catastrophic liquid fuel engines caused the Russians to not reach the moon), but they certainly have failed a lot. How many solid fueled engines have failed on the more than 200 flown? 1. And that was because it was launched beyond its weather envelope, and afterwards a design change was made.

How many of the astronauts that have flown the shuttle didn't like its SRB's?

Yes, but now you're suddenly making a general rant against SRB's into a particular case where there is a design issue yet to be solved. That's not how you started.

And I've heard accounts of astronauts saying that getting launched in the shuttle was a sunday afternoon ride with their grandma compared to earlier launchers. So that ain't saying a lot. Ares 1 is different as it uses only one SRB, that's true. But again, that was not the argument you started with.

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Good point. Ignoring the design change that solved the issue, a Challenger incident would more than likely not have crippled an Ares 1. I don't know whether it would have reached orbit (I can imagine the leak causing decreased performance, but I'm not sure about that), but at least it would have gone smooth and allow for a clean capsule separation with the escape system.

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During climbout, the Challenger SSMEs were gimballing pretty heavily to correct the thrust from the leak. It's unknown at this time if the thrust vectoring ability of the Ares I configuration would be sufficient to counter a segment leak. Following the redesign, such a leak is much less likely. Prior to Challenger, there was evidence of leaks on a few Shuttle flights. Apparently, none of them were directed at the ET.

As for liquid engine shut downs, there were a few second stage engine failures during the Apollo era (Apollo 13 immediately comes to mind and that may not have been the only one). There were a few Shuttle SSME shutdowns as well. All of the vehicles made it to orbit. That's why you build redundancy into a design.

I'm specifically talking about the robustness of the liquid fueled engines where if they fail they can be shut down. Note in those cases where they had to be shut down in manned missions they did NOT cause catastrophic loss of mission.
For me if a failure of an engine solid or liquid is the direct cause of catastrophic mission loss, well then that is a catastrophic failure on the part of that engine.
You brought up failures of unmanned liquid fueled engines but of course there have been many failures of unmanned solid rocket engines! That's one of the main reasons rocket scientists such as von Braun had a distrust of them for manned flight.
This Wikipedia page gives the failure rate of solids as 1 in 100 and notes they usually involve immediate and catastrophic mission loss:

Solid rocket booster.
http://en.wikipedia.org/wiki/Solid_rocket_booster

That catastrophic loss of the Challenger mission took about a minute after the solid rocket booster failed is hardly reassuring.


Bob Clark

The Ares solids have the inherent dangers of all solid rockets AND on top of that because they are the only propulsion for the first stage their higher than normal shaking can also cause catastrophic mission failure.


Bob Clark

My main problem with SRB's are the externalized environmental costs associated with them. Perchlorates are nasty stuff. SRB's are acceptable now only because they are so rarely used. If space travel ever gets as routine as we would like, SRB's would have to be outlawed. Better to get used to using LOX and wind generated LH2 now, because in the future, that's all that's going to be allowed.

Nice of you to have changed the discussion of this thread.
Shame on me for having got suckered into the SRB discussion.

How about we get back to the subject at hand? How does Direct differ from Ares V ?

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You ignore the N1 failures of the engine's turbopumps, which caused catastrophic failure of the vehicle. Not surprisingly, when these turbopumps decide to blow to pieces at 30000 rpm.

There's also the risks involved in the fuel itself. A Soyuz failed catastrophically when its liquid fuel ignited on the pad.

You ignore the fact that the SRB's continued to work after the liquid fuel part of the craft blew to pieces.

Let's play it fair. If you're only counting manned missions for liquids, do the same for solids. So that leaves only the shuttle SRB, with a failure rate of less than 1 in 200, and no failures whatsoever since the redesign after Challenger. And on top of that, as said, even in the Challenger accident the SRB's continued to work. They were the cause of the accident, but only the rest of the stack (liquid fueled) failed because of it.

A liquids-only craft has all the inherent dangers of a liquid fueled rocket AND on top of that because there are multiple engines, a multiplication of catastrophic failure modes (turbopump explosions to name one).

The shaking of a single SRB is taken into account in the design of Ares1.

It's normal when defending an idea to use the arguments to support the idea, but imo you haven't shown there really is a disadvantage in using an srb as first stage.

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That's a completely different argument, and a valid one.

How environmentally friendly is the creation and storage of LOX and LH2 at the moment?

And how environmentally friendly is the burning of them in a rocket in reality (including all (by)products of combustion that occur in reality)

I'm not trying to bash the argument through fake questions, I'm seriously asking because I don't know these details.

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Ares V uses 2 SRB's, so that makes the derailed discussion twice as on topic!

Allrighty then, on topic.

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Still worse than manned liquid fueled engine caused catastrophic losses: 0%.



Bob Clark

?????

Read this article in its entirety:

Is NASA's Project Ares Doomed?
Published on 10-26-2008
http://www.roguegovernment.com/news.php?id=12535

The extreme shaking problem is specifically because it is a solid rocket booster that is providing all the thrust at the first stage.


Bob Clark

I am aware of the problem. So are the designers. They're looking how to make the thing work.

Do you really think that it is uncommon for a craft to encounter issues like these during the design phase?

The design phase is when the thing doesn't work yet. The design phase is finished when it works. Don't fall off your chair because Ares 1 has a problem to be overcome during design. If it hadn't, you wouldn't need a design phase. You'd just wake up with the idea, go to the workshop, bolt the thing together and fly the baby. It doesn't work that way.

Had you designed a craft using liquid fueled engines, you would also have gotten into problems along the road. And you'd solved them, unless they truly were so-called showstoppers. Likely there wouldn't have been mass hysteria about it, because the novelty factor would be lower and therefore it wouldn't be as superficially interesting.

Wait & see until the final design of Ares 1 is there and how it performs. Only then you can evaluate how good a craft it is. It's unfare to cry doom over problems before they've finished solving them.

It's like letting an architect design the foundation of your house, and then when he encounters a weak spot in the bottom call the thing off before he even had time to grad a calculator and come with a suitable solution for the problem. If on the other hand the house is built and still collapses, than it was a badly designed foundation indeed. If the architect tried his best but couldnt find a theoretically OK foundation, then the current technique wasn't suitable indeed. But before he's finished his design phase, you can't yet say that.

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Your math is faulty; that exploding Soyuz was manned. The crew was saved by the launch escape system.

If you're limiting the definition of "catastrophic" to failures that caused the loss of mission, vehicle, and crew, then you're unfairly targeting the shuttle. It may be the first manned spacecraft (in service) to use large solid motors, but, more importantly, it's also only the second manned spacecraft to lack an adequate LES (the first was Voskhod). This won't be the case for Ares. A Challenger-type joint failure, even if it caused a loss of control, would be survivable because of the LES. Even a destructive case rupture (like the 1993 Titan 4 or 1997 Delta II failures) would likely be survivable.

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Internal turbinators differentiated in size by prime factors.

I thought we had this discussion?

It's the harmonic reinforcement which causes most of the grief, just like the Tacoma Narrows bridge. So, just avoid harmonics. Primes aren't harmonic.

Do said primes include 1? And if so, do they include 0.999... for infinite 9's? Shall we retype everything ever put on BAUT?

but yeah, I agree that there likely is a way to design away from the problem. It may come at a mass penalty (to change the eigenfrequencies), but what is considered a "system" and what is considered a "mass penalty" eh. Is a turbopump a system or a mass penalty? A solid rocket doesn't need one, a liquid one needs one to make it work. So...

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http://vimeo.com/5339573

Just to prove a point, Direct 3.0's own presentation shows the 1978 initial heritage of the Shuttle Derived Inline LV.

Huh? That seems like a very loose connection to me.

Direct vs Ares-5... Both have SRB's. I don't see how solid vs liquid applies.
Maybe the choice of putting the capsule on Direct instead of the 1.5 architecture... Both have SRB's. I don't see how solid vs liquid applies.

The only reason I care though, is that I was hoping to hear the major and minor differences between Direct and Ares-5.

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No, I'm allowing catastrophic mission failure to include cases where the crew manages to survive. I hadn't heard of this case before:

Soyuz launch escape system.
http://suzymchale.com/kosmonavtka/soyescape.html

This is rather a gray area since this happened on the launch pad before the engines had even fired. However it was due to a liquid fuel leak so could be said to be due to liquid fueled systems in general.


Bob Clark

You may or may not have noticed an emoticon depicting a growing nose. I used it to imply "not so correct reasoning". ANd I think you misinterpreted my second line.

SRB vs liquids has little to do here indeed, since both Direct and AresV use SRB's. So, on to the differences between both was what I meant with "allrighty then, [let's get] on topic".

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Engineers have been designing out harmonics in high-performance turbines for years so they don't self-destruct. They don't use primes (except for the number of turbine blades - sometimes), but they do use variable-geometry inlets and outlets. Straight shots tend to have resonant problems at certain turbine frequencies.

Ah; humor. What a concept. Actually; I don't see much use of that emoticon, so it seemed to have slipped in context for me. Thanks for clearing that up.

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It's being used in all kinds of places. Some speakers are designed specifically not as a box to reduce harmonics.

Agreed, unless you're Spinal Tap, a speaker can't be compared to an SRB. But the principle remains: there are known ways to design yourself out of vibration trouble, so there's a good chance it'll work for Ares 1 too. Which is off topic, but anyway.

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humm.. i humbly disagree. a speaker and an SRB have a lot in common. both are open ended objects that have shock waves exiting the opening at specific wavelengths.
the harmonics of the SRB are quite similar to a tubular loudspeaker, and the mathematics for both are the same. Now apart from spinal tap i cant think of many bands wanting one of those SRB's for their bass. well.. mabe Dimmu borgir.. that lead singer do kinda sound like a big rocket sometimes

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Signature? Why?

On top of that, it saves on on-stage fireworks costs considerably.

SRB: Solid Rocking Band.

ahem, on topic maybe?

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SRB's velocity flows are beyond MACH, so "shock wave" is technically correct.

A speaker's velocity flows are well under MACH, so "shock wave" is incorrect. "Sound wave" is correct.

They are most certainly not the same!

Here's an online loudspeaker graphic calculator. Here's a collection of many more, most of which show the math. This $248 book entitled, Theory & Design of Loudspeaker Enclosures is chock full of math. In fact, unless you're either a mathematician, a physicist, or an aero engineer, you probably won't understand much of it.

Here's a web page showing the mathematics typically used in loudspeaker Transmission Line, that is, a driver in a tube, the closest parallel between a speaker and an SRB.

Please show me the online SRB calculator, or the mathematics used in SRB design.

Thank you.

Subsonic/supersonic makes the required set of formulae different.

This would drag us back to the likes of the discussion of Bernouilli and lift. Don't make me link That One Post again.

And it's not really on topic.

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