Author Topic: Ares I Development Thread  (Read 336866 times)

Offline clongton

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Re: Ares I Development Thread
« Reply #20 on: 08/24/2007 04:53 PM »
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rumble - 24/8/2007  12:32 PM

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clongton - 24/8/2007  8:53 AM

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gladiator1332 - 24/8/2007  9:20 AM

Don't get me wrong, the Ares I-X flight is going to be exciting, but I will have to agree with Jim on this one. The shape is there, but nothing else on Ares I-X will test the true flight article.

And MrTim, I do not think this qualifies as Ares I bashing. I am simply stating an opinion that Ares I-X is more of a political flight than an engineering flight. This doesn't make it any less exciting and is not meant in a derogatory way!
The only real concern I have with the Aes-1-X test flight is the interstage. I have heard that it will be much beefier than the flight article. I would hope that it would be much closer to the true mass and section, because this is an early opportunity to get some data on the suspected buckling the interstage may be subjected to. If itís going to fail, this would be the time to find out, while there is still reasonable schedule available to address it before it also commits to an Orion flight. If they substitute instead a beefier interstage, the flight would provide no data on this critical element. To me, this element is one of the most critical of all in the system design.

Can anyone address this concern I have?
Correct me if I'm wrong here:
Since the Ares 1-X flight will also be using a 4-seg SRB (plus a blank 5th segment), won't the max-Q pressure be lower?  

If they're flying a significantly stronger interstage on a vehicle that will experience reduced dynamic stresses, it sounds like to me they're just trying to avoid the embarrassment of having their new flagship crew launcher jack-knife on its first test.

I agree that the interstage should be as close to the current design of the flight article as possible.  ...weight & strength both...
Before we get too far afield, I think it is safe to say that the concensus thus far is that the interstage flown on Ares-I-X should approximate the flight article in mass and section. That's the only way to get good data on the potential for buckling. Can anyone offer information on just what NASA's plans actually are in this regard?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline simonbp

Re: Ares I Development Thread
« Reply #21 on: 08/24/2007 04:54 PM »
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rumble - 24/8/2007  9:32 AM

If they're flying a significantly stronger interstage on a vehicle that will experience reduced dynamic stresses, it sounds like to me they're just trying to avoid the embarrassment of having their new flagship crew launcher jack-knife on its first test.

Or, Ares 1-X is an aerodynamic test flight (like they keep saying), and Ares 1-Y is the structural test flight. But that makes too much sense, so it can't be right...  :bleh:

And yes, they do need an aerodynamic test flight because computer modeling of hypersonic flow is incredibly underdeveloped at this point, and the only existing hypersonic wind tunnels are tiny and from the 1960s. I would be far, far more worried if they put all their faith in a CFD simulation than actually attempting to do a flight test...

Simon ;)

Offline clongton

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Re: Ares I Development Thread
« Reply #22 on: 08/24/2007 05:19 PM »
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simonbp - 24/8/2007  12:54 PM

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rumble - 24/8/2007  9:32 AM

If they're flying a significantly stronger interstage on a vehicle that will experience reduced dynamic stresses, it sounds like to me they're just trying to avoid the embarrassment of having their new flagship crew launcher jack-knife on its first test.

Or, Ares 1-X is an aerodynamic test flight (like they keep saying), and Ares 1-Y is the structural test flight. But that makes too much sense, so it can't be right...  :bleh:

And yes, they do need an aerodynamic test flight because computer modeling of hypersonic flow is incredibly underdeveloped at this point, and the only existing hypersonic wind tunnels are tiny and from the 1960s. I would be far, far more worried if they put all their faith in a CFD simulation than actually attempting to do a flight test...

Simon ;)
Ok, that actually makes sense. If they are limiting the X flight to *just* aerodynamics, then it would make sense to beef up the interstage to well past known failure points so that it canít complicate the aerodynamics by buckling. This flight would then be followed by the Y flight, specifically to verify structural integrity. If thatís the case, then the interstage on the Y flight *needs* to be very close to the expected flight article.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline JIS

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Re: Ares I Development Thread
« Reply #23 on: 08/25/2007 07:42 AM »
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rumble - 24/8/2007  5:32 PM

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clongton - 24/8/2007  8:53 AM

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gladiator1332 - 24/8/2007  9:20 AM

Don't get me wrong, the Ares I-X flight is going to be exciting, but I will have to agree with Jim on this one. The shape is there, but nothing else on Ares I-X will test the true flight article.

And MrTim, I do not think this qualifies as Ares I bashing. I am simply stating an opinion that Ares I-X is more of a political flight than an engineering flight. This doesn't make it any less exciting and is not meant in a derogatory way!
The only real concern I have with the Aes-1-X test flight is the interstage. I have heard that it will be much beefier than the flight article. I would hope that it would be much closer to the true mass and section, because this is an early opportunity to get some data on the suspected buckling the interstage may be subjected to. If itís going to fail, this would be the time to find out, while there is still reasonable schedule available to address it before it also commits to an Orion flight. If they substitute instead a beefier interstage, the flight would provide no data on this critical element. To me, this element is one of the most critical of all in the system design.

Can anyone address this concern I have?
Correct me if I'm wrong here:
Since the Ares 1-X flight will also be using a 4-seg SRB (plus a blank 5th segment), won't the max-Q pressure be lower?  


Not if the GLOW is lower than Ares 1.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline rumble

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Re: Ares I Development Thread
« Reply #24 on: 08/25/2007 08:04 PM »
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JIS - 25/8/2007  2:42 AM

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rumble - 24/8/2007  5:32 PM

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clongton - 24/8/2007  8:53 AM

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gladiator1332 - 24/8/2007  9:20 AM

Don't get me wrong, the Ares I-X flight is going to be exciting, but I will have to agree with Jim on this one. The shape is there, but nothing else on Ares I-X will test the true flight article.

And MrTim, I do not think this qualifies as Ares I bashing. I am simply stating an opinion that Ares I-X is more of a political flight than an engineering flight. This doesn't make it any less exciting and is not meant in a derogatory way!
The only real concern I have with the Aes-1-X test flight is the interstage. I have heard that it will be much beefier than the flight article. I would hope that it would be much closer to the true mass and section, because this is an early opportunity to get some data on the suspected buckling the interstage may be subjected to. If itís going to fail, this would be the time to find out, while there is still reasonable schedule available to address it before it also commits to an Orion flight. If they substitute instead a beefier interstage, the flight would provide no data on this critical element. To me, this element is one of the most critical of all in the system design.

Can anyone address this concern I have?
Correct me if I'm wrong here:
Since the Ares 1-X flight will also be using a 4-seg SRB (plus a blank 5th segment), won't the max-Q pressure be lower?  


Not if the GLOW is lower than Ares 1.
I see what you're saying.  I realize that I've been working under the assumption that the original Ares I (the 4-seg + SSME version) had a lower T/W ratio on liftoff, which should translate to a lower max-Q figure.  The assumption is that the 5-seg Ares I's max-Q will be higher than the original 4-seg LV.  AND that the Ares I-X will more closely resemble the 4-seg Ares' dynamic pressure curve.

That's where that question came from.

Offline MrTim

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Re: Ares I Development Thread
« Reply #25 on: 08/26/2007 09:13 AM »
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gladiator1332 - 24/8/2007  6:20 AM

Don't get me wrong, the Ares I-X flight is going to be exciting, but I will have to agree with Jim on this one. The shape is there, but nothing else on Ares I-X will test the true flight article.

And MrTim, I do not think this qualifies as Ares I bashing. I am simply stating an opinion that Ares I-X is more of a political flight than an engineering flight. This doesn't make it any less exciting and is not meant in a derogatory way!

Well, I DID use the little winking emoticon... wasn't jumping on you TOO hard  :)
 ( was just hoping the thread really would manage to avoid becoming another "Mike Griffin is dumb/evil" or "Ares I is dumb and not gonna work" thread, but that seems to happen a LOT here, and since you started the thread I thought it funny you were so close to tempting fate there. )


Offline MrTim

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Re: Ares I Development Thread
« Reply #26 on: 08/26/2007 09:27 AM »
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clongton - 24/8/2007  10:19 AM
Ok, that actually makes sense. If they are limiting the X flight to *just* aerodynamics, then it would make sense to beef up the interstage to well past known failure points so that it canít complicate the aerodynamics by buckling. This flight would then be followed by the Y flight, specifically to verify structural integrity. If thatís the case, then the interstage on the Y flight *needs* to be very close to the expected flight article.

Chuck, as I and others have said before, this shot is about the aerodynamics, however, I would not be too surprised to see a few strain gauges placed at strategic locations. Even a beefed-up interstage would still yield good data, while being strong enough to not fail on the way up and cause a loss of the desired aero data. If all they get is the data they need to be sure the control systems will be adequate, that will be enough to justify the shot in my mind since it will make the second shot much more likely to succeed and yield its desired data etc. I would HOPE that the Y shot will get the first cut of a real interstage, and a test of the properly sized roll control system, among other things. I know some place a lot of confidence in CAD systems and computer models, but those things are just tools that need to be backed-up with real-world data. For a man-rated system, I'd like to see real data from actual rockets where possible, particularly with America's manned access to space on the line.


Offline JIS

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Re: Ares I Development Thread
« Reply #27 on: 08/27/2007 09:57 AM »
If Ares 1-X is to test aerodynamics, controll algorithm and 5seg SRB recovery it should have following properties:

1. Same outer shape
2. Same (or as close a s possible) liftoff T/W and flight profile
3. Same SRB burnout weight and CG
4. Same (or as close as possible) liftoff CG

Because there is less liftoff thrust the gross liftoff weight (GLOW) should be less.
This is achieved partly by the empty 5th SRB segment. Also the weight of US+Orion mock-up should be less to keep proper CG. This could be quite complex task to simulate. I wouldn't be surprised by requirement to place substantial ballast into the interstage which is the most aft segment which can actually hold it. (The test SRB+frustrum must be of the same empty weight as the real one).    

'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline JIS

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Re: Ares I Development Thread
« Reply #28 on: 08/27/2007 10:06 AM »
If the above is true there is no reason whatsoever to fly the real interstage on Ares 1-X as it wouldn't be subjected to the real loads. Also, the structure testing is be better on the test stand which can test performace under the extreme loads.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline wannamoonbase

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Re: Ares I Development Thread
« Reply #29 on: 08/29/2007 08:22 PM »
I find it interesting that EELVs are deemed unacceptable to be considered for the CLV yet Atlas V avionics will control the Ares 1-X.  

So either the Ares 1-X or position on the EELVs is wrong.  Which one is it?
Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline gladiator1332

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Re: Ares I Development Thread
« Reply #30 on: 08/29/2007 08:31 PM »
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wannamoonbase - 29/8/2007  4:22 PM

I find it interesting that EELVs are deemed unacceptable to be considered for the CLV yet Atlas V avionics will control the Ares 1-X.  

So either the Ares 1-X or position on the EELVs is wrong.  Which one is it?

It is a bit ironic, however, the Atlas V avionics are the only way Ares I-X can launch when NASA wants it to. And as was stated above, the main idea of Ares I-X is to see if the basic shape will work. It doesn't matter what avionics are on board.

Offline simonbp

Re: Ares I Development Thread
« Reply #31 on: 08/29/2007 10:24 PM »
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wannamoonbase - 29/8/2007  1:22 PM

I find it interesting that EELVs are deemed unacceptable to be considered for the CLV yet Atlas V avionics will control the Ares 1-X.  

So either the Ares 1-X or position on the EELVs is wrong.  Which one is it?

The Atlas V-based designs lost out to the SRB-based Ares I because it had a significantly lower overall safety rating (mainly because of the sheer number of engines that could go wrong, which I'm sure some Atlas person will dispute; c'est la guerre). That said, I don't recall and criticism of the Atlas III/V avionics system...

Simon ;)

Offline Jim

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Re: Ares I Development Thread
« Reply #32 on: 08/29/2007 11:19 PM »
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simonbp - 29/8/2007  6:24 PM
That said, I don't recall and criticism of the Atlas III/V avionics system...

Simon ;)

It is included, since it is not dual fault tolerant

Offline tnphysics

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Re: Ares I Development Thread
« Reply #33 on: 08/30/2007 12:02 AM »
In my opinion, Congress will cancel Ares I when the Falcon 9 Heavy comes along. NASA will be forced to buy F9 Heavies to launch the CEV.

Ares V will not be canceled.

Offline Jim

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Re: Ares I Development Thread
« Reply #34 on: 08/30/2007 12:30 AM »
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tnphysics - 29/8/2007  8:02 PM

In my opinion, Congress will cancel Ares I when the Falcon 9 Heavy comes along. NASA will be forced to buy F9 Heavies to launch the CEV.

Ares V will not be canceled.


Why?  That is ridiculous.  
Why not the Atlas V or Delta IV?  They already exist.  Congress is not going to show favoritism to Spacex and "force" NASA.

Ares V doesn't exist without Ares I

The F9 doesn't have the performance for the CEV.

Please think about the statement you made.

Offline clongton

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Re: Ares I Development Thread
« Reply #35 on: 08/30/2007 12:32 AM »
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tnphysics - 29/8/2007  8:02 PM

In my opinion, Congress will cancel Ares I when the Falcon 9 Heavy comes along. NASA will be forced to buy F9 Heavies to launch the CEV.

Ares V will not be canceled.
Huh? That makes no sense.
Without the Ares-I, the Ares-V cannot be afforded.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Online A_M_Swallow

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Re: Ares I Development Thread
« Reply #36 on: 08/30/2007 12:43 AM »
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clongton - 30/8/2007  1:32 AM

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tnphysics - 29/8/2007  8:02 PM

In my opinion, Congress will cancel Ares I when the Falcon 9 Heavy comes along. NASA will be forced to buy F9 Heavies to launch the CEV.

Ares V will not be canceled.
Huh? That makes no sense.
Without the Ares-I, the Ares-V cannot be afforded.

Without the Ares-I the Ares-V will have to reveal its true costs and time-scales.

Time for Direct to reappear.


NASA is in a race, it has to get to the ISS within 2 years of the Dragon.

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Offline tnphysics

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Re: Ares I Development Thread
« Reply #37 on: 08/30/2007 01:31 AM »
Agreed

Offline JIS

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Re: Ares I Development Thread
« Reply #38 on: 08/30/2007 08:31 AM »
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gladiator1332 - 29/8/2007  9:31 PM

Quote
wannamoonbase - 29/8/2007  4:22 PM

I find it interesting that EELVs are deemed unacceptable to be considered for the CLV yet Atlas V avionics will control the Ares 1-X.  

So either the Ares 1-X or position on the EELVs is wrong.  Which one is it?

It is a bit ironic, however, the Atlas V avionics are the only way Ares I-X can launch when NASA wants it to. And as was stated above, the main idea of Ares I-X is to see if the basic shape will work. It doesn't matter what avionics are on board.

Yes, as Ares 1-X is just testing SRB recovery, some flight algorithms, roll forces and aerodynamics there is no reason to use manrated avionics.
It is the same as with LAS testing.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline JIS

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Re: Ares I Development Thread
« Reply #39 on: 08/30/2007 09:25 AM »
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A_M_Swallow - 30/8/2007  1:43 AM

Without the Ares-I the Ares-V will have to reveal its true costs and time-scales.

Time for Direct to reappear.



Without Ares 1 the Ares V is just bigger (and more expensive) Direct. It was sold as a couple. As long as there is a lunar program both Ares1 and Ares V will be built.
'Old age and treachery will overcome youth and skill' - Old Greek experience

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