Author Topic: DIRECT v3.0 - Thread 1  (Read 863393 times)

Offline TrueBlueWitt

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Re: DIRECT v3.0 - Thread 1
« Reply #40 on: 06/01/2009 05:29 PM »
I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?

Forgive me if this is a non-issue, as I am not too good with the rocket science side of these things.

Non-Issue.. Far less offset than current shuttle stack..  Plenty of gimbal range for SSME's to keep Jupiter tracking as required. Small payload penalty for offest thrust.

Speaking of which.. 
Ross... any further word on dropping vectoring control on SRB nozzles?

Offline John Duncan

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Re: DIRECT v3.0 - Thread 1
« Reply #41 on: 06/01/2009 05:30 PM »
I hope that the new pdf will have some good, large dimensioned drawings of each version of 3.0 for us modelmakers.  I have watched the after skirt/thrust structure of the core change quite a bit over the span of time.

Phenomenal job done by all!  It will be difficult to see the concept being ignored by the commision now, unless the fix is already in AGAIN.

Hopefully not.

« Last Edit: 06/01/2009 05:32 PM by John Duncan »
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Offline Harlan

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Re: DIRECT v3.0 - Thread 1
« Reply #42 on: 06/01/2009 05:33 PM »
I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?

Non-Issue.. Far less offset than current shuttle stack..  Plenty of gimbal range for SSME's to keep Jupiter tracking as required. Small payload penalty for offest thrust.

Sure, but does it affect failure modes? I can imagine that a loss of one of the two paired engines would still allow a controllable stack for AOA or ATO (depending on timing), but if you lose that single engine, with all thrust now off-axis, do you have to shut everything down and fire the CES?

(ps - very nice graphics!)

Offline gladiator1332

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Re: DIRECT v3.0 - Thread 1
« Reply #43 on: 06/01/2009 05:35 PM »
I hope that the new pdf will have some good, large dimensioned drawings of each version of 3.0 for us modelmakers.  I have watched the after skirt/thrust structure of the core change quite a bit over the span of time.


It would be nice to some day have a "Direct Evolution" image, similar to the Stick Evolution on here. It would be interesting to see how the baseline vehicles have evolved over the span of all this. I'm sure with all of the baseball cards it would be quite easy.
But right now I'm sure the Direct Team has a lot more to worry about, let the history books be written after.
« Last Edit: 06/01/2009 05:35 PM by gladiator1332 »

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Re: DIRECT v3.0 - Thread 1
« Reply #44 on: 06/01/2009 05:38 PM »
The Fwd Skirt actually comes in along with the 'foam' which covers the rest of the LOX tank.   Its just a visual thing.   They could be separated, but we wanted to keep the video short.

Ross.


Do you still need the foam now that the orbiter is gone?  How much does the foam weigh?  I would think the SRBs can take the impact of shedding ice.  How about the Delta IV Heavy?  Does it shed a bunch of ice on itself on ascent?  I have seen some video of Saturn V launches and huge chucks of ice are coming off.

Danny Deger

The foam on the ET is the mehtod of insulating the tank from the ambient temperature.  Wtihout it the boil-off would be huge and given the tank is loaded about 12 hours prior to flight (could be less with a Jupiter-like vehicle but still significant time prior to T-0) you need some method of insulation. 
Enjoying viewing the forum a little better now by filtering certain users.

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #45 on: 06/01/2009 05:48 PM »
The Fwd Skirt actually comes in along with the 'foam' which covers the rest of the LOX tank.   Its just a visual thing.   They could be separated, but we wanted to keep the video short.

Ross.

Thanks, I knew I'd catch your attention !
But this is confusing... "comes in along with the 'foam' " ? What exactly comes in along ?

Its done that way purely for the purposes of keeping the animation sequence 'simple' and 'short'.

Furgedaboudit :)

Seriously though, the animation shows the LOX tank as one part, and then just to save time, "everything else" (foam covering, Fwd Skirt, Payload Interface etc. all come into the picture at the same time.   Obviously that isn't how manufacturing actually takes place!   LOL


Quote
Jupiter's forward skirt is build of what ?

Primary structural material for the panels is Al 2219.   There are some parts made from Al-Li 2090 too.   Essentially it will be somewhat similar to the current Interstage.   The Fwd Skirt area would also integrate the fittings for the upper Core Stage umbilical connections as well as the GOX re-pressurization lines and electrical cable tray too.

There's a fair bit of 'stuff' going on up there :)


Quote
TIA again, (hope I'm not abusing your patience).

Not at all :)

Ross.
« Last Edit: 06/01/2009 05:51 PM by kraisee »
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Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #46 on: 06/01/2009 06:00 PM »

Do you still need the foam now that the orbiter is gone?

Oh yes.   Deffinately.   You don't want chunks of ice falling down onto anything below.   Think about an ice collision with one of the Aft SRB Booster Separation Motors, or perhaps a large chunk of ice hitting the Aft SRB mountings?   Anything like that would make for a pretty bad day.


Quote
How much does the foam weigh?

TPS & TCS together mass ~1,884kg.

An ice layer would mass an awful lot more than that and you would carry quite a lot of it all the way up to some pretty high altitudes, so your performance would hurt.


Quote
I would think the SRBs can take the impact of shedding ice.

The flight immediately before STS-107 had a chunk of foam hit an SRB Aft Skirt.   It left a visually noticeable dent in the thick steel structure.

Simple rule:   You don't want anything falling of and hitting anything else.


Quote
How about the Delta IV Heavy?  Does it shed a bunch of ice on itself on ascent?  I have seen some video of Saturn V launches and huge chucks of ice are coming off.

Don't think Delta does because it uses foam the same way as Shuttle.   But Atlas has a thin layer build up on its LOX tank (higher temp than LH2 tank).   Most of it is shed before Max-Q.   It is designed to handle it.

Ross.
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Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #47 on: 06/01/2009 06:12 PM »
Copied from V2.0 thread, since it appears to be just as relevant to DIRECT 3.0...


And no, the LOX tank is sized to precisely the same capacity as the current ET's Ogive tank.

We do still have an option to increase the capacity of both the LOX and LH2 tanks by ~7-9% (in the same way as NLS was going to), but right now, mostly for simplicity sake, we have simply chosen not to mess around with altering the capacities.   We can close all performance requirements comfortably without it.


Not heard of that 7-9% stretch option before.

I'd suspect this is because the relationship of SRB-to-ET-to-Shuttle results in more space under the ET for engines than DIRECT actually needs?

Shrink the engine space and extend the H2 tank downwards?

Correct.


Quote
It recently occured to me to wonder how there is space under the "ET" to fit a bunch of engines at all. Shuttle's ET is sized to fit between the SRB's (and presumably not to extend too far down into the base heating zone). Nothing about the shuttle "demands" that this should leave enough space under the ET for a set of engines.

There is also the issue of having to pump LH2 "upwards" into the Shuttle's belly.   The bottom of the LH2 tank can't be very far below that point or your flow would run into some fairly significant problems.


Quote
That also raised another question. DIRECT's H2 tank height (bottom of barrel section to thrust beam) is defined by the distance between the lower & upper SRB attach points.

Not always.   You can actually relocate the attach point from the Fwd Skirt area of the SRB to the bottom of the Upper SRB Segment.   That technique is how the Shuttle Program intended to upgrade to 5-seg SRB's without changing the size of the ET.   Precisely the same technique could be done for Jupiter too.


Quote
Adding another segment to the SRB also requires the same H2 barrel stretch. I'd always assumed this was a 25% increase in core fuel, but now that doesn't seem right.

How much does the core fuel load increase for the heavy config?

You are correct that 25% is not the right figure.   A full 'segment' is 320" long.   The LH2 barrel would have to stretch by that much.   The LOX tank would need a similar capacity increase too.   Together they would increase gross propellant capacity by about 278,826kg.

Ross.
« Last Edit: 06/01/2009 06:13 PM by kraisee »
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Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #48 on: 06/01/2009 06:21 PM »
I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?

Forgive me if this is a non-issue, as I am not too good with the rocket science side of these things.

Slight gimballing of one or more of the engines with provide the correction for the offset.

Its the exact same technique you'd have to use in the event of an engine-out situation.   So the capability would have to be developed into the avionics suite anyway -- as such, it's not an "additional" concern.

Our Marshall guys have already analyzed this in a fair bit of detail.   It turns out that if just one engine applies the counter-thrust, it would lose less than 1% of its performance, so the effect is essentially in the realm of 'noise'.

Ross.
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Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #49 on: 06/01/2009 06:26 PM »
I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?

Non-Issue.. Far less offset than current shuttle stack..  Plenty of gimbal range for SSME's to keep Jupiter tracking as required. Small payload penalty for offest thrust.

Sure, but does it affect failure modes? I can imagine that a loss of one of the two paired engines would still allow a controllable stack for AOA or ATO (depending on timing), but if you lose that single engine, with all thrust now off-axis, do you have to shut everything down and fire the CES?

(ps - very nice graphics!)

That all depends on the exact timing of the event.   If it happens early enough in the flight, while still in the thick atmosphere, then the need for a high Angle of Attack in the airflow would necessitate an abort, but that early in the flight, if you lose an engine the mission will be an LOM anyway.

Once out of the atmospheric effects, the Core and PLF structure is designed to handle a maximum AOA offset cause by such worst-case engine-out situations.

Ross.
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Offline jarmumd

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Re: DIRECT v3.0 - Thread 1
« Reply #50 on: 06/01/2009 06:31 PM »
Ross,
   Looking at the detailed pictures of D3, it looks like you (team) are dropping the current ESM panel attachment method for LSC or frangible joints up at the Orion/SM.  If you change the panel attachment method (6 connections, 2 per panel), that will change the load path into the Orion drastically.  And not having anything under the SM puts the SM in tension instead of compression like it is in Ares I.  Changing the load path into the Orion/SM carries a time & money penalty for redesigning them.  Is this something you have considered either via schedule & cost or via panel/faring redesign?  I thought I remember it being stated that the most recent Orion version would be "held" and adapted to Direct.

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #51 on: 06/01/2009 06:34 PM »
Ross... any further word on dropping vectoring control on SRB nozzles?

It seems to be a viable option which would reduce the per-flight costs by a reasonable amount and which would also improve both LOM and LOC too.

Its an option which really needs further detailed trade study after the Jupiter's have been selected though.   We aren't going to pursue it at this time, mostly because we don't have sufficient resources to do it comprehensively and because we have other priorities with the Augustine commission just around the corner.

Ross.
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Offline Ben the Space Brit

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Re: DIRECT v3.0 - Thread 1
« Reply #52 on: 06/01/2009 06:53 PM »
And what is it going to carry other than garbage?  If it can't come down like the shuttle, then it is useless for science or return hardware.  Access and loads are bad.

To me, Jim, that is mainly an engineering issue.  Okay, a complex and likely very expensive engineering issue but just that nonetheless.  I'll let those who know more about shock absorbers and force mitigation to decide exactly how we are going to get old EXPRESS pallets, experimental results and the like down in one piece.
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Offline TrueBlueWitt

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Re: DIRECT v3.0 - Thread 1
« Reply #53 on: 06/01/2009 07:11 PM »
Ross... any further word on dropping vectoring control on SRB nozzles?

It seems to be a viable option which would reduce the per-flight costs by a reasonable amount and which would also improve both LOM and LOC too.

Its an option which really needs further detailed trade study after the Jupiter's have been selected though.   We aren't going to pursue it at this time, mostly because we don't have sufficient resources to do it comprehensively and because we have other priorities with the Augustine commission just around the corner.

Ross.

Seems this would significantly simplify fight software control logic and also reduce some integration work.. and as you say, one less thing that could fail and cause an LOM or LOC.

Offline renclod

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Re: DIRECT v3.0 - Thread 1
« Reply #54 on: 06/01/2009 07:25 PM »
...
Speaking of which.. 
Ross... any further word on dropping vectoring control on SRB nozzles?

Hey ! Fixed nozzle SRBs were considered by MSFC as of last year (to my knowledge) in the context of Ares V. Now, compare the [roll] control authority of 6 RS-68 @ 10m v. 3 SSME @ 8.4m (roughly; and even with the 4seg to 5 or 5.5 seg difference). Eh ? Let's give Caesar what is Caesar's.

« Last Edit: 06/01/2009 07:27 PM by renclod »

Offline TrueBlueWitt

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Re: DIRECT v3.0 - Thread 1
« Reply #55 on: 06/01/2009 07:57 PM »
...
Speaking of which.. 
Ross... any further word on dropping vectoring control on SRB nozzles?

Hey ! Fixed nozzle SRBs were considered by MSFC as of last year (to my knowledge) in the context of Ares V. Now, compare the [roll] control authority of 6 RS-68 @ 10m v. 3 SSME @ 8.4m (roughly; and even with the 4seg to 5 or 5.5 seg difference). Eh ? Let's give Caesar what is Caesar's.



I found reference that suggests SSMEs can gimbal plus or minus 10.5 degrees..

What are the max Gimbal angles for an RS-68?

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #56 on: 06/01/2009 08:03 PM »
Ross,
   Looking at the detailed pictures of D3, it looks like you (team) are dropping the current ESM panel attachment method for LSC or frangible joints up at the Orion/SM.  If you change the panel attachment method (6 connections, 2 per panel), that will change the load path into the Orion drastically.  And not having anything under the SM puts the SM in tension instead of compression like it is in Ares I.  Changing the load path into the Orion/SM carries a time & money penalty for redesigning them.  Is this something you have considered either via schedule & cost or via panel/faring redesign?  I thought I remember it being stated that the most recent Orion version would be "held" and adapted to Direct.

We have some Orion engineers who have spent quite a lot of time analyzing this precise issue.

The attachment points aren't that much of a concern, because a mounting ring would support the Orion using the same points as at present on the 'wide' part of the SM.   As you say, there might possibly be a need for some slight re-design of the SM, but the structure right now appears to meet all of the different expected loads of a J-130 and J-246 flight already, without breaking the 1.4 FS.

This is because the structure is actually pretty strong already.   It has been designed to cope with the >1000psf Max-Q, 4-g acceleration and TO effects created by the Ares-I.

On Jupiter-130, to start with we fly through a much more benign flight environment (~700psf, 3.0g acceleration, no TO) so that reduces the loads considerably right out of the gate.

In addition, the SM is effectively removed from the load path, so it only has to support its own mass in tension.   From what we can tell so far, the design "as is" is plenty strong enough to support those different loads without change.


One other option which was suggested to us by someone at MSFC has also led us to looking at methods to possibly try to remove the CM from the load path of the LAS too.   Right now the ~7mT of LAS presses down on the CM structure during flight.   If we could remove that load, future variants of the CM could be made a fair bit lighter.   So we are investigating ways of potentially taking the LAS mass loads through the BPC and straight into the PLF, bypass the CM structure altogether.   It's just a design exercise right now, but could offer some interesting advantages later.


For now, our priority is to create a situation where the Orion project can stop worrying about weight limitations, high Dynamic Load Environments and Thrust Oscillation-related issues entirely.   And coupled together with greater funding available sooner, they can hopefully press-on as swiftly as possible towards a much sooner IOC with no further delays.

Ross.
« Last Edit: 06/01/2009 08:12 PM by kraisee »
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Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #57 on: 06/01/2009 08:07 PM »
...
Speaking of which.. 
Ross... any further word on dropping vectoring control on SRB nozzles?

Hey ! Fixed nozzle SRBs were considered by MSFC as of last year (to my knowledge) in the context of Ares V. Now, compare the [roll] control authority of 6 RS-68 @ 10m v. 3 SSME @ 8.4m (roughly; and even with the 4seg to 5 or 5.5 seg difference). Eh ? Let's give Caesar what is Caesar's.

Just to confirm, our studies show that the roll control of two SSME's would be more than sufficient to the task of providing complete roll, pitch and yaw control authority to the Jupiter-sized stack with fixed SRB nozzles.   Three SSME's provides even greater authority and 4, greater again.

Ross.
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Offline pierre

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Re: DIRECT v3.0 - Thread 1
« Reply #58 on: 06/01/2009 08:33 PM »
Would an ATV fit inside the Shroud? Could lift one basically "for free" if the case.  let it do it's own docking.

Yes, if Jupiter can lift an Altair (which is frakking huge!) then pretty much anything else can fit inside it.

You can probably put on it two fully-loaded ATVs side-by-side and an Orion on top: Jupiter 130 should happily handle them volume- and mass-wise.

Offline robertross

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Re: DIRECT v3.0 - Thread 1
« Reply #59 on: 06/01/2009 08:38 PM »
Ross & team: you all did a stellar job with that video & images. Thank-you so very much for all the hard work you obviously put into it.

Since I took a more in-depth view of this proposal long ago, I knew THIS architecture was the way to go. Simple and elegant. Bravo!!

Fingers crossed for this fall & the panel's findings.
Remembering those who made the ultimate sacrifice for our rights & freedoms, and for those injured, visible or otherwise, in that fight.

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