DIRECT v3.0 - Thread 1

[kraisee]

The debris cloud from the Titan IV was 3 miles (15,000 feet) across.  1,000 feet is not going to do any good if the SRBs go.

No, I'm talking about 1,000ft OUTSIDE of the debris field.

Ross.

[clongton]

The debris cloud from the Titan IV was 3 miles (15,000 feet) across.  1,000 feet is not going to do any good if the SRBs go.

We're talking 1,000 feet *more* than we already have, not *only* 1,000 feet. Initial analysis already puts Orion in the clear from a Jupiter, not by a lot, but *in the clear*. We're talking about increasing the margin by an *additional* 1,000 feet (maybe more). We like margin in everything, including this.

[Danny Dot]

Lowering the dynamic pressure doesn't help a lot in aborting off of an SRB.  Even a LAS that weighs 22,600 pounds still has problems. 

I started a new thread, because this problem effects Direct, side mount, and EELVs.  Take a look at my data there.

http://forum.nasaspaceflight.com/index.php?topic=18071.0

Danny Deger

Danny, is there anything that approaches a potential solution to this, particularly pertaining to DIRECT?

Jesse

Ross made good use of my model and came up with a clever idea that helped a lot.  In my opinion too close to declare victory.  For example I don't have enough confidence in the drag model of the SRB debris to say all is well.  When I simply increased the debris size from 1.5 foot radius to 3 foot radius, Orion was back into the debris field. 

Due to the lower dynamic pressure, Direct can probably get by with a 2 second delay to destroy the SRB.  This helps out.  Ares needs something like 3 seconds.  In both of these cases, SRB destruction has to be automated.  The timing is critical.  The SRB flies within feet of Orion about 5 seconds after abort.  It would be really, really bad if the 45th Space Wing guy blew up the SRB at this time.   If the SRB tumbled, it might tend to fly formation with Orion for a while, so training them to delay the destruct until the SRB clears Orion is not a good option.

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

We also don't know how close we can get to the radiating debris and not have the chutes melt.  I can add this to the model, but I need a copy of an Apollo report I use to have and even then it is at least two days full time to do this mod.  I would have to go 3 DOF instead of 2 DOF and literally track every piece of debris from the SRB.  Then there would be lots and lots of uncertainty on exactly how many and how big the pieces are.

It is amazing for me to think the low end lap top on my lap can actual do this work -- with margin to spare. 

Danny Deger

[cixelsyD]

Just wondering, on the shuttle if one SRB goes, won't both go? Is this debris cloud calculation done assuming both SRBs explode, or are we assuming just 1. Ares I only has one SRB albeit a larger one, so I would guess it's debris cloud is smaller.

[kraisee]

Okay, let me try to demonstrate what I'm talking about.

That is, if this screen capture works or not...   Please let me know if you have problems reading this avi (XviD MPEG 4 format).

Ross.

[ar-phanad]

Lowering the dynamic pressure doesn't help a lot in aborting off of an SRB.  Even a LAS that weighs 22,600 pounds still has problems. 

I started a new thread, because this problem effects Direct, side mount, and EELVs.  Take a look at my data there.

http://forum.nasaspaceflight.com/index.php?topic=18071.0

Danny Deger

Danny, is there anything that approaches a potential solution to this, particularly pertaining to DIRECT?

Jesse

snip

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

snip

Forgive my engineering ignorance, but is the same true for the MLAS? (or is that what you were referring to as the "LAS that weighs 22,600 pounds"?)

Jesse

[TrueBlueWitt]

Okay, let me try to demonstrate what I'm talking about.

That is, if this screen capture works or not...   Please let me know if you have problems reading this avi (XviD MPEG 4 format).

Ross.

No luck on work laptop(limited Video codecs).

Most likely I have a player on home system that will play it.

[mike robel]

Ross,

I have probably missed the announcment of your get together tomorrow night.  What time and where is it?

Sadly, my software test will keep me from gonig to the committee session.

Mike

[ar-phanad]

Okay, let me try to demonstrate what I'm talking about.

That is, if this screen capture works or not...   Please let me know if you have problems reading this avi (XviD MPEG 4 format).

Ross.

AVI works for me.

This is not factoring for a sustainer, correct?

Are there any benefits from increasing the angle of the separate vectors, say to 20°? Or are there other problems associated with that?

[Ronsmytheiii]

screen caps:

[Pheogh]

Okay, let me try to demonstrate what I'm talking about.

That is, if this screen capture works or not...   Please let me know if you have problems reading this avi (XviD MPEG 4 format).

Ross.

No luck on work laptop(limited Video codecs).

Most likely I have a player on home system that will play it.

Did you try VLC player?

[brihath]

Ross,

I have probably missed the announcment of your get together tomorrow night.  What time and where is it?

Sadly, my software test will keep me from gonig to the committee session.

Mike

Fishlips Restaurant
610 Glen Cheek Drive
Cape Canaveral, FL

I have 5:30 as the time.

[robertross]

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

Danny Deger

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

2) Does an SSME shut-down or throttle-back help any during abort?

[Lab Lemming]

The current shuttle flight path includes a throttle-down during max-Q.

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

Danny Deger

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

2) Does an SSME shut-down or throttle-back help any during abort?

[Lab Lemming]

Augustine commission has answered another batch of questions:

Q:   Would the committee consider calling for a moratorium on the disassembly of equipment and systems used by the Shuttle program which could be of value should an architecture other than Ares be selected for future development? If Constellation as currently formulated will continue unabated, wouldn't it be best to preserve other options as well?

A:   A moratorium as requested is outside the scope of the committee's charter.

[robertross]

The current shuttle flight path includes a throttle-down during max-Q.

I'm sorry, but that hurts...

[Danny Dot]

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

Danny Deger

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

2) Does an SSME shut-down or throttle-back help any during abort?

On 1. I don't understand.  Please explain more detail so I can model the abort conditions.

On 2. It might.  This can easily be modeled by reducing the thrust of the post abort booster.  Can someone crank the numbers on the acceleration of the stack with Orion gone but the SRBs thrusting?  Here is a screen shot of a 1 G booster and 2 seconds of warning time. I would like to cover the Challenger like case where the the SRB breaks off the stack though.

[Danny Dot]

Just wondering, on the shuttle if one SRB goes, won't both go? Is this debris cloud calculation done assuming both SRBs explode, or are we assuming just 1. Ares I only has one SRB albeit a larger one, so I would guess it's debris cloud is smaller.

I didn't model the total mass in the debris field at all.  I simply decided to model 100 randomly selected debris pieces.  Total debris field mass will be important in a radiant heat model.  And the most like case of SRB failure is range safety termination.  This will take out both SRBs at the same time.

Danny Deger

[ar-phanad]

The current shuttle flight path includes a throttle-down during max-Q.

I am thinking a sustainer needs to be added to the Orion abort motor.  Direct can handle the mass, but I don't know if NASA can handle the probable schedule slip to Orion.  The outer mold line will certainly change and this is going to hurt Orion schedule a lot. 

Danny Deger

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

2) Does an SSME shut-down or throttle-back help any during abort?

That includes, I think, both the SSME and the SRBs. The SRB propellant load is distributed throughout the tank to reduce thrust near max-Q. I assume DIRECT already has some measure of this.

Jesse

[robertross]

I'm not sure if these options were asked/considered yet:

1) What about taking a performance hit on the SSME on ascent to reduce Direct's velocity? Just burn for longer. I say this to give an option if the schedule doesn't permit time to develop a new LAS (or add a sustainer). Once a new LAS is qualified & accepted, then this can be used with full performance from the stack.

On 1. I don't understand.  Please explain more detail so I can model the abort conditions.

Right now Direct (and of course shuttle) runs the SSME at 104.5% of thrust. What if we back it down to 98% (or whatever turns out best) of thrust during ascent?? I'm not sure what the cut-off point would be where you need a certain minimum thrust level, but since there is margin in the Jupiters, dive into some of it to solve the crew abort scenario.

EDIT to add: And the SSME throttles down as it approaches Max Q as well, so if it stayed there, or throttled down even further while still keeping enough thrust, it could help in the critical phase(s).