Author Topic: DIRECT v2.0 - Thread 2  (Read 921012 times)

Offline wannamoonbase

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Re: DIRECT v2.0 - Thread 2
« Reply #4480 on: 01/13/2009 07:39 PM »
Sorry, feeling a bit post happy today...

FYI a 5 seg SRB weighs almost 1.6 million lbs ready to go.  Unlike a liquid engine, you have to carry all that mass to the pad (liquids fill at the pad).  They weigh almost an order of magnitude more than the empty tank / spacecraft.  Thus, adding two more doubles your weight and is much to heavy for the crawler - so upgrade crawler, and for the crawler way - so rebuild path.  It's just way too expensive when you could better design your spacecraft.

Good golly Miss Molly, I can't imagine the MLP, crawler and crawler way required for a 4 SRB vehicle.  Not to mention flame trench changes for that level of thrust.

It could be built it would be amazing but WOW! 
Jonesing for a copy of 'Tales of Suspense #39'

Offline spacecase

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Re: DIRECT v2.0 - Thread 2
« Reply #4481 on: 01/13/2009 07:59 PM »
I am assuming the longer SRB's give you longer burn times rathar than just more (thrust), but I'm not sure.  As I understand they burn from the inside out, top to bottom, so a reduced orafice will extend burn time?

Lobo,

Solids produce more thrust when there is more surface area and burn for a longer time when there is more thickness to the propellent.

So for a general rule of thumb:
* Longer = more thrust
* Wider = more burn time

Offline gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4482 on: 01/13/2009 08:58 PM »
Just found that the popular mechanics news made it as far as some tech blog called Gizmodo. Random blogs and websites have really picked it up.

It is great that it went so far, but the downside is you now have the general public discussing Direct and Ares, many times without people "in the know" to clear up some of the mud.

On another note, do you think it would be worth starting a Direct facebook group? Something like "Space Fans for Direct" for a "1 million for Direct" group?
« Last Edit: 01/13/2009 09:02 PM by gladiator1332 »

Offline bad_astra

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Re: DIRECT v2.0 - Thread 2
« Reply #4483 on: 01/13/2009 09:06 PM »
Call it Direct Fanboys just for the benefit of He-Who-Shall-Not-Be-Named-But-Lurks-Here
"Contact Light" -Buzz Aldrin

Offline gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4484 on: 01/13/2009 09:08 PM »
I'm thinking of going with "I'm A Direct Fan Boy, and Proud Of It!"

Offline Jim

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Re: DIRECT v2.0 - Thread 2
« Reply #4485 on: 01/13/2009 09:16 PM »

That would be the same Lockheed-Martin that gave us the mass estimates for X-33 and Venture-Star?

That was Skunkworks and not Denver/ULA

Offline Jim

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Re: DIRECT v2.0 - Thread 2
« Reply #4486 on: 01/13/2009 09:26 PM »

Existing? Human rated Delta doesn't exist yet as far as I know.

same goes for Ares I, it doesn't exist.  But Delta IV is flying

Define human rated.
 
Additionally, Ares I doesn't meet the human rating requirement that existed one year ago

"manrating" a Delta IV isn't a big deal

Offline gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4487 on: 01/13/2009 09:27 PM »
If you have a facebook, here is the group:

http://www.facebook.com/group.php?gid=45545713366

Offline Jim

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Re: DIRECT v2.0 - Thread 2
« Reply #4488 on: 01/13/2009 09:28 PM »
Fifth is the fact that the SRB's were never designed to be utilized in this fashion with hundreds of tons of stage and payload on top.   They just weren't designed for these loads.

Why are these loads a big issue for the SRB, but not for Jupiter's ET-based core stage?  Is it because the core (being mostly tanks holding the liquids) can be redesigned to handle the loads, but the SRB can't be modified similarly?

Steve

Ross months ago I showed that the Ares I and Shuttle put the same loads on the SRB.  Remember the SRB lift from the forward attachment

Offline Bill White

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Re: DIRECT v2.0 - Thread 2
« Reply #4489 on: 01/13/2009 09:33 PM »
I'm thinking of going with "I'm A Direct Fan Boy, and Proud Of It!"

Perhaps flip this triangle over and print the Jupiter logo and the above slogan on this product

then distribute "Fanboy fans"

Pity CafePress doesn't seem to offer fans.
EML architectures should be seen as ratchet opportunities

Offline gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4490 on: 01/13/2009 09:35 PM »
Just wondering, would it be possible to provide the image that is currently the background at directlauncher.com?

Really great image.


Offline Lee Jay

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Re: DIRECT v2.0 - Thread 2
« Reply #4491 on: 01/13/2009 09:36 PM »
Fifth is the fact that the SRB's were never designed to be utilized in this fashion with hundreds of tons of stage and payload on top.   They just weren't designed for these loads.

Why are these loads a big issue for the SRB, but not for Jupiter's ET-based core stage?  Is it because the core (being mostly tanks holding the liquids) can be redesigned to handle the loads, but the SRB can't be modified similarly?

Steve

Ross months ago I showed that the Ares I and Shuttle put the same loads on the SRB.  Remember the SRB lift from the forward attachment

Don't the fifth segment and the structural resonance with the upper stage increase those loads?

Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #4492 on: 01/13/2009 09:37 PM »
1. Negative 11 nm x 100 nm is not an orbit - it's a crash and it's not useful for anything. It takes you 11 nautical miles beneath the surface of the earth.

That "orbit" is a trajectory that safely disposes of the US just as Shuttle does with ET. If you bring with you the US to a stable orbit, then you need to deorbit your US (some solids and pyrotechnics involved... again impacting LOC/LOM). But now since the US is insulated in foam, you can't deorbit the popcorns...

He specifically referred to it as an "orbit", not a trajectory.
Quote
-11x100nm is useful orbit for Orion.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Jim

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Re: DIRECT v2.0 - Thread 2
« Reply #4493 on: 01/13/2009 09:52 PM »
It was just an analagy.  But the my point is still converting an exsting vehicle to do something it was never intended to do, -can- be much more involved than one thinks it might be, and in the end, you can end up with basically a morphidite in a role it was never intended for and a purpose built-vehicle would have been a better option.
The SST was never intended to carry nose payload, or have thrust directly under it, or go beyond LEO.
This is part of the issues with those thinking about using the EELV's for man missions. 
The shuttle ET, there is no other name, as modified for Direct, doesn't leave LEO.

NASA, not just Direct, had plans to put payloads on the nose of the ET, on the aft of the ET, extend the length of the ET for propellant, use it for the basis of the NLS Core.  So what if is wasn't designed for it, it can be easily modified to do this because the diameter stays the same.  Length, skin gage or what attaches to the ends are easy changes.

This is standard practice. 
Titan II became T-III with the strengthening of the core to accept the largest SRM's at the time.  Per your post, this shouldn't happen since the T-II wasn't designed that way.  That is partially correct.  The core was no longer a T-II but a T-III (it was slightly heavier).  The same thing will happen with the shuttle ET, it will be come a Direct core.  The two are not interchangeable.

To continue, the T-III, became the T-34D and then the T-IV.

The same thing occurred with Thors having solids added and the tapered LOX tank being made into a constant 8' cylinder. 

The Atlas to accept the Centaur had skin gage thickness change and a constant 10' diameter.   It also had SRM's added.

So in all, the change of a shuttle ET into a Direct core is not a big deal.  It is all within standard LV experience.

BTW the orbiter does lift the ET from the aft, just a little to the side. 

Additionally, the change from ET to Direct is easier than from Direct to ET, if Direct was designed first

Offline kraisee

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Re: DIRECT v2.0 - Thread 2
« Reply #4494 on: 01/13/2009 10:17 PM »
Opening the new "THREAD 3" Here:

http://forum.nasaspaceflight.com/index.php?topic=15541.0

This thread will be locked now.

Ross.
« Last Edit: 01/13/2009 11:57 PM by Chris Bergin »
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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