A result of a study of the AIUS as a side-test.

[Downix]

While working on AJAX, I had a random idea for how to utilize the AIUS.  Studying it, I realized it would work.

The long and short of it, stretch the AIUS, attach an SSME on the bottom, put a normal AIUS on top of it, attach two 5-seg SRB's on either side.  Performance:
71mT

The problem was, it could not get higher performance, so would not meet the SLS requirements. Ah well.

[Zed_Noir]

Would a RS68 in the bottom change the performance?

[Downix]

Would a RS68 in the bottom change the performance?

You'd loose performance.  Higher thrust during the period of the flight where you don't need it (under SRB lift) while running out of fuel faster (low isp).  And you'd still have to develop the RD-68B, which is 6-8 years out, in order to survive the hellish conditions next to the SRB's and also to be safe for manned flight.

[spacenut]

Downix,
Did you try the Ares I US on top of AJAX?  What Performance. 

[Downix]

Downix,
Did you try the Ares I US on top of AJAX?  What Performance. 

Not worth the cost. Gained 3mt over the ACES.

[spacenut]

I thought the Ares I US was almost complete except for J2-x.  Would ACES be faster to develop? 

[Downix]

I thought the Ares I US was almost complete except for J2-x.  Would ACES be faster to develop? 

It is. But no suitable engine w/o J-2X.

Then again, I realized earlier, the J-2X isn't enough engine for the AIUS either. (The AIUS is 337,500 lbs, the J-2X only has 294,000 lbf)

[alexw]

I thought the Ares I US was almost complete except for J2-x.  Would ACES be faster to develop? 

It is. But no suitable engine w/o J-2X.
Then again, I realized earlier, the J-2X isn't enough engine for the AIUS either. (The AIUS is 337,500 lbs, the J-2X only has 294,000 lbf)

    Err, why not? Upper stage T/W < 1 is no special problem when flying a lofted trajectory, no?
         -Alex

[Downix]

I thought the Ares I US was almost complete except for J2-x.  Would ACES be faster to develop? 

It is. But no suitable engine w/o J-2X.
Then again, I realized earlier, the J-2X isn't enough engine for the AIUS either. (The AIUS is 337,500 lbs, the J-2X only has 294,000 lbf)

    Err, why not? Upper stage T/W < 1 is no special problem when flying a lofted trajectory, no?
         -Alex

I know, it's just something I'd not realized.  Explains why the 5-seg was necessary.

[Patchouli]

While working on AJAX, I had a random idea for how to utilize the AIUS.  Studying it, I realized it would work.

The long and short of it, stretch the AIUS, attach an SSME on the bottom, put a normal AIUS on top of it, attach two 5-seg SRB's on either side.  Performance:
71mT

The problem was, it could not get higher performance, so would not meet the SLS requirements. Ah well.

Ironic thing is that configuration probably has more in common with Ares I then Ares V did.

[Downix]

While working on AJAX, I had a random idea for how to utilize the AIUS.  Studying it, I realized it would work.

The long and short of it, stretch the AIUS, attach an SSME on the bottom, put a normal AIUS on top of it, attach two 5-seg SRB's on either side.  Performance:
71mT

The problem was, it could not get higher performance, so would not meet the SLS requirements. Ah well.

Ironic thing is that configuration probably has more in common with Ares I then Ares V did.

It does, every Ares I part is there, just an added first stage derived from the existing AIUS.

It also is more shuttle derived than Ares V to boot.

[luke strawwalker]

While working on AJAX, I had a random idea for how to utilize the AIUS.  Studying it, I realized it would work.

The long and short of it, stretch the AIUS, attach an SSME on the bottom, put a normal AIUS on top of it, attach two 5-seg SRB's on either side.  Performance:
71mT

The problem was, it could not get higher performance, so would not meet the SLS requirements. Ah well.

How about a three stager, using your SSME powered stretched AIUS for the first stage, with a J-2X powered AIUS second stage topped with another regular J-2X AIUS?? 

(grins)  Later!  OL JR

[Downix]

While working on AJAX, I had a random idea for how to utilize the AIUS.  Studying it, I realized it would work.

The long and short of it, stretch the AIUS, attach an SSME on the bottom, put a normal AIUS on top of it, attach two 5-seg SRB's on either side.  Performance:
71mT

The problem was, it could not get higher performance, so would not meet the SLS requirements. Ah well.

How about a three stager, using your SSME powered stretched AIUS for the first stage, with a J-2X powered AIUS second stage topped with another regular J-2X AIUS?? 

(grins)  Later!  OL JR

Wouldn't reach orbit due to weight.