Henry Spencer (whose wisdom is finally becoming available on the web, apparently) explains:
An experienced designer with more freedom to act might have realised that there was just too much optimism in the Ares I concept, that a shuttle SRB was simply too small as a first stage for a rocket carrying the relatively heavy Orion spacecraft. There were several ways to handle the situation, but in my opinion the best was to just forget about Ares I entirely: build Ares V, or something like it, right away and use it for all the launches.
With a big launcher, there would be plenty of margin for weight overruns in development. Using the big launcher for Earth-orbit missions would obviously permit much heavier payloads there. Moreover, the lunar missions would get greater margins too, because they'd be done with two big launches rather than a big one and a little one, so they could weigh almost twice as much.
There is also an important pragmatic issue: the biggest threat to NASA's return to the Moon is the possibility that Congress will delay or cancel development funding for Ares V. Doing Ares V right away, and using it for the Earth-orbit missions as well as the ones to the Moon, would have ensured that this crucial element of NASA's plans actually gets built.
Of course, better yet would have been a focus on in-space infrastructure, drawing on ISS assembly experience, to allow us to use existing launchers. That would have also freed up money for earlier development of injection stages and landers, and made lunar missions much more of a fait accompli by now.
The story was told that the Saturn Ib was so expensive, that some thought it cheaper to build Saturn V in larger quantities and use that for both lunar and Earth orbit Apollo missions.
That and leave orbital access to commercial providers and develop just the lunar hardware in-house.
http://www.spacex.com/FalconLunarCapabilityGuide.pdf
Or replace the Saturn Ib with the three engine, two stage Saturn V INT-20 variant. Same tooling, etc as the Saturn V's.
The problems with Ares I have NOTHING to do with the fixed thrust of the SRB and the escalating size and mass of the payload, and EVERYTHING to do with the acoustical and vibration environments, which were known from day 1.
I disagree, "Conmen". Vibration isn't a serious problem in itself. There's all sorts of passive damping mechanisms out there. It just adds mass to the vehicle. It's a major problem because the fit is already so tight.
+-6 gees is no ordinary vibration, coupled with the already harsh acoustic and low amplitude vibration environment of the solids. Not using solids is a no brainer especially considering the elevator like ride afforded by POGO suppressed cryogenic liquid engines.
Consider the payload and passengers.
Seriously, Ares I supporters are either :
1) completely ignorant of fundamental physics
2) completely ignorant of fundamental logistics
3) completely ignorant of fundamental economics
4) completely ignorant of existing tested technology
5) completely ignorant of flight rated vehicles.
Ares I supporters are basically ignorant Americans.
Plenty of them out there. GO ARES I!!! U Rah.
That's why Direct team does not like Ares. It does not perform. Kill Ares now, or have it take the whole space program down with it!!