Ed Kyle wrote:
Brian Thorn wrote:

Well, these pretty pictures are all definitely for public relations
and politics, not engineering. But you can easily make the same claim
about the LockMart Atlas-5 based heavy-lifter in this week's AvLeak.
At least for the SDLV, all the essential elements have either been
tested or are in service, even the 5-segment SRB. The Atlas 5 Super
Heavy seems to require new tooling for a wider core stage and a new
pad to launch it from.


That part of that AWST issue that I found most
interesting was the statement attributed to Boeing VP
Chuck Allen. He said that the Northrop/Boeing's CEV
design could be launch by *existing* Delta IV vehicles.
That does not jive with pronoucements made by both
Griffin and ATK officials that the EELVs would need
new upper stages (just like "The Stick") to lift CEV.

- Ed Kyle



Yes. The original CEV requirements were written so that
existing launchers could be used. That was kinda the point
of OSP and CEV. Limit the development costs by focussing on
one area and examine exactly what they need, not necessarily
what they want. Even then CEV was a lot heavier than other
manned vehicles in roughly the same class. (To date, IIRC, the
only operational manned vehicles to weigh in over 10
tons is Shuttle and the lunar lander. That is separating Apollo CM from
the Service module. I count the lunar module with its lander as one
piece as it was the minimal mass for its job, whereas the Service
Module in the CSM varied greatly in mass dependant upon its mission. I
*think* they might have used ASTP as the planning mass for the CEV).

Looking at http://www.astronautix.com/craft/cev.htm

The CEV requirements included:

* Support a minimum crew of four from the Earth's surface through
mission completion on the Earth's surface.
* Mass less than 15 to 18 tonnes (the precise value to be
determined in preliminary contract studies).
* Abort capability during all phases of flight. Preferably such
abort capability would be available continuously and independent of
Launch Vehicle (LV) or Earth Departure Stage (EDS) flight control.
* Integrate with the Constellation Launch Vehicle (LV) to achieve
low earth orbit.
* Integrate with the Earth Departure Stage (EDS) to achieve lunar
orbit.
* Integrate with the Lunar Surface Access Module (LSAM) to achieve
lunar surface mission objectives. Preferably the CEV would be capable of
transferring consumables to and from the EDS and the LSAM.
* Maximum use of existing technology.
* Open Systems Architecture. Referral common hardware and software
between equipment built for acceptance testing of the flight system and
the ground support equipment used to process the vehicle at the launch site.
* Simple interface between the CEV and Launch System to optimise
integration.
* Certification by test to the maximum extent possible.

seriously, the requirements are approximately identical to the one
for the Apollo CM with a LEO Service Module component. The ASTP
Apollo CSM massed about 15000kg, and there is a oof of weight that
could be trimmed off that. When you start to see numbers double
demonstated technologies 40 years old, alarm bells start ringing.
These guys have an agenda that is not on the paper in front of them.

Flat out: The SDLV being proposed for CEV violates the maximum
use clause. The requirements originally put out there as well as
historical evidence is that this can be done in the EELV range.
If you can do the CEV proposal on all existing launch hardware and be
able to concentrate additional development on the CEV itself, then
you have very little ancillary costs and those would be associated with
mating issues. But, to build both CEV and launch vehicle splits the
money available. It also fudges quite a bit on that "abort on all
phases" clause as SRB's abort stages tend to be "but the crew was
killed" type aborts.

Nah, I think politics won. They have a predetermined technical
solution and they are going to make sure it wins.