I don’t remember what the Shuttle-C plan was regarding the engines. I wish they’d replace those overly complex, maintenance nightmare SSMEs with something simpler. Maybe something with a plug flow nozzle. Yes, I know, that would be waaay too cutting edge for NASA. I shudder to think how much money they could waste on something like that.

I agree. The proposed Apollo on Steroids will have two safety features that the Shuttle doesn’t, which are the escape tower tractor rocket system, and a sturdier heat shield.

Aside from the foam shedding and thermal protection system issue, the launch vehicle for the capsule and its service module will be less safe than the present Shuttle system. Why? Because it will be a three stage missile, instead of being a two stage missile as is the Shuttle, so there will be two stage separation events instead of one. ( That’s one argument for single stage to orbit spacecraft — no stage separations to malfunction. )

Furthermore, there is no valid way to estimate the safety of the parachute landing for the big new crew capsule. I believe it will be a record-sized weight to land under steerable parachute. That’s uncharted territory.

If you want to compare to Soyuz, Soyuz has had one fatal parachute malfunction and at least a couple of nonfatal but scary parachute incidents, most recently in 2003.

My thought is, flying winged Orbiters umanned might mitigate fears about the thermal protection system.

Unless Shuttle-C could ascend with more than one ISS structural module at a time, I’m sorry, but I’m skeptical about the value of Shuttle-C. Buidling a large diameter spherical section heat shield to return the three main engines and two Orbital Maneuvering pods and have the payload-bearing rails attach at the edges of or behind the heatshield — that sounds like a challenging design assignment.

Building a reuseable Shuttle-C might actually cost more than building another winged Orbiter.

I can’t find a Web link to back this up, but I think NASA Marshall has considered a Shuttle-C with a disposable, non-recoverable terminal stage — no heat shield and no parachute for the main engines. This disposable Shuttle-C makes a certain amount of sense to me, provided that it could carry more than one ISS module at a time.

I suppose the main engines could be left in space, with the intention of disassembling them and bringing back to Earth in Shuttle Orbiter cargo bays.

“While the Shuttle has a 1/200 loss rate (crew and vehicle) on ascent, Connolly said that NASA has calculated the CLV/CEV system as having a 1/2000 loss rate.”

Are they seriously trying to pitch this? They can claim they will increase the safety of the new vehicle by an order of magnitude by integrating an escape system, but they cannot claim any improvement in vehicle reliability. This is probably one of those PR lies they are trying to propogate like they did the safety rate for the shuttle prior to Challenger. The 1 in 200 rate for shuttle is bogus. The real number is 1/78, and it has come darn close to that in actual experience.

The reason a shuttle-c carries more payload is because it does not have to carry wings and landing gear to orbit. Also, without these, it is not vulnerable to foam or other projectiles shed by the tank.

I believe shuttle-c could lift about 3 times the mass of what the current orbiter can carry. The biggest problem is, if you don’t lengthen the cargo area, your cargo density becomes unrealizable. That was why the shuttle-c design NASA was recently proposing in their little “trade study” was so ridiculous. It looked like they lengthened the cargo bay significantly without checking its impact on the vehicle aerodynamics. Just one more example of the uselessness of trade studies. It would most likely be possible to lengthen the cargo area some without screwing up the aerodynamics, which would allow at least two shuttle payloads to be stacked into the bay. Additional mass could be added by increasing the cargo density. In a station module, this might mean adding a few racks to the interior.

The shuttle reacts payload loads through the rails that run longitudinally along either side of the bay. A payload fairing could be produced for an EELV that would react the loads in the same way allowing them to carry space station hardware aloft. They could do that, but won’t because of the control issue. NASA wants control of the vehicle. They don’t want the USAF involved.

Revised NASA Shuttle Plan Includes Most Station Hardware

By Brian Berger
Staff Writer

NASA expects to fly 19 space shuttle missions between 2006 and the orbiter fleet’s planned retirement in 2010 …

According to the preview of the S/SCOT study results, NASA thinks it can accomplish 18 flights to the space station beginning with STS-121 — the second so-called Return to Flight mission it now hopes to launch in May — plus one mission to service Hubble, for a total of 19 flights. One of the assumptions underlying the new station assembly plan is that the shuttle orbiter fleet will be retired before Oct. 1, 2010, the start of the U.S. federal government’s new budget year.

Building the international space station is taking much longer than NASA and its partners ever expected. An assembly plan finalized in September 1997, one year before on-orbit construction actually began, envisioned completing the orbital outpost by late 2003.

The space shuttle fleet made 13 flights to the space station before the Space Shuttle Columbia’s fatal accident in February 2003. NASA has deployed no major hardware at the station since November 2002, when the Space Shuttle Endeavour delivered the outpost’s first U.S.-built solar arrays. NASA does not expect to resume space station assembly flights before July 2006, the agency’s current planning date for attempting its third post-Columbia flight. Although STS-121 is bound for the space station, the mission’s primary purpose is to validate changes made after the Columbia accident, not deliver major hardware to the station.

http://www.space.com/spacenews/businessmonday_051010.html

Why not?

A question about Shuttle-C: could it lift more than one ISS structural payload at a time to ISS rendezvous? Define one payload here to be the payload a winged Shuttle Orbiter can carry.

( The weight of individual ISS modules is not a challenge. I don’t think any of them weigh more than roughly 25,000 pounds mass. )

If yes, I expect that a separate space tug, a.k.a. Orbital Maneuvering Vehicle, would be needed to mate the two or more structural modules with the Space Station.

If Shuttle-C could deliver only one payload per launch, same as a winged Shuttle Orbiter, then why not build another Shuttle Orbiter, leaving the crew compartment unfinished with the intention of operating the new Orbiter unmanned?

That might be cheaper than building a heat shield and reusable back end for Shuttle-C. The unmanned Orbiter might also be able to mate its payload with the ISS without a separate space tug.

> > The idea has been studied by the EELV contractors, and appears very do-able. However, the information will probably never reach the space community, or the policy makers and lawmakers in DC. Mikey has been very active in suppressing any information relating to the use of EELVs for exploration.

So why didn’t Sean O’Keefe propose EELV to help finish ISS?

“The CLV will be built using a standard 4 segment Solid Rocket Booster (SRB) currently used by the space shuttle.”

and

“This [heavy launch] vehicle will use a modified Shuttle external tank, 5 Block II SSMEs and two 5 segment SRBs.”

How stupid is that? They are going to spend the money to redesign and requalify the solid rocket boosters to handle the additional pressure of a 5 segment burn, and then only use it on one of the two vehicles? Amazing! Of course, the whole concept of calling these “shuttle derived” designs is beyond belief. Their “derivation” is nothing more than an arbitrary constraint placed on a design that might otherwise benefit from the technology advances of the last 30 years. I doubt even the most uninformed public believes their heavy launcher is “shuttle derived”. That’s like installing a hand full of bolts out of the current external tank on your car and calling it “shuttle derived”. But the EELV simply would not do at all.