Evolved DC-X

[Danderman]

IMHO, one of the great errors of Dan Goldin and NASA in the 1990s was the failure to build on the DC-X program. Yeah, they tried for the X-33 home run, but they should have been aware of the dangers of putting all the eggs in the X-33/34 basket and attempted to build directly on the DC-X test campaign.

A re-designed DC-X built with lighter materials and maybe more engines that could fly faster and higher would have demonstrated more of the technologies that we found were lacking in the 1990s, including more robust avionics and manufacturing composite prop tanks. The jump from DC-X to X-33 was too great in reality, at a cost to the taxpayers for finding this out of $1 billion.

Similarly, we should have operated an X vehicle more advanced than X-15 in the period between X-15 and the Shuttle.

SpaceX is showing the benefits of evolved development, which has rarely been accomplished in America during the Space Age.

[edkyle99]

I believe that DC-Y was the proposed next step.  That would have cost $5 billion and would only have been able to put 9,000 kg into LEO from the Cape.

 - Ed Kyle

[whitelancer64]

The X-15 program ended in 1968. The Shuttle first flew test flights in 1977.

So there is a gap of 9 years. However, NASA was not idle during that period, do not forget that the M2-F1, HL-10, X-23 (PRIME), M2-F2, X-24 A and B, and M2-F3 aircraft were flying, all of which were lifting body aircraft and helped inform the design for the Shuttle.

[D_Dom]

DC-X overcame funding challenges same as every other program. The budget constraints of the time were not by Dan Goldin or NASA design. Hard for me to see the history as less than accomplishment on top of accomplishment. Not as fast as I expected watching men walk on the moon but nobody said it would be easy or affordable.

[Patchouli]

I believe that DC-Y was the proposed next step.  That would have cost $5 billion and would only have been able to put 9,000 kg into LEO from the Cape.

 - Ed Kyle

Add a small crew vehicle to the top of it and you'd have a transportation system.

It's a little short of lifting something like the HL-20 but if the payload can do part of the orbital injection it really improves the performance of a SSTO so it might actually be able launch something like that.

Moving the payload to the top would be one of the evolution I think a crew carrying variant would need.
This may actually end up being more mass efficient as well since there would be less intertank structure then the variant with an internal cargo bay.

[GClark]

I'll just leave this here. See pg.10.

[RanulfC]

I believe that DC-Y was the proposed next step.  That would have cost $5 billion and would only have been able to put 9,000 kg into LEO from the Cape.

 - Ed Kyle

Add a small crew vehicle to the top of it and you'd have a transportation system.

It's a little short of lifting something like the HL-20 but if the payload can do part of the orbital injection it really improves the performance of a SSTO so it might actually be able launch something like that.

Moving the payload to the top would be one of the evolution I think a crew carrying variant would need.
This may actually end up being more mass efficient as well since there would be less intertank structure then the variant with an internal cargo bay.

They payload bay was designed to minimize the CG changes with and without payload during any part of the flight profile. Putting payload on the nose definitely DOES cause major changes AND you have to design/operate a configuration capable of handling all loading from whatever payload is up there. Engineers tend to choose the relatively "easy" solution for some reason

Randy

[Danderman]

I believe that DC-Y was the proposed next step.  That would have cost $5 billion and would only have been able to put 9,000 kg into LEO from the Cape.

 - Ed Kyle

A bridge too far.

The actual fail came when DC-X terminated itself, and within a year or so, X-33 was in the works. There should have been a plan prior to the end of DC-X for an evolutionary next step.

[Danderman]

The X-15 program ended in 1968. The Shuttle first flew test flights in 1977.

So there is a gap of 9 years. However, NASA was not idle during that period, do not forget that the M2-F1, HL-10, X-23 (PRIME), M2-F2, X-24 A and B, and M2-F3 aircraft were flying, all of which were lifting body aircraft and helped inform the design for the Shuttle.

In hindsight, some sort of LOX-Kerosine or LH2 powered hypersonic vehicle should have been flight tested in the late 1960s as a Shuttle precursor and to test operations and turnaround. That would have informed Shuttle design a lot.  X-15 performance was constrained by its airframe and materials, so a more advanced airframe and better materials would have allowed more performance; much better engines were widely available by the late 1960s, and less dense and more efficient fuels would have mitigated heating loads.

[Patchouli]

They payload bay was designed to minimize the CG changes with and without payload during any part of the flight profile. Putting payload on the nose definitely DOES cause major changes AND you have to design/operate a configuration capable of handling all loading from whatever payload is up there. Engineers tend to choose the relatively "easy" solution for some reason

Randy

Having an escape system pretty much forces you to move any crew vehicle to the top of the vehicle.
As seen with the Chrysler SERV concept.
Sure you could try to eject from the side but it wouldn't work well for T+0 aborts and the internalized crew compartment would not be an idea reentry shape.
Plus it reduces the risk associated with landing which is why Blue Origin separates their capsule vs landing the complete stack.

[Kansan52]

When Blue Origin started, they built from the DC-X program. They hired everyone they could that was associated with the DC-X program. What they have now is an evolved DC-X.

[Patchouli]

When Blue Origin started, they built from the DC-X program. They hired everyone they could that was associated with the DC-X program. What they have now is an evolved DC-X.

I didn't know that I wondered if one of the new space companies tried to track a bunch of them down as they had already solved many of the problems with VTOL.
I wonder if Spacex hired any as well?

[TrevorMonty]

When Blue Origin started, they built from the DC-X program. They hired everyone they could that was associated with the DC-X program. What they have now is an evolved DC-X.

I didn't know that I wondered if one of the new space companies tried to track a bunch of them down as they had already solved many of the problems with VTOL.
I wonder if Spacex hired any as well?

One of the ex DCX engineers is in DARPA now and is behind XS1 program. XS1 would of made an ideal follow on program to DCX.

[Kansan52]

When Blue Origin started, they built from the DC-X program. They hired everyone they could that was associated with the DC-X program. What they have now is an evolved DC-X.

I didn't know that I wondered if one of the new space companies tried to track a bunch of them down as they had already solved many of the problems with VTOL.
I wonder if Spacex hired any as well?

My guess (and only a guess) is no. Blue was based around using DC-X so they would want that specific skill set. But other programs weren't based on DC-X. They wouldn't try for the entire team. That wouldn't stop them from recruiting from that pool.

[RanulfC]

They payload bay was designed to minimize the CG changes with and without payload during any part of the flight profile. Putting payload on the nose definitely DOES cause major changes AND you have to design/operate a configuration capable of handling all loading from whatever payload is up there. Engineers tend to choose the relatively "easy" solution for some reason

Randy

Having an escape system pretty much forces you to move any crew vehicle to the top of the vehicle.
As seen with the Chrysler SERV concept.
Sure you could try to eject from the side but it wouldn't work well for T+0 aborts and the internalized crew compartment would not be an idea reentry shape.
Plus it reduces the risk associated with landing which is why Blue Origin separates their capsule vs landing the complete stack.

Actually, it's one of those "assumptions" that in any abort for an "SSTO" and specifically the VTVL types is that you don't HAVE a "crew escape" system because the vehicle is designed to abort intact rather than separately. "After all, we don't have ejection seats on airliners!" is the most often actually stated reasoning

SERV is an interesting example since it also has an "internal" payload bay being the area directly under the glider (it has very limited on-board propulsion and "strap-on" escape rockets) on the model. Like a majority of SSTO proposals SERV wasn't really meant to fly with or deliver crew but was set up mostly for cargo. By putting the crew in a separate vehicle you do avoid some design issues but SERV also showed that doing so required a lot of work to characterize "nose" mounted payloads beyond the internal bay size.

The optimum solution turned out to be mounting a variable length "pole" on the vehicle with what we now call an "aerodisk" on it to enable various payloads to be carried with minimum disruption. The aerodisk basically created a "virtual fairing" of any desired size by a combination of length and disk size.

I should also point out that any design "evolved" from the DC-X has to deal with the "main" issue which is it was a design that was based on the idea of a NOSE FIRST (or forward anyway as the DC-Y would have been more a "lifting body" shape) which precludes any nose mounted payload. Due to cross-range and other "operational" considerations there wasn't any choice but a central payload bay. Once you're past that you are no longer talking "DC-X" design anyway so a LOT of options open up. (Which I actually consider a superior option/choice in the first place. The DC-X was very much self limited and not even close to the "best" SSTO design possible. Only the one that got "built" in any real capacity)

Randy

[RanulfC]

When Blue Origin started, they built from the DC-X program. They hired everyone they could that was associated with the DC-X program. What they have now is an evolved DC-X.

I didn't know that I wondered if one of the new space companies tried to track a bunch of them down as they had already solved many of the problems with VTOL.
I wonder if Spacex hired any as well?

My guess (and only a guess) is no. Blue was based around using DC-X so they would want that specific skill set. But other programs weren't based on DC-X. They wouldn't try for the entire team. That wouldn't stop them from recruiting from that pool.

Other than propulsion, DC-X has/had little in common with the majority of SSTO designs. As noted it was a "nose-entry" design with at least a "semi" lifting body design. Most VTVL designs are based on base/propulsion first reentry configurations. Everything I've seen is that Blue is NOT planning anything like the DC-X design other than both being a general "VTVL" design. SpaceX designs aren't even close to the same and both design choices and requirements are very different.

As to Blue's hiring practices I know at least one DC-X engineer who interviewed with BO but was not hired and in fact would not have accepted a job offer with them as they were "obviously" not going in the direction of building on the work of DC-X according to his job interview.
(IMHO his very vocal stance that "suborbital is only a stunt" and "anything short of a fully operational SSTO from the start is a waste of time and money" is probably a reason he wasn't even offered )

But my understanding is they mostly hired only propulsion and some design engineers from the DC-X program.

One of the ex DCX engineers is in DARPA now and is behind XS1 program. XS1 would of made an ideal follow on program to DCX.

That's a rather broad interpretation of "follow-on" as DC-X-etc were intended to prototype and prove SSTO operations and ability while XS-1 is designed to do the same with a reusable booster and not a fully orbital spacecraft

XS-1 is supposed to be a X-34-like reusable booster stage where as DC-X was never intended (or designed) to be anything but a Single-Stage-To-Orbit development vehicle.

Randy

[Kansan52]

Thanks RandulfC!

[RanulfC]

Speaking of an "advanced/evolved" DC-X and proposed X-33 configuration for the XS-1:
http://forum.nasaspaceflight.com/index.php?topic=13206.msg1480554#msg1480554

Randy

[Archibald]

One of the ex DCX engineers is in DARPA now and is behind XS1 program. XS1 would of made an ideal follow on program to DCX.

and that man is Jess Sponable, the author of the pdf linked higher in the thread. 

[ZachS09]

Fact about Jess Sponable:

He was selected as part of the second Manned Spaceflight Engineer corps and was born in Madrid, Spain.