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.

[Danderman]

New Shepard is almost precisely the kind of "evolved" DC-X vehicle that we should have been flying 20 years ago.

[Antilope7724]

Single Stage Rocket Technology (SSRT) DC-X Test Program Environmental Assessment
June 1992, 147 pg
http://www.dtic.mil/dtic/tr/fulltext/u2/a265940.pdf

[AlexA]

Some relevent reading:
Jerry Pournelle (SF author & member of the "Citizens Advisory Council on National Space Policy") on the origins of DC-X:
http://www.jerrypournelle.com/slowchange/SSX.html
Recomendations for follow-on programme:
http://www.jerrypournelle.com/slowchange/SSX2.html

[AlexA]

The book "Single Stage to Orbit: Politics, Space Technology, and the Quest for Reusable Rocketry" Andrew J. Butrica which covers DC-X and related projects is currently on sale for $9.99 on JHU (publishers) site:
https://jhupbooks.press.jhu.edu/content/single-stage-orbit

You can preview it on Google Books:
https://books.google.co.uk/books?id=v6eTVBEDA54C&lpg=PA1938&dq=single%20stage%20to%20orbit&pg=PA1938#v=onepage&q=single%20stage%20to%20orbit&f=false

[Chris_petty]

Currently reading this book and it's excellent so far - plenty of time spent setting the historical context which I feel is vital to understanding what happened and why with the SSTO projects of the 1980s/1990s

[Brovane]

The book "Single Stage to Orbit: Politics, Space Technology, and the Quest for Reusable Rocketry" Andrew J. Butrica which covers DC-X and related projects is currently on sale for $9.99 on JHU (publishers) site:
https://jhupbooks.press.jhu.edu/content/single-stage-orbit

You can preview it on Google Books:
https://books.google.co.uk/books?id=v6eTVBEDA54C&lpg=PA1938&dq=single%20stage%20to%20orbit&pg=PA1938#v=onepage&q=single%20stage%20to%20orbit&f=false

Looks like a great book at a great price, just ordered it.  Thank you for pointing it out. 

[AlexA]

Looks like a great book at a great price, just ordered it.  Thank you for pointing it out.

You're welcome.

I ordered it too - even with $10 shipping to UK it seems worth it.

[Chris_petty]

Possibly of interest to some on this thread, I'm currently writing a history of various vertical takeoff/landing space vehicles from the designs of Philip Bono, through SERV/MURP and on to DC-X.

Part 1 is here: https://thehighfrontier.wordpress.com/2016/03/20/straight-back-down-to-earth-a-history-of-the-vertical-takeoffvertical-landing-rocket-part-1/

As always comments and (polite) corrections welcomed 

[Antilope7724]

In light of the recent Falcon 9 1st stage recovery, I started to wonder what device made the first rocket powered vertical landing on landing legs?

I was thinking maybe the DC-X, but then I thought about the Apollo Lunar Module and the lunar landing Surveyor spacecraft that both landed vertically with rockets on landing legs.

Is there any earlier craft that landed vertically with rockets on landing legs? Seems like the Surveyor 1 was the first.

There was also the LLRV (Lunar Landing Research Vehicle) from around the same time, but it used rockets and a jet engine, so it wasn't a pure rocket landing.

[JasonAW3]

In light of the recent Falcon 9 1st stage recovery, I started to wonder what device made the first rocket powered vertical landing on landing legs?

I was thinking maybe the DC-X, but then I thought about the Apollo Lunar Module and the lunar landing Surveyor spacecraft that both landed vertically with rockets on landing legs.

Is there any earlier craft that landed vertically with rockets on landing legs? Seems like the Surveyor 1 was the first.

There was also the LLRV (Lunar Landing Research Vehicle) from around the same time, but it used rockets and a jet engine, so it wasn't a pure rocket landing.

Surveyor weould be my guess.

[kato]

Bell Rocket Belt? With biological landing legs that is...

[whitelancer64]

In light of the recent Falcon 9 1st stage recovery, I started to wonder what device made the first rocket powered vertical landing on landing legs?

I was thinking maybe the DC-X, but then I thought about the Apollo Lunar Module and the lunar landing Surveyor spacecraft that both landed vertically with rockets on landing legs.

Is there any earlier craft that landed vertically with rockets on landing legs? Seems like the Surveyor 1 was the first.

There was also the LLRV (Lunar Landing Research Vehicle) from around the same time, but it used rockets and a jet engine, so it wasn't a pure rocket landing.

Luna 9, which landed on the Moon February 3, 1966, used an airbag to cushion its landing, so yes, the first landing on legs was by the second probe to successfully soft-land on the Moon: Surveyor 1 on June 2, 1966.

[Antilope7724]

Bell Rocket Belt? With biological landing legs that is...

I believe you are correct. There was a 2 man version that did have short landing legs. So that may have been earlier than Surveyor 1.

[Chris_petty]

for those interested in the story leading up to the DC-X, here's Part 2 of a series I'm writing on VTOL Rockets which deals with developments in the 80's which directly led to the programme:

https://thehighfrontier.wordpress.com/2016/04/07/taking-star-wars-to-the-stars-a-history-of-the-vtol-rocket-part-2/

[TrevorMonty]

Nice article.

Sent from my ALCATEL ONE TOUCH 6030X using Tapatalk

[Elmar Moelzer]

I was very sour about the cancellation of the DC-X (and follow ups). NASA never treated that program well and were probably happy to cancel it. They wanted something with wings for some reason.
If they had chosen Boeings proposal for the X-33, we would have seen something very close to a DC-X follow up vehicle. But they wanted to not only have horizontal landing but at the same time test all sorts of risky new technologies in one X- vehicle like composite tanks, lifting bodies and aerospike engines.
All of that completely underperformed.
The X-33 was a total disaster that went nowhere. But hey, at least Lockheed got a lot of money for it. LOL

My favorite VTOL SSTO is still the Phoenix designed by Gary Hudson (who frequents this forum as well). I was always hoping that someone would give him the funding to at least develop a small prototype.
Regarding the DC-Y. It was already meant to be manned and the payload was not that small for a first generation SSTO RLV. It could have increased with maturing technology (just look at the huge leaps the F9 has taken since the first version).

[Chris_petty]

Currently, I think it's really interesting to look at what Masten Space Systems are proposing for the DARPA XS-1. From what I've seen, there are real echoes of the DC-X/DC-Y there. The fact that Jess Sponable is running the programme for DARPA and the goals are very much in line with what he was aiming for with those earlier programmes really makes this look very familiar. Of course this is proposed as a TSTO vehicle and we will see winged proposals from other players, but the phase 2 goal of hardware flying 10 times in 10 days seems a real extension of Max Hunter's original SSX concept.

Masten did show some concept art at Space Access in Phoenix this year - attached is an image they posted on Instagram

[Archibald]

It looks a bit like McDonnell Douglas entry in the X-33 program

 

[TrevorMonty]

Could these XS-1 vehicle be used as basis for a reusable US. The heatshield would need to handle higher temperatures, so some extra weight there. Engine count could be reduce as they don't need >1:1 thrust to weight ratio.

This maybe what Blue has in mind for the Boeing entry.



Sent from my ALCATEL ONE TOUCH 6030X using Tapatalk

[Chris_petty]

Re. Similarities to the McDonnell Douglas X-33, another image that has been doing the rounds recently for a Masten XS-1 looks even more like that, but I have no idea as to the provenance of this concept - it doesn't appear on Masten's site so may have no link to the company or their actual plans.

Does anyone know more? Also does anyone know if there are videos of the Masten or DARPA (XS-1) presentations from this year's Space Access available anywhere online?

[strangequark]

Re. Similarities to the McDonnell Douglas X-33, another image that has been doing the rounds recently for a Masten XS-1 looks even more like that, but I have no idea as to the provenance of this concept - it doesn't appear on Masten's site so may have no link to the company or their actual plans.

Does anyone know more? Also does anyone know if there are videos of the Masten or DARPA (XS-1) presentations from this year's Space Access available anywhere online?

This image is from a Popular Mechanics article on Masten. It's older than the imagery from Space Access. Neither are mere concept art.

[savuporo]

Worth noting that ISAS in Japan flew their own DC-X for a while ( the RVT ) and then stopped. Hydrolox and everything

[Oli]

Masten did show some concept art at Space Access in Phoenix this year - attached is an image they posted on Instagram

That concept has some weird wings at the back. I wonder why they look that way.

[RanulfC]

Masten did show some concept art at Space Access in Phoenix this year - attached is an image they posted on Instagram

That concept has some weird wings at the back. I wonder why they look that way.

Look like "box" or "joined" wings which are stronger with more wing area than separate smaller winglets. There's some possible issues with heating during re-entry but we can assume they know what they are doing

The larger wing area total would allow better lift on entry and fly-back while not being as draggy and difficult to account for during a vertical landing or so the idea goes.

Randy

[Oli]

Masten did show some concept art at Space Access in Phoenix this year - attached is an image they posted on Instagram

That concept has some weird wings at the back. I wonder why they look that way.

Look like "box" or "joined" wings which are stronger with more wing area than separate smaller winglets. There's some possible issues with heating during re-entry but we can assume they know what they are doing

The larger wing area total would allow better lift on entry and fly-back while not being as draggy and difficult to account for during a vertical landing or so the idea goes.

Randy

I doubt they can do fly- or glide-back with those wings (?). If they could it would make no sense to land vertically. I find it a bit curious they chose such a reentry shape for a first stage. It might be useful for downrange landing on a platform, since no propulsive slowdown is required, but for RTLS it doesn't seem worth it (assuming it cannot glide/fly over long distances).

[wizzard3]

the wing shape comes from http://synergyaircraft.com/
it lowers the landing speed

[Robotbeat]

Masten did show some concept art at Space Access in Phoenix this year - attached is an image they posted on Instagram

That concept has some weird wings at the back. I wonder why they look that way.

Look like "box" or "joined" wings which are stronger with more wing area than separate smaller winglets. There's some possible issues with heating during re-entry but we can assume they know what they are doing

The larger wing area total would allow better lift on entry and fly-back while not being as draggy and difficult to account for during a vertical landing or so the idea goes.

Randy

I doubt they can do fly- or glide-back with those wings (?). If they could it would make no sense to land vertically....

There's a lot of room between "L/D = 0" and an aircraft-like "L/D = 5."

You can still get some benefit from the L/D even if you're better off vertically landing after all the gliding (which doesn't actually use a lot of propellant if you do so promptly).

[RanulfC]

I doubt they can do fly- or glide-back with those wings (?). If they could it would make no sense to land vertically. I find it a bit curious they chose such a reentry shape for a first stage. It might be useful for downrange landing on a platform, since no propulsive slowdown is required, but for RTLS it doesn't seem worth it (assuming it cannot glide/fly over long distances).

As Robotbeat notes between those "wings" and body lift you can probably get a very good distance/cross-range L/D even if it's not on par with a "standard" winged body.

As I pointed out the design looks like it uses a DCX type reentry though more on it's side than nose first.

the wing shape comes from http://synergyaircraft.com/
it lowers the landing speed

Actually the "closed wing" design was experimented with right after the Wrights first flight and has many more advantages than "just" lowering landing speed if used for lifting landing Various search terms would include, "diamond-wing", "closed wing", "box wing" , and "joined wing" configurations.

Randy

[Chris_petty]

Just posted the final instalment of my 3 part history of VTVL rockets covering Roton through to the present day. Thanks to those of you who've pointed out omissions etc. I'll be updating the articles as I get more info:

https://thehighfrontier.wordpress.com/2016/04/25/launch-land-repeat-a-history-of-the-vtol-rocket-part-3/

[Oli]

I doubt they can do fly- or glide-back with those wings (?). If they could it would make no sense to land vertically. I find it a bit curious they chose such a reentry shape for a first stage. It might be useful for downrange landing on a platform, since no propulsive slowdown is required, but for RTLS it doesn't seem worth it (assuming it cannot glide/fly over long distances).

As Robotbeat notes between those "wings" and body lift you can probably get a very good distance/cross-range L/D even if it's not on par with a "standard" winged body.

It rules out fly back and if you do (partial) boost back why not standard wings that let you glide farther and land on wheels? It seems to combine the disadvantages of wings and vertical landing.

[Donosauro]

Worth noting that ISAS in Japan flew their own DC-X for a while ( the RVT ) and then stopped. Hydrolox and everything

Interesting! Looks like they never flew higher than 42 meters, and that the follow-on to that model did not fly at all, which may go a ways toward explaining why the effort is not better known. From the Wikipedia page, it all seems to have been very methodical, though: https://en.m.wikipedia.org/wiki/Reusable_Vehicle_Testing

There are no images on the Wikipedia page, but it does have a link to this page which has images of a printable model: http://www.currell.net/models/rvt.htm

[savuporo]

Worth noting that ISAS in Japan flew their own DC-X for a while ( the RVT ) and then stopped. Hydrolox and everything

Interesting! Looks like they never flew higher than 42 meters, and that the follow-on to that model did not fly at all, which may go a ways toward explaining why the effort is not better known. From the Wikipedia page, it all seems to have been very methodical, though: https://en.m.wikipedia.org/wiki/Reusable_Vehicle_Testing

There are no images on the Wikipedia page, but it does have a link to this page which has images of a printable model: http://www.currell.net/models/rvt.htm

You can read an interview with the mastermind of this effort here : http://www.hobbyspace.com/AAdmin/archive/Interviews/Systems/Inatani.html

[Kansan52]

Just posted the final instalment of my 3 part history of VTVL rockets covering Roton through to the present day. Thanks to those of you who've pointed out omissions etc. I'll be updating the articles as I get more info:

https://thehighfrontier.wordpress.com/2016/04/25/launch-land-repeat-a-history-of-the-vtol-rocket-part-3/

Thanks! Never knew the connection between the DC-X and Roton.

So New Shephard, Al Shephard. Big Brother Rocket should be Big Gus after Gus Grissom?

[the_other_Doug]

Just posted the final instalment of my 3 part history of VTVL rockets covering Roton through to the present day. Thanks to those of you who've pointed out omissions etc. I'll be updating the articles as I get more info:

https://thehighfrontier.wordpress.com/2016/04/25/launch-land-repeat-a-history-of-the-vtol-rocket-part-3/

Thanks! Never knew the connection between the DC-X and Roton.

So New Shephard, Al Shephard. Big Brother Rocket should be Big Gus after Gus Grissom?

Well -- except that Al Shepard didn't spell his name "Shephard" or "Shepherd," so if Bezos meant to invoke the name of "the first free man in space", he didn't do it very well... 

Though I bet Gus, who at 5'5" was the shortest guy in the astronaut office during his time, would be tickled to have something named "Big Gus" after him...

[Kansan52]

Where's an 'Embarrassed' emoji when needed!

And Yes, I think Gus would enjoy 'Big Gus'.

[RanulfC]

I doubt they can do fly- or glide-back with those wings (?). If they could it would make no sense to land vertically. I find it a bit curious they chose such a reentry shape for a first stage. It might be useful for downrange landing on a platform, since no propulsive slowdown is required, but for RTLS it doesn't seem worth it (assuming it cannot glide/fly over long distances).

As Robotbeat notes between those "wings" and body lift you can probably get a very good distance/cross-range L/D even if it's not on par with a "standard" winged body.

It rules out fly back and if you do (partial) boost back why not standard wings that let you glide farther and land on wheels? It seems to combine the disadvantages of wings and vertical landing.

Standard wings add drag and additional aeroloads going up and overall extra mass to the vehicle, ditto wheels. If you're boosting back having "real" wings is going to be irrelevant anyway since most of your return will be propulsive. "Gliding" back, (especially for a first stage) has been found to be marginal which is why boost-back has become the new standard. In most cases of an optimum performance launch profile the booster reentered down range far enough that it required an auxiliary propulsion system to provide propulsion which meant it was a "fly" back rather than a "glide" back design. Again that's extra mass and systems which in most cases ended up being more than extra propellant to preform a boost-back instead. And if you're boosting back, even "partially" you need less lifting capability to do so and again it all comes down to the trades being done. Masten's trade seems to indicate that boost-back and vertical landing trade better than full wings and wheels which is what LM/Boeing/et-al were proposing.

Randy

[Oli]

"Gliding" back, (especially for a first stage) has been found to be marginal which is why boost-back has become the new standard.

According to this you can glide back from staging at more than Mach 3, not exactly marginal.

In most cases of an optimum performance launch profile the booster reentered down range far enough that it required an auxiliary propulsion system to provide propulsion which meant it was a "fly" back rather than a "glide" back design. Again that's extra mass and systems which in most cases ended up being more than extra propellant to preform a boost-back instead.

Define "most cases". The higher the staging velocity the better is fly back.

And if you're boosting back, even "partially" you need less lifting capability to do so and again it all comes down to the trades being done.

Then why lifting capability at all? Do it like SpaceX/Blue Origin.

[RanulfC]

"Gliding" back, (especially for a first stage) has been found to be marginal which is why boost-back has become the new standard.

According to this you can glide back from staging at more than Mach 3, not exactly marginal.

You might want to read the whole thing and especially the discussion and conclusion section again. Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage. While the cost of the booster is somewhat lower due to not needing significant TPS the overall cost of the launch system is much higher. Glideback REQUIRES that the booster fly no faster than Mach-3 and no further down-range than 40-55 nautical miles or glideback is not possible. Flyback can have both a higher staging speed and a more distant reentry and return maneuver but that's because you now have to include an atmospheric propulsion system and automated guidance system capable of guiding the vehicle back to the launch site from hundreds of miles away. The flyback engines and fuel, along with the need for TPS to deal with the higher reentry speed mean the booster is bigger and heavier, though the higher staging speed means the upper stage is lighter and lower cost than for glideback. Finally boost-back and glideback has a lower staging velocity than flyback so the upper stage is larger and more expensive but slightly higher than simple glide back and is the "preferred" method in the cited thesis. However the upper stage is still has to provide significantly more delta-v due to the lower staging velocity and the operations are restricted due to the need to keep a certain amount of propellant for the boost back maneuver.

The key restriction throughout the whole thesis is the need to return to the launch site as there is no-where else to recovery the booster BECAUSE it is a gliding vehicle. The bias of requiring wings and wheels to be included in the design highly restricts the operational use of the system where as if the vehicle were VTOL operational use is greatly expanded as shown by SpaceX Falcon-9 operations. (No you can't land the proposed booster on "a barge or converted aircraft carrier" before anyone asks. The vehicle is over 160 feet long with a 110 foot wingspan and would require a thousand foot runway. Also no, putting a tailhook on it isn't an option either )

In most cases of an optimum performance launch profile the booster reentered down range far enough that it required an auxiliary propulsion system to provide propulsion which meant it was a "fly" back rather than a "glide" back design. Again that's extra mass and systems which in most cases ended up being more than extra propellant to preform a boost-back instead.

Define "most cases". The higher the staging velocity the better is fly back.

Not at all and the thesis you cite in fact points that out. The higher the staging velocity the further down-range the booster will reenter and the harder it is to flyback, and the more the booster mass grows. (Page 27 figure 22) "Optimal" is around Mach-6 and the highest is only a bit over Mach-8. The same figure points out that the maximum for glideback is about Mach-3.5, while the optimum for boostback only a little over Mach-4. Meanwhile 'real-world' data from SpaceX flights shows boostback staging working well for a NON-winged vehicle at speeds around Mach-6. The cited thesis supports what I've been saying and shows quite clearly that when wings and horizontal landing are made a requirement the operational environment becomes highly constrained.

quote author=RanulfC link=topic=39389.msg1524499#msg1524499 date=1461776612]
And if you're boosting back, even "partially" you need less lifting capability to do so and again it all comes down to the trades being done.

Then why lifting capability at all? Do it like SpaceX/Blue Origin.[/quote]

The simple answer is the trades for the proposed design require it. (An ARPA requirement is some cross range for the booster, which I might point out is the main reason neither SpaceX or BO are interested in the XS1 program) A more complex answer is that neither SpaceX nor BO NEED much cross range but that is a specific operational decision they have made and others to not feel constrained to make the same decisions and assumptions. A simple example is that if a SpaceX or BO booster has errors in the trajectory beyond a VERY narrow range during landing they get blown up or safety purposes where as the Masten booster has the ability to correct those errors with hyper/supersonic maneuvering prior to the landing maneuver. Lastly the more "lift" a vehicle has during reentry the more it can regulate the factors like G loading and heating during the reentry maneuver. Neither the SpaceX or BO designs have any control OTHER than propulsive for these factors as they are purely ballistic vehicles and again this is a difference in design and operations decisions in which neither is "wrong" or "right" in any context as they are decisions directed by the companies involved.

Randy

[TrevorMonty]

The Masten design looks a lot like ESA IXV, which is capable of LEO reentry speeds.

https://en.m.wikipedia.org/wiki/Intermediate_eXperimental_Vehicle

I don't see this vehicle being used as SSTO. But it does give DARPA a very useful reuseable test vehicle, this maybe reason for Mach 10 requirement.

[RanulfC]

The Masten design looks a lot like ESA IXV, which is capable of LEO reentry speeds.

https://en.m.wikipedia.org/wiki/Intermediate_eXperimental_Vehicle

I don't see this vehicle being used as SSTO. But it does give DARPA a very useful reuseable test vehicle, this maybe reason for Mach 10 requirement.

As I understood it the Mach-10 requirement was both experimental, as well as operational since Mach 10 staging makes for a really small upper stage allowing for one that might fit into a payload bay on the booster. (Yes, that's a 'thing" as the military like the idea of 'minimum-mass,' non-aerodynamic upper stage concepts either partially or fully enshrouded on the booster)

Randy

[RanulfC]

Oh and in case folks missed the connection, the Masten design is VERY similar to the 'evolved-DC-X' concepts that were being tossed around as boosters for the "Hot Eagle" concepts

Randy

[TrevorMonty]

The Masten design looks a lot like ESA IXV, which is capable of LEO reentry speeds.

https://en.m.wikipedia.org/wiki/Intermediate_eXperimental_Vehicle

I don't see this vehicle being used as SSTO. But it does give DARPA a very useful reuseable test vehicle, this maybe reason for Mach 10 requirement.

As I understood it the Mach-10 requirement was both experimental, as well as operational since Mach 10 staging makes for a really small upper stage allowing for one that might fit into a payload bay on the booster. (Yes, that's a 'thing" as the military like the idea of 'minimum-mass,' non-aerodynamic upper stage concepts either partially or fully enshrouded on the booster)

Randy

So this vehicle can do multiple roles.
1) RLV for small upper stage and with small satellites staging at mach 10.
2) RLV for larger upper staging at  <Mach 10.
3) RLV for deploying experimental vehicles at hypersonic speeds.

I can see NASA also finding use for it as 3).

Masten would most likely be responsible for operating and maintaining a XS1 for DOD. This would give them a regular income, while still operating their own vehicles for commercial purposes.

[Oli]

You might want to read the whole thing and especially the discussion and conclusion section again. Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage.

I never said Mach 3 staging is not marginal, it's the delta-v you save from glide back that is not marginal.

Not at all and the thesis you cite in fact points that out. The higher the staging velocity the further down-range the booster will reenter and the harder it is to flyback, and the more the booster mass grows. (Page 27 figure 22) "Optimal" is around Mach-6 and the highest is only a bit over Mach-8.

I said "The higher the staging velocity the better is fly back.", that means compared to other methods fly back does better at higher staging velocities.

[joema]

....Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage...

That's correct, as can be seen in this graph I annotated of ideal staging velocity of two-stage launch vehicle vs gross liftoff mass. From "Propulsion and Staging Considerations for an Orbital Sortie Vehicle (Stengel, 1987). Overlayed are the data points for a Mach 7 vs Mach 12 booster. If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

This is counter intuitive since it feels like an air launch or any kind of initial modest boost would help a lot. But what it produces is a gigantic upper stage which in turn requires an even more gigantic reusable lower stage to lift.

https://photos.smugmug.com/photos/i-nKLmZSR/0/O/i-nKLmZSR.jpg

[Elmar Moelzer]

If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

Isn't the Falcon9 staging at about Mach 6 when they do RTLS?

[TrevorMonty]

....Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage...

That's correct, as can be seen in this graph I annotated of ideal staging velocity of two-stage launch vehicle vs gross liftoff mass. From "Propulsion and Staging Considerations for an Orbital Sortie Vehicle (Stengel, 1987). Overlayed are the data points for a Mach 7 vs Mach 12 booster. If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

This is counter intuitive since it feels like an air launch or any kind of initial modest boost would help a lot. But what it produces is a gigantic upper stage which in turn requires an even more gigantic reusable lower stage to lift.

https://photos.smugmug.com/photos/i-nKLmZSR/0/O/i-nKLmZSR.jpg

Are these figures for expendable or reusable booster?.