History is full of decisions that if I
had gone a different way could have given us quite a different outcome today
and space history certainly has its fair share of those. As part of NASA's quest
for a replacement Space Shuttle it embarked on a project that looked as if
it could bring a groundbreaking combination of technologies that would
make the original Space Shuttle look like a 1970s trim phone compared to an
iPhone X. But in a decision that was as dogmatic as it was controversial the
project was cancelled when 95% of the components had been fabricated, tested,
delivered and even a new launch facility had been built. The project was the x-33
and was revolutionary on many fronts, it was designed to be fully reusable like a
plane, it would be much cleaner than the shuttle as it would only use hydrogen
and oxygen for both for the main engines as well as the thrusters and wouldn't use
any solid rocket boosters. It could be remotely controlled and take off
vertically and land on a normal runway much like the space shuttle but unlike
the shuttle it was designed to be easy to maintain and dramatically cut the
amount of time, resources and people required to launch and then turn it
around for the next flight and thus cut the cost of getting each kilogram of
payload into space from $20,000 to $2,000. The roots of this design would
come from a previous x-plane project called the national space plane or the X-30 which itself can be traced back to the X-20 dinosaur in the early 1960s.
When Ronald Reagan was elected in 1980 his administration was looking at the
Soviet nuclear threat and what they could do to counter it. In 1983 Reagan
announced the Star Wars initiative but what soon became clear was in order to
build a space shield hundreds of new satellites would need to be placed into
orbit. The problem was fast becoming clear to the US Air Force was of the
maintenance schedule of the Shuttle would not be able to keep up with the
amount of hardware that will be needed to be placed in orbit so they were
looking at additional ways to deploy their hardware. From 1982 to 1985 a
secret DARPA project called 'Copper Canyon' was set up to look into the
viability of a single-stage-to-orbit reusable space plane that would use an
air-breathing engine, be able to take off fly to space, deliver its payload and
then land back on a normal runway much more like an airplane than a rocket based
to shuttle. In 1990 this eventually became the x30 project however this was
cancelled just three years later in 1993 before a single prototype was ever built
because the technology required to make it work was found to be many more years
away than expected. NASA however continued its research into a
replacement for the shuttle and in 1994 it requested proposals from the
aerospace industry to come up with designs for a single-stage-to-orbit
vehicle. There would also be a change as to how NASA would operate the new system. Instead of owning and operating the new spacecraft like a shuttle, NASA would
purchase flights from the company that developed the winning system, this meant
that the commercial companies they would be renting the craft rather than
just selling it to NASA. Three companies replied McDonnell Douglas, Rockwell
aerospace and Lockheed Martin. Of the three designs for Rockwell one was pretty
conservative and was basically an updated remake of the Space Shuttle. The
McDonnell Douglas design the DC-X looked like has come from the set of Buck
Rogers with a vertical takeoff, a lifting body design and vertical landing with
four legs that dropped from the corner of the vehicles base. It was a
strange-looking beast but it worked and it had been flight tested it would also
go on to serve as the inspiration for the Blue Origin New Shepard and several
of the key engineers that worked on the DC X would go on to work for Blue Origin.
The most ambitious design was that from Lockheed Martin, this pushed the envelope not
only in its design but also its chosen propulsion and also construction.
Lockheed Martin won the contract which was worth about $1 billion to
produce a 53% scale flight demonstrator something but commentators of the time
said was an incredibly low price to bring together an all-new vehicle,
however if it was successful it would then be made into a full-scale
commercial version called the 'VentureStar' The Lockheed design would use
aerospike engines first developed by Rocketdyne in the 1970s but as yet still
not flight tested. It would not use any boosters or external fuel tanks like the
shuttle so it would have to be very light with the empty weight being no
more than 10% of the fully laden weight. This would mean on landing it would be
able to use a runway as short as 8000ft much shorter than required
for the shuttle and increasing the possible number of landing sites.
It would also have a lifting body, that means that the body of the spacecraft
can generate his own lift without the need for wings like the Space Shuttle.
Because of the greater surface area of the body it would re-enter the
atmosphere more gently and generate less heat allowing for the use of an all-new
thermal protection system made up of metallic tiles. These were developed by
BF Goodrich and made from Inconel, a heat-resistant nickel-chromium based of
superalloy which was first developed for the SR-71 blackbird. These will be
screwed to the body structure using mounting brackets, this change alone
would save an estimated 17,000 men hours of checking and replacing the ceramic
tiles on each flight of a space shuttle. But the most controversial element of
the design was that of the main fuel tanks which would also be the structure
of the body, it was almost like a giant flying fuel tank and this would be its
Achilles heel. The fuel tanks one for the liquid oxygen in the front and the
two liquid hydrogen ones on either side at the rear
would be made from a carbon composite material which was meant to be lighter
and stronger than the aluminium tanks and this is where things started to unravel.
The choice of composite instead of metal was meant to be cheaper to make but
engineers and designers knew that it was going to be a big problem. They were
trying to make a new fuel tank to hold pressurized liquid hydrogen with hollow
honeycomb walls. There was in fact so much resistance from the engineers that
they forced the management to allow them to build Aluminium Lithium tanks in the
same way as they did for the space shuttle. When it came to the testing of
the first composite tank, it failed the pressure test as the material De bonded.
air was getting into the honeycomb walls and was liquefying, forcing the composite
to break apart. Engineers had anticipated this and had a solution to fill the
honeycomb with closed cell foam but this would add an additional 500kg of
weight to the rear of a craft. Then another problem showed up the aerospike engines needed to have larger than expected exhaust ramps to allow them to
cool correctly. These ramps were made from a heat-resistant heavy copper alloy
called Narloy-Z, so now the engines would also be adding extra weight to the rear
of a craft. This extra weight at the rear would make the lifting body unstable
without a major redesign something that would cost a lot in both time and money.
The problems with the composite fuel tanks were in danger of stopping the
whole project so the engineer's asked to fit a standby aluminium fuel tanks. These
had passed the pressure testing and ironically turned out to be slightly
lighter than the composite ones so things were looking OK as this would
also help offset the engine weight issue. NASA had chosen for Lockheed designed
because it was A) a very low bid and B) it was to introduce a range of new and
untested technologies in one project. This was a high risk approach but if it
worked it would be a game-changer for launch vehicles. However there was one more problem that would prove to be the killer blow to the
entire project. In 2001 the NASA director at the time Ivan Bekey was to appear in front of a Subcommittee on space and Aeronautics at the US House of Representatives for a funding round. In a speech that stunned
the workers on the project, he said that the X-33 project must use the composite
fuel tanks as this was key to testing the interaction of all the new
technologies in real-world flight tests. To use the aluminium tanks instead of
the composite ones which would be the structure of a craft and where the new
thermal protection system will be mounted to would make the whole point of real-world testing invalid he said. With this the X-33 was effectively doomed
without extra funding for the development of the composite fuel tanks
something both NASA and Lockheed Martin disagreed about who should pay.Now some might say why not take a more pragmatic approach and build with aluminium tanks
to test it and then change over to the composite when the technology had
advanced enough, the reply to this was that because the VentureStar was to be
privately funded, if it were to go ahead with the aluminium tanks it would be
confirming that the technology was simply too difficult to do and maybe the
whole project was overreaching itself on the technology front and that would make
funding almost impossible to find. With this impasse on the side of the
management the project was canceled in 2001 and all the new technologies and
hopes of a brave new future for reusable vehicles went with it.
In 2004 Northrop Grumman who have been working with NASA announced that they
had solved the problem of the composite fuel tanks after they had used a new
manufacturing technique and they had successfully been tested over 40 times
over a nine-month period and they made them 25% lighter than the aluminium ones.
There were several attempts by the US Air Force take on the project and make the VentureStar their own, they had plans to
have it fully usable by 2012 but each time they tried it was denied at the
highest levels of government leading some to say that it was a political
decision and that Dick Cheney was not going to let a project set up by Al Gore
back on the books. No part of the X-33 technology would be used for the new
upcoming SLS system which was to use traditional disposable rockets in much
the same way as Apollo had done 50 years earlier. NASA has acknowledged that it
made fundamental mistakes and was simply trying to do too much with too little
funding on a high-risk project, which with a little greater forthought and
funding could have given us a revolutionary new space shuttle and
probably changed the way we access space. If you're interested in finding out more
about the aerospike engines, we have a video about those and I'd also like to
thank our patrons for their ongoing support and please check out some of our
other videos. So for now I'd like to say thanks watching and please subscribe,
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This channel has a video on soul transfer
I'm only a minute in, but y'all realize that the big mistake wasn't the cancellation, right?
Edit:
While flying that thing as a tech demo would have been educational, it never had a future as a low cost space transportation system. A lifting body SSTO is not a practical choice. The problems with the fuel tanks could have all been solved if the vehicle did not have a lifting body shape.
Re-entry on a cylindrical stage is very possible, but because there is no lift it just has a small cross-range.
SpaceX and Blue will get this right.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
7 acronyms in this thread; the most compressed thread commented on today has 17 acronyms.
[Thread #205 for this sub, first seen 16th Jun 2018, 18:22] [FAQ] [Full list] [Contact] [Source code]
The X-33/VentureStar is doable now with new high strength but lightweight metals used instead of carbon composites for the tanks. These new metals would even beat the original specifications for the tanks. Note this means the VentureStar now becomes viable as an SSTO:
http://exoscientist.blogspot.com/2018/06/darpas-spaceplane-x-33-version-page-2.html
I wonder how advanced and livable this country would be if we scrapped political parties and instead put our country and soicity first.