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New Shuttle Fuel Tanks Ready
confusion writes "NASA has completed the redesigned fuel tanks for the Shuttle scheduled to for launch in May or June of this year.
"On the new tank, NASA has reconfigured the struts and fittings where foam was prone to peeling off, and installed heaters to prevent ice from forming. The new tank has cameras that will allow ground workers to monitor for damage as the shuttle ascends.""
Sort of... An EVA would be too time consuming and expensive. However, when the shuttle approches the ISS now, it's going to flip 360 degrees so the station cameras can get a clear veiw of the entire shuttle and check for damage. I read it somewhere on the JPL site.
They're so soft you could problably crush a piece with your hands, which means they're easily damaged during flight (and we've seen the fatal results of that) Errr...it was an impact against the leading edge of the wing -- which is covered by reinforced carbon-carbon -- not the ceramic thermal tiles.
We have put nuclear reactors into orbit before. On one of the missions, the rocket even blew up. The net gain in radioactivity? ZERO. The casing around the material was designed to be able to tolerate a rocket explosion. They recovered the material (every last gram) and reused it on a later mission. The problem is not garunteeing a 100% success rate, the problem is making sure that if something does occur, that the material doesn't get spewed all over the contry side. And that is orders of magnitude easier.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
Only a few critical tiles on the leading edge have to be there or you're screwed. All you really have to do is carry exact replacements for those. For the others, you have to lose several tiles before there's a significantly increased risk, and even if you do, they don't have to be exactly perfect fits. They just have to protect against -most- of the heat.
They're basically a really heat-resistant glass. For non-edge purposes, cut a few that are slightly bigger than they need to be and carry sandpaper. Sure, that's good for a few hours of work, but what else are you going to do while you wait two weeks for the rescue shuttle to be prepped for launch?
Check out my sci-fi/humor trilogy at PatriotsBooks.
That's funny, because I seem to remember the most likely theory on the disaster was the foam hit and punctured the leading edge of the wing which is made of reinforced carbon-carbon (RCC), and not the heat resistant tiles (which are designed so a few can be lost during normal flights anyway).
"Truckers check their brakes before a big hill, why don't astronauts check the heat shield?"
There's rarely any doubt about the trucker's ability to get back into the cab after doing said walkaround. Going EVA is risky enough in the nice enclosed space of the cargo bay, and using an MMU to go much beyond places with easy handholds has been limited mostly to demonstration runs which themselves have been within line-of-sight of the cargo bay. Leaving the cargo bay to inspect other surfaces of the orbiter, especially the undercarriage, not only affords you with no places you can hold on to but instead offers plenty of places you don't want to touch (like the tiles you'd want to inspect). There's a good chance that inspecting for damage itself would cause damage.
"...a polyurethane foam applied with CFC-11 chlorofluorocarbon, was used on domes, ramps and areas where the foam is applied by hand." (Columbia Acident Investigation Report, disk version)
It was the hand-applied foam that came off. Also, the procedure for applying the foam was not modified as it should have been when CFC-11 ceased to be used on most of the tank. Had it been changed, there shouldn't have been a problem.
BTW: Freon is the term for "refrigerant." There are multiple freons. Sigh.
This sig seemed like a good idea at the time....
Irrelevant.
Troy's bear suit uses FSA 333 ("Fire Suppression Agent 333"). Which he blames for the FBI harassing him and instigating his divorce (no, I'm not kidding - he claims that it is the secret to making extraction of Canadian tar sands cheap, and the US government is after it). It is a fire retardant, heat resistant material.
This is *NOT* what you want on a reentry craft.
You can't just insulate your way to a safe landing; you have to *dissipate* the heat. That is what the tiles are for; they have a huge surface area, and even non-fibrous ceramics are good at radiating heat. As a consequence, you can stick the titles under a blowtorch for an hour if you wanted, take them out, and a couple second later they'll be completely cool to the touch. They dissipate heat that fast. *That* is what you need for reentry; not some "fire suppression agent".
The other major in-use option is ablatatives (again, not what troy invented). Albatives "ablate" (i.e., steadily erode off) as they heat up. As they do so, they take the heat that they absorbed with them. There are also other theoretical or in-testing options being looked at
Seen on a Japanese food processor: "Not to be used for the other use."
RTGs are potentially worrisome, but the fuel can be heavily protected as you mention. However, they are most often used as electrical power generators, not propulsion systems. RTG fuel is nasty stuff even before the RTG is put in use.
Fission reactors (not RTGs) that are not activated until orbit really aren't that much of a big deal on launch because they can be fueled with fresh U-235 which really isn't very radioactive or dangerous until you switch the reactor on and start generating fission products. The only issue is if they don't make it out of earth orbit and eventually the orbit decays. Powering an ion drive with one of these to do missions to the outer planets might make a lot of sense.
The scariest nuclear propulsion case a the high-thrust rocket used for the first or second stage liftoff. These have been successfully tested on the ground but never flown. They basically pack all of the power of a large commercial nuclear plant into a package only a few feet in diameter. They run full blast with little or no shielding. There is no way to heavily shield or isolate the fuel without impeding the huge heat transfer rate that is necessary to propel the massive amounts of propellant gas out the rocket.
These high-thrust rockets operate at the very fringes of material strength capabilities and probably have a high probability of disintegrating, spewing partially spent fuel and waste into the atmosphere. That's one reason that they've never been actually used.
Melting points.
Aluminum - 660 C
Titanium - 1660 C
1. The cameras arent new. Right now, the cameras on the tank are ATM cameras. They couldn't get the new cameras approved for manned space flight in time. These will be installed on future tanks (not the next one delivered, but probably the one after that)
2. Since the tank is actually a super thin aluminum shell with two more super thin aluminum shells inside of it (liquid oxygen and liquid hydrogen at something like -600 F) it needs insulation.
the foam was made to be more sticky and less prone to falling off.
The bipod (where the shuttle's nose connects to the tank) was espically prone to foam falling off of it and hitting the shuttle. So, what they did was put heaters in the base of the bipod to prevent the -600f tank about 2 inches away from freezing the thing solid.
The heaters only run untill just before liftoff, when the umbilical is detached and the shuttle launches.
Those are the two main things (the foam and the heaters) that the review commission required before they could fly again. Everything else is just extra.
Also, the shuttle is the mack truck of the space program. It can only go into Low Earth Orbit, not even into outer space. We need a better system. cspring
At least the cockpit electronics have been upgraded - to 32 bit computers (among others 386). I'd guess that that's just the part the pilots/astronauts interact with, the avionics is probably still the old hardware, which was not 8 bit, but something derived from IBM's S/360 line with 32 bit, but only 104k of proper core memory. If you want to know more, I suggest you read at least chapter four of Computers in Spaceflight: The NASA Experience
Only recently have Pentiums and other processors of the same level been qualified for radiation hardening in space applications (at the manned-spaceflight altitudes, which are full of radiation). The current level of technology has circuit pathways that are too small and are more easily affected by the exposure. (http://www.sandia.gov/media/rhp.htm --> decision to redesign the Pentium was only in Dec '98 and it was expected to take 2-3 years.)
Either way, whatever they eventually design to replace the Shuttle after its decommissioning in 2010 (or shortly thereafter) will likely be designed with 1990's technology.
My motorcycle's stock titanium pipe (excluding manyfold & tubing) costs 1800 CDN.
Titanium is still expensive.
> launching a shuttle when the ambient temps
> were well below the rated range for the SRB
Exactly - it's just like that. Except, the NASA engineers making the decision didn't have the data about the effect of cold on O-rings, while Rutan was quite well aware of the windspeed, and as a longtime aviator, should be very well aware of the dangers of wind shear (NASA routinely cancels launches, at big financial loss, if they think wind shear might be too high).
> I am trying to remember when a fully
> integrated shuttle stack was launched unmanned
> for testing purposes
Unless explicitly stated, all tests were unmanned. Only major tests listed; there were smaller tests going on almost daily. Tests listed for all shuttles being worked on at the time. I've probably left out some major tests, too, but I don't have forever to assemble the list.
Feb 15, 1977: Complete mated ground vibrational tests of airframe
Feb 18, 1977: The first unmanned captive flight of airframe (no engines)
Feb 22, 1977: The second unmanned captive flight (like above)
Feb 25, 1977: The third unmanned captive flight
Feb 28, 1977: The fourth unmanned captive flight
Mar 2, 1977: The fifth unmanned captive flight
Jun 7, 1977: Unmanned fully integrated ground fire test
Jun 18, 1977: First manned captive flight
Jun 28, 1977: Second manned captive flight
Jul 26, 1977: Third manned captive flight
Nov 15, 1977: First ferry flight test
Nov 16, 1977: Second ferry flight test
Nov 17, 1977: Third ferry flight test
Nov 18, 1977: Fourth ferry flight test
Dec 9, 1977: Complete approach and landing tests
Apr 21, 1978: First static test firing
Apr 24, 1978: Precombined systems tests
May 19, 1978: Second static test firing
May 30, 1978: Vertical ground vibrational
May 19, 1978: Third static test firing, 90% thrust
Jul 7, 1978: Fourth static test firing
Sep 20, 1978: Launch configuration vibrational testing
Jan 30, 1979: Start burnout mated vertical ground vibrational tests
Jan 30, 1979: Start orbiter mated vertical ground vibrational tests
Feb 3, 1979: Complete combined systems test
Feb 26, 1979: Complete mated vertical vibration systems test
May 4, 1979: Fifth static firing test (cont'd. Jun 12)
Jun 15, 1979: First SRB qualification firing
Jul 12, 1979: Sixth static firing test (Cont'. Oct 24)
Aug 6, 1979: Complete limit test
Oct 5, 1979: Complete setup and thermal tests
Nov 4, 1979: Static firing
Nov 12, 1979: Complete OMS qualification tests
Dec 16, 1979: Orbiter complete integrated test
Dec 17, 1979: Static firing, full 554 seconds, 100% power output, with proper reduced scaling and gimballing tests
Jan 14, 1980: Complete orbiter integration tests
Feb 14, 1980: Final qualification firing for SRB
Feb 28, 1980: Yet another full length static firing
Mar 20, 1980: And yet again.
April 16, 1980: Static firing again
May 30, 1980: And again
Jun 1, 5, and 16: More tests, this time for Colombia
Jul 12, 1980: Another firing test - and thankfully they did so many, because with how unpredictable rocketry is, they got burnthrough on this one, and were able to know about a potentially lethal problem and had time to rectify it.
Dec 4, 1980: Another static firing
Jan 5, 1981: Emergency egress test (manned)
Jan 17, 1981: Another static firing
Feb 2, 1981: Wet countdown test simulation
Feb 4, 1981: Continue a series of them
Feb 20, 1981: Flight readiness firing
Apr 12, 1981: STS-1 (manned, of course)
Those are the tests on the main shuttle craft. The 1/4 scale model underwent, to some degree, all of the tests listed above, plus full flight tests. Quarter scale models were built of both the SRBs and the orbiter. Needless to say, they were unmanned. They completed testing on Mar 31, 1980.
Here's Rutan's test suite:
A small series of unmated unmanned static test firings; no mated test firings that I am aware of, and I can't find anything online about any.
Seen on a Japanese food processor: "Not to be used for the other use."
> same tech for an orbital launcher ... which is impossible. Polybut/nitrous does not have enough ISP, period. Nitrous tanks are too heavy, period. Unless you mean "completely different tech" when you say "the same tech", you are completely incorrect.
... is not Rutan. Rutan has a rocket joyride company. Yes, he wants to reach orbit eventually, and that's a nice admirable goal. But he has nothing of the sort either on the ground or flying.
> All their engines are simpler than SSME, RS68, etc
And have the performance of a V2. V2s will never reach orbit, either. The extra complexity in SSMEs, RS68, etc, is not for no purpose. Yes, they're not the be-all, end-all of rocketry, but they at least have the *capability to reach orbit with any relevant amount of payload*
> OK, so I might have over-sold the parts count
It was obvious that you had before even reading the article. At the bare minimum, if you want a liquid fuelled rocket to perform well at all, you need a turbopump - pressurized tanks just weigh too much. Even the simplest theoretical design of a turbopump is still a fairly complex beast, and very sensitive to conditions inside the rocket. If I ever get into metalworking, I have a design for a theoretically simpler turbopump that I'd like to try out (an electric reluctance motor-driven one - no driving turbine, no seals in your fuel/oxidizer lines, etc), but even it would still be quite the piece of work, and unless I want to go SSME-style and have it staged, it won't perform as well as engines like SSMEs do.
See how these tradeoffs work? You can't get ISP for free; if you want a cheap engine, you can take a polybut/nitrous engine. If you want an engine that will get you to orbit? Tough, it's not going to happen. The ISP is too low and the tank mass too high. Anyways, back to the TR-106.
Not to mention that this is a LH/LOX engine. Are you aware of the difficulties in working with LH? Hydrogen embrittlement. Uneven boiloff. Insulation application (which has been a pain to NASA as well as other agencies, and one of the reasons why the Russian kerosene rockets, despite their much lower payload fraction, are so cheap). Pressure regulation. Temperature regulation. Hard to ignite when cold. And the obvious issue of the huge bulk size.
BTW, it doesn't have a single pintle injector; it has a single *fuel* injector. How do I know that there will be at least two injectors, ahead of time? Again, it doesn't make sense without that; liquid biprop rockets work by burning fuel and oxidizer. Both enter through "injectors". The more you preheat your fuel and oxidizer, the less complex of an injector you need, but then you need a more complex preheater. See how these tradeoffs work?
About the least "injector" you could get away with would be a simple hole in the combustion chamber attached to your oxidizer line, and you might get away with calling that something other than an "injector", but if you do that, you better have your oxidizer preheated or it'll never mix well.
> not sure how much catastrophic testing they did
As far as I am aware, it was *zero* catastrophic failure testing. They did a nice testing suite of glide tests, but the tests that they made public (and why on earth someone would hide something that makes them look safer - more testing - from the public, would be beyond me...) concerning their rocket engines are little short of embarassing. They did some non-integrated ground static firings, and after that they were firing on a fully integrated craft, midair, with a pilot in the cockpit.
Yeah, they're Square Jawed Engineers. And I admire that spirit, and I know that their test pilot supported them all the way. And the design has the potential to eventually be a very safe, reliable joyride. But I hope that everyone who straps themself into crafts like this know what they're getting into.
> the only manned spaceflight program
> functioning in the US
Seen on a Japanese food processor: "Not to be used for the other use."