Posted on 09/06/2022 5:02:31 PM PDT by BenLurkin
Hydrogen is extremely useful as a rocket fuel. It’s readily available, clean, lightweight, and, when combined with liquid oxygen, burns with extreme intensity.
To keep it from evaporating or boiling off, rockets fueled with liquid hydrogen must be carefully insulated from all sources of heat...venting is necessary to prevent the tank from exploding..liquid hydrogen can leak through minute pores in welded seams.
When tanking SLS, the sudden influx of cryogenic hydrogen causes significant changes to the rocket’s physical structure. The 130-foot-tall (40-meter-tall) hydrogen tank shrinks about 6 inches (152 mm) in length and about 1 inch (25.4 mm) in diameter when filled with the ultra-cold liquid, according to NASA. Components attached to the tank, such as ducts, vent lines, and brackets, must compensate for this sudden contraction. To achieve this, NASA uses connectors with accordion-like bellows, slotted joints, telescoping sections, and ball joint hinges.
But hydrogen—the smallest molecule in the universe—often finds its way through even the tiniest of openings. The fuel lines are particularly problematic, as they cannot be hard-bolted to the rocket. As their name suggests, the quick disconnects, while providing a tight seal, are designed to break free from the rocket during launch. This seal must prevent leakage under high pressures and ultra-cold temperatures, but it also needs to let go as the rocket takes flight. On Saturday, a leak in the vicinity of the quick disconnect reached concentrations well beyond the 4% constraint, exceeding NASA’s flammability limits. Unable to resolve the leak, NASA called the scrub.
That NASA has yet to fully fuel the first and second stages and get deep into the countdown is a genuine cause for concern. The space agency has dealt with hydrogen leaks before, so hopefully its engineers will once again devise a solution to move the project forward.
(Excerpt) Read more at gizmodo.com ...
Yeah, I know about that first hand. A $100m that is going to turn into 1b in waste. Totally avoidable.
For Saturn V, See #29.
For Challenger: A politically driven decision to launch outside SRB launch parameters and IN THE FACE OF PLEAS FROM ACTUAL ENGINEERS NOT TO LAUNCH doomed Challenger. "Gottagetthereitis" on the part of politically motivated NASA administration killed the Challenger crew. "Gottagetthereitis" in aviation generally is deadly. It had nothing to do with LH2.
Rocketdyne developed the F-1 and the E-1 to meet a 1955 U.S. Air Force requirement for a very large rocket engine. The E-1, although successfully tested in static firing, was quickly seen as a technological dead-end, and was abandoned for the larger, more powerful F-1. The Air Force eventually halted development of the F-1 because of a lack of requirement for such a large engine. However, the recently created National Aeronautics and Space Administration (NASA) appreciated the usefulness of an engine with so much power and contracted Rocketdyne to complete its development. Test firings of F-1 components had been performed as early as 1957. The first static firing of a full-stage developmental F-1 was performed in March 1959. The first F-1 was delivered to NASA MSFC in October 1963. In December 1964, the F-1 completed flight rating tests. Testing continued at least through 1965.[2]
Early development tests revealed serious combustion instability problems which sometimes caused catastrophic failure.[3] Initially, progress on this problem was slow, as it was intermittent and unpredictable. Oscillations of 4 kHz with harmonics to 24 kHz were observed. Eventually, engineers developed a diagnostic technique of detonating small explosive charges (which they called "bombs") outside the combustion chamber, through a tangential tube (RDX, C-4 or black powder were used) while the engine was firing. This allowed them to determine exactly how the running chamber responded to variations in pressure, and to determine how to nullify these oscillations. The designers could then quickly experiment with different co-axial fuel-injector designs to obtain the one most resistant to instability. These problems were addressed from 1959 through 1961. Eventually, engine combustion was so stable, it would self-damp artificially induced instability within one-tenth of a second.
Aerozine/Nitrogen Tetroxide is a rather rare combination for rocket fuel. And be thankful for that. They’re both really nasty chemicals.
Titan used it, and some Russian rockets use(d) it.
The most common booster propellant combo is RP1/LOX.
Surely you jest.
Lighten up Francis!
I can see that you are upset that the jobs program for nerds cannot get anything done. Don’t take it out on me.
Of course, and don’t call me Shirley.
Not a problem, sir. Eschew making moronic comments and you will be fine.
Yes, it is nasty stuff. Whatever you call it.
One whiff in the lungs turns it to nictric acid.
I saw footage of the Shuttle landing at White Sands Missile Range (WSMR), They had a big fan on a truck that blew wind over Shuttle of a long time before they were allowed to exit the vehicle.
I lived in NM from 1972-1986, many of my Ham friends worked at the labs, military bases or NMSU.
Great bunch of engineers, electronic technicians and physicists.
This making me think all those stories of the moon landing being fake are true.
OK!!!
The fuel part of that mixture is hydrazine and/or monomethylhydrazine and/or unsymmetrical dimethylhydrazine. “Aerozine 50” is a 1:1 mixture of (I forget which) two of those. Hydrazine generally will just kill you. Supposedly, if you smell it you’re already dead ... Or so they taught me in a range-safety briefing eons ago. The hangar had a hydrazine alarm: You hear it, you drop everything and GTFO.
Dinitrogen Tetroxide is the stuff that turns to nitric acid on contact with moisture. Like, as you noted, the lining of your lungs.
The mixture is “hypergolic”, which is to say that it ignites spontaneously on contact.
Both chemicals are liquid at reasonable temperatures, and are therefore very storable. That makes them good for reaction control systems, the small rocket engines used by spacecraft for orienting themselves. Shuttle burned a bunch of the stuff to orient itself for reentry, that’s why they had the big fans on it after landing. Even a little contamination is bad.
The stuff was used by both USA and USSR for ballistic missiles on account of it being storable. You could keep a fully fueled Titan ICBM in its silo for a long time, with no worry about either oxidizer or fuel boiling off. USSR used it in several systems, including the “Scud” IRBM and its derivatives, and IIRC at least one family of their submarine launched missiles.
Solid rockets are much safer to store and deploy ... ;’}
Wasn’t the upper stage of the Saturn 5 moon rocket liquid hydrogen fueled? Apparently the technology of 50 years ago overcame those issues
Saturn V used RP-1 basically kerosene and LOX. The problem with liquid hydrogens is that it is really really cold and very dangerous to test. For LOX you can always test with LN2 which is at a similar temperature and is non-explosive.
I makes you wonder... I have a lot more doubt than I did a few ago.
I think its funny that our most sophisticated manned space vehicle (the space shuttle) was (excluding the boosters) essentially steam powered.
You are talking about hot stuff?
I’m half way through some leftover home made Hatch Red Chili Enchiladas (I made the sauce and froze it). And some hominy that I grated dried habaneros on top of it. The grater that I use is one of those super fine graters.
I appreciate the best Mexican Food in the World.
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