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Quaoar wrote:On second thought, it would always be possible to trap metallic hydrogen into some sort of graphene cage (e.g. fullerene) to withstand 10-20 GPa of pressure
Thanks for following up with the graphene cage possibility!
I'd wondered if something like that might be possible,
(th)
When I was a child, I visited with a school trip the central dairy of Rome and I was impressed seeing milk flowing into paper tubes which were transformed in tetra-pack by machines. I wonder if it may be possible to do the same with metastable metallic hydrogen: the diamond anvil synthesizes liquid MMH and makes it flow at high pressure into graphene tubes, which are cut and welded by lasers to form micrometric tetra-packs holding MMH.
More recent works suggest that metallic hydrogen remains metastable down to 20-10 GPa, and quickly decays in molecular hydrogen at lower pressure.
https://aip.scitation.org/doi/10.1063/1.5008406
I don't know it is possible to build a tank able to hold 20-10 GPa of pressure, but anyway it would be too massive for a rocket.
I'm very sad, because I also hoped to see a 1500 s Isp metallic hydrogen rocket.
Errata corrige:
On second thought, it would always be possible to trap metallic hydrogen into some sort of graphene cage (e.g. fullerene) to withstand 10-20 GPa of pressure
This kind of rocket would be similar to a classical LOX-LH2 rocket, but the LH2 is "doped" with a powder of fullerenes filled of metallic hydrogen (e.g. 25% in weight). Small amount of LOX is needed to burn the carbon cages and start the metallic hydrogen decay.
So imagine we have metallic hydrogen fullerenes and let's build the rocket:
chamber pressure 100 bar
area ratio 250
fuel: LH2 with 25% wt of metallic hydrogen
oxidizer : LOX
O/F ratio: 0.1
chamber temperature: 3337 K
vacuum exhaust velocity: 10.1 km/s (better than a solid core NTR but without the trouble related with nuclear)*
Simulation performed with NASA CEA
https://cearun.grc.nasa.gov/cgi-bin/CEARUN/donecea3.cgi
* Note: it is also possible to increment the exhaust velocity by augmenting the metallic hydrogen percentage, but it also rises the chamber temperature. Anyway, we can imagine some kind of vortex cooled chamber, where the reaction is confined in the meddle, which can withstand higher temperature. In this case we can have:
chamber pressure 100 bar
area ratio 250
fuel: LH2 with 50% wt of metallic hydrogen
oxidizer : LOX
O/F ratio: 0.1
chamber temperature: 4450 K
vacuum exhaust velocity: 13.7 km/s
Not as old but important Researchers recover 1-million-year-old mammoth DNA
I'ts very interesting: if we avoid to annihilate each other in a nuclear war, in a near future we will likely able to resurrect the mammoth, by studying the difference between it and an elephant, then engineering an elephant embryo by changing the genes in a way to grow as a mammoth.
More recent works suggest that metallic hydrogen remains metastable down to 20-10 GPa, and quickly decays in molecular hydrogen at lower pressure.
https://aip.scitation.org/doi/10.1063/1.5008406
I don't know it is possible to build a tank able to hold 20-10 GPa of pressure, but anyway it would be too massive for a rocket.
I'm very sad, because I also hoped to see a 1500 s Isp metallic hydrogen rocket.
One point is that some people act afraid of scientists creating a real Jurassic Park. The claim is dinosaurs would cause modern humans or modern wildlife to become extinct. But the conflict between wolves and jaguars vs terror birds, direct descendants of raptors, did not go well for the birds. Dinosaurs would be dangerous animals, that have to be treated with respect. But don't expect them to take over the world. If set free, mammals will dominate, dinosaurs will die. So it is safe to create a real Jurassic Park.
I agree it's safe to create a real JP: actual ecosystems are not optimized to support a mesozoic mega-fauna: in wilderness big sauropod wouldn't have enough plant to eat, so big carnivores like T-Rex wouldn't have big prays to eat
This is "Free Chat". Just saw a documentary about dinosaurs, and re-run of "Jurassic Park". Build up to "Jurassic World" opening this Friday. The documentary said Jurassic Park got a lot right, but some things wrong. For one, the movie depiction of velociraptor was a combination of two real dinosaurs. The real velociraptor was smaller, about the size of a dog. Steven Spielberg liked the name, but wanted something the size of a person. The real dinosaur that size was Deinonychus. The other issue was raptors had feathers. Tyrannosaurus Rex had skin, paleontologists found a skin impression. So that one was correct. But the documentary said the movie even got one detail of Tyrannosaurus wrong: it ran about 16 miles per hour, not as fast as a cheetah. Still, a 10 ton roadrunner from hell. Wikipedia says 18 mph, and 6.8 metric tonnes (7.5 short tons). Meh! Close enough. They found fossils of velociraptor with impressions of feathers. All raptors had feathers. Modern recreation of velociraptor:
http://upload.wikimedia.org/wikipedia/c … noguy2.jpgThis got me thinking. South America had a terror bird before Central America joined north to south. Then animals could migrate between the two continents. Mammal predators migrated south, out competed terror bird. Paleontologists claim that dinosaurs were dangerous, but if birds evolved from raptors, and terror birds of South America survived until wolves and jaguars arrived, then how bad were they? Scientific name for terror birds is Phorusrhacidae:
https://upload.wikimedia.org/wikipedia/ … agliai.jpg::Edit:: The previous image of Phorusrhacidae doesn't show anymore, so replaced by one from Wikipedia.
The velociraptor of Jurassic Park is actually a utahraptor: at the time the utahraptor was not still discovered, but the narrative needed an over-sized velociraptor: they asked paleontologist Robert Bakker who told them to do it anyway because evolution can change the size of an animal very quickly, so it's very likely that an over-sized velociraptor had really existed. Few months after the first utahraptor was discovered (they create it as a big lizard but it was feathered like a bird).
T-Rexs hounted in pack like lions: the young specimen were nimble and faster: they chased the prays driving them where the slower but more powerful adults lurked in ambush
For Quaoar re #1875
Picking up on your point about education and respect for the rules .... While I don't have hard data to work with, I have the impression funding for civics classes has been reduced in American schools as the pressure of expense causes budget adjustment. As Americans try to address the many issues revealed by the current situation, restoration of education in how the Constitution is supposed to work might be worth considering.
(th)
It happened even in Italy: every government who takes office does first thing public instruction and health-care cuts. That's why we have a lot of uneducated people unable to understand how to correctly wear a mask and consequently more than 2,300,000 confirmed cases of covid-19 and 81,800 deaths, and we are in good position to win the silver medal in that sad European championship.
Quaoar:
Your perception is quite correct. Amazingly (or disappointingly), many Americans do NOT understand those points you made. Instead they believe the election fraud lie.
GW
Hi, GW. Happy to hear you.
I had a scientific training, so I'm used to look for hard evidence and I know that extraordinary claims need extraordinary evidence.
What is happening is vary sad.
It seems US people are split in two, and the two halves hate each other. In Italy is almost the same and TV debates, where politicians only traded insults without saying noting of constructive, are the new normal now. Call me old-fashioned, but I think that formal education and respect of the rules are essential for a civil society, regardless of our political orientation.
Here are a few things that come to mind. There was a great deal of postal vote fraud. Large numbers of dead people voted through postal votes, exclusively for Biden. Some of those that voted were old enough to have fought in the civil war! Many postal votes were also found to have been binned (mostly those for Trump). There were statistical irregularities that could only have resulted from fraud. Some districts containing thousands of voters, did not produce a single Trump vote when counted. There were oddities in the way that the votes were tallied using the dominion machines, with sudden dramatic swings towards Biden, with no such swings visible in the other direction. How could that happen without software manipulation or binning paper votes for the other side? There is the fact that the counting machines were designed to fiddle votes in the first place.
The vote counting was deliberately opaque, with windows boarded up and republicans barred from the count. In spite of all of this, state and supreme courts repeatedly refused all requests for investigation. The full extent of the crime was therefore covered up. Trump may indeed have won the election were it not for fraud and I think he can justly claim to have been cheated. But nothing can be proven because investigation was refused at every turn.
You need to consider the danger perception bias: reds, who are more prone to consider the epidemic a hoax, have no fear of covid-19, so they mainly voted in the presence, while blues, who fear the virus, preferred to vote by mail. This bias can explain the difference between red and blue votes in the polling stations and in the mail ballots without the need to assume a fraud.
The constitution includes the right to bare arms precisely to allow the American people to remove a tyrannical government by violent revolution. The US now appears to have exactly the sort of government that the founding fathers had in mind. It won an election by cheating, using counting machines which contain embedded software specifically designed to twist the vote. It benefitted from absentee voting, which was prone to corruption. A large number of dead people apparently voted for the incoming administration. This isn't a hunch or a suspicion, it definitely happened. It is also benefiting from a technocratic elite which deliberately silences contrary political opinions. That is the direct opposite of democratic forum.
The normal checks and balances failed; the judiciary and Supreme Court failed to order an electoral investigation, even after the evidence of vote fraud was overwhelming. In doing so, they legitimised cheating and essentially destroyed democratic government in the US forever. From now on, government rules without the will of the people. If it loses an election, what is to prevent the losers from cheating to stay in power? They need never lose an election again.
America's fate would appear to be sealed. There is no way out now. And the policies of the incoming administration will push up national debt rapidly, degrade the value of the dollar, add millions of hostile foreigners to America's population and make America a slave to an arrogant corporate elite on one side and the Chinese communist party on the other. All of these things will hasten America's decline.
The losers in this election are the American public. Already Biden is planning a domestic terrorism bill, designed to degrade freedom of speech and the right to bare arms. It will make the people slaves to the state. The Democratic National Party are Marxists. Marxists do not value human freedom. They believe in identity politics, absolute control, ideology and the grandeur of the state. Little people are just things in their way. That is exactly how they behaved in the last election. The incoming administration is conspiring with corporate interests to undermine the rights of the American public. They see public opinion as a threat to their priorities and something that should bend to their will, rather than the other way around. GW Johnson apparently thinks they are decent people and that efforts to silence the desent are justified. How can he possibly think the way he does? However clumsy and inept Trump may be, his opponents are clearly evil.
This has come to pass and people here worry that an angry crowd stormed a building? You need to get some perspective. This is a turning point in history. It marks the point where the will of the state irrevocably diverges from the will of the people. When future historians study the fall of the American Republic, the 6th January 2021 will be a landmark in history, right up there with the October Revolution. It marks the point where a 240 year experiment in democracy finally came to an end.
Calliban, I'm neither a Democratic nor a Republican, I'm only an Italian who is trying to understand what is happening in US.
In the 2016 election Mrs. Clinton get a little more votes more than Mr. Trump, but Mr. Trump won due to the arrangement of electoral colleges. So Blues and Reds are almost half and half and there is a few percent of swing voters who shift the balance sometimes for the Dem candidate and sometimes for the Rep candidate.
If this election had hold in November 2019, when US economy was good and the epidemic didn't still erupted, likely Mr. Trump would have won. But he didn't manage the epidemic very well, and the economy went wrong, so it seems to me quite likely that the swing voters have turned to Mr. Biden.
Assuming that mail ballots are opaque and easy to cheat - I don't know if it's really so because I never vote in US - but having no evidence of cheating, I'm interested to know how can you be so sure that Mr. Trump has won and the election was stolen.
Water boils @ 81.01°C = 177.88°F at 18,000 feet.
Why not to use a pressure cooker?
We Italians use it when we want to make a good spaghetti in the Alps.
So, Twitter suspended Trump's account. That's a violation of the First Amendment.
In the former Soviet Union there was the Communist Party who established what you can say and what you can't, in western democracies there are Facebook and Twitter who play this role. In USSR you could be executed by a firing squad or interned in a gulag, in current US and Europe, if your posts are non politically correct, you can be banned from Facebook and Twitter, which means almost a civil death sentence. That's intriguing: it remembers me the difference between George Orwell's 1984 and the non-violent totalitarian regime of Aldous Huxley's Brave New World.
I would agree zoning and approval boards have to much power on how you can use your land. Then again that's a bad neighbor.
Someone might be led to think that private property is only an illusion and the states are the real owners of everything, like in the former Soviet Union.
Hi to all,
Seeing the 6th January events from Italy I was very saddened to see a big democracy like US in this troubles.
During his four-year term, President Trump did something very well, like not starting wars, and something really bad, like the management of the epidemic (politicizing the use of the mask was the dumbest thing of all), but in his final days he really made a political suicide.
Likely, everyone of us, at least once in his/her life, suffered some kind of injustice or has been deprived of a deserved victory in a competition. But we all know this simple rule: no evidence = shut-up. So, even if the claims of electoral fraud were real - I know very little of American ballot system to express an opinion in this regard - having no evidence of fraud, President Trump would have been silent, followed the rules of democracy and accepted the loss to not inflict damage to the Country he has sworn to protect.
Instead, his behavior seems to me that of a six years old spoiled kid, whose parents used to always make him win, the first time he faces a real play: unable to cope with a loss, he flares up like a red dwarf star and flips the board over.
For Quaoar re #12
First, thank you for your detailed (and information rich) reply!
There is a chance the young gent I have in mind to help with English translation is "listening", so I will merely try to encourage him to contact you.
Because this topic is highly specific, I will honor the tight focus by opening a new topic about ES, which you have (kindly) offered.
Regarding the tank shelter idea.... It should be possible to measure the performance of the shelter mathematically. The most worrisome projectiles to be addressed are iron atoms without electrons moving at close to the speed of light.
There are numerous references to these interesting objects in the forum. A member named JOSHNH4H invested some time thinking about them, and there is at least one post about a research facility where they are studied on Earth using a purpose built detector.
The desirable state (from my perspective) is a total influx of ZERO charged particles of sufficient strength to injure a living creature. I'm not sure about free flying neutrons, but I assume they are present in the cosmic soup.
The question to be answered is how effective the shelter you have proposed would be. It should be possible to devise a software model that would provide a reasonable level of certainty about the performance of your design. Alternatively, there may be a National agency that would be willing to fund an actual experiment on an actual outpost, well away from Earth and therefore in harm's way.
(th)
20 g/cm2 of kerosene cannot stop 2 GeV protons and heavy ions of GCR, but the GCR background is not a problem in a less than three months travel in the inner solar system: its only task is to stop the 200 MeV protons of solar mass ejections. A years-long travel in the outer solar system will probably need some kind of GCR shielding like superconductive coils magnetic shielding or ES, but the spaceship of my book has only to go to a wormhole at 0.85 UA from the sun, where a Hohmann transfer takes 161 days.
For Quaoar re Science Fiction project ...
The premise of your story is interesting, and the physics seems (to my impression anyway) as well within the range of Science Fiction of the Analog level, which is where my focus has been for a while.
The only plot element that is going to require reader acceptance is the worm hole, and by now most readers should accept that and just go with the flow from there. (th)
I like realistic "hard-fiction" but interstellar travels are impossible with current technology: a wormhole in the solar system is a trick that allow me to travel between stars with Hohmann orbits and NERVA-derived NTRs.
By any chance, are you interested in considering a collaborator to help with dialog? (th)
I surely will need some help for the dialogs when I write the English edition. By now I've just finished the first two books of the saga in Italian, but I haven't published them because in the next books I'll probably have to go back and change something to make ends meet.
In your case, the plot element of building the technology at a level which can be accepted by the average (science fiction) reader is attractive (again, to my point of view).(th)
I use very simple technology: a modular spaceship with 9 vapor-core NTR (1000s Isp 415 kN of thrust) and a magnetoshell for areo-magnetic capture at both ends (https://www.nasa.gov/directorates/space … netoshell/) (otherwise mission delta-V would be prohibitive even for a nuclear spaceship), and a SpaceX Starship-derived habi-lander with control winglets and 24 Merlin landing rockets on the belly. After landing the characters travel on the planet mostly via vintage flying-boats with hydrogen turboprops.
Edit#1: As far as radiation shielding is concerned ... The use of electrostatic shielding is an idea that goes back to the 1970's. I've reported to this forum on that work, elsewhere in the forum archive. If you're interested, I would be willing to look for the posts where that information is recorded.(th)
ES needs a very high positive voltage to stop protons and strong magnetic fields to deflect electrons accelerated by the positive electrostatic fields: the hardware mass is more than a storm cellar surrounded by 20 g/cm2 of kerosene, which is also needed as landing propellant.
Edit#2: Your skill with English is obvious, so I am assured you are able to use at least two languages fluently. The audience for your work will be increased by the number of languages in which it is offered.
Do you have other languages on tap as well?
(th)
I also speak some broken Japanese, but I can write fluently only in Italian and English
Um, well, you asked advice from those on this forum. And you asked if the same could be done with cryogenic propellants like L-CH4.
Liquid hydrogen boils at -252.78°C, spacesuit temperature in Earth orbit is ±250°F, +121°C to -156.67°C, but usually represented as +120°C to -150°C. So with moderate pressure and carefully shading the tank, you can keep LOX and LCH4 liquid. Transit to Venus will be warmer on the sun side, but the same on the dark side. This means LH2 requires active refrigeration.
LOX and RP-1 remain liquid at different temperatures. If your ship uses LOX, it may as well use LCH4. Apollo SM main engine used N2O4 and Aerozine 50, a 50:50 mix by weight of UDMH and hydrazine. Both Apollo propellants remained liquid at room temperature, so temperature control during transit wasn't an issue. LOX/LCH4 has higher Isp and safer.
You said your mother ship will use vapour core nuclear, then why not use that for the lander? Especially if you use LH2 propellant. An open cycle gas core nuclear thermal rocket was estimated at 6,000s Isp in the 1960s; later designs estimate up to 9,000s. At that Isp, an SSTO in 1.3 G could work. Don't know how much radiation would contaminate the landing zone. An alternative is a winged lander. With a lifting body, you could land on a dry lake bed like Shuttle. Take off with a jet engine to get away from habitation before igniting the OC GCNTR.
Thank Bob, the documents you have posted about Starship are very usefull and interesting.
The problem of my habi-tank is that the landing propellant has to be used as screening mass during the 180 days of travel Earth-wormhole (at the exit of the wormhole we are in the system of a red dwarf, so the transfer orbit to the super-earth is only 9 days.) RP1 is liquid at room temperature so we can build a double wall tank with the storm-cellar surrounded by the propellant. I don't know if refrigeration systems can allow a 48-people storm cellar surrounded by 20 g/cm2 liquid CH4, without boiling the propellant of freezing the people.
They cannot use a gas core NTR because in my novel is set in a near future (2220), where humanity is in decline, coastal towns like NY are mostly underwater for the global warming meltdown, and technology is frozen at the beginning of the XXI century. So they have a NERVA-derived vapor core NTR projected by Dougan and Diaz (https://www.google.com/url?sa=t&rct=j&q … LYs2231OZ0) but not a functional gas-core. DD's vapor-core has a T/W ratio of 5, good for an orbit-to-orbit spaceship but too low for taking-off from ground, where chemical rocket are still used. The tech is frozen so they still use RS-25 derived LOX-LH2 rocket busters.
Have you some link of 9000 s gas-core?
I posted images of one individual's rendering of what he thinks the inside of Starship will look like. That's based on computer graphics SpaceX released of the outside, on actual images of real Starship prototypes from the outside, and verbal description Elon Musk gave of what will be inside. Rather than repost, I'll post a link
http://newmars.com/forums/viewtopic.php … 70#p172070Reasons Elon is looking at LCH4 for Mars:
higher specific impulse
almost same storage temperature as LOX. By storing LCH4 just a 21°C colder than it's boiling temperature than O2, they can be the same temperature.
liquid storage temperature at pressure is below ambient temperature of space, so a sunshade is enough to keep it liquid
can be made on Mars
I don't know Starship cryogenic pressure, but Shuttle's external tank reached 38 psi (260 kPa) for LH2, 25 psi (170 kPa) for LOX. Normal pressure when sitting on the launch pad for LOX was 20 to 22 psig, but could achieve 25 psi during launch.
LOX boils at -182.96°C @ 1 atmosphere pressure, freezes -218.78°C. RP-1 freezes at -73°C, boils +147°C. So with RP-1 you need more than a thin metal bulkhead.
SpaceX Starship is perfect for Mars where the CO2 atmosphere can be used to synthesize CH4 via Sabatier reaction and Mars low gravity consents to reach orbit and depart in one stage. The planet target of my novel is not Mars but a superearth (via a wormhole orbiting between Earth and Venus): the exoplanet has a breathable atmosphere of 1.3 bar and a surface gravity of 1.3 G so a SSTO is impossible with current technology and the habi-lander is a one-way ship that is converted in a ground habitat after landing. The colonists remain on the planet, while the crew reach the mother-ship with a two-stage ascender, with LOX-LH2 rockets. Return propellant is made via electrolysis from water: I think LOX-LH2 is the easiest propellant to make in a earth-like planet with a nitrogen and oxygen atmosphere.
Yea, the tank would have to be pressurized to hold the weight of regolith on top. Starship was assembled and welded outdoors, so could be dismantled and reassembled outdoors on Mars as well. Here's serial# 1 from February 2020. Note a single header tank in the nose instead of separate LOX & LCH4 header tanks in the main LCH4 tank.
https://i.redd.it/d4j68aljuch41.png
A close-up of assembly. Don't know which SN this is. It puts size in perspective.
https://techcrunch.com/wp-content/uploa … cex-2.jpeg
And a render of SN6. This shows one header tank in bulkhead between LOX & LCH4, the other header tank in nose. Yes, it's rendered on its side but lands vertical on its tail.
https://pbs.twimg.com/media/EgCRXWFXkAEWsli.jpg:large
My spaceship is a "habi-lander": a 60 meters long 10 meters diam, stainless steel spaceship that is carried by a vapor-core modular nuclear spaceship (like GW's design http://exrocketman.blogspot.com/2012/07 … icial.html ), then she detaches herself from the mother spaceship and lands on the planet whit 48 colonists, who live inside it during the trip, while the nuclear spaceship parks herself in orbit, waiting for the launch window, then she departs with a little habitat for a crew of 6. The habi-lander has a dry mass of 326 tons and carries 164 tons of landing propellant: I chose LOX-RP1 because RP1 is not cryogenic and can be used as a screening mass for solar flares. The landing rockets are 24 SpaceX Merlin mounted at the sides of the fuselage for belly landing.
Hi to all,
Here in Italy I was summoned again for the second wave, put in stand-by and never called. So I continue writing my SF novel.
I have a SpaceX like starship, and I thought to put the storm-cellar inside the landing propellant tank: with 164 tons of LOX-RP1 3.36 O/F ratio I have 48.8 tons of RP-1, so I can have a sphere of 8.4 m of diameter with 20 g/cm2 of RP-1 as a storm cellar for the crew, sparing a lot of mass. I would like to ask to the experts of this forum if it might be a good solution and if it is possible to do the same with cryogenic propellants like L-CH4.
Thanks to all.
Hi to all,
I've finished my quarantine and on 13 may I went out for the first time. Just a walk around my home with my dog, but it was wonderful to see the sky again.
A week later, the lockdown has been eased, and many people happily walk together in the parks of Rome, like the pandemic had never happened. I strongly hope to be wrong, but I fear a second wave.
Thanks for your support,
Now I'm still in quarantine in my home in Rome and I'm in good physical shape, showing no symptoms. I will be released on may 12 at midnight, which means I will be allowed to take a walk with my dog in the parks near my home.
Here in Italy the lockdown was partially eased but the epidemic still kills almost 370 people/day, mostly in the north. The middle Italy and the south Italy were partially spared by the virus, but it only happened because the lockdown was instated before the arriving of the viral wave. I strongly fear that a second wave may come if the lockdown is ended too early.
I hope that you and your family are fine. How is the situation in your cities?
For Quaoar re #102
It is ** good ** to see your safe return from your national service! At the same time, it is daunting to think about what your experience must have been like.
In the US, a number of media outlets have taken great care to share the experiences of medical workers in real time, and in video biographies recorded after a shift ends. From these it is possible to imagine what the situation must have been like for you and your co-workers.
While you were away, there have been some changes. SpaceNut appears to be in good health but unable to access the forum due to issues with the Internet connection. kbd512 has accepted the (to me awesome) responsibility of trying to fill SpaceNut's shoes.
Various discussion topics have come up that might lend themselves to a Science Fiction treatment.
Best wishes for continued good health for yourself and your family, and all those you worked with and recovery for those you assisted in Liguria.
(th)
Thanks
That's my story: We were gathered on April 8 in a hotel near Rome main train station, where we had a briefing with the chief of Italian Civil Protection Agency. The next day we took a military bus which brought us in the Italian Air Force base of Pratica di Mare (near Rome) where we took a military plane for Milan. In Milan airport of Linate we were split in groups and sent to the affected regions of northern Italy via buses.
I was assigned to Liguria and sent to Sanremo with another doctor. They gave us the protection devices (gore-tex jumpsuits with hood, glasses, face screens, gloves and plastic bags to cover the shoes) and a car, then ordered us to take care of some highly infected nursing homes in the district of Imperia. We firstly went in a nursing home in a little village in the mountains (Liguria is an arc of coast mountains in the northwest Italy). There were so many death that the staff was forced to hoard them in the chapel, wrapped in bleach sheets. During the three weeks of our turn, while taking care of the survivors, we managed to convert nursing homes in infectious disease ward, with a clean zone, an infected zone and a safe path for dressing and undressing, we imposed the use of the protection devices and trained the nurses and the operators to correctly wear them, to not get infected and spread the disease.
We worked together with highly experienced military nurses of Italian Army and Italian Navy who taught us a lot of very useful tricks to not get infected while undressing, like spraying bleach over the jumpsuits and the face screens before removing them.
The day before leaving, we were tested for covid19 and found negative. But we were put in quarantine the same, so I have to stay locked at home until May 12 at midnight.
Quaoar,
Take care of yourself. I hope to read more of your posts in the future.
I survived and today I come back home after a 21 days turn of service in Liguria (north west coast of Italy), but I had saw more death in these days than in all my precedent career.
Thank to all for your support.
Quaoar:
Watch out using zirconia. It tends to crumble within a few reuses, especially if you take it up as hot as it can go, which is considerable. I got that warning from a zirconia maker.
The fancy modern materials Kbd512 may know more about. I'm too old and obsolete for that. But fiber-reinforced ablatives is a good way to go. carbon and silicon carbide fiber look promising to me, if the right matrix can be identified. Looks to me like there might be a large number of promising candidates these days.
GW
Thanks, GW.
Following your advice, I'll use surface protected ablator (SPA) a carbophenolic ablator wrapped inside a C/SiC leading edge with ventilation holes. I have found it can withstand a heat flux up to 3.8 MW/m2 so it looks to be OK for the leading edges of my waverider, according to your formulas.
I also would like to use SPA for the other TPS tiles: It's a good idea or it's better to use PICA-X?
P.S.
My call has arrived. On Wednesday I'm going to be deployed on the battlefield.
I thank all of you, my friends, for the help you gave me during these years to write realistic hard-SF novels, and I hope I will continue to post on this forum.
If you don't see my new posts any more pray for me.
I hope you and your families will be safe, and we all will see the light at the end of this tunnel.
Best wishes for all of you
Quaoar
