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Quaoar:
I put some entry heat protection estimating techniques up on "exrocketman".
GW
Thanks GW,
After reading you lesson, I was able to calculate the heating rate of the leading edges of my waverider: R = 12.5 cm, v = 18.9 km/s, air density at 90 km = 0.000019 kg/m3 (It's an extra-solar super-earth).
It results 1456.6 W/cm2 of convective heating and 9834 W/cm2 of radiative heating, with a total heat rate of 11290.6 W/cm2, too much for PICA-X, for which I found an upper limit of 1000 W/cm.
So I made some research and discovered Surface Protected Ablators (SPA): an ablative material like phenolic carbon wrapped inside a hot hard material like C/SiC with ventilation holes. The C/SiC conserves its profile, withstands the air load and is cooled by the ablator. It was used on German capsule MIRKA and it can withstand up to 13000 W/cm2.
http://isa-space.eu/5th%20TPS-WS%20-%20 … 0final.pdf
Other promising materials are:
1) low density porous ceramics (foamed zirconia has the best performances) impregnated with ablative resins*, which conserve theirs profile while the resins evaporate cooling the ceramics.
https://books.google.it/books?id=xekfi1 … s+ceramic+
https://patentimages.storage.googleapis … 395035.pdf
2) The Sepcore concept: a sandwich with an ablative outer layer, a hot C/SiC core and an inner layer of insulating low density material.
http://www.esa.int/esapub/bulletin/bullet94/ROUM.pdf
*Porous ceramic coolers are very ancient devices, probably invented by the Egyptian to drink fresh beer in 3000 B.C.. They mixed clay whit salt and made jars. When they put water inside the jars, the salt dissolved in the water leaving a porous ceramic. They put beer in sealed amphorae, put amphorae inside porous jars and filled the jars with water. The water exuded over the outer surface and evaporated cooling the water inside and the beer.
Porous ceramic jars were still used in Italy in the sixties, when many country villages were not yet electrified. I remember my maternal grandpa used one of them in his vacation house in the mountains of Sila, to keep fresh his white wine.
It might be interesting to note how old ideas are recycled for new hi-techs
Quaoar,
I think there's a fundamental misunderstanding of how this works. You're clamping the pylon to a welded attachment point on the exterior of the propellant tank. You don't need to penetrate the exterior heat shield to do that. There's going to be a small air gap between the back of the tile that the pylon is connected to and the exterior of the propellant tank- if nothing else, so that the tank and tiles can expand and contract. The entire back face of the tile isn't jammed up against the propellant tank and held in place with some comparatively weak adhesive. Instead, we're using a short little standoff in the form of the pylon and locking clamp. That's the space you have to work with. You can use tools to rotate the locking collar into place or tension the clamp, whichever system you choose to use.
But even if there is a small air gap between the tiles and the steel skin - which is very useful and can also act as a Whipple shield against meteoroids - the tiles form a continuous surface over the shell. So when you insert the last tile of the mosaic, you have no more gaps to insert a tool and lock the last clamp. That's why I thought to some sort of snap fastener.
Quaoar,
That's the idea, more or less. I was actually thinking of a sort of clamp that has just enough "spring" to it to enable thermal expansion and contraction. In other words, the clamp allows the pylon (that the rest of the tile is attached to) to move up and down as the tank expands and contracts. It's like the expansion joints on stainless steel exhaust headers, but swaged onto the tile's pylon and tempered to provide the correct amount of "spring" after it's affixed to the pylon. The pylon itself will have a "lip" on the end to keep the expansion joint from sliding off of it. The expansion joint is then rotated to clamp or un-clamp it to the tank, a bit like the blunt "threads" on a lightbulb, but also including a detent to lock it into place. This can all be done with a short section of tubular sheet steel.
It's way simpler in practice than it is to explain what it's doing. Once you see one of these devices, which have been in use in aviation for many decades, you'll laugh at how simple it is. It does require forming dies to progressively swage the steel tube over the pylon lip, but that's the extent of the special tooling required. Like I said, it's been in use for decades and it's a commercial product that's pretty cheap. I think they cost a dollar or so and we might need several thousand of them per Starship.
Alternatively, there are step-less screw clamps or hose clamps or collared slotted spring-loaded studs (used for fastening engine cowlings) that could serve the same purpose. In fact there are at least a half dozen different kinds of fasteners that would do what I had in mind. Those are more expensive, but you could just walk into the hardware store with your credit card and walk away with high quality stainless steel tensioning fasteners that does what we need it to do.
The problem is that you don't have access to the space between the shell and inner face of the tiles, because the tiles and the shell cannot be pierced. So you need some sort of snap fastener which doesn't need to be screwed, bolted, riveted or rotated but only locked by pressing the tile over it, as when you glue the tiles of a parquet.
Quaoar:
I put some entry heat protection estimating techniques up on "exrocketman".
GW
Thanks GW
I'm one of your followers
GW,
I see you touched on why I suggested clamping to provide strain relief to the tiles. If anyone else is unfamiliar with what I'm talking about, it's the ability of the propellant tank to flex during the various heating and cooling cycles associated with ascent and on-orbit operations and reentry without cracking any of the tiles surrounding the tank. Stainless will flex quite a bit in comparison to the heat shield tiles. Also, the fiber-reinforced ceramics are not as brittle as the traditional tiles. Since those are attached to X-37 using bolts, I presume they can be attached to Starship using bolts. TUFROC is not a homogenous material / structure in actual implementations. It's a sandwich of different materials with different properties. The cap is a type of glass to prevent oxidation during reentry, followed by a toughened ceramic that absorbs and re-radiates the high thermal load, followed by a much tougher substrate that's used as the attachment point for the heat protected structure.
For those who are having a tough time visualizing how this would work, picture the large blunt foam tipped paint brushes with wooden handles sold at the hobby stores. Imagine that the foam is actually the high temperature fiber toughened ceramic tile. Imagine that the wooden handle serves as a stubby attachment point. The handle is just one of the non-homogenous portions of TUFROC (the other being the glass cap over the ceramic tile for oxidation protection) and is much tougher (greater tensile strength than the ceramic tile and greater ability to deal with shear loadings) attachment point / insulation that inhibits heat transfer between the hot ceramic tile and the protected structure (the propellant tanks of Starship, in this case). Now instead of a bolt drilled into the stubby "handle" of the tile / paint brush to attach it to the propellant tank, we develop a properly tensioned stainless steel ring that clamps around the entire circumference of the "handle" to permit the propellant tank it's attached to to expand / contract without fracturing the ceramic portion of the tile assembly. Bear in mind that we're talking about fractions of an inch, for any given tile, when we're talking about the tanks flexing under thermal load. In the NASA tech briefs, this is known as the "pylon" attachment system. We could have a single pylon per tile or a number of pylons, perhaps three of them, and much larger tiles.
I can even imagine a BNNT cable-pull system that locks / unlocks individual tiles so that you can stand under the tail of Starship and unlock tiles all the way at the top of the vehicle with the help of another crew member who will catch and remove the tile that requires replacement. The cable would be attached to a tensioning ring and threaded through pulleys that provide leverage. The edges of the tiles could be supported by additional steel springs that prevent the edges of the tiles from deflecting too much under thermal and mechanical loads.
Please, let me know if I correctly visualized the pylon concept: every tile has one or more pylons with a groove on the base which is forced into a steel ring welded on the steel shell almost like a snap fastener. Does it work this way?
Can TUFROC tiles or leading edges withstand a 19 km/s atmospheric entry?
Kbd512 knows more about the newer materials than I do. I've been out of it for a long time now. What I know is the older stuff, up to shuttle's low-density tiles and carbon-carbon leading edges and nosetip. That would be the old reinforced phenolics, Avcoat as flown on Apollo, and what I have learned since about PICA and PICA-X.
For adhesive work, there are no epoxies with adhesion capability past 290 F, and there are no silicones not charred loose at 600 F. There are ceramic adhesives that go hotter, but they are for metal-ceramic bonds.
NASA has a real "not-invented-here" problem with holes in heat shields. They gave a used flight test Gemini to USAF for USAF's MOL program. USAF sawed a circular hatch hole in that used heat shield to test for its Gemini-B design, and then flew it (unmanned) for the one-and-only flight test that MOL got done before cancellation in 1969. It worked fine coming back from orbit. As a reflown, used heat shield, with a big hatch cut in it. The damned thing is still on public display today.
GW
Hi, GW
I have found this new 3M 1137 sealant: they claim it works up to 2000 F
https://www.3m.com/3M/en_US/company-us/ … 008&rt=rud
For the steel outer skin of my waverider: should it be a bulk plate or can it be a honeycomb or a steel foam sandwich?
Quaoar,
I would think nuts and bolts or studs would be used. It'll most likely be some kind of torque-to-yield design. So long as the loads applied don't exceed the clamping force, that should prevent fatigue failures. Achieving the correct preload when torquing the bolts is critical, though, which means training people to use a torque wrench. Millions of mechanics have figured this out, but once mechanics with PhD's are thrown into the mix all bets are off. The upside is that the mass associated with the fastening hardware should be minimized. The downside is that you have to throw that fastening hardware away whenever you need to replace a tile.
Edit:
Here's a good paper on why the Space Shuttle engineers selected the various materials that they used and some of the testing methods used to retire risk associated with the fatigue life of the orbiter's airframe:The structural engineers who designed the orbiter's airframe had direct access to the designers of the Concorde and SR-71, so they took the design elements from those two high speed aircraft that would work for the Space Shuttle program and blended them with various other techniques required to address the unique challenges of the extreme thermal flux produced during reentry. I had books on this stuff as a kid.
How to deal with the holes for the nuts in the tiles? By gluing over some kind of PICA-X corks?
Just another thing, please, the steel skin is a bulk plate or a honeycomb?
Another possibility is the steel foam sandwich: what do you think about it?
Direct bond means that it will transfer to the shell but with layers of adhesive and blanket you isolate and slow that process of thermal conduction through them...
Tiles are glued to blankets which are glued to the steel shell with a UHT silicon adhesive. It seems to me a good solution.
Thanks I've found this UHT adhesive of 3M which resist up to 2000 F or 1366 K
https://www.3m.com/3M/en_US/company-us/ … 008&rt=rud
it might be OK to fix PICA-X tiles on a stainless steel shell
Quaoar,
Hmm...
Aluminum does okay with LH2, but stainless fares even better and steel sheet is some of the cheapest stuff you can buy and robotic welding is much faster and therefore cheaper than machining Aluminum plates with giant milling machines and then bending the "Aluminum potato chips" into propellant tank gores, anodizing them to prevent stress corrosion cracking, and then friction stir welding them (which can also be done with thicker gores of stainless). The Centaur upper stage is a non-standard thickness super-thin stainless balloon design that's custom rolled to be thinner and then planed after welding to be thinner still. All that extra work and cost only achieved a 5% decrease in structural mass fraction, but as Tory Bruno said, "it's the Ferrari of upper stages". This transport vehicle will be large enough that standard thickness sheet can be affixed onto jigs / tools and robotically welded with a friction stir welding machine.
If the vehicle had to fly under power at low speeds, then Aluminum is lighter for a given level of strength and therefore more cost effective to operate, which is also the entire reason why Airbus and Boeing switched to CFRP / GFRP- because it's even lighter for a given strength than Aluminum, but again only when temperature limitations are respected. Steel is by far the easiest material to work with and so long as its been properly designed and fabricated it'll provide years of dependable service.
I think you'll still be forced to pay the piper, in terms of structural mass, if you try to make the structure lighter by using a lighter but less heat resistant airframe, in terms of TPS mass to insulate the airframe. Skip the adhesive and go straight to mechanical fasteners. Those work well and the results are highly repeatable. Between maximum practical durability and maximum feasible payload performance, I'd choose maximum practical durability for a reusable spaceship every single time. Propellant is cheap compared to a dead crew and destroyed vehicle. SpaceX has the right idea, I just think it needs a lot of refinement and they're doing that.
Thanks.
Which kind of mechanical fastners? The tiles can be bolted, but in this case the holes for the nuts has to be covered with a PICA-X cork, this time glued. Do you know some kind of blind snap fastners?
Just another question: The lander is a single use 30 meters long biconical vehicle which detaches from the waverider before the arrive, makes a direct entry at 18 km/s in a super-earth atmosphere (surface gravity 1.3 g) then lands with four cluster of seven Apollo type parachute and airbags.
Being a one-way vehicle the lander can be done in aluminium or is better in steel?
Quaoar,
Alright, I'll bite.
How do you think we should go about teaching young people to make reasonably good context-driven decisions?
I try to teach my own kids to consider the entire context of their decisions when making decisions and that they have to be willing to live with the consequences, too.
Prime Example:
My daughter's teacher taught the kids in her class that they should just take whatever assault some other kid dishes out and not fight back at all because her parents could still be sued by the parents of the kid who initiated the assault / fight. I told her that if someone assaults her at school, especially if they use any kind of weapon against her, then she has my blessing to fight back if she thinks that's her best option, or not if she thinks fight back is not the best option. I also told her that if someone just smacks her and then runs away, that doesn't give her an excuse to go chasing after that person and doing to them what he or she did to her. There's a world of difference between someone trying to pound your head into the pavement like a tent stake and someone slapping you and running away or merely saying something to you that you don't like.In any situation where she can get her teachers, or the school's principal, or the campus Police, or her father to address the issue, she should do so. If someone backs her into a corner and tries to club her to death, then I think she should fight back as best she can. I think standing there and allowing someone to beat you to death is pure idiocy, but apparently that's just me. Science says people who fight back generally live longer than people who don't, but liberals only believe in science until it conflicts with their emotions or ideology. Anyway, that's just "uncommon sense" in my book. There's no single answer to every conceivable problem, especially when lives are at stake. As I told her in closing, "Welcome to the not-so-black-and-white real world. Think through what you intend to do very carefully before you arrive at a situation where you only have a split second to act."
That's the idiocy of politically correctness. People seems unable to understand the context in which we are. Our ancestors used to said that every rules have to be applied "cum granu salis" that can be translated "with a grain of salt".
Quaoar,
Those Aluminum-based CMMC's I messed with were a good example of an Aluminum alloy that retains substantially more strength at higher service temperatures, but good luck finding someone who wants to machine it. It's also as expensive, by weight, as a mid-grade stainless. I was only thinking of using welded stainless to permit much higher service temperatures as part of a complete thermal soak design. The stainless is definitely going to be stronger than Aluminum on a per-unit-mass basis at 600F+, but really it's the issue of having cryogenic propellants on one side and blow torch temperatures on the other that seemed like a significant thermal expansion and subsequent metal fatigue challenge if we stick with using Aluminum.
I presume this hypersonic wave rider vehicle will contain cryogenic propellants, right, or will it be an empty beer can when it lands?
Yes I use LOX-LH2 with four 2.7 MN P&W Cobra (derived from SSME), but it never land and fly orbit-to-orbit using aerocapture at both ends plus an aero-gravity assist in the return flight to spare propellant. Probably a steel shell is even more resistant to fatigue. Do you think it's better to use steel even if the outer skin temperature is constrained by the silicon adhesive?
It's possible to fasten or brazing the tiles instead of gluing them?
Terraformer,
Your government's list of new rules just described my daily life before all of this happened.
I rather enjoy the lack of throngs of people, but it's also bad for the economy.
Do you find it at all humorous that any government needs to create laws to prevent people from congregating together in large groups when there's a lethal new airborne pathogen we can't contain? Does that not say something about the baseline stupidity of people?
I've always wanted to remove all the warning labels and laws against baseline stupid behavior, just to see what would happen. After watching what our college kids were doing over Spring Break before our governors put an end to that, I think I already know what the outcome would be and that takes all the fun out of the experiment. If we need to tell our college kids that they need to refrain from getting drunk or stoned out of their minds, en masse, for a few weeks or months so that they don't spread disease to the people paying for their party, what does that say about our future?
We need to give everyone free college education, or so Bernie Sanders says... So, you know, they can then go out to a public beach on Spring Break and spread disease during a global pandemic, proving their moral and intellectual superiority to the rest of us once again.
What good is a college education if the people who come out of the program are still morons? Do tax payers really need to pay for that?
Colleges don't teach you how to become intelligent. A moron who goes to college will become an educated moron not a smart person.
Quaoar,
If you actually allow Aluminum to reach 620K / 656F / 347C, then it's likely to be a problem for structural reasons. Aluminum only starts to melt at 1,200F, but it rapidly loses strength before you get it that hot. At 600F about half its strength is gone, so you're either going to make the airframe pretty stout or the airframe won't survive. 656F is nearing the annealing temperature range for certain types of alloys. I think 6061-T6 is annealed at 775F, but can't recall off the top of my head. That said, the non-reusable Apollo capsule was designed for a maximum allowable service temperature of 600F during reentry, prior to main chute deployment, at the bond line between the heat shield and the capsule, so maybe this would work if some kind of sacrificial Aluminum honeycomb and ablative heat shield are replaced or maybe you could thermally soak the entire airframe (windward and leeward side) using heat pipes to slow the temperature rise. The Space Shuttle's primarily Aluminum airframe was limited to 350F, which was an acceptable limit over its design service life criteria.
I found this paper about a high temperature aluminium alloy named NASA-389
https://ntts-prod.s3.amazonaws.com/t2p/ … TOPS-6.pdf
At 588 K or 600 F it conserve almost 60% of its strength, but even the adhesive at this point is very near to failure, so the substrate has to be kept at lower temperature (below 400 F or 477 K). That's why I see no reason to use steel, which is heavier, unless you do use some other kind of temperature resistant fixing method.
P.S:
We Europeans are very unfamiliar with Fahrenheit scale so we have to use online converters to realize what we are talking about. Many years ago in US, I carbonized the tomato sauce over a pizza before cooking the dough for setting the oven at 200 F, like an Italian oven which has to be set at 200 C to correctly cook a pizza.
Thanks to all,
Having entry speeds of about 19-17 km/s, I think to use PICA-X ablative TPS on an aluminium honeycomb skin, for my waverider, and to change the PICA-X tiles every new mission (I don't know if TUFROC or CMC can withstand entry speeds of such order).
I chose an aluminium substrate instead of a steel one, because the weak link of the chain is the glue to fix the PICA-X tiles on the shell: the best silicon adhesive I've found has a maximum temperature of about 620 °K, that is less than the maximum temperature of the best high-temperature aluminium alloys, like NASA-398, which is about 640 °K.
Steel might worth the weight penalty only if using some kind of high-temperature resistant adhesive method like brazing, but I don't know if PICA-X tiles might be brazed on a steel surface.
Are my thoughts right?
Quaoar,
Roughly speaking, normal human visual acuity correlates with 1 arc minute, so anything more than about 300dpi is beyond your ability to distinguish what you're seeing on a display. Using modern digital imaging technology, cameras are the most practical way to protect the structural integrity of a hypersonic vehicle and also provide a stunning view of the outside world. Such vehicles are flown primarily with very accurate instruments and computers with high degrees of redundancy to preclude single points of failure compromising the ability to pilot the vehicle. The latest and greatest high-DPI displays are completely indistinguishable from what your could eyes pick up at normal viewing distances. There's no reason the entire cockpit couldn't be a gigantic continuous display that feeds hyper-accurate multi-spectral data to the crew for their viewing pleasure.
So I've eliminated the windows. Given the waverider uses PICA-X thermal protection, which is also good as heat sink, the shell can be build in carbon composite or aluminium or it has to be build in steel or carbon-carbon?
Which kind of adhesive is used to fix the PICA-X to the shell?
Quaoar,
I hope your civil service goes well. I know perspective is a difficult thing to maintain in difficult times, but I think most of us are going to get through this. In the end, we're all going to the same place and no matter what we choose to believe there is no escaping that fate. Before you arrive at that place, do whatever you feel you must with the time you do have. When I arrive at the end of my life, I want to know that I made good use of the time I had and that I did what I felt needed to be done. As long as I do that, I can accept the final result.
Thanks,
I'm still waiting for the call. I will be probably deployed in Lombardy.
I fear my enemy, but I want to give my little help to win this war.
13th day of "house arrest".
Every day is the same. I know it's Saturday 21 only because it's written on my computer.
I go out to buy some fruit. There is a long line in front of the grocery store, so I walk 200 meters to another grocery, which is deserted. The scaffolds are still plenty of fruit. I buy some bananas, oranges, apples and onions and quickly go back home. I make some gym in my room, then I write the 4th capitol of my new SF novel, about a chase with flying boats on a super-earth tidal-locked to a red dwarf. Then I eat two eggs and some fruits, I give some kibble to Mr. Spock (my cat) and restart writing.
In the meantime it is now evening. I open google news: today we lost 793 people (546 in Lombardy) and the total death toll has rose to 4832. Many doctors have been infected and are out of fight. In northern Italy hospitals have ran out of doctors.
I read an advice of Italian Civil Protection Agency looking for volunteers.
I'm a SF writer, but I'm still a medical doctor with three decades of experience. I have a briefing with my son and my daughter, who grant me the permission, then I fill the form and enroll myself.
In the next few days I might be deployed on the battlefield, but I hope I will continue to post in this forum.
Quaoar,
I would use AlON windows with RCC gap panels and metallic gaskets. The AlON plates would be mechanically sealed to the pressure vessel using the metallic gaskets and the gap panels would prevent gases from directly impinging on the seals / edges of the windows where they're affixed to the pressure vessel. Oxygen would still attack the RCC, but the idea is to have a very high-precision sub assembly that prevents the oncoming flow from directly striking the attachment points for the windows- in other words the exterior of the entire windscreen surface and interface with the rest of the pressure vessel are as smooth as a plate of metal.
In the Space Shuttle they had protrusions from the attachment points associated with the tiles surrounding the windows, which is what I'm trying to avoid to preclude creating local hot spots. It worked because the windows were on the leeward side, they entered with a high angle of attack, and thus the air pressure was something like 1/100th what the windward side experienced. Leading edges aside, if this is supposed to be a thermal soak design then we can't have drastically different localized surface temperature variations caused by aerodynamic heating effects associated with all those protrusions from the skin of the vehicle.
Given current technology, windows for hypersonic vehicles are mostly a psychological thing for humans, which is the only good reason I can think of as to why we still have them. If I was designing a hypersonic vehicle and had freedom of design decisions then my first priority would be protecting the vehicle's occupants and that means no windows, so there wouldn't be any. We'd have hundreds or maybe even thousands of tiny cameras with Sapphire lenses to provide a composite view of the outside world on displays, similar to what we did with the DAS (Distributed Aperture System- a series of multi-spectral cameras to provide 360 coverage of the outside world) on the F-35.
Ultimately, I would like to have a reentry vehicle that doesn't need to reenter in a very precise way in order to survive the ordeal.
Thanks, nice idea.
So, no windows, but external cameras and monitors. Cameras have to be placed only in the leeward side or even in the windward one?
P.S.
As a retired medical doctor, today I volunteered in a medical task force of Italian Civil Protection Agency, so in the next few days I might be enrolled and deployed on the battlefield. I hope to see the light ad the end of this tunnel.
The Italian figures are v. puzzling. Even more so when you consider that the vast majority are from one region of Italy.
In terms of population (deaths per million) the death rate in Italy is over 90 (!) times that of the USA - which also has a large elderly population and lots of people with diabetes and other underlying health conditions - and of course loads of personal contact with China...
So I am yet to find anyone in the mainstream media come up with a satisfactory explanation. I am sure the phenomenon of young and old living in the same household is part of it, as is the close physical contact of greetings - but that's true of Greece, Spain, parts of France and other parts of Europe.
In Lombardy only severe case are tested for covid19, resulting an higher mortality than Veneto where the population is carpet tested.
In these days it was found that the contagion maps exactly match the concentration of the factories. Lombardy and Veneto are the most industrialized regions of Italy, so they have more and more cases than other less industrialized regions.
This points out that Italian strategy of "partial lock-down" (people at home, schools, stores and public office closed, but factories still working) doesn't work.
But our government has not the gut to shut down factories which doesn't produce essential items, so we are still producing something like F35s, which sincerely are not the best effective weapons for detecting, targeting and destroying a small enemy like a virus.
The media is targeting joggers, as scapegoats of this failing strategy, and now soldiers in combat suit patrol the streets of many cities to fine running people of 206 Euro, which probably will be never collected. But, as the crematory ovens works at full blast, workers still wake up at five o'clock, spend hours in very crowded buses to reach the factories, where they work side by side, while lawyers, magistrates and scholars are still eruditely discussing whether take their temperature is a violation of privacy or not.
Quaoar,
AlON melts at 2,150C and also provides fairly impressive ballistic protection, with a hardness pretty close to that of Sapphire. Quartz melts somewhere between 1,600C and 1,700C. AlON's bulk density is about 1g/cm^3 greater than quartz, but there are advantages that come with that extra mass. It's about 9 times as thermally conductive as quartz and CTE is slightly higher, but maybe that's a good thing if this new stainless vehicle is going to use thermal soak and eschew the use of ablatives.
Thanks for the tip.
A double layer of aluminium oxynitride might be also more effective against micro-meteoroid impacts.
I imagined a waverider with a shell in 3D carbon-carbon composite with white PICA-X thermal protection. For the windows I can use a AlON double layer with a reflective sliding shield in the middle.
How to fix PICA-X to the shell?
I read that brazing is better than gluing.
The pandemic has broken out even in Spain, with the epicenter in Madrid.
Today I have red they lost more than a thousand people.
It seems to me to see again the same movie. They are almost ten days behind us.
Indeed - but that seems to be what they are doing in the temporary hospitals...putting people with respiratory diseases very close together...how is that not going to increase the death rate or the rate of worsening symptoms as people become infected with each other's viruses?
That's the emergency. The ones who end up in field hospitals are those who would die anyway if not vented.
Sure, a regular and clean hospital is far better, but when people get sick in thousands healthcare systems go haywire.
You can see how this works...in normal circumstances (before the Coronavirus scare) an aged person with a respiratory problem goes to see the GP (local doctor) and is then given antibiotics and told to go home...concerned family look after old person as much as possible. The person either gets better or dies. But now - aged person has to contact telephone line. Symptoms are confirmed as possible Coronavirus. Because of the person's age, it is determined they need to be seen my medical staff and tested. Medical staff are always going to play safe in these circumstances and so patient is immediately hospitalised...in hospital they are plunged into a frightening and demoralising environment of antiseptic decor and unidentifiable medics in masks. Their immunity is reduced, now isolated from their loving family in this horrible environment, and - very possibly - they are infected with other viruses ciruclating in the hospital...and so they die.
We need to get over our childish ideas of "hospital = good = get better". We need to think "hospital = concentration of risk = avoid if possible".
In fact, it's better to test suspected cases at their home.
Here in Italy there are just some people who pretend to be medical personal in charge of test and goes door-to-door to old people to rob them. I think those jackals should face the firing squad.
The shuttles came back without any shielding for the large windows but if you do not need to see through them during landing then draw a metal shield on the inside of them should do the trick. No need to get fancy able it just latch that swing over the panel after you push it up to the sealing surface.
Thanks, nice idea.
Space shuttle enter from LEO at 8 km/s. My novel is set in a red dwarf system with many planets, almost like Trappist-1. Simulations give me enter velocity from transfer orbit of about 18 km/s, so plasma radiative heating is more severe.
For my waverider, I thought to use quartz double layer windows with a sliding reflective metallic shield in the middle.
Even the upper surface has to be protected, so I thought to low-density white TPS tiles like those of the upper surface of the space shuttles, It's a right choice?
The story keeps changing. I have read lots of times that China ignored the coronavirus outbreak for about a month, certainly there was no lockdown during that period. Coronavirus is clearly highly infectious. Are we really supposed to believe that the subsequent lockdown was super-effective. Excuse my scepticism...
"Test, test, test" as recommended by WHO is a very effective way of crowding old people into hospital facilities where they can catch other viruses and die.
One guy blamed for the Lombardy outbreak! lol We know there were tens of thousands of people coming from China to Europe in the first weeks of this year and hundreds of them would be infected, and many of those would be effectively asymptomatic.
Mattia was patien one. We don't know who infected him: may be a Chinese tourist or an Italian coming back from China. Who knows?
But put an infected man in a very crowded room with hundred of sick and debilitated people for 36 hour and figure out what mess can happen.
Hi Quaoar:
To answer your question, I would think covering a window to stop radiation from the plasma heating up things inside would be beneficial, although it might not be required. Depends upon the vulnerability of what get irradiated
The crew.
We here in the US are having panic-buying difficulties, because people have been lied to by their favorite internet and social media sources. The business model is getting paid by more clicks, without regard to the truth of what is posted. That's why so much bogus BS is out there. I posted an article debunking this crap on "exrocketman" today.
I hope you get through the troubles in Italy soon. We here are entering a sort of lockdown that is not really a shelter-in-place lockdown. But essentially the restaurants, theaters, bars, schools, and sporting events have been shut down in Texas, and across most of the US.
This will go on for a few to several weeks until the infection rate peaks and drops. Then we have to deal with the economic recession that is the inherent fallout from this. This is not a lot different from the 1918 flu pandemic, and it is nowhere near as bad as the 14th century Black Death pandemic. We'll get through this. All of us. Everywhere.
GW
Hi, GW,
I hope you are well.
I have red your blog: what you say is correct.
Why not for you to join us on this topic:
http://newmars.com/forums/viewtopic.php?id=9317&p=6
We share our experiences in dealing with this pandemic, and your contribution is precious.