New Mars Forums

tahanson43206,

That's the power turbine for the 300MWe power plant.  Every American aircraft carrier since the Forrestal class was built, whether using oil-fired boilers or nuclear boilers, has been equipped with 4 geared steam turbines that deliver 208MW of total power output.  That SCO2 turbine has 600MWth of CO2 flowing through it, yet it's dramatically smaller than just one of the geared steam turbines generating 52MW.  It's so small that the entire power plant could be incorporated into the prop hub, meaning entirely external to the skin of the ship.  Those human hands on the blocks of steel supporting it aptly illustrate how much wildly smaller it is than any steam or conventional gas turbine.  It's that small, yet delivers more output than all 4 screws of a super carrier.  In point of fact, that 300MW turbine and the turbine casing would easily fit inside the prop shafts of our exiting aircraft carriers.

I get that it's hard for most people to wrap their heads around.  Nothing else in the world except a rocket engine turbo pump has that kind of power density, but these power plants are designed to continuously produce that much power for about 100,000 hours (11.4 years).  SCO2 turbines, 10:1 compression per stage supersonic inlet jet engines, and adaptive cycle conventional gas turbines are the future of gas turbine engine technology.

Here are a couple of alternative habitat shapes we could also try, rather than a simple torus:

Apparently this one cannot be linked to:

The advantage would be incorporation of a smaller, albeit still fairly large common area for the colonists to gather in.

GW,

If the data doesn't match your beliefs about it, then the data is wrong.  Classic.  Alright, then, live in your unreality.

No drop in military aid to Kyiv since US policy shift, NATO official says

Here General Keller is saying it live:
DWS News -  NATO Supplies 220,000 Tons of Weapons to Ukraine in 2025, Major Gen Keller Confirms | AH1N

Major General Maik Keller, NSATU Deputy Commander

Maik Keller

The American government is lying, all the defense think tanks that monitor government spending are lying, Reuters is lying, and now apparently NATO Generals are also lying to support an American President many of them are at-odds with.

Do you hear yourself?

There's also a much simpler alternative explanation:
You have been lying to yourself because your beliefs don't match objective reality, so any time there's a contest between the two, your beliefs about reality are selected over what is plainly observable to people who do not suffer from TDS.

Ah, yes, nobody is ever trustworthy, at all or ever, whenever your ideology is involved.  Does that include you?

I am looking at what they actually do.  We, as-in "The United States of America", are sending weapons to Ukraine, they are receiving those weapons, and they are using those weapons against Russia.  The only difference now is that the Europeans are funding those weapons instead of American tax payers "donating them", because the Europeans are dead set on continuing the war in Ukraine indefinitely, despite the fact that it's now a stalemate and has been since before President Trump took office.

Nobody is "flaming" you, you're making statements directly contradicted by people in the American government, people in the European Union governments, people in NATO military commands, and even people fighting the war in Ukraine.  Everybody on this forum is a full grown man, not a child, which means they should be prepared to have their beliefs challenged.  Whenever any of us makes an assertion as if it were a statement of indisputable fact, that is directly contradicted by all available evidence, you can expect at least one of us to contest that assertion.  That is how grown men communicate.

Last but certainly not least, if you like your TDS, then you can keep your TDS.

GW,

The problem isn't with what you think you know, it's with what you think you know that just isn't so.  Start going to actual US government websites and news outlets that deliver actual news instead of leftist talking points and propaganda.

U.S. seizes sixth sanctioned tanker it says has ties to Venezuela in Trump's effort to control its oil

From 2025:
Trump’s Sanctions on Russia Are Serious—Enforcement Will Decide Whether They Work

From 2019:
On the record: The U.S. administration’s actions on Russia

52 separate actions against Russia during his first term in office, which was before the Russians decided to invade Ukraine while President Biden's underlings were in office.

You told me to ignore what they say and watch what they do.  Well, this is what President Trump's administration is actually doing- taking direct kinetic action against Russian energy exports to bring their economy to a screeching halt.  Sanctions haven't done as much as magical thinkers want them to because Russia is no longer trading with countries that care about enforcing our sanctions.  However, President Trump has applied even more sanctions against Russia, as-if direct kinetic action against them wasn't sufficient to inform Putin about how his administration feels about Putin starting a war against Ukraine.

You are uninformed, misinformed, or deliberately lying.  Which is it?

GW,

When you think you no longer have to convince anyone else that your ideas are correct, that's a character problem.

This is blatantly false.  Arresting people who have no legal right to be in America in the first place is in no way equivalent to what the KGB or Gestapo did.  The KGB and Gestapo didn't bother with judges and trials.  Unless you try to murder a federal agent, you still get a trial here in America, even as someone who doesn't have any legal right to be here.  If you do try to murder federal agents, then you should not be too surprised if they prove they're better trained and armed than some random street criminal.

If you truly cannot tell the difference, then that also is a character problem.  If you're pretending there is no difference, that's a much greater character problem.  If you disagree with the immigration laws as written, then urge your representatives to change them.  Democrats could've changed our immigration laws to mean anyone can come here at any time and for any reason, yet they did not do that when they had the House, Senate, and Presidency.  They could've granted citizenship to all the illegal aliens already here, but didn't do that, either.

President Biden's administration had years of time to do something more effective than what they did.  If winning the war in Ukraine was so important for America and NATO, then can you explain to the rest of us why President Biden's administration did nothing effective to win it while he was in office?

The rest of your fellow Americans have had enough of the Democrats' theatrical insanity, which is why you're getting Trump (again).  Quit voting for clown shows more concerned with which bathroom to use than whether or not our enemies are emboldened to attack after they get elected, and your Democrats might start winning elections again.

Oddly enough, we're no longer having problems recruiting and retaining enough personnel for our military.  You might want to ask them why they weren't willing to sign up under President Biden, but that requires a listening ear.  If you don't like what they have to say, then maybe you could take their place or convince your children to do so, if y'all feel that strongly about it.

How can Putin "win" anything in Ukraine when the European Union has an economy the size of the American economy, while Russia's economy is roughly the same as that of Italy?

Are you admitting that President Trump's assertions about the European Union being almost useless for fighting their own wars are correct?

If you were living under anything remotely resembling a dictatorship, then you wouldn't be able to champion the idea of staging an insurrection online without going to prison.  The simple and unavoidable truth is that there is no dictatorship here at home.  You're accustomed to an organized criminal syndicate we call "The Democrat Party" getting their way, no matter how asinine or self-destructive their ideas are for the average voter.  Now that their crime spree has been stunted because our government is merely defending against the worst of their behavior, you think the world is ending.

If you truly believe that any decision our government makes which you disagree with automatically equates to illegitimacy, then you're an anarchist who doesn't believe in rule of law.

This Stanford Torus structure artistic rendering from Nichlas Benjamin is more in line with what I had in mind for the exterior support rest of the habitation ring:

Except that I wanted a shape that maximizes usable floor space, which implies more of a D-shaped toroidal structure, like a tokamak.

The interior of this D-shaped tokamak is broadly similar to what I had in mind:

The structure would only be one or perhaps two stories high, with the bottom of the torus housing water piping and the top housing electrical power cables, data cables, and light pipes.

Try to visualize all those interior metal electromagnet "tiles" being replaced with cast basalt tiles:

The interior would be lined with cast basalt tiles like these:

Basalt can be cast into relatively complex shapes and has a strikingly beautiful natural appearance:

So, basic concept is as follows:
1. D-shaped torus to provide more usable floor space without an excessive number of floors requiring elevators, with reduced structural materials strength and therefore mass requirements, relative to a Super Dome.
2. Starship's 304L stainless steel is converted into a tubular exoskeleton / space frame.  The external frame is intended to allow for thermal expansion and contraction in the Martian temperature extremes between day and night.
3. Cast basalt tiles / blocks are inserted into the frame and sealed using Silicone caulk.
4. Liquid CO2 will be pumped through the space frame in an attempt to improve upon the room temperature strength of 304L, and to regulate its temperature to avoid excessive expansion and contraction.  We want to keep that stainless cold, definitely below zero, because it's weaker than A36 at room temperature, but not mildly cryogenic because we start to lose ductility and we definitely want to keep that.  We're after about 517MPa to 621MPa.  We don't go any colder than is required to achieve that yield strength.
5. The structure size / progression is ultimately limited by the number of arriving Starships.  We have around 70t of the right kind of material to work with per Starship.  The engines are higher grades of stainless that would be repurposed for making fasteners, tooling, and molds.

304L Temperature vs Yield Stress for Conventional 304L (green) and Laser Powder Bed Fusion (red):

Journal of Powder Materials - Ultra-Low-Temperature (4.2 K) Tensile Properties and Deformation Mechanism of Stainless Steel 304L Manufactured by Laser Powder Bed Fusion

As the graph above shows, laser sintering of 304 powder delivers high yield strength, partially due to formation of martensite, but we don't want martensite formation in a steel exposed to cryogenic temperatures, so we're sticking with a conventional cold-rolled seamless tubing material produced in a miniature electric arc furnace that accepts bits of recycled Starship hull scrap steel.  The yield strength mechanical property is reduced, but that other important metallurgical property, namely an austenitic grain structure which confers ductility at very low temperatures, is more important for our application than pure tensile strength, which we are "thermally improving" by keeping the steel cold using cold LCO2.

Seamless steel tubing generally offers superior strength-to-weight, as compared to rebar, so we should consider sending and using a machine to make tubing vs rebar to economize on material consumption required to build pressurized habitation volume.  A tube is not stronger than a solid rod with the same external dimensions, but it is stiffer (more resistant to deformation under load) for the same mass, so tubes provide more material to satisfy a given strength and stiffness requirement than solid rods (rebar).  So that ductility is not lost when cold soaked in the mildly cryogenic Martian night time temperatures, we will have to forego stronger grades of stainless in favor of austenitic stainless steels.  Starships are already made from austenitic stainless steel alloys, so this is not a sourcing problem.

Austenitic steels do not "dramatically strengthen" when exposed to thermal processes used to heat treat (harden / strengthen) steels with different grain structures, such as martensitic steels.  This makes them much softer and weaker than hardenable steels at room temperature, but they also do not become excessively brittle when exposed to extreme cold.  All steels become much stronger at very cold temperatures, to include austenitic steels, but unlike martensitic steels, for example, austenitic steels do not become so strong and hard as to behave more like a brittle ceramic than a ductile metal like low Carbon steel at room temperature.

In steels, strength and hardness are linked together, meaning you do not get one mechanical property change without the other.  You can surface vs through harden the steel, though.  The excessive hardness, not the significant increase in tensile strength associated with heat treatment or exposure to cryogenic temperatures, is the problem.   The austenitic 304L stainless is nominally a 28ksi Yield Strength material at room temperature, but chill it down to Martian night time temperatures and it becomes more like 100-150ksi.  This tensile strength improvement also makes the steel harder, but comes at the cost of ductility and toughness.  A hardenable martensitic steel like 300M (typically used in aircraft landing gear) starts out at 200ksi+ Yield Strength at room temperature.  Thermal soak 300M to Martian night time temperatures and tensile strength becomes something stupidly high, in the range of 300-500ksi.  If improved tensile strength was the only mechanical property change, then nobody would ever use austenitic steels for cryogenic propellant tanks.  The problem is that the dramatic increase in tensile strength is accompanied by an equally dramatic increase in hardness that makes 300M behave less like steel and more like a ceramic when subjected to an impact loading.  Very hard materials do not easily deform and then spring back into shape.  When a steel as hard as 300M already is at room temperature, is accidentally struck by a rock after being cooled to mildly cryogenic temperatures, it will likely fracture or shatter like a ceramic pot.

We see this same behavior exhibited by very hard armor steels and high yield ship building steels at Earth-normal temperatures.  When the material is struck after exposure to arctic-like temperatures, it can fracture or shatter, especially near weld lines.  Ice breakers use special grades of steel in their hulls that do not become quite as strong and hard when cold soaked.  The modified steel grain structure won't be as strong and hard at room temperature as "normal" ship building steels a result, but increased strength and hardness at lower temperatures partially compensates.  When that is not enough, thicker hull plating is used when colder service temperatures alone do not imbue the steel hull plating with insufficient tensile strength and hardness to meet the structural requirements for the ship's hull.  Ordinarily, ice breakers use thicker hull plating by default to enable them to strike and break-up surface sea ice so that commercial ships fabricated from lower cost Carbon steels can then transit arctic waters without substantial hull reinforcement and using more expensive grades of slightly weaker specialty steels.

On Mars, we have no real choice but to accept cold soaking at night, which means we need austenitic steels for construction.  However, we could thermally regulate the steel tubing structure's temperature by filling it with liquid CO2 and using it as part of the colony's habitat thermal regulation radiator system.  This is just an example, since the strengthening and hardening of any steel alloy is not a straight line as service temperature decreases.  However, if keeping the LCO2 inside the structural tubing at a "balmy" -50F vs -100F, also managed to keep the 304L's yield strength in the 65-75ksi range, then it becomes a "more ideal" structural steel that retains greater ductility.  65ksi is about the same as annealed 4130 chrome-moly tubing used in aircraft construction, so obtaining the associated tensile strength and hardness "bump" over 304L's room temperature mechanical properties would make it very suitable for construction purposes.  There's obviously a non-zero risk of a CO2 leak inside the habitat dome from using the structure this way, so other engineering considerations must be taken into account.  Still, it's an interesting idea with the potential to reduce material consumption while creating a lighter but stronger structure using what is otherwise a "weak" structural steel.  Perhaps it's only a suitable structural reinforcement and material economization concept for greenhouses used to grow food for the colony.  This was a "work with what you got" vs "work with what you wished you had" idea, and maybe it won't work at all for any number of technical reasons.

RobertDyck,

You're the one making claims about a system that never once flew aboard the Arrow, so do that yourself.  If you can't find anything, then all you have left is pure belief-driven speculation.

I've provided independently verifiable facts and evidence based upon publicly released historical data.  Every assertion you've made thus far has been refuted by available evidence.  Whether or not history offends your sensibilities is not my concern.

The basis of my last post is, nobody had a functional BVR missile and fire control system in 1958, therefore your claims about how good Arrow / Astra / Sparrow could've been are emotionally-driven and evidence-free.  Your feelings towards the Arrow override your ability to do basic math, recognize faults in your logic, admit when historical evidence disagrees with your assertions, and view the Arrow program as the developmental failure that it would've become, had Canada pursued it to the point of complete failure.

America did pursue a Mach 3 interceptor to the point of complete program failure.  YF-12A was a true Mach 3 interceptor by recorded flight speed data, but was never an operational system specifically because its radar and missile technologies were far too immature.  All the same radio electronics companies were involved in the development of Astra, ASG-18, and GAR-9 / AIM-47 programs.  What should a rational and logical person make of that?

SN 60-6935, the only surviving YF-12A, was flown to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, 17 November, 1979.

My take is that the tech simply wasn't ready for operational use, and no amount of speculative belief will ever change that.  It just barely worked when maintenance time was irrelevant and every test was scripted to the last detail.  When the AIM-54A was used in more realistic tests 10 to 20 years later, the significant limitations of missiles using tube-based radar electronics were plainly evident to all involved.  This may not sit well with F-14 and Phoenix missile enthusiasts, either, but that was ugly operational reality.  When such weapons did work under combat-like conditions, they never hit their assigned targets more than 50% of the time.  If you fired a pair of Phoenix missiles at a target, then you'd get a kill more often than not.  Unless you're here to claim that 1950s tube-based electronics were more reliable and functional than the mostly solid state AWG-9 and AIM-54A, then any counter-factual line of argumentation is pointless.

I cannot find any recorded historical evidence that RCA's Astra-1 ever flew aboard a test aircraft, so any claims about what it could achieve do not appear to be based upon recorded test results.  RCA lost the ASG-18 contract to Hughes in the spring of 1957 for lack of progress.  Arrow enthusiasts would have picked up on this and added it to their Arrow lore if it did.

The MA-1 radar and fire control system, which was installed on every production F-106 airframe, weighed in at 2,520lbs.  It could lock-up a B-52 at about 40 miles, subsequently extended to about 69 miles following electronics upgrades that came many years later.  In clear skies, the IRST system had a longer tracking range than the radar ever did, and was used as secondary confirmation against radar-located targets.

I can tell you that back in America, Sperry was replaced by RCA in 1956, then RCA was replaced by Hughes in 1957.  RCA was replaced in 1957 because their radar could not meet radar detection range targets of 100+ miles and insufficient progress was made for continued funding.  Why it is that the RCAF thought they eventually would is beyond my understanding.  Hughes was finally able to hit their contractually obligated radar detection range targets.  Development work continued until 1966 when the F-12B was canceled by the USAF.  In short, nothing remotely approaching a "ready-to-use" radar and fire control system existed until long after the Arrow was cancelled.  ASG-18 was designed to fit inside a 40 inch diameter nose, which both the Arrow and YF-12A shared, and both employed a weapons system officer to operate their radar / fire control equipment and launch missiles.  The ASG-18 radar alone weighed 2,100lbs.  As with RCA, Hughes also posted significantly greater theoretical detection and tracking distances, but in operational practice it could lock-up bomber-sized target around 100 miles- same max range as the missiles it was paired with.

Edit:
I should have stated that the ASG-18's 40 inch diameter radar dish was designed to fit in the Arrow and YF-12A nose.  ASG-18 and GAR-9 were first tested aboard a modified B-58 Hustler, and subsequently installed in the YF-12A.  There was some talk of putting ASG-18s in F-4s after the F-12B was canceled, but the largest diameter dish for radars installed in F-4s were the 32-inch dishes associated with the APQ-72 and later partially (AWG-10) or fully digital (AWG-14) equipment.  I don't think a 40 inch dish would fit in the F-4's nose without significant modification and aerodynamic penalties.  AWG-9 radars fitted to F-14s had 36 inch diameter dishes.  I remember seeing those aboard the carriers I served aboard.  AWG-9 was the most powerful radar fitted to an American fighter aircraft until the F-22's APG-77 entered service around 2005, but APG-71 radars fitted to F-15s were likely even more capable, not due to peak power output, but vastly improved digital signal processing capabilities.  I do know that AWG-9 was about 15X more capable of volume search than the most capable F-4 radars.

MTBF for many thousands of discrete electronic components was about 150 hours, so constant maintenance in operation was a near-guarantee.  IIRC, certain radar components required liquid cooling systems, same as the AIM-54A.  From what I understood, the specialized thermal batteries and liquid cooling systems were what limited availability and reliability of Iranian purchased F-14s and AIM-54As.

My pure speculation is that had the advanced flight control features of the Arrow and ASG-18 become part of an operational system, total system weight would fall somewhere between 2,500-3,000lbs.  That means every bit of the engine mass savings provided by the Iroquois engines would've been consumed by the new digital fly-by-wire flight control system, radar, and fire control systems.  Worse than that, AIM-47 was about twice as heavy as Sparrow II, so Arrow would've carried 2 of those missiles at most to remain at MTOW with full internal fuel.  If AIM-54A performance was any indication, that means each Arrow could nominally shoot down a single bomber under combat conditions when equipped with 2X AIM-47A missiles.  If Arrow was equipped with 3X AIM-7E, which also didn't exist until many years later, then it could statistically shoot down zero bombers.  If equipped with 6X AIM-7E, then Pk = 0.48, so perhaps every other Arrow would manage to kill one bomber after a pair of Arrows expended 6-9 missiles per bomber, or maybe not.

Is that really what you wanted to bet the continued existence of your cities on?

America "bet", if you will, that we could build enough early warning radars with integrated GCI for use in conjunction with simplified interceptors to close to within visual range of a bomber and shoot them down using heat-seeking missiles, rockets with small nuclear warheads, or cannon fire, because that was the extent of what 1950s electronics could accomplish with any degree of reliability.  This system, as limited and flawed as it was, also conferred the unintentional benefit of actually knowing what you were shooting at.

RobertDyck,

I'm patiently waiting for a response demonstrating basic understanding of aerospace design tradeoffs.

Why didn't Canada, France, and the United Kingdom pool their design and manufacturing resources, post-WWII?

There seems to be very limited economic trade value, even today, most of it defense-related.

Why doesn't the UK buy metal ores from Canada, for example?

CF-105 was a remarkably good airframe design, but Iroquois was a remarkably inefficient engine design, even for the late 1950s.  By the time the CF-105 flew, the J58 was accelerating 40% less air mass while producing 14-25% more dry thrust and 13% more thrust in burner.  If that's not indicative of a fundamental engine design problem, then I don't know what qualifies.

America doesn't have any issue with purchasing foreign weapons, despite spurious claims to the contrary, but when your design can't meet key performance metrics, it doesn't get purchased.  Engines need reasonable-for-their-time fuel economy when compared with similar American engine designs, not simple thrust output.  When we evaluated how poorly Iroquois engines did on fuel economy, they weren't worth further investment.  We already had more fuel efficient engines with similar thrust output (J58 or J93).  If we were going to design a combat jet around an engine, as all of them are, then we would expect a foreign design to demonstrate parity with American engine designs, and preferably an improvement over existing American engines.  Iroquois was not an improvement, so it was never considered a worthwhile foreign defense engineering project for our government to fund.

If Iroquois was able to demonstrate J58 / J93 thrust output with improved TSFC, I would bet almost anything that we'd fund further development, regardless of what the Canadian government did with their Arrow program.  Throughout the Cold War, the most notable design detail pertaining to British, Canadian, and French fighter jet engine designs was how fuel-inefficient they were, relative to American engines, which is why we rarely bought any.  Now you see quite a few British engines powering American combat aircraft, because they are actual improvements relative to contemporary American engine designs and, beyond geopolitical considerations, that's why we purchased them.

America's Air Force really liked the CF-105 as a platform and concept, but in practice none of the weapon systems or electronics to enable it to function as a self-directed BVR interceptor were remotely close to being ready for combat use.  Nobody had a reliable and operationally usable BVR radar and air intercept missile combination until the 1980s.  For the F-106s that America did purchase in limited numbers, more than a few were lost to accidents, but none of them were used in combat to perform interception missions.  The only combat jet designed in the 1950s which was not well on its way to the bone yard by the 1980s was the B-52, so America would've purchased fewer CF-105s vs F-106s for that same role and then had a more expensive F-106 with nearly identical actual vs envisioned capabilities.

There might have been orders for 180 aircraft for America and 40-60 from Canada, so 100 fewer tails than actual F-106 production.  What actual good would that have done for America or Canada?  The British had already abandoned the dedicated interceptor role by the 1960s when they realized before Americans did, just as Canadian military leaders did, that radar and missile tech was nowhere near good enough.

The F135 engine has almost as much dry thrust (28,000lbf) as the Iroquois has in full afterburner (30,000lbf).  In full afterburner, the F135 (43,000lbf) has 43% greater thrust than the Iroquois.  F135 OPR is 28:1, 324lbm/sec mass flow rate.  Iroquois OPR is 8:1, 420lbm/sec mass flow rate.  That means the F135 will have significantly better fuel economy at any power setting.  There's nothing "remarkably close" about them.

Mass flow rates for American fighter jet engines only vary between 140lbm/sec (J52) and 325lbm/sec (F135), from the mid-1950s to the present day, with the tiny J85 that powered the F-5 and T-38 being the only outlier.  This covers J52, J58, J75, J79, J93, TF30, TF41, F101, F110, F404, F414, F119, and F135.  Higher mass flow rates without significant thrust increases are always indicative of inefficient designs.

The closest Iroquois size and weight analogs were the J75s, but J75s still have 12.5:1 OPRs and 260lbm/sec mass flow rates, with maximum thrust being 29,500lbf (J75-P5A) vs 30,000lbf (Iroquois).  OPR is a major factor in jet engine fuel efficiency, so at max dry thrust the Iroquois was burning an additional 4,050lbs/hr (596gph) at sea level.  For equal thrust, Iroquois was still burning an additional 1,925lbs/hr (283gph).  Afterburning TSFC figures between J75 and Iroquois are quite similar.  This is unsurprising since thrust is also nearly equal.

Any engine ingesting 60% more air mass to achieve the same max thrust output will be fair to terrible in terms of TSFC.  The minor thrust improvement of the Iroquois engine over the J75 was accompanied by a significant fuel burn increase.  That was why Iroquois was never installed in any other fighter jets.  Iroquois was an obsolete design by 1958.  It's a scaled-up J79 in terms of fuel burn rate, except that a scaled-up J79 would have J75 fuel burn rates.  The J58 turbojets that powered the SR-71 were also more efficient, and capable of producing more dry (25,000lbf) and wet (34,000lbf) thrust, at reduced fuel burn rates, when the air intake was appropriately sized.  The SR-71's intake design limited installed thrust because it was deliberately designed for Mach 3 flight speeds at 70,000ft, which meant most of the intake area was "blocked" by its variable geometry inlet.  Despite the dramatic loss of thrust at speeds below Mach 2 for the installed J58 engines, the increase efficiency and suppression of compressor surge at Mach 3 flight speeds was worth the tradeoff for a recon plane flying straight and level at 70,000ft at Mach 3.  Nobody wanting better takeoff to Mach 2.5 thrust and acceleration would ever design their engine inlets the way the SR-71's inlets were designed.

Nothing Was Leared YouTube Channel -  White Liberal News Good For US Means Bad For Us ep 103

"Join us next time when we tell you how much better we are as liberals than everyone else." - Karen

tahanson43206,

Using materials like Alumina and BNNT, it's feasible to produce SCO2 engines with 1,300C TITs and 66% thermal-to-mechanical efficiency, with the weight of Aluminum metal and both absolute strength and strength-to-weight far surpassing any Inconel super alloy at 1,300C.  At that point, there's little to argue over the benefits of this technology.  It will be smaller / lighter / stronger / longer-lasting / more thermally efficient than any competing thermal engine technology.  It's rapidly becoming a close runner-up to Solid Oxide Fuel Cells, but at much greater power density.

Reliable direct conversion (of hydrocarbon fuels) SOFCs are now approaching 5kW/kg in commercialized applications, and they achieve 70% to 80% thermal efficiency.  I've read about lab-scale test articles achieving 8kW/kg.  Plate-out of the electrodes and destruction of the membranes from Sulfur contamination continues to be a problem, although use of Methane vs denser fuels (Propane, kerosene, diesel) ameliorates this problem.  SCO2 gas turbine engines are capable of power densities about 20X that of SOFCs by using CMCs combining Alumina with advanced fiber reinforcements like BNNT.

Do you see those big white components in these gas turbine engines?:

Those are Alumina-based CMCs.  They're ceramic fiber reinforced metal oxide matrix composites (Alumina binder with Nextel fibers or something similar) with some plasticity to them, meaning they behave less like glass rods and more like sheet metal, but with significant thermal shock tolerance.  They're not stronger than metals at room temperature, nor harder than pure ceramics, nor stiffer than Carbon fibers, yet they have a highly desirable mix of those properties combined with greater tensile strength than super alloys at combustion temperatures.  Did I mention how light they are?  They're similar in density to Aluminum.  Even after hundreds of hours of operation, they still look brand new, because they're already oxidized to the point that no additional oxidation is possible.  Have you ever noticed how metals exposed to such extreme temperatures look "rusted" or "blackened" or "every color of the rainbow"?  That is actually surface oxidation damage to the base metal alloy.  After a certain amount of accumulated oxidation damage, they become scrap metal.

A master's level thesis on testing these materials:
All-Oxide Ceramic Matrix Composites - Thermal Stability during Tribological Interactions with Superalloys - Daniel Vazquez Calnacasco - Luleå University of Technology, Department of Engineering Sciences and Mathematics

A NASA CMC Development Partnership Project with Rolls-Royce and COI ceramics:
[url=https://ntrs.nasa.gov/api/citations/20150018257/downloads/20150018257.pdf]OXIDE/OXIDE CERAMIC MATRIX COMPOSITE (CMC)
EXHAUST MIXER DEVELOPMENT IN THE NASA ENVIRONMENTALLY RESPONSIBLE AVIATION (ERA) PROJECT[/url]

The very last slide shows pictograms of the process steps that COI Ceramics uses to make these parts.

Anyone who wants to see practical hybrid-electric aircraft take flight should be onboard with this tech, because every other energy storage and conversion technology is a pretender to their cause.  At the present time, there are no electro-chemical batteries or fuel cells in existence that come within a country mile of the power-to-weight requirements for modern long range turbine-powered and kerosene-fueled aircraft.

Seeing designs with 20-30% increase in fuel economy over existing conventional gas turbine powered aircraft would be pretty spectacular.

This comment from Reddit User "discombobulated38x" is one of the best simplified explanations of current large turbofan engine design that I've seen in awhile:

Grainger Istitute for Engineering - University of Wisconsin at Madison - Raytheon Technologies Research Center - Additive Manufactured Supercritical CO2 Heat to Power Solution - June 8, 2022

With a 1,300C TIT, they're talking about getting 66% thermal efficiency.

That would be a very significant step-change for marine and aircraft propulsion systems, and across a very significant power output range.  The most efficient conventional large turbofan engines are 46% thermally efficient, but only at maximum thermodynamic output.  Extracting two-thirds of the mechanical energy out of the total available thermal energy in every kilogram of fuel burned would be a stunning achievement for gas turbines.  For a 1GWe power plant where all of the core plant components easily fit on perhaps 5 semi trucks, that is jaw-dropping performance.

I will always be a sailor at heart, so I think of it this way:
An 80,000t to 110,000t aircraft carrier nominally requires 208MW of power to move at 30+ knots.  SCO2 gas turbines would be so light and compact that the ship could have a quadruple redundant power and propulsion plant, such that each of the four plants can propel the ship at maximum speed.  Destruction of 3 out of 4 power plant compartments from bomb hits wouldn't slow the ship at all.  Each plant is so much smaller than a steam plant that it can have its own armored engine compartment at the aft end of the ship, because the equipment has a very minor effect on how the ship sits in the water.  The steam plants were so large and heavy that the entire hull from about amidships aft, just below the waterline and all the way to the keel, was filled with various boilers, engine rooms, steam piping, shafting, and backup diesel generators.  With a SCO2 propulsion system, the gallery deck, which is situated just below the flight deck and above the hangar bay, could be almost empty except for the aircraft catapults and arresting gear.  There would be no need to put squadron ready rooms there, staff workspaces, and berthing compartments, because most of the hull would be a cavernous empty space available for the air wing personnel.  This would reduce the carrier's metacentric height and improve stability following battle damage.

For aircraft, existing airframes could just about double their cruising range for no increase in fuel load or engine weight.

I don't know how other people think about those kinds of performance improvements, but I consider them to be a "step change" in engine capability.