New Mars Forums

This link covers some of the ceramic fibers being used in these parts:
Oxide-oxide ceramic matrix composites enabling widespread industry adoption

I would be remiss if I did not mention the role that NASA's and DOE's partnership programs as the genesis for the commercialization of a lot of these lab curiosities.  Science for its own sake still matters, but so does directed science, aka "engineering", aimed at solving real world problems.  NASA helps industry develop the basic "know-how" to retire risk to begin to apply aerospace technologies to the ordinary everyday world that the majority of us inhabit.

RobertDyck,

President Trump is gone in 3 years.  There are presently at least 20 times more F-35 airframes and components being used every day than there are Gripen-Es in the entire world.  By the time Canada quits dithering on their purchase decision, President Trump will no longer be in office.  You should know that because Canada already makes parts for the F-35.  They've never made, repaired, or alternatively sourced any spare parts for a Gripen.  Building a domestic supply chain for Gripen parts will take the better part of a decade, by which time the rest of the world will have 6th generation fighters in service.  When all the BS about performance is shown for exactly what it is, you won't have anyone to blame except yourselves.  This has been a running theme with Canada since the Avro Arrow.

As hilarious as it would be to watch Canada operate Elbonia's Air Force, I actually think more highly of you than you do of yourselves, apparently.  There isn't a first rate Air Force in the entire world which is not developing stealthy aircraft.  Either everyone but Sweden is stupid, or they know exactly what stealth means in the context of tactical fighters and are working as fast as they can to "catch up" to modernity.  Why do you think the European Union nations are working on their own stealth fighters?

Your country is contemplating purchasing fighters that have been rendered obsolete against modern air defense systems and air superiority fighters, all to thumb your noses at one man who will be gone in 3 years time.  Nostalgia doesn't win any fights against similarly capable opponents.  Good luck.  You'll need it.

What European Fighter Jets Have Critical US Components?

tahanson43206,

The portion of the design work that requires truly advanced engineering capabilities is modeling of the turbine's dynamic behavior during ramp-up / ramp-down.  You need a supercomputer to do this.  Trial and error won't cut it.  The reason SCO2 gas turbines didn't exist until about 25 years ago was this exact problem.

Chemical Vapor Deposition works on pretty much any part you can throw in the tank.

Easily.  Google "3D printed SCO2 turbine components".

3D Printing Turbomachinery for Super Critical CO2 Systems - Hanwha Power Systems achieves 80% faster build time and 90% less material with VELO3D's Sapphire

SwRI study examines oxide growth in additively manufactured metals in sCO2 environment

Design, Fabrication and Testing of Novel Compact Recuperators for the Supercritical Carbon Dioxide Brayton Power Cycle

Nobody is trying to hide the progress being made on this tech, it's simply not widely reported on.  America, China, the United Kingdom, South Korea, Japan, and various other Asian and European Union countries are all working on this technology.  It's an area of active development.

The most significant technical challenges are:
1. Modeling turbine flow behavior with SCO2- you really need a supercomputer to do this, and AI would probably help some more
2. Using the correct refractory materials with well-matched CTEs (this actually took quite a bit of experimentation)
3. Modeling and fabricating the heat recuperators and air separator units (for power cycles that use enriched O2)- advanced machining such as chemical etching, diffusion bonding, and selective laser metal sintering are used here, because these units are not like "tube and fin" models used by steam turbines or other more common heat exchangers
4. Long term failure mode analysis with significant thermal gradients and CO2 impurities at-play
5. Selection of appropriate sealing and lubrication materials.  This is challenging, but not impossible.

RobertDyck,

Weren't you the one endlessly advocating for sending weapons to fight the Russians in Ukraine?

Now that America is directly and actively pushing back on Russia by hitting them where it hurts most, you're shocked that we did it?

Greenland Courts China in Snub to Trump

Is the Polar Silk Road a Highway or Is It at an Impasse? China's Arctic Policy Seven Years On

China’s Arctic Policy - The State Council Information Office of the People's Republic of China - January 2018

Rand Report - China's Economic, Scientific, and Information Activities in the Arctic - Benign Activities or Hidden Agenda?

Steam vs Supercritical CO2 Power Turbine Size Comparisons:

The 1GWe SCO2 power turbine will easily fit on a single semi truck.  The 1GWe steam turbine?  No chance of that ever happening.

Toshiba's 25MWe Allam cycle SCO2 Power Turbine and Combustor Cutaway:

The extra casings surrounding the power turbine are there to recirculate hot CO2.

Edit:
This is a waste heat recovery turbine size comparison between SCO2 and steam:

One of those devices is clearly much smaller than the other.

Steam turbines typically have many many blades that must be very carefully weighed and assembled in a specific order to maintain the balance of the rotating assembly.

SCO2 turbines tend to be machined from monolithic blocks of refractory metal alloys, formed from 3D printed powdered / sintered metal, or precisely cut using wire EDM.  This is practical because even 1GW SCO2 power turbines are so small compared to steam turbines.

tahanson43206,

Gas turbines and heat recuperators that are 10X smaller than steam equivalents are not an "almost negligible advantage".  All that metal and machining costs real money.  Even if the steel grades used in a steam turbine are modestly cheaper, they're not 10X cheaper than the steels used in SCO2 turbines.  The difference in sizing of the major pieces of plant equipment are "the entire city block" vs "one house on the block".  All the stuff in one house can be crammed into a Starship and shipped to Mars.  Shipping an entire city block's worth of equipment is not practical.  There is no reality-based scenario where any kind of steam turbine comes close to out-performing the SCO2 turbine.  It's not cheaper, it's not smaller, it's not easier to repair, it's not easier to assemble and disassemble for transport, it's not faster to ramp-up and ramp-down to load-follow, and it's definitely not minimizing CO2 emissions.

China National Nuclear Corporation already has their first grid-connected SCO2 power plant in Guizhou.  It's very small, only a pair of 15MW waste heat SCO2 turbo-generators, but that waste heat was otherwise at the wrong temperature for using steam, because it was waste heat from steel making.  Would you rather they burn more or less coal?

The first generation of any new technology will take time to establish its footing.  I don't judge combustion engines on the relative success or failure of Ford's Model T.  That engine and vehicle was a joke compared to any modern turbocharged inline 4 cylinder engine in a mini SUV.  Modern I4's produce as much horsepower and torque as a muscle car era V8, at less than half the weight and displacement.  Modern family vehicles are only possible because their turbo I4's deliver V8 torque and power at half the size and weight, all day long.

This article does a good job of indicating exactly how the Allam-Fetvedt Cycle works, why it's a significant improvement over what we presently have in the form of steam and conventional gas turbines, and why Net Power is pursuing it, despite cost overruns and delays, which are related to problems with the Air Separator Units, rather than the SCO2 gas turbines and heat exchangers:
This Power Plant Runs on CO2

One of the reasons it's "good far Mars", is that it recaptures and recirculates the exhaust effluent, instead of dumping it in the atmosphere.  It's the first power plant to demonstrate it can do that economically, meaning so much of the power isn't consumed trying to recompress the CO2 for storage that it's not worth the cost and energy involved.  It's a CO2 recycling system deliberately built into the power plant as an integral design feature, rather than as an afterthought.  Those Air Separator Units will also become critical life support infrastructure pieces for a Mars colony.

If it's not apparent yet from the photos provided above, all the "real money" spent on the F-35 program was dumped into the sensors and software to provide a "bubble" of spatial awareness, plus the computer program telling the pilot what to pay attention to and what can be safely ignored.  That's why it took so long to fully develop.  It had almost nothing to do with the flight control software or engine or airframe, even though all of those things are their own little technological marvels.  There is no other aircraft in existence that provides the same level of situational awareness as the F-35, to include the F-22.

We don't pay lip service to the idea of going back and fixing defects in components or software, either.  When we discover that something is broken, we commit to solving the problems until it "just works".  Denying that problems exist or hoping your enemy doesn't discover the flaws in the system is not an acceptable way to do business.  To their credit, Lockheed-Martin has worked with their team of contractors to find and fix all observed airframe, engine, and software problems.  Does it take them longer than we'd like it to?  Yes.  Is it cheap?  No.  Does it mean we have confidence that the platform is ready for combat by the time it sees combat?  Absolutely.  All effort is now directed at future enhancements and meeting the production (16 new tails per month) and repair schedules.

If you are not aware of what is going on around your plane at all times, against anyone who has a plane with the F-35s capabilities or modern air defense systems, you're as good as dead.  If someone hasn't come along to kill you yet, that's because you had no serious effect on their operations.  To this very day, most pilots who were shot down were either completely unaware that they were under attack, or so lacking in basic information about the direction that the threat was coming from that they couldn't do anything about it.

Here in the West, we spend so much time and effort training fighter pilots that we cannot afford to forfeit their lives, simply because some electronic gadget that could provide threat and target awareness wasn't installed in their jet due to cost-cutting measures.  We need them to survive their first 5 to 10 combat missions to gain the experience required to operate in the new threat environment.

If they fly prior generations of combat jets, then half of them get shot down on every mission they fly against enemy air defenses and fighters in virtually all of the war games conducted during the past 25 years.  Statistically speaking, that means none of them live long enough to see the end of their first combat deployment.  Nobody is left to train the next replacement group of pilots.  Worse than that, the production rates for modern combat jets are so low that there won't be replacements available in any meaningful period of time.  Absent complete destruction of enemy air defenses, an entire squadron of Vipers or Strike Eagles or Rafales or Typhoons could be lost on a single mission over heavily defended territory.  There's no way to conjure up replacement jets and aircrew.  Anyone who isn't already in the training pipeline is unlikely to see action before the war is over, and there are never enough tails once the shooting starts.

China is producing about 200 J-20s per year as of 2025, so only 16 planes per month spread across 5 different production lines.  Even for China it would now appear that there's a hard limit on resources devoted to any one piece of military equipment.  Russia hasn't even come close to replacing combat-related aircraft losses in the Ukraine War.  There's no reason to believe that America, China, Russia, or anyone else for that matter, ever could.  These combat jets are no longer Aluminum sheet metal bent into shape and riveted.  The tooling to make the airframes runs well into the tens of millions of dollars, and their engines are "OMG" expensive.  Trained and efficient production line workers cannot be summoned from the talent pool, either.  If money is no object, then sure, we could spend a major portion of GDP to produce more jet engines, but that is now as unrealistic as thinking you can afford to lose half your fighter jet squadron per mission.

Oddly enough, the Chinese are also starting to accept that this is how modern air combat really works.  They have just as many problems with training / retaining new pilots and meeting production schedules as we do.  They're not churning out their new J-20s or J-35s any faster than we are, and for the same reason.  These machines are hideously complex.  Each one is now so costly as to almost become a strategic asset.  Losing them to human error, inadequate training, or limited survivability in the threat environment are no longer viewed as practical, even during a war.  If you fail to swiftly establish air superiority and use it to wipe out the enemy's war machines, then you'll fight a desperate grinding war of attrition until one side breaks under the constant pressure, and that process could take years.  All the while, you're losing young men at frightening rates, money is being burned like there's no tomorrow, and in a very real sense, the opportunity cost of having the war drag on is more economically damaging than the deaths and national debts because it can keep taking from your people generations after the war is over.  I've yet to see ships produced quickly and effectively when the shipyard was under cruise missile attack, either.  The WWII production methods don't work with modern weapon systems.  The "quick and dirty" substitute weapons are iron bombs and artillery shells, which means you have to get close enough to use them.  Whoever is able to control the skies is going to dictate which pieces of military equipment remain usable.  Knock out the oil refineries or power plants and the entire war machine grinds to a halt.  Here in America, we've determined that we cannot afford to allow that to happen to us, so everything we develop for the air power domain is to ensure that happens to our enemies first.  Attrition warfare is a losing proposition, as both WWI and WWII already proved.

Lest we forget our automotive history, here are a few images of the Chrysler recuperated gas turbine car engine:

Engine installation at the factory:

Flow Path / Operating Diagram:

Recent photos of the engine and transmission:

Older photo of the intake side:

Engine Diagram:

Vehicle Powertrain Diagram:

Chrysler went through 7 generations of gas turbine engine technology in an attempt to make the tech reliable, durable, affordable, and fuel efficient enough to be worth manufacturing for the general public.  Unfortunately, their efforts never resulted in a saleable product.  When Lee Iacocca took the bailout from Uncle Sam, part of the deal was to kill this program because Chrysler sunk a huge amount of their R&D budget into its development.

General Motors had their own turbine powered concept car, but again, development was insufficient to result in a saleable product.

Jaguar attempted a gas turbine electric powered car, also amounting to nothing.  A few prototypes were built and tested, nothing more.

As an electric hybrid using a micro gas turbine + small battery + electric traction motors, the concept actually makes a lot more sense.

The LearJet bubbas worked on this thing:

In the 1960s, everyone thought gas turbines would power everything:

Bill Bessler built a steam powered car for General Motors in the 1970s.  It's primary claim to fame was dramatically reduced smog emission prior to catalytic converters, but fuel economy was only 15mpg.  Dutcher worked on a steam powered car for California in the 1970s as well.

US DoE tested a Stirling engine car in the 1980s to early 1990s:

Could we get better performance from gas turbine an external combustion engines using modern FADEC technology?

Probably.

Will they ever be as cheap and cost-effective as piston engines at output below about 550hp or so?

Possibly, but not likely.  The materials and manufacturing methods used to deal with the heat are expensive, full stop.

tahanson43206,

I'm not sure if he understands how significant the friction and Reynolds losses will be in the sort of machine he's proposing.  Have you noticed that all geared turbofans use reduction drives to power the fan or prop, but nobody puts anything like what he's envisioning in the hot section of the turbine where the hot gas is expanding?  Gears, hinges, and whatnot in the part of the machine that's hot enough to melt Iron typically don't last very long.  The only reason hot section components don't melt in modern turbines is that they use boundary layer cooling, thermal barrier coatings, and smooth flow through the core.

If someone thought they could extract significant additional power, they'd not-so-simply work out how to make a mechanical advantage device work.  Even in the context of steam turbines operating at more survivable temperatures, said mechanism is still likely to fail.  There are basic fluid and thermodynamic phenomenon that would "sap power" from the device he wants to create, even if the mechanical bits don't overheat and warp.

While it may not be technically impossible, there are easier and simpler ways to extract more power from expanding gas.  This kinda reminds me of the Librato (sp?) engine.  That guy actually built one, and technically it was more thermodynamically efficient than a conventional diesel piston engine due to the mechanical advantage the mechanism provided, but it also vibrated itself to death when scaled up, even though it kinda sorta worked at a very small scale.  There have been all manner of novel mechanical advantage engines designed to extract additional power, but most of them end up being more trouble than they're worth.

Whenever engineers want to increase energy conversion efficiency, they increase the temperature delta and/or add another row of blades to the expansion turbine to extract more power.  They stop when the mass / size of the expansion turbine becomes impractical, and instead use the hot exhaust effluent to flash water to steam to run a geared steam turbine in a secondary power transfer loop.  This is a good system for a stationary power plant of even a ship with a high quality heat source, such as a gas turbine engine.

Chrysler used a large recuperator stage to make their automotive gas turbine more efficient because more turbine blades were and are expensive, but had to stop when the thing filled the engine bay.  They also used "blade disks" or "blisks" vs traditional individual turbine blades, because a blisk is a single near-net-shape casting which minimizes finishing machining operations.  At 410lbs, the turbine was still lighter than an all-Iron V8, but not by a lot, it burned a more expensive fuel, even though it could technically run on Chanel No 5, and on top of that it was made from precision machined refractory metals that could not be repaired by shade tree mechanics.  Fuel economy at idle with a gas turbine is horrific, even today.  The turbine engine ultimately made 130hp and 425-450lb-ft of torque.  The torque was phenomenal for the time, so acceleration to highway speeds was very respectable, but total power was also very limited.  Once you're on the highway, passing a slower driver is more difficult.  It would've been fine for 55mph, but passing someone at 70mph going up a hill would be difficult.  Unfortunately, all of the materials tech added up to an engine that was much more expensive than an equally capable gasoline fueled piston engine.  I think it would still be more expensive using modern manufacturing tech.  Modern piston engines are mostly cast Iron moving bits / Aluminum for blocks or heads or covers / plastic for intake manifolds since it heats soaks less than Aluminum.  Those are the cheapest and lightest materials that get the job done, and they do the job admirably.

The all-Aluminum LS1 V8 engine from the turn of the century made 305-350hp and 335-365lb-ft of torque.  The most modern 6.6L L8T version of the LS engine architecture makes 401hp and 464lb-ft of torque.  These all-Aluminum engines also weigh about 400-425lbs, fully dressed, without fluids.  They're weight-equivalents of that Chrysler turbine, about the same size, make considerably more power, burn less fuel, burn gasoline instead of kerosene or diesel, and don't cost nearly as much to manufacture as a gas turbine because nearly every part of the engine is a casting or powdered metal part or plastic.  Modern casting and powdered metallurgy is so good that it's considerably stronger than the more expensive low-alloy steel forgings from the muscle car era.  The factory forged crankshafts and connecting rods from the muscle cars are not as strong as the modern stuff.  We used so many forgings for so long for sake of consistency of forged parts.

We quit considering small gas turbine engines because of the aforementioned idle fuel consumption problem combined with the fact that none of them are significantly lighter or smaller than equivalently powerful piston engines.  Modern turbocharged I4s are cranking out 200-250hp and 250-350lb-ft of torque and only weight about 250lbs with fluids and accessories.  Gas turbines can be made lighter, but only when idle fuel economy, service life, and cost considerations are tossed out the window.  Gas turbines still work great for mostly steady-state applications like aircraft and electric power plants.

If both range and supersonic speed are all-important, then why was the F-111 never adopted by Canada?

The TF-30 engines are significantly larger in diameter than the F-135, so a pair of F-135 engines should make it climb like the F-14D.  I've never heard anyone claim that a Tomcat couldn't climb well.  F-111F's initial climb rate was almost 26,000fpm, so increasing thrust by 71% should provide a 45,000fpm initial climb rate at 100,000lb MTOW, same as the F-14D.  It'll reach 40,000ft in less than 3 minutes.  At a realistic combat weight with full internal fuel and weapons only, it'll "only" climb as fast as any existing fighter.

While this proposed long range interceptor technically has sufficient thrust to hit Mach 3 at altitude, we'll ignore such fanciful nonsense in favor of an airframe that still maneuvers like a world class air superiority fighter because we don't have to make the entire airframe out of refractory metals to cope with Mach 3 heating.

The F-14D carried 2,916 gallons of internal and external fuel.  In combat configuration, F-14D was limited to 6.5g, whereas the F-111F was limited to 7.33g.  Using modern high strength steels and composites, a modernized F-111 would be an 8g capable plane with full internal fuel and air-to-air weapons loadout.  Empty weight would be nearly identical to the F-14D.  A notional CF-111 Thrust-to-Weight Ratio (TWR) with 5,043 gallons of internal fuel vs max fuel, 8X internal Peregrine, and 500lbs for the crew would put it at 1.08:1, which is sufficient to accelerate in a vertical climb after takeoff.

This notional CF-111 would be equipped with 2X F-135 engines, regular ejection seats for the crew vs the historical crew escape pod, and 8X Peregrines in the internal weapons bay.  The wing and fuselage skins would be CFRP, same as all other modern fighters.  This puts empty weight at the same as the F-14D Tomcat.

Empty Weight TWR Chart
CF-111: 1.97:1
Typhoon: 1.67:1
F-15EX (no CFTs): 1.66:1
F-22A: 1.62:1
Su-57: 1.57:1
Rafale-C: 1.57:1
Su-35S: 1.53:1
F-35A: 1.47:1
Gripen-E: 0.94-1:1

CF-111 combines "all the thrust" with "all the fuel", because you're not going anywhere without fuel.  It beats every modern and historical tactical fighter in existence at the TWR game by a considerable margin.

Did I mention that the CF-111's nose would have more space for a larger AESA radar array than any other tactical fighter?

The APG-77 X-band radar supposedly has a detection range of about 510km against a Tu-95, so a 50% larger and more modern / powerful array ought to be able to detect any Russian bomber that the radar has line-of-sight to.

However, more modern fighter jet radars like the APG-81 and APG-85 trade some detection range in favor of image detail:

UC Berkeley - Accelerating Ukraine Intelligence Analysis with Computer Vision on Synthetic Aperture Radar Imagery

Imagine having a fighter jet radar capable of providing very high resolution video imagery of inbound enemy aircraft, so that your interceptor pilot knows exactly what kind of aircraft he's shooting at, rather than simply seeing a "blip" on his screen.

F-22 pilots still see "blips" on their radar, with some limited imaging capability against ground targets, whereas F-35 pilots see this on their radar:

The F-22 pilot can technically "see" at greater distances because its radar operates in a lower frequency band, but has only limited information about what the radar is actually "looking at".

The F-35 pilot can "see" an image-correlated overlay of the combination of their imaging radar with IR and UV.  It's a black-and-white motion picture of threats, as-if the pilot has "eyes" in the X-band, IR band, and UV band, all at the same time.  The computers backing these sensors also automatically classify imagery targets as potential threats vs friendlies.  A Block IV F-35 pilot will "see" an even higher resolution correlated sensor imagery overlay.  When APG-85 rolls in, they will see very high-definition / very high-frame rate correlated sensor imagery.  This data can then be "shared" with friendly air defense assets, so that the platform which detects the target doesn't also have to fire at the target.  This capability is useful when your jet is out of missiles, but your wingman or a nearby AEGIS-equipped ship is not.

Knowing exactly what your sensors have detected is very important, because it tells you whether or not you're about to shoot down a Tu-160 vs an Airbus passenger jet.

This proposal is all the thrust that a pair of the most powerful fighter jet engines in the world can provide, plus more internal fuel to keep them running than any other tactical fighter in existence, plus more radar imaging detail than anything the Russians or Chinese have in a combat jet.  That seems like a better than average proposition for finding and shooting down enemy bombers.

The downside, of course, will be the operating cost.  Big fancy fighter jets cost big money, so there will be fewer of them.