Nuclear airliners

RobertDyck · 2012-06-17 18:17:08

I think the time has come. Cost of air fare is going up, the main reason is rising cost of fuel. Cost to fly into my city, Winnipeg just north of North Dakota, is significantly higher than domestic flights within the US. Winnipeg used to be THE destination for conventions, it's the centre of the continent. But rising air fare has driven conventions away. I mentioned this to a college here in Winnipeg, and mentioned not only airport fees but the fuel surcharge. I feel any surcharge for fuel is unwarranted, that's a basic cost of airline operations so how can that add an additional fee? But they are. My college blames the cost difference on airport fees. He pointed out the US federal government pays for airports, but they'll have to start charging airlines like airports do in Canada. So his claim is air fare will rise in the US. Has this gotten to the point where people will accept an alternative?

In the 1950s the US air force worked on a nuclear jet engine for a bomber. The B-36 was the first big intercontinental bomber, predecessor to the B-52. The B-36 was intended to use nuclear jet engines, and able to circle near Russia for months. The only limit would be food and water for the crew. However, their design was an overly complicated thing with multiple heat exchangers, and radiation shielding was so good back then. They found sufficient shielding to protect the crew was so heavy the plane couldn't lift off. They did build a prototype, called the B-36N. Yes, there will be people who will argue the B-36 did go into service, but with conventional engines instead. There will also be people who point out the B-36N was only a prototype, but if you read documents about that plane's development, it was originally intended to have nuclear engines; it was changed to conventional engines only after they failed to get the nuclear ones to work.

The air force also developed a cruise missile, able to use a radar mapping terrain hugging autopilot. I thought cruise missiles were developed in the late 1970s, it was a shock to learn the air force worked on this in the 1950s. But more relevant to this discussion, the engine for "Project Pluto" was an unshielded nuclear reactor, configured as a ram jet. They got it to work, built a prototype. This unshielded reactor spewed its nuclear waste, technically called fission fragments, with its exhaust. While the reactor for the B-36 contained its waste, the missile known as "Project Pluto" didn't. They intended to air launch the missile from a B-52 over the ocean where nuclear waste wouldn't matter. It was to drop big nuclear bombs on Russian cities, so they saw any nuclear waste they spewed on Russia as a bonus. In fact, after the missile dropped its last bomb it would fly a figure 8 over another Russian city; they called this turning a peacetime liability into a wartime asset. The missile never went into production, but from my perspective the important thing was all that work on the nuclear jet engine.

So this brings me back to the point of this discussion. Several engineers have said that with today's technology, we could get a nuclear jet engine to work. The plane would be safe, and it would fly. Fuel would have to be highly enriched uranium. Plutonium is a richer fuel than uranium, but while uranium oxide is chemically not any more toxic than rust, plutonium is so poisonous that if a piece the size of a grain of sand got into a cut in your skin, you would be dead. The biggest danger from uranium is radiation, and that's very mild compared to radiation from nuclear waste. The primary danger would be to contain waste. Americium is also a rich nuclear fuel, but it's very expensive and doesn't occur in nature, it can only be made in a reactor from uranium. Because of cost, Americium isn't practical either.

A plane crash with nuclear jet engines wouldn't be any more dangerous than any other plane crash. So properly designed, safety isn't an issue.

The problem is public image. This same college immediately argued that you wouldn't want an airliner crashing out of the sky onto your house. Um, what!? This demonstrates the problem. Hollywood has always equated nuclear power with accidents. This was the same with robots in the 1950s. When an American engineer invented the first industrial robot, Americans would not accept it. They equated the word "robot" with Hollywood movies that always portrayed robots on a murderous rampage. Patents for the Unimate robot were files in 1954, granted in 1961. At first only Japanese car manufacturers would use it because they didn't have the Hollywood culture. When factory robots proved reliable and cost effective, they slowly grew around the world. Today Hollywood equates nuclear power with Chernobyl and Fukushima, and various disaster movies. Why let a little thing like reality interfere with movie mythology?

But air fares will rise much farther. Is now the time to move to nuclear aircraft? A nuclear jet airliner would be fuelled by nothing but uranium and air.

louis · 2012-06-18 06:30:40

RobertDyck wrote:

I think the time has come. Cost of air fare is going up, the main reason is rising cost of fuel. Cost to fly into my city, Winnipeg just north of North Dakota, is significantly higher than domestic flights within the US. Winnipeg used to be THE destination for conventions, it's the centre of the continent. But rising air fare has driven conventions away. I mentioned this to a college here in Winnipeg, and mentioned not only airport fees but the fuel surcharge. I feel any surcharge for fuel is unwarranted, that's a basic cost of airline operations so how can that add an additional fee? But they are. My college blames the cost difference on airport fees. He pointed out the US federal government pays for airports, but they'll have to start charging airlines like airports do in Canada. So his claim is air fare will rise in the US. Has this gotten to the point where people will accept an alternative?
In the 1950s the US air force worked on a nuclear jet engine for a bomber. The B-36 was the first big intercontinental bomber, predecessor to the B-52. The B-36 was intended to use nuclear jet engines, and able to circle near Russia for months. The only limit would be food and water for the crew. However, their design was an overly complicated thing with multiple heat exchangers, and radiation shielding was so good back then. They found sufficient shielding to protect the crew was so heavy the plane couldn't lift off. They did build a prototype, called the B-36N. Yes, there will be people who will argue the B-36 did go into service, but with conventional engines instead. There will also be people who point out the B-36N was only a prototype, but if you read documents about that plane's development, it was originally intended to have nuclear engines; it was changed to conventional engines only after they failed to get the nuclear ones to work.
The air force also developed a cruise missile, able to use a radar mapping terrain hugging autopilot. I thought cruise missiles were developed in the late 1970s, it was a shock to learn the air force worked on this in the 1950s. But more relevant to this discussion, the engine for "Project Pluto" was an unshielded nuclear reactor, configured as a ram jet. They got it to work, built a prototype. This unshielded reactor spewed its nuclear waste, technically called fission fragments, with its exhaust. While the reactor for the B-36 contained its waste, the missile known as "Project Pluto" didn't. They intended to air launch the missile from a B-52 over the ocean where nuclear waste wouldn't matter. It was to drop big nuclear bombs on Russian cities, so they saw any nuclear waste they spewed on Russia as a bonus. In fact, after the missile dropped its last bomb it would fly a figure 8 over another Russian city; they called this turning a peacetime liability into a wartime asset. The missile never went into production, but from my perspective the important thing was all that work on the nuclear jet engine.
So this brings me back to the point of this discussion. Several engineers have said that with today's technology, we could get a nuclear jet engine to work. The plane would be safe, and it would fly. Fuel would have to be highly enriched uranium. Plutonium is a richer fuel than uranium, but while uranium oxide is chemically not any more toxic than rust, plutonium is so poisonous that if a piece the size of a grain of sand got into a cut in your skin, you would be dead. The biggest danger from uranium is radiation, and that's very mild compared to radiation from nuclear waste. The primary danger would be to contain waste. Americium is also a rich nuclear fuel, but it's very expensive and doesn't occur in nature, it can only be made in a reactor from uranium. Because of cost, Americium isn't practical either.
A plane crash with nuclear jet engines wouldn't be any more dangerous than any other plane crash. So properly designed, safety isn't an issue.
The problem is public image. This same college immediately argued that you wouldn't want an airliner crashing out of the sky onto your house. Um, what!? This demonstrates the problem. Hollywood has always equated nuclear power with accidents. This was the same with robots in the 1950s. When an American engineer invented the first industrial robot, Americans would not accept it. They equated the word "robot" with Hollywood movies that always portrayed robots on a murderous rampage. Patents for the Unimate robot were files in 1954, granted in 1961. At first only Japanese car manufacturers would use it because they didn't have the Hollywood culture. When factory robots proved reliable and cost effective, they slowly grew around the world. Today Hollywood equates nuclear power with Chernobyl and Fukushima, and various disaster movies. Why let a little thing like reality interfere with movie mythology?
But air fares will rise much farther. Is now the time to move to nuclear aircraft? A nuclear jet airliner would be fuelled by nothing but uranium and air.

The V1 of WW2 was a cruise missile - it just wasn't referred to as such. The Russians also had robot tanks in WW2. Things were pretty advanced then.

I recall an interesting debate before the Great Crash about the earliest date at which humanity could have successfully got into orbit. It might easily have been the 1930s.

Terraformer · 2012-06-18 06:44:54

Oh, I think it was much earlier than that. 1910 at the latest.

Anyway, the trouble with nuclear airliners is that the shielding weight is going to be prohibitive, and if you solves that using shadow shields and other such fancy tricks, you're not going to be able to land the craft without powering down the reactor. Which is going to be expensive.

You could, of course, keep the craft in the sky and ferry passengers to it. Or, even better, you could use nuclear power on the ground to synthesise fuel, and use that...

RobertDyck · 2012-06-18 12:48:33

An aeronautical engineer who told me about this, it's not originally my idea, Janyce Wynter raised the idea. She suggested engines on the wing tips, and the airliner would park at a safeing area where the engines would be removed and stored in pair of pits. Only once the engines are removed would the aircraft be towed to the terminal building for passengers to disembark. When the plane has a new set of passengers and ready to take off for its next flight, it would return to the safeing area where the engines would be put back on. Then it would taxi directly to the runway. I see several problems with that: if engines can be removed easily, there's a danger they could fall off in flight. Second, logistics of storing engines for every aircraft at the airport. I don't know about your airport, but the airport for my city is very busy. It used to be the hub airport for all Canadian airlines, traffic reduced considerably since hub activity was moved to Toronto, but it's still very busy. In fact they just built a new terminal building to handle increased aircraft traffic.

Radiation reflectors help a lot! They reflect neutron radiation back into the reactor core. This sustains a reaction with a much smaller quantity of fissionable reactor fuel (uranium), but it also keeps most of the radiation in. Don't expect the same radiation issues as the 1950s; nuclear engineers can do a lot better job now.

The other issue was the B-36N used a single big reactor in the body of the aircraft. It was designed with 4 "engines" that had a traditional turbojet compressor and turbine, but rather than a jet fuel combustion chamber directly between them it routed air through ducts into the aircraft fuselage where it passed through a heat exchanger from the reactor. To make it worse, a later design used a second heat exchanger: liquid from the reactor passed to an external heat exchanger, which then heated air ducted from the engines. I would call this a "Rube Goldberg" design, overly complicated. Project Pluto had the reactor directly heat air through the engine. Again the problems with Project Pluto were 2 fold: it used plutonium, and was completely unshielded.

I would have heat from the reactor conduct directly through a metal heat sink. Coat the heat sink with the same glaze as black tiles on the space shuttle, they were designed to radiate heat through hypersonic air. When the shuttle first entered the atmosphere, it was very thin air but the shuttle entered at mach 25. I think shuttle heat shield technology could be used for heat sink fins for this engine. And build the reactor very small, with one reactor within each engine. No ducting. Keep it simple to keep it small and light-weight. In fact, you could use a turbofan engine design instead of turbojet; that design is optimal for the speeds that modern airliners fly. That's why they use them now.

Although I believe airliners can be built with sufficient shielding on the engines, one option is to build an airport terminal with radiation shielding in the building. That is, where an aircraft pulls up to the building with a passenger "bridge", shielding between the aircraft and the building. And additional enclosures that can rise out of the tarmac to surround the engines. There is already the passenger bridge, and currently underground jet fuel tanks with fuel connections near each aircraft parking spot; this would just be different airport infrastructure.

But again, many members of the public are currently afraid of the word "nuclear". It's as if the moment they hear that word they had to self-flagellate with holly branches. This fear comes from the same Hollywood movies that depict cars exploding with any accident. I saw an episode of Mythbusters in which they tested this myth. They couldn't get a gas tank to explode; it takes a perfect mixture of fuel and air, with the gas atomized to explode. A carburetor or fuel injector does this, but a gas tank just burns. Fire is dangerous, but it doesn't explode. However, Hollywood has shown cars exploding so often that when I explain this, most people try to tell me I'm wrong. Hollywood has conditioned these same people to think "nuclear" means danger.

Last edited by RobertDyck (2012-06-19 00:08:15)

Adaptation · 2012-06-18 23:27:15

Gas tanks can and do explode on occasion, I have only heard of it happening after the car was on fire for a while.

I'm fine with military nuclear plains, I believe the assertions that the reactors can be made crash proof.

The trend in commercial aviation is small planes with frequent flights to more destinations. And I don't like the idea of thousands of passenger planes flying around the world with enriched uranium. It's a potent substance in a bomb dirty or otherwise and I would consider it too big of a security risk. Perhaps it would be acceptable for a hand full of very large trans ocean services with limited destinations.

I think the future is electric for short flights liquid natural gas for medium ones and the same old jp1 for distance flights.

On the other hand you come up with a cute little thorium reactor and we'll be in business.

Terraformer · 2012-06-19 02:56:55

What about increasing the number of commercial nuclear ships? You could spin it as being more "green", reducing the "carbon emissions" fron shipping, while at the same time allowing cheap shipping to remain viable. We already know how to do nuclear with ships - a lot of navies do it regularly. Perhaps, with nuclear power plus drag reduction, we'll be able to increase the speed of the craft much more, so that it'll be a few days across the Atlantic.... Depending on the ticket price, that might be good enough for passengers...

Rune · 2012-06-19 09:36:45

As Terraformer pointed out, leave the nuclear plants on the ground and make jet fuel with them (Hydrogen or methane, or longer chain hydrocarbon, whatever works cheaper). Safe nuclear reactors take lots of containment, in case everything else fails and you have to just seal the bad stuff away, which is why maritime operation is as small as I would make them. And any open-cycle reactor like you suggest, no matter how good the fuel cladding is, is going to spew out the back some amount of activated materials direct form the core. Activated materials is, as a general rule, nasty stuff that greenies are very right to not want spewed all over the place.

Hell, even it containment was perfect, partial shielding (shadow shields) means you will irradiate and therefore activate any particle suitable for activation floating in the atmosphere. However small the contamination is, multiply by the amount of flights on commercial aviation nowadays and you will get a very unacceptable amount of radiological waste floating around major cities. Not to mention the size and cost of the nuclear industry to provide very-high-grade cores for such a big number of aircrafts. Nuclear material security is also a concept killer: you may leave low-grade nuclear fuel in the hand of civilians if you control very harshly all the fuel processing facilities (there are some clever fuel cycles that don't leave nasty stuff in the plants), but you won't give them very high-grade fuel than can be used for bombs without further refining, period.

Rune. Project Pluto was more scary without a warhead, that should have settled the question already.

RobertDyck · 2012-06-19 11:40:58

Rune: Thank you for responding. I didn't say "open cycle". I'm trying not to jump on every comment, but I didn't say "open cycle". NASA developed effective containment for their NERVA rocket. They designed the rocket in the 1960s and early 1970s, by 1972 all development and testing was complete, all that was left was to test it in space. They used uranium that was over 99% enriched. That means over 99% U-235, U-233, and U-232; less than 1% was U-238. But their design mixed the uranium with ceramic, then baked into a hard fuel element. Think of it like raisin bread, with raisins representing uranium and bread the ceramic. Even if a fuel element breaks in two, you just expose a new face of the "bread", the uranium doesn't spill out. The ceramic will contain any fission fragments, which is the technical name for the nuclear waste that is formed after uranium atoms are split.

Years ago on this website I went through every isotope of every gas in Earth's air, and described what would happen to it when exposed to neutron radiation. The result was not dangerous; in fact the tiny quantity of heavy water in humidity in the air would become tritium. That is deuterium would become tritium. That's all, and that would decompose to helium-3 releasing beta radiation. Beta radiation is so weak it's stopped by human skin, it's only dangerous if you drink it. The half life of tritium is 12.33 years, but the quantity is so low it's less dangerous than car exhaust. The trick is don't let anything solid get irradiated; solid stuff is what becomes radioactive. So the engine requires shielding to prevent irradiating the terminal building or tarmac, but not air passing through the engine.

However, the concern with placing highly enriched uranium in the hands of civilians is legitimate.

Rune · 2012-06-19 14:53:53

That is all fine and good, and in fact I knew it or most of it, but when you have the fuel elements in direct contact with the working fluid, that in my book is an open system. Excuse me for putting words in your mouth, but that is my read of your posts ^^'. And yes, NERVA fuel claddings were awesome. Some even more awesome can be built today. None of them will be perfect, and the core elements will have a measurable rate of degradation and corrosion, especially if they work on atmospheric air instead of chemically pure hydrogen. And that is why engineers looking into the problem of flying bombers with nuclear engines bothered with heat exchangers and secondary loops, so they could work with closed systems and contain 100% of the reaction products. Because 99.999% fuel containment is not enough, when you are going to have tens of thousands of birds flying around cities. A few rocket launches, maybe you can get away with it, but not civil aviation.

As an incidental note, I must say at this point that Reaction Engines' 400MW precooler (something like 500kgs in weight, they one they developed for Skylon, you must have heard of it) would work wonders on the system weight of the old nuclear bombers idea with a primary coolant loop running conventional airbreathing engines. Who knows, that technology might even make the whole thing light enough to fly, though I doubt that could ever be economically competitive with, say, standard jets that let their nuclear fuel factories on land to run on chemical batteries (AKA fuel). But perhaps if you wanted super-endurance...

As to irradiation, have a look at the shit suspended in your backyard's air. I myself live in Madrid, Spain, so I can assure you I breath a very unhealthy dose of heavy suspended particles every day. Quite a lot of other nasty stuff, too. Of course light elements are not dangerous after irradiated. In an ideal world, yes, radiation cannot make radioactive air. In this one, nuclear planes will never fly because of it.

And last but not least to the proliferation issue... let me clarify: no further NUCLEAR refinement or enrichment. Chemical treatment alone will separate the uranium from the cladding and the ceramic matrix very quickly, and almost anyone could do it, it's the easy part in fuel processing. The hard thing is to get enough percentage of the desired isotopes among the uranium you refine (or plutonium), which is what the compact engines need. And what Iran is getting scolded for trying, too.

Rune. And I'm as pro-nuke as you can find them, and seriously, I don't see it.

RobertDyck · 2012-06-19 17:41:10

I did say "metal heat sink". That means enclosing the reactor core and its fuel elements. But instead of liquid to conduct heat from the core to a heat exchanger, the metal heat sink would be in direct contact with the core. That means the core and its fuel would be completely contained within a metal shell, so you do have containment. The metal would use the same (or similar) thermal compound as Personal Computers use to bond their CPU to a metal heat sink. So envision thermal grease bonding the fuel elements to a heat sink with fins, or metal heat pipe leading to a heat sink with fins. The fins coated in the same material as the black tiles on the space shuttle.

I just saw a documentary on the factory that builds Bentley Mulsanne cars. They test one in 1,000 engines to max rev's. The exhaust manifold leading to the turbocharger reached 1,000°C, it was glowing red hot. If a car can do that, then the heat sink of a jet engine can do at least as well. Black tiles on the shuttle were rated for up to 2,300°F (1,260°C).

Glandu · 2012-06-20 02:21:30

Incidentally, The reason why Europe & coastal China were ahead of time before fossil fuels did appear is strongly related : in those places, distances are short, & you can go here or there without being blocked too much by the landscape/climate. Winnipeg can only thrive through intense energy use for transport & so.

That being said, I have another problem with nukes : amount of uranium/thorium/whateverium is not unlimited. Such a solution(nuclear on plane or building energy on ground) cannot work for centuries.

RobertDyck · 2012-06-20 03:59:46

Glandu: I have an opportunity to host a Mars Society convention here. The founder of the local science fiction convention, Keycon, wants to organize it. He was also one of the organizers for World-Con in Calgary. He offered to bring the entire crew who run Keycon every year, a convention the same size as the Mars Society. You coming?

Glandu · 2012-06-20 07:52:35

Well, thanks, but from Paris, France, it's rather far, I fear. I first shall join the french branch of Mars society.

RobertDyck · 2012-06-20 10:33:34

And my fear is most Americans would find air fare to Winnipeg too much. And after 9/11 Americans must have a passport to get back; most don't have one. My point is the status-quo isn't acceptable.

louis · 2012-06-20 14:41:38

Terraformer wrote:

What about increasing the number of commercial nuclear ships? You could spin it as being more "green", reducing the "carbon emissions" fron shipping, while at the same time allowing cheap shipping to remain viable. We already know how to do nuclear with ships - a lot of navies do it regularly. Perhaps, with nuclear power plus drag reduction, we'll be able to increase the speed of the craft much more, so that it'll be a few days across the Atlantic.... Depending on the ticket price, that might be good enough for passengers...

What about green energy ships using a combination of solar power, wind turbine power, aerial sail and wave power - all four have been trialled at sea and found feasible. Put the four energy sources together and you probably have a working system.

RobertDyck · 2012-06-21 23:29:15

So you guys want to go green. That's another discussion. Yes, I believe in green technology, and could list what I want to build into a house. However, none are practical for an airplane.

Ships cannot use wave power, they float so wave power is not compatible. The most efficient means of using wind to move a ship is sail, and wind turbines are not compatible with sail. So for a ship that leaves a combination of sail and solar. You could use photovoltaic for electric power generation, and sail to move the ship. Tall sailing ships do not move as fast as deisel, and the ship is at the mercy of weather (wind).

louis · 2012-06-22 02:03:35

RobertDyck wrote:

So you guys want to go green. That's another discussion. Yes, I believe in green technology, and could list what I want to build into a house. However, none are practical for an airplane.
Ships cannot use wave power, they float so wave power is not compatible. The most efficient means of using wind to move a ship is sail, and wind turbines are not compatible with sail. So for a ship that leaves a combination of sail and solar. You could use photovoltaic for electric power generation, and sail to move the ship. Tall sailing ships do not move as fast as deisel, and the ship is at the mercy of weather (wind).

Wave power for use by sea vessels is certainly feasible. See this article:

http://inhabitat.com/transportation-tue … ered-boat/

I don't think we are talking about tall sailing ships - more likely fixed sails that extend either side of the ship AND aerial sails (like paragliding parachutes). Both have been trialled.

Speculatively, one might also run out a huge solar PV surface on floats behind the ship (almost like a trawler net) that would generate huge amounts of PV electricity.

Obviously none of this is cost effective yet, but I think it could be in the same way wind turbines are now cost-effective over a period of 5-7 years. Toyota announced last year they had developed a new cheap battery that is about 5 times more efficient than current lithium batteries. That could make a huge difference.

As for aircraft, the most obvious power source is green bio fuels. Virgin Atlantic are already moving over to green bio fuels. Longer term I think cold fusion may have the right mix of cost-effective power and energy density, but we await developments on that front.

GW Johnson · 2012-06-22 18:05:51

Re: nuke B-36

It was the NB-36, not B-36N. This was a variant of an original 6-engine piston-prop design, not the intended design-that-didn't-work. There was a nuke turbojet engine design that they wanted to fly in it, but never did. They did fly a simple reactor and generated heat in flight. No real power output in usable form, though. That reactor flew inside a containment vessel tested to 500 mph impact against solid rock, on the rocket sled track at Holloman AFB, NM. The all-jet version of the B-36 came later, as the YB-60 8-engine prototype built and flown for the competition that resulted in the B-52, which in turn originally on paper was a turboprop resembling the Tupolev "Bear".

B-36 originally flew about 1945 or 1946 as a prototype with a single-tire main gear. Then B-36, B-36B, and B-36C flew configured with a 4-tire main gear truck (for safety's sake, since a blowout on the single tire design meant loss of aircraft and crew). All of these variants were 6 engine piston-prop, using the R-4360 4-row 28 cylinder radial engines of around 4000 SHP. From B-36D-on it was a 10-engine airplane: the same 6 piston-prop pushers, plus 4 early turbojets in two twin-engine pods, each out near the wingtip. B-36 is the ship with passages inside the wings out to the engines for in-flight maintenance.

I do not know which model of the B-36 was converted to NB-36 for the nuke flight tests. But I know they never actually flew the nuke turbojet. I don't know how much testing the nuke turbojet got on the ground, if any.

Re: nuke ramjet cruise missile

The Project Pluto cruise missile was a Mach 3 cruise, but very low altitude, ramjet. LTV Aerospace was airframe prime plus the inlet and nozzle guy, and AEC was to supply the reactor core. My father remembers this project, he was there when they did it, and told me what he knew. He didn't work on that one, though. Too busy designing the F-8 Crusader, among many other things. The shock wave alone was lethal to those on the ground, much less the spewed radiation. It would have killed more folks on the ground flying around, than with any warhead it could carry, and it carried a megaton-range fusion nuke.

This Pluto nuke ramjet thing got direct-connect tested on the ground at the Jackass Flats facility in Nevada on the old nuclear test site, adjacent to the nuclear rocket test facility. Some, but not all, of that gear is still out there, from both projects. Unlike NERVA, the Pluto guys were operating their reactor at a 10 deg F (5 deg C) margin above meltpoint for the reactor core supports. They had really bad erosion problems, never solved, unlike NERVA.

Re: earlier cruise missiles and jet aircraft

The V-1 Buzz Bomb of WW2 is often called the first cruise missile, but it was not. That distinction goes to a gyro-controlled pilotless biplane in WW1, which was Oliver Sperry's very first working automatic flight control and guidance system.

Gunther Diedrich at Argus Engine Works corrected some of the defects in Paul Schmidt's pulsejet tube to build the valved engine for that missile. He gave up work on a promising valveless pulsejet design to do that work for the Luftwaffe. The valve life averaged 45 minutes. Average flight time from France to London was 43 minutes. BTW, Luftwaffe test pilot Hanna Reisch (yep, a female!) was the first pilot to survive flight test flying the V-1. 6 died before her. She only died a few years ago. (I probably misspelled her name.)

Neither was the first jet engine to be flown a German turbojet in WW2. There was an Italian afterburning ducted fan that flew about 1939, but it was not the first, either. The very first jet powered flight took place in France in 1910 (yep, before WW1!!!), and it was accidental. Henri Coanda built two biplanes powered by an afterburning ducted fan, and accidentally took off and flew during a high speed taxi test. He crashed, but survived. The aircraft didn't. The surviving example still exists in a museum in France way outside Paris, BTW. It crashed because he had not yet trained himself to be a pilot.

We stand on the shoulders of the giants who preceded us. Sometimes it is really worthwhile to know who they were and what they did.

GW

GW Johnson · 2012-06-24 16:49:49

All that I said in post no. 18 being what it is, I think the sense of Robert Dyck in post no. 1 is correct. We need a cheaper way to fly, one that is more or less independent of oil prices. If that's some nuclear engine, then so be it.

I'm not sure how this might be done at less than transoceanic ranges. But crossing ocean basins is flying across a fair fraction of the Earth's circumference. Once you're in that ballpark, an old science fiction idea rears its head as the best way to do things. Why not fly ballistic outside the Earth's atmosphere? The old "antipodes rocket" idea of Robert Heinlein. Actually, it makes good sense.

Once the range to be covered approaches half the Earth's circumference, the cost of accelerating high supersonic-to-hypersonic out of the atmosphere approaches the cost of cruising high subsonic over the same range. The cost of cruising supersonic over that same kind of range will never be as low, in my opinion, because of supersonic drag levels and supersonic aeroheating levels.

For a long range mission across an ocean basin, consider what it takes to reach Mach 3 to 6 on a short transient (minutes). Then look at sustained Mach 2 to 3 cruise (hours) vs that ballistic ascent into space. While you're coasting in vacuum, you can cool off by radiation. There is no drag. But cruising in the atmosphere at Mach 2 to 3 is very hot, and is done at very high drag.

Honestly, I have never understood why anyone would want to cruise supersonic in the atmosphere, when coasting in vacuum is so much easier to do. But, that's just me.

GW

Last edited by GW Johnson (2012-06-24 16:55:16)

Glandu · 2012-06-25 02:39:50

GW Johnson wrote:

All that I said in post no. 18 being what it is, I think the sense of Robert Dyck in post no. 1 is correct. We need a cheaper way to fly, one that is more or less independent of oil prices. If that's some nuclear engine, then so be it.
(.../...)GW

IIRC, I read a french study about the 2000-2009 decade, summarizing the energy consuption of different transport modes per pessenger. It was like :

_Rail : 0.2
_Boat : 0.4
_Tyres : 2.2
_Air : 3.2

For anything not transoceanic, rail it the obvious choice. But Transatlantys is not for tomorrow(it was an advertisment joke promising a train tunnel between France & New York City).

I'm not sure coing nuclear would significantly reduce the energy cost of an airplane(in terms of joules, not in terms of $).

GW Johnson · 2012-06-25 13:25:48

The energy cost of nuclear vs chemical is a big unknown, since a practical nuclear aircraft engine is still unknown. But, depending upon the thermodynamic cycle efficiency, it could be energetically cheaper. This might be true of an in-atmosphere cruiser, or a skip-glide exoatmosheric design, or even the antipodal rocket. We don't know.

The money cost depends upon that and the relative operating costs, which can be quite different. If oil gets expensive enough, nuclear air travel and nuclear or sail surface boat travel start looking much more attractive. The flier is fast. The boat is slow. So what is the difference in time worth? There is no one answer to that question.

But if some kind of emergency happened such that we need fast oceanic travel in a craft as re-usable as an ordinary jet plane, I'd look first at a winged nuclear rocket airplane on the ballistic trajectory outside the atmosphere. I'd start with the old NERVA technology, and maybe upgrade it later with some sort of gas-core nuclear light bulb engine.

The same thing could be done with chemical, of course, if oil were not a problem. Turbojet to ramjet would work well, leaving the atmosphere at M3 to M6, depending upon the range to be crossed. If you have a rocket too, then you can pull the exit trajectory up to about 45 degrees, and really extend the range without any skip-gliding. Mixed propulsion really makes a lot of sense for a thing like that. Transpacific in maybe 2-4 hours.

Skip-glide would be a bit faster trip, but more wasteful of fuel with multiple high-speed burns on each skip.

GW

louis · 2012-06-25 14:56:36

Glandu wrote:

GW Johnson wrote:
All that I said in post no. 18 being what it is, I think the sense of Robert Dyck in post no. 1 is correct. We need a cheaper way to fly, one that is more or less independent of oil prices. If that's some nuclear engine, then so be it.
(.../...)GW
IIRC, I read a french study about the 2000-2009 decade, summarizing the energy consuption of different transport modes per pessenger. It was like :
_Rail : 0.2
_Boat : 0.4
_Tyres : 2.2
_Air : 3.2
For anything not transoceanic, rail it the obvious choice. But Transatlantys is not for tomorrow(it was an advertisment joke promising a train tunnel between France & New York City).
I'm not sure coing nuclear would significantly reduce the energy cost of an airplane(in terms of joules, not in terms of $).

Rail doesn't take you to your door. A car does. So does a bike. I wonder if the survey included the energy expenditure of getting to the rail station and hanging around waiting for trains?

Glandu · 2012-06-26 01:46:40

louis wrote:

Rail doesn't take you to your door. A car does. So does a bike. I wonder if the survey included the energy expenditure of getting to the rail station and hanging around waiting for trains?

Nope : it's energy per pessenger per kilometer(forgot the unit, just remembers the scale). With streetcars(i.e. american-style small scale tramways), though, you can go rather near home. If we don't find adequate replacement to petrol, public transit will have its importance improved - and cities will need to be more dense, more Washington DC than Calgary. Note though that for cities with heavy slopes, tyres are still useful - that's why inhabitants of San Francisco avoid the cable car & use trollebuses instead. Only tourists use cable car.

Nuclear planes might be useful for transatlantic transport, but won't for going from home to work.

louis · 2012-06-26 02:17:07

Glandu wrote:

louis wrote:
Rail doesn't take you to your door. A car does. So does a bike. I wonder if the survey included the energy expenditure of getting to the rail station and hanging around waiting for trains?
Nope : it's energy per pessenger per kilometer(forgot the unit, just remembers the scale). With streetcars(i.e. american-style small scale tramways), though, you can go rather near home. If we don't find adequate replacement to petrol, public transit will have its importance improved - and cities will need to be more dense, more Washington DC than Calgary. Note though that for cities with heavy slopes, tyres are still useful - that's why inhabitants of San Francisco avoid the cable car & use trollebuses instead. Only tourists use cable car.
Nuclear planes might be useful for transatlantic transport, but won't for going from home to work.

Of one thing I'm sure, we already have the answer to petrol for cars.

Utah University has already built electric roads which could be used to power electric vehicles through wireless charging. And of course the electricity for the vehicles can come from wind and solar (plus hydro, energy from waste etc) any time. Toyota has developed a new highly efficient battery which should be out in the next year or so which is a bit of a game changer - extending range at lower cost, which will also help greatly. The primary roads can have the wireless electric charging - for the rest of our journeys we can rely on the batteries which we either charging at home or whileon the primary roads.

Glandu · 2012-06-26 03:26:23

But you have the energy efficiency of a tyre vehicle, not from a rail vehicle. That's a 1-to-10 ratio.

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