Reaction Engines plan Mach 5 Airliner

What is? writes "A British company has designed an eco-friendly airliner that could make a trip from London to Sydney in under five hours. Reaction Engines has received funding from the European Space Agency to design the plane as part of the Long-Term Advanced Propulsion Concepts and Technologies project. The A2 airliner would be capable of carrying 300 passengers at speeds of up to Mach 5."

Easy choice

FTA:

Two major directions at conceptual and technological level are considered: ram-compression and active compression

Use ram-compression, we already have well-known solutions like Huffman and Lempel-Ziv.

Still it would make

for a nice crater.

Use Both Traditional and Ramjet

I do not know if you were joking but I think this is a hybrid style engine. I do not know a lot about this sort of stuff but the Wikipedia entry [wikipedia.org] provided this interesting point:

Behind the pre-cooler, the SABRE system consists of a number of different engine components, each tuned to a different portion of the flight. SABRE uses two "pure" rocket engines surrounded by a ring of smaller engines similar to ramjets.

It looks like this design is a combination of rocket engines and ramjets.

Re:Use Both Traditional and Ramjet

I can't believe the mods modded the grandparent "Informative" for that gag. What's the world coming to when Slashdot readers can't even recognize ZIP and BZ2 compression algorithms? :-/

It looks like this design is a combination of rocket engines and ramjets.

Yeah, it's a dual-mode engine. If you do a little research on them, you'll probably find that aerospace designers discounted such designs a long time ago. The problem they ran into was that rocket craft spend so little time in the atmosphere that the extra weight and complexity incurred through dual-mode operation ends up gaining very little over a BDB. (Big Dumb Booster)

The only time they really make sense is for nuclear engines. In the case of nuclear, you can use anything that can be heated and exhausted as fuel. This leads to three options that can be used to power a Nuclear Thermal Rocket:

1. Pass air through the reactor, heating it up and using it as rocket exhaust. This is relatively low thrust and would only be useful in combination with another booster or to maintain velocity in the atmosphere.

2. Pass air through the reactor, heating it up and using it as rocket exhaust. As the air exits the engine, add hydrogen fuel for a second reaction. This greatly improves thrust at the cost of fuel efficiency. Perfect for initial takeoff.

3. Pass a stored, lightweight material like hydrogen through the reactor, heating it up and using it as rocket exhaust. Thrust is good in this mode, but not great. Depending on the design of the craft, this could be used 100% of the time or while in space.

Creating such "Tri-Mode" engines is reasonably straightforward and has been done. (e.g. The Triton Nuclear Engine [nuclearspace.com].) I'll leave it as an exercise to the reader to understand why they're not already in use.

Re:Use Both Traditional and Ramjet

I'd wager, based on the "programmer" job candidates I've interviewed over the years, that the average /.er couldn't bubble sort themselves out of a paper bag.

Over some 20 years, I met one, count 'em one candidate who correctly coded a Shell sort without blinking in an interview.

My question is basic, "Code a routine to sort a set of objects of any type of your chosing, based on a means of ordering them (comparison function). Use the language of your choice. The routine should be correct, and you be able to describe it's worst-case performance in O(n) notation. It need not be the most effective way of doing it."

Unfortunately, the candidate above made the fatal interview mistake of expounding on his personal school project "FTP server with dynamically loadable file-type handlers, based on requested file extensions" (to dynamically generate content based on extension), as a "servlet-supporting FTP server" to a different interviewer -- with a marketing backround -- who, for some reason, was trying to conduct a technical interview, when he should have been getting a feel for the candidates business sense.

This other interviewer dismissed the candidate as a fraud because "everyone knows" that web servers use servlets and ftp servers "don't".

Sadly, we had a policy where every interviewer had to "green light" a candidate for them to be hired.

And people wonder why so much software is crap.

CG is Cheap

I've seen more computer generated designs for supersonic passenger aircraft than I can count.

Is this going to be a real commercial jet, or just another cock tease?

Nothing New

Lots of people have websites with cool drawings [google.com] of fast planes. I scanned the material on their site and didn't see anything concerning a flux capacitor, so my cynicism is slightly abated.

Oh, won't somebody please think of the math

I'd love to see how they can make an "eco-friendly" airliner that goes Mach 5. There are some really basic laws of aero and thermo dynamics that put the kibosh on most of these schemes. Look at the Concorde, XB-70, SR-71, for examples of how difficult and expensive it is to design, test, and operate anything going Mach 2 to Mach 3.3. And the problems just go up from there, often by squares and cubes.

Re:Oh, won't somebody please think of the math

If I remember correctly, math as well as NIMBY's contributed to the Concorde's poor effect on the environment. People weren't too keen on having sonic booms regularly occur over their neighborhoods as widespread commercial adoption occured, so Concorde flights had to take care to avoid disturbing high population areas. Any gains that this plan makes in engine efficiency will probably be offset by having to reconfigure flight plans from the most efficient to the least bothersome for residents.

I just don't think there is a commercial viability for supersonic flight. The need to decrease flight times from 20 hours to 5 hours is just not enough of an incentive to cover all the associated investments and pitfalls of implementation.

Re:Oh, won't somebody please think of the math

Right. We'll just step up production from our vast hydrogen mining industry. Oh, wait. We don't have anything like that. Mostly we get hydrogen from water, which often means running an electric current through it. Since US enviros oppose nuclear, won't allow new dams for hydro because it upsets the fish, and have fought new natural gas exploration for fear it will damage pristine ecosystems, that probably means that coal is being burned to produce that electricity. Nice, clean, eco-friendly coal. In fact, because of losses creating the hydrogen and then burning it in the engine, it's less efficient than the coal plant, so you have to burn more coal for the energy used.

Hydrogen is eco-friendly *at the point of use*, but unless someone can magically cause it to appear its production isn't environmentally sound at all. You just hide the costs and emissions somewhere that the public hopefully won't notice it. (Same with electric cars. Using electric doesn't pollute. Making it certainly does. Anyone telling you different wants your money or your vote.)

Re:Oh, won't somebody please think of the math

Hydrogen is normally produced [wikipedia.org] via steam reforming and related processes (water gas shift reaction, coal gassification, etc), not electrolysis. That is, the hydrogen and the energy to produce it both come from fossil fuels (mostly natural gas, but oil and coal can both be used -- though in the case of coal all the hydrogen is coming from the water).

And actually, there is currently a *huge* hydrogen production industry. It's just mostly used on site at large plants rather than shipped to consumers as energy storage. Ammonium nitrate fertilizer is a *gigantic* market, and it's made by combining atmospheric nitrogen and hydrogen into ammonia, and then converting some of that ammonia into nitric acid before combining the two to form AN.

The availability of hydrogen is actually only a minor detail in this design. The price and the awkwardness of handling the ultra light weight ultra cold liquid are much more relevant.

Re:Oh, won't somebody please think of the math

It might be splitting hairs, but most of our hydrogen comes from steam reformation of methane, not from electrolysis of water.

Your point about electric cars I don't really get. Sure you have a longer tailpipe with an electric car, but if your thermal efficiency and CO2 or whatever pollutant you care about per mile is less, you are still winning. There are other technical challenges for electric cars, and a lot of people might not see that you have to look at the bigger picture, but even when you do EVs look pretty good.

reference on EVs here [evworld.com]

and yes I recognize that is an EV advocacy site, but their point is correct. IC engines have a thermal efficiency of about 15% or less. It's not hard to beat that with a stationary plant.

Now, about the present article - I'd like to see some analyses that say that you can actually fly a supersonic plane a good distance on hydrogen, and how the hell you think you can make that economical.

Mach 5

Funny how they write about a Mach 5 airliner precisely when Slashdot crawls down to something like Mach 5e-55.

Let me guess..

..they're buying the old Concorde airframes and launching them from the US Navy's new railgun?

300 passengers?

Does that include the monkey and toddler hiding in the trunk?

noise & fuel costs

First, those look like low-bypass engines (yes, I know they are "normal" jet engines), which means very high exhaust velocities. The small wing also means high wing loading and high takeoff velocities. Those two facts seem to suggest a very loud plane which might run afoul of EU regs.

Second, I can't help but think that fuel costs will kill this idea. GIven rising energy prices (and no large-scale miracle hydrogen factories on the horizon), the fuel costs will tend to track oil and nat gas prices. Even "free" wind/solar power won't help because a hydrogen factory would need to pay a competitive price for energy, which will be tied to the rising cost of fossil fuels and the rising global demand for energy.

That said, I'd love to fly in this thing even though the artists sketch shows a lack of windows due to heat issues :(

Re:

GIven rising energy prices (and no large-scale miracle hydrogen factories on the horizon), the fuel costs will tend to track oil and nat gas prices.

Hydrogen sucks for aircraft. The energy density is better than gasoline, sure, but the mass density is ho

Noise and price issues?

The original SST project (US) never got off the ground, and the Concorde was nothing more than a status symbol for those who could afford the ungodly high ticket price for the NYC-London (or Paris) run. The Soviet version (TU-144?) only had a limited set of routes as well, and Aeroflot killed it off (IIRC) about the same time the USSR crashed.

The issues boiled down to two things that no amount of tech could alleviate: Noise issues (property owners near the airports got highly vocal about having to replace cracked windows from the occasional sonic booms), and price ($25k 1st class from NYC to Paris? And now you get to suffer the indignities of airport security too? Sounds like a masochist's dream come true...)

Unless/until they solve at least those two issues (in spite of public pronouncement, it doesn't look like they have IMHO - yet), they're going to have a hard time with it's initial public image, fuel economy be damned.

Sure the economics of volume may drop the price, and sure the noise problem can be solved through strict pilot discipline (e.g. no cracking the sound barrier until you're x miles away and at y altitude), but that won't change public perception that Concorde planted firmly in the public mind back during the 1970's).

OTOH, the tech is cool, and I can see a very solid use for it for trans-pacific passengers... Seattle to Tokyo in 3 hours instead of 12? Frickin' awesome...

/P

Re:Noise and price issues?

Price will come down if fuel economy is reasonable and there are enough airplanes and flights to amortize development costs over. My impression (I've been following them for a while, and talked to people who should know) is that they're technically competent, and if they say they can get the price down, they can -- but that they're being overly optimistic about the market. Of course, if the government is paying for a low of the development, that helps a lot.

Noise is actually quite amenable to a technical solution. The first problem (noise near the airport) is a result of high-power, high exhaust velocity engines, combined with a need to get up to supersonic speeds quickly. If, as they claim, the airplane is efficient in the subsonic regime as well, then there is less pressure to accelerate rapidly. Efficient low-speed operation also inherently implies a lower exhaust speed (which they discuss briefly: variable high-bypass flow), which implies less noise -- for a given engine, noise power scales roughly (very roughly) linearly with exhaust velocity.

Noise from sonic booms is remarkably controllable, with sufficient work on the precise shape of the airframe. The technology to do that, high performance CFD, simply didn't exist when the Concorde was designed. They don't discuss it, but it's far too early in the design cycle for that to mean anything. Right now they're basically just trying to build the engine and convince people that a market exists at a price point they can reach. That requires design studies and concept art, but it's not yet time to be fine tuning the aerodynamics.

I'd say the technical problems, including noise, are amenable to solution if they manage to get the funding they need without too much interference. The market ones, less so. I'm sure one day we'll see supersonic airliners, but there are some *major* non-technical hurdles in the way of building anything the size of an A380.

Of course, it's wicked cool and I'd love to see it happen. Especially since the basic engine technology is also behind their Skylon SSTO spaceplane concept...

Barf Bags

Good, now we'll finally use those little barf-bags on the back of airline passenger seats.

Streamlining doesn't just apply to the aircraft...

A British company has designed an eco-friendly airliner that could make a trip from London to Sydney in under five hours.

How droll. Soon, you will be able to travel from London to Sydney in less time than it takes to negotiate security at the airport. ^_^

I still don't get it

You can (essentially) only go supersonic over the oceans, so you need routes where you can actually use all that power, say New York to Europe or LA to the Pacific rim. Next, a ticket on this beast will cost slightly less than an average working stiff's annual mortgage payments. So we need to find 300 self-important assholes who are 1) richer than they are smart 2) in too big of a hurry to spend twice as much time crossing the ocean at 1/10th the price. And of course this model only works if there's regular service, never mind the fact that you only sold 4 tickets for Wednesday's LA to Shanghai run. There were how many planes in the Concorde fleet?? There is ZERO economic chance that this will ever happen.

Thunderbirds are go!

It looks like the plane Fireflash [sfdaydreams.com] in one of the Thunderbird's [thunderbirdsonline.co.uk] shows. Okay, the engines are under the wings and not on the tail, but that's about it.

Popular Science Article

Popular Science wrote an article about this plane: Article [popsci.com]

British Technology Never Flies

The last major triumphs of British engineering to actually get built were Concorde and the Advanced Gas-cooled Reactors.

Ever since then the can't-do-won't-do attitude of Britain's "financial service economy" curtails any great technological projects. The only things that get built are science projects, with meager government funding.

Reaction Engines/Bristol Spaceplanes have some very interesting engine designs like SABRE. These are the people who designed the RB545 for Hotol (another great British triumph of procrastination over achievement).

Mark my words, this will sit firmly on the drawing board and will probably be reinvented in 20-30 years by the Chinese. The American's won't have it since they didn't invent it.

It sucks to be British unless you're in Banking or Insurance. Still, mustn't grumble. At least we're not French or German or foreign. Time for a nice cup of tea and a sit down.