A plane that will be able to fly anywhere in the world within 4 hours

http://www.sciencealert.com/this-plane-will-be-able-to-fly-anywhere-in-the-world-within-4-hours

by dnetesn • 12 years ago

254 110 12 years ago

Involute• 12 years ago

Odd that a picture of dead people (Palermo catacombs, I'm guessing) shows up beside this headline in my RSS reader (Feedly).

tensor• 12 years ago

Not odd at all. If you scroll down there are links to other articles. The last one is a photo of the catacomb mummies. Your fead reader simply chose the wrong photo from those on the page.

dkopi• 12 years ago

Hopefully, they've learned a few lessons from the Concorde. http://en.wikipedia.org/wiki/Concorde

tim333• 12 years ago

Seems like cool technology. I wonder if it'll actually get to fly.

chx• 12 years ago

Cool. This http://en.wikipedia.org/wiki/Reaction_Engines_A2 is six years old. What's the news?

gilgoomesh• 12 years ago

There is no new information here. It looks like sciencealert.com got its information from businessinsider.com's Dec 11, 2014 article which references a "new video" as its source:

https://www.youtube.com/watch?v=yLD1TPsEi3E

but that "new" video is from 2012.

jessriedel• 12 years ago

Honest question: Can someone explain why a Mach 5 air-breathing engine is important for reaching low-Earth orbit (~Mach 25)? I still don't understand after watching the video.

I recall from a video interview that Elon Musk is skeptical of the utility of air-breathing engines for economic access to LEO since, as he put it, the atmosphere is "thick as soup" and you basically want to get out of it ASAP before you get up to orbital velocity. Breathing air up to Mach 5 allows you to save some weight, but you have to bring enough liquid O2 for the rest of your acceleration from Mach 5 to Mach 25. So is the idea that this modest savings in weight is all that's needed for a single-stage to orbit?

pwnna• 12 years ago

Some background: This company's engine is based on its previous design, the SABRE engine. That engine is designed to reach an altitude at 28km, flying at Mach 5 (which works out to be about 1.5km/s at that altitude, ~15% of orbital velocity at LEO). After that the engine is designed to switch to a rocket mode, where it burns fuel and oxygen it brought, rather than taking it from the atmosphere.

Since the an air breathing engine is much more efficient (10x) than a traditional rocket engine, it allows the launch vehicle to conserve mass that would otherwise be used to overcome the high drag encountered in lower altitudes. You can roughly think of this as a rocket with all of its mass being launched at 28km, with a velocity of Mach 5 already.

"Getting out of the atmosphere" is a pretty vague statement. Atmospheric pressure and density is about 1-2% that of the ground. So drag at these altitudes will be less. However, some quick and dirty calculations by me makes this seem like a relatively small number compared to the amount of energy it takes to actually get to orbit. Quick search indicates the same as well[1].

However, a "thick" atmosphere is something that has to be dealt with. For example, rockets also need to overcome pressures that exists at lower altitudes. If you take a look at any rocket launch videos, you will notice that the exhaust at higher altitudes (typically about 2-3 minutes after launch) will expand outwards with respect to the rocket itself. This means that the flow out of the rocket engine is "underexpanded", making the engine less efficient than it would be otherwise. By starting your rocket engine at a higher altitude, you can improve the efficiencies by designing your rockets to lower atmospheric pressures (I don't know if this is done for the SABRE engine, but this is theoretically possible).

So based on these, the main motivation for this is probably for the mass savings and efficiency. Additionally, this engine presents itself with potentials for complete reusability, which is very attractive as most current launch cost is from the unrecoverable launch vehicle itself.

[1]: forum.nasaspaceflight.com/index.php?topic=9959.msg189860#msg189860

iwwr4• 12 years ago

So based on these, the main motivation for this is probably for the mass savings and efficiency.

They plan to invest all those savings into a single-stage-to-orbit launcher. It's appealing in a similar manner that SpaceX's stage-return strategy, but in a one-spacecraft package. High-mach aircraft will find other uses too besides orbital launchers.

As for saving a 'mere' 15% at launch that can be crucial from a payload perspective in the rocket equation.

vilhelm_s• 12 years ago

You can make a SSTO even without airbreathing, this is how the VentureStar would have worked.

I think there are two benefits. One is that the oxygen takes up most of the fuel mass (e.g. the first stage of a Delta IV carries 173 tons of oxygen and 30 tons of hydrogen), so getting some from the atmosphere is a big weight saving.

The other is that even if the air-breathing part on works in lowest part of the atmosphere, the denser parts of the atmosphere costs a lot of fuel because the rocket has to go slow and incurs more gravity drag. For the Falcon 9, first-stage separation occurs at Mach 6, roughly the same speed that the Skylon would switch from air-breathing to liquid oxygen. But in fact, the first stage is the biggest part of the rocket.

vlasev• 12 years ago

Let's see. The sabre engine has a closed cycle specific impulse of 450, which gives an effective exhaust velocity of 4.4 km/s. LEO requires about 7.8 km/s velocity while mach 5 is 1.7 km/s. In one case you accelerate from 0 to 7.8 km/s an in the other from 1.7 to 7.8 (for 6.1 km/s delta-v). The first figure gives a mass ratio of 5.9 while the second one gives you ratio of 4.0. You save about 1/3 of the initial mass if you only have to burn on a closed cycle from Mach 5 upwards.

In reality gravity is a tough mistress so actual rockets launching from a pad require about 9.0 km/s delta-v because they lose a substantial amount due to the gravity losses of climbing up from Earth's gravity well. This is especially true for the first few km's of altitude where the thrust-to-mass ratio is quite low. Potentially, the skylon will eliminate most of those gravity losses by effectively launching from 26km altutude at mach 5 (i'm ignoring the relatively modest fuel consumption for reaching this state - the specific impulse is about 3500).

Assuming a delta-v of 9.0 km/s needed for a single stage rocket gives a mass ratio of 7.7. This means that the skylon should save about 48% of the initial mass required by a SSTO rocket launching from sea level.

sitkack• 12 years ago

Isn't that mass savings mostly in the 330k$ of fuel for the first stage? The economic argument is in the reusable hardware.

weterley• 12 years ago

The atmosphere is thick as soup, and that's why lift and flight are possible. Conventional rockets are way too heavy to fly (in the literal sense); they just bring tons of fuel and ditch the containers in stages.

SSTO instead brings little enough fuel (weight) that it can fly itself through the soupy part, which is much more efficient (by like an order of magnitude), on top of not requiring oxidizer for that phase. The longer you can stretch out the aerodynamic phase (i.e. the faster and higher you engines breathe), the less oxidizer you need to bring.

If you crunch the numbers (which apparently they did), you get that the equations work out to needing an engine that will stretch the aerodynamic phase up to mach 5. If your plane can't do that, getting to orbital velocity requires you to bring too much fuel for your plane to fly in the first place, and you might as well build a conventional rocket.

grondilu• 12 years ago

The short answer is that Mach 5 may be only a fifth of Mach 25, but since the rocket equation is logarithmic, this speed gain actually matters a lot. Just enough to go to orbit in a single stage, anyway. According to ReactionEngines calculus, that is.

moron4hire• 12 years ago

It's basically the Sears-Haack body with some engines bolted on: http://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body

0x0• 12 years ago

Is it still 25 years away from being available to commercial airlines, like the wikipedia article mentions? Can't wait! :)

nickhalfasleep3• 12 years ago

They talk over and over about their engine, when there are plenty other hard problems they do not have solutions for. For instance light enough cryogenic fuel tanks don't exist. This was part of the reason the Venture Star / X-33 never met their weight budget.

ChuckMcM• 12 years ago

Came here to say the same thing. And note that you're "burning" 400MW of energy in the heat exchanger (transferring it to the helium) at some point you have to re-cool that helium back to liquid) if you outgas the helium you are a net loss because helium has a limited supply. Doing it with hydrogen doesn't get nearly the thermal mass. So it is a really really cool engine, but it remains to be seen how practical it can be.

The second thing, consider the experience from the SR-71. To stay light and still be able to withstand the frictional heating of the air at mach 5 requires some pretty exotic materials. And matching thermal properties for materials at mach 5 vs sub mach. Covering the whole thing in thermal tiles adds weight which comes out of the payload.

To me, adding on the possibility that it could be some sort of Mach 5 super airliner, suggests that the practicalities of it as an SSTO platform are perhaps not nearly so compelling as once thought. Fortunately they were not talking about the multi-gigawatt ground lasers to boil hydrogen. That idea, while nominally physically possible, is impractical to imagine the rest of the world being "ok" with.

digi_owl2• 12 years ago

http://www.reactionengines.co.uk/sabre_howworks.html

Seems that they are using the heat absorbed from the air, via the helium to eventually heat the hydrogen going into the engine.

http://www.reactionengines.co.uk/images/sabre/sabre_cycle_10...

iwwr4• 12 years ago

I thought the liquid helium is only for an engine testbed. Production Skylon engines will use liquid hydrogen and oxygen, effectively using their criogenic fuel as a heat sink.

pja2• 12 years ago

The plan is to dump the waste heat into the cryogenic fuel I believe.

cstross2• 12 years ago

To me, adding on the possibility that it could be some sort of Mach 5 super airliner, suggests that the practicalities of it as an SSTO platform are perhaps not nearly so compelling as once thought

Ding!

Yeah, that was my reaction. If SpaceX get the reusable first stage tech running on Falcon 9, then they shave $40M off the cost of each launch (the first stage fuel and oxidant costs $300,000; the stage itself, including nine motors, costs around $40M). Even if each flight costs a couple of mill to refurbish and can only fly 10 times, they'll still have cut the $40M price to around $6-7M.

Meanwhile, here's Skylon, a decade late off the starting blocks. With the Sabre engine running on liquid hydrogen, which is a beast to handle, with valuable He as a consumable.

Frankly, the airliner option looks silly to me. The only real target market for a Mach 5 in-air vehicle is the military.

madaxe_again4• 12 years ago

'tis a shame that whatever Starlite (http://en.wikipedia.org/wiki/Starlite) is is lost knowledge.

Freestyler_3• 12 years ago

How does this all work in space?

someotheridiot• 12 years ago

They can't maintain orbit at Mach 5, it's just not fast enough. IIRC you need Mach 25 for LEO.

mrfusion• 12 years ago

I hadn't heard about the fuel tank problem before. Where can I learn more?

Do you think new materials like graphene will dramatically change spaceflight when they're mass produced?

madaxe_again4• 12 years ago

s/when/if/

Graphene may yet be a pipe dream. If we manage to manufacture it in large and perfectly uniform quantities, it's a wonder-material. If we don't - it could make for slightly better carbon fibre composites.

nickhalfasleep3• 12 years ago

In short, cryogenic liquids, especially Hydrogen, is incredibly destructive to any container. It's pretty much the smallest molecule around and will wiggle into and make anything brittle over time.

http://www.nasaspaceflight.com/2006/01/x-33venturestar-what-...

jccooper• 12 years ago

There are now LH2 composite tasks at a decent tech readiness level

http://www.nasa.gov/press/2014/august/nasa-completes-success...

nickhalfasleep3• 12 years ago

That is a tank serviceable for a few hours which keeps itself cool on the pad with boil-off. An economic aircraft would have to stand thousands of hours with airframe stresses.

minor_nitwit• 12 years ago

Ok, these guys claim to have invented a great engine, really just the pre-cooler. Why are they trying to build a plane instead of licensing it to others? That seems to be several orders of magnitude more difficult and increases the likelihood of failure.

imaginenore2• 12 years ago

Do you know any Mach 5 planes?

jschwartzi• 12 years ago

Does he know of anyone in the tightly-regulated airline industry who would be crazy enough to build a completely new airframe and engine around a currently-experimental precooler?

madaxe_again4• 12 years ago

Sure. The X-51. http://en.wikipedia.org/wiki/Boeing_X-51

paulftw• 12 years ago

Where does this liquid helium come from, and more importantly where does it go after it's been heated? Im guessing they release it into atmosphere, so is there enough helium to mine for this plane to go mainstream?

sparkzilla• 12 years ago

It says in the Wikipedia article that: "The key design feature for the Scimitar engines is the precooler, which is a heat exchanger that transfers the heat from the incoming air into the hydrogen fuel."

sargun• 12 years ago

Hydrogen? How are they storing that efficiently?

encoderer2• 12 years ago

Wait. Wouldn't this be a closed system? I can't imagine they're outgassing helium?

NickNameNick• 12 years ago

They aren't.

The helium is cooled by the hydrogen going to the engine.

You can't run the pre-cooler on the hydrogen directly, because the hydrogen infiltrates the welds (and everything else) causing hydrogen embrittlement, which will quickly tear the heat exchanger apart.

http://en.wikipedia.org/wiki/Hydrogen_embrittlement

Thomashuet2• 12 years ago

This is bullshit, -273°C is absolute zero so unless the plane is on fire, it can't cool down the air by more than 1000°C.

nmjohn• 12 years ago

Rocket engines get extremely hot: http://en.wikipedia.org/wiki/Rocket_engine#Cooling

Thomashuet2• 12 years ago

They pretend the air is precooled, not cooled after going through the engine.

ms013• 12 years ago

Air entering the engine at high speed is heated significantly due to compression.

tdicola• 12 years ago

I think I've read this exact same story for the last 25 years. Will believe a Mach 5+ commercial jet when I see it.

rsl7• 12 years ago

I think I still have some marketing materials for the National Aerospace Plane from the late 80s

cabalamat• 12 years ago

It goes back longer than that; the HOTOL project started in 1982 -- http://en.wikipedia.org/wiki/HOTOL

johan_larson• 12 years ago

And even earlier: http://en.wikipedia.org/wiki/Supersonic_transport

I suspect this is one of those Big Challenges that keeps tempting aeronautical engineers, and they try to apply the pushing-the-envelope high tech of their era to it. The problem seems to be the economics. There aren't a lot of people who are willing to pay 10x prices (or whatever) for 3x reductions in travel time.

kbart• 12 years ago

My thoughts too. The main reason is not the engines, but the frame itself. It's not very commercially viable spend days in a hangar, after few hours of flight, scanning for the micro faults.

jzwinck• 12 years ago

The article title refers to a "plane engine" not a "plane." There is a huge difference: the passenger plane airframes everyone knows and flies on are made by totally separate companies (Airbus, Boeing) from the engines (Rolls Royce, GE, Pratt & Whitney).

A great engine will get you nowhere without a great airframe, and when you start talking about supersonic passenger service, you have to add politicians as well. For example, the Concorde briefly flew between London and Singapore but was stopped partly due to complaints from the Malaysian government. And of course the Concorde is long since retired, despite no comparable replacement existing; this has nothing to do with its engines not being good enough.

rtpg• 12 years ago

Also important to mention why Concordes got cancelled: even with cheap oil, there wasn't much demand for the plane. After a certain point, not much changes between a 4 hour flight and an 8 hour flight, especially if you have red-eye flights. Unless we figure out a way to have fast planes be cheaper to run than current models, then markets seem to show lack of interest in a Concorde-like

qq662• 12 years ago

The reason that not much changes between a 4 hour flight and an 8 hour flight is that the journey adds about 2 hours on each end, making it a 8 hour vs. 12 hour journey. (1 hour to the airport and 1 hour at the airport).

Urban transit systems and airport security/boarding procedures will need to get a lot more efficient before supersonic flight will be commercially viable.

smikhanov• 12 years ago

Correct, especially with the added time of getting to, from and through the airports.

Some materials about a short-lived Hindenburg airship (http://www.retronaut.com/2011/04/inside-the-hindenburg-in-co...) mention its travel time between Europe and North America to be 40+ hours. I wonder, if they were available today, would there be a demand for this type of travel? For me the choice between a seat in 8 hour flight or a comfortable cabin in 40 hour is often not in favour of speed.

markbnj• 12 years ago

I agree with this, and most of the reservations expressed, but just to note: he said Europe to Australia in 4 hours. That's... more like 22 hours now, right? That would be a very significant improvement.

lotharbot2• 12 years ago

the Concorde used about triple the fuel per passenger of other aircraft of its era (like the 747). Even with relatively cheap oil, that added fairly substantial cost.

Additional factors that led to its demise:

- it was a very loud aircraft, and couldn't go supersonic over populated areas due to sonic booms. This led to significant limitations on viable routes.

- it didn't have the fuel capacity to make trans-pacific flights. This also led to limitations on viable routes.

- Concorde required specialized pilot training, specialized maintenance, and even a flight engineer (which more modern jets don't require).

- supersonic flight wears out airframes. I worked in a museum with Concorde G-BOAG, and could see several spots where the airframe had been patched in more substantial ways than our other similarly-aged or older airliners (Eisenhower's 707-based Air Force One and the prototype 727, 737, and 747's.) Airbus didn't want to keep maintaining the airframes given the condition they were already in.

Zaephyr• 12 years ago

So is the breakthrough just the pre-cooler, or the pre-cooler together with the scimitar engine?

It sounds like the innovation is the helium pre-cooler, but even at that it's hard for me to understand whether their advancements are in working with liquid helium for a coolant or in the airflow cooling (both)?

I don't do anything remotely like this in my day job.

acd• 12 years ago

The cool part is that this plane will do US to Europe in 1-2 hours which is a game changer.

Given how fast it flies, how much would the tickets cost?

tomelders2• 12 years ago

I get the impression that the passenger flight times are more marketing talk intended to frame the technical achievement in terms people can understand rather than an actual intended use case. Reaction Engines do have plans to use the engine on a passenger plane, but the Skylon is designed to take payloads up into space cheaply.

http://www.reactionengines.co.uk/lapcat.html

vinayp10• 12 years ago

Richard branson was talking about doing this:

http://www.businessinsider.com/richard-branson-supersonic-pl...

BendertheRobot• 12 years ago

But, what about the carbon impact of this? It will only be available for one percenters, no?

robotresearcher• 12 years ago

A hydrogen/oxygen engine emits only water. You can choose to get the hydrogen from water using from a non-carbon energy source, for a completely carbon emission free system.

Animats3• 12 years ago

This company has been in business since 1989, and has never produced anything. Here's their own statement of their own history:

http://www.reactionengines.co.uk/about_history.html

That's not encouraging. They own a machine shop company and a sheet metal company. They should have built a working model of something by now.

tomelders2• 12 years ago

That sort of sentiment is why we can't have nice things. These thing stake time.

Remember, this isn't a kick-starter campaign. They're not trying to dupe other people out of money on some hair-brained scheme. This work has been reviewed by the British Interplanetary Society and the ESA. It's real science, tackling a real problem.

I'll make a bet with you now. In 15 years, the Sabre Engine will be carrying more payloads into space than anyone else, and for less money than anyone else can offer.

darkmighty• 12 years ago

http://longbets.org/

hahainternet• 12 years ago

They should have built a working model of something by now

They built and demonstrated a reduced scale engine for the ESA. If you think it's that easy just to build a spacecraft when you own a machine shop and a sheet metal company then you have a lot of reading ahead of you.

Animats3• 12 years ago

They demonstrated a reduced-scale pre-cooler. See Aviation Leak: http://aviationweek.com/blog/esa-validates-sabre-engine-tech...

The point is that their PR describes something two orders of magnitude beyond what they've done.

pothibo• 12 years ago

And then, once they achieve fame, people will name them as overnight success.

Big ideas, as other suggested, takes time and are often built through trials and errors.

Also, the ESA has said that their model is sound and that all the experiment needed to validate the idea were successfully completed[1].

http://en.wikipedia.org/wiki/SABRE_%28rocket_engine%29

outworlder3• 12 years ago

They are also funded by what amounts to ramen money.

untilHellbanned• 12 years ago

Bored Elon musk is already doing this in 3 hours.

https://twitter.com/boredelonmusk

pariya• 12 years ago

I actually bet he reads through that Twitter account and rolls his eyes because he has already secretly invented half of it.

jmnicolas• 12 years ago

It looks like a marriage between a SR-71 Blackbird and a Concorde.

At 1.1 billion each, it's about 10 times as expensive as a Concorde. I hope they will find a way to keep it profitable.

martinko• 12 years ago

The A-380 costs about 414 million usd and can carry ~500 people. A flight from Europe to Sydney takes north of 22 hours (not counting stop-overs).

Off the top of my head, this new plane seems like a pretty good deal, doing Europe to Sydney in ~4 hours with 300+ passengers for a unit cost of 1.1 billion.

hvidgaard2• 12 years ago

You cannot ignore fuel cost and investment to handle the new fuel. We'll see what happens, but the most compelling thing to me seems to be the fact that it burns hydrogen and not kerosene which seems to be more environmental friendly, but I'm no chemist.

EGreg• 12 years ago

I hope they dont make too many of these planes that breathe oxygen. We may need some for humans.

wintermute306• 12 years ago

I couldn't help but hum the British national anthem while reading this.

mst• 12 years ago

I tried to join you but for some reason my brain decided to produce the Imperial Death March instead.

Gravityloss• 12 years ago

Title reminds me of this 30-minute delivery anywhere in the world (much older technology): http://designobserver.com/feature/blast-door-art-cave-painti...

A plane that will be able to fly anywhere in the world within 4 hours

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