Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

China Will Resurrect the World's Largest Plane

popsci.com

Post reply on HN
Print view View original

31–40 of 119 posts

Re: China Will Resurrect the World's Largest Plane

#31

Post by crawshaw »

wallace_f wrote: post #28
ovi256 wrote: post #20

It's obvious to me that China doesn't care that much about the AN-225 design as for the design of the D-18 turbofan. They still can't design or manufacture a heavy turbofan domestically. This has seriously hampered their heavy airlift project (the Y-20, who first flew using Soviet-designed low-bypass 12-ton thrust D-30 fans, which killed its range). The domestic WS-20 turbofan design that was supposed to power the pr…

Why is it difficult enough that not even a nation state as large and powerful as china has obstacles to develop a heavy turbofan? With respect to other tech they've developed I don't know what is technologically difficult here -- I'm asking genuinely as a layman, it's not a rhetorical statement of disagreement.

Fluid dynamics and combustion chambers. It's rocket science, a long, expensive trial-and-error development process. And unlike other sciences, most of the results are never published so each entity has to recreate the foundations themselves. It takes money, time, and dedicated careers.

Re: China Will Resurrect the World's Largest Plane

#32

Post by to3m »

ksrm wrote: post #11
to3m wrote: post #5

"84 meters ... 88 meters ... 250 tons ... 300,000 lbs"

For those wondering: 250 tons = 227 tonnes (227,000 kg) 300,000 lbs = 136 tonnes Why the second figure wasn't just given as 150 tons I have no idea.

In fact the An255 can carry 250,000kg...

(My initial complaint was just with the units mismatch. But, as is often the case, this is just the tip of the iceberg. My rule of thumb remains in force: any time an article mixes up metric/imperial/US Customary units, you can basically ignore that part of it.)

Re: China Will Resurrect the World's Largest Plane

#33

Post by icegreentea »

wallace_f wrote: post #28
ovi256 wrote: post #20

It's obvious to me that China doesn't care that much about the AN-225 design as for the design of the D-18 turbofan. They still can't design or manufacture a heavy turbofan domestically. This has seriously hampered their heavy airlift project (the Y-20, who first flew using Soviet-designed low-bypass 12-ton thrust D-30 fans, which killed its range). The domestic WS-20 turbofan design that was supposed to power the pr…

Why is it difficult enough that not even a nation state as large and powerful as china has obstacles to develop a heavy turbofan? With respect to other tech they've developed I don't know what is technologically difficult here -- I'm asking genuinely as a layman, it's not a rhetorical statement of disagreement.

Should probably begin by saying that there's no fundemental reason why China could not eventually develop their own modern turbofans without outside assistance. But obviously now is better for China.

Designing and building modern turbofan engines is incredibly dependent on your mastery of materials science and fabrication. These are areas of science and engineering that are notoriously "art like" or even "black magic like". The accrued knowledge that sits in Rolls-Royce or GE or Pratt-Witney don't really exist in textbooks, and they aren't taught in classes either. This knowledge and know how was generated over 60 years of trial and error, and are jealously guarded, not just by the manufacturers, but also by their governments.

Things to consider: modern turbine blades are already pushing the absolute edge of lightweight-temperature resistant materials. And then modern designs will run these blades at temperatures that are nominally above the material failure point, because we've come up with ways to cool the structures. Oh, and the temperature resistant alloys in use? Secret. Empirically determined, and likely unique.

Re: China Will Resurrect the World's Largest Plane

#34

Post by rmelly »

icegreentea wrote: post #33
wallace_f wrote: post #28

Earlier quoted context omitted.

Why is it difficult enough that not even a nation state as large and powerful as china has obstacles to develop a heavy turbofan? With respect to other tech they've developed I don't know what is technologically difficult here -- I'm asking genuinely as a layman, it's not a rhetorical statement of disagreement.

Should probably begin by saying that there's no fundemental reason why China could not eventually develop their own modern turbofans without outside assistance. But obviously now is better for China. Designing and building modern turbofan engines is incredibly dependent on your mastery of materials science and fabrication. These are areas of science and engineering that are notoriously "art like" or even "black magic…

Pretty much this. Incredibly hard to design from scratch; cheaper to buy an existing design and start from there.

Re: China Will Resurrect the World's Largest Plane

#35

Post by fma »

icegreentea wrote: post #33
wallace_f wrote: post #28

Earlier quoted context omitted.

Why is it difficult enough that not even a nation state as large and powerful as china has obstacles to develop a heavy turbofan? With respect to other tech they've developed I don't know what is technologically difficult here -- I'm asking genuinely as a layman, it's not a rhetorical statement of disagreement.

Should probably begin by saying that there's no fundemental reason why China could not eventually develop their own modern turbofans without outside assistance. But obviously now is better for China. Designing and building modern turbofan engines is incredibly dependent on your mastery of materials science and fabrication. These are areas of science and engineering that are notoriously "art like" or even "black magic…

This being China...what are the chances they can buy existing designs and reverse engineer them and improve then so they don't start from scratch. They've done it before...

Re: China Will Resurrect the World's Largest Plane

#37

Post by eCa »

SandB0x wrote: post #6

Writers! Please don't use "exponentially", which has a precise meaning, in place of a more modest word such as "greatly". > "China buying and building An-225s would exponentially increase its power capabilities not just in Asia, but across the world."

I'm sure that with a few more years of improper usage it will go the way of literally, which literally means either literally or figuratively.

Re: China Will Resurrect the World's Largest Plane

#39

Post by icegreentea »

fma wrote: post #35
icegreentea wrote: post #33

Earlier quoted context omitted.

Should probably begin by saying that there's no fundemental reason why China could not eventually develop their own modern turbofans without outside assistance. But obviously now is better for China. Designing and building modern turbofan engines is incredibly dependent on your mastery of materials science and fabrication. These are areas of science and engineering that are notoriously "art like" or even "black magic…

This being China...what are the chances they can buy existing designs and reverse engineer them and improve then so they don't start from scratch. They've done it before...

Well, they've almost certainly been trying that. And as the OP said, it hasn't been paying off in a big way. If they've been doing it (I'm guessing they have), then they've probably benefitted, just not enough for the big win.

Once you get into materials and fabrication, having a finished example to examine is rarely going to lead to a big win. If the secret sauce is in the fabrication (HOW do you make a single crystal blade? HOW do you inflate corrugated titanium? HOW do get this type of grain structure with this nickel-iron-manganese mix? HOW do you get a laser weld in this impossible again?), then a single example isn't -THAT- useful.

Reversing engineering a modern turbofan(remember, the basic principles of turbofans are well known) is more akin to reverse engineering Intel's fab process by peaking at a finished i7 (with AFM and electron microscopes) than reverse engineering say... a sensor fusion module once you get the assembly code.

Which is why the technology transfer associated with the engine deal is a big deal. It should (I mean, its possible that the terms are all fucked up) give the Chinese an oppourtunity to learn all of these hows and whys (albeit for a slightly dated design, but still a relatively modern one).

Re: China Will Resurrect the World's Largest Plane

#40

Post by speeder »

jandrese wrote: post #24
SideburnsOfDoom wrote: post #17

Is an aircraft of this size economical, or is it a fuel hog useful only for carrying huge single-piece cargos that smaller aircraft cannot? Is it useful, or is it sheer size-vanity?

The article seems to think that it will have military use, but I personally don't see the big advantage of lugging 4 tanks in one plane instead of splitting them across two planes. If the plane were economical for general cargo lift they would have made more than one.

There are other military uses for stupid-huge planes, beside quantity of stuff you carry:

1. You can carry huge tanks (instead of several smaller ones), including ones that were NOT intended for that, meaning you can surprise an enemy by deploying some weird weapon where he doesn't expect.

2. You can carry trains, and then use those to carry the rest.

3. You can carry other airplanes, for example if you end in a war of attrition and need to crank out planes as fast as possible, it might be an interesting idea to make them even far from the front, and ferry the plane parts to the front (then assemble there, and use them).

4. And most interestingly, it can carry gigantic parts of whatever you need, warship propellers, munition factory machinery, and so on...

It is tempting to think it would be interesting to use as bomber or paratrooper plane, deploying a huge amount of bombs in the same place and levelling it completely... but this would be a terrible idea, a plane that big is probably a huge target, people would attempt to shoot at it even with small arms, and it is not impossible to get lucky with them (happened at least once in Iraq War for example, when a random farmer downed a US helicopter right on the start of the war with his hunting rifle... the chance of it working was tiny, the rifle didn't even had the range to ever reach the helicopter, but somehow, it did...)

Post reply on HN