China Will Resurrect the World's Largest Plane • Hacker News Board

Re: China Will Resurrect the World's Largest Plane

#81

Post by Luc » Sun, Sep 11, 2016, 5:46 PM UTC

macintux wrote: post #76

djrogers wrote: post #73

There is very little chance that story is even remotely true. The story had 2 sources - Saddam Hussein, and Mohammed Saeed al-Sahhaf aka 'Baghdad Bob' (if you don't remember him, look him up - he was a meme before the Internet made memes a thing). On top of that, the story changed from a farmer to a few peasants and back again depending on who was talking and when. It was propaganda to make the US military look weak…

Curious to what in the world this is in reply.

This I guess (last paragraph): https://news.ycombinator.com/item?id=12473552

Re: China Will Resurrect the World's Largest Plane

#82

Post by dmoy » Sun, Sep 11, 2016, 5:53 PM UTC

semi-extrinsic wrote: post #71

rayiner wrote: post #66

Earlier quoted context omitted.

Modern turbofans only stand up to their extreme operating conditions because of the use of exotic alloys and elaborate cooling techniques. Just because you know what shape a turbine blade should be doesn't mean you can copy the exotic alloy and manufacture it in a way that results in the correct crystal structure.

Not only exotic alloys, but single crystal blades. That's right, the blade is machined out of a single atomistically perfect crystal with no defects what so ever. The main point is that this reduces thermal creep, meaning you can have tighter tolerances and more power/efficiency.

Holy crap that is nuts. Towards the middle/end in here:

https://www.theengineer.co.uk/issues/june-2015-online/jewel-...

Also cool to hear them talking about automating as much stuff as possible to remove human error. Incidentally that's also how we go about software release processes where I work.

Re: China Will Resurrect the World's Largest Plane

#83

Post by commentreply » Sun, Sep 11, 2016, 5:57 PM UTC

macintux wrote: post #76

djrogers wrote: post #73

There is very little chance that story is even remotely true. The story had 2 sources - Saddam Hussein, and Mohammed Saeed al-Sahhaf aka 'Baghdad Bob' (if you don't remember him, look him up - he was a meme before the Internet made memes a thing). On top of that, the story changed from a farmer to a few peasants and back again depending on who was talking and when. It was propaganda to make the US military look weak…

Curious to what in the world this is in reply.

The above comment was probably in reply to the following:

"...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..."

Re: China Will Resurrect the World's Largest Plane

#84

Post by Someone » Sun, Sep 11, 2016, 6:15 PM UTC

"it carries a world record payload of 250 tons (to put this into comparison, it can carry around 300,000 lbs more than the US military's Boeing made C-17"

What was the writer thinking? My readers won't understand what 250 tons is, so I'll use imperial metrics, too? Net effect is that this only makes full sense to those who understand both metric and imperial units.

(I think a pound is 454 grams ('easy' to remember because that's the unit most jam is sold in in the EU (https://en.wikipedia.org/wiki/Metrication_in_the_United_King...). That would make 300,000 pounds about 135,000 kg or 135 tons, so it carries about double what a C17 can carry)

Re: China Will Resurrect the World's Largest Plane

#85

Post by Apocryphon » Sun, Sep 11, 2016, 6:23 PM UTC

Aw, I thought it meant that they're modernizing the Spruce Goose.

Re: China Will Resurrect the World's Largest Plane

#86

Post by DashRattlesnake » Sun, Sep 11, 2016, 6:30 PM UTC

dogma1138 wrote: post #52

vasili111 wrote: post #42

Earlier quoted context omitted.

Why not to just buy one aircraft and reverse engineer its engines? What is the problem with just copying exact copy of existing engine?

Because a lot of the "knowledge" comes from the engineering process much of it is trial and error and often it's not documented in the theoretical books ;) This is why it's easy to lose the ability to produce something e.g. the big rockets that NASA used to make. China can make a copy of the engine but it would not gain sufficient insight into why they chosen to design it exactly as it did so making adjustments would…

> This is why it's easy to lose the ability to produce something e.g. the big rockets that NASA used to make.

IIRC, to avoid this when they shut down F-22 production, they crated a huge number of DVDs documenting every step of the manufacturing process, so that knowledge wouldn't be totally lost.

Re: China Will Resurrect the World's Largest Plane

#87

Post by DashRattlesnake » Sun, Sep 11, 2016, 6:33 PM UTC

k_lander wrote: post #63

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.

Also, how Ukraine, out of all countries?

> Also, how Ukraine, out of all countries?

I think the Soviet Union physically based a good chunk of its military industry in Ukraine, which the country then inherited when it became independent. So when we talk about Ukraine in this context, we're talking about a former superpower.

Re: China Will Resurrect the World's Largest Plane

#88

Post by DashRattlesnake » Sun, Sep 11, 2016, 6:37 PM UTC

digi_owl wrote: post #59

Retric wrote: post #56

Earlier quoted context omitted.

It's not just rebuilding engines it's returning their weight that's a problem. The high temperatures are a result of pressure not friction. A smaller and or less dense craft has a vastly easier time during reentry. A shuttle actually works fairly well at around 1/5 the size. Lower thermal stress means no tiles. It would have a single ideally swappable engine large on board fuel and no external fuel tank. Still needs…

My understanding is that it got fatally compromised as either a 3 letter agency or the pentagon wanted to use it for satellite maintenance/retrieval. Never happened, but it still resulted in a hybrid design that was basically suitable for neither. In the end it may well have continued flying as a kind of "national pride" issue.

> a 3 letter agency or the pentagon wanted to use it for satellite maintenance/retrieval. Never happened

I think they did do satellite maintenance from the shuttle a few times, most notably on the Hubble telescope.

Re: China Will Resurrect the World's Largest Plane

#89

Post by qaq » Sun, Sep 11, 2016, 6:38 PM UTC

avmich wrote: post #80

qaq wrote: post #55

Earlier quoted context omitted.

Not that many the bulk of manufacturing was done in Ukraine what was sourced externally can be sourced from subcontractors. For example engines are manufactured by Motor Sich (Ukraine based) which is still a fairly large engine manufacturer etc.

Hydrogen engines for Energiya, RD-0120, were made in Voronezh by KBKhA, which is still producing rocket engines. However this particular engine is practically lost - can't be recreated without extensive R&D program. It's not enough to have the original manufacturer survive... Can Rocketdyne manufacture another F-1 today? So it's quite possible - though not certain - that Motor Sich wouldn't be able to create a unique…

The engine is not unique to Mria it was used on AN-124 and Motor Sich has a modernised version going through testing Д-18ТМ so should not be any issues on that front

Re: China Will Resurrect the World's Largest Plane

#90

Post by kragen » Sun, Sep 11, 2016, 6:42 PM UTC

From the title, I thought this was going to be about the Spruce Goose, but it turns out the Spruce Goose was designed only for a 75-ton capacity, not the 250 tons of the Ан-225. The Spruce Goose had a larger wingspan (97.5 m rather than 88 m) but the Ан-225 is longer (84 m rather than 66⅔ m).

It's interesting to reflect that the previous "world's largest plane," and still the one with the widest wingspan, dates from WWII. In a sense this reflects changing social priorities, and in another sense it may reflect a generalized form of Conway's law: giant aircraft are produced by giant monolithic bureaucracies brooking no dissent, like countries in wartime or totalitarian governments.

If that's the case, maybe we'll see more such planes if the wars in Syria and other places continue to spread, pushing countries like the US and the EU powers onto more of a wartime footing. But it's not clear they'll be strategically beneficial for fighting in the Drone Age; they're too hard to build and too easy to destroy.