China Considers Building a Big Rocket

[Tuckerfan]

Seems they might want to use it to go to the Moon. (http://www.bbc.co.uk/news/science-environment-10762634)
Chinese engineers are considering a new super-powerful engine for the next generation of space rockets, say officials.

According to Li Tongyu, general manager of the marketing department at the China Academy of Launch Vehicle Technology (CALT), engineers are currently studying a rocket engine with the thrust of 600 tonnes, burning highly potent liquid oxygen and liquid oxygen propellant.

If China succeeds in the development of such power, it would increase the nation's capabilities in space by orders of magnitude.

For comparison, China is currently well in the development of its most powerful rocket to date - Long March-5 - that would sport engines with the thrust of 120 tonnes.

"Rockets (with 600-tonne thrust engines) would only be justified for things like sending humans to the Moon, if such projects are approved," Li Tongyu told BBC News.

[Damburger]

LOx/LOx? Damn those Chinese are smart, getting that combination to work...

[Daggerstab]

Obviously, it's a fusion engine. :)

[mugaliens]

...engineers are currently studying a rocket engine with the thrust of 600 tonnes...

Let's see: 600 tons * 2,000 lbs/ton = 1.2 million lbs of thrust per engine.

Meanwhile, Saturn V's F-1 (SA-504 variant) was rated at 1.522 million lbs, 27% greater and 50 years earlier than this "new super-powerful engine." (first successful full-scale static firing of an F-1 was performed in March, 1959).

I'm not knocking China's efforts (carry on!). Just the overly sensationalistic article.

[Larry Jacks]

Those are probably metric tons, 1000 KG or about 1.32 million pounds. Still not as powerful as an F-1 but not too shabby, either.

[KaiYeves]

I read that as "Big Robot" for some reason...

[kamaz]

A bit smaller than Saturn V, so the payload would be smaller as well. Shouldn't matter, because we can now accomplish the same with smaller payloads.

It may be 50 years late, but a moon landing would have an immense propaganda value, at least for their own citizens: "Maybe we are 50 years late, but the point is that now we can, and the US can't!"

[Garrison]

Looking up the figures one of these engines would be more powerful than the Falcon 9 first stage engines combined, that's a lot of engine. :)

[Parallax M86]

Looking up the figures one of these engines would be more powerful than the Falcon 9 first stage engines combined, that's a lot of engine. :)

Indeed. :)

The article says "tonnes" so those are metric tons: 2,205 lbs.

It says the Long March 5 would generate around 3,000 tonnes of thrust at liftoff.

3,000 "tonnes" (3.000 tonnes for our international readers) of lbs-force would be 6,615,000 (6.615.000) lbs-force at liftoff. Making it the 5th most powerful rocket ever built, in terms of thrust (not necessarily lifting capacity). Just behind the Soviet N-1, the American Saturn V, the Soviet Energia and the American STS. Nothing to sneeze at.

Of course the article doesn't mention that liquid rocket thrust force is greatest at altitude after Max Q. Thrust at liftoff is usually only 85-90% of what it becomes at altitude.

[Damburger]

How is someone building an F-1 class engine not big news? Yes, it was done in the 1960s, but it hasn't been done since. Current launchers lurk around the 20-25t payload range so its unusual and thus newsworthy for a major space power to announce a substantially larger rocket.

Just as the media didn't ignore the Ares I and Ares V plans on the basis that SSME and SRBs are 1970's technology.

(Also, a smaller engine might not mean a smaller payload, as you don't know the configuration of the launcher - plus 2010 China probably has access to better materials and better engineering techniques than 1960 America and thus might get a better mass fraction)

[Larry Jacks]

How is someone building an F-1 class engine not big news? Yes, it was done in the 1960s, but it hasn't been done since.

Not quite accurate. Consider the specs on the Russian RD (http://www.astronautix.com/engines/rd170.htm)-170 engine used on the Energia:

Engine Model: RD-170.
Manufacturer Name: RD-170.
Government Designation: 11D520.
Designer: Glushko.
Developed in: 1981-93.
Application: Energia strap-on.
Propellants: Lox/Kerosene.
Thrust(vac): 7,903.000 kN (1,776,665 lbf).
Thrust(sl): 7,550.000 kN (1,697,300 lbf).
Isp: 337 sec.
Isp (sea level): 309 sec.
Burn time: 150 sec.
Mass Engine: 9,750 kg (21,490 lb).
Diameter: 4.02 m (13.17 ft).
Length: 3.78 m (12.40 ft).
Chambers: 4.
Chamber Pressure: 245.00 bar.
Area Ratio: 36.87.
Oxidizer to Fuel Ratio: 2.60.
Thrust to Weight Ratio: 82.66.
Country: Russia. Status:
Development ended 1976.
First Flight: 1987.
Last Flight: 1988.
Flown: 12.

There has not been a lot of work on really big engines for a long time because there hasn't been a lot of need for Really Big Rockets.

[Damburger]

Interesting that both Really Big Rockets which actually flew successfully (Saturn V and Energia) used as a starting point a massive, LOx/Kerosene engine in the first stage, whilst current (western) Really Big Rocket proposals all seem to prefer SRBs to provide large take-off thrusts. Yes, you could technically count the shuttle stack as a RBR with the orbiter minus the engines as its payload, but it has never flown a mission in that capacity. If you were to include that I could then include even more LOx/Kerosene based RBRs that didn't actually fly (N-1, Sea Dragon etc.).

Seems odd that the current trend is to move away from what has actually shown to work.

[Tuckerfan]

I read that as "Big Robot" for some reason...
No, that's Japan. (http://www.escapistmagazine.com/news/view/101521-New-Lightsaber-Wielding-Giant-Gundam-Finally-Complete)
The full-scale replica of the titular giant robot in Mobile Suit Gundam is fully armed and operational over in Japan once more.

Almost exactly a year ago, the life-size 1:1 scale replica of the RX-78-2 Gundam was completed in Odaiba, Japan. Then, the Japanese took it down, because they apparently hate things that are awesome. Then, they decided to put it back up again, only this time they'd be giving it its iconic "beam saber" weapon.:D

[mugaliens]

It may be 50 years late, but a moon landing would have an immense propaganda value, at least for their own citizens: "Maybe we are 50 years late, but the point is that now we can, and the US can't!"

We most certainly can. We don't for two reasons:

1. Been there, done that, and got the t-shirt.

2. We have yet to identify any justifiable reason for returning.

[Antice]

I find it hard to believe that the Chinese will go to the moon just for the propaganda value. If they go at all it will be for other reasons.
Maybe they didn't get the memo about moon resources being to expensive to exploit or something? :rolleyes:

Bad humor aside. I do not know enough about the chinese space program to comment on wither a HLV makes sense or not for them. it can do if they lack the technology to even start to contemplate major orbital assembly and fuel depot centric architectures.

[Parallax M86]

We most certainly can. We don't for two reasons:

1. Been there, done that, and got the t-shirt.

2. We have yet to identify any justifiable reason for returning.

Possible large amounts of tritium.

[Parallax M86]

How is someone building an F-1 class engine not big news? Yes, it was done in the 1960s, but it hasn't been done since.

Not quite accurate. Consider the specs on the Russian RD (http://www.astronautix.com/engines/rd170.htm)-170 engine used on the Energia:

Engine Model: RD-170.
Manufacturer Name: RD-170.
Government Designation: 11D520.
Designer: Glushko.
Developed in: 1981-93.
Application: Energia strap-on.
Propellants: Lox/Kerosene.
Thrust(vac): 7,903.000 kN (1,776,665 lbf).
Thrust(sl): 7,550.000 kN (1,697,300 lbf).
Isp: 337 sec.
Isp (sea level): 309 sec.
Burn time: 150 sec.
Mass Engine: 9,750 kg (21,490 lb).
Diameter: 4.02 m (13.17 ft).
Length: 3.78 m (12.40 ft).
Chambers: 4.
Chamber Pressure: 245.00 bar.
Area Ratio: 36.87.
Oxidizer to Fuel Ratio: 2.60.
Thrust to Weight Ratio: 82.66.
Country: Russia. Status:
Development ended 1976.
First Flight: 1987.
Last Flight: 1988.
Flown: 12.

There has not been a lot of work on really big engines for a long time because there hasn't been a lot of need for Really Big Rockets.

Well, they did make a spinoff of the RD-170 since the early 80s. The Ukrainian Zenit rocket uses a single RD-171 engine, a more powerful derivative of the RD-171. Technically the RD-171 is the most powerful liquid engine ever built. Though the F-1 still has it beat in terms of power from a single chamber/nacelle.

http://www.astronautix.com/engines/rd171.htm

http://www.astronautix.com/stages/zenit1.htm

It provides 1,839,191 lbf (vac) of thrust.

And the RD-172 (I don't think it's ever been built though)

http://www.astronautix.com/engines/rd172.htm


But that's the last RBR engine ever built so far. If the Chinese Long March 5 engines are built to the specs in the article it would be the fourth-most powerful liquid rocket engine ever built.

[kamaz]

Possible large amounts of tritium.

Whoa! A sensible lunar resource at last. Do you have any source for this?

[Parallax M86]

Whoa! A sensible lunar resource at last. Do you have any source for this?

http://www.lpi.usra.edu/meetings/lpsc2007/pdf/2175.pdf

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-4Y34SV3-1&_user=10&_coverDate=04%2F30%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1398156890&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=7108f9d9ffc67168508eb47b4019f4fe

http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/tx/moonsale/

http://www.technologyreview.com/Energy/19296/

[IsaacKuo]

Helium-3 is not tritium.

[Parallax M86]

Helium-3 is not tritium.

Sorry, I was in a hurry. He-3 is what I meant.

(and yes, my major wasn't in Chemistry :wall:)

[Atraveller]

Seems they might want to use it to go to the Moon. (http://www.bbc.co.uk/news/science-environment-10762634)

The Chinese made unusually open announcements in 2006 that their manned space flight program was intended ultimately to put a base on the moon, and to eventually send a mission to Mars.

This ellicited a response from Bush that NASA was going to go back to the moon and eventually send a mission to mars. (Bush didn't get NASA the money it would need to do any of these things.)

The Chinese have always been very cagey about their programmes, and the US response to thier open announcement was a bit of a shock to them. They have since removed all details of their manned space flight programme from the official web site. CNSA (http://www.cnsa.gov.cn/n615709/cindex.html) atleast from the english version.

[whimsyfree]

Helium-3 is not tritium.

And 3He isn't especially useful for anything on Earth. It's just a myth that is popular because it provides a justification for returning to the moon.

[kamaz]

Sorry, I was in a hurry. He-3 is what I meant.


So, actually not a sensible resource :( Sigh.

[Antice]

The moon has lots of "sensible" resources. The moon comes from the same crucible as the earth did, and the composition is more or less the same.
The problem is the cost of going there to grab it.
Most of the issues with the cost is not just the scale of it. but the fact that so much of it has to be up front before any returns can be expected.
The sheer remoteness of the moon in terms of transport energy and times more or less guarantees that anyone employed to service the lunar facilities are there to stay for extended periods at the least. It would in fact probably be easier to send people there permanently as colonists rather than moving work-shifts back and forth.

[kamaz]

The moon has lots of "sensible" resources. The moon comes from the same crucible as the earth did, and the composition is more or less the same.


This is exactly the problem. The old rule of trade is to exploit a price difference -- find a commodity which is cheap at the location A and expensive at the location B. Buy the commodity at A, move to B, and sell at a profit. The composition of lunar rocks is approximately the same as terrestrial -- which means that there is no price difference. What that means is that the export of raw materials from Moon to Earth is not economical even at negligible transport costs.

The He-3 pipe dream is built on this assumption: find a commodity which is plentiful (cheap) on the Moon but rare (expensive) on Earth. But the problem is that He-3 has no practical applications on Earth, so nobody needs it.

The point is that lunar resources will be of use only on the Moon and in space (due to relatively low lunar gravity).



The sheer remoteness of the moon in terms of transport energy and times more or less guarantees that anyone employed to service the lunar facilities are there to stay for extended periods at the least. It would in fact probably be easier to send people there permanently as colonists rather than moving work-shifts back and forth.

Well, not necessarily. If the transport architecture was based on reusable crafts (see the ULA lunar proposal for example), then there is no point in doing empty runs -- you can shuttle crews back and forth. The key is that you will need large crews (say 100 people) for long shifts (say six months). So assuming everyone on the Moon does 3 2-month turns, you have to shuttle 30-35 people every 2 months (8 weeks). Flight takes 3 days one way, so a shuttle could do one round trip per week. That means (in an extreme case) that one craft carrying 4-5 people on Moon-LEO trip would be enough to provide the crew rotation. Or, use a 35-people craft every two months. (The Earth-LEO part is where it gets harder, though. But something like Skylon would handle that).

I agree however that for destinations like Mars, it would be better to send the crews one way. The energy requirements for round trips are completely ridiculous.