China's Space Program News Thread

[broadsword]

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Constipation is not funny.

 

[Quickie]

I dug the news on this engine a little bit:

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It seems it has 150 tons of propellant in total. The entirety of the engine shouldn't be heavier than 190 tons in total. This means its N.S/kg is around 3090. Insane! For example, the SRB on the new SLS achieves 2780.

Is your calculation based on the engine dry mass as well?

Using the 2500 Ns/kg figure (It can't be /10kg as it would too small.) in #9327, the propellant mass of the engine would have to be 235 ton.

At the reported propellant mass of 150t and 500t, 120s thrust, the impulse would have to be 3920 Ns/kg! which is much more than the 2500 figure.

It is likely that one or more of the reported figures could be off a bit.

 

[Hub]

Is your calculation based on the engine dry mass as well?

Using the 2500 Ns/kg figure (It can't be /10kg as it would too small.) in #9327, the propellant mass of the engine would have to be 235 ton.

At the reported propellant mass of 150t and 500t, 120s thrust, the impulse would have to be 3920 Ns/kg! which is much more than the 2500 figure.

It is likely that one or more of the reported figures could be off a bit.

I think the 2500 is not trustable, but 150/160T, 3.5m diameter and 12m length should be more accurate.

 

[by78]

A newly released old image from Mars, the very last photo taken before solar conjunction.

 

[by78]

The Chinese space station passing over Beijing night sky.

 

[taxiya]

No DF51, because based on China’s naming police, DFAB, A means Number of rocket segments. It’s possible for DF45, not 51

No. "AB" is just numbers in the DF series. There is no segment designation. I believe ICBMs do not use segmented booster at all. You see, SRB is segmented because it is part of the first stage of launch vehicle. ICBMs are three stages, the first stage is much shorter, there is no need for segmentation.

 

[taxiya]

That the engine is referred to as "sharpened sword" also hints at military applications, if there was any doubt.

The thinking should be reversed. Rather than "civilian -> military", it is always "military -> civilian". In essence, when there is civilian application, it is certain that it has been used in military for a long time that the production capacity and cost have dropped to the point to allow civilian usage.

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"Unsheathing sharpened sword" is just a poetic expression, a trend in social media even by the official channels. It doesn't carry any hint.

The technologies in this booster were developed and firstly used in ICBM program. It is now being applied for the "civilian" application.

 

[taxiya]

That's just the engine mass, there's still the mass of the rocket body.

There is no real engine in solid rocket booster in the sense of liquid rocket. The whole thing (casing, propellant and nozzle) is an engine. The 150t is the propellant, leaving 10t for the casing and nozzle.

A solid rocket motor with a carbon fibre body? That just screams ICBM. DF-51?

The technologies were revealed in a 2006 paper in China Aerospace Conference in 2007. At the time it was said to be applied in "future strategic (rocket) motor". By that time all elementary technologies have conducted successful down scale demonstration tests.

DF-41's first test launch was around 2012 or 2013, six years after the subsystems were readily tested. So the timing indicates DF-41 is possibly the "future strategic rocket" in the paper.

The paper listed following techs:

1. Carbon fibre composite first stage. Carbon fibre composite or Aramid fiber second stage. Corbon fibre composite third stage.
2. NB-15 or NB-15B, equivalent to NEPE in performance.
3. C/C composite nozzle.
4. Retractable nozzle.

 

[taxiya]

Is your calculation based on the engine dry mass as well?

Using the 2500 Ns/kg figure (It can't be /10kg as it would too small.) in #9327, the propellant mass of the engine would have to be 235 ton.

At the reported propellant mass of 150t and 500t, 120s thrust, the impulse would have to be 3920 Ns/kg! which is much more than the 2500 figure.

It is likely that one or more of the reported figures could be off a bit.

I think the 2500 is not trustable, but 150/160T, 3.5m diameter and 12m length should be more accurate.

I agree with Hub that only 2500 is questionable. All other figures have been officially posted in text format and relayed by various news outlets meaning multiple chances to eliminate typo errors. The 2500 figure however was only shown in a screen grab and never quoted anywhere else again.

 

[Quickie]

Is your calculation based on the engine dry mass as well?

Using the 2500 Ns/kg figure (It can't be /10kg as it would too small.) in #9327, the propellant mass of the engine would have to be 235 ton.

At the reported propellant mass of 150t and 500t, 120s thrust, the impulse would have to be 3920 Ns/kg! which is much more than the 2500 figure.

It is likely that one or more of the reported figures could be off a bit.

The spokesman was saying 115 secs firing time. So, the impulse should come out to be 3757 Ns/kg.