Chinese 'nauts prep for next coupling in Heaven, clear way for new station China's space agency has announced that its next manned mission will blast off tomorrow - and carry three 'nauts including the programme's second woman space traveller. A Long March 2F lifts Shenzhou 5 at Jiuquan Satellite Launch Centre in 2003 A Long March 2F lifts Shenzhou 5 The Shenzhou-10 craft will take two blokes - …
According to wikipedia, the Long March runs all three stages off nitrous oxide and hydrazine.
I thought that the first stage of spacecraft typically ran off simple fuels like hydrogen/oxygen or kerosene/oxygen. According the _Ignition!_, hydrazine's usually reserved for the upper stages, where its storability is an asset and there aren't any environmental issues to worry about.
I suppose that could make the exhaust look different --- anyone have actual knowledge?
"According the _Ignition!_, hydrazine's usually reserved for the upper stages, where its storability is an asset and there aren't any environmental issues to worry about."
The non cryogenic fuel/oxydizer combination is also welcome in ICBMs, as this allows easy storage and very fast launch...
Furthermore, the environmental issues of those two compound are generally not significant compared to the nuclear warhead. See enclosed picture.
For my money, nothing comes close to the "Star Of Korolev" effect created by the clustered engines of a Soyuz booster ascending.
OK, pseudo-rocket scientist lecture mode on.
You get the diamond effect when the pressure of the exhaust in rocket and jet engines and the ambient atmospheric pressure do not quite match, the terms are under expanded for ambient pressure lower than exhaust and over expanded for ambient pressure higher than exhaust. The effect is actually a supersonic shockwave and you would hear it a crackling in the engine noise (The engine of a Tornado gives a very good example when it's reheat is engaged).
For a rocket engine nozzle this occurs because the shape of the nozzle has to be optimised for the atmosphric pressure it is operating in. For a rocket designed to go from sea level to vaccuum (as Space Shuttle main engine did) it is neccessary to decide which condition the engine is going to spend most of it's operating time and design the nozzle accordingly.
This means that the engine may not be running at it's most efficient at a certain point in it's flight and for the Shuttle this was at launch, as boosters provided much of the impulse to get the vehicle off the ground and through the thickest part of the atmosphere. When these boosters had been used up and jetisoned the main engines were then operating in a high altitude environment that they were most efficient at.
Looking at the Chinese Long March picture I think we see the same kind of thing, a core stage that will fly to quite high altitude and optimised to fly at this lower atmospheric pressure, being supplimented with booster stages which are optimised to work best at ground level to get the vehicle off the pad and to higher altitude.
Right, pseudo- rocket scientist lecture mode off!
I think this is a reasonable explaination of this phenomena but if anyone can add anything to it I would be interested.
Cheers
First, well done to China! Getting a rocket away is difficult and hats should always be lifted when it happens. Technically, the rocket hasn't launched yet but I like to be ahead of the curve, should anything happen then I'll say later that I was being sarcastic.
There is a mystery though. Tiangong-2 is due to launch later this year, all 20,000kg of it. What I've heard seems to be that they're planning to use a regular LM-2F/G with extra strap-ons to get it up there. Anyone got any hard info on that?
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