Newsgroup: it.cultura.storia.militare
Titolo: alcune stime


Those figures are reasonable.  According to "China Built The Bomb"
(a book published in U.S. during the late-1980's), data from various
U.S. intelligence agencies showed that, in the mid-1980's, China was
producing at least 800 kilograms of U-235 and 400 kilograms of Pu-239
per year:
 1). Lanzhou Gaseous Diffusion Plant      400kg U-235/year
 2). Helanshan Centrifuge I               400kg U-235/year
 3). Helanshan Centrifuge II              ???
 4). Yumen Breeder Reactor                250kg Pu-239/year
 5). Baotou Breeder Reactor               150kg Pu-239/year
 6). Guangyuan Breeder Reactor            ???
A typical fission-only nuclear device (N-bomb) in U.S. and Russian
nuclear arsenals uses an averge of 15 kilograms of U-235 or 5 kilograms
of Pu-239, with a typical yield in tens of kiloton TNT.
In fact, a fission nuclear device can be built with just 1.8 kilogram
of Pu-239 by using the neutron reflection/multiplying technique with
U-238/Beryllium tamper in addition to the normal implosion technique,
but the yield will be barely kiloton TNT or ever sub-kiloton TNT.
However, this will be enough as the fission trigger in the thermonuclear
device (the so-called "Hydrogen-bomb").
Except the fission-trigger, the thermonuclear device could be built
without the additional U-235/Pu-239, just the Lithium6-Deuteride
fusion core plus the U-238 pusher and U-238 jacket in the normal
fission-fusion-fission H-bomb, or the fusion core with the Tungsten
pusher and jacket in the fission-fusion Neutron-bomb.
Given the amount of fissionable material (U-235/Pu-239) being produced,
it is very likely that China is making 140-150 nuclear warheads every
year and has accumulated 2,350 nuclear warheads.  However, those are
just a tiny fraction compared to 30,000+ nuclear warheads each in U.S.
or Russian nuclear arsenal.  Even if the START-II Treaty is implemented
by 2010, there will still be more than 20,000 nuclear warheads each in
U.S. or Russian nuclear arsenal.  So China will never be able to acquire
even a comparable level of nuclear arsenal to U.S.'s or Russia's.
In the discussion about the U.S. military involvement in the Taiwan
Strait recently, someone shouted "we should nuke the Chinamen/Chinks"
and "we don't have to worry about China's nuclear weapons since they
can only reach Hawaii and maybe California".  What a callous ignorant
blood-thirsty racist (he's on the eastern coast)!
China does have ICBMs which can reach virtually every corner of every
nuclear power: the SS18-class DF-5 with a range of 8000 miles.  It has
the identical boosters (CZ-2C) used in launching Chinese spy satellites
which has a launch success rate of 100% (no failure out of 18 launches).
The failed satellite launch in February used a different CZ-3B rocket
with 4 strapped-on liquid boosters (the February launch was the first
flight of CZ-3B).
China's DF-5 ICBM entered into the service in 1980 after the extensive
flight tests (at least 5 in 1979).  According to the Jane's Strategic
Weapons, its throw weight is said to be 3200kg, which I think is much
lower than its actual capacity.
(The Jane's Strategic Weapons yearbook had been giving totally wrong
 specifications of Chinese missiles until 1991, while China published
 the complete specifications of CZ-2/3 rocket series in 1985, which
 was used in the Jane's Spaceflight Directory.  I think the editors
 of Jane's Strategic Weapons are good only at creating rumors about
 China's missile sale.  They may have certain motives in doing so,
 I'll deliberate this later).
According to the Jane's Spaceflight Directory, the 1st-generation
Chinese spy satellites (FSW-1) weighs about 2500kg, which is launched
by the same CZ-2C booster (as in the DF-5 ICBM) into the LEO.  This is
quite accurate as China offered to launch the international satellite
of 2000kg with the CZ-2C booster.  The 500kg difference is due to the
fairing/shroud used to protect the satellite from the aerodynamic force
during the launch (the FSW-1 spy satellite is recoverable and thus its
body is hardened for the atmosphere reentry, so no extra fairing/shroud
is needed during the launch).  As a comparison, the French Ariane-4 has
a longer and wider fairing/shroud weighing 900kg and a 520kg vehicle
equipment bay (VEB) for the flight control and guidance.
It is reasonable to assume that the CZ-2C's vehicle equipment bay
weighs at least 500kg.  Together with the 4000kg dry weight of CZ-2C
second stage rocket motors, at least 7000kg of satellite+VEB+motor
is accellerated to the 7900m/sec burnout speed needed for the satellite
launch into the LEO.
For an 8000-mile-range ICBM, the burnout speed is about 7200m/sec.
Since the specific impulse of the CZ-2C 2nd-stage rocket motor YF-22
is rated at 295 second (lower for the venier motor YF-23), for a delta
V of 700m/sec (7900-7200), it takes just the high school calculus to
determine that the CZ-2C booster can accelerate at least 8900kg to
the burnout speed of 7200m/sec, an 1900kg increase in the payload.
Therefore the 8000-mile DF-5 ICBM should have a throw weight of at
least 4400kg (2500+1900) for the warhead, in which you could put
put a 10-megaton thermonuclear device (such as the one on SS-19)
easily (China's Lop Nor nuclear test site won't be able to handle
such a monster, probably having to use just scale-up for design).
In the same Jane's Spaceflight Directory, China offered to launch
4 satellites on one CZ-2C.  This means its twin DF-5 is also MIRV-
capable (after all, MIRV is not the hi-tech, just weight-balancing
and proper-timing of warhead-releasing, if Russia can develop it
in 1960's, China should have no problems to develop it in 1980's).
In fact, the DF-5 was probably designed with the MIRV in the mind
since the CZ-2C's second-stage has 4 venier motors for steering
and they continue to burn for further 190 seconds after the main
motor shutoff (this could produce a LARGE footprint for MIRVs).
For the MIRV-version of DF-5, its throw weight should be reduced
to 3900kg as the fairing/shroud is needed to protect the MIRVs.
So it's very likely that DF-5 is carrying six 600kg-weight warheads
as on the DF-21 IRBM (the twin of JL-1 SLBM).  The warhead size (about
1.9m x 0.9m) is right for fitting six in the CZ-2C/DF-5 fairing/shroud.
I think the Jane's Strategic Weapons is wrong again on the yield
of DF-21 warhead (it says 250-kiloton). The JL-1/DF-21 entered into
the services in 1982 and all of China's nuclear tests before 1983
are on the two extreme ends: either 10-50 kiloton (fission weapons)
or 1-4 megaton (thermonuclear devices).  It was until 1990 that China
conducted a nuclear test in the 200 kiloton range.  By the common sense,
it's very unlikely that China would put a 250-kiloton warhead on DF-21
without testing it back then (there was not single political/technical
restriction on testing a medium-yield warhead).
I think the 600kg warhead on DF-21 is an 1-megaton thermonuclear
device given the shape and density of the warhead on the picture.
As a comparison, the W-47 RV on the U.S. Polaris A-1 SLBM (1961)
weighs 408kg and has a yield of 800-kiloton; the bomb itself weighs
only 275kg.
So the 8000-mile DF-5 ICBM is probably carrying six(6) 1-megaton MIRVs.
Now the question is: how many does China have?
The number of DF-5s quoted in various publications are always the same
number throughout the decade: only four(4) DF-5 ICBMs in silo.  Does
anyone ever use the common sense: China conducted AT LEAST seven(7)
flight tests of DF-5 in 1979-1980 alone, why deploying only four(4)?
There is a photo on Page 239 of the 1992 Jane's Spaceflight Directory,
which shows the final assembly workshop for the CZ-2C/DF-5.  In the
photo, there are about nine(9) CZ-2C/DF-5 in the various phases of
final assembly and the text states that the production rate is about
10--12 per year (does it really take 9 months to put ONE rocket through
the final assembly line???  After all, the liquid-fueled rocket is just
some aluminum tanks connected with pipelines and combustion chambers).
It has been fifteen(15) years since the DF-5 entered into the services,
during which China was mostly under the threat of a Soviet invasion
(the other Chinese missiles could not reach Soviet European region).
During the period, there are no more than 30 satellite launches by
China.  So there could be between 120 and 150 DF-5 ICBMs in the
Chinese arsenals.  With six 1-megaton warheads on each of them,
700-900 out of 1800 so-called strategic warheads are counted.
Now the question is: where are those DF-5 ICBMs?
I think the answer lays in the PLA's bible: the Art of War written
by the famous military strategist SUN Zi 2300 years ago.  One of its
mottos is: if you can not win a battle, do NOT fight it.
China knows that the silos can be easily located by satellites and
its early-warning systems are too primitive, and the launch-on-warning
could be very dangerous (despite the popular belief in the newsgroups,
all China's liquid-fueled SSMs are using the same storable propellants
as in SS-18), plus that silo-hardening is just a losing battle and its
nuclear submarine technology is generations behind superpowers.
So China avoids the very vulnerable silo basing deployment of
strategic ballistic missiles and hides them inside underground
tunnels/caves in deep canyons/mountains.  Those missiles are
prepared inside the caves and moved outside to launch.  In addition,
the Command-and-Control will be much easier to maintain for this
kind of deployment.
Early 1995, China's media reported that a so-called "Great Wall"
project for the strategic missile force has been completed after
10 years of construction in a "famous" mountain range in North China.
Look at the topographic maps and read the news reports carefully,
it can be deduced that the underground tunnel network is in the famous
Tai-Hai Mountain Range between Hebei and Shanxi provinces.  According
to the news reports, "tens of thousands" of Army engineers have spent
over 10 years there digging tunnels.
Normally, a company of soldiers (about 100+) can dig about 100 meter
of tunnel per month (based on the news reports about railroad tunnel
construction) without using any advanced tunnel drilling machinery.
So the "tens of thousands" of Army engineers (= hundreds of companies)
over the 10-year period should be able to construct an underground
tunnel network of thousands of kilometers(!!!) inside the Tai-Hei
Mountain Range to hide some of China's strategic missiles.  I guess
it was called the "Great Wall" project not without a reason (the Great
Wall is at least 5000 kilometers long).
Like other known mountain ranges housing the underground tunnel
networks for China's strategic missiles, the Tai-Hei Mountain Range
has a lot of steep cliffs/canyons with very big elevation change
over a short distance (between 1000 meters and up to 2000 meters).
So you can easily dig tunnel networks with over one kilometer thick
of earth cover in mountain ranges.
A typical 500-kiloton nuclear warhead in U.S. or Russian arsenals
can `dig' a big hole (70m deep and 300m wide) on the ground, and
that's more than enough to destroy a missile silo or even an airport.
If specially hardened for the earth-penetration purpose, it may
create a huge crater sphere 200m in diameter underground.  Taken into
account of the rupture zone around the crater and the likely penetration
depth of warheads, AT LEAST three 500-kiloton warheads will have to
land on the same spot sequentially in order to penetrate the 1-kilometer
thick earth cover and destroy the tunnel underneath.  Even with the
monster 20-megeton warhead on the Russia's single-warheaded SS-18, you
will still have to have two warheads landed on the same spot.
However, you just destroy less than 300 meter length of tunnel
using three warheads.  If the underground tunnel network under the
Tai-Hei Mountain Range is just 1000 kilometer long, you need to use
10,000 (ten thousand) 500-kiloton warheads in order to make sure
the tunnel network is completely destroyed, and this is the VERY
unlikely case in which you know the exact layout of entire tunnel
network.  AND this is just one of several missile sites.

 molto interesse mentre qua propbabilmente nessuno si interesserà...
Forse è per via di quel prefisso SCI, perché se fosse HIST probabilmente
sarebbe giudicato OT proprio come qui.
Ma non è detto che non interessi a nessuno, come *complemento* alla storia
militare. Il problema è che appunto dev'essere un complemento e non il
topic del gruppo. Hai ragione quando dici che hai difficoltà a trovare un
ambiente che si interessi _principalmente_ di queste tematiche, ma non ci
può far niente nessuno se in italiano non esiste...
C'è la stessa differenza che corre tra la fisica e l'epistemologia: se il
topic è l'epistemologia, è inutile aspettarsi rivelazioni sugli ultimi
progressi nel campo della struttura dell'atomo, e d'altra parte non è
detto che un valente fisico delle particelle sia interessato ANCHE  alla
storia e alla filosofia della scienza.
Perché non cerchi di proporre al GCN un nuovo gruppo dedicato alla
tecnologia militare (
p.es
.:  it. scienza.militare)? Lo voterebbero tutti,
qui!
Anche se ho il sospetto che lo farebbero per sbarazzarsi di te ;-))
saluti
--
Piero F.
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(email: togliere xyz dall'indirizzo)

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A me sembra che alla fine questo ng non sia poi così frequentato (vi saranno
si e no una cinquantina di nuovi post al giorno) e che magari supportando
degnamente anche discussioni riguardo la tecnologia militare (il che
comunque interesserebbe a molti) il numero dei frequentanti e dei post
aumenterebbe senza troppo nuocere ai napoleonici ecc... Naturalmente questa
è la mia personale idea. Dopotutto nel manifesto del gruppo si fa menzione
esplicita che gli armamenti sono IT. Inoltre anche la guerra fredda ad
esempio fa ampiamente parte della storia militare.