Tuesday, July 26, 2005

Soviet Orion to Luna to L5 Fuel costs

Rough notes for calculations- to be cleaned up


2.127 The size of the fireball increases with the energy yield of the explosion. Because of the complex interaction of hydrodynamic and radiation factors, the radius of the fireball at the thermal minimum is not very different for air and surface bursts of the same yield. The relationship between the average radius and the yield is then given approximately by

R (at thermal minimum) » 90 W0.4

where R is the fireball radius in feet and W is the explosion yield in kilotons TNT equivalent. The breakaway phenomenon, on the other hand, is determined almost entirely by hydrodynamic considerations, so that a distinction should be made between air and surface bursts. For an air burst the radius of the fireball is given by

R (at breakaway) for air burst » 110 W0.4, (2.127.1)

For a contact surface burst, i.e., in which the exploding weapon is actually on the surface,[8] blast wave energy is reflected back from the surface into the fireball (§ 3.34) and W in equation (2.127.1) should probably be replaced by 2 W, where W is the actual yield. Hence, for a contact surface burst,

R (at breakaway) for contact surface burst » 145 W0.4. (2.127.2)

For surface bursts in the transition range between air bursts and contact bursts, the radius of the fireball at breakaway is somewhere between the values given by equations (2.127.1) and (2.127.2). The size of the fireball is not well defined in its later stages, but as a rough approximation the maximum radius may be taken to be about twice that at the time of breakaway (cf. Fig. 2.121).

2.128 Related to the fireball size is the question of the height of burst at which early (or local) fallout ceases to be a serious problem. As a guide, it may be stated that this is very roughly related to the weapon yield by

H (maximum for local fallout) » 180 W0.4 (2.128.1)

where H feet is the maximum value of the height of burst for which there will be appreciable local fallout. This expression is plotted in Fig. 2.128. For an explosion of 1,000 kilotons, i.e., 1 megaton yield, it can be found from Fig. 2.128 or equation (2.128.1) that significant local fallout is probable for heights of burst less than about 2,900 feet. It should be emphasized that the heights of burst estimated in this manner are approximations only, with probable errors of +30 percent. Furthermore, it must not be assumed that if the burst height exceeds the value given by equation (2.128.1) there will definitely be no local fallout. The amount, if any, maybe expected, however, to be small enough to be tolerable under emergency conditions.


From: David Johnson - Find messages by this author
Date: Tue, 26 Jul 2005 18:08:29 GMT
Subject: Re: The Soviet O'Neill Habitats
"bombardmentforce" wrote in

> Derek Lyons wrote:
>> Luke7...@aol.com wrote:

>> >Well, yes. But I think we'd have to be rather further back than that.
>> >Hauling up the various bits and peices to build an O'Neill habitat
>> >would be really, really pricey via OTL's rocket tech.

>> That's mostly because OTL has never spent any real attention to
>> decreasing costs. The current (high) costs are an artifact of
>> history, not a certainty.

>> >Hence, the appeal of Orion.

>> An Orion isn't really much cheaper than an ordinary rocket in OTL.
>> Nuclear weapons (excuse me, "plasma pulse units") are expensive little
>> beasties.

>> D.

> Care to elaborate? Expensive per what energy unit?

> "Hydrogen bombs are the only way to burn the cheapest fuel we have,
> deuterium."
> "...fuel cost for deuterium is about .0003(1968) cent per kilowatt
> hour."
> Freeman Dyson - Interstellar Transport - Physics Today October 1968

Actual cost of _fuel_ (unless you're talking about something ridiculously
exotic) has always been the tiniest percentage of the total cost of a
launch. Yes, deuterium is pretty cheap on a money per unit of energy
basis. And if that was it, you might save, oh, a few hundred thousand
dollars per launch over using Kerosene & LOX (out of tens or hundreds of
millions of total launch costs). On that basis, _fuel_ costs into orbit
would probably be about the same as gas costs to drive from L.A. to
Phoenix and your cost per pound into orbit drops from a tiny, tiny bit.

Current costs per pound to LEO are around $2,000-$5,000 per pound. Of
that, about _$10_ a pound is the fuel costs (for kerosene/LOX). From a
fuel-costs standpoint - even if the deutronium is _free_ - you've saved
at most one-half of a percent of the total launch costs. This may not be
worth it...

...now also remember that to _use_ that deuterium in an Orion, you have
to build it into a very expensive, technologically tricky bomb...lots and
_lots_ of very expensive, technologically tricky bombs. Imagine your gas
costs on that Phoenix trip if the gasoline was built in to an engine -
and you had to replace that engine every mile.

Orion works pretty much like that.


90$(1997) per WU

http://groups-beta.google.com/group/soc.history.what-if/msg/31b024b78b69cf79?hl=en&Derek Lyons Jul 26, 1:40 pm show options
Newsgroups: soc.history.what-if, rec.arts.sf.science
From: fairwa...@gmail.com (Derek Lyons) - Find messages by this author
Date: Tue, 26 Jul 2005 17:40:05 GMT
Local: Tues,Jul 26 2005 1:40 pm
Subject: Re: The Soviet O'Neill Habitats

"bombardmentforce" wrote:
>Derek Lyons wrote:
>> An Orion isn't really much cheaper than an ordinary rocket in OTL.
>> Nuclear weapons (excuse me, "plasma pulse units") are expensive little
>> beasties.

>Care to elaborate? Expensive per what energy unit?

>"Hydrogen bombs are the only way to burn the cheapest fuel we have,
>deuterium." "...fuel cost for deuterium is about .0003(1968) cent per
>kilowatt hour."
>Freeman Dyson - Interstellar Transport - Physics Today October 1968

It takes a good deal (kilograms) of the *most* expensive fuel we have
(supergrade uranium and plutonium) to burn a trivial amount (grams) of
the 'cheapest' fuel. Dyson predicated Orion's low cost on something
that has never materialized (despite an intensive search) - light,
cheap hydrogen weapons that didn't use fission to initiate fusion.


w74 452,000 $1973 canceled
w75 400,000 $1973
w82 4,000,000 $1982 2kt 43 kg n
w84 1,100,000 $1981
w80-1 720,000 $1990

Between 1956 and 1963, 2,100 were produced at an estimated cost
(excluding the warhead) of $540 million (in constant 1996 dollars).
257,000 each



$165 billion from 1948 to 1995) associated with the production of
nuclear weapons materials (highly-enriched uranium, plutonium and

13. Fissile material produced: 104 metric tons of
plutonium and 994 metric tons of highly-enriched

6. Total number and types of nuclear warheads and bombs built,
1945-1990: more than 70,000/65 types

Tritium Cost Per gram 23,000
LiD6 $ Per Kg 15,000
LiD7 $ Per Kg 1,500
Reactor PU $/Kg 5,000

Mega Joules / KT 4,120,000
h2+o2 MJ /Kg 6.67

0.3 $/KG Jet A
2 $/KG H2
15000 $/ Kg Li(6) D
50000 $/ Kg (BG) Pu


150 Kilotons
4,600,000 $
30666.66667 $/KT
30.66666667 $/Ton
4.12E+12 Joules / KT
6.18E+14 Joules / Blast
7.44337E-09 $/ Joule
0.007443366 $/ Megajoule
26.7961165 $/ Megajoule Hour

Isp =144 sqrt(heat in Kj/mol/mass of propellant g/mol)


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