
42 feet per gallon - markbnine
http://www.nasa.gov/mission_pages/shuttle/flyout/crawler.html
======
javanix
You know, 42 feet per gallon sounds pretty terrible, but I'd say moving 5.5
_million_ pounds of equipment 42 feet with one gallon of gas is pretty damn
impressive.

~~~
gxti
Put differently, a 30mpg, 4500lb car gets 713e6 feet-pounds/gallon (30m/g *
5280f/m * 4500lb). A loaded crawler gets 756e6 feet-pounds/gallon (42fpg *
18e6 lb). Not so different after all! And the car looks much less attractive
if you look at just the payload.

~~~
gregable
This is a meaningless calculation. It's not as though the amount of energy
required to move something a specific distance is weight related. The amount
of force required to accelerate it to a specific velocity is, but once at that
velocity, energy required is a function of friction. Of course _larger_
objects have more air friction on average, but really what you want is some
measure of the surface area of the object.

Bah, not that it matters in the least.

~~~
oiuyftgrghjk
Interesting comparison.

A container ship does about 24knots = 40feet/second

It uses around 350tons of fuel/day = 4.5 l/s = 1.2USgall/s

So it does a very similar consumption - around 35feet/gallon

While carrying 150,000tons of cargo = 320million pounds.

~~~
xxpor
The low speed (90 rpm) diesels in those ships are by far and away the most
thermally efficient internal combustion engines on the planet. The biggest
ones approach 50% efficient.

[http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...](http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C)

~~~
tocomment
Why is that? Why don't they use these to generate electri ity?

~~~
oiuyftgrghjk
Because external combustion engines (boiler + turbine) are more efficient and
cheaper to build at large scale

~~~
tocomment
So why not use those in ships?

~~~
ramchip
According to this marine engineering book (
[http://books.google.com/books?id=PCSpWWuTgkkC&lpg=PA53&#...</a> ) and this
website ( <a
href="http://library.fentu.ru/book/gumi/101/English/section_1_main_marine_engines.html"
rel="nofollow">http://library.fentu.ru/book/gumi/101/English/section_1_main...</a>
) which seems based on the book, slow diesel engines are more efficient, but
turbines <i>are</i> used in ships.<p><i>The steam turbine has until recently
been the first choice for very large power main propulsion units. Its
advantages of little or no vibration, low weight, minimum space requirements
and low maintenance costs are considerable. In steam turbines high pressure
steam is directed into a series of blades or vanes attached to a shaft,
causing it to rotate. This rotary motion is transferred to the propeller shaft
by gears. Steam is produced by boiling water in a boiler, which is fired by
oil. Recent developments in steam turbines which have reduced fuel consumption
and raised power output have made them more attractive as an alternative to
diesel power in ships. They are 50 per cent lighter and on very large tankers
some of the steam can be used to drive the large cargo oil pumps. Turbines are
often used in container ships, which travel at high speeds.</i>

------
rue
So, 12,8m/3,78541178l or EU standard combined: 29573,53l/100km?

I wish at least sciency articles used SI.

~~~
axod
The numbers you just put above mean nothing to me. Feet per Gallon is
something humans can visualize.

I'm sure I'll get downmodded to hell for expressing this opinion here, but I
really do prefer imperial measurements.

~~~
jmillikin
It's only something you can visualise if you grew up with imperial units; "42
feet per gallon" is not inherently easier than "3.4 meters per liter", nor
"125.7 gallons per mile" than "296 liters per km".

~~~
wtallis
But all of those are far more accessible than 29573.53L/100km, which most
people would just round up to "a hell of a lot". Using conventional units
doesn't really help when the magnitude is so high.

~~~
pmjordan
30000 litres is the same as 30 cubic metres, i.e. "small swimming pool". Easy.

------
Nick_C
Mike Rowe of _Dirty Jobs_ got to drive the crawler in one episode. It was a
cool episode. You appreciate just how big it is when you see him standing next
to the treads.

------
ck2
Article doesn't say how far it typically has to travel.

Traveling quarter mile, no big deal. Traveling 10 miles, much more expensive.

~~~
drv
Seems to be about 3 miles from most of the launch pads to the VAB, so about
377 gallons for a one-way trip (<http://www-
pao.ksc.nasa.gov/nasafact/count3teaf.htm>)

The crawler can travel about 1 MPH loaded; the tour guide at KSC (at least
when I was there several years ago) made a big deal about the blazing 2 MPH it
can do when unloaded. :)

~~~
spc476
The closest observation point is three miles from the launch pads, so yes, the
VAB (Vehicle Assembly Building; it's insanely large) is probably around three
miles as well.

Why the three mile distance? Back during the Apollo program, engineers
determined that if the Saturn V were to explode on the launch pad, the
resulting fireball would be around four or file miles in diameter. I think
it's a similar radius for the Shuttle as well.

~~~
snth
So the fireball would still engulf the buildings? Doesn't that still seem too
close?

~~~
kylemathews
Diameter not radius.

So 4-5 miles diameter = 2-2.5 miles radius.

