[MV] Tea under armour

>At 1:49 AM -0400 7/9/04, J. Forster wrote:[color=blue]
> Was this a water-to-water heat exchanger, heated by the engine coolant? =[/color]
Was[color=blue]
>the coolant flow valved, so the water heater could be shut off?[/color]

The early ones were resistive. I'm not sure what=20
the current crop are...The ones for the Ferret,=20
Saracen/Saladin/Stalwart and other bigger AFVs=20
were electric off of the 24 volt. The problem=20
with the ones on the Ferrets was the resistive=20
load could quickly drain the battery so they were=20
all pulled from use. The larger vehicles with=20
more battery power seemed to do ok.

[color=blue][color=green]
> > Post war you started seeing a boiling
>> vessel that would run off vehicle power but was
>> portable away from the vehicle.[/color]
>
>I assume this was electric?[/color]

Initially yes. The US seems to like using fuel=20
fired boiling vessels with all of the associated=20
issues of poisonous gases and such.. I'm not sure=20
what they keep thinking with that...when they add=20
them at all.
[color=blue]
>Electric? If you are going to provide hot food=20
>and drink for the troops, this is
>certainly less muss and fuss than a trioxane=20
>stove. Also, if you are in a CW or
>BW environment, not having to go outside is certainly a plus.[/color]

Yep! It's less time spent doing comfort/survival=20
things by the troops and if you can make hot food=20
while on the move, it's even better for your=20
crews.
[color=blue]
>If you've got waste heat, it could easily be used to distill water. OTOH, t=[/color]
he[color=blue]
>'YUK' factor might be hard to overcome. NASA certainly recycles water on
>spacecraft.[/color]

Give it time. Modern Military engines certainly=20
have lots of waste heat, however, I'm not certain=20
how easy it is to clean such devices...perhaps a=20
disposable distilling element?

When one thinks about it, it seems clear that the=20
brits often have the best ideas when it comes to=20
tanks. After all, they did invent the beasts.
--
--
Ryan Gill [email]rmgill@SPAMmindspring.com[/email]
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_w/|=3D_[__]_=3D \w_ // [_] o[]\\ _oO_\ /_O|_
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|s|\ /|s| |s|/BSV 575\|s| |x|-\| |/-|x|
|s|=3D\______/=3D|s| |s|=3D|_____|=3D|s| |x|--|_____|--|x|
|s| |s| |s| |s| |x| |x|
'60 Daimler Ferret '42 Daimler Dingo '42 Humber MkIV (1/3)
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Ryan Gill wrote:
[color=blue]
> The problem with the ones on the Ferrets was the resistive
> load could quickly drain the battery so they were
> all pulled from use. The larger vehicles with
> more battery power seemed to do ok.[/color]

A typical electric 4 to 6 cup coffee pot or tea kettle draws 1250 to 1500 watts for
5 to 10 minutes. That's 52 to 63 amps at 24 volts, which is a lot to expect of any
battery.

More scientifically: heating water from 20 C to 100 C requires 80 cals/gm = 80
cals/cc. The mechanical equivalent of heat is 4.18 J/cal = 4.18 Watt-Seconds/Cal.
So it takes 80 x 4.18 = 334 W-S/gm The actual power required will be higher.

So to raise 1 cup, roughly 250 cc, of water to the boiling point, it takes 250 x
334 = 83,500 watt-seconds which is roughly 24 Volts @ 1Amp for 1 hour or 24 Volts @
30 Amps for 2 minutes. That's for 1 cup.
[color=blue][color=green][color=darkred]
> > > Post war you started seeing a boiling
> >> vessel that would run off vehicle power but was
> >> portable away from the vehicle.[/color]
> >
> >I assume this was electric?[/color]
>
> Initially yes. The US seems to like using fuel
> fired boiling vessels with all of the associated
> issues of poisonous gases and such.. I'm not sure
> what they keep thinking with that...when they add
> them at all.[/color]

Basically, fuel is a lot more efficient way of storing energy than batteries. I
posted a comparison some weeks ago and a pint of gasoline has about the same energy
content as a car battery a 1/40 or less of the weight.
[color=blue]
> Yep! It's less time spent doing comfort/survival
> things by the troops and if you can make hot food
> while on the move, it's even better for your
> crews.[/color]

True. Also, the IR signature of a vehicle may be lower than a stove in the open.
[color=blue][color=green]
> >If you've got waste heat, it could easily be used to distill water.[/color]
>
> Give it time. Modern Military engines certainly
> have lots of waste heat, however, I'm not certain
> how easy it is to clean such devices...perhaps a
> disposable distilling element?[/color]

If you distill with vacuum at near room temperature, rather than with a heater, the
container with the concentrated and dry or nearly dry waste could be discarded.
IMO, that's what NASA does.
[color=blue]
> When one thinks about it, it seems clear that the
> brits often have the best ideas when it comes to
> tanks. After all, they did invent the beasts.[/color]

Perhaps it's because they follow the dictum that simple is better than complicated.
There are two ways to look at bells and whistles: the optimistic and the cynical
(that's something MORE to go wrong). The Brits seem to tend toward the latter.

-John


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John
[color=blue][color=green]
> > The problem with the ones on the Ferrets was the resistive
> > load could quickly drain the battery so they were
> > all pulled from use. The larger vehicles with
> > more battery power seemed to do ok.[/color]
>
> A typical electric 4 to 6 cup coffee pot or tea kettle draws 1250 to 1500 watts for
> 5 to 10 minutes. That's 52 to 63 amps at 24 volts, which is a lot to expect of any
> battery.[/color]

Your physics are true enough, it was really the intention that the
boiling vessel (kettle) be used whilst the engine was running, rather
than off battery power, a cold weather concept I dare say. But as we
all know, the military dances to its own tune and the idea of
conservation of resources was far less an issue from the 1940s to the
1980s than it is now.
These things were really intended for heavy armour, it was wishfull
thinking to put them in Ferrets. As Andrew Jeffrey has commented in the
past, when he used his BV in his Saracen to make a cuppa, it was the
most expensive cuppa he has ever drank as the electrical load
necesitated running the engine. Petrol isn't cheap in the UK
for civilians.........
[color=blue][color=green]
> > Yep! It's less time spent doing comfort/survival
> > things by the troops and if you can make hot food
> > while on the move, it's even better for your
> > crews.[/color][/color]

If you are in any doubt, ask any US serviceman who has done exchange
time with the Poms. They will soon attest that British armoured
vehicles and their BVs are an extremely popular item with anyone in
the front line. There is a standard signal,
going back to before WW2 where anyone outside an AFV just gives a
couple of raps against the armour with a metal cup etc then hands it
in thru a hatch and after a couple of minutes a crew member will
appear with it full of hot water.
[color=blue][color=green]
> > When one thinks about it, it seems clear that the
> > brits often have the best ideas when it comes to
> > tanks. After all, they did invent the beasts.[/color][/color]

I never have figured out quite what the English are up to with armour.
They seem to be able to make excellent guns, good optics, horrific
engines and tedious levels of maintenance duties that more resemble
pretzel theory than preventative maintenance. But hey, they made
the Ferrets and nobody else has ever even come close to such a good
AFV for us collectors, so we learn its idiosyncrasies and adjust to
them.
[color=blue]
> Perhaps it's because they follow the dictum that simple is better
> than complicated.[/color]

Huh, no way. Go look at the gearbox schematics from any British heavy
AFV from the Matilda onwards. The bloke who designed it went crazy in
the process. It is a puzzle palace to say the least, way ahead of its
time.
[color=blue]
> There are two ways to look at bells and whistles: the optimistic
> and the cynical (that's something MORE to go wrong).
> The Brits seem to tend toward the latter.[/color]

Substitute "WW2 German" engineering in that sentance and I will agree
with you.
The US caught up with the M60 Tank, any tank made in that 1960s era
that requires dedicated mechanics just to keep the turret functioning
due to its complexity has slid out of the optimistic into the
cynical I would say.

Its all rather academic now anyway. It no longer appears to matter
which country makes any of this stuff, it is all hoplessly complicated
and controlled by electronics and way beyond the backyard mechanic if
it goes wrong. You either have the genuine bits to fix it or you don't.

Regards
Doug

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Armoured Vehicles Collector
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/ [___] [___] \ Douglas Greville _/[o]___\_
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M8 Ferret

[email]dgrev@iinet.net.au[/email]

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