Hi all.

These days the word 'rocket' is used to denote a flying
missile, propelled by the rapid intrenal burning of some
fuel, where the expelled exhaust gases provide the driving
force.

Some 200 years ago, Stephenson's first viable railroad
locomotive, powered by a steam engine, was named
'The Rocket.'

So I am wondering if the term 'rocket' meant something
else at that time? Or were rockets, in the presently
accepted meaning of the term, known at the time?

Rune

Rune Allnor wrote:
> Hi all.
>
> These days the word 'rocket' is used to denote a flying
> missile, propelled by the rapid intrenal burning of some
> fuel, where the expelled exhaust gases provide the driving
> force.
>
> Some 200 years ago, Stephenson's first viable railroad
> locomotive, powered by a steam engine, was named
> 'The Rocket.'
>
> So I am wondering if the term 'rocket' meant something
> else at that time? Or were rockets, in the presently
> accepted meaning of the term, known at the time?
>
> Rune


The Mongols had used rockets in the late middle ages*  in
assaulting European places, so I imagine his use
of the word is simply to imply "fast".

*1200s.

--
Les Cargill

http://www.etymonline.com/index.php?term=rocket

rocket (2)
    "projectile," 1610s, from It. rocchetto "a rocket," lit. "a bobbin," dim. of
rocca "a distaff," so called because of cylindrical shape. The Italian word
probably is from a Germanic source (cf. O.H.G. rocko "distaff," O.N. rokkr),
from P.Gmc. *rukka-, from PIE base *rug- "to spin." Originally "fireworks
rocket," meaning "device propelled by a rocket engine" first recorded 1919;
rocket-ship first attested 1927. The verb meaning "to spring like a rocket" is
from 1883. Rocket science in the figurative sense of �difficult, complex process
or topic� is attested by 1985. Rocket scientist is from 1952.

I think the need for external oxygen also comes into play...

Mark

On 10/12/2011 15:44, Greg Berchin wrote:
> http://www.etymonline.com/index.php?term=rocket
>
> rocket (2)
>      "projectile," 1610s, from It. rocchetto "a rocket," lit. "a bobbin," dim. of
> rocca "a distaff," so called because of cylindrical shape. The Italian word
> probably is from a Germanic source (cf. O.H.G. rocko "distaff," O.N. rokkr),
> from P.Gmc. *rukka-, from PIE base *rug- "to spin." Originally "fireworks
> rocket," meaning "device propelled by a rocket engine" first recorded 1919;
> rocket-ship first attested 1927. The verb meaning "to spring like a rocket" is
> from 1883. Rocket science in the figurative sense of �difficult, complex process
> or topic� is attested by 1985. Rocket scientist is from 1952.


The OED has it from 1611 in English, to signify the firework. The word 
existed long before with other meanings (including the salad plant). 
Fireworks were of course brought back, along with the gunpowder they 
involved, from China and widely used, especially for grand celebrations 
(hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists 
probably got involved too, one way and another. According to the OED, 
the name "rocket" included squibs and other pyrotechnics, as well as 
rockets fired into the sky. The composer Stamitz (mid-18th Century) 
gained considerable fame composing symphonies for the orchestra at 
Mannheim including dramatic upward-rushing scale figures, popularly 
known thereafter as the "Mannheim Skyrocket". So we may surmise that the 
name was chosen by Stevenson as evoking an image of speed along with 
magic, shock and awe, plus no doubt the literal internal combustion 
aspect too.

Richard Dobson

On 12/10/2011 12:53 PM, Richard Dobson wrote:
> On 10/12/2011 15:44, Greg Berchin wrote:
>> http://www.etymonline.com/index.php?term=rocket
>>
>> rocket (2)
>> "projectile," 1610s, from It. rocchetto "a rocket," lit. "a bobbin,"
>> dim. of
>> rocca "a distaff," so called because of cylindrical shape. The Italian
>> word
>> probably is from a Germanic source (cf. O.H.G. rocko "distaff," O.N.
>> rokkr),
>> from P.Gmc. *rukka-, from PIE base *rug- "to spin." Originally "fireworks
>> rocket," meaning "device propelled by a rocket engine" first recorded
>> 1919;
>> rocket-ship first attested 1927. The verb meaning "to spring like a
>> rocket" is
>> from 1883. Rocket science in the figurative sense of �difficult,
>> complex process
>> or topic� is attested by 1985. Rocket scientist is from 1952.
>
>
> The OED has it from 1611 in English, to signify the firework. The word
> existed long before with other meanings (including the salad plant).
> Fireworks were of course brought back, along with the gunpowder they
> involved, from China and widely used, especially for grand celebrations
> (hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists
> probably got involved too, one way and another. According to the OED,
> the name "rocket" included squibs and other pyrotechnics, as well as
> rockets fired into the sky. The composer Stamitz (mid-18th Century)
> gained considerable fame composing symphonies for the orchestra at
> Mannheim including dramatic upward-rushing scale figures, popularly
> known thereafter as the "Mannheim Skyrocket". So we may surmise that the
> name was chosen by Stevenson as evoking an image of speed along with
> magic, shock and awe, plus no doubt the literal internal combustion
> aspect too.

Tut tut, Richard! Stephenson's Rocket had a boiler, as I'm sureyou know.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On Sat, 10 Dec 2011 13:20:28 -0500, Jerry Avins <jya@ieee.org> wrote:

>On 12/10/2011 12:53 PM, Richard Dobson wrote:
>> On 10/12/2011 15:44, Greg Berchin wrote:
>>> http://www.etymonline.com/index.php?term=rocket
>>>
>>> rocket (2)
>>> "projectile," 1610s, from It. rocchetto "a rocket," lit. "a bobbin,"
>>> dim. of
>>> rocca "a distaff," so called because of cylindrical shape. The Italian
>>> word
>>> probably is from a Germanic source (cf. O.H.G. rocko "distaff," O.N.
>>> rokkr),
>>> from P.Gmc. *rukka-, from PIE base *rug- "to spin." Originally "fireworks
>>> rocket," meaning "device propelled by a rocket engine" first recorded
>>> 1919;
>>> rocket-ship first attested 1927. The verb meaning "to spring like a
>>> rocket" is
>>> from 1883. Rocket science in the figurative sense of �difficult,
>>> complex process
>>> or topic� is attested by 1985. Rocket scientist is from 1952.
>>
>>
>> The OED has it from 1611 in English, to signify the firework. The word
>> existed long before with other meanings (including the salad plant).
>> Fireworks were of course brought back, along with the gunpowder they
>> involved, from China and widely used, especially for grand celebrations
>> (hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists
>> probably got involved too, one way and another. According to the OED,
>> the name "rocket" included squibs and other pyrotechnics, as well as
>> rockets fired into the sky. The composer Stamitz (mid-18th Century)
>> gained considerable fame composing symphonies for the orchestra at
>> Mannheim including dramatic upward-rushing scale figures, popularly
>> known thereafter as the "Mannheim Skyrocket". So we may surmise that the
>> name was chosen by Stevenson as evoking an image of speed along with
>> magic, shock and awe, plus no doubt the literal internal combustion
>> aspect too.
>
>Tut tut, Richard! Stephenson's Rocket had a boiler, as I'm sureyou know.
>
>Jerry

Yes, so I always just assumed the metaphoric moniker was to imply that
it was fast.   Oldsmobile did the same thing in the '50s, as have many
other marketers of things that they wanted to imply performed
admirably.


Eric Jacobsen
Anchor Hill Communications
www.anchorhill.com

On 10 Des, 20:12, eric.jacob...@ieee.org (Eric Jacobsen) wrote:
> On Sat, 10 Dec 2011 13:20:28 -0500, Jerry Avins <j...@ieee.org> wrote:
> >On 12/10/2011 12:53 PM, Richard Dobson wrote:
> >> On 10/12/2011 15:44, Greg Berchin wrote:
> >>>http://www.etymonline.com/index.php?term=3Drocket
>
> >>> rocket (2)
> >>> "projectile," 1610s, from It. rocchetto "a rocket," lit. "a bobbin,"
> >>> dim. of
> >>> rocca "a distaff," so called because of cylindrical shape. The Italia=
n
> >>> word
> >>> probably is from a Germanic source (cf. O.H.G. rocko "distaff," O.N.
> >>> rokkr),
> >>> from P.Gmc. *rukka-, from PIE base *rug- "to spin." Originally "firew=
orks
> >>> rocket," meaning "device propelled by a rocket engine" first recorded
> >>> 1919;
> >>> rocket-ship first attested 1927. The verb meaning "to spring like a
> >>> rocket" is
> >>> from 1883. Rocket science in the figurative sense of =93difficult,
> >>> complex process
> >>> or topic=94 is attested by 1985. Rocket scientist is from 1952.
>
> >> The OED has it from 1611 in English, to signify the firework. The word
> >> existed long before with other meanings (including the salad plant).
> >> Fireworks were of course brought back, along with the gunpowder they
> >> involved, from China and widely used, especially for grand celebration=
s
> >> (hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists
> >> probably got involved too, one way and another. According to the OED,
> >> the name "rocket" included squibs and other pyrotechnics, as well as
> >> rockets fired into the sky. The composer Stamitz (mid-18th Century)
> >> gained considerable fame composing symphonies for the orchestra at
> >> Mannheim including dramatic upward-rushing scale figures, popularly
> >> known thereafter as the "Mannheim Skyrocket". So we may surmise that t=
he
> >> name was chosen by Stevenson as evoking an image of speed along with
> >> magic, shock and awe, plus no doubt the literal internal combustion
> >> aspect too.
>
> >Tut tut, Richard! Stephenson's Rocket had a boiler, as I'm sureyou know.
>
> >Jerry
>
> Yes, so I always just assumed the metaphoric moniker was to imply that
> it was fast. =A0 Oldsmobile did the same thing in the '50s, as have many
> other marketers of things that they wanted to imply performed
> admirably.

Sure, but by that time the term had already gotten its
present meaning: Goddard made his first rockets in the '20s,
while von Braun & Co had lobbed their V2s out of Peenemunde
during WWII.

Rune

On Dec 11, 4:22=A0am, Rune Allnor <all...@tele.ntnu.no> wrote:
> Hi all.
>
> These days the word 'rocket' is used to denote a flying
> missile, propelled by the rapid intrenal burning of some
> fuel, where the expelled exhaust gases provide the driving
> force.
>
> Some 200years ago, Stephenson's first viable railroad
> locomotive, powered by a steam engine, was named
> 'The Rocket.'
>
> So I am wondering if the term 'rocket' meant something
> else at that time? Or were rockets, in the presently
> accepted meaning of the term, known at the time?
>
> Rune

It's a kind of green used in salads.

On 12/10/2011 2:16 PM, Rune Allnor wrote:
> On 10 Des, 20:12, eric.jacob...@ieee.org (Eric Jacobsen) wrote:

   ...

>> Yes, so I always just assumed the metaphoric moniker was to imply that
>> it was fast.   Oldsmobile did the same thing in the '50s, as have many
>> other marketers of things that they wanted to imply performed
>> admirably.
>
> Sure, but by that time the term had already gotten its
> present meaning: Goddard made his first rockets in the '20s,
> while von Braun&  Co had lobbed their V2s out of Peenemunde
> during WWII.

Congreve's rockets were used in war by the British as early as 1810. 
They were refinements of Oriental war rockets, "fire arrows", hundreds 
of years older. http://en.wikipedia.org/wiki/History_of_rockets. Genghis 
Kahn used rockets in his Russian campaign.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On 10/12/2011 18:20, Jerry Avins wrote:
...
>> The OED has it from 1611 in English, to signify the firework. The word
>> existed long before with other meanings (including the salad plant).
>> Fireworks were of course brought back, along with the gunpowder they
>> involved, from China and widely used, especially for grand celebrations
>> (hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists
>> probably got involved too, one way and another. According to the OED,
>> the name "rocket" included squibs and other pyrotechnics, as well as
>> rockets fired into the sky. The composer Stamitz (mid-18th Century)
>> gained considerable fame composing symphonies for the orchestra at
>> Mannheim including dramatic upward-rushing scale figures, popularly
>> known thereafter as the "Mannheim Skyrocket". So we may surmise that the
>> name was chosen by Stevenson as evoking an image of speed along with
>> magic, shock and awe, plus no doubt the literal internal combustion
>> aspect too.
>
> Tut tut, Richard! Stephenson's Rocket had a boiler, as I'm sureyou know.
>
> Jerry

Well yes, but it was burning ~something~, in a firebox, sort of 
internally...did you think I meant petrol? :-)

Richard Dobson

On 10 Des, 20:35, HardySpicer <gyansor...@gmail.com> wrote:
> On Dec 11, 4:22=A0am, Rune Allnor <all...@tele.ntnu.no> wrote:
>
>
>
>
>
> > Hi all.
>
> > These days the word 'rocket' is used to denote a flying
> > missile, propelled by the rapid intrenal burning of some
> > fuel, where the expelled exhaust gases provide the driving
> > force.
>
> > Some 200years ago, Stephenson's first viable railroad
> > locomotive, powered by a steam engine, was named
> > 'The Rocket.'
>
> > So I am wondering if the term 'rocket' meant something
> > else at that time? Or were rockets, in the presently
> > accepted meaning of the term, known at the time?
>
> > Rune
>
> It's a kind of green used in salads.=96 Skjul sitert tekst =96
>
> =96 Vis sitert tekst =96

Ah! So Stephenson used the name as PR directed
towards grocery farmers, who would want to get
their produce into town while it was still fresh!

Rune

On 10/12/2011 19:35, HardySpicer wrote:
>..
>> So I am wondering if the term 'rocket' meant something
>> else at that time? Or were rockets, in the presently
>> accepted meaning of the term, known at the time?
>>
>> Rune
>
> It's a kind of green used in salads.

And quite strong/peppery in taste - sort of warming!

Richard Dobson

On 12/10/2011 3:21 PM, Richard Dobson wrote:
> On 10/12/2011 18:20, Jerry Avins wrote:
> ..
>>> The OED has it from 1611 in English, to signify the firework. The word
>>> existed long before with other meanings (including the salad plant).
>>> Fireworks were of course brought back, along with the gunpowder they
>>> involved, from China and widely used, especially for grand celebrations
>>> (hence, G.F. Handel, "Music for the Royal Fireworks"). The alchemists
>>> probably got involved too, one way and another. According to the OED,
>>> the name "rocket" included squibs and other pyrotechnics, as well as
>>> rockets fired into the sky. The composer Stamitz (mid-18th Century)
>>> gained considerable fame composing symphonies for the orchestra at
>>> Mannheim including dramatic upward-rushing scale figures, popularly
>>> known thereafter as the "Mannheim Skyrocket". So we may surmise that the
>>> name was chosen by Stevenson as evoking an image of speed along with
>>> magic, shock and awe, plus no doubt the literal internal combustion
>>> aspect too.
>>
>> Tut tut, Richard! Stephenson's Rocket had a boiler, as I'm sureyou know.
>>
>> Jerry
>
> Well yes, but it was burning ~something~, in a firebox, sort of
> internally...did you think I meant petrol? :-)

I knew you didn't mean that, but it is what you said. Otto and Diesel 
engines are called "internal combustion" engines because the combustion 
takes place in the working cylinder. I imagine jet engines are in the 
same category, but I've not heard them so called. "External combustion" 
describes most steam engines including turbines, and Stirling engines.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On 12/10/2011 12:21 PM, Rune Allnor wrote:
> On 10 Des, 20:35, HardySpicer<gyansor...@gmail.com>  wrote:
>> On Dec 11, 4:22 am, Rune Allnor<all...@tele.ntnu.no>  wrote:
>>
>>
>>
>>
>>
>>> Hi all.
>>
>>> These days the word 'rocket' is used to denote a flying
>>> missile, propelled by the rapid intrenal burning of some
>>> fuel, where the expelled exhaust gases provide the driving
>>> force.
>>
>>> Some 200years ago, Stephenson's first viable railroad
>>> locomotive, powered by a steam engine, was named
>>> 'The Rocket.'
>>
>>> So I am wondering if the term 'rocket' meant something
>>> else at that time? Or were rockets, in the presently
>>> accepted meaning of the term, known at the time?
>>
>>> Rune
>>

Lotta posts.  Did anyone mention "rocket" as a verb?

"Joe rocketed to the bar when he learned his girlfriend was there alone"

rocketed past tense of:
"rocket" meaning to move swiftly and powerfully, as a rocket.

Fred

Jerry Avins <jya@ieee.org> wrote:

(snip)
>> Well yes, but it was burning ~something~, in a firebox, sort of
>> internally...did you think I meant petrol? :-)

> I knew you didn't mean that, but it is what you said. Otto and Diesel 
> engines are called "internal combustion" engines because the combustion 
> takes place in the working cylinder. I imagine jet engines are in the 
> same category, but I've not heard them so called. 

I haven't thought about this for a while.  I had thought that the
distinction was that for internal combustion the oxygen supply is
fixed before combustion starts.  Maybe fuel, also.  As combustion
procedes, it does so at ever decreasing oxygen concentration.

> "External combustion"  describes most steam engines including 
> turbines, and Stirling engines.

And also a continuous supply of fuel and oxidizer.  That would seem
to me to make them more similar to jet engines. (or the other 
way around.)

-- glen

On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
> Jerry Avins<jya@ieee.org>  wrote:
>
> (snip)
>>> Well yes, but it was burning ~something~, in a firebox, sort of
>>> internally...did you think I meant petrol? :-)
>
>> I knew you didn't mean that, but it is what you said. Otto and Diesel
>> engines are called "internal combustion" engines because the combustion
>> takes place in the working cylinder. I imagine jet engines are in the
>> same category, but I've not heard them so called.
>
> I haven't thought about this for a while.  I had thought that the
> distinction was that for internal combustion the oxygen supply is
> fixed before combustion starts.  Maybe fuel, also.  As combustion
> procedes, it does so at ever decreasing oxygen concentration.
>
>> "External combustion"  describes most steam engines including
>> turbines, and Stirling engines.
>
> And also a continuous supply of fuel and oxidizer.  That would seem
> to me to make them more similar to jet engines. (or the other
> way around.)

Wouldn't "continuous combustion" be a more apt description then?

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On 11 Des, 04:40, Jerry Avins <j...@ieee.org> wrote:
> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>
>
>
>
>
> > Jerry Avins<j...@ieee.org> =A0wrote:
>
> > (snip)
> >>> Well yes, but it was burning ~something~, in a firebox, sort of
> >>> internally...did you think I meant petrol? :-)
>
> >> I knew you didn't mean that, but it is what you said. Otto and Diesel
> >> engines are called "internal combustion" engines because the combustio=
n
> >> takes place in the working cylinder. I imagine jet engines are in the
> >> same category, but I've not heard them so called.
>
> > I haven't thought about this for a while. =A0I had thought that the
> > distinction was that for internal combustion the oxygen supply is
> > fixed before combustion starts. =A0Maybe fuel, also. =A0As combustion
> > procedes, it does so at ever decreasing oxygen concentration.
>
> >> "External combustion" =A0describes most steam engines including
> >> turbines, and Stirling engines.
>
> > And also a continuous supply of fuel and oxidizer. =A0That would seem
> > to me to make them more similar to jet engines. (or the other
> > way around.)
>
> Wouldn't "continuous combustion" be a more apt description then?

For what? Both the biler in a steam engine and the
combustion chamber of a jet engine would classify
as 'continuous'. But the steam engine uses external
combustion (the furnace (?) is external to the
pressure chamber - pistons) while the jet engine
combustion is internal - it generates the pressure
that drives the rear fan.

Rune

On 11/12/2011 04:40, Rune Allnor wrote:
...
>> Wouldn't "continuous combustion" be a more apt description then?
>
> For what? Both the biler in a steam engine and the
> combustion chamber of a jet engine would classify
> as 'continuous'. But the steam engine uses external
> combustion (the furnace (?) is external to the
> pressure chamber - pistons) while the jet engine
> combustion is internal - it generates the pressure
> that drives the rear fan.
>
> Rune

The thing is, "internal combustion" has a nice ring to it (it is also a 
good description of a curry (or a description of a good curry), btw). 
That makes it viable as a metaphor.

At least I didn't call the thing a "quantum leap". But one cannot always 
predict what will lead to a cool discussion!

Richard Dobson

On 12/10/2011 11:40 PM, Rune Allnor wrote:
> On 11 Des, 04:40, Jerry Avins<j...@ieee.org>  wrote:
>> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>>
>>
>>
>>
>>
>>> Jerry Avins<j...@ieee.org>    wrote:
>>
>>> (snip)
>>>>> Well yes, but it was burning ~something~, in a firebox, sort of
>>>>> internally...did you think I meant petrol? :-)
>>
>>>> I knew you didn't mean that, but it is what you said. Otto and Diesel
>>>> engines are called "internal combustion" engines because the combustion
>>>> takes place in the working cylinder. I imagine jet engines are in the
>>>> same category, but I've not heard them so called.
>>
>>> I haven't thought about this for a while.  I had thought that the
>>> distinction was that for internal combustion the oxygen supply is
>>> fixed before combustion starts.  Maybe fuel, also.  As combustion
>>> procedes, it does so at ever decreasing oxygen concentration.
>>
>>>> "External combustion"  describes most steam engines including
>>>> turbines, and Stirling engines.
>>
>>> And also a continuous supply of fuel and oxidizer.  That would seem
>>> to me to make them more similar to jet engines. (or the other
>>> way around.)
>>
>> Wouldn't "continuous combustion" be a more apt description then?
>
> For what? Both the biler in a steam engine and the
> combustion chamber of a jet engine would classify
> as 'continuous'. But the steam engine uses external
> combustion (the furnace (?) is external to the
> pressure chamber - pistons) while the jet engine
> combustion is internal - it generates the pressure
> that drives the rear fan.

Internal or external combustion is one division, while continuous or 
intermittent combustion is another. As far as I know, all external 
combustion engines are continuous, while internal combustion can be 
either. Typical jet engines -- Brayton cycle and ramjet -- are 
internal-continuous, but pulse jets are internal-intermittent, like 
Diesel and Otto engines. If we try, we could probably invent more 
classifications, but I'm content to stop here.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On Sun, 11 Dec 2011 12:07:23 -0500, Jerry Avins <jya@ieee.org> wrote:

>On 12/10/2011 11:40 PM, Rune Allnor wrote:
>> On 11 Des, 04:40, Jerry Avins<j...@ieee.org>  wrote:
>>> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>>>
>>>
>>>
>>>
>>>
>>>> Jerry Avins<j...@ieee.org>    wrote:
>>>
>>>> (snip)
>>>>>> Well yes, but it was burning ~something~, in a firebox, sort of
>>>>>> internally...did you think I meant petrol? :-)
>>>
>>>>> I knew you didn't mean that, but it is what you said. Otto and Diesel
>>>>> engines are called "internal combustion" engines because the combustion
>>>>> takes place in the working cylinder. I imagine jet engines are in the
>>>>> same category, but I've not heard them so called.
>>>
>>>> I haven't thought about this for a while.  I had thought that the
>>>> distinction was that for internal combustion the oxygen supply is
>>>> fixed before combustion starts.  Maybe fuel, also.  As combustion
>>>> procedes, it does so at ever decreasing oxygen concentration.
>>>
>>>>> "External combustion"  describes most steam engines including
>>>>> turbines, and Stirling engines.
>>>
>>>> And also a continuous supply of fuel and oxidizer.  That would seem
>>>> to me to make them more similar to jet engines. (or the other
>>>> way around.)
>>>
>>> Wouldn't "continuous combustion" be a more apt description then?
>>
>> For what? Both the biler in a steam engine and the
>> combustion chamber of a jet engine would classify
>> as 'continuous'. But the steam engine uses external
>> combustion (the furnace (?) is external to the
>> pressure chamber - pistons) while the jet engine
>> combustion is internal - it generates the pressure
>> that drives the rear fan.
>
>Internal or external combustion is one division, while continuous or 
>intermittent combustion is another. As far as I know, all external 
>combustion engines are continuous, while internal combustion can be 
>either. Typical jet engines -- Brayton cycle and ramjet -- are 
>internal-continuous, but pulse jets are internal-intermittent, like 
>Diesel and Otto engines. If we try, we could probably invent more 
>classifications, but I'm content to stop here.
>
>Jerry
>-- 
>Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Yeah, even among "internal intermittent" there's reciprocal and
rotary.  And within both of those there are a number of subsets,
especially for reciprocal.

There's no reason one couldn't use an intermittent external combustion
as long as the energy flow still worked right.   I'm imagining
intermittent applications of something really hot like thermite to a
heatsink that then keeps the water boiling for a steam engine.

I don't know that anything like that has actually been built, but
clearly it could be.


Eric Jacobsen
Anchor Hill Communications
www.anchorhill.com

On 11 Des, 18:48, eric.jacob...@ieee.org (Eric Jacobsen) wrote:

> There's no reason one couldn't use an intermittent external combustion
> as long as the energy flow still worked right. =A0 I'm imagining
> intermittent applications of something really hot like thermite to a
> heatsink that then keeps the water boiling for a steam engine.
>
> I don't know that anything like that has actually been built, but
> clearly it could be.

Isn't that how nuclear powerplants work?
Radiacive fuel -> heat -> steam -> electrics?

Rune

On Sun, 11 Dec 2011 09:53:11 -0800 (PST), Rune Allnor
<allnor@tele.ntnu.no> wrote:

>On 11 Des, 18:48, eric.jacob...@ieee.org (Eric Jacobsen) wrote:
>
>> There's no reason one couldn't use an intermittent external combustion
>> as long as the energy flow still worked right. =A0 I'm imagining
>> intermittent applications of something really hot like thermite to a
>> heatsink that then keeps the water boiling for a steam engine.
>>
>> I don't know that anything like that has actually been built, but
>> clearly it could be.
>
>Isn't that how nuclear powerplants work?
>Radiacive fuel -> heat -> steam -> electrics?
>
>Rune

Even in a nuclear system the heat from the reaction is applied
continuously, not intermittently, at least not intermittently enough
to think of it as such when comparing the systems previously
discussed.

And one usually hopes that with a nuclear system "combustion" isn't
involved.   ;)


Eric Jacobsen
Anchor Hill Communications
www.anchorhill.com

Eric Jacobsen <eric.jacobsen@ieee.org> wrote:

(snip)
> Even in a nuclear system the heat from the reaction is applied
> continuously, not intermittently, at least not intermittently enough
> to think of it as such when comparing the systems previously
> discussed.

There have been suggestions for fusion power that really
are intermittent, generating heat from a reaction every so many
minutes or even hours.  

> And one usually hopes that with a nuclear system "combustion" isn't
> involved.   ;)

-- glen

On Dec 11, 12:48=A0pm, eric.jacob...@ieee.org (Eric Jacobsen) wrote:
> On Sun, 11 Dec 2011 12:07:23 -0500, Jerry Avins <j...@ieee.org> wrote:
> >On 12/10/2011 11:40 PM, Rune Allnor wrote:
> >> On 11 Des, 04:40, Jerry Avins<j...@ieee.org> =A0wrote:
> >>> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>
> >>>> Jerry Avins<j...@ieee.org> =A0 =A0wrote:
>
> >>>> (snip)
> >>>>>> Well yes, but it was burning ~something~, in a firebox, sort of
> >>>>>> internally...did you think I meant petrol? :-)
>
> >>>>> I knew you didn't mean that, but it is what you said. Otto and Dies=
el
> >>>>> engines are called "internal combustion" engines because the combus=
tion
> >>>>> takes place in the working cylinder. I imagine jet engines are in t=
he
> >>>>> same category, but I've not heard them so called.
>
> >>>> I haven't thought about this for a while. =A0I had thought that the
> >>>> distinction was that for internal combustion the oxygen supply is
> >>>> fixed before combustion starts. =A0Maybe fuel, also. =A0As combustio=
n
> >>>> procedes, it does so at ever decreasing oxygen concentration.
>
> >>>>> "External combustion" =A0describes most steam engines including
> >>>>> turbines, and Stirling engines.
>
> >>>> And also a continuous supply of fuel and oxidizer. =A0That would see=
m
> >>>> to me to make them more similar to jet engines. (or the other
> >>>> way around.)
>
> >>> Wouldn't "continuous combustion" be a more apt description then?
>
> >> For what? Both the biler in a steam engine and the
> >> combustion chamber of a jet engine would classify
> >> as 'continuous'. But the steam engine uses external
> >> combustion (the furnace (?) is external to the
> >> pressure chamber - pistons) while the jet engine
> >> combustion is internal - it generates the pressure
> >> that drives the rear fan.
>
> >Internal or external combustion is one division, while continuous or
> >intermittent combustion is another. As far as I know, all external
> >combustion engines are continuous, while internal combustion can be
> >either. Typical jet engines -- Brayton cycle and ramjet -- are
> >internal-continuous, but pulse jets are internal-intermittent, like
> >Diesel and Otto engines. If we try, we could probably invent more
> >classifications, but I'm content to stop here.
>
> >Jerry
> >--
> >Engineering is the art of making what you want from things you can get.
>
> =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF
> Yeah, even among "internal intermittent" there's reciprocal and
> rotary. =A0And within both of those there are a number of subsets,
> especially for reciprocal.
>
> There's no reason one couldn't use an intermittent external combustion
> as long as the energy flow still worked right. =A0 I'm imagining
> intermittent applications of something really hot like thermite to a
> heatsink that then keeps the water boiling for a steam engine.
>
> I don't know that anything like that has actually been built, but
> clearly it could be.
>
> Eric Jacobsen
> Anchor Hill Communicationswww.anchorhill.com- Hide quoted text -
>
> - Show quoted text -

On Dec 11, 12:48=A0pm, eric.jacob...@ieee.org (Eric Jacobsen) wrote:
> On Sun, 11 Dec 2011 12:07:23 -0500, Jerry Avins <j...@ieee.org> wrote:
> >On 12/10/2011 11:40 PM, Rune Allnor wrote:
> >> On 11 Des, 04:40, Jerry Avins<j...@ieee.org> =A0wrote:
> >>> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>
> >>>> Jerry Avins<j...@ieee.org> =A0 =A0wrote:
>
> >>>> (snip)
> >>>>>> Well yes, but it was burning ~something~, in a firebox, sort of
> >>>>>> internally...did you think I meant petrol? :-)
>
> >>>>> I knew you didn't mean that, but it is what you said. Otto and Dies=
el
> >>>>> engines are called "internal combustion" engines because the combus=
tion
> >>>>> takes place in the working cylinder. I imagine jet engines are in t=
he
> >>>>> same category, but I've not heard them so called.
>
> >>>> I haven't thought about this for a while. =A0I had thought that the
> >>>> distinction was that for internal combustion the oxygen supply is
> >>>> fixed before combustion starts. =A0Maybe fuel, also. =A0As combustio=
n
> >>>> procedes, it does so at ever decreasing oxygen concentration.
>
> >>>>> "External combustion" =A0describes most steam engines including
> >>>>> turbines, and Stirling engines.
>
> >>>> And also a continuous supply of fuel and oxidizer. =A0That would see=
m
> >>>> to me to make them more similar to jet engines. (or the other
> >>>> way around.)
>
> >>> Wouldn't "continuous combustion" be a more apt description then?
>
> >> For what? Both the biler in a steam engine and the
> >> combustion chamber of a jet engine would classify
> >> as 'continuous'. But the steam engine uses external
> >> combustion (the furnace (?) is external to the
> >> pressure chamber - pistons) while the jet engine
> >> combustion is internal - it generates the pressure
> >> that drives the rear fan.
>
> >Internal or external combustion is one division, while continuous or
> >intermittent combustion is another. As far as I know, all external
> >combustion engines are continuous, while internal combustion can be
> >either. Typical jet engines -- Brayton cycle and ramjet -- are
> >internal-continuous, but pulse jets are internal-intermittent, like
> >Diesel and Otto engines. If we try, we could probably invent more
> >classifications, but I'm content to stop here.
>
> >Jerry
> >--
> >Engineering is the art of making what you want from things you can get.
>
> =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF
> Yeah, even among "internal intermittent" there's reciprocal and
> rotary. =A0And within both of those there are a number of subsets,
> especially for reciprocal.
>
> There's no reason one couldn't use an intermittent external combustion
> as long as the energy flow still worked right. =A0 I'm imagining
> intermittent applications of something really hot like thermite to a
> heatsink that then keeps the water boiling for a steam engine.
>
> I don't know that anything like that has actually been built, but
> clearly it could be.
>
> Eric Jacobsen
> Anchor Hill Communicationswww.anchorhill.com- Hide quoted text -
>
> - Show quoted text -

Well it is not combustion, but it is surely intermittant. Back in the
1960s two nukes were set off underground in a Missisippi salt dome
mostly for seismic studies but also to hopefully store heat to be used
over a period of time. Needless to say the thermal storage didn't work
very well.

Clay

On Dec 12, 12:45=A0am, glen herrmannsfeldt <g...@ugcs.caltech.edu>
wrote:
> Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>
> (snip)
>
> > Even in a nuclear system the heat from the reaction is applied
> > continuously, not intermittently, at least not intermittently enough
> > to think of it as such when comparing the systems previously
> > discussed.
>
> There have been suggestions for fusion power that really
> are intermittent, generating heat from a reaction every so many
> minutes or even hours.
>
> > And one usually hopes that with a nuclear system "combustion" isn't
> > involved. =A0 ;)

Sadly the plutonium processing facility, Rocky Flats (now razed)
caught fire (plutonium burns very easily!) and radioactive smoked was
vented to the atmosphere!

Clay


>
> -- glen

On Dec 11, 9:07=A0am, Jerry Avins <j...@ieee.org> wrote:
> On 12/10/2011 11:40 PM, Rune Allnor wrote:
>
>
>
> > On 11 Des, 04:40, Jerry Avins<j...@ieee.org> =A0wrote:
> >> On 12/10/2011 4:56 PM, glen herrmannsfeldt wrote:
>
> >>> Jerry Avins<j...@ieee.org> =A0 =A0wrote:
>
> >>> (snip)
> >>>>> Well yes, but it was burning ~something~, in a firebox, sort of
> >>>>> internally...did you think I meant petrol? :-)
>
> >>>> I knew you didn't mean that, but it is what you said. Otto and Diese=
l
> >>>> engines are called "internal combustion" engines because the combust=
ion
> >>>> takes place in the working cylinder. I imagine jet engines are in th=
e
> >>>> same category, but I've not heard them so called.
>
> >>> I haven't thought about this for a while. =A0I had thought that the
> >>> distinction was that for internal combustion the oxygen supply is
> >>> fixed before combustion starts. =A0Maybe fuel, also. =A0As combustion
> >>> procedes, it does so at ever decreasing oxygen concentration.
>
> >>>> "External combustion" =A0describes most steam engines including
> >>>> turbines, and Stirling engines.
>
> >>> And also a continuous supply of fuel and oxidizer. =A0That would seem
> >>> to me to make them more similar to jet engines. (or the other
> >>> way around.)
>
> >> Wouldn't "continuous combustion" be a more apt description then?
>
> > For what? Both the biler in a steam engine and the
> > combustion chamber of a jet engine would classify
> > as 'continuous'. But the steam engine uses external
> > combustion (the furnace (?) is external to the
> > pressure chamber - pistons) while the jet engine
> > combustion is internal - it generates the pressure
> > that drives the rear fan.
>
> Internal or external combustion is one division, while continuous or
> intermittent combustion is another. As far as I know, all external
> combustion engines are continuous, while internal combustion can be
> either. Typical jet engines -- Brayton cycle and ramjet -- are
> internal-continuous, but pulse jets are internal-intermittent, like
> Diesel and Otto engines. If we try, we could probably invent more
> classifications, but I'm content to stop here.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> =AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=
=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF=AF

An important distinction is where the oxidizer comes from: jets
typically require
atmospheric oxygen to burn a stored fuel; rockets carry their own
oxidizers, so
may operate in a vacuum as well as in the atmosphere.

>Eric Jacobsen <eric.jacobsen@ieee.org> wrote:
>
>(snip)
>> Even in a nuclear system the heat from the reaction is applied
>> continuously, not intermittently, at least not intermittently enough
>> to think of it as such when comparing the systems previously
>> discussed.
>
>There have been suggestions for fusion power that really
>are intermittent, generating heat from a reaction every so many
>minutes or even hours.  

Has there been a proposal for fusion power which is *not* intermittent? The
containment rings, laser bombarders, and other strategies all seem to take
a measure of fuel, make it pop, and then start again with another measure
of fuel. The small scale continuous fusers, used for medical and research
purposes, don't ever seem to have been seriously proposed as a power
source.

>> And one usually hopes that with a nuclear system "combustion" isn't
>> involved.   ;)

Steve

On 12/13/2011 11:19 AM, cassiope wrote:

   ...

> An important distinction is where the oxidizer comes from: jets
> typically require
> atmospheric oxygen to burn a stored fuel; rockets carry their own
> oxidizers, so
> may operate in a vacuum as well as in the atmosphere.

Back when I was a kid and Buck Rogers* was popular, some people argued 
that rockets couldn't operate outside the atmosphere because there would 
be nothing for the exhaust plume to push against. Not just some of my 
contemporaries, but adults also. It's very hard to explain anything to 
people like that. They're still around today, but the subjects are 
different.

Jerry
______________________________
* http://en.wikipedia.org/wiki/Buck_Rogers
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

steveu <steveu@n_o_s_p_a_m.coppice.org> wrote:
>>Eric Jacobsen <eric.jacobsen@ieee.org> wrote:
>>(snip)
>>> Even in a nuclear system the heat from the reaction is applied
>>> continuously, not intermittently, at least not intermittently enough
>>> to think of it as such when comparing the systems previously
>>> discussed.

(snip, then I wrote)
>> There have been suggestions for fusion power that really
>> are intermittent, generating heat from a reaction every so many
>> minutes or even hours.  

> Has there been a proposal for fusion power which is *not* intermittent? 

As Clinton would say, it depends on what intermittent means.

I would say that Tokamacs were not intermittent.  

The usual fission reactor design is shut down every few years to
replace the fuel rods, so is that intermittent?

The distinction I was making originally was between engines that
fill with reactants, close off the combustion chamber, and then
start the reaction.  The available reactants then change during
combustion as exhaust products build up and others are consumed.

In others, fuel and oxidizer are continuously supplied, such that
the reaction soon reaches, and mostly remains in, an equilibrium
of input reactants and exhaust products.

The distinction then, is the fraction of the time the system is
in equilibrium (steady state) or not (transient).  That distinction
should be on-topic for this group.  

My 30 year old stereo amplifier has a relay to delay connection
to the speakers until a second or two after power on to be sure that
any transients have died down.  (And I have had to replace two 
capacitors in that circuit over the years.)

Most likely some DSP systems also need to let the transients decay.

> The containment rings, laser bombarders, and other strategies all 
> seem to take a measure of fuel, make it pop, and then start again 
> with another measure of fuel. The small scale continuous fusers, 
> used for medical and research purposes, don't ever seem to have 
> been seriously proposed as a power source.

I don't remember by now if Tokamacs can have fuel added while running.
The plasma physics is not easy, and it might be that they can't, or
that it is easier just not to run them that way.  There are other
magnetic confinement systems that may or may not run more
continuously.

They do, however, run the reaction fairly slowly compared to bombs
or to pellet type reactors.

-- glen

Jerry Avins <jya@ieee.org> wrote:

(snip)
> Back when I was a kid and Buck Rogers* was popular, some people argued 
> that rockets couldn't operate outside the atmosphere because there would 
> be nothing for the exhaust plume to push against. Not just some of my 
> contemporaries, but adults also. It's very hard to explain anything to 
> people like that. They're still around today, but the subjects are 
> different.

There is a discussion ongoing (for weeks) in another newsgroup on
the recoil from a rail gun.  The suggestion is that if one can
build a recoilless gun, one can power the rocket by shooting 
bullets into a block, and using the bullet momentum to power
the rocket.  As above, it isn't easy to show where the momentum
transfer is done to the rocket.

-- glen

On 12/13/2011 2:27 PM, glen herrmannsfeldt wrote:
> Jerry Avins<jya@ieee.org>  wrote:
>
> (snip)
>> Back when I was a kid and Buck Rogers* was popular, some people argued
>> that rockets couldn't operate outside the atmosphere because there would
>> be nothing for the exhaust plume to push against. Not just some of my
>> contemporaries, but adults also. It's very hard to explain anything to
>> people like that. They're still around today, but the subjects are
>> different.
>
> There is a discussion ongoing (for weeks) in another newsgroup on
> the recoil from a rail gun.  The suggestion is that if one can
> build a recoilless gun, one can power the rocket by shooting
> bullets into a block, and using the bullet momentum to power
> the rocket.  As above, it isn't easy to show where the momentum
> transfer is done to the rocket.

We user to wonder how far we could power a rowboat by peeing over the 
transom. How does the notion arise that a rail gun has no recoil?

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On 13 Des, 21:23, Jerry Avins <j...@ieee.org> wrote:
> On 12/13/2011 2:27 PM, glen herrmannsfeldt wrote:
>
>
>
>
>
> > Jerry Avins<j...@ieee.org> =A0wrote:
>
> > (snip)
> >> Back when I was a kid and Buck Rogers* was popular, some people argued
> >> that rockets couldn't operate outside the atmosphere because there wou=
ld
> >> be nothing for the exhaust plume to push against. Not just some of my
> >> contemporaries, but adults also. It's very hard to explain anything to
> >> people like that. They're still around today, but the subjects are
> >> different.
>
> > There is a discussion ongoing (for weeks) in another newsgroup on
> > the recoil from a rail gun. =A0The suggestion is that if one can
> > build a recoilless gun, one can power the rocket by shooting
> > bullets into a block, and using the bullet momentum to power
> > the rocket. =A0As above, it isn't easy to show where the momentum
> > transfer is done to the rocket.
>
> We user to wonder how far we could power a rowboat by peeing over the
> transom.

Once upon a time I used a drop of oil to propell
a small carboard boat: Cut a shape like this out
of carboard (view with fixed-width font):


     ____________
    /            |
   <         C=3D=3D=3D
    \____________|

Then drip some oil in the 'C' at the rear. The oil's
area will expand on the surface of the water, escaping
out the slit, pushing the boat in the forward direction.

> How does the notion arise that a rail gun has no recoil?

Well, the rail gun works by exposing a magnet to a
powerful electric field, causing the magnet to move.
As the magnet moves through the coil, it produces an
equally strong current as the current that drives the
gun in the first place.

Whether that counts as 'recoil' is a matter of
definition; it might not cause much mechanical momentum,
but the current certainly _RE_verberates thtrough
the _COIL_...

Rune

Jerry Avins <jya@ieee.org> wrote:

(snip, I wrote)
>> There is a discussion ongoing (for weeks) in another newsgroup on
>> the recoil from a rail gun.  The suggestion is that if one can
>> build a recoilless gun, one can power the rocket by shooting
>> bullets into a block, and using the bullet momentum to power
>> the rocket.  As above, it isn't easy to show where the momentum
>> transfer is done to the rocket.

> We user to wonder how far we could power a rowboat by peeing over the 
> transom. How does the notion arise that a rail gun has no recoil?

Good question.  From I cross B, the force on a wire (infinitely
thin at that) has no component along the wire.  There is, then,
no reaction force on the rails.  You can make the far end as
far away as you want, decreasing the reaction on the far end.

The "low recoil on the rails" part has been tested using 
Gallium-Indium contacts to pass current but no force into
the rails.  (Leaving the recoil to the rest of the circuit.)

If you google for IFE and railgun it should come up.

(I believe IFE is internal force engine.)

-- glen

On Tue, 13 Dec 2011 15:23:17 -0500, Jerry Avins <jya@ieee.org> wrote:

>On 12/13/2011 2:27 PM, glen herrmannsfeldt wrote:
>> Jerry Avins<jya@ieee.org>  wrote:
>>
>> (snip)
>>> Back when I was a kid and Buck Rogers* was popular, some people argued
>>> that rockets couldn't operate outside the atmosphere because there would
>>> be nothing for the exhaust plume to push against. Not just some of my
>>> contemporaries, but adults also. It's very hard to explain anything to
>>> people like that. They're still around today, but the subjects are
>>> different.
>>
>> There is a discussion ongoing (for weeks) in another newsgroup on
>> the recoil from a rail gun.  The suggestion is that if one can
>> build a recoilless gun, one can power the rocket by shooting
>> bullets into a block, and using the bullet momentum to power
>> the rocket.  As above, it isn't easy to show where the momentum
>> transfer is done to the rocket.
>
>We user to wonder how far we could power a rowboat by peeing over the 
>transom.

Was there experimentation done to investigate that?   ;)

> How does the notion arise that a rail gun has no recoil?

I think the same sort of thinking that led to the "rockets don't work
in space" discussions.  Not everybody gets physics, which is okay, but
once it's been explained one would think that would end it, and is
does for many people.   The ones that insist on clinging to
misconceptions provide the majority of the entertainment, or
frustration, depending.  ;)


Eric Jacobsen
Anchor Hill Communications
www.anchorhill.com

On 12/13/2011 3:35 PM, Rune Allnor wrote:
> On 13 Des, 21:23, Jerry Avins<j...@ieee.org>  wrote:
>> On 12/13/2011 2:27 PM, glen herrmannsfeldt wrote:
>>
>>
>>
>>
>>
>>> Jerry Avins<j...@ieee.org>    wrote:
>>
>>> (snip)
>>>> Back when I was a kid and Buck Rogers* was popular, some people argued
>>>> that rockets couldn't operate outside the atmosphere because there would
>>>> be nothing for the exhaust plume to push against. Not just some of my
>>>> contemporaries, but adults also. It's very hard to explain anything to
>>>> people like that. They're still around today, but the subjects are
>>>> different.
>>
>>> There is a discussion ongoing (for weeks) in another newsgroup on
>>> the recoil from a rail gun.  The suggestion is that if one can
>>> build a recoilless gun, one can power the rocket by shooting
>>> bullets into a block, and using the bullet momentum to power
>>> the rocket.  As above, it isn't easy to show where the momentum
>>> transfer is done to the rocket.
>>
>> We user to wonder how far we could power a rowboat by peeing over the
>> transom.
>
> Once upon a time I used a drop of oil to propell
> a small carboard boat: Cut a shape like this out
> of carboard (view with fixed-width font):
>
>
>       ____________
>      /            |
>     <          C===
>      \____________|
>
> Then drip some oil in the 'C' at the rear. The oil's
> area will expand on the surface of the water, escaping
> out the slit, pushing the boat in the forward direction.

I remember doing the same. A piece of soap molded to the rear also moves 
the "boat" forward with what is in the end the same mechanism. By 
reducing the surface tension at the rear, the tension at the front pulls 
it forward. Camphor works the other way. It raises surface tension, so a 
piece at the front of the boat propels it forward.

>> How does the notion arise that a rail gun has no recoil?
>
> Well, the rail gun works by exposing a magnet to a
> powerful electric field, causing the magnet to move.
> As the magnet moves through the coil, it produces an
> equally strong current as the current that drives the
> gun in the first place.
>
> Whether that counts as 'recoil' is a matter of
> definition; it might not cause much mechanical momentum,
> but the current certainly _RE_verberates thtrough
> the _COIL_...

The mechanism doesn't matter. The gun must acquire as much momentum 
backward as is imparted to the projectile in the forward direction. F=Ma 
in any case.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

On 12/13/2011 3:58 PM, glen herrmannsfeldt wrote:
> Jerry Avins<jya@ieee.org>  wrote:
>
> (snip, I wrote)
>>> There is a discussion ongoing (for weeks) in another newsgroup on
>>> the recoil from a rail gun.  The suggestion is that if one can
>>> build a recoilless gun, one can power the rocket by shooting
>>> bullets into a block, and using the bullet momentum to power
>>> the rocket.  As above, it isn't easy to show where the momentum
>>> transfer is done to the rocket.
>
>> We user to wonder how far we could power a rowboat by peeing over the
>> transom. How does the notion arise that a rail gun has no recoil?
>
> Good question.  From I cross B, the force on a wire (infinitely
> thin at that) has no component along the wire.  There is, then,
> no reaction force on the rails.  You can make the far end as
> far away as you want, decreasing the reaction on the far end.
>
> The "low recoil on the rails" part has been tested using
> Gallium-Indium contacts to pass current but no force into
> the rails.  (Leaving the recoil to the rest of the circuit.)
>
> If you google for IFE and railgun it should come up.
>
> (I believe IFE is internal force engine.)

Oh, Wonderful! Let's bend the rail into a circle, and have the 
"projectile" move around it and turn a shaft. Then we can generate 
torque without counter torque. That would be a great way to power a 
helicopter or torpedo.

Wikipedia likens the action to a homopolar motor. If a homopolar motor 
drives a ships propeller shaft, is there no torque reaction at the motor 
mounts?

Jerry
-- 
Engineering is the art of making what you want from things you can get.
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