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Re: [pop-pop-steamboats] Re: Peter R Payne and proper boats.

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  • David Halfpenny
    ... From: Richard Mundy Sent: Tuesday, January 20, 2009 10:02 PM To: Subject:
    Message 1 of 29 , Jan 21, 2009
      --------------------------------------------------
      From: "Richard Mundy" <coracles18@...>
      Sent: Tuesday, January 20, 2009 10:02 PM
      To: <pop-pop-steamboats@yahoogroups.com>
      Subject: [pop-pop-steamboats] Re: Peter R Payne and proper boats.

      > Hi David,
      > I think the condensing is done in the tube, which creates another
      > problem. Condensing steam in a tiny tube is a lot quicker than doing
      > it in a big tube.
      > An interesting aspect of Paynes original patent is using the momentum
      > of the returning water to compress the remaining steam in the boiler.
      > This should raise the boiling point so the steam has more kick to it.
      > If this effect is significant I have no idea.
      > More important I suspect is to have a forward facing intake and
      > valves.
      > Also, what about an output nozzle? you can significantly increase the
      > velocity of water coming out of a hosepipe by sticking your finger
      > over the end.
      > This would also increase the pressure in the boiler and give the
      > whole thing more go?
      >

      This is basically a bit of fun in the bathtub. But if Payne missed
      something big, as well he might, then we aren't going to find it in this
      kind of conversation, entertaining as it is.

      We are talking about a resonant system involving an air spring of unknown
      size, ever-reversing heat flow, the properties of steam and water under
      rapidly varying pressure, and the movement of a heavy craft at low speed
      under tiny fluctuating loads. There is virtually no experimental data, and
      few if any of our members have either the maths, the mechanics or the
      thermodynamics to discuss any part of it at a theoretical level. Despite
      the simplicity of the device, it is vastly more complicated than, say, an
      ordinary three cylinder compound marine steam engine. It has been usefully
      demonstrated by Payne that when scaled up in a simple manner the power
      required became enormous yet the result remained pathetic.

      What would be needed to improve on that would be a set of experiments in
      which every part of the apparatus had rapid-acting pressure and temperature
      sensors, backed up an ever more sophisticated non-linear computer "model"
      based on real thermodynamics until the whole process was understood.

      The exciting thing is that this is actually all within the scope of a smart
      pensioner with modest means.

      Meanwhile, the complexity is such that the best answer to questions about
      valves and nozzles is still "Try it!" (Please.)

      David 1/2d
    • Richard Mundy
      Hi Matt, good to hear from you, I remember something similar using a wheelchair. Quite exiting for the occupier of the wheelchair,but it was all over quite
      Message 2 of 29 , Jan 21, 2009
        Hi Matt, good to hear from you,

        I remember something similar using a wheelchair. Quite exiting for
        the occupier of the wheelchair,but it was all over quite quickly.
        Problem with a boat is it won't go any spead unless you can get it on
        the plane, which takes a lot of energy! The boat needs to be lifted
        out and placed on top of the water.
        Even I am not optimistic enough to expect to get a pop pop to plane.

        Dick

        --- In pop-pop-steamboats@yahoogroups.com, "Sparks, Matthew -
        McClatchy Corporate" <msparks@...> wrote:
        >
        > If you really want to see what you're up against, check out the
        > mythbusters episode where they took a fiberglass speedboat hull and
        > mounted two of the large compressed air cylineders.
        >
        > http://televizzle.org/2006/12/06/air-cylinder-rocket/
        >
        > Matt Sparks -
        >
        > -----Original Message-----
        > From: pop-pop-steamboats@yahoogroups.com
        > [mailto:pop-pop-steamboats@yahoogroups.com] On Behalf Of Richard
        Mundy
        > Sent: Tuesday, January 20, 2009 2:03 PM
        > To: pop-pop-steamboats@yahoogroups.com
        > Subject: [pop-pop-steamboats] Re: Peter R Payne and proper boats.
        >
        > Hi David,
        > I think the condensing is done in the tube, which creates another
        > problem. Condensing steam in a tiny tube is a lot quicker than
        doing
        > it in a big tube.
        > An interesting aspect of Paynes original patent is using the
        momentum
        > of the returning water to compress the remaining steam in the
        boiler.
        > This should raise the boiling point so the steam has more kick to
        it.
        > If this effect is significant I have no idea.
        > More important I suspect is to have a forward facing intake and
        > valves.
        > Also, what about an output nozzle? you can significantly increase
        the
        > velocity of water coming out of a hosepipe by sticking your finger
        > over the end.
        > This would also increase the pressure in the boiler and give the
        > whole thing more go?
        >
        > Dick
        >
        >
        >
        > --- In pop-pop-steamboats@yahoogroups.com, "David Halfpenny"
        > <dh1@> wrote:
        > >
        > >
        > >
        > > --------------------------------------------------
        > > From: "Richard Mundy" <coracles18@>
        > > Sent: Tuesday, January 20, 2009 7:44 PM
        > >
        > > > As the engines grow bigger there is a need to create a lot of
        > steam a
        > > > lot faster.
        > >
        > > AND then condense a tube-full of it in a similar time, in the
        very
        > boiler
        > > you have just heated it in!
        > >
        > > That is exactly the snag that Newcomen had - though with much
        less
        > thermal
        > > capacity to heat and cool each pulse.
        > >
        > > David 1/2d
        > >
        >
        >
        >
        > ------------------------------------
        >
        > Yahoo! Groups Links
        >
      • Richard Mundy
        Hi Jean-Yves, you keep knocking down my skittles:-). Seriously, I value your input hugely. Apart from a few experiments perhaps 10 years ago, I am coming at
        Message 3 of 29 , Jan 21, 2009
          Hi Jean-Yves,
          you keep knocking down my skittles:-).
          Seriously, I value your input hugely. Apart from a few experiments
          perhaps 10 years ago, I am coming at this subject from a 'what if'
          angle. I remember my biscuit tin/blow lamp boat moved forwards then a
          little back per cycle. So there is a slight reverse pull on the
          intake. I suspect tho that that the valves unless very carefully
          designed would further reduce efficiency and as you suggest make the
          forward facing inlet pointless.

          On the subject of nozzles, I have no experience, I just wondered if
          it had been tried.

          Conventional boilers work at high pressure so the steam can hold more
          energy. In a pop pop the boiler is, via the water, open to the
          atmosphere. effectively like a kettle, and the steam produced is very
          rapidly condensed by contact with the water and the unlagged exit
          tube. All this accounts for at least some of the inefficiency of the
          pop pop, hence throttling the output to up the pressure and speed up
          the output flow. But will it still work? If it actually reduces
          efficiency, why?

          Dick


          --- In pop-pop-steamboats@yahoogroups.com, "Jean-Yves Renaud"
          <boite.de.j-y@...> wrote:
          >
          > Hi Dick,
          > I would like to comment 2 topics of your last post: facing intake
          and
          > nozzle.
          > 1°) Facing intake.
          > Everybody thinks at the beginning that using a facing intake (and
          > valves) could improve the performance of pop-pop propulsion. Even
          > Peter Payne thought that. But facing intake is useless, or more
          > exactly so inefficient that it becomes useless.
          > • By math demo it can be proven that the effect of such a
          > modification is negligible.
          > • For those who dislike math, there is an easy way to check
          > that sucking is far less efficient than blowing. Try to blow a
          candle
          > by sucking air!
          > • In addition, to prove this inefficiency, 2 years ago I built
          > a small boat with an electric pump to show that sucking water on
          the
          > bow has a negligible impact; though a jet backward propels. The
          > pulling force (when sucking) was roughly 20 millions times weaker
          > than the pushing one.
          > 2°) Nozzle.
          > The thrust of a waterjet evolving with the square of the velocity
          of
          > the water that is expelled it seems evident that a nozzle could
          > improve the performance. However, on a pop-pop engine a nozzle acts
          > also on the frequency, stroke volume…and this is detrimental. We
          > don't know enough to give precise figures, but it seems that the
          best
          > nozzle has a diameter reduced by only 5 to 10%. On this forum Daryl
          > is very likely the one who has got the best practical knowledge on
          > this topic. Most of his engines are provided with nozzles and his
          > engines are among the best ones if not the best.
          > Jean-Yves
          >
          >
          > --- In pop-pop-steamboats@yahoogroups.com, "Richard Mundy"
          > <coracles18@> wrote:
          > >
          > > Hi David,
          > > I think the condensing is done in the tube, which creates another
          > > problem. Condensing steam in a tiny tube is a lot quicker than
          > doing
          > > it in a big tube.
          > > An interesting aspect of Paynes original patent is using the
          > momentum
          > > of the returning water to compress the remaining steam in the
          > boiler.
          > > This should raise the boiling point so the steam has more kick to
          > it.
          > > If this effect is significant I have no idea.
          > > More important I suspect is to have a forward facing intake and
          > > valves.
          > > Also, what about an output nozzle? you can significantly increase
          > the
          > > velocity of water coming out of a hosepipe by sticking your
          finger
          > > over the end.
          > > This would also increase the pressure in the boiler and give the
          > > whole thing more go?
          > >
          > > Dick
          > >
          > >
          > >
          > > --- In pop-pop-steamboats@yahoogroups.com, "David Halfpenny"
          > > <dh1@> wrote:
          > > >
          > > >
          > > >
          > > > --------------------------------------------------
          > > > From: "Richard Mundy" <coracles18@>
          > > > Sent: Tuesday, January 20, 2009 7:44 PM
          > > >
          > > > > As the engines grow bigger there is a need to create a lot of
          > > steam a
          > > > > lot faster.
          > > >
          > > > AND then condense a tube-full of it in a similar time, in the
          > very
          > > boiler
          > > > you have just heated it in!
          > > >
          > > > That is exactly the snag that Newcomen had - though with much
          > less
          > > thermal
          > > > capacity to heat and cool each pulse.
          > > >
          > > > David 1/2d
          > > >
          > >
          >
        • Richard Mundy
          Hi David, thanks for putting this into perspective, this is entirely for fun and is a subject that can be tinkered with indefinately, but as Jean- Yves points
          Message 4 of 29 , Jan 21, 2009
            Hi David,
            thanks for putting this into perspective, this is entirely for fun
            and is a subject that can be tinkered with indefinately, but as Jean-
            Yves points out, the likelyhood of a high powered big pop pop is very
            slim.
            Time to start torturing metal!!

            Dick

            --- In pop-pop-steamboats@yahoogroups.com, "David Halfpenny"
            <dh1@...> wrote:
            >
            > --------------------------------------------------
            > From: "Richard Mundy" <coracles18@...>
            > Sent: Tuesday, January 20, 2009 10:02 PM
            > To: <pop-pop-steamboats@yahoogroups.com>
            > Subject: [pop-pop-steamboats] Re: Peter R Payne and proper boats.
            >
            > > Hi David,
            > > I think the condensing is done in the tube, which creates another
            > > problem. Condensing steam in a tiny tube is a lot quicker than
            doing
            > > it in a big tube.
            > > An interesting aspect of Paynes original patent is using the
            momentum
            > > of the returning water to compress the remaining steam in the
            boiler.
            > > This should raise the boiling point so the steam has more kick to
            it.
            > > If this effect is significant I have no idea.
            > > More important I suspect is to have a forward facing intake and
            > > valves.
            > > Also, what about an output nozzle? you can significantly increase
            the
            > > velocity of water coming out of a hosepipe by sticking your finger
            > > over the end.
            > > This would also increase the pressure in the boiler and give the
            > > whole thing more go?
            > >
            >
            > This is basically a bit of fun in the bathtub. But if Payne missed
            > something big, as well he might, then we aren't going to find it in
            this
            > kind of conversation, entertaining as it is.
            >
            > We are talking about a resonant system involving an air spring of
            unknown
            > size, ever-reversing heat flow, the properties of steam and water
            under
            > rapidly varying pressure, and the movement of a heavy craft at low
            speed
            > under tiny fluctuating loads. There is virtually no experimental
            data, and
            > few if any of our members have either the maths, the mechanics or
            the
            > thermodynamics to discuss any part of it at a theoretical level.
            Despite
            > the simplicity of the device, it is vastly more complicated than,
            say, an
            > ordinary three cylinder compound marine steam engine. It has been
            usefully
            > demonstrated by Payne that when scaled up in a simple manner the
            power
            > required became enormous yet the result remained pathetic.
            >
            > What would be needed to improve on that would be a set of
            experiments in
            > which every part of the apparatus had rapid-acting pressure and
            temperature
            > sensors, backed up an ever more sophisticated non-linear
            computer "model"
            > based on real thermodynamics until the whole process was understood.
            >
            > The exciting thing is that this is actually all within the scope of
            a smart
            > pensioner with modest means.
            >
            > Meanwhile, the complexity is such that the best answer to questions
            about
            > valves and nozzles is still "Try it!" (Please.)
            >
            > David 1/2d
            >
          • David Halfpenny
            ... From: Richard Mundy Sent: Wednesday, January 21, 2009 7:31 PM ... That s the spirit! D
            Message 5 of 29 , Jan 21, 2009
              --------------------------------------------------
              From: "Richard Mundy" <coracles18@...>
              Sent: Wednesday, January 21, 2009 7:31 PM

              > Time to start torturing metal!!
              >
              That's the spirit! D
            • Jean-Yves Renaud
              Dick, your biscuit tin/blow lamp boat moved back and forth (more or less as every pop-pop boat) not because of the suction, but because of the inertia of the
              Message 6 of 29 , Jan 22, 2009
                Dick, your biscuit tin/blow lamp boat moved back and forth (more or
                less as every pop-pop boat) not because of the suction, but because
                of the inertia of the water contained inside the pipes.
                It very easy to demonstrate that the suction is not the cause. On a
                classic pop-pop boat with two pipes, just bend one on port and the
                other one on starboard. Thus, there will be no more thrust (port and
                starboard being equal and opposite). The boat will no longer progress
                forward, but it will go on vibrating back and forth as before.
                If you have a single pipe engine, just bend the outlet vertically
                downward and the result will be the same.
                Jean-Yves



                --- In pop-pop-steamboats@yahoogroups.com, "Richard Mundy"
                <coracles18@...> wrote:
                >
                > Hi Jean-Yves,
                > you keep knocking down my skittles:-).
                > Seriously, I value your input hugely. Apart from a few experiments
                > perhaps 10 years ago, I am coming at this subject from a 'what if'
                > angle. I remember my biscuit tin/blow lamp boat moved forwards then
                a
                > little back per cycle. So there is a slight reverse pull on the
                > intake. I suspect tho that that the valves unless very carefully
                > designed would further reduce efficiency and as you suggest make
                the
                > forward facing inlet pointless.
                >
                > On the subject of nozzles, I have no experience, I just wondered if
                > it had been tried.
                >
                > Conventional boilers work at high pressure so the steam can hold
                more
                > energy. In a pop pop the boiler is, via the water, open to the
                > atmosphere. effectively like a kettle, and the steam produced is
                very
                > rapidly condensed by contact with the water and the unlagged exit
                > tube. All this accounts for at least some of the inefficiency of
                the
                > pop pop, hence throttling the output to up the pressure and speed
                up
                > the output flow. But will it still work? If it actually reduces
                > efficiency, why?
                >
                > Dick
                >
                >
                > --- In pop-pop-steamboats@yahoogroups.com, "Jean-Yves Renaud"
                > <boite.de.j-y@> wrote:
                > >
                > > Hi Dick,
                > > I would like to comment 2 topics of your last post: facing intake
                > and
                > > nozzle.
                > > 1°) Facing intake.
                > > Everybody thinks at the beginning that using a facing intake (and
                > > valves) could improve the performance of pop-pop propulsion. Even
                > > Peter Payne thought that. But facing intake is useless, or more
                > > exactly so inefficient that it becomes useless.
                > > • By math demo it can be proven that the effect of such a
                > > modification is negligible.
                > > • For those who dislike math, there is an easy way to check
                > > that sucking is far less efficient than blowing. Try to blow a
                > candle
                > > by sucking air!
                > > • In addition, to prove this inefficiency, 2 years ago I built
                > > a small boat with an electric pump to show that sucking water on
                > the
                > > bow has a negligible impact; though a jet backward propels. The
                > > pulling force (when sucking) was roughly 20 millions times weaker
                > > than the pushing one.
                > > 2°) Nozzle.
                > > The thrust of a waterjet evolving with the square of the velocity
                > of
                > > the water that is expelled it seems evident that a nozzle could
                > > improve the performance. However, on a pop-pop engine a nozzle
                acts
                > > also on the frequency, stroke volume…and this is detrimental. We
                > > don't know enough to give precise figures, but it seems that the
                > best
                > > nozzle has a diameter reduced by only 5 to 10%. On this forum
                Daryl
                > > is very likely the one who has got the best practical knowledge
                on
                > > this topic. Most of his engines are provided with nozzles and his
                > > engines are among the best ones if not the best.
                > > Jean-Yves
                > >
                > >
                > > --- In pop-pop-steamboats@yahoogroups.com, "Richard Mundy"
                > > <coracles18@> wrote:
                > > >
                > > > Hi David,
                > > > I think the condensing is done in the tube, which creates
                another
                > > > problem. Condensing steam in a tiny tube is a lot quicker than
                > > doing
                > > > it in a big tube.
                > > > An interesting aspect of Paynes original patent is using the
                > > momentum
                > > > of the returning water to compress the remaining steam in the
                > > boiler.
                > > > This should raise the boiling point so the steam has more kick
                to
                > > it.
                > > > If this effect is significant I have no idea.
                > > > More important I suspect is to have a forward facing intake and
                > > > valves.
                > > > Also, what about an output nozzle? you can significantly
                increase
                > > the
                > > > velocity of water coming out of a hosepipe by sticking your
                > finger
                > > > over the end.
                > > > This would also increase the pressure in the boiler and give
                the
                > > > whole thing more go?
                > > >
                > > > Dick
                > > >
                > > >
                > > >
                > > > --- In pop-pop-steamboats@yahoogroups.com, "David Halfpenny"
                > > > <dh1@> wrote:
                > > > >
                > > > >
                > > > >
                > > > > --------------------------------------------------
                > > > > From: "Richard Mundy" <coracles18@>
                > > > > Sent: Tuesday, January 20, 2009 7:44 PM
                > > > >
                > > > > > As the engines grow bigger there is a need to create a lot
                of
                > > > steam a
                > > > > > lot faster.
                > > > >
                > > > > AND then condense a tube-full of it in a similar time, in the
                > > very
                > > > boiler
                > > > > you have just heated it in!
                > > > >
                > > > > That is exactly the snag that Newcomen had - though with much
                > > less
                > > > thermal
                > > > > capacity to heat and cool each pulse.
                > > > >
                > > > > David 1/2d
                > > > >
                > > >
                > >
                >
              • Richard Mundy
                Hi Jean-Yves, Yet another thing to think about. I had thought about momentum of the water column, but not its inertia. Dick ... and ... progress ...
                Message 7 of 29 , Jan 23, 2009
                  Hi Jean-Yves,

                  Yet another thing to think about. I had thought about momentum of the
                  water column, but not its inertia.

                  Dick



                  --- In pop-pop-steamboats@yahoogroups.com, "Jean-Yves Renaud"
                  <boite.de.j-y@...> wrote:
                  >
                  > Dick, your biscuit tin/blow lamp boat moved back and forth (more or
                  > less as every pop-pop boat) not because of the suction, but because
                  > of the inertia of the water contained inside the pipes.
                  > It very easy to demonstrate that the suction is not the cause. On a
                  > classic pop-pop boat with two pipes, just bend one on port and the
                  > other one on starboard. Thus, there will be no more thrust (port
                  and
                  > starboard being equal and opposite). The boat will no longer
                  progress
                  > forward, but it will go on vibrating back and forth as before.
                  > If you have a single pipe engine, just bend the outlet vertically
                  > downward and the result will be the same.
                  > Jean-Yves
                  >
                  >
                  >
                  > --- In pop-pop-steamboats@yahoogroups.com, "Richard Mundy"
                  > <coracles18@> wrote:
                  > >
                  > > Hi Jean-Yves,
                  > > you keep knocking down my skittles:-).
                  > > Seriously, I value your input hugely. Apart from a few
                  experiments
                  > > perhaps 10 years ago, I am coming at this subject from a 'what
                  if'
                  > > angle. I remember my biscuit tin/blow lamp boat moved forwards
                  then
                  > a
                  > > little back per cycle. So there is a slight reverse pull on the
                  > > intake. I suspect tho that that the valves unless very carefully
                  > > designed would further reduce efficiency and as you suggest make
                  > the
                  > > forward facing inlet pointless.
                  > >
                  > > On the subject of nozzles, I have no experience, I just wondered
                  if
                  > > it had been tried.
                  > >
                  > > Conventional boilers work at high pressure so the steam can hold
                  > more
                  > > energy. In a pop pop the boiler is, via the water, open to the
                  > > atmosphere. effectively like a kettle, and the steam produced is
                  > very
                  > > rapidly condensed by contact with the water and the unlagged exit
                  > > tube. All this accounts for at least some of the inefficiency of
                  > the
                  > > pop pop, hence throttling the output to up the pressure and speed
                  > up
                  > > the output flow. But will it still work? If it actually reduces
                  > > efficiency, why?
                  > >
                  > > Dick
                  > >
                  > >
                  > > --- In pop-pop-steamboats@yahoogroups.com, "Jean-Yves Renaud"
                  > > <boite.de.j-y@> wrote:
                  > > >
                  > > > Hi Dick,
                  > > > I would like to comment 2 topics of your last post: facing
                  intake
                  > > and
                  > > > nozzle.
                  > > > 1°) Facing intake.
                  > > > Everybody thinks at the beginning that using a facing intake
                  (and
                  > > > valves) could improve the performance of pop-pop propulsion.
                  Even
                  > > > Peter Payne thought that. But facing intake is useless, or more
                  > > > exactly so inefficient that it becomes useless.
                  > > > • By math demo it can be proven that the effect of such a
                  > > > modification is negligible.
                  > > > • For those who dislike math, there is an easy way to check
                  > > > that sucking is far less efficient than blowing. Try to blow a
                  > > candle
                  > > > by sucking air!
                  > > > • In addition, to prove this inefficiency, 2 years ago I built
                  > > > a small boat with an electric pump to show that sucking water
                  on
                  > > the
                  > > > bow has a negligible impact; though a jet backward propels. The
                  > > > pulling force (when sucking) was roughly 20 millions times
                  weaker
                  > > > than the pushing one.
                  > > > 2°) Nozzle.
                  > > > The thrust of a waterjet evolving with the square of the
                  velocity
                  > > of
                  > > > the water that is expelled it seems evident that a nozzle could
                  > > > improve the performance. However, on a pop-pop engine a nozzle
                  > acts
                  > > > also on the frequency, stroke volume…and this is detrimental.
                  We
                  > > > don't know enough to give precise figures, but it seems that
                  the
                  > > best
                  > > > nozzle has a diameter reduced by only 5 to 10%. On this forum
                  > Daryl
                  > > > is very likely the one who has got the best practical knowledge
                  > on
                  > > > this topic. Most of his engines are provided with nozzles and
                  his
                  > > > engines are among the best ones if not the best.
                  > > > Jean-Yves
                  > > >
                  > > >
                  > > > --- In pop-pop-steamboats@yahoogroups.com, "Richard Mundy"
                  > > > <coracles18@> wrote:
                  > > > >
                  > > > > Hi David,
                  > > > > I think the condensing is done in the tube, which creates
                  > another
                  > > > > problem. Condensing steam in a tiny tube is a lot quicker
                  than
                  > > > doing
                  > > > > it in a big tube.
                  > > > > An interesting aspect of Paynes original patent is using the
                  > > > momentum
                  > > > > of the returning water to compress the remaining steam in the
                  > > > boiler.
                  > > > > This should raise the boiling point so the steam has more
                  kick
                  > to
                  > > > it.
                  > > > > If this effect is significant I have no idea.
                  > > > > More important I suspect is to have a forward facing intake
                  and
                  > > > > valves.
                  > > > > Also, what about an output nozzle? you can significantly
                  > increase
                  > > > the
                  > > > > velocity of water coming out of a hosepipe by sticking your
                  > > finger
                  > > > > over the end.
                  > > > > This would also increase the pressure in the boiler and give
                  > the
                  > > > > whole thing more go?
                  > > > >
                  > > > > Dick
                  > > > >
                  > > > >
                  > > > >
                  > > > > --- In pop-pop-steamboats@yahoogroups.com, "David Halfpenny"
                  > > > > <dh1@> wrote:
                  > > > > >
                  > > > > >
                  > > > > >
                  > > > > > --------------------------------------------------
                  > > > > > From: "Richard Mundy" <coracles18@>
                  > > > > > Sent: Tuesday, January 20, 2009 7:44 PM
                  > > > > >
                  > > > > > > As the engines grow bigger there is a need to create a
                  lot
                  > of
                  > > > > steam a
                  > > > > > > lot faster.
                  > > > > >
                  > > > > > AND then condense a tube-full of it in a similar time, in
                  the
                  > > > very
                  > > > > boiler
                  > > > > > you have just heated it in!
                  > > > > >
                  > > > > > That is exactly the snag that Newcomen had - though with
                  much
                  > > > less
                  > > > > thermal
                  > > > > > capacity to heat and cool each pulse.
                  > > > > >
                  > > > > > David 1/2d
                  > > > > >
                  > > > >
                  > > >
                  > >
                  >
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