Loading ...
Sorry, an error occurred while loading the content.

Re: [pop-pop-steamboats] Our new members

Expand Messages
  • Donald Qualls
    ... I ll have to go look at mine; I couldn t get some pieces apart (they seem to be assembled with one-time latch-in parts, you d break them before they d
    Message 1 of 17 , Dec 1, 2007
    • 0 Attachment
      brian458666@... wrote:

      > It seems that each
      > manufacturer incorporates their own flaws so my standard backup is a french
      > press. But all of mine have check valves molded into the bottom of the
      > reservoir.

      I'll have to go look at mine; I couldn't get some pieces apart (they
      seem to be assembled with one-time latch-in parts, you'd break them
      before they'd fully disassemble), so it's very possible it has a check
      valve I missed. That would make a lot more sense in terms of avoiding
      bubbling back up through the tank, and it would only need a small
      plastic ball trapped in the joint between two pieces.

      --
      If, through hard work and perseverance, you finally get what you want,
      it's probably a sign you weren't dreaming big enough.

      Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com

      Opinions expressed are my own -- take them for what they're worth
      and don't expect them to be perfect.
    • Double Diamonds
      i was also looking into the possibility of using pulse-jet designs to improve on putt-putt engine work and was considering that it might allow for a faster
      Message 2 of 17 , Jul 26, 2013
      • 0 Attachment
        i was also looking into the possibility of using pulse-jet designs to improve on putt-putt engine work and was considering that it might allow for a faster engine cycle and quiet running from the lack of a diafram might allow more speed

        --- In pop-pop-steamboats@yahoogroups.com, Donald Qualls <silent1@...> wrote:
        >
        > David Halfpenny wrote:
        > > ----- Original Message -----
        > > From: "Donald Qualls" <silent1@...>
        > >
        > >>> There: the fundamentals of Mechanical Engineering on a postcard!
        > >> Well, at least as it stood ca. 1900, when internal combustion wasn't yet
        > >> a major player in the prime mover game.
        > >
        > > OK then: An Infernal Confusion engine:
        > > - compresses a lump of air,
        > > - heats it up a lot
        > > - expands it (providing a power stroke)
        > > - lets it escape along with the products of combusion (which may also
        > > provide a reaction thrust)
        >
        > Of course, this cycle, like the Rankine, can be used either in "batch"
        > mode or in "continuous" mode. Common piston, rotary, and pulse-jet
        > engines operate in pulsed or "batch" mode, where a discrete "lump" of
        > working fluid goes through the entire cycle independent of other
        > charges, while ramjets, turbojets and turbofans and at least one variant
        > piston engine (an internal combustion version of an elbow engine)
        > operate in continuous mode, where all parts of the cycle operate on a
        > flowing stream of working fluid (rather like the difference between pot
        > distillation and a distillation column, or lab synthesis vs. an
        > industrial process).
        >
        > > The one closest to the pop-pop is the pulse-jet or doodelbug engine, which
        > > also uses an oscillating column of fluid in a backwards-pointing tube. (My
        > > parents weren't very fond of these as they were married in London in August
        > > 1944.) In this case, the resonant pressure wave opens and closes the air
        > > inlet valve, sucks in and atomises the liquid fuel and compresses the
        > > ingested air. Ignition is usually by contact between the explosive mixture
        > > and the hot walls of the combustion chamber.
        > > The result is very simple and powerful model boat engine that is several
        > > decibels noisier than a pop-pop
        >
        > The classic valved pulsejet actually has a front intake and almost
        > entirely one-way flow, and model airplane versions have a venturi
        > carburetor built into the intake at the forward end (the German design,
        > too large to work well with a flat reed valve, incorporated the fuel
        > delivery into the grid that held the valves, so didn't as much resemble
        > a simple venturi carburetor).
        >
        > There are actually a couple valveless pulse jets that are even closer to
        > a pop-pop in operation; all compression and flow control is due to
        > pressure pulses in resonance with the pipe, and both pipe openings face
        > backward and produce thrust (though the designs I've seen have them
        > different lengths and the overall flow is from the shorter pipe to the
        > longer; there has to be some directional flow to keep drawing in fresh
        > air and fuel and removing combustion products, of course, but it could
        > be worth testing to see if this would be the case with our kind of
        > pop-pop, since tuning the tubes to product directional flow has the
        > potential to greatly increase the efficiency of the engine). The
        > resonance frequency in these, in hobbyist scales, tends to be in the
        > mid-upper audible range, leading them to produce a very distinctive
        > screaming sound in addition to the usual loud roar of any jet exhaust.
        >
        > > David 1/2d
        > >
        > > There are one or two additional details, but the core science behind post
        > > mediaeval Mechanical Engineering isn't mechanics, or mechanisms, or
        > > materials, important as they all are: it's thermodynamics.
        >
        > Yep, pretty much anything invented since James Watt improved the pumping
        > engine at the mine where he worked (by inventing, out of laziness, an
        > automatic valve gear to replace the continuous attention of a boy)
        > depends on thermodynamics, at least until you start getting into
        > practical electricity in the late 19th century. At that point,
        > Maxwell's laws of electromagnetism become the important ones...
        >
        > --
        > If, through hard work and perseverance, you finally get what you want,
        > it's probably a sign you weren't dreaming big enough.
        >
        > Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com
        >
        > Opinions expressed are my own -- take them for what they're worth
        > and don't expect them to be perfect.
        >
      Your message has been successfully submitted and would be delivered to recipients shortly.